TW550295B - Method for producing molten iron having low phosphorus content - Google Patents

Abstract

It is an object of the present invention to carry out an effective dephosphorization treatment by adding small amount of refining agent without adding large amount of CaF2. The present invention found out that extremely effective dephosphorization using inhomogeneous molten state of slag is made possible by supplying oxygen gas and refining agent in the specified form into surface of molten bath under a condition that the amount of slag after the treatment is considerably reduced in comparison with the prior arts. The dephosphorization is carried out by blowing the oxygen gas and at least a part of the refining agent through top blowing lance onto the surface of the molten bath. The amount of slag after the treatment is 30 kg/ton of molten iron or less, preferably 20 kg/ton of molten iron or less, more preferably 10 kg/ton of molten iron or less. Moreover, the dephosphorization is preferably subjected to molten iron of 0.15 mass % or less Si, more preferably 0.07 mass % or less Si, most preferably 0.03 mass % or less Si.

Description

550295 V. Description of the invention (1) TECHNICAL FIELD The present invention relates to a method for efficiently producing low-phosphorus molten pig iron by performing a dephosphorization treatment as a molten pig iron pretreatment. Background Art A molten pig iron pretreatment method in which dephosphorization treatment is performed at a molten pig iron stage is widely used instead of the previous converter furnace method. The reason is that the lower the refining temperature of the dephosphorization reaction, the easier it is to perform thermodynamically, and the dephosphorization treatment can be performed with a smaller amount of the refining agent. Generally, the pretreatment of molten pig iron is to first add a solid oxygen source such as iron oxide to the molten pig iron, and perform desiliconization treatment. After removing the slag generated by the desiliconization treatment, a refining agent is added to perform dephosphorization treatment. Generally, the dephosphorizing chain-refining agent is a CaO-based refining agent using lime or the like, and the oxygen source is a solid oxygen source (such as iron oxide) and gaseous oxygen. The processing container is a torpedo car, a ladle, or a converter-type container g. To promote the slagging of CaO-based refining agents, CaF 剂 fluorite is widely added). The prior art dephosphorization treatment conditions are, for example, disclosed in Japanese Patent Application No. 7-7007626, with a test value of 0.6 or more and 2.5 or less, a processing end temperature of m0C or more and 1 400 C or less, and a stirring power of 10 kg / Conditions for dissolving pig iron above seven tons, sending ^ speed of 2.5NmV for dissolving pig iron above t ON. The reason why the slag basicity is 2.5 or less in this technology is that under the above-mentioned alkaline sound, the slag fluidity is deteriorated, so it must be treated at a level that is not conducive to dephosphorization. X, if it is 2.5 or more, the higher the dissolution test, the more smoothly

550295

Furthermore, in Japanese Patent Application Laid-Open No. 8-3Π 523, it is revealed that for the melting furnace type = molten pig iron, Ca 0 powder and 〇7 ~ 2〇Nm3 / min / dissolved pig iron ton are blown in through an upper blowing spray, and The method of blowing 0.05 ~ 0.30Nm3 / min / melting pig iron ton mixing gas from the furnace bottom or side wall of the conversion furnace type container. According to this method, the amount of oxygen supplied by blowing the upper bottom into the blowing chain is appropriately adjusted. ' Then, the slag can be generated quickly (ca 0 slag slagging) and the ρ e 〇 concentration in the dross slag can be appropriately adjusted, and an efficient disc removal process can be performed. Based on the above-mentioned JP 7-70 626 and JP 8-3 1 1 523, the other> linhua pig iron's delinning refining technology can be identified if it is discussed using a descaling balance method. The premise is that the slag is uniformly melted and the slag-metal is close to equilibrium. Therefore, the dephosphorization capacity of the slag (phosphorus distribution 1? = Mass' mass% (P): p concentration in the slag, mass% [P]: P concentration in the metal) and slag volume are also based on such premises Decide and proceed.仏 / Chazhi extremely matching Lp is dependent solution> check, the higher the slag test, the higher the dish distribution Lp. However, in the past, if the basicity of the slag is increased, the fluidity of the slag is deteriorated ', which is a disadvantageous condition for descaling. On the other hand, if the melt fracture test becomes low, the filling distribution L p becomes low, so it is necessary to add a lot of lime (and add Si 02 source if necessary) and increase the amount of slag. From the above, it is known that the prior art is set to the slag basicity necessary to ensure the specified phosphorus distribution Lp, and under this slag basicity, the amount of slag necessary to reach the target p is determined, and the refining agent is added, but In view of the relationship of slag fluidity, the slag test cannot be improved in this way. Therefore, in the usual dephosphorization treatment of molten pig iron with Si content of about 0.2% by mass,

91119784.ptd Page 9 550295 V. Description of the invention (3) Slag amount (approximately clear amount after treatment) of 40 ~ 50kg / dissolved pig iron ton, — operation. For example, in Japanese Patent Application Laid-Open No. 8-3 1 1 523, the amount of (finishing agent) is determined based on the amount of f ^ in the molten pig iron to be descaled, and the P content before treatment is normal. About 0.10% by mass, about 20 kg of CaO dissolved in pig iron is dissolved, and the capacity is refined in dephosphorization refining. The existing slag is compared to the above-mentioned CaO, which is produced by the above-mentioned input CaO. = Si〇2 part generated by the disintegration reaction of molten pig iron, dephosphorization 1 should be generated by ζ05 part, fusion part generated from other molten pig iron (Fe〇M-n〇, etc.), by The radon part brought in the previous step, the slag part (Al203, MgO, etc.) generated by the melting of the furnace body, the original slag attached to the furnace body, check: the dazzle brought by the broken iron input The crushed portion is added by the Hyun Kuang workers such as the added ore knife and others. Generally, this amount (refined after processing / charing) is 2 to 2.5 times the amount of CaO. In the case of CaO around pig iron ton, it is necessary to put in after treatment: 0 kg / ~ 50 kg / melt pig iron ton. —Sw; year, Γΐ 保 ΐ, etc .... requires to reduce the amount of slag that occurs during the defilling step i: ί ϊ ν, but as in the prior art above; the reduction of the dross has its limit, so the helmet Requirement of eight μ. 、、 / 2: charge and cut and reduce slag. ^: Regarding the CaF2 added to promote the refining of the refining agent, in recent years, considering the effect of fluorine on the mounting environment,

The corrosion of CaF is also required to reduce the limit 2 in the steel sum chain. Therefore, the use of CaI? 2 to increase the dephosphorization efficiency is also extremely effective.

Page 10 550295 V. Description of the invention (4) The purpose of the present invention is to provide an efficient dephosphorization treatment without adding a large amount of chain agent, and | 2 and a low level of low slag generation. The manufacturing method of phosphorus-dissolved pig iron can also be greatly reduced in the dephosphorization refining of molten pig iron. For the refining agent of dissolved, ca 0 sources, the supply method of oxygen source is to add iron source to iron and effectively promote the production of FeO. In terms of blowing, the method of lowering the temperature and blowing the oxygen from the surface is suitable. In this type of oxygen, the combined pig iron bath container can be divided into the exposed part of the slag by using the energy of oxygen to squeeze out the slag. Surface (the existence of molten slag in the molten pig iron refining vessel is not uniform, but Yu et al. Did not grasp that the melting vessel in the refining vessel is maintained; =, the inventor ^ thinks the direction, but for less refining The review is based on the dephosphorization refining method of = dephosphorization efficiency, the condition that the amount of female son-in-law of the company H is reduced by a considerable degree compared with the previous technology; the content of the molten iron in the molten slag after the treatment is referred to as' better to make the Under the condition that the refining agent is supplied to the melt in a specific form, the thinking direction of uniformly melting oxygen and slag is opposite, = surface, and it is found that it can be decomposed very efficiently compared with the previous order state. The characteristics of homogeneous melting are Yu Bao :: sheng 1: ί ί :: The method is based on such findings, and its agent is used to dissolve pig iron and add oxygen to the source of pretreatment and ―source refining iil iron irt refining oxygen and at least-part of the refining Blow to a; k Λ compound Descaling treatment, and the dissolution amount after the treatment is g "chemical pig iron ton or less. A more preferable slag amount after the treatment is 550,295. Fifth, the description of the invention (5) 20 kg / dissolved pig iron ton 'is particularly IOkg / The molten pig iron is below t0n. According to the method of the present invention, the mechanism of direct dephosphorization reaction by blowing oxygen to the molten pig iron bath surface area and fixing P in the solid phase main body on the outer area , It is possible to perform an efficient descaling treatment without adding a large amount of dagger and with a small amount of refining agent added. To make the effect of the present invention more practical, it is desirable to perform a dephosphorization treatment on low-silicon molten pig iron. That is, it is expected For molten pig iron whose Si content is 0.15 mass% or less, preferably 0.07 mass% or less, and particularly preferably 0.03 mass% or less, it is subjected to a de-disc treatment, which can provide the optimal conditions for the stable production of the upper command. In addition, the dephosphorization reaction of the mechanism is that the refining agent supplied by the upper blowing spray gun is in a state of adding power to the melt. It is expected that at least the refining agent supplied by the upper blowing spray will be divided into: Molten pig iron Noodle area, more preferably ί ί At least part of the refining agent is blown to oxygen: the fire point generated by the iron bath surface of the dagger ... Specially, the refining agent ΐ 「1" partly uses oxygen as a carrier It is blown to the molten pig iron bath surface. Lending oxygen can promote the defilling reaction in the molten pig iron bath surface area where a large amount of Fe0 is generated. Inflammation: Fu 2 21 is added at 2kg / melt Pig iron—The following conditions or conditions where CaF is not added τ. ^ 0〇, 'Effective dephosphorization treatment at 1,000 times. = The invention is expected to refine the P content to 0.1 (%) by mass or more to crude steel. The required P content and the expected load are expected to make the solution dissolve after being removed from the dish: = lattice value), especially 卞. In this way, the continuous conversion furnace is 0.01% by mass and the conversion furnace There is virtually no use of manufacturing in the blow chain

550295 V. Description of the invention (6) The slag material can only be subjected to substantial decarburization refining. The present invention is an embodiment under the basic conditions as described above. The following various preferred r η %% π-shaped grievances are to change the supply rate of the refining agent blowing to the molten pig iron bath surface to iL CaO B (kg / min / molten pig iron =

Li V?-&Quot; ^ ^ ^ ^ ton); " Γ々 之 " It is acknowledged that the dephosphorization treatment is performed by the following formula (2). By this, the output of Fe0 and Ca0 can achieve higher dephosphorization efficiency through rolling. Li 1 is a ten-point balance, 0. 3 ^ A / B ^ 7… (1) 1. 2 ^ A / B ^ 2.5… (2) J 2. The state is to use a pot or torpedo container. Each line of the production line is blasted with oxygen and at least one of the essence through a blow-up spray, and the surface of the pig iron bath is melted, and the blast-spray and / or blown into the tube surface is immersed in the powder. The gas is blown into the molten pig iron, and then it can be defilled. With this, in the dephosphorization treatment of the pot or torpedo type container, the molten pig iron can obtain a moderate stirring effect and achieve a higher dephosphorization efficiency. It is better that the powder blown into the molten pig iron is a part of the refining agent by blowing into the nozzle, and the oxygen content of the gas blown through the surface of the bath of the pig iron is 0 · 7 N m3 / mi η It is preferable to dissolve pig iron below ton. Furthermore, 80% by mass or more of the refining amount added in the dephosphorization treatment is blown to the surface of the molten pig iron bath through an up-blowing lance, which is effective for efficient treatment. In addition, substantially the entire amount of the refining agent is transmitted through

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Page 13 550295

The top blowing spray is blown to the molten pig iron bath surface nozzle, and the amount of blowing agent added to the molten pig iron is added to the refining agent. In order to satisfy the dephosphorization treatment, the supply rate of solubility and oxygen is satisfied. With this, at the decarburization chain, the minimum necessary refining agent can be added, and (C1 / D1) > (C2 / D2) can be added.

Cl > C2 ··, and refining by blasting and blasting through immersion blasting and / or blowing into the ft mouth, plus: 20 ~ 80% by mass of £ is better, the effect caused by iron bath surface, And blow into the mix to achieve a good balance. Feeding rate of refining agent for chemical pig iron bath surface The following formulas (3) and (4) are used for the treatment without adding unnecessary amount of refining agent at the later stage of the treatment, so there is little efficient dephosphorization treatment. • (3) • (4) But ci: average value of refining agent supply rate converted to Ca0 in the early stage of dephosphorization treatment (kg / min / dissolved pig iron ton) C2 Mean value of agent supply rate (kg / m in / melted pig iron ton) D1: Average value of oxygen supply rate in the early stage of descaling treatment (Nm3 / min / molten pig iron ton) D 2 ·· Oxygen in the later stage of dephosphorization Average value of supply rate (Nm3 / min / molten pig iron ton) This third embodiment is a method for continuously and / or stepwise changing the supply rate of the refining agent and the supply rate of oxygen converted to Ca0 during the dephosphorization process. According to a fourth embodiment, for molten pig iron having an Si content of less than or equal to 0.15% by mass, oxygen and at least a part of the refining agent are blown to the melting point through an upper blowing spray.

91119784.ptd Page 14 550295 V. The invention is clear (8) The pig iron surface is stripped and processed, and in this stripping process, the amount of lime obtained by the following formula (5) ^ ca0 —p ( kg / dissolved pig iron (ton) and the amount of lime Wca0_Si (kg / dissolved pig iron ton) determined in the following (6) Take added lime as a refining agent. This makes it possible to perform an efficient dephosphorization treatment with a minimum required amount of refining agent.

Wca〇 ~ P = (Dissolved pig iron [p] —Target [P]) X (1 0/6 2) X 56 X 3/7? Cao --- (5) Dissolved pig iron [p] ·· Before dephosphorization treatment P concentration (% by mass) in molten pig iron Target [P]: P concentration (% by mass) in molten pig iron after target dephosphorization treatment acao (lime efficiency) = 0.5 to 1

Wca〇 ~ Si = Dissolved pig iron [Si] x (1 0/28) X 56 X 2-. (6) Ren> Valley pig iron [S i]: Si concentration in molten pig iron before defilling treatment ( Mass ° / 〇) In this fourth embodiment, 80% by mass or more of the lime content Wcao-P (but Wca0-p determined by ecaoq) is passed through an upper-blowing lance to the melting 1 iron bath It is better for efficient processing. In addition, as the refining agent equivalent to Wca ^ ji in lime, one or more selected from the group consisting of lime powder, burnt lime, and limestone with unreacted Ca a 0 may be used. The fifth embodiment is to melt the cast iron bath surface by blowing oxygen or blowing a refining agent as defined in the following formula (7), or by using oxygen as a carrier gas. Can be reduced with a small amount of refining agent

91119784.ptd

550295 V. Description of the invention (9) Effective dephosphorization treatment. LL〇X exp {(^ 〇e 78χ Lh) / l〇} ... (7) L〇 = 63 x {(F02 / n) / dt} 2/3 ^ The height of the gun (mm) ) 02 η d + P • Oxygen supply speed from upper blow nozzle (Nm3 / hr) No. of nozzle holes of upper blow nozzle Nozzle hole diameter of upper blow nozzle (mm) (However, nozzle diameter of multiple nozzle holes When it is different, it is the average pore size of all nozzle holes.), 第, 、 & shape complaint is that for the dissolved pig iron with Si content of 0 · 15% by mass or less, the addition amount of CaI? 2 is 1kg / melt. Under the condition that the pig iron is not higher than or no CaF2 is added, the molten pig iron bath surface is blown with oxygen and at least a part of the refining agent through an upper blowing spray to perform dephosphorization treatment, and the molten pig iron temperature at the end of the dephosphorization treatment For ^ ⑼It ~ ;! 45 0 t. This makes it possible to perform an efficient dephosphorization treatment even in a high-temperature treatment, and to sufficiently secure a sufficient heat in the subsequent steps. A seventh embodiment is a method of supplying a substance that dissolves the heat of the molten pig iron with a chemical reaction and / or a thermal decomposition reaction in the bath area of the molten pig iron supplied with oxygen, and absorbs heat. Thereby, the slagging of the refining agent is not hindered, and the temperature rise in the molten pig iron bath surface area where oxygen is supplied can be suppressed, so that higher dephosphorization efficiency can be achieved. The gas is preferably on the fire point of the molten pig iron bath surface. This seventh embodiment is to supply at least a part of the substance that absorbs the heat of molten pig iron through a chemical reaction and / or a thermal decomposition reaction, and supply it to the blowing oxygen. anti-

91119784.ptd Page 16 550295 V. Description of the invention (ίο) Materials that should be and / or pyrolyzed to absorb the heat of molten pig iron from carbon dioxide, hydrothermal gas, nitrogen oxides, metal carbonates, metal compounds Among them, one or more kinds are selected. One or more kinds are selected from carbonates of metals that generate diH2O through thermal decomposition, and oxides of metals that generate co2 or h2O through thermal decomposition. Also, among them,

One or more selected from CaC03, Ca (OH) 2, and CaMg (C03) 2 is preferable. Also, this seventh embodiment is one or more selected from CM, Ca⑽) 2, and CaMg (c0) 2 in the molten pig iron bath surface area 2 where oxygen is supplied, and the chain-forming substance is produced through chemical reaction and / Or the thermal decomposition reaction will be = a substance that absorbs heat by heat 'instead of the refining agent of the source of Ca0-; ^ S ΐ 1 This embodiment is at least- Partially, it is preferable to supply to the fire point generated by blowing oxygen on the cold surface of molten pig iron. The second to seventh embodiments of the method of the present invention can be used separately. The conditions of the two or more embodiments can be combined arbitrarily. The more pieces of C, the more effective the method of the present invention is. . The detailed dephosphorization mechanism of molten pig iron with jgj plus 2 pounds of anxiety is to make SlO2 and Fe0 generated by oxygen supply in the refining container react and melt the melt. Homogeneous and highly dephosphorizing molten slag reacts with p in molten pig iron to dissolve pig iron. Based on this type of decoupling mechanism, as described above, it is determined to reach the goal 2 phosphorus ability, which determines the slag alkali. Degree, and under this slag alkalinity, do you reach the goal? The amount of necessary dross. In contrast, the inventors and others

9lH9784.ptd Page 17 550295

The implementation of the pig iron mechanism is to adopt Z to reduce the amount of slag after treatment to a considerable extent compared with the previous technology. '= It is better to make the Si content in the molten pig iron before the treatment as the specified process. Through the blow-up spray gun to the melting cold surface ^ treatment method, it was found that it can be treated with a very different dephosphorization refining based on completely different from the previous technology. Under yj, Gong Ming discovered the detailed and better gas sacrifice of the present invention according to this type of method. When adding + Γ \ 衣 & low-phosphorus molten pig iron to a container (refining container) that holds molten pig iron, Mix the gas through the blow-up spray gun. Rhenium is used as the refining agent to blow to the molten pig iron bath surface and is dephosphorized. Oxygen is blown through the surface of the pig iron bath, through the impingement bath surface, and Dali Fe0. Therefore, it is very important to promote the slagging of the refining agent: In the area where Fe0 is generated in large quantities, it is sprayed through the upper blow. "Ί 仏 4 refining agent can effectively promote the slagging of the refining agent (Ca0).妾 Can use 11 blow spray to blow oxygen and refining agent on molten pig iron bath surface, to-: Γ milk: external carrier gas (for example, inert gas such as '°' ~, 讦, etc.) also blow on cold iron bath surface Refining agent, and in this case, the area to be developed. a The molten pig iron bath surface oxygen is supplied to the two earths ^ 夂, · ,, 5 The molten pig iron bath surface area of 5 milk gas is the place where FeO is generated by the milk supply. milk

Ca0, can effectively promote the CaO degeneration and the ancient Γ nGaPn ice and aerated gas is called "fire point", the supply of refining agent is "it: rate. In addition, the contact effect of K 徂 仏 CaC ^ Fe0 on the window is too high. Γ

550295 V. Description of the invention (12) The fire point is the area of the ancient bath surface which is impacted by the gas jet of oxygen, because it is a region where molten pig iron is oxidized by oxygen. In addition, the Li Γ manifester obtains the ㈤ supply effect by using oxygen ;: said that the carrier gas of the refining agent is blown on the surface of the two sides ^ Li Ma Jia, in this case, is blown to the molten pig iron through γ ', Li Tong Bath surface, the basic mechanism that the agent === chain agent co-generates to generate an effective de-reaction is ^. When the refining agent (Ca0) is transported, FeO that occurs at the fire point of CaO reacts quickly and melts into a CaO-FeO-based melt. Jiao Ludou makes Γ η Γ a ^ sub-shaped, $ private & The 0-series melt is the movement month via oxygen ... the molten pig iron bath supplied by the oxygen with the fire point as the center: the area, while the area surrounding the low oxygen potential is first reacted with the Si in the melt, and Fe0 is reduced, and a stable solid phase such as 2Ca〇 · SiO2 is formed according to the Si content in the dissolved iron before the treatment. Furthermore, if the Sl content in the molten pig iron is reduced to some extent through the above reaction, the CaO-FeO-based melt will start to react with phosphorus to form a solid phase of 3Ca0 · p205. As a result, a considerable amount (or most) of the molten slag which was generated by the dephosphorization treatment and was sequentially extruded from the molten pig iron bath surface area supplied by the oxygen having a medium ignition point to the outer area was 2Ca. · Sio: 3Ca0, · P, 205 stable solid phase patterns exist. The 2 solid phase slag formed in this way is very stable, so it will not melt again even if the slag has a low basicity.

Page 19 550295 V. Description of the invention (13) If a direct dephosphorization reaction occurs in the area with the fire point as the center, then the slag extruded on the outer side is in the state of the solid phase, and it can be used in Effective dephosphorization with a small amount of refining agent added. In this way, the method of the present invention is based on the direct dephosphorization reaction in the molten pig iron bath surface area centered on the fire point, and the mechanism in which the solid phase-based slag fixes P in the outer area to efficiently remove P. Phosphorus treatment is its goal. However, a single pair of molten pig iron bath surface blowing oxygen and refining agent cannot achieve the dephosphorization reaction by the above mechanism. That is, in addition to the above-mentioned mechanism for stabilizing the delithonization reaction, the specific supply form of the above-mentioned oxygen and refining agent must be adopted, and the treatment should be performed with a very small amount of slag. Specifically, the amount of slag after treatment must be made specific. It is 30 kg / dissolved pig iron ton or less, preferably 20 kg / dissolved pig iron ton or less, more preferably 10 kg / dissolved pig iron ΐn or less. From the same point of view, it is desirable that the molten pig iron to be subjected to dephosphorization treatment is a low-temperature molten iron. Specifically, the si content is 0.15 mass% or less, and preferably 0.007 mass% or less. More preferably, the molten pig iron is not more than 0.3 mass%. Here, the reason why the present invention is treated with a small amount of slag is as follows. In order to effectively produce a de-disc reaction by the 述 Shi Shite 疋 mechanism, the oxygen passing through i ^% of the spray must be supplied to the molten pig iron by a so-called light blowing chain (low dynamic pressure) = t through the dephosphorization reaction through the above mechanism In the melted pig iron bath surface area where oxygen is supplied with the fire point as the center, it becomes the main FeO generation field: π ^ The slag Ca0 supplied in this area reacts with Fe0 to generate CaO-Fe (): y and this Ca〇— The Fe0-based melt is formed by directly reacting with P in molten pig iron to form 3CaO · P (Ί & general slag amount, and the body /. Here, in the state where the original slag layer was generated in the prior art, it is assumed Oxygen is light 91119784.ptd Page 20 550295 5. Description of the invention (14), Dong 、,, Ό 犄, because the injected oxygen can not penetrate the slag layer, the oxygen cannot be cut and supplied to the molten pig iron bath surface, so that Fe 〇 Insufficient j on the molten pig iron bath surface, therefore, the amount of Ca0-Fe0-based melts is also reduced. On the other hand, the right side uses a strong blowing chain (high dynamic pressure) to inject oxygen to penetrate the original molten metal. If it is supplied like a slag layer, the supply region becomes a strong stirring state, so it becomes Fe. It can be reduced by dissolving carbon in pig iron. In this case, you cannot ensure the necessary amount of 1 ^ 0, so the formation of Ca0-Fe0-based melts is also ^. If the amount of slag is increased in this way, Chain blowing, strong chain blowing i, and oxygen supply can not be stable to ensure the birth of the Fe0 and Ca0_Fe〇 system fusion, and it is difficult to generate a declassification response through the above mechanism. For this reason, in order to 7 The light blowing chain is appropriately supplied to the molten pig iron bath surface, and the dephosphorization reaction is effectively generated through the mechanism described above. It is an indispensable condition to specify the amount of slag and make the thickness t of the slag layer small. Therefore, in the present invention, After the treatment, it is checked that it is 30kg / melted pig iron ton or less as a condition. In addition, because of the above: 期望 from 'desired to reduce the amount of slag after treatment as much as possible, it is particularly desirable that f 0kg / melted pig iron t0n, less than It is preferably 10 kg / dissolved pig iron and less than 0.1 ton in the present invention. It is better to dephosphorize the low-silicon molten pig iron in the present invention: :: F. As described above, in the above-mentioned specific descaling mechanism , The area of molten pig iron bath surface where oxygen is supplied by the center of the fire The supplied slag Ca0 reacts with Fe0 and generates Ca〇_Fe〇 series two = +, and this Ca0_Fe〇 series melt is directly reacted with p in the molten pig iron, and the order is removed, but if the Si content in the molten pig iron is dissolved Is high, the generated Ca " e0-based melt is consumed in reaction to Shi Xi, and becomes insufficient

91119784.ptd $ 21 page 550295 5. Description of the invention (15): Direct dephosphorization reaction with the above. Because of &, the optimal conditions for the stable dephosphorization reaction via the above-mentioned machine are to satisfy the above-mentioned conditions for the amount of slag after treatment, and to sufficiently reduce the silicon content in the molten pig iron that has been dephosphorized. In addition, if the Si content in the pig iron is reduced, the amount of formation is also reduced, and the amount of slag after the treatment is reduced. Therefore, in the present invention, it is desired that ^ 1 3 f is G. 15 mass% or less, and a preferred amount% is 5%. 0.03% by mass or less of molten pig iron is subjected to decontamination treatment. The so-called post-treatment slag dissolution amount refers to the amount of molten metal present in the refined capacity Λ pig iron holding container at the end of the desilting process. Yes, here i) Vf ^ ^ ^ ^ CaO ^ (^ 'Dry balance method, add yttrium oxide' to the slag ^ chase 4 agents, and analyze the tracer concentration in the processed slag H can be determined by measuring the thickness of the slag, etc. Reason: Zhixuan root: According to the results of the test conducted by the authors, etc., it shows that the dephosphorization pig iron is contained in the human iron-pig iron. The relationship between the content, after the treatment of rk / ^. 3 is the width of the average value and deviation. Figure 1 is for 〇n ~ mg / dissolved pig iron tOn, more than 101 ^ melt production: η raw ㈣ / / Dissolved pig iron ton, more than 20 kg / melted pig iron ton ~ 301 ^ / ° n Over molten pig iron ton ~ 40 kg / melt pig iron, & 彳 彳 '40 kg /, Chemical pig iron t0n ~ 50kg / melted pig iron ton The content of p in each of the processed pig iron was' total collected 6 ~ 72ch of dissolution after defilling treatment. In this test, the ancient molten pig iron enters = household = Melt pig iron in desquamated bed and desilication treatment if necessary, followed by mechanical stirring and dissolution

91119784.ptd Page 22 550295 V. Description of the invention (16) After desulfurization treatment in a pig iron pot, dephosphorization treatment is performed in a converter furnace container (300 t 〇n). The molten pig iron components before the dephosphorization treatment are c: 4 · 5 ~ 4 · 7, Si · 0 · 01 ~ 〇 · 28% by mass, Mn: 0 · ΐ5 ~ 0.25% by mass, and P: 0.1〇 ~ 〇.11 Mass%, 3: 0.001 to 0.003 mass%. Use a particle size of 1 or less = ash powder as the refining agent for dephosphorization, and blow it to the molten pig iron bath surface by spraying with oxygen as the carrier gas. Not added to the refining agent. The blowing time was fixed at 10 minutes, and nitrogen gas was supplied from the furnace bottom at a temperature of 0.05 to 0.15 Nm3 / min / melted pig iron t0n in order to stir the molten pig iron. The original unit of lime and oxygen changes according to the Si content in the molten pig iron, but the value of lime and oxygen minus the desilication part (formation of the dicalcium silicate: 2Ca ^^ 2 stoichiometry part) Rhenium is 3.5 kg / melt pig iron t 〇η, 9 N m3 / melt pig iron ton. + The molten pig iron temperature before and after the dephosphorization treatment is 125 ° ~ 135 °. The amount of slag after treatment is calculated from the mass balance of the amount of lime added and the concentration of CaO in the slag (analyzed value of the slag). If, according to Fig. 1, the more the amount of slag after treatment, the more the p content after dephosphorization treatment will be, and the deviation on the upper limit side will also be larger. In contrast, after the treatment, the amount of slag is 3 | 0kg / melted pig iron ton or less, the deviation on the upper side of the p content is greatly reduced, and the maximum P content is also 0.020% by mass. Furthermore, the content of P in the melt after dephosphorization is 20 kg / melt pig iron after the treatment, and the amount of P is 0.015 mass%, and the amount of the slag after the treatment is 10 kg. / Dissolved pig iron ton or less, p content is at most 10000 mass%. For the above reasons, in the present invention, the amount of slag after the treatment is set to 30 kg / dissolved pig iron ton, preferably 20 kg / dissolved pig iron ton, particularly preferably 10 l ^ / melted pig iron. 〇

550295 V. Description of the invention ⑽—, in the hafnium pig iron Figure 2 is a graph showing the relationship between the Si content before the dephosphorization treatment and the slag amount after the treatment when the figure 丨 test is performed. According to the same figure, if the amount of ash is increased and the content of S in molten pig iron is high, the added content will increase the amount of slag. Therefore, the amount of slag has a high correlation with the melting and melting before treatment. Here, in order to make the weight of the molten slag after the treatment to be the content ratio and Γ, it is necessary to make the weight before the dephosphorization treatment > 々 20 to 0.15% by mass or less. Similarly, in order to melt the pig iron below ton after the treatment, the melt content before the dephosphorization treatment must be 0.07 mass% or less. In addition, in order to make the treatment: t iron in the content pig iron must be removed, Rolling before phosphorus treatment: f ΐ Clear amount is 20iig / Lacquer amount is 0 ^ Bailey 70M, and, in order to reduce pig iron 10kg / melt pig iron ton, the dephosphorization treatment must be fried / desired Si The content is 0.03% by mass or less. From the foregoing reasons, the present invention dephosphorizes the molten pig iron with an S1 content of 0.05 mass% or less, preferably 0.07 mass% or less, and preferably 0.03 mass% or less. In case, as described in / lj, if the content of Si in the molten pig iron is low, the e0-based melt will be consumed in reaction with Si and the proportion will be reduced. The effect of the dephosphorization reaction. The results in Figure 1 also reflect the fact that before the effective dephosphorization treatment, the amount of dissolved pig iron was used, and the content of Sl in iron can be adjusted as follows. It reduces the supply of melted pig iron and other molten pig iron manufacturing equipment, and reduces the pretreatment of raw materials. The content method is effective to suppress the total loading of the low silicic acid portion of silicon in the furnace used for the production of pig iron, as well as in the blast furnace. ^ The low temperature operation of the original reaction and the biased loading of charcoal etc. are 0.15 mass% or less. In the case of the si content of molten pig iron produced in a blast furnace, etc., such molten pig iron is not applied as such.

91119784.ptd Page 24 550295, Description of Invention (18) 5. The following desiliconization treatments and descaling treatments are also acceptable. On the other hand, when the Si content of the molten pig iron produced in a blast furnace or the like is 0.15% by mass, desiliconization treatment is performed before the dephosphorization treatment with a blast furnace casting bed and a molten iron furnace. And dephosphorization treatment was performed before the S i content of the lysate and dagger before the dephosphorization treatment was 0.15% by mass or less. Generally, the desilication treatment of molten pig iron can be performed by adding a solid carving source and oxygen to the molten pig iron. For example, the sintering powder and the grinding pot scale = oxygen solid oxygen source are placed on the bath surface of molten pig iron, and Blow in the bath or blow oxygen to the molten pig iron bath surface and insufflation method. ^ In addition to the addition of desulfurization, the desilication treatment of molten pig iron is in addition to the blast furnace casting bed and melting stage. For example, for the blast furnace casting bed to the molten pig iron, the molten pig iron is blown with stirring gas, and: :to

The CaO source adjusts the alkalinity of the slag, which can greatly reduce the iron of the fire temple and increase the reduction efficiency. In the case of oxidization, the slag such as desilication slag is discharged after the desilication treatment by dissolving pig iron, and in the case of fusing, the effective mixing of fusing is performed; ^ Inhibit the acid component by mechanical separation and manual operation. Therefore, L is dephosphorized after the slag is separated at the dephosphorization site. The method of melting pig iron from Luohua will be used in the method of the present invention, and there is no special limitation on the method of blowing on the # 〆 铁 铁面 面. Emulsions and refining agents are blown into the melted jet holes. _Li 'e.g.' blows oxygen from multiple stomata, $, from its 9U197E4.ptd 550295

V. Description of the invention (19) Other jet holes Inert gas supply can also be used as refining agent. There is gas around the pores, and the main refining agent, oxygen, then the blowing agent of the chain agent is the same as oxygen as the invention. In addition, iron oxide can be placed on top to dissolve or dissolve, such as oxygen, or other gases (such as i and nitrogen) that are also refining agents in the bath. Etc.) As a refining agent for carrier gas, the eight #knife should not melt molten iron bath surface. This can be added to the area of the molten iron bath bath area where the oxygen is supplied. In this case, 'the main air jet in the center of the front end of the air jet hole has a plurality of secondary air jets to blow up, and the secondary air holes will be used to oxygen The pores supply oxygen or the above oxygen to the molten pig iron bath with ice # ,,,, and eight% & π $ _ π &# external lice as the carrier gas' respectively.

Called Dog Fujia. In addition, even the Yin W can be sent with oxygen or other gas other than the above oxygen, which can be sprayed with different upper blows. The sum of the f version of the Li group. Order, but any of the above makes the refining agent the most efficient carrier gas for the μ refining agent. It is particularly desirable for the chemical industry to use pure oxygen gas or any of the oxygen-containing gas in the refining container. In addition to solid oxygen (for example, sintered powder, ground steel), etc .: : 2 It can be added by any method such as cracking and injection into the bath, and the above-mentioned molten pig iron bath surface can supply (blow) oxygen into the two. However, iron dephosphorization, the addition rate in the refining container is preferably 70%. The above (amount of oxygen conversion) is the oxygen passing through the upper surface, 0% iron bath surface. , B supply. Except for blowing part of the molten pig iron to the molten pig iron bath surface, it is injected into the molten pig iron bath and the bottom of the molten pig iron through the injection nozzle of the immersion spray gun and the molten pig iron holding container. , /, Supply CaO-based refining agents (usually CaO)

550295

550295 V. Description of the invention (21) Blown gas is blown into molten pig iron. In order to promote the fishery of Ca0, the previous de-disposal treatment has actually added flint). · In recent years, the use of fluorine in the environmental impact of plastics has also been required to inhibit the use of postage [this tp 'not added in the refining agent Contained impurities

That is to say, #a 二 f is only added with a small amount of caF2 to achieve high defilling efficiency. Therefore, even in the case where CaF2 is added in order to promote the Ca0 slag formation, Q is expected to add 2kg / melt as described below, the present invention can === two soil ": check the effect of significant reduction in loss, If it is not added to a very small amount, the fluidity of the molten slag can be further reduced, so that the above-mentioned effect can be further improved. 通 I Niutong: The P content of the molten pig iron in the T k treatment is 〇 ·} 〇 Mass% With-in the description, dephosphorization and refining to the p content required for crude steel, that is, the lower J is better. Worse, in a continuous conversion furnace blowing chain: 2 Guan Tai is not loaded with crushing material and Only substantial decarburization is carried out, ⑺ 可 = 付 ① Decarburization refining is extremely simple and the refining time can also reduce the amount of dross generated in two-iso decarburization refining, ③ because in decarburization: not used on fire The slag-making material can be used to add very high manganese yield to the manganese crescent shape when manganese ore is added as a manganese source. The following examples show several preferred embodiments of the method of the present invention. Through the application of the morphology, the present invention can further improve the reaction efficiency of the stone removal process. Refining agent for blowing to molten pig iron bath surface

550295 V. Description of the invention (22) Converted into CaO supply rate B (kg / min / melted pig iron t0n), and supply rate of radon gas blown to the molten pig iron bath surface A (N m3 / min / molten pig iron t On) The dephosphorization treatment is performed so as to satisfy the following formula (1). 0 · 3 SA / B $ 7 ··· (" In addition, in order to obtain the dephosphorization reaction efficiency of the south, the meal chain agent blown to the surface of the molten pig iron bath was changed to C a 0 supply rate b (kg / mi η / molten pig iron ton), and the supply rate of oxygen to the molten pig iron bath molten iron t on) are preferably dephosphorized by satisfying the following formula (2). 1. 2 ^ A / B ^ 2. 5 ... (2) According to the review by the present inventors, it was confirmed that the method of blowing oxygen and refining agent to the molten pig iron bath surface, through the supply rate of oxygen and CaO The supply rate of (refining agent) changes the dephosphorization reaction. Specifically, Fe0 is generated in the molten pig iron bath surface area where oxygen is supplied, and there is a preferable supply rate of CaO in accordance with the generated amount. Here, in the ratio of oxygen to speed, if the supply rate of oxygen is too small, "0" in accordance with the supply amount of Ca0 is not generated in the molten pig iron bath surface area where oxygen is supplied, so CaO slagging is not performed (CaO -FeO-based melt generation), Ca0 still exists as non-slagging, and cannot effectively effect defilling. On the other hand, if the oxygen supply rate is too large, it is necessary for dephosphorization relative to the oxygen supply amount. Ca0 is insufficient, and in this case, Ca0-Fe0-based melts cannot be sufficiently formed. Therefore, in any case, the conditions for the dephosphorization of molten pig iron through the above-mentioned dephosphorization reaction mechanism are favorable conditions. There is a tendency that a high dephosphorization rate cannot be obtained. In addition, if the supply rate of oxygen is too large, the amount of ineffective oxygen other than oxygen necessary for dephosphorization increases and it is consumed for decarburization, so the heat of the subsequent steps is

91119784.ptd Page 29 550295 V. Description of the invention (23) Insufficient sources have led to a significant increase in the operation cost of the decarbonization process. Here, if the above A / B is less than 0.3, the CaO supply amount is excessive relative to the oxygen supply amount. Therefore, in the molten pig iron bath surface area where oxygen is supplied, there is no " Shenglicheng Fe0 in proportion to the CaO supply amount. Therefore, the supplied Ca0 and beneficial method fully carry out slagging (Ca0-Fe0-based melt generation), Ca0 still exists as an unslagging type and cannot effectively affect dephosphorization, so it has a reduced dephosphorization rate. The tendency. On the other hand, if A / B exceeds 7, the necessary Ca0 in phosphorus is insufficient with respect to the oxygen supply amount. In this case, the Ca0-based melt is not used to reduce the dephosphorization rate. The tendency. In addition, by making A / B in the range of 1.2 to 2.5, the balance between the amount of oxygen produced and the amount of CaO supplied can be made to #R ^ ㈣ reaction ㈣ Qianheng is more optimized, and especially The second embodiment that can obtain high cost is to use a pot type or torpedo type container to carry out =: phosphorus $ method, at the dephosphorization place where the pot type or torpedo type refining container is used. A part of the refining agent is blown to the two sides of iron and iron, and the gas limb containing the plate is blown into the molten pig iron by immersion spraying and / or blowing into the nozzle. Gu Ϊ ΐ 2 ΐ and others reviewed the methods of using steel or torpedo models for refining vessels to remove pig iron. The results confirmed that the oxygen and refining agents were blown to the surface of the molten pig iron bath. And the method of blowing into the molten pig iron by dipping the rolling body with tertiary limbs is effective. two,? The amount of L. lactiformis (acid delivery amount) blown by the upper blowing spray gun on the molten pig iron bath surface in the application of Form 11 is 0.7Nm3 / min / melted pig iron tOn or less.

Page 30 550295 V. Description of the invention (24) '1 ΐ 二 ΐ ί t The amount of acid delivered by blowing up and rushing is excessive, so it is feared that the fine n will melt out due to slag. By making the amount of acid delivered from the top-blowing blast to be below π- ~ 'combined pig iron, the slag suppresses foaming, and the son-in-law does nothing. In the embodiment, in addition to the above, the refining agent is blown to the melt by the above blowing spray gun, and the refining agent is injected into the bath and the amount of the refining agent is injected into the bath. i :: = Beam amount% or more. If the above blowing and blowing ratio is%, if the proportion of refining agent and / or Λ-agent is lower than 80% of the total mass, the promotion effect of the reaction will reach the dephosphorization caused by dissolving the pig iron bath surface, and the result will tend to decrease. Fig. 4 is the result of the refining, blasting and blasting according to the present invention, showing the P content maintained through the ratio of the necessary stone to the total amount of refining agent. The test is for molten pig iron in a pot-shaped container (15〇ton), I.11% by mass, Sl content: 0.07% by mass with a gas refining agent crude 5 ~ 5. 〇Nm3 / molten pig iron _] do For the ton), blow the powder from the top ^ = the following lime powder (0 ~ "Blow into the powder with molten pig iron, thresh the pig iron bath surface, and pour the powder into the powder through treatment Time: 15 minutes). All remaining necessary 2] ^ kg / min required for use through immersion. One part of this powder or (Fe content 40% by mass) formula Λ ', and the insufficient part is the use of dust without adding CaF2 = Powder. In this destructuring process, below the refining agent. Let the blow rate to the volume of the melted volume after 'Rong Huan Bu ^ be 20kg / dissolved pig iron.

91119784.ptd Page 31 550295 V. Description of the invention (25) B (kg / min / melting pig iron ton), and the supply rate of ACNmVnun / melting pig iron, the amount of oxygen added is to make the following formula and ⑷7 is 2 .〇. Lime dissolved pig iron ton) and the amount of lime WCa〇Si (kg / lime amount kao—PUg /. In addition, oxygen is used as the carrier pig iron—the depth of the depression L generated on the total pig iron bath surface. Refining and refining, the melting is controlled within the range of 200 ~ 500mni. The L value of the right factory is) the temperature of the pig iron is 13, the war. Department; the dissolution before and after: ash and slag Let the Ca0 concentration (slag content: ::?). The amount of lime necessary to make the processed molten pig iron equal to or less than ^ 舁 舁% in the processed slag is shown in Figure 14. 3 is 0 · 0 2 In Figure 4, it is reduced according to the increase in the proportion of the refining dose through blowing up. "= = The proportion of fine mass or more can be made, the lime, and especially the gas is blown in together. For example, lime powder can be used, and there is no particular limitation on the type of m powder. What happens in the iron plant;: ;;: =; =, conversion furnace grate & 'Γ powder is the main body of powder, and other powders are equal to-=. In the case of using π >, the refining agent is to dissolve 2: when it is used as the powder refining agent, When it floats on the surface, it promotes heating during the mid-ocean period, and is used to dissolve raw materials. It is used for melting and melting of slag. C Pig iron is used for cold noodles. That is, the dust generated in the factory can be discarded. On the right, 'dust is powdery, so in order to recycle it, it is beneficial -_ In the past, 911919784.ptd page 32, 550295 V. Description of the invention (26) The ease of operation must be briquetted The state does not require the briquette-like formalities. But it is for the purpose. Also, the bismuth with a carbon source as the main body lays down ^ i as the M powder is sold again, and the powder with the carbon source as the main body is the next step. It becomes effective heat and :: / Pig iron plus CaMg (C〇3) 2 and other powders are dissolved pig iron Ca ^ 'Ca (0H) 2 (c〇2, 〇), and this gas has Zhongzi, ,,, and 7 knife solution and the strong stirring of CaO generated by thermal decomposition occurs, and the iron alloy can also be added into the Na, /, "T as the organic carbon chain step agent The iron oxide powder is part of the fish sculpting U η and Τ in the pig iron bath. They are also part of the lice source. Sword beans are blown together to melt the special PP to the gas in the pig iron (carrier gas @ 1: Another limitation, the type of oxygen (pure flying T) can be used and there are no inert eagle carvings, β 礼 Λ As s milk disorder body), Ν2 and ^ tower + ά, 脰 special. ^, Chinese and oxygen blowing When the refining agent is added, it can be expected to dissolve 砼 钟 n + J ^ to be promoted by the so-called transitory reaction of 沣 日 可. It is important to Dan Dan Geng. However, because of robbing and blowing into the tube by immersion Oxygen is supplied from the mouth, and FeO is generated at the tip of the nozzle, so that the life of the spray nozzle and the nozzle has a long life. In contrast, in the case of using inert gases such as krypton and Ar, the reaction surface can not be expected. , But the life of the spray gun and nozzle is longer than the use of oxygen and gas. Therefore, the type of gas to be used may be selected in consideration of the entire cost including spraying and humiliation. As the means for blowing the refining agent into the molten pig iron, an immersion spray gun, a blowing nozzle provided in a chain container, or both can be used. For the blow-in nozzle, any type of nozzle such as a bottom nozzle and a horizontal nozzle can be used. a 'In this second embodiment, substantially the entire amount of the refining agent is blown through the upper mouth to the molten pig iron bath surface, and is added by immersion spraying and / or blowing into the molten pig iron to be added to the molten pig iron. Refining agent robbed by blowing up can

91 ”9784 • Ptd Page 33 550295 V. Description of the invention (27) _ The added amount is all the refining agent, the daily spray gun is blown to the molten pig iron, and the amount of 20% to 80% by mass of D is better. If the proportion of the refining agent exceeds 80% by mass, if the proportion of the refining agent exceeds the total amount of the refining agent, less than 20% by mass of Chuantutu / 5 should be used for the necessary mixing power, and the above-mentioned chain of promoting cleansing fruit should be formed / \ Blowing to the molten pig iron bath surface Figure 5 is for permeation—up = fruit // cadmium volume, and through the impregnation spray% pair, the synthetic pig iron bath surface blowing refining agent .. #. ^; III: f " " " The amount of refining agent added by over-blowing and spraying relative to Ξchain two = Example of the effect of μ and β, and the relationship between β and 不, which is the ratio of adding 里. In this test, for the pot Type ρ content maintained by U5_r〇: 〇1〇 ～ 〇11 mass γ 〇, 〇7% by mass of molten pig iron, using oxygen (4.5 4.0 ^ / 3 dissolved pig iron ton) as the carrier gas will The particle size of the refining agent (contains the main pig iron ton) is blown from the upper blowing spray gun to the molten pig iron bath 2 and the remaining necessary lime is grabbed by reverse > shell spray. Partially (0 ~ 6kg / melted pig iron ton) can be dephosphorized (blown time · 15 minutes). This desiliconization treatment is not added to the refining agent, and the slag amount after the treatment is n 20kg / melt Below pig iron t〇n. Supply rate of lime B (kg / mi η / molten pig iron t 〇n) blown to the molten pig iron bath surface, and supply rate A (Nm3 / min / melt) of oxygen blown to the molten pig iron bath surface The ratio A / B of pig iron ton is 2 0. The amount of lime added is such that the amount of lime Wcao — P (kg / melted pig iron ton) and the amount of lime Wcao — Si (kg) are specified in formulas (5) and (6) described later. / Molten pig iron ton) in the total range. In addition, oxygen is used as a carrier gas for blowing and refining.

91119784.ptd Page 34 550295 V. Description of the invention (28) The depression depth L (later, meaning L value) generated by the molten pig iron bath surface is controlled within the range of 2000 ~ 500 mm. Also: the melting pig iron temperature before and after the theorem of formula (7) is 丨 3 0 0 ~; [3 2 0 ° c. The place = "dephosphorization place" is calculated from the amount of lime added and the concentration of 2Ca0 in the slag (the balance of the amount of slag after the treatment. ~, Check the analysis value). The proportion of the total amount of the refining agent added to the denier chain agent is less than 20% by mass. In the refined region, the dephosphorization effect is greatly reduced. Fig. Δ showing the mass percentage is shown in the example of the present embodiment when it is performed and treated in a blast furnace dephosphorization facility. According to the pig iron from the blast furnace, S 1 in the scale iron contains s, and if necessary, it can be desiliconized in a casting bed 'before the dephosphorization treatment. The dephosphorization treatment is to blast the blast furnace 5 into the blast furnace pot 4 to dissolve molten pig iron, such as molten pig iron, and inject the lime powder (refining agent). Refining agent) Blow to melted pigs. The feed rate of the injected lime powder is to stir the melted pig iron: A sufficient third embodiment is to make the degree of refining and the supply rate of oxygen blown to the bath of molten pig iron satisfy the following ( 3) and (4) ϋ = dephosphorization treatment. You enter the lamp (Cl / Dl) XC2 / D2) ... (3) C1 > C2 ... (4) But C1 · average value of the refining agent supply rate converted to CaO in the early stage of dephosphorization treatment (kg / m in / melting pig iron ton) C2: Refining agent supply rate converted to CaO in the later stage of descaling treatment

550295

Average value (kg / mi η / dissolved pig iron ton) D1: average value of oxygen supply rate in the early stage of dephosphorization (Nm3 / min / dissolved pig iron ton) D2: average value of oxygen supply rate in the late stage of dephosphorization (Nm3 / min / dissolved pig iron (ton) The content of P in pig iron is refined and processed to become the filling in the dross slag (p). After the treatment, the movement of the molten pig to the reaction site will become a refining form that will effectively participate in dephosphorization. Ratio of molten pig iron bath surface (refining agent supply rate / oxygen is added at the later stage of descaling treatment relative to the amount of refining agent added before descaling treatment. In order to increase the supply rate of the dissolving agent, the dephosphorization rate can be moved. In the rate region, relatively, the content of P in de-ironization becomes lower, and the [p] constant-rate step in the metal is reduced compared to the pre-dephosphorization treatment. Therefore, the supply rate of the refining agent and oxygen specially supplied as described above is reduced. (Supply speed) and refining agent supply speed, the smaller the early stage of dephosphorization treatment, the less efficient the dephosphorization treatment. In the method of the present invention, the reactivity of the refining agent is effectively improved based on the foregoing reasons. Therefore, the necessary minimum refining agent is added at the later stage of the dephosphorization treatment and the effective dephosphorization treatment is performed. FIG. 7 shows that in a reformer-type decompression refining furnace (300 ton), without adding ca dagger, dephosphorization treatment was performed under the following conditions (1) and (2), and the concentration of dissolved pig iron after dephosphorization treatment was investigated. It is necessary for the P content to be 0.0012% by mass (the relationship between the original unit and the dephosphorization efficiency. ① The refining agent blown to the surface of the molten pig iron bath is converted into a supply rate C (kg / min / melted pig iron) t〇n) is fixed throughout the treatment period, and

91119784.ptd Page 36 550295

550295 5. Description of the invention (31) 'The content of P in pig iron is 0 · 10 ~ 0Π% by mass, and the content of Si is less than 07% by mass. The refining agent is calcined lime that does not contain CaF2 and is mainly composed of CaO. The oxygen source mainly uses oxygen, which is blown from the top to the molten pig iron bath surface, and a part of it is a solid acid source (iron ore) added in combination. The supply amount of the refining agent is 4.6 to 9.0 kg / dissolved pig iron ton, and the supply amount of oxygen is 8.6 to 13.6 N m3 / dissolved pig iron ton. Regarding the unfilling treatment of (1), the C / D was set to be 0.50 to 0.69 kg / Nm3. Regarding the dephosphorization treatment of ②, let ci be 0.88 ~ 1.0kg / min / molten pig iron ton, C2 0.30 ~ (K39kg / min / molten pig iron ton, C1 / D1 0.60 ~ 0.83kg / Nm3, C2 / D2 is 0.38 to 0.48kg / Nm3, (C1 / Dl) x 56 to 72% = (C2 / D2). In addition, the dazzling amount after treatment is 20kg / dissolved pig iron ton. Lime The amount of addition is such that the amount of lime wca0-p (kg / dissolved pig iron ton) and the amount of lime Wcao-Si (kg / dissolved pig iron ton) specified in the formulae (5) and (6) (i) described later fall within the total range. In addition, the refining agent is blown by using oxygen as a carrier gas, and the depression depth L (the value of L defined by the formula (7) described later) generated on the surface of the molten pig iron bath is controlled to be within a range of 200 to 50 mm. In addition, the molten pig iron temperature before and after the dephosphorization treatment is 1 3 0 ~ 1 3 2 0 ° C. The amount of dross after treatment is determined by the amount of lime added and the CaO concentration in the slag (analyzed value of the slag). Calculate the mass balance. According to Figure 7, it can be seen that the dephosphorization treatment of ② is less than that of ①, and the unit of Ca0 is less and the dephosphorization efficiency is higher. The reason is that the condition of ② was not used in the later stage of refining. Carry on In the third embodiment, the refining agent supply rate and oxygen supply rate are (C1 / D1) > (C2 / D2), Cl > C2 can achieve the desired effect, especially

91119784.ptd Page 38 550295 V. Description of the invention (32) The range of (Cl / Dl) x 30 ~ 80% = (C2 / D2), Clx 30 ~ 80% = C2 is preferable. In (Cl / Dl) 3 0% > (C2 / D2), Cl X 3 0% > C2, due to insufficient supply of refining agent, there is a tendency to reduce the dephosphorization rate. On the other hand, in ( Cl / Dl) X 80% < (C2 / D2), Cl X 8 0% < C2, the excess refining agent supply in the later stage of dephosphorization treatment increases, so it tends to reduce the descaling efficiency. In this third embodiment, the refining agent and oxygen may be supplied during the dephosphorization treatment (before and after the dephosphorization treatment) according to the above conditions. Therefore, the form in which the refining agent supply rate and the oxygen supply rate are changed is arbitrary. It can be changed continuously or in stages or in these two forms. In a fourth embodiment of the present invention, for molten pig iron having a Si content of 0.15 mass% or less, oxygen and at least a part of the refining agent are blown onto the molten pig iron bath surface by a blow-up spray, and dephosphorization treatment is performed, and here In the dephosphorization treatment, the amount of lime Wca0-p (kg / dissolved pig iron ton) obtained by the following formula (5) and the amount of lime Wca0-Si ( kg / dissolved pig iron (ton)) A total amount of lime is added as a refining agent.

Wca0-P = (Dissolved pig iron [P]-Target [P]) X (1 0/62) X 56 X 3 / η Cao-(5) But / grain pig iron [P]: Melting before dephosphorization The concentration of P in pig iron (% by mass) and [P] · The target concentration of p in molten pig iron after the bowl removal treatment (% by mass) 々cao (lime efficiency> 5 · 1 to 5 Wca〇-Sl Dissolved pig iron [Si] X (10/28) X 56 X 2

91119784.ptd Page 39 550295 V. Description of the invention (33) '一 " * ---- But dissolved pig iron [Si]: Si concentration, degree (mass%) in molten pig iron before dephosphorization treatment, such as W As mentioned above, the previous dephosphorization treatment technology is based on the premise that the slag is maintained uniform = liquid state, and the slag amount is determined according to the phosphorus distribution Lp. Therefore, the necessary refining amount must be fixed with 7 P and S i. Refining agent in the above amount. In contrast, the present invention uses the direct dephosphorization reaction in the molten pig iron bath surface area centered on the fire point and the P-fixation mechanism of the solid-phase main slag in the outer area, so it can be used as necessary as described above. At the lowest dose of ugly essence, it can produce dephosphorization reaction efficiently. The amount of lime consumed by Kaijima 'to fix the P and S i in the molten pig iron can be calculated by the following formula. In the following formula, Wca〇-p〇 is the amount of lime consumed in the fixed molten pig iron (kg / dissolved pig iron ton), and Wcao-Si〇 is the amount of lime consumed in the fixed > Si in the refined pig iron (kg / Dissolve pig iron (ton).

Wca〇— P〇 = (melted pig iron [p] — target [ρ]) χ (1〇 / 62) χ 56 but molten pig iron [ρ]: ρ content (mass%) in molten pig iron before defilling treatment [P]: P content in the molten pig iron after the dephosphorization treatment of the target (mass%)

Wcao-Sio = Dissolved pig iron [Si] X (1 0/2 8) X 5 6 X 2 But> Valley pig iron [S i]. The content of Si in molten pig iron treated by destone processing (mass%) This If the total amount of lime added is Total Ca0 (kg / dissolved pig iron), the lime efficiency π ca0 that participates in dephosphorization is calculated as follows. 7? Cao: = Wcao_Po / (Total CaO ~ Wcao_Sio)

9] n9784.ptd Page 40 550295 V. Description of the invention (34) " ~-In this embodiment, first, the lime efficiency θ ca〇 is defined as 0.5 · 1 ~ 1. This; the lower limit of 7 cao is defined by the viewpoint that the addition of unwanted lime does not proceed and that the dephosphorization reaction which is the object of the present invention is appropriately generated. That is, if π ca0 is less than 0 · 5, useless lime addition is substantially performed, and not only the effect of the present invention for performing effective dephosphorization treatment with a small amount of refining agent added is lost, because the specified oxygen source unit The relative amount of lime ^ added to Fe0 produced below is excessive, so it becomes a large amount that cannot be slagged (^ 〇, such non-slagged CaO is to hinder the above-mentioned dephosphorization reaction. Therefore, 'this implementation In the aspect, the amount of lime Wcao — P (kg / dissolved pig iron ton) obtained by the following formula (5) and the amount of lime obtained by the following formula (6)

Wcao-Si (kg / > pig pig iron ton) was added with a total amount of lime to perform a stone removing treatment.

Wcao — Ρ: (Melted pig iron [p target [P]) X (; [〇 / 62) χ 56 χ 3/7] ca〇 " * (5) but molten pig iron [p]: Content of p in molten pig iron (% by mass) Target [P]: Target P content of molten pig iron after dephosphorization treatment (% by mass) 7? Cao (lime efficiency) =: 0.5 · 1

Wcao — Si: dissolved pig iron [si] X (10/28) X 56 X 2 ". (6) but dissolved pig iron [S i]: s 丨 content (mass%) in molten pig iron before dephosphorization treatment Wcao-P is the amount of lime necessary to fix p in the molten pig iron to 3CaO · P205 when π cao = 0.5 to 1

91119784.ptd Page 41 550295 V. Description of the invention (35) The amount of lime necessary for fixing Si in pig iron to 2Ca0 · Si 〇2. FIG. 8 is a case where the molten pig iron having a P content of 0.11% by mass is de-filled to a p content of 0.15 mass%. In this embodiment, lime added based on the Si content in the molten pig iron is added. The amount is compared with the amount of lime added in the previous method of disc removal treatment. Wca0-Si is the amount of lime necessary to fix S i, and Wcao-P1 is fixed at 7? Cao = l. The amount of lime necessary for use), Wcao-P0.5 is the amount of lime necessary for P to be fixed at πca0 = 0.5, and W is the amount of lime added in the previous method. As shown in the figure, the necessary amount of lime in the previous method is determined according to the phosphorus distribution Lp and the necessary amount of slag. Therefore, it has nothing to do with the concentration of Si in the molten pig iron. The amount of lime added in this embodiment is [Wcao — Si + Wcao — Pjqwcao — Si + Wcao — P 0.5.] Is sufficient, and the amount of lime added can be greatly reduced compared to the previous method. 9 is a diagram showing the relationship between the amount of lime and the lime content cao necessary for de-p removal in this embodiment and the previous method, and the p content in the molten pig iron after the dephosphorization treatment. The necessary amount of lime is referred to as [W-Wcao-Si] in FIG. 8. According to FIG. 9, it can be seen that this embodiment uses less lime for P removal than the previous method and performs defilling / treatment at a high lime efficiency. In this fourth embodiment, the amount of lime Wcao ~ p (Wcao-P determined by π ca0 = 丨, the same applies hereinafter) It is preferable that 80% by mass or more of lime is blown to the molten pig iron bath surface through an upper blowing spray gun. Fig. 10 shows the results of tests performed by the inventors and others according to the present invention. The results show the ratio of the amount of lime X and the amount of lime Wcao-P blown to the molten pig iron by the upper blowing lance X / Wcao-P After disc processing

550295 V. Description of the invention (36) Relationship of P content in pig iron 'This test is the p content maintained for the conversion furnace type (34oton): 0095 ~ 〇135 quality dissolved pig iron, oxygen (1 (W5NmV molten pig iron: is the lime powder with a particle size of 1 mm or less for the rolled body of the carrier (4 ~ 10kg / melt, 0 = sprayed from the upper person to the molten pig iron bath surface, dephosphorization treatment 燐 m "1) v4 minutes), the molten pig iron is loaded into the conversion for decarburization: calcium thorium blowing chain. In the dephosphorization process, the amount of CaF2 added is 丨 kg / melt or less, and the slag amount after the treatment is 30kg / melt pig iron ton. The ratio of the supply rate of lime of the molten pig iron bath surface B (5 kg / mi to the melting standard a on) and the supply rate of oxygen blown to the molten pig iron bath surface is cut off (2, n? Combined pig iron ton). / β is i7. In addition, the depth of the depression 2 generated on the molten pig iron bath surface using oxygen as the radon refining agent is controlled to be within the range of 200 to 500 mm. The temperature of molten pig iron before and after dephosphorization treatment is 1 3 00 ～~ 3 2 〇ί / " The amount of slag after treatment is based on the amount of lime added and Ca in the slag 〇Calculate the mass balance of the concentration (analysis value of dissolving slag). F According to FIG. 10, if the above-mentioned amount of lime in the amount of lime Wca0-p is less than 80% by mass, the disc removal rate tends to decrease. The reason is that the high reaction efficiency as described above is relatively difficult to obtain when the refining radon is directly put into the fire point of the corresponding part or the oxygen supply area near it. It also burns than C and Fe and melts in the blowing chain. Pig iron exists in the form of SiO2, so it does not necessarily react with lime at the fire point. Therefore, the source of lime that is equivalent to the amount of lime Wcao_Si that is fixed to SiO2 is not limited to burnt lime. Free Ume) * quality.

550295

V. Description of the invention (37) This ‘equivalent to lime’ and a refining agent consisting of burnt lime and lumped lime may be used as lime powder or lumps. Ironmaking: = Select a smelting slag from ironmaking slag containing unreacted Ca0 (production inspection 3 4 72 can also use a conversion furnace that occurs during the decarburization step. Hot metal bag ^ check and so on. The amount of addition is taken from α Gu Er, according to the reasons stated, in order to reduce the content of refining agent is 0 1 5:. The dephosphorization efficiency is the S soil that dissolves pig iron in dephosphorization treatment] · 03 mass ^ 7 shells / ° = lower, preferably 0.07 mass% or less, and more preferably thinner per I ... / melting pig iron . If the content exceeds 0.15% by mass, the effect of reducing the amount of refining agent added to Diyu i is reduced. In the form of oxygen application, the refining agent, which is defined by the following formula (7), is blown with oxygen or concave as the carrier gas, and the refining agent is blown on the surface of the molten pig iron bath. The degree L is controlled to 200. ~ 500mni. ^ L〇X exPi (-〇.78x Lh) / L〇} ... (7) ° " 63 x {(F02 / n) / dt} 2/3 mm) F〇2: Oxygen supply speed (Nm3 / hr) from the top blow nozzle η: Nozzle hole number of the upper blow gun 4 · Nozzle hole control (mm) of the upper blow nozzle (mm) (but, multiple When the nozzle diameter of the nozzle hole is different, it is the average hole diameter of the entire nozzle hole.) The dephosphorization reaction mechanism targeted by the invention is designed to reduce the efficiency of dephosphorization by adding less refining agent, and in particular, to supply oxygen to the reaction. Part of the fire: dissolve the slabs * k cut, specifically, blow oxygen or oxygen and refining agents in reverse-the depth of the depression generated by the surface of the pig iron

550295 V. Description of the invention (38) The composition of the spray gun and the theoretical depression depth calculated from the use conditions are preferably controlled in the optimal range. Here, if the depth of the depression generated by blowing oxygen or oxygen and refining agent on the molten pig iron bath surface is too small, that is, the blowing of oxygen or oxygen and refining agent is too weak, slag foaming occurs outside the fire point, and this foaming The slag is to hinder the flow of the injected oxygen, so the supply of oxygen to the fire point is reduced, which becomes an unfavorable condition for improving the dephosphorization efficiency. In addition, because the supply of oxygen to the ignition point is unstable, the oxygen necessary for dephosphorization cannot be stably supplied, the deviation of the dephosphorization efficiency becomes large, and 3 C a 0 · P2 05 is decomposed and restored to fill. On the other hand, if the depth of the depression generated by blowing oxygen or oxygen and refining agent on the surface of the molten pig iron is too large, that is, the blowing of oxygen or oxygen and refining agent is too strong, the oxygen density in the fire point is too high, corresponding to The P of FeO generated cannot be fully supplied by the metal. As a result, decarburization is carried out due to an excess of F e 0, which is also a disadvantageous condition for improving dephosphorization efficiency. The depression depth L generated on the molten pig iron bath surface by blowing oxygen or blowing a refining agent using oxygen as a carrier gas can be defined according to the following formula (7). L = L0x exp {(-0.78x Lh) / L0} --- (7) L0 = 63 x {(F02 / n) / dt} 2/3 but LH: the height of the spray blast (mm) F02: Oxygen supply speed from upper blow spray (Nm3 / hr) η: Nozzle hole number of upper blow gun dt: Nozzle hole diameter (mm) of upper blow gun (however, multiple nozzle hole nozzles When the diameter is different, it is the average hole of all nozzle holes

91119784.ptd Page 45 550295

V. Description of the invention (39) f Implementation shape ㈣ 'The above-mentioned depression depth of the molten pig iron bath surface is 200 to 500 mm and the stone removal treatment is performed. Fig. 11 Rabbit 钿 This work ❺ According to the inventor's operator = order test ^, the result 'not out / pit depth L of the pig iron bath surface and the efficiency of the dish removal and the molten pig iron after defilling treatment ☆ 里 关 {糸, j dagger formula is the p content of the furnace type container (3 4 0 t ο η) · χ 〇 · 0 9 5 ~ 0 · 135 mass%, Si content: 〇. 〇2 〇〇〇〇〇—, the oxygen U0 ~ 15Nmv dissolved pig iron (ton) as the gas valley secondary agent particle size of less than 1 dragon lime powder (4 ~ 10kg / melted pig iron t0n) from top blowing to blowing to melt The pig iron bath surface is subjected to dephosphorization treatment (processing time · 08 minutes), and then the molten pig iron is charged into a decarburization conversion furnace and subjected to decarburization blown knife breaking treatment. The amount of Cah added is 1 kg / melted pig iron. Hereinafter, the amount of slag after Lu Li is 3 Okg / melted pig iron ton or less. The supply rate of lime blown to the molten pig bath (kg / min / melted pig iron ton), and the supply rate of oxygen blown to the bath surface of molten pig iron (Nm3 / mi η / melted pig iron ton). The ratio A / B is 1.7. The amount of lime added is within the range of the sum of the stone ash amount Wcao-P (kg / melt pig iron ton) and the lime amount Wca0-Si (kg / melt pig iron ton) specified in the formulas (5) and (6). In addition, the thawing temperature before and after the dephosphorization treatment is 1 3 0 to 1 3 20 t. The amount of slag after the treatment is calculated from the mass balance of the CaO concentration of the added lime and the analytical value of the dissolved slag. /. According to FIGS. 11 (a) and (b), the depression depth L is compared with the range of 2000 to 500 mm, and in the range of less than 2000 mm and more than 500 mm, according to The reason is that the dephosphorization efficiency becomes low, and the p content in the molten pig iron after treatment tends to become higher. &

550295 V. Description of the invention (40) The sixth embodiment of the present invention is for the following, preferably 0.07 mass% or less, more preferably 0.003 mass center / two: Add rgCaF2 to the amount of 1 kg / Dissolve pig iron below t0n • Essentially, make sure to add the unavoidable miscellaneous substances contained in the refining agent. 7 Under the condition of ice calling, blow oxygen and at least one or two shells through the blowing blow gun to the molten pig iron bath. On the other hand, the melting pig iron temperature at the end of dephosphorization is 136 ° t to 145 (Kc. Π dephosphorization treatment, because the dephosphorization reaction is an oxidation reaction of P, so the past; the temperature is lower is more favorable, In the high biochemical Shangguang: advanced treatment: the phosphorus from the slag to the metal will be phosphorus reset. Therefore ,: in the high temperature region above 1 360 ° C dephosphorization treatment, the P content in iron is reduced to a relatively low level. In the present invention, the inventors, etc., chemically dissolve si :: in the pig iron by the dephosphorization treatment in the method of the present invention, and remove it with the condition that the amount of caF2 is small or no addition τ is low, even if it is subjected to high temperature treatment It is almost impossible for phosphorus to migrate from the metal to the second position of the metal, and: high dephosphorization Response efficiency. Even if such high-temperature treatment can reduce the rate of phosphorus compounding, in the method of the present invention, because the refining agent is supplied by oxygen to the molten pig iron bath surface area where a large amount of FeO is generated, it is the same as the method of loading a block of lime. By comparison, the area of contact between CaO (refining agent) and Fe0 has greatly increased, so the oxidation of FeO through FeO ~ and ^. The efficiency of the reaction and 'the speed field also becomes larger' shortens the CaO-FeO system melting Body melting time. That is, the descaling reaction is completed instantaneously, and the subsequent melting time of the slag is short, so the speed of phosphorus reset is also small. Figure 12 shows that no "dagger" is added to the conversion furnace container (300 ton). Under the conditions

V. Description of the invention (41) '---------- The dephosphorization treatment of molten pig iron, the temperature of molten pig iron at the end) and the content of phosphorus removal efficiency Indication ⑽ ▲ n lime efficiency). In addition, the efficiency of lime in Fig. 12 is relative to the addition of Ϊ ^ ^ ^ ^ ^, ^ ^ ^ ^ ^ 3CaO-P2005 ^ It is just mentioned that it is derived from stoichiometry. ^: Type test Ί Furnace melted pig iron, if necessary, perform desulfurization in scale beds and melted pig iron pots. I 'desulfurize in' grained pig iron steel ', and use this melted pig to transform into a furnace-type vessel for dephosphorization. At this time, the S1 content of the dephosphorized / combined pig iron and the temperature of the molten pig iron after the treatment were changed in various ways. The p content in the molten pig iron before the dephosphorization treatment was 0.1 · 10 ~ 〇. U mass / 〇_ S 丨 content was 0.15% by mass, and the p content in the molten pig iron was decomposed by the dephosphorization treatment. %the following. The refining agent is calcined lime that does not contain CaF2 and is mainly composed of CaO. The oxygen source is mainly oxygen, which is blown from the top to the molten pig iron / valley surface for addition, and part of it is combined with the addition of solid acid source (iron ore). The amount of oxygen other than desilication is controlled to 10 ~ The range of 11NmV dissolves pig iron ton. In addition, the time of the de-filling treatment is 10 to 11 minutes, the temperature of the molten pig iron before the de-tasseling treatment and the amount of waste iron are adjusted, and the temperature of the molten pig iron after the de-filling treatment is controlled. The amount of slag after treatment is 30 kg / ton of molten pig iron. In Figure 12, 0 is the test example (a) in which the above is charged with added lime and the molten pig iron temperature at the end of the dephosphorization treatment is 1 26 0 to 1 350 ° C. ▲ is the above Oxygen is used as a carrier gas to blow lime (lime powder with a particle diameter of 1 mm or less) to the surface of the molten pig iron bath, and the molten pig iron temperature at the end of the dephosphorization treatment is

91119784.ptd Page 48 550295

UMMWOT: Test example (b). The amount of lime to be added varies according to the Si content in the molten pig iron in the range of 5 to 10 kg / melt pig iron ton. In test example (b), the supply rate B (kg / min / melt pig iron) of lime blown onto the molten pig iron bath surface and the supply rate A (Nm3 / min / The ratio A / B of molten pig iron (ton) is 17 and the addition of lime is the amount of lime specified in the formulas (5) and (6).

Wcao_P (kg / dissolved pig iron ton) and the amount of lime Wca0-Si (kg / dissolved pig iron ton) in the total range. In addition, the depression depth L (the value of L defined by the above-mentioned (7) formula) generated by blowing the fine chain agent 'on the molten pig iron bath surface by blowing oxygen as a carrier gas is controlled within a range of 200 to 500 mm. The amount of slag after the treatment is calculated from the mass balance of the CaO concentration of the added lime and the analysis value of the slag. 'According to Figure 12, regardless of the lime supply method and the temperature of the molten pig iron at the end of the dephosphorization treatment, the lower the Si content in the molten pig iron, the lower the ratio of CaO consumed to 2CaO · Si 〇? Phosphate-lime efficiency increases, compared with the case where the dissolving pig iron temperature at the end of the dephosphorization treatment is 1 2 6 0 to 1 3 5 0 ° C (test example (a)). In the method that lime and oxygen are blown to the molten pig iron bath surface together, the temperature of the molten pig iron at the end of the dissolution treatment is 1360 to 1450 ° C (Test Example (b)) makes the dephosphorization lime more efficient. improve. In addition, such effects are more significant as the content of s i in molten pig iron decreases. The destructuring reaction is more favorable on average at a lower temperature. The results in Figure 12 show that in the test example (b), the reduction rate of phosphorus is reduced by the melting of the slag and the fixation of the dephosphorization products. Figure 13 shows the method of blowing the refining agent and oxygen to the molten pig iron bath surface.

91119784.ptd Page 49 550295

550295 V. Description of the invention (44) ^ Dephosphorization treatment. As described above, in this embodiment, since a high molten pig iron temperature can be ensured at the end of the dephosphorization treatment, sufficient heat sufficient in the subsequent steps can be ensured. In addition, because the molten pig iron temperature after the treatment is high, T. Fe in the slag can be reduced, and the yield of dephosphorized iron is also increased. Generally, the molten pig iron temperature before dephosphorization treatment is about 1 250 to 135 ° C. The method of adjusting the molten pig iron temperature at the end of the dephosphorization treatment is usually to dissolve waste iron and use a converter furnace dephosphorization In the case of the dephosphorization treatment of the refining furnace, a method of suppressing the input amount of scrap iron and the like can be cited. In the case of using a steel container such as molten pig iron steel and dephosphorization treatment of a torpedo car, a method for adjusting the input amount of a solid oxygen source such as sintered powder may be listed. Therefore, it is sufficient to adjust the molten pig iron temperature at the end of the treatment to a range of 316 to 450 by this method. In addition, the specific method for controlling the molten pig iron temperature at the end of the defilling process is to calculate the molten pig iron temperature in the dephosphorization process based on the gas composition analysis value and the exhaust gas temperature of the exhaust gas generated in the dephosphorization process, and control the method according to this For the easiest. That is, in this method, the exhaust gas is subjected to a gas composition analysis to obtain the Cj and C02 concentrations, and the gas production 1 is calculated from the exhaust gas temperature. From this, the amount of heat generated in the furnace can be calculated, and the molten pig iron temperature can be calculated based on this. The seventh embodiment of the present invention is to supply a substance that absorbs heat of molten pig iron through a chemical reaction and / or a thermal decomposition reaction to the molten pig iron bath surface area to which oxygen is supplied. The area of the molten pig iron bath surface where oxygen is blown is the oxygen

550295 V. Description of the invention (45) A large amount of iron oxide is formed, so it becomes a non-amp condition for promoting the slagging of the refining agent. However, on the other hand, high-temperature places are formed by oxidation reaction in the area of the bath surface where oxygen collides ($ is uniquely the fire point). The formation of such high-temperature places is conducive to the melting of lime, but from the viewpoint of unfilling balance Words are bad. … For this kind of problem, the inventors reviewed the countermeasures for the temperature conditions of the molten pig iron bath surface area for oxygen supply, which are favorable for the dephosphorization reaction. The second fruit was that they found that The material that absorbs the heat of molten pig iron through the reaction and / or thermal decomposition reaction is not hindered by oxygen to promote the slagging of the refining agent, and is suitable to suppress the temperature of the molten pig iron bath surface area where oxygen is supplied. Dephosphorization reaction efficiency. It is used to dissolve the pig iron by chemical reaction and / or thermal decomposition reaction: The substance (hereinafter referred to as "endothermic substance") is added to the melted pig iron (supply) to suppress the melting of pig iron. The addition of oxygen, iron, iron, iron, etc. supplied by Wang Gong Iron / Noodles, and the temperature of the cold pig iron increased excessively and added, Li Kong'ao ... 7 must be supplied to the confession of gas-> 'The endothermic substance is necessary. To the molten iron surface area of the mouth where the pores are swollen. 7 Location 仏 — In the area of the molten pig iron bath surface, it is also special. + + 'Your supply ,,' 5 lice in the molten pig iron bath generate the so-called "fire point person spraying and blowing oxygen, and the fire point is sprayed with oxygen gas. Collision; "Air supply is better. In this region, the area stirred by the oxidation reaction of oxygen (Fe0 in the ferrous pig bath surface milk gas injection) is the area concentrated and the effect of the addition of quality. 彳 Ran is to obtain significant endothermic here. If the endothermic substance is a chemical reaction when added to pig iron 550295

5. Description of the invention (46) Either thermal decomposition reaction or both are acceptable, and there is no particular limitation on any of the solids that reduce the heat (endothermic) of pig iron. & This endothermic substance can be a gas, and it can be used as an endothermic substance, oxynitride (NOx), etc., and " version port 丨 a cow such as carbon dioxide, water vaporized heat substance is supplied to the melting peak by Mom uses ", more than one. These gases absorb, for example, C〇2 + Fe—Fe0 + C0, M + Fe—Fe〇fH ^ main inverse f (endothermic heat of iron. As a result, compared to ga 2), this reaction is caused by melting The heat generation makes the total: J = ((Fe + 1/2 〇, decrease. In addition, in the above-mentioned gas and: soil = heat or heat generation occurs in a large amount--M 彳 立 立 and ... material shell, It is also suitable to use the emulsified stone of the King of the Iron Works, the emulsified stone, and the leeches, so it is particularly suitable. =, Plus, the purity of the sexual effect is reduced to some extent, and it is also caused by the removal of :: Therefore, there is no special problem. In addition, the second reason is that the final steelmaking stage '^ C0.DH2 ^, 1 a;-^ ;; "-a ^ ^ has the effect of increasing the energy of exhaust gas; the type of B exhaust gas is recovered, and Also gold: ": solids that are endothermic substances can include carbonates of metals, most oxygenates, especially carbonates of alkaline metals, alkaline earth metals, and hydrogen. More than one kind can be used. These solids The endothermic substance mainly generates a thermal decomposition reaction through the surface of the iron bath, and at this time, it is melted as above, and the CD2 series is generated through thermal decomposition. And this ⑶2 m2o ί. Ί re-acts as an endothermic substance, so Nafn f metal carbonates that can obtain high endothermic effects are particularly caC03, CaMg (C03) 2, MgC03, 3, FeC03, MnC03, NaHC〇3 (carbonic acid Sodium hydroxide), etc., metal hydroxide

91119784.ptd Page 53 550295 Five-Description of the invention (47) ---

Examples of F compounds include Ca (0H) 2, Mg (0H) 2, and β

Fe (〇H) 2, Mn (0Η) π, Ni (〇H) n, etc., and. ) 2, A1 (0h) 3. One or more of these solid endothermic materials may be used. CaMg (C〇3) 2 is not only easily available, but also / C03: Ca (〇H) 2

Ca () 'caused by the fact that this CaO has an optional effect and is generated by the above-mentioned thermal decomposition. In general, these solid endothermic substances have the great advantages of the agent, so it is particularly good. Added in white and stone form. For unburned or semi-fired limestone, and the granules and points of solid heat-absorbing materials: The average particle size of Ϊ is from 5 to the right. Is it impossible to quickly heat the solid heat-absorbing materials? The combination of substances, gas' which-part or all of the pig iron bath surface is used as two endothermic substances (gas and / or solid carved ritual endothermic substances. Version: added by top-blowing and other spraying methods, there is no method Special restrictions: = add (use the solid heat-absorbing material to emit crying) Gu Zhuang's pig iron bath surface, the above set to ensure that the heat-absorbing material is for the temple to be inserted into the temple (specially the "fire point") and milk: milk The supplied molten pig iron 5 VII. Put the fruit on the molten pig iron bath surface t, preferably via a bath: Specially, the above spray blows to supply to the melt: Also, the above endothermic substance is blown and checked to mix the endothermic substance with oxygen (When solid and do not absorb ^ to the molten pig iron bath surface, ① is the carrier gas), from the same quality: love, brother, oxygen to go, 0 will endothermic substances and oxygen through each, " to, synthetic pig iron The side of the bath surface grabs the inside and is inspected by each spray μ Through another gas supply line for each of He + Fo $ private supplied to the bath surface of the iron melt method (hot lean solid up 1

9] l] 9784.ptd page 54 550295 5. Description of the invention (48) Any material may be used for the supply of heat-absorbing material (other than oxygen). From the viewpoint that the endothermic substance is surely supplied to the molten pig iron bath surface area supplied by oxygen, the above-mentioned method ① is preferable, but the above-mentioned method ② can also supply the endothermic substance supplied through a specified spray to the To the molten pig iron bath area where oxygen is supplied through other spray guns. Specifically, for example, a form in which a gas endothermic substance is supplied from a central air-jet port at the front end of the up-blowing lance or a gas other than oxygen is used as a carrier gas and a heat-absorbing substance is supplied, and oxygen is supplied from other air-jet ports around the central air-jet port. Better. As the carrier gas, an inert gas such as N2 * Ar is suitable, and a gas endothermic substance (such as C02) may be used as the carrier gas as described later. In the above method (1), in the plurality of air jets, only a part of the air jets only supplies oxygen, and the other air jets supply oxygen mixed with a heat-absorbing substance (optionally, a refining agent) to the molten pig iron bath surface. Alternatively, in any one of the methods ① and ②, a refining agent may be supplied to a carrier gas or a gas endothermic substance other than oxygen or a heat absorbing substance (gas and / or solid) separately or mixed with it. Melt pig iron bath surface is also available. The endothermic substance (gas and / or solid) or the state where the endothermic substance and the refining agent are mixed with oxygen is supplied to the molten pig iron bath surface through an upper blowing spray, for example, the oxygen supply line (top cover, Some or all of the oxygen flow paths in the piping, spray gun, etc.) are supplied with endothermic substances and mixed with oxygen, that is, the endothermic substances (gas and / or solid) or endothermic substances and refining agents are

91119784.ptd Page 55 550295 V. Description of the invention (49) Use other means of supply other than top-blowing and spraying (for example, other + to the molten pig iron bath surface. Spraying other than top-blowing and spray-rolling if spraying < spraying The gun can also be used to supply powder and granules at specified positions in the furnace. The right side and the right side can be used for sampling and temperature measurement. The side spraying is also cold in the furnace. be usable. In addition, the transmitter and the inflow device can be used without any problems, such as the high-temperature compatibility and the accuracy of the input position. For the problem, it can also be, as described above, the refining agent uses oxygen and other '" of 3 for the molten pig iron bath surface area where oxygen is supplied (projection) 'And directly supplying the endothermic 7-gas in this area effectively promotes the dephosphorization reaction. At this time, using the upper blowing 哙 'can be the most ^ ^ ^ λ = τ to blow oxygen and refining agents and endothermic substances (gas and / or solid) to the molten pig iron bath surface Method, in addition to, for example, the above I. In the case of + multiple jets, some of the jets only use oxygen, and 2 or 2 of the gas ports. If necessary, oxygen or a gas other than oxygen (such as nitrogen and chlorine and other inert gases) is used as the carrier gas. The refining agent and It is also possible to supply endothermic substances (gas @ and # 5 solids) to the molten pig iron bath surface respectively. In addition, in this case, the central part of the front end of the spray gun has a main air outlet, and the surrounding area has a plurality of secondary air outlets to blow and grab. Gases other than the above oxygen are used as the carrier gas to supply the refining agent 2 and the hot substance (gas and / or solid) to the molten pig iron bath surface, respectively. The gas blowing and the refining agent and the heat absorbing material blowing can be performed by using different upper blowing spraying. However, in any case, as described above, the refining agent is slagged most efficiently. The refining agent and the endothermic substance are co-supplied with oxygen.

91119784.ptd 550295 5. Description of the invention (50) The surface of the molten pig iron bath is particularly good. Figs. 14 (a) to (e) are examples showing the supply forms of oxygen, refining agents, and endothermic substances to the molten pig iron bath surface using a top-blow jet. Among them, Fig. 14 (a) is a form in which oxygen and a refining agent and an endothermic substance (gas and / or solid) are mixed and supplied by spraying (blow to the molten pig iron bath surface), and Fig. 14 (b) is a part of The air jet port supplies oxygen and refining agent, and other air jet ports supply oxygen and endothermic substances (gas and / or solid) respectively (blow to the molten pig iron bath surface). Figure 1 4 (c) Carrier gas and refining agent other than oxygen, and oxygen and endothermic substances (gas and / or solid) are supplied (blow to molten pig iron bath surface) separately from other air jets. Figure 1 4 (d) The gas endothermic substance and refining agent, and the oxygen and endothermic substances (gas and / or solid) are separately supplied (blow to the molten pig iron bath surface) from other air outlets. Figure 14 (e) shows the oxygen and Refining agent, the form in which gas endothermic substance or gas endothermic substance and solid endothermic substance are separately supplied (blow to the surface of molten pig iron bath) from other air outlets. However, the supply forms of oxygen, refining agents and endothermic substances to the molten pig iron bath surface are not limited to this. As described above, in the solid endothermic substance, CaC03, Ca (OH) 2, and CaMg (C03) 2 are used to generate CaO through thermal decomposition, and this CaO has a function as a refining agent. Therefore, this embodiment is to supply the solid An endothermic substance can replace part or all of the CaO-based refining agent (mainly quicklime), and the CaO generated by this substance can be used as a substantial refining agent for dephosphorization treatment. That is, in this case, at least one selected from the group consisting of CaC03, Ca (0H) 2, and CaMg (C03) 2 (hereinafter referred to as "hereinafter"

91119784.ptd Page 57 550295

550295 V. Description of the invention (52) The endothermic substance is indeed supplied to the molten pig iron bath surface area (exclusively the "fire point") provided by oxygen, and the above-mentioned effect is obtained, and it is preferably supplied to the molten pig iron bath surface through a spray gun. In particular, when the above blowing lance is supplied to the molten pig iron bath surface, and when the refining agent generating and heat absorbing material is supplied to the melting pig iron bath surface, ① the refining agent generating and heat absorbing material is mixed with oxygen (using oxygen as the Carrier gas), the method of supplying to the molten pig iron bath surface from the same air jet port, ② refining agent generation, endothermic material and oxygen are supplied into the spray gun through separate gas supply lines and supplied to the molten pig iron bath by each spray gun Any of the above methods (a carrier gas other than oxygen is used for the supply of the refining agent-generating and heat-absorbing material). From the viewpoint that the refining agent is generated and the endothermic substance is surely supplied to the molten pig iron bath surface area supplied by oxygen, the method of ① is preferable, but the method of ② can also supply the The refining agent generates and absorbs heat and supplies it to a molten pig iron bath surface area where oxygen is supplied through another spray gun. Specifically, for example, a form in which a refining agent using a gas other than oxygen as a carrier gas is supplied from a central air-jet port at the front end of the up-blowing lance to generate heat-absorbing substances, and oxygen is supplied from other air-jet ports around the central air-jet port. good. As the carrier gas, an inert gas such as N2 * Ar is suitable, and a gas endothermic substance (for example, C02) may be used as the carrier gas as described later. In the above method (1), only a part of the air outlets may supply only oxygen, and the other air outlets may separately supply oxygen from the mixed refining agent to generate heat-absorbing substances, and may separately supply the molten pig iron bath surface. The state where the refining agent is generated and the endothermic substance is mixed with oxygen is blown up.

91119784.ptd Page 59 550295 V. Description of the invention (53) The gun is supplied to the surface of the molten pig iron bath, such as the oxygen supply line (top exhaust, piping, and oxygen flow path search in the top blow) A part or all of the refining agent-producing and endothermic substances may be supplied, and tritium may be mixed with oxygen. The refining agent-generating and endothermic substance may be supplied to the molten pig iron bath surface by using a supply means other than the upper blowing blasting (for example, other spray guns). If the spray robbing other than the upper blowing spray gun can supply powder and granules at the specified position in the furnace like the upper blowing spray gun, usually, the side spray blasting used for sampling and temperature measurement is also used in the furnace. No problem with cooling capacity. In addition, overhead input devices such as transmitters and inflow devices can be used if there is no problem in terms of high temperature durability and accuracy of the input position. The oxygen used for the supply of the refining agent and the heat-absorbing substance may be either pure oxygen or oxygen-containing gas. The first to seventh embodiments of the method of the present invention described above can be implemented separately, and the conditions of two or more embodiments can be combined (however, the second state is limited to the use of pot or torpedo models as the trough device. (Refining container case) implementation, but the more the combination conditions, the effect of the method of the present invention is of course even greater. As described above, according to the method of the present invention, it can be carried out efficiently with the minimum amount of # agent added. The “defilling treatment” and further effect know that the properties of the slag formed in the chain are the substances in the solid phase, so it has the great advantage of slag loss when the molten steel is poured out after the life. The phosphorus concentration of the treatment is increased, so when the molten steel is poured after the dephosphorization treatment (especially ^ if the dephosphorization treatment improves the dephosphorization reaction efficiency, then Xuanhaozhong. ,,,, and other, conversion furnace type (Container-like hot liquid outlets, refining containers, etc.)

91119784.ptd Page 60 550295 V. Description of Invention (54) In order to prevent metal and slag from flowing out. That is, in the case where a phosphorus removal treatment with a phosphorus distribution of LP = 200 is performed, and the p content in the molten pig iron after the treatment is 0 · 〇1 5 mass% (specification value: 0 · 〇2 0 mass%), if it flows out, 5 kg / molten pig iron slag around t ο η, then phosphorus is 0 · 〇1 5% by mass is also brought into the decarburization blowing chain conversion furnace, so it must be Lime for phosphorus. However, it does not achieve the original purpose of dissolving pig iron pretreatment. Therefore, it is important to prevent dephosphorization slag from flowing to the next step. In the past, after the dephosphorization treatment of the plastic container using the conversion furnace, the method of minimizing the outflow to the next step is (1) the technology of intercepting the dissolution from the molten steel in the conversion furnace container 7, ( 2) The method of reducing the slag fluidity by controlling the composition of the slag after the treatment, (3) the method of removing the slag (slag removal) from the molten iron ladle after pouring out the molten steel. However, these previous methods are not stable to prevent the loss of slag, and the cost of using consumables is high, the time spent on operation is low, the temperature of the molten pig iron is reduced, and the iron yield is reduced as the slag is removed. To this end, according to the invention & as described above, the solid body is generated in the area of the hot pig iron bath surface and sequentially fixed on the outside of the solid phase body. Therefore, the dephosphorization treatment ends the Japanese slag and turns into a female. The fluidity generated by the decoupling treatment method is' # ^ Small, / check as = the previous effective to prevent the dissolution of molten steel after the dephosphorization treatment is completed, ^ fruit ^ can be out of a conversion furnace container The refining of the hot liquid port can flow out of the molten slag. In addition, as mentioned above, the CaF, which is poured out here, is added in an amount of ikg / dissolved pig iron ton to increase even without adding Cah or increasing it. 、 (Changing dross fluidity

91119784.ptd Page 61 550295 V. Description of the invention (55) Below, according to the present invention, the mechanism for preventing the slag from flowing out / the slag generated will be poured out of the molten steel. Fig. 15 shows the state of the slag / metal compared to the slag produced by the former in the conversion furnace II. Fig. 5 (a) The melting of the molten steel when the molten steel starts to be poured out. In the case of low slag alkalinity or the addition of a large amount of c, the pre-coke method reduces foaming and increases the thickness of the slag. Since 2 causes the slag to be actively melted, the slag is started, and then the dross is allowed to pass through J. If the drossed steel is poured, the furnace is poured out. In contrast, in Figure 15 (b)-it is unavoidable that the molten slag flow melts into the solid phase main body in the case of the method of the present invention, because when the steel is initially poured out: The thickness of the slag is extremely thin, so it is opened at the second! Do not show the metal-like evil near the hot liquid outlet at the end of the dazzling steel material pouring out. In the meltdown of molten steel material / metal vortex occurs' Figure 16 ( a) In the first method, the lightness of the Beam / Begmenia is lighter and the metal is dazzling. In this thirsty stream, the information of the method of the present invention is H. In contrast, as shown in Figure i6 (b) The thirsty stream involved in the metal shown interferes and merges. At this point, the dross will hardly be used. [Example 1] The molten pig iron from the iron in the furnace is blown into the prayer bed and melted as needed. Desiliconization treatment and mechanical stirring in a molten pig iron pot-after sulfur treatment, dephosphorization in a converter furnace container (300 ton) ^ = chemical pig iron component c: 4.5 to 4. 7 mass% Si ·· 0 · (Π ~ 〇 · 28 mass denier G // Mη: 〇 ″ 5 ~ 0. 25 mass%, p: 〇1〇 ~ 〇11 mass%, s: 0, ^ ~,

550295 V. Description of the invention (56) ------- ~ 0.0 0 3% by mass. The refining agent for dephosphorization is the use of lime powder with a particle size of less than imm, and it is blown to the molten pig iron bath surface by spraying with oxygen as the carrier gas. No CaF2 was added to the chain knowing agent. The blowing time is fixed at 10 minutes. Nitrogen is supplied at the bottom of the furnace to dissolve the pig iron at a temperature of 0.05 to 15 Nm3 / min per minute. The original unit of lime and oxygen is 'cross-linked' based on the inclusion of dissolved pig iron, but both lime and oxygen are removed from the desilication part (Dicalcium Silicate ·· Stoichiometric part formed by 2CaO · Si〇2 type The value of) is fixed at 3.51 ^ / melted pig iron chen 11, 9 heart 3 / melted pig iron 11 respectively. The ratio of the supply rate of lime blown by the molten pig iron bath surface (kg / min / molten pig iron ton) to the supply rate of oxygen blown by the molten pig iron bath surface "— ^^^ molten pig iron ton) ratio A / B is 1.7. The amount of lime added is such that the amount of lime Wcao —P (kg / dissolved pig iron ton) and the amount of lime Wcao —Si (kg / dissolved pig iron ton) specified by the above formulas (5) and (6) are Within the total range. In addition, the depression depth L (defined by the value of l as defined in the above formula (7)) generated on the molten pig iron bath surface by blowing the refining agent of oxygen as the carrier gas is controlled to be from 200 to Within the range of 500 mm. In addition, the molten pig iron temperature before and after the descaling treatment is 1 250 to 135 ° C. The amount of slag after the treatment is the amount of lime added and CaO in the slag. The mass balance of the concentration (analysis value of slag) is calculated. The results of each example and the dephosphorization treatment conditions are shown in Table 1. Each average value shown in Table 1 is between 5 kg / melt pig iron ton to 10 kg / melt pig iron ton, 10kg / melt pig iron ton ~ 20kg / melt pig iron ton, more than 20kg / melt pig iron ton ~ 30kg / melt pig iron ton, more than 30kg / melt pig iron ton 40kg / ton pig iron melt, more than 40kg / melting iron ton~50kg / ton pig iron melts in a range of the amount of slag after each treatment, the value of I dephosphorization 6~72ch

91119784.ptd

550295

91119784.ptd Page 64 550295 V. Description of the invention (58) Table 1 Division 1_ Inventive example Inventive example Comparative example Comparative example Average dephosphorization rate (%) 5; oo Dissolved pig iron component (mass%) Minimum after dephosphorization [ P] 0.007 0.009 0.009 0.010 o.oio! | Max [p] 0.010 0.014 0.019 0.023 0.027 | Average [P] 0.008 0.011 0.012 0.014 0.015 Before dephosphorization | Average [p] 0.113 0.111 0.112 0.110 0.111 Mean [Si] 0.04 δ ο 0.12 ο cs 〇 average oxygen content (Nm3AT) cn υη VO ο ii.o! Average lime content (kgAT) ι 1 i CN 5 r- · »ir—1 t—H number of tests (ch) νο τ—Η CS cn τ—Η v〇ON Slag amount after treatment (kg / T) 5 to 10 10 to 20 20 to 30 30 to 40 40 to 50 r--Η CN cn inch un ΙΙΙΙ · ΙΗ 91119784.ptd 65th Page 550295 V. Description of the invention (59) '-[Example 2] The molten pig iron from the furnace is placed in a casting bed and a molten pig iron, if necessary, into a lamp and removed, and mechanically stirred to dissolve The desulfurization treatment f ′ is performed in a pig iron pan, and the dephosphorization treatment is performed in a reformer-type vessel (300,000 n). After removal and treatment of W, the ρ content in the pig iron is 0.1 mass% to 0.1 mass%, and the content is 0.1 mass% or less. The molten pig iron temperature before and after this dephosphorization treatment is 1 25 0 ~ 1 3 5 0 f 'The refining agent for dephosphorization is a calcined lime using Ca〇 main body, sieved to a particle size of 20 or less, and The original unit is based on the Si content of the molten pig iron of 5 to 15 kg / melt pig iron. " This dephosphorization treatment is to scavenge the refining agent through up-blowing and use oxygen as a carrier to transport it to the cold surface to supply the refining agent and oxygen source (chain blowing time: 10 minutes). At this time, the oxygen The ratio A / β of the supply speed of the pig iron ton) to the refining agent supply rate B (kg / min / melted pig iron ton) is operated under various conditions. From the bottom of the furnace, a nozzle is used to blow nitrogen into the molten pig iron at a flow rate of 0.05 to 0.15 Nm3 / min / melted pig iron. No dagger was added to the refining agent, and the slag amount after the treatment was 30 kg / melt pig iron ton or less. The amount of lime added is such that the amount of lime Wca0-p (kg / dissolved pig iron ton) and the amount of lime Wca0-Si (kg / dissolved pig iron ton) specified by the above formulas (5) and (6) are Within the total range. In addition, the depression depth L (the value of L defined by the aforementioned formula) generated on the molten pig iron bath surface by blowing the refining agent of oxygen as the carrier gas is controlled within the range of 200 to 500 mm. The amount of slag after treatment is calculated from the mass balance of the amount of lime added and the CaO concentration (slag analysis value) in molten fish. Oxygen supply rate A (Nm3 / min / melted pig iron ton) and: supply of chain agent

550295 V. Description of the invention (60) The relationship between the ratio A / B of the feed rate B (k g / m i η / molten pig iron t ο η) and the content of P in the molten pig iron after defilling is shown in FIG. 17. According to this figure, if the A / B in the example of the present invention is in the region of 0.3 to 7, the p content in the molten pig iron after the dephosphorization treatment is the target [P] concentration of 0.005 or less, especially 5 mass%. In the case where the Si content in the molten pig iron before the dephosphorization treatment is 0.1 mass% or less, the low-P specification [P] $ 0.0010% by mass can be stabilized. In addition, those with A / b in the 2 · 2.5 ~ 5 area can obtain a particularly low [p], and it is determined in this area that the highest dephosphorization reaction efficiency can be obtained. On the other hand, in areas where A / B is less than 0.3 or more than 7, the P content in the molten pig iron after the dephosphorization treatment is not more than 0.05% by mass of the target [p] concentration. [Example 3] After bathing pig iron from the blast furnace was desiliconized in a casting bed, it was transferred to a molten pig iron pot and treated in this molten pig iron. After slag was discharged, The molten pig iron is moved to a dephosphorization place, and a dephosphorization process is performed. The dephosphorization treatment involves grabbing oxygen as a carrier gas by blowing up and blowing lime powder (refining agent) to the surface of the molten pig iron bath, and blowing lime powder into the pig iron by immersion spraying. In addition, in the comparative example, the above-mentioned blowing and rushing were carried out: ash powder was blown, and the lime powder was blown into the melt by immersion and blasting. In either case, the processing time is 20 minutes. The amount of slag after the treatment was '20 kg / melted pig iron ton or less. Regarding the examples of the present invention, the lime addition force ^ ^ is the amount of lime Wcao —p (kg / melt $ 7 ton) and the amount of lime Wca0-Si (kg / melt) specified in the formulas (5) and (6). Pig iron (ton) is within the total range. In addition, it is blown through the refining agent of oxygen as a carrier gas to

550295 V. Description of the invention (61) The depression depth L (as defined by the above-mentioned formula (7)) of the iron bath surface is controlled to be within the range of 200 ~ 500 mm. In addition, the molten pig iron temperature before and after the dephosphorization treatment is 1 3 0 0 ~ 1 2 2 (TC. The amount of molten slag after the treatment is determined by the amount of lime added and the concentration of C a 0 in the dross (analysis value of dissolved slag). The mass balance was calculated. The results of each example and the dephosphorization treatment conditions are shown in Table 2.

91119784.ptd Page 68 550295 V. Description of the invention Table 2 Differentiating invention examples | Invention examples Invention examples Invention examples Comparative examples | Comparative examples 1 Comparative examples Comparative examples Dephosphorization rate (%) r- CNl oo Melting after dephosphorization Pig iron [P] (mass%) I 0.005 1 0.004 1 1 0.007 1 0.006 0.005 1 0.019 1 0.026 0.022 0.031 Dephosphorization condition oxygen amount (Nm3AT) cn r—Η ο 1—I Bu \ a ν · 0 inch cn CaF2 Add Amount (kgAT) 1 1 1 1 1 1 un ^ ~ \ Addition amount of fine tincture agent (kgAT) η Dip spray gun ο rH τ—Η οο tio inch 'oo cn oo »〇 inch · υη Upper blowing spray gun cn cn cn CO Η oo oo 1 < 1 1 1 1 after dephosphorization by melting pig iron temperature cc) 1 1325 1 1 1330 1 1 1320 1 | 1328 I | 1332 I 1324 ： | 1325 | 1326 1328 Before dephosphorization (° C) 1 1312 1 1 1342 1 1 1338 1 1310 | 1348 | | 1325 | | 1343 | 1330 1329 Φ Ί \ Ί [Ρ] (mass%) 0.112 0.120 1 0.115 1 0.118 0.116 0.116 0.113 0.120 0.110 i dew [Si] (mass%) 0.05 0.04 0.02 0.06 0.07 0.02 0.07 0.03 0.04 τ—Η CN m inch \ 〇oo a \

91119784.ptd Page 69 550295 V. Explanation of the invention (63) [Example 4] The iron slab and iron slab produced by the South Furnace will be treated with iron removal. The iron will be cast on the cast iron and melted pig iron as required. And use mechanical stirring to dissolve in a molten pig iron pot: place: ϊ is a furnace Γ device (300 ton) for repair. The temperature of the molten pig iron after this clean, ALA + Shuangli is 1 25 0 ~ 1 35 0 t, ^ 二 & Erga Song blowing oxygen to the molten pig iron bath surface, and blowing with ① above > ^ ^ = is The carrier gas is to place the lime powder (refining agent) with a particle size of 1 mm or less on the iron surface of 2 Renshi iron. ② Add the lime (refining agent) with a particle size of 1 to 3 mm. From the furnace-type vessel, the bisque & f lice gas was supplied in an amount of 0. 05 ~ O. WNmVmin / melting pig iron ton. ^ While stirring the molten pig iron, it was dephosphorized for 9 minutes. The amount of slag after the treatment is 30 kg / dissolved pig iron ton. With regard to this issue, the amount of lime added is such that the amount of lime ca ^ p (kg / dissolved pig iron ton) and the amount of lime Wca〇-Si ("/ dissolved pig iron two" specified in the above formulae (5) and (6) It is within the total range of 5. X, the refining two people who use * oxygen as the carrier gas = and the depth of the depression generated on the surface of the molten pig iron bath [(L value of the above-mentioned (7) Workers ^ Yiyi) is controlled at Within the range of 200 ~ 500mmi. After treatment = The amount of slag is calculated from the mass balance of the amount of lime added and the concentration of CaO in the slag (analyzed value of the slag). Results of each example and dephosphorization The processing conditions are shown in Table 3.

550295 V. Description of the invention (64) Table 3

φ l5g) m retort distillation AJ -LA OO oo s £ S \ o OO ss VO Dissolved pig iron after dephosphorization [P] (mass%) j 0.009 r—Η r—Η p 0.012 0.008 0.010 0.009 0.015 Η ι— < p 0.015 0.014 0.039 蘅 枳 P Tenglu Township _ _ B C2 / D2 (kg / Nm3) ζρ un cn oo CO 〇oo cn ON | 1 I Ο 〇ο ο ο ο 1 C1 / D1 (kg / Nm3) m oq gor -H oo \ oo un VO ο On 〇csi VO ο cn νο ο 1 1 1 Dephosphorization treatment conditions Q ^ VO 〇υη oo 〇oo 〇oo · νooo C3 or—Η σ \ τ Η 〇 \ · 1 1 1 r \, (Q * t—H r—t IT) 1 < cn cn r __H cn r— < oo CN ^ ~ 1 τ—Η $ r— ί τ—H csl υη ι—Η rH G ^ m 〇〇m cn v〇m 〇On cn 〇 殳 o οο οο Ο τ—Η \ 〇1 1 1 T " " 1 1 ~ \ u * ot-H υη oq oo CX) r Saki On OO oo O oo oq οο οο Ο τ—Η CTn 1 1 1 ffilffifi ^ VO oo cn 〇 \ VO CJ < VO a; Csl a; r Ή cK CN1 ο inch · τ—Η r —H cn VO 2 oo Secret SU addition (kgAT) 1 1 1 1 1 υη 1 cn cn τ—H 蘅 Umbrella 1 p oo un inch · inch · VO un un 〇v〇〇) p § oo i / S 1? Fiber 1 sr—H t—H ssgr—1 T " 'ig CO rH S g cn r—H _ vi 〇τ H f < CD t—H 〇fi 〇r—1 c3 r—Η Ο r—ί 〇 r—ί 〇rH dr—H 〇 璲 wgos 〇s CD sos § r- a \ o S ο Ο S o S ogot—H Csl cn inch \ o οο G \ or—H t H rH Y 锵 TN (M soil I?) The W: country T (gil £) fa5H ^ I »^ Tr: 1 PUM ^ f-s ίβ0ί§0 ^ $ 0 ^ 0 ^ .. ΰ f-G r

91119784.ptd Page 71 550295 V. Description of the invention (65) [Example 5] The molten pig iron from the blast furnace was transferred to a molten pig iron in a casting bed, and then melted in the molten pig iron :: After the slag is discharged, it is placed in the melting furnace in a conversion furnace container (3 00 ton), and the debasing treatment is to use an upper blowing spray to take oxygen as the carrier = blow the powder (refining agent) to the molten pig iron bath surface, And on the shirt, the lime is combined to load the lime in a block. Also compare 1: = The spray gun in the yoke example blows the lime powder, and the above is installed with two people = f does not pass through the upper blow. In the examples, the bottom of the conversion furnace-type container will be nitrogen 0.07 ~ 0.12Nm3 / min / The supply amount of molten pig iron ton is blown in, and dephosphorization treatment is performed for 8 to 14 minutes. In this dephosphorization treatment, the temperature of the molten iron before and after the treatment is 125 to 1305, and the amount of the slag after the treatment is 30 kg / dissolved pig iron ton. The example of the present invention is to make the supply rate B (kg / min / dissolved pig iron ton) of the lime blown from the molten pig iron bath surface and the supply rate A (Nm3 / min / dissolved pig iron ton) blown from the molten pig iron bath surface. ) Ratio A / B is 1 · 7. In addition, the molten pig iron temperature before and after the dephosphorization treatment ranges from 2 5 0 to 3 5 0 C. The melted amount after the treatment is calculated from the mass balance of the amount of lime added and the CaO concentration (slag analysis value) in the slag. The results of each example and the dephosphorization treatment conditions are shown in Tables 4 to 7.

550295 V. Description of the invention Table 4 Differentiating the invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Invention examples Iron slag addition amount * 3 CaO points * 4 (kg / T ) 1 1 1 1 1 1 1 1 1 1 0.80 1.00 Addition (kg / T) 1 1 1 1 1 1 1 1 1 1 1 3.20 4.00 Addition of lime * 2 Overhead (kg / T) 4.88 3.85 2.55 1.64 0.26 〇 \ τ-Η rH 1.68 0.65 0.66 I 0.87 1.08 0.25 1.80 Blow (kg / T) 4.23 (4.38 | 5.18 1 5.14 1 3.93 2.91 3.81 4.15 6.00 4.06! 5.26 2.97 ι 2.93 Calculation of the amount of lime 値 * 1 Total 8.76 ^ 11.53 7.88 to 10.57 丨 7.37 to 9.95 6.42 to 9.65 3.83-6.87 3.75 to 6.29 5.13 to 7.46 4.45 to 7.29 6.31 to 9.02 4.57 to 7.15 5.99 to 8.78 4.02 to 6.84 5.53 to 7.86 WcaoP (kg / T) 2.76 ～ 5.53 | 2 · 68 ～ 5 · 37 | 2.57 ～ 5 · 15 3.22-6.45 3.03-6.07 2.55-5.09 2.33-4.66 2.85 ～ 5.69 2.71 ～ 5_42 2.57-5.15 2.79 ～ 5.58 丨 2.82 ～ 5.64j 2 · 33 ～ 4.66 WcaoSi (kg / T) ο vd (Ν in oo inch · (Ν m * 〇〇〇 (Ν rH 〇〇 < Ν · 〇 〇 (Ν rn (N τ-Η (Ν m dissolved pig iron Points (% by mass) g after dephosphorization 0.013 0.016 1 0.016 | 0.013 0.016 0.017 0.011 0.011 0.013 0.018 1 _1 0.009 0.014 j 0.008 nn g 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.013 0.13 0.112 1 before dephosphorization 0.108 0.132 0.125 0.107 0.099 0.118 0.113 0.108 0.116 0.117 j 0.099 g I 0.15 0.13 1 0.12 0.08 0.02 0.03 0.07 0.04 0.09 0.05 0.08! 0.03 ι 0.08 6 ψ " < CN m inch to 卜 〇〇〇 〇r-Η rH τ-Η (N Η m Y knows ΓΓYt (_TW (s following I?)) 3¾: _τ is—OSAV + dlosAV: 4Ι4Π ϋ} · ώ ^ 1 ^ δ: islosM Msfc ^ s): ΡΗ—§Μ Γ 11_ _ Li 1 9lll9784.ptd Page 73

No. Depression depth of molten pig iron bath surface (mm) Dephosphorization rate (%) Lime efficiency 量 Blow lime amount / Wcao-P * 1 Division 1 300 88.7 0.887 1.53 Invention Example 2 325 85.7 0.857 1.63 Invention Example 3 256 85.2 0.852 2.01 Invention Example 4 268 90.2 0.902 1.59 Invention Example 5 289 87.2 0.872 1.29 Invention Example 6 295 84.1 0.841 1.14 Invention Example 7 312 88.9 0.889 1.63 Invention Example 8 415 90.7 0.907 1.46 t Invention Example 9 210 88.5 0.885 2.21 ^ Invention Example 10 450 83.3 0.833 1.58 Inventive Example 11 480 92.2 0.922 1.88 Inventive Example 12 290 88.0 0.990 1.05 Inventive Example 13 360 91.9 0.973 1.26 Inventive Example M Wcao_P is the amount of lime calculated with 7? Cao = 1 550295 5. Description of the invention (67) Table 5

Hill 91119784.ptd Page 74 550295 V. Description of the invention (68) Table 6 Dissolved pig iron composition (mass%) Calculation of lime amount 値 (kg / T) * 1 Lime addition amount * 2 No. Before depuration target dephosphorization Upper blow section [Si] [P] [P] [P] (kg / T) (kg / T) 14 0.10 0.122 0.013 0.015 13.97 — 13.97 Comparative Example 15 0.07 0.108 0.013 0.011 12.18 — 12.18 Comparative Example 16 0.02 0.113 0.013 0.009 12.82 — 12.82 Comparative Example * 1 Slag alkalinity: 3, Lp: 240 Necessary amount of lime calculated * 2 Blowing: Blow the lime powder (fine tincture) on the surface of the molten pig iron bath with an upper blowing spray gun: Place the lime (Refining agent) Load η__ι 91119784.ptd for the upper position Page 75 550295

V. Description of the invention (69) Table 7 No. Dephosphorization rate of molten pig iron bath surface (mm) Depression depth (° / 〇) 14 450 87. 7 15 450 89. 8 16 330 92.0 Example 6] Ash efficiency (1) 0. 330 0. 299 0. 320

After the molten pig iron from the blast furnace is desiliconized in a casting bed, it is moved to a molten pig iron pot and the stone is treated in this molten pig iron pot. After the slag is discharged, the molten pig iron is charged and converted. The furnace-type container (300t0n) was performed and the stone was processed. This defilling process is to blow oxygen to the surface of the molten iron bath through the blow-up spray, and use ① the above oxygen as the carrier gas to blow the lime powder (refining agent) below the grain to the surface of the molten iron bath, ② Add the refining agent by any method of placing ^ 石 ^ (refining agent) on top. The gas was blown in from the bottom of the chemical furnace type trough at a site of 0.1 N m3 / mi η / molten pig iron t 〇η and the molten pig iron was stirred for 10 to η minutes. Lin processing. In addition, the molten pig iron temperature and the amount of scrap iron added before the dephosphorization treatment were adjusted to control the molten pig iron temperature at the end of the dephosphorization treatment. After the second treatment, the value of Charlie was 30 k g / molten pig iron t ο η or less. Regarding the examples of the present invention, the amount of lime added is such that the amount of lime Wca0-P (kg / dissolved pig iron ton) and the amount of lime Wcao—Si (kg / dissolved pig iron hemp) specified by the above formulas (5) and (6) Within the total range. In addition, the depression depth L (the value of L as defined by the above formula (7)) generated by blowing the refining agent of oxygen as a carrier gas on the surface of the molten pig iron is controlled within the range of 20 to 50 mm. . The melted amount after processing

550295 V. Description of the invention (70) Calculated by adding the mass balance between the amount of lime and the Ca0 concentration in the slag (analyzed value of the slag). The results of each example and the dephosphorization treatment conditions are shown in Table 8. Table 8

No. Dissolve before dephosphorization, dissolve pig iron, ferrite temperature, dephosphorization conditions, dephosphorization rate (%), distinguish [Si] (MM%) [P] (mass%) before dephosphorization, Γ〇 after dephosphorization (° C) Addition amount (kg / V Cafi addition amount (kg / T) Refining agent addition method * 1 Oxygen amount (NmVT) Dissolved pig iron after dephosphorization [P] (mass%) 1 0.05 0.106 1320 1375 6.5 One blow 10.2 0.012 89 Invention Example 2 0.04 0.110 1315 1400 6.1 — blowing 9.5 0.014 87 invention example 3 0.08 0.102 1285 1446 7.7 — blowing 10.3 0.015 85 invention example 4 0.02 0.115 1267 1440 5.3 — blowing 9.6 0.014 88 invention example 5 0.09 0.106 1354 1421 8.1 — blowing 10.2 0.012 89 h Invention Example 6 0.06 0.108 1302 1367 6.9 One Blow 10.1 0.008 93 Invention Example 7 0.07 0.110 1314 1385 7.3 0.2 Blow 9.7 0.011 90 Invention Example 8 0.03 0.107 1298 1375 5.7 0.7 Blow 10.2 0.014 87 Invention Example 9 0.06 0.108 1315 1410 6.9 1.6 Top 10.4 0.032 70 Comparative Example 10 0.15 0.106 1320 1403 10.5 First Top 10.2 0.034 68 Comparative Example 11 0.05 0.106 1343 1465 6.5 Top Top 0.039 0.0 Comparative Example 12 0.06 0.112 1298 13 21 6.9 — BU 9.9 0.033 71 Comparative Example 1 Blowing. The above spray blast blows the lime powder (refining agent) to the > place on the surface of the pig iron bath, and puts the lime (refining agent) on top. [Example 7] After the desmelted pig iron from the blast furnace is desiliconized in a casting bed, it is moved to a molten pig iron pan and subjected to desilication treatment in the molten pig iron pan. After the slag is discharged, the molten pig iron is charged into the molten pig iron. Conversion furnace type container (300 ton) for dephosphorization treatment, dephosphorization treatment. This dephosphorization treatment

T Page 77 550295 V. Description of the invention (71)-Oxygen = lime powder (refining agent) and endothermic negative σ of carrier gas with a particle diameter of 1 mm or less are sent to the molten pig iron bath surface. The endothermic substance is CaC03 or Ca (0H & (both with a particle size of 1 mn) or less), and it is mixed with lime powder in a specified ratio in advance. Nitrogen is dissolved in the furnace bottom of the conversion furnace type at a temperature of 0 · INm3 / mi η / The supply of pig iron ton is blown in, and the molten pig iron is stirred while being subjected to a de-disc treatment process from 10 to 11. The adjustment is also made to the temperature of molten pig iron and the amount of scrap iron added before the de-filling treatment to control the end of the dephosphorization treatment. Temperature of molten pig iron. The amount of dross after treatment is 30 kg / melt pig iron t ο η or less. Regarding the examples of the present invention, the amount of lime added is such that the lime specified by the above formula (5) and (6) ^ Wcao — P (kg / melted pig iron t〇n) and the amount of lime wca〇-Si (kg / melted pig iron ton) are within the total range. In addition, it is generated by blowing the refining agent of oxygen as a carrier gas on the molten pig iron bath surface. The depression depth 1 (the L · value defined by the above formula (7)) is controlled within the range of 2000 ~ 500 mm. The amount of dross after treatment is the analysis value of added lime and slag Calculate the balance of Ca0 concentration. Results of each example and dephosphorization treatment conditions Table 9.

— 第 78 ----— 550295 V. Description of the invention (72) Table 9 Differentiate the invention examples Invention examples Invention examples Invention examples Invention examples Dephosphorization rate (%) cn ON 5; Dissolved pig iron after dephosphorization [P] (Mass%) 0.009 0.010 0.011 0.012 0.008 0.009 Addition amount of endothermic substance (kgAT) r ~ i cn cn CN MD 1—Η 〇4 inch cn cn CN Type 1 CaC〇3 1 1 CaCOs CaC〇3 1 Ca (〇H) 2 1 CaC〇3 1 Ca (〇H) 2 Oxygen amount (NmYT) 1 10.6 1 | 10.80 | 〇 \ 〇 Csl Ο τ—H Refining agent addition method * 1 Blowing 丨 Blowing i Blowing Blowing Blowing CaF2 Adding amount (kgAT ) 1 1 1 1 cn oq Refining agent added amount (kg / T) r- v〇τ— < ON RC after molten iron temperature dephosphorization) 1 1423 1 1 1426 1 丨 1447, Li412j 1 1385 1 cn τ--H Before dephosphorization (° C) 1 1319 1 1 1347 1 1 1299 1 1 1275 1 1 1297 1 I 1311 1 Φ chain M Μ [P] (mass%) 0.108 0.111 0.105 1 0.106 1 0.111 0.104 S [Si] (mass %) 0.03 so 0.08 0.03 0.04 0.06 η 1 < CN) cn inch 晅 钃 锲 Μ hair 8 my m listen Μ township_11 91119784.ptd page 79 550295

The molten pig iron from the blast furnace was desiliconized in a molten pig iron pot [Example 8], after the slag was discharged, the molten pig iron was charged into a converter-type vessel (300 tons), and dephosphorized. . In this dephosphorization process, a stirring gas (nitrogen gas) of about 0.1 Nm3 / mln / melted pig iron ton is blown from the furnace bottom of the conversion furnace type vessel, and the molten pig iron is stirred while using the upper blowing spray to blast oxygen, Lime powder (CaO-based refining agent) and a gas endothermic substance are supplied to the molten pig iron bath surface. In addition, Cal was not added to the refining agent. The amount of slag after the treatment is 30 kg / melt pig iron or less. Supply speed B (kg / min / melt pig iron) of the lime blown on the molten pig iron bath surface, supply of oxygen blown by the melt pig iron bath surface, 'a speed A (Nm3 / min / melted pig iron t ON) The ratio A / B is 17. The amount of lime added is such that the amount of lime Wcaop (kg / dissolved = pig iron ton) and the amount of lime Wcao —Si (kg / dissolved pig iron ton) specified by the above formulas (5) and (6) are the total fe Within. In addition, it is blown through the refining agent of oxygen as a carrier gas.

The depression depth L (the value of L as defined by the aforementioned formula (7)) generated from the molten pig iron bath surface is controlled within a range of 200 to 500 mm. In addition, the molten pig iron temperature before and after the dephosphorization treatment is 1250 to 135 (TC. The amount of slag after the treatment is calculated from the amount of lime added and the quality of the Ca0 concentration (slag analysis value) in the slag. 、 He Shang blowing oxygen spraying is using the spraying with 1 center hole and 3 surrounding holes as + air vents. ㊄ ㊄ The lime powder is used with a particle size of 3 in m or less, and it is made by oxygen from a cutting device. It is cut out for carrier gas, transported in the pipe and supplied to the upper mouthpiece, and the central hole and oxygen are supplied to the molten pig iron bath surface. On the other hand, the island

9ll ^ 784.ptd Page 80 550295 V. Description of the invention (74) In addition, the pipeline is supplied with oxygen to the upper blowing and spraying and is supplied to the molten pig iron bath surface from the surrounding holes. The total oxygen supply was 1.5 N m3 / m i η / molten pig iron t ο η. Add a specified endothermic substance to the oxygen lines of the two above. This gas endothermic substance uses carbon dioxide and water vapor, and the mixing ratio with respect to oxygen is 10 to 40% by volume (relative to 100 other than oxygen). Further, in a comparative example, oxygen was supplied to the molten pig iron bath surface by a top-blowing spray, and a block of lime (CaO-based refining agent) was placed on top. The results of each example and the dephosphorization treatment conditions are shown in Table 10. Table 10

No. Dissolved pig iron components (% by mass) Dephosphorization conditions distinguish between dephosphorization [Si] [P] Endothermic substance lime (kg / T) Dephosphorization time (minutes) Species addition amount before dephosphorization (%) * 1 1 0.09 0.110 0.011 C〇2 5 5.6 6.4 Invention Example 2 0.08 0.108 0.010 C〇2 10 5.2 6.1 Invention Example 3 0.07 0.109 0.008 C〇2 25 4.6 5.2 Invention Example 4 0.07 0.109 0.007 C〇2 40 4.3 5.0 Invention Example 5 0.13 0.109 0.010 C0 2 25 5.8 6.6 Invention Example 6 0.07 0.107 0.010 h2o 10 5.1 5.9 Invention Example 7 0.07 0.110 0.008 h2o 25 4.8 5.5 Invention Example 8 0.07 0.105 0.015 — — 8.0 11.0 Comparative Example 9 0.08 0.108 0.014 — — 8.5 11.5 Comparative Example * 1: 100% (volume%) with respect to 100% of oxygen [Example 9] The blast furnace molten pig iron was desiliconized in a molten iron ladle, and then slag was discharged, followed by dephosphorizing treatment in the molten iron ladle. This dephosphorization process is

91119784.ptd Page 81 550295 V. Description of the invention (75) The molten pig iron is blown with nitrogen gas of 3Nm3 per minute, the molten pig iron is stirred, and oxygen and lime powder (CaO-based refining) Agents) and endothermic substances are supplied in any of the following forms ① to ④. In addition, CaF2 was not added to the fine chain agent. The amount of slag after treatment is 30 kg / ton of molten pig iron. The ratio A / B of the supply speed B (kg / min / dissolved pig iron) of the lime blown from the molten pig iron bath surface to the supply speed A (Nm3 / min / dissolved pig iron ton) of the oxygen blown from the molten pig iron bath surface is 1.7. The amount of lime added is within the range of the total amount of lime Wca0-P (kg / dissolved pig iron 7 ton) and the amount of lime Wcao — Si (kg / dissolved pig iron ton) specified by the above formulas (5) and (6). . In addition, the depression depth L (defined by the formula (7) above) is controlled to be within a range of 20 to 500 mm by blowing the refining agent of oxygen as a carrier gas on the surface of the molten iron bath. In addition, the temperature of the dephosphorization pig iron is 1 250 0 to 1 3 50 t. The amount of lime in the molten slag and the concentration of CaO in the dissolved slag after the treatment (the slag analysis value is 0. Open lime powder, C02 . Lime powder, CaC03 (stone lime powder, C02, CaC03 (limestone), or ① Example of the present invention: the above blow and spray to supply oxygen ② Example of the present invention: The above blow and spray to supply oxygen limestone) or Ca (0H) 2 (Slaked lime) ③ Example of the present invention: The above blowing and blasting supply of oxygen CaC03 (limestone). ④ Example of the present invention: The above blowing and blasting supply of oxygen Ca (0H) 2 (slaked lime). Stone and powder, stone. Substance, will It is made by cutting out

550295 V. Description of the invention (76) ----- It is transported inside, and merges with the oxygen supplied through other distribution g at the entrance of the upper blowing nozzle, and the 3 air outlets and gas from the front of the upper blowing gun. The jets are jointly supplied to the bath surface. The total oxygen supply is 6 0 0 N m3 per hour. The mixing ratio of C 2 with respect to oxygen is 25% by volume (except for oxygen with a number other than 1000). In addition, lime powder, CaC03 (limestone), and 〇8 (01〇2 are added at a rate of 70 to 80 kg per minute in an amount equivalent to 0.30. Further, in a comparative example, oxygen is supplied to the molten pig iron bath surface through a top-blowing spray And the lime powder was injected into the molten pig iron through the immersion spray gun. The results of each example and the dephosphorization treatment conditions are shown in Table 11.

Table 1 1

No. Dissolved pig iron components (% by mass) Dephosphorization conditions distinguish between dephosphorization [Si] [P] endothermic substance lime usage (kg / T) dephosphorization time (minutes) gaseous species addition amount before dephosphorization ( kg / T) 1 0.08 0.115 0.008 C〇2 — — 5.0 9.8 Invention Example 2 0.07 0.Π4 0.008 C〇2 CaCOs 1.1 4.4 9.7 Invention Example 3 0.12 0.116 0.011 C〇2 CaC03 1.2 5.9 13.0 Invention Example 4 0.08 0.115 0.009 — -CaC〇3 3.6 3.3 13.2 Invention Example 5 0.08 0.114 0.010-CaC〇3 8.5 — 14.2 Invention Example 6 0.07 0.113 0.011-Ca (OH) 2 3.5 2.2 11.5 Invention Example 7 0.07 0.113 0.010-Ca (OH) 2 6.0-11.6 Invention Example 8 0.06 0.114 0.017 One-One 7.9 16.5 Comparative Example 9 0.15 0.114 0.021 — ^-— One 10.5 20.1 Comparative Example

Industrial applications

9]]] 9784.ptd Page 83 550295

91119784.ptd Page 84 550295 Brief description of the drawing Figure 1 is a graph showing the relationship between the amount of slag after dephosphorization and the content of p in molten pig iron. Fig. 2 is a graph showing the relationship between the Si content in molten pig iron before dephosphorization and the amount of dross after dephosphorization. Fig. 3 is an explanatory view showing an embodiment of a method of the present invention using a converter-type vessel. Fig. 4 is a graph showing the relationship between the ratio of the amount of refining agent added to the total amount of refining agent and the amount of necessary ash in the second embodiment of the method of the present invention. FIG. 5 shows the second embodiment of the method of the present invention, blowing the entire amount of the refining agent through the upper blowing spray to the molten pig iron bath surface and blowing into the molten pig iron through the immersion spray gun and / or blowing nozzle In this case, the relationship between the ratio of the refining agent addition amount to the total refining agent addition amount and the dephosphorization rate through the upward blowing spray gun. Fig. 6 is an explanatory diagram showing an example of the implementation status of the second embodiment of the method of the present invention. FIG. 7 is a diagram showing the third embodiment of the method of the present invention and the previous method, the P content in the dissolved pig iron after dephosphorization becomes 0. 0 1 2% by mass, the original unit of C a 0 and defilling Diagram of efficiency. FIG. 8 is a graph showing the relationship between the Si content in the molten pig iron and the necessary amount of lime in the fourth embodiment of the method of the present invention and the conventional method. Fig. 9 is a graph showing the relationship between the amount of lime necessary for dephosphorization and the lime efficiency cao and the content of P in dissolved pig iron after dephosphorization in the fourth embodiment of the method of the present invention and the previous method.

91119784.ptd Page 85 550295

Brief description of the drawings-Fig. 10 is a diagram showing the amount of lime χ blown from the molten pig iron bath surface and the amount of lime used for descaling ^ by the upper blowing spray in the fourth embodiment of the method of the present invention. Relationship between ratio x / Wcao_P and ρ content in molten pig iron after dephosphorization. 11 (a) and 11 (b) show the depth L and dephosphorization of the depression on the molten pig iron bath surface by blowing oxygen or blowing the refining agent with oxygen as the carrier gas in the fifth embodiment of the method of the present invention. Relationship between efficiency and P content in molten pig iron after treatment. Removal * Fig. 12 shows the si content in molten pig iron, the temperature of molten pig iron after dephosphorization, and the efficiency of deliming lime in the sixth embodiment of the method of the present invention in the dephosphorization treatment without adding CaI? 2. Relationship diagram. FIG. 13 shows that in the sixth embodiment of the method of the present invention, C a F2 is added in the descaling treatment after the dephosphorization pig iron temperature> 1 3 60 0 to 1 4 5 0 ° C The relationship between the amount and the efficiency of dephosphorized lime. Figures 14 (a) to (e) are explanatory diagrams showing an example of a supply form in which oxygen, a refining agent, and an endothermic substance are applied to a molten pig iron bath surface using a top-blowing spray in the seventh embodiment of the method of the present invention. Figures 15 (a) and (b) are model illustrations showing the state of the slag / metal at the beginning of tapping in the uranium method using the plastic container of the converter and the method of the present invention. Figure 0 Figure 16 ( a) and (b) are model diagrams showing the state of the molten slag / metal near the exit of the molten steel at the final stage in the previous method and the method of the present invention using a reforming furnace pear container. FIG. 17 is a diagram showing an example of the first embodiment of the method of the present invention, the oxygen

91] 19784.ptd p. 86 550295

91119784.ptd Page 87

Claims (1)

550295 VI. Scope of patent application 1. A method for manufacturing low-phosphorus dissolved pig iron, which is characterized by adding a refining agent of an oxygen source and a CaO source to a container holding the molten pig iron, and performing dephosphorization treatment of the molten pig iron pretreatment to produce low phosphorus In the method of dissolving pig iron, oxygen and at least a part of the refining agent are blown to the surface of the molten pig iron bath for dephosphorization treatment through an upper blowing spray, and the slag amount after the treatment is 30 kg / lacquered pig iron ton or less. 2. The manufacturing method of the low-phosphorus molten pig iron according to item 1 of the scope of the patent application, wherein at least a part of the refining agent supplied by the upper blowing spraying is blown to the molten pig iron bath surface area blown by oxygen. 3. The manufacturing method of the low-phosphorus molten pig iron according to item 2 of the scope of the patent application, wherein at least a part of the refining agent supplied by the upper blowing lance is blown to the fire generated on the molten pig iron bath surface by oxygen blowing. point. 4. For example, the manufacturing method of low-phosphorus molten pig iron in item 2 of the scope of the patent application, wherein at least a part of the refining agent is blown to the surface of the molten pig iron with oxygen as a carrier gas. 5. The manufacturing method of the low-phosphorus molten pig iron according to item 1 of the scope of patent application, which is a process of dephosphorizing the molten pig iron having an Si content of 0.15% by mass or less. 6. The manufacturing method of low-phosphorus molten pig iron according to item 1 of the scope of patent application, which is to dephosphorize the molten pig iron having a Si content of 0.007 mass%. 7. The method for manufacturing a low-phosphorus molten pig iron according to item 1 of the scope of patent application, which is a dephosphorization treatment for a molten pig iron having an Si content of 0.3% by mass. 8. For the manufacturing method of low-phosphorus molten pig iron according to item 1 of the scope of the patent application, the amount of slag after the treatment is 20 kg / melted pig iron ton or less. 91119784.ptd Page 88 550295 6. Scope of patent application • For example, the manufacturing method of low-phosphorus molten pig iron in item 1 of the scope of patent application 7 It is the smelting after treatment > The check amount is 10 kg / melted pig 丨 0 n the following. 10 · If the method for manufacturing low-phosphorus molten pig iron according to item 1 of the scope of the patent application is to convert the refining agent blown by the molten pig iron bath surface into (: 8 () supply rate B (kg / min / melted pig iron ton) ), The supply rate of oxygen blown from the molten pig iron bath surface A (Nm3 / min / molten pig iron ton) is to satisfy the following (丨) formula 0.3 SA / B S7… ⑴ 工 1 1 · If the scope of patent application The method for manufacturing low-phosphorus molten pig iron according to item 丨 is to convert the refining agent blown from the molten pig iron bath surface into Ca0 supply rate B (kg / min / melted pig iron ton) and blow the molten pig iron bath surface. The supply rate of milk gas MNmVmin / dissolved pig iron t 0 n) is to satisfy the following formula (2) SA · B S2 · (2) 12. If the low phosphorus dissolved pig iron of item 丨 of the application scope is °, it is Use a pot-type or torpedo container as the six "quoti" device, grab the oxygen and at least a part of the 2: by the top blow spray, and grab the surface of the cast iron bath, and pour and dip into the Θ The gas from which P reaches the solution is blown into the molten pig iron. Adults' mouths will contain powder. 13. As in the manufacturing method of low-rock dance molten pig iron No. 12 of the scope of the patent application, the powder is part of the refining agent through the impregnation spray gun and / or the blowing nozzle. No. 14. The low-phosphorus dissolution method according to item 12 of the scope of application for patent, wherein it is blown to the manufacturer of the molten pig iron by a blow-up spray gun at a level below 0.5 w / mina of the pig iron ton. ^ The amount of oxygen on the face is 91119784.ptd Page 89 550295 VI. Scope of patent application, 15 · If the manufacturer of low melting molten pig iron in item 12 of the patent application scope, it is 80% by mass of the refining dose added to the descaling treatment. The above is blown to the surface of the molten pig iron bath through the blow-up spray gun. ， 16 · If the method of manufacturing low-phosphorus molten pig iron according to item 12 of the scope of the application for patent, it is the method of making substantially the entire amount of the refining agent through an upper blowing spray ☆ blowing to the surface of the molten pig iron bath and through the dipping blasting The molten pig iron is added by blowing with a gun and / or a blowing nozzle, and the amount of the refining agent added through the upper blowing spray is 20 to 80% by mass of the total amount of refined added. The manufacturing method of low-dissolved molten pig iron as described in item 1 of the scope of the patent application is to make the supply rate of the refining agent and the oxygen supply rate blown to the molten pig iron bath surface to satisfy the following formulas (3) and (4) The condition of the formula is to perform dephosphorization treatment: (Cl / Dl) XC2 / D2). &Quot; (3) Cl > C2… ⑷ where 'C1 · average of the supply rate of the refining agent converted to ca 〇 Value (kg / min / melt pig iron ton) C 2 · The average value of the refining agent supply rate converted to ca 〇 in the later stage of defilling process (kg / min / melt pig iron ton) D1: the oxygen supply rate in the early stage of defilling process Average value (Nm3 / min / dissolved pig iron ton) D2 ·· The average value of the oxygen supply rate in the later stage of dephosphorization treatment (Nm3 / min / dissolved pig iron ton). 1 8 · If the method for manufacturing low-phosphorus molten pig iron No. 17 in the scope of patent application 'is to supply the refining agent converted into C a 0 during the descaling process 91119784.ptd Page 90 550295 6. Scope of patent application —— ----. Speed and oxygen supply speed are continuous and / or phased changes. 19 · If the manufacturer of low-phosphorus molten pig iron in item 1 of the scope of patent application is for molten pig iron with Si content of 0.15% by mass or less, oxygen and at least a part of the refining agent are blown to melt by spraying The pig iron bath surface is subjected to dephosphorization treatment, and in this dephosphorization treatment, the amount of sublimed lime Wcao-P (kg / dissolved pig iron ton) obtained by the following formula (5) and The calculated ash content Wcao —Si (kg / dissolved pig iron ton) is added to the total amount of lime refining agent: (5) Wcao —P = (dissolved pig iron [p]-target [ρ]) χ (1〇 / 62 ) χ 56χ 3 / r \ cao · · where dissolved pig iron [P]: p in dissolved pig iron before dephosphorization treatment > degree (mass%) target [P]: target molten pig iron after dephosphorization treatment P concentration (mass%) 7; cao (lime efficiency) = 0.5 to 1 Wcao —Si = molten pig iron [Si] X (1 0/28) X 5 6 X 2 · _ · (6) where 'melt Pig iron [S i]: Concentration (% by mass) of molten pig iron before desquamation. 2 0 · The manufacturing method of low-phosphorus dissolved pig iron according to item 9 of the scope of the patent application, which is 80 mass% or more of the amount of lime Wcao —P (Wcao —P calculated by π cao = l) The lime is blown to the surface of the molten pig iron bath by blowing up. 2 1 · If the method for manufacturing low-phosphorus molten pig iron according to item 丨 9 of the patent application scope ’is the use of lime powder, burnt lime, block limestone, containing unreacted 91119784.ptd Page 91 550295 One or more of them are used as a refining agent for iron slag equivalent to the amount of lime Wca0_Si CaO. The application of the low-phosphorus molten pig iron in the first target area of Shenyue's patent is based on the wide production defined by the following formula (7). The carrier gas is blown into the refining agent and the depression depth L generated on the cold surface of the molten iron supply, Hachiman / Γ, / combined pig iron is controlled to 200 ~ 500mm: L = L0 X exp {(-0 · 78x Lh) / L. }… ⑺ L0 = 63x {(F〇2 / n) / dt} 2/3 where, lh: the height of the blow-up spray grab (mm) F〇2 · the oxygen supply speed from the blow-up spray grab (Nm3 / hr) n: Nozzle hole number of upper blow nozzle dt: Nozzle hole diameter (mm) of upper blow nozzle (However, when the nozzle diameter of plural nozzle holes is different, it is the average hole diameter of all nozzle holes ). 2 3. If the method for manufacturing low-phosphorus dissolved pig iron according to item 丨 of the patent application scope, the dephosphorization treatment is performed under the condition that the addition amount of Cah is 2kg / melted pig iron or less or that CaF2 is not substantially added. 2 4 · If the method for manufacturing low-phosphorus molten pig iron according to item 1 of the scope of patent application is for molten pig iron with Si content of 0.15 mass% or less, the addition amount is 1 kg / melt pig iron ton or less. Under the condition that CaF2 is not added, the oxygen and at least a part of the refining agent are blown to the surface of the molten pig iron bath through a blow-up spray, and the molten pig iron temperature at the end of the dephosphorization treatment is 1 3 6 0 ° C. ~ 1 4 5 0 ° C. 25. For the manufacturing method of low-phosphorus molten pig iron according to item 丨 of the patent application scope, 550295 6. Scope of patent application It is a substance that supplies heat to the molten pig iron by chemical reaction and / or thermal decomposition reaction to the molten pig iron bath surface area supplied with oxygen. 2 6. The method for manufacturing low-phosphorus molten pig iron according to item 25 of the scope of patent application, which is to supply at least a part of a substance that absorbs the heat of molten pig iron through a chemical reaction and / or a thermal decomposition reaction, and supply it to oxygen blowing The melting point of the molten iron bath surface. 2 7. The method for manufacturing low-phosphorus molten pig iron according to item 25 of the scope of patent application, wherein the substance that absorbs the heat of molten pig iron through chemical reaction and / or thermal decomposition reaction is carbon dioxide, water vapor, nitrogen oxide, One or more of metal carbonate and metal hydroxide are selected. 2 8. The method for manufacturing low-phosphorus molten pig iron according to item 27 of the scope of the patent application, wherein the substance that absorbs the heat of the molten pig iron through a chemical reaction and / or a thermal decomposition reaction is a metal of C02 or 1120 that undergoes thermal decomposition One or more kinds of carbonates and hydroxides of metals in which 02 or 1120 undergoes thermal decomposition are selected. 2 9. The method for manufacturing low-phosphorus molten pig iron according to item 28 of the scope of patent application, wherein the substance that absorbs the heat of molten pig iron through chemical reaction and / or thermal decomposition reaction is CaC03, Ca (0H) 2, CaMg ( C03) 2 or more are selected. 30. The manufacturing method of low-phosphorus molten pig iron according to item 1 of the scope of patent application, which is to supply one of CaC03, Ca (0H) 2, and CaMg (C03) 2 to the molten pig iron bath surface area where oxygen is supplied. Substances that generate substances for the refining agent and that absorb the heat of molten pig iron through a chemical reaction and / or a thermal decomposition reaction to replace part or all of the refining agent of the CaO source. 91119784.ptd Page 93 550295 VI. Application scope of patent 31. For the manufacturing method of low-phosphorus molten pig iron No. 30 of the scope of patent application, it is selected from CaC03, Ca (0H) 2, CaMg (C03) 2 At least one part of at least one part is supplied to the fire point generated by melting the pig iron bath surface by blowing oxygen. 3 2. The manufacturing method of low-phosphorus molten pig iron according to item 1 of the scope of patent application, which is to dephosphorize and refine the P content of 0.1 to 10 mass% or more to the required P content of crude steel (steel composition Specifications). 3 3. The method for manufacturing a low-phosphorus molten pig iron according to item 32 of the scope of the patent application, wherein the content of P in the molten pig iron after dephosphorization treatment is not more than 0.10% by mass. mm mm II Μ 91119784.ptd Page 94