JP5365678B2 - Powder blowing lance with burner function, molten iron refining method and molten metal smelting reduction method using the powder blowing lance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder injection lance capable of reducing a compound ratio of molten iron, and a method for refining molten iron using the injection lance. <P>SOLUTION: The powder injection lance is provided with: a refining oxygen gas injection nozzle 5b1 which has multiple ejection openings that are arranged at intervals along a circular trajectory and inject an oxygen gas into an iron bath housed in an iron bath type refining furnace; and a burner nozzle 5b2 which has an axial center coaxial with the central axis of the circular trajectory, and which has an ejection opening which forms a flame on the inside of the refining oxygen gas injection nozzle and which injects into the iron bath a powder to which heat has been transferred by the flame. By regulating an indicator F showing the positional relation between the ejection opening of the refining oxygen gas injection nozzle 5b1 and the ejection opening of the burner nozzle 5b2, the interference of the flame by the refining oxygen gas and the burner becomes small, a flame temperature is kept high, and the powder is efficiently heated. By this means, the efficiency of heat transfer to the iron bath is improved. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a powder blowing lance imparted with a burner function, a molten iron refining method and a smelting reduction method using the powder blowing lance.

In recent years, in the manufacturing process of molten steel, from the viewpoint of environmental protection, an operation has been adopted in which the amount of scrap used is increased and the hot metal mixing ratio is lowered in order to reduce the amount of CO ₂ emission.

  In order to lower the hot metal mixture ratio, in order to melt a large amount of scrap, a thermal margin is required.

  As a countermeasure for this, for example, Patent Literature 1 discloses a method of adding a carbon source (heat source) for heating to the hot metal during the dephosphorization process of the hot metal to compensate for the shortage of the heat source.

  In Patent Document 2, carbon monoxide (CO) generated in a converter and oxygen blown by a lance are burned on a bath surface of a molten metal (so-called secondary combustion), and the combustion heat is converted into molten iron. A method of applying heat is disclosed.

  On the other hand, in the dephosphorization treatment of hot metal, the elution of fluorine from the slag generated at that time is a problem, and the dephosphorization treatment should be performed efficiently without using a fluorination source such as fluorite. Is desired.

As a means for that purpose, Patent Document 3 describes that in a top bottom blowing converter, mixed powder of CaO and Al ₂ O ₃ is sprayed from the top blowing lance to the hot metal, and stirring gas is blown from the furnace bottom to stir the hot metal. A method of performing a dephosphorization process is disclosed.

  Further, in Patent Documents 4 to 6, for the purpose of improving the efficiency of the metallurgical reaction, in order to promote hatching of slag, a burner function is given to the upper blowing lance, and a dephosphorizing agent is ejected from the central hole of the burner. And heating and adding methods are disclosed.

JP-A-9-20913 JP 60-67610 A JP 2000-345226 A JP-A-11-080825 JP 2005-336586 A JP 2007-92158 A

Incidentally, the above Patent Documents 1 to 6 have the following problems.
That is, in the method disclosed in Patent Document 1, it is possible to secure a heat source for melting a large amount of scrap, but since a carbon source for heating (carbon material, etc.) is separately added, An increase in cost is inevitable.

Moreover, since sulfur contained in the carbon material is mixed, the S concentration of the blown steel increases, and the amount of carbon dioxide (CO ₂ ) generated increases.

  In the method disclosed in Patent Document 2, CO generated in the converter and oxygen blown by the lance are combusted on the bath surface of the hot metal, so that the furnace refractory is very worn.

In the method disclosed in Cited Document 3, although the melting point of CaO is lowered by Al ₂ O ₃ to be added and the hatching of CaO can be promoted, the Al ₂ O ₃ concentration in the slag is increased. This leads to wear and tear of the product, and there is a concern that the cost will increase, and the dephosphorization rate will decrease.

  Furthermore, in the methods disclosed in the cited documents 4, 5 and 6, an upper blowing lance having a quadruple pipe or a five-pipe structure is used and a dephosphorizing agent or the like is conveyed by oxygen gas. Reactive powder containing cannot be blown. In addition, the blowing amount and the flow rate of propane are low, and a sufficient effect cannot be expected to reduce the hot metal mixing ratio.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a powder blowing lance that can efficiently impart (heat) the combustion heat of the burner to the molten iron without the above-described problems, and to advantageously reduce the hot metal blending ratio, and the blowing thereof. The present inventors propose a method for refining molten iron using a lance and a method for melting and reducing molten metal.

The present invention provides a refining oxygen gas injection nozzle having a plurality of injection openings for arranging oxygen gas into an iron bath accommodated in an iron bath type smelting furnace, arranged at intervals along a circular track, and the circular shape A jet opening having an axis that is coaxial with the central axis of the orbit, forming a flame inside the oxygen gas blowing nozzle for refining, and blowing the powder that has been heated by the flame into the iron bath In a powder blowing lance provided with a burner nozzle having a burner function, the index F indicating the positional relationship between the oxygen gas blowing nozzle for scouring and the burner nozzle satisfies the following conditions: Is a powder blowing lance to which
F = 1.7 (R−r−d / 2) / L + tan (θ−12 °) −0.0524> 0

R: Radius (mm) of pitch circle of oxygen gas blowing nozzle for scouring
r: Opening radius of the burner nozzle (mm)
d: Diameter of scouring oxygen nozzle (mm)
θ: Angle (inclination) (°) between the axis of scouring oxygen and the center axis of the circular trajectory
L: Lance height (mm)

  In the powder blowing lance having the burner function configured as described above, it is possible to solve the problem by applying the powder blowing lance as an upper blowing lance for refining used for dephosphorization blowing or decarburization blowing. Preferred as a specific means for

  Further, the present invention provides a method for refining molten iron accommodated in an iron bath type smelting furnace using the powder blowing lance having the above-described configuration, wherein propane gas, C gas or the like is used as fuel for the burner nozzle. A method for refining molten iron using a powder blowing lance provided with a burner function, wherein one or more of gaseous fuel, liquid fuel such as heavy oil, and solid fuel such as plastic are used.

  Furthermore, the present invention is a smelting reduction method for obtaining a molten metal by charging a metal oxide or oxide-based ore powder or granule into the iron bath type smelting furnace and obtaining a molten metal by the above-mentioned configuration. A smelting reduction method characterized by blowing one or more powdery auxiliary materials out of iron oxide, a solvent and a carbon-containing substance through a burner nozzle of a powder blowing lance.

  According to the powder blowing lance imparted with the burner function according to the present invention, the index F indicating the positional relationship between the scouring oxygen gas blowing nozzle and the burner nozzle is expressed as F = 1.7 (R−r−d). /2)/L+tan(θ-12°)−0.0524>0, so that the interference between the refining oxygen gas and the flame formed by the burner is reduced, and the temperature of the burner flame is kept high. Therefore, the powder is efficiently heated, and as a result, the heat receiving efficiency in the molten iron can be improved.

Moreover, according to the powder blowing lance provided with the burner function having the above-described structure, since the heat receiving efficiency to the molten iron is improved, as an upper blowing lance for refining used for dephosphorization blowing or decarburization blowing By using it, scrap can be used in large quantities, and the hot metal blending ratio can be greatly reduced. In addition, the amount of carbon material used can be reduced by improving the heat receiving efficiency, and the amount of CO ₂ emission can be reduced.

  Further, according to the powder blowing lance according to the present invention, one or two kinds of fuels for the burner nozzle, such as gas fuel such as propane gas and C gas, liquid fuel such as heavy oil, and solid fuel such as plastic, etc. By using the above, the molten iron accommodated in the iron bath type smelting furnace can be refined.

  Furthermore, according to the powder blowing lance of the present invention having the above-described configuration, one or more of iron oxide, a solvent and a carbon-containing substance are passed through the burner nozzle of the powder blowing lance. The molten metal can be melt-reduced by blowing the powdery auxiliary material.

It is the figure which showed the state which installed the powder blowing lance according to this invention in the converter type refining equipment. (a) (b) is the figure which showed typically the specific structure of the powder blowing lance according to this invention. It is the figure which showed the relationship between powder temperature and F value.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a view showing a state where a powder blowing lance according to the present invention is installed in a converter type refining facility, and FIGS. 2 (a) and 2 (b) are front end portions of the powder blowing lance according to the present invention. It is the figure which expanded and showed the cross section of.

  Reference numeral 1 in the figure denotes a furnace body. The furnace body 1 is composed of an iron skin 1a that forms a skeleton of the furnace body 1, and a refractory layer 1b that is constructed inside the iron skin 1a.

  Reference numeral 2 is provided at the bottom of the furnace body 1, and a bottom blowing tuyere 3 for stirring an iron bath by blowing an inert gas such as Ar gas during refining is housed in the furnace body 1. Molten iron, 4 is a slag that floats on the molten iron, and 5 is a powder blowing lance (upper blowing lance) that is arranged in a standing posture with its tip directed downward.

  At the upper end of the powder blowing lance 5, a feed pipe 6 for supplying refining oxygen gas, a feed pipe 7 for supplying combustion oxygen gas, a feed pipe 8 for supplying fuel gas, and powder are supplied. The feed pipes 9 are connected to each other.

  Further, reference numeral 10 denotes a powder blown from the upper blowing lance 5, 11 denotes a flame formed by combustion of fuel, and 12 denotes a refining oxygen gas blown together with the powder 10.

  As shown in FIGS. 2 (a) and 2 (b), the powder blowing lance 5 includes a lance main body 5a and a nozzle portion 5b integrally connected to the tip of the lance main body 5a. ing.

Lance body 5a includes an outer tube 5a ₁ having a cooling water circulation path m, consisting of the inner tube 5a ₂ which is concentrically arranged to form a blowing path refining oxygen gas to the inside of the outer tube 5a _1.

Further, the nozzle portion 5b, and the refining oxygen gas blowing nozzle 5b ₁ for blowing oxygen gas into the iron bath contained in the furnace body 1, is provided with the burner nozzle 5b _2, the powder 10, the inner It is blown with carrier gas such as an inert gas through passages formed in the innermost tube 5a _2.

Inside the inner pipe 5a ₂ of the lance body 5a, the pipe bodies 5a ₃ and 5a ₄ for forming a path for supplying the oxidizing gas for combustion and a path for supplying the fuel may be appropriately concentrically arranged. it can. In this case, pipe 5a ₄ located innermost forms a feeding path of the powder.

The refining oxygen gas injection nozzle 5b ₁ includes a plurality of injection openings e that are arranged at intervals along the circular track K (see FIG. 2B) and connect to the refining oxygen gas injection path. ing.

Further, the burner nozzle 5b ₂ has the axis J to become the center axis K ₁ and coaxial circular path K, form a flame 11 inside the radial direction of the ejection openings e of the refining oxygen gas blowing nozzle 5b ₁ In addition, an ejection opening f is provided for blowing the powder 10 that has been heated by the flame 11 into the iron bath.

  The circular trajectory K is displayed as a virtual line, and when the axis of the ejection opening e is on the circular trajectory K, the circular trajectory K is referred to as a pitch circle of the ejection opening e. .

Here, the radius of the pitch circle in the ejection opening e of the scouring oxygen gas blowing nozzle 5b ₁ is R (mm), the radius of the ejection opening f of the burner nozzle 5b ₂ is r (mm), and the scouring oxygen nozzle 5b ₁ has a radius of r (mm). the diameter of the ejection opening e d (mm), and the axis d ₁ of the ejection openings e of scouring oxygen gas blowing nozzle 5b _1, the angle (tilt angle) between the center axis K ₁ of the circular trajectory theta (°) When the lance height (the height from the iron bath surface to the tip of the lance nozzle) is L, the oxygen gas blowing nozzle 5a for refining and the burner nozzle 5b indicate the positional relationship and indicate an index. Assuming F, the condition of F = 1.7 (R−d−2) / L + tan (θ−12 °) −0.0524> 0 is satisfied.

Hereinafter, regarding the powder blowing lance having the above-described configuration, the positional relationship between the refining oxygen gas blowing nozzle 5b ₁ and the burner nozzle 5b ₂ is expressed as F = 1.7 (R−r−d / 2) / L + tan. The process leading to (θ-12 °) −0.0524> 0 will be described.

  First, the inventors, when blowing metal oxide or oxide-based powder through a lance, heating the powder that is blown in advance before contacting the molten iron reduces the hot metal content. We thought that it would be effective, and proceeded with investigations on powder heating and addition methods.

In order to investigate the heating condition of the powder, a vertical tubular furnace having an inner diameter of 1 m and a height of 3 m is used, and a burner function capable of supplying powder from the center to the upper part of the vertical tubular furnace. Using the various top blowing lances having the conditions shown in Table 1 above, a powder blowing experiment (using lime with a size of ≦ 75 mm) was conducted, and the temperature of the powder applied to the spray was radiated. Measurement was performed using a thermometer.

The result is shown in FIG. From the results shown in FIG. 3, for each powder blowing lance, a refining oxygen gas blowing nozzle 5b _1, the positional relationship of the burner nozzle _{5b 2, F = 1.7 (R} -r-d / 2) / L + tan By making (θ−12 °) −0.0524> 0, it has been found that the temperature of the powder is remarkably increased.

  The above conditions are calculated from the trajectory of the jet of the burner gas and the refining oxygen gas, and the temperature of the burner flame decreases when the oxygen gas for refining contacts (interferences) with the burner flame excessively. This is based on the idea, and as a result, the interference between the refining oxygen gas and the burner flame is reduced, and the temperature of the burner flame is kept high, so that the powder is efficiently heated.

  According to the present invention, when performing dephosphorization refining (blowing) or decarburization refining while blowing up blown oxygen gas for refining, the powder as an auxiliary material is efficiently heated by the flame of the burner. However, it becomes possible to supply molten iron, and a large amount of scrap can be melted compared to the conventional case.

  As a result, it is possible to reduce the melting cost for dephosphorization and decarburization refining, and resource saving and energy saving are achieved. Further, since the converter operation can be stabilized, an industrially beneficial effect is brought about.

  The F value is preferably 0.20 as the upper limit from the viewpoint of preventing refractory melting due to secondary combustion of the refining oxygen gas.

  The lance height L is set to about 1000 to 5000 mm in the converter operation.

  As the molten iron to be processed using the powder blowing lance according to the present invention, molten iron produced in hot metal production equipment such as a blast furnace (molten iron used in the dephosphorization process) or dephosphorized molten iron that has undergone the dephosphorization process is preferable.

  In the refinement of molten iron, one or more of gaseous fuel such as propane gas and C gas, liquid fuel such as heavy oil, and solid fuel such as plastic can be used as fuel for the burner nozzle.

  In addition, when a metal oxide or oxide-based ore powder or granule is placed in an iron bath type smelting furnace and melted and reduced to obtain a molten metal, a carbonaceous material and a reducing agent are used to reduce the oxide. It is necessary to add a carbon material for compensating heat.

  As the top blowing lance, the lance having the structure shown in FIG. 2 is used, and the composition shown in Table 2 is obtained in the top bottom blowing converter as shown in FIG. The resulting hot metal was charged together with iron scrap and dephosphorized under the conditions shown in Table 3.

  After that, the slag was discharged and discharged, and the dephosphorized hot metal, which was dephosphorized in the same top-bottom blowing converter, was charged together with iron scrap, decarburized and blown under the conditions shown in Table 3, The effect of the F value of the lance on the hot metal content was investigated. The results are shown in Table 4.

  In dephosphorization blowing, after iron scrap is charged into the furnace, molten iron with a temperature of 1350 ° C. is charged, and smelting oxygen gas is supplied from the top blowing lance. While blowing propane gas toward the molten iron surface, argon gas was blown into the molten iron from the bottom blowing tuyere as a stirring gas.

Also, in this smelting, the amount of iron scrap charged is adjusted so that the dephosphorization end temperature is 1400 ° C., and quick lime has a basicity of slag in the furnace (mass% CaO / mass% SiO ₂ ). The amount added was adjusted to 2.5.

  In decarburization blowing, after iron scrap is charged into the furnace, molten iron (dephosphorized molten iron) with a temperature of 1350 ° C is charged, smelting oxygen gas is supplied from the top blowing lance, and at the same time quick lime While blowing combustion oxygen gas and propane gas toward the molten iron surface, argon gas was blown into the molten iron from the bottom blowing tuyere as a stirring gas.

The amount of iron scrap charged was adjusted so that the decarburization end temperature was 1680 ° C. and the carbon concentration was 0.05 mass%. The addition amount of quicklime was adjusted so that the basicity (mass% CaO / mass% SiO ₂ ) of the slag in the furnace would be 3.5.

  As apparent from Table 4, when dephosphorization and decarburization blowing were performed using the blowing lance having the burner function according to the present invention, the iron scrap blending ratio can be increased. It was confirmed that the mixing ratio can be greatly reduced.

Moreover, in order to perform the smelting reduction of the molten metal using the blowing lance according to the present invention, 2.5 t of molten iron was charged into the converter, the amount of oxygen gas for refining: 7.5 Nm ³ / min, bottom blowing nitrogen gas An amount of 0.25 Nm ³ / min was used to start the smelting while appropriately supplying coke.

  And it heated up until the hot metal temperature reached 1600 degreeC, and when the hot metal temperature reached 1600 degreeC, supply of the chromium ore powder was started from the top blowing lance, and the smelting reduction blowing was implemented. In this smelting reduction blowing, the supply of propane gas and oxygen gas from the burner from the top blowing lance was started simultaneously with the start of smelting reduction blowing.

The flow rate of propane gas and oxygen gas, respectively and 0.2Nm ³ /min,1.0Nm ³ / min, during the smelting reduction blowing, the appropriate hot metal temperature is measured, the hot metal temperature 1600 ° C. which are suitable for smelting reduction In this way, blowing was carried out while changing the supply rate of the chrome ore powder.

  After a predetermined time (about 30 minutes), the supply of chromium ore powder, propane gas, and oxygen gas was stopped, and further blowing for supplying only the top-blown oxygen gas was performed for 3 minutes.

In the above-mentioned smelting reduction blowing, the results of investigation on the relationship between the chromium ore usage index and the F value are shown in Comparative Example (Comparative Examples 3 and 4, blowing conditions are the same as in Compliance Example 4 and Compliance Example 5). It shows in Table 5 with a result. In addition, the usage-amount index of the chromium ore in a table | surface is displayed by comparing with the index of the adaptation example 5 being 1.00.

  As is clear from Table 5, it was confirmed that in Comparative Examples 3 and 4 in which the F value was 0 or less, the usage index of chromium ore in smelting reduction blowing was reduced.

  According to the present invention, since the combustion heat of the burner can be efficiently transmitted to the molten iron through the powder, it is possible to improve the heat receiving efficiency in the molten iron, and in performing dephosphorization refining and decarburization refining in the converter. By using a large amount of scrap, the hot metal content can be greatly reduced.

Further, according to the present invention, it is possible to reduce the amount of carbon material used by improving the heat receiving efficiency, and to reduce the CO ₂ emission amount.

DESCRIPTION OF SYMBOLS 1 Furnace 1a Iron skin 1b Refractory layer 2 Bottom blowing tuyere 3 Molten iron 4 Slag 5 Powder blowing lance 5a Lance main body 5a ₁ Outer pipe 5a ₂ Inner pipe 5a ₃ pipe 5a ₄ pipe 5b Nozzle part 5b ₁ Refinement Oxygen blowing nozzle 5b ₂ burner nozzle
6 Feeding pipe for supplying refining oxygen gas 7 Feeding pipe for supplying combustion oxygen gas 8 Feeding pipe for supplying fuel gas 9 Feeding pipe for supplying powder 10 Powder 11 Flame 12 Oxygen gas for refining e Spout opening f Spout opening

Claims (4)

A refining oxygen gas injection nozzle having a plurality of injection openings for injecting oxygen gas into an iron bath accommodated in an iron bath type smelting furnace, arranged at intervals along the circular orbit, and a central axis of the circular orbit A burner nozzle having an axial core that is coaxial with the refining oxygen gas blowing nozzle and forming a flame inside the refining oxygen gas blowing nozzle, and having a blowing opening for blowing the powder heat-heated by the flame into the iron bath In a powder blowing lance with
A powder blowing lance provided with a burner function, wherein an index F indicating a positional relationship between an ejection opening of the scouring oxygen gas blowing nozzle and an ejection opening of the burner nozzle satisfies the following condition.
F = 1.7 (R−r−d / 2) / L + tan (θ−12 °) −0.0524> 0

R: Radius (mm) of pitch circle of ejection opening of oxygen gas blowing nozzle for scouring
r: Radius of the ejection opening of the burner nozzle (mm)
d: Diameter of the ejection nozzle of the scouring oxygen nozzle (mm)
θ: Angle (inclination) (°) between the axis of the scouring oxygen gas injection nozzle and the central axis of the circular locus
L: Lance height (mm)   A powder blowing lance provided with a burner function, wherein the powder blowing lance according to claim 1 is an upper blowing lance for refining used in dephosphorization or decarburization refining. In the method of refining the molten iron accommodated in the iron bath type smelting furnace using the powder blowing lance according to claim 1 or 2,
As a fuel for the burner nozzle, one or more of gaseous fuels such as propane gas and C gas, liquid fuels such as heavy oil, and solid fuels such as plastics are used. In a smelting reduction method of charging a metal oxide, oxide-based ore powder or granule into an iron bath type smelting furnace and obtaining a molten metal by melting and reducing,
A metal characterized by blowing one or more powdery auxiliary materials out of iron oxide, a solvent and a carbon-containing substance through a burner nozzle of a powder blowing lance according to claim 1. Melting reduction method for molten metal.

Images