CN113774187A - Composite deoxidizer and its preparation and use method - Google Patents
Composite deoxidizer and its preparation and use method Download PDFInfo
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- CN113774187A CN113774187A CN202111068846.5A CN202111068846A CN113774187A CN 113774187 A CN113774187 A CN 113774187A CN 202111068846 A CN202111068846 A CN 202111068846A CN 113774187 A CN113774187 A CN 113774187A
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- 238000000034 method Methods 0.000 title claims abstract description 53
- 239000002131 composite material Substances 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 73
- 239000010959 steel Substances 0.000 claims abstract description 73
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 33
- 239000002893 slag Substances 0.000 claims abstract description 31
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 29
- 230000008569 process Effects 0.000 claims abstract description 27
- 238000010079 rubber tapping Methods 0.000 claims abstract description 24
- 239000012535 impurity Substances 0.000 claims abstract description 23
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 16
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 8
- 229910052742 iron Inorganic materials 0.000 claims abstract description 8
- 229910052751 metal Inorganic materials 0.000 claims abstract description 7
- 239000002184 metal Substances 0.000 claims abstract description 7
- 239000011575 calcium Substances 0.000 claims description 25
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 22
- 229910052791 calcium Inorganic materials 0.000 claims description 22
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 20
- 230000000694 effects Effects 0.000 claims description 16
- 239000008188 pellet Substances 0.000 claims description 13
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 12
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 12
- 239000004571 lime Substances 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 238000007664 blowing Methods 0.000 claims description 11
- 239000003607 modifier Substances 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 229910052786 argon Inorganic materials 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 241000143437 Aciculosporium take Species 0.000 claims 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 238000007670 refining Methods 0.000 abstract description 8
- 229910000532 Deoxidized steel Inorganic materials 0.000 abstract description 5
- 230000015556 catabolic process Effects 0.000 abstract description 4
- 238000006731 degradation reaction Methods 0.000 abstract description 4
- 238000009851 ferrous metallurgy Methods 0.000 abstract description 2
- -1 aluminum compound Chemical class 0.000 abstract 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 25
- 229910052593 corundum Inorganic materials 0.000 description 17
- 229910001845 yogo sapphire Inorganic materials 0.000 description 17
- 229910052799 carbon Inorganic materials 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 150000001875 compounds Chemical class 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 6
- 229910000976 Electrical steel Inorganic materials 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 238000007667 floating Methods 0.000 description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 238000009749 continuous casting Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 229910014813 CaC2 Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000003749 cleanliness Effects 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- ULGYAEQHFNJYML-UHFFFAOYSA-N [AlH3].[Ca] Chemical compound [AlH3].[Ca] ULGYAEQHFNJYML-UHFFFAOYSA-N 0.000 description 2
- NCJRLCWABWKAGX-UHFFFAOYSA-N [Si].[Ca].[Ba] Chemical compound [Si].[Ca].[Ba] NCJRLCWABWKAGX-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001669 calcium Chemical class 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000004925 denaturation Methods 0.000 description 2
- 230000036425 denaturation Effects 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 230000007306 turnover Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 229910000600 Ba alloy Inorganic materials 0.000 description 1
- 229910000882 Ca alloy Inorganic materials 0.000 description 1
- 239000005997 Calcium carbide Substances 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- 235000014653 Carica parviflora Nutrition 0.000 description 1
- 241000243321 Cnidaria Species 0.000 description 1
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- 229910000720 Silicomanganese Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- RGKMZNDDOBAZGW-UHFFFAOYSA-N aluminum calcium Chemical compound [Al].[Ca] RGKMZNDDOBAZGW-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
- 230000024121 nodulation Effects 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000007920 subcutaneous administration Methods 0.000 description 1
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a composite deoxidizer and preparation and use methods thereof, belonging to the technical field of ferrous metallurgy. The invention provides an aluminum composite deoxidizer for improving the problems of poor castability and high inclusion degradation rate of aluminum deoxidized steel, which comprises the following components in percentage by weight: metal aluminum: 60-70%; 7Al2O312CaO pre-slag: 5-15%, calcium carbonate: 10-20%, Fe: 10-20% and the balance of trace impurity elements. The invention provides an aluminum compound deoxidizer by deeply researching the behavior of inclusions in steel after aluminum deoxidation, and the deoxidizer is added in the tapping process of a converter, so that the proportion of large inclusions in the steel can be effectively reduced, the inclusions are modified, the total amount of the inclusions is reduced under the condition of not prolonging the refining time, and the problems of poor castability and high inclusion degradation rate in the production process of the steel at present are solved.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a composite deoxidizer and a preparation and use method thereof.
Background
Aluminum is the most commonly used deoxidizer in the current steel production process. The aluminum and oxygen have strong affinity, high deoxidation efficiency and low cost, and the deoxidation product is easy to float upwards and be removed, so that the aluminum and oxygen are often used as final deoxidizers, and high molten steel cleanliness can be obtained. In addition, deoxidation with aluminium also allows fine-grained steel to be produced relatively economically.
The products of the aluminium deoxidation are mainly solid Al2O3It mainly involves three aspects: 1) al (Al)2O3Nucleation of the particles; 2) al (Al)2O3Aggregation and growth of nucleation particles; 3) al (Al)2O3Separating and removing the inclusions. Al (Al)2O3The quantity, form and size distribution of inclusions in the deoxidized steel have great influence on the cleanliness of molten steel, the blockage of a water gap in the pouring process, the quality of steel and the like, and if the deoxidation is poor, a casting blank can generate subcutaneous air holes and surface defects; excessive deoxidation increases the viscosity of molten steel, deteriorates the fluidity, and produces Al2O3High-melting-point inclusions are easy to accumulate and form nodules on the inner wall of a tundish nozzle to block the nozzle, so that smooth casting is influenced. This is particularly prominent in low carbon, low silicon aluminum killed steels, which are characterized by poor castability, poor cleanliness, or a combination of both. Relevant literature research shows that most domestic manufacturers face a common problem in producing the steel grades.
In the current process, there are three main methods for removing alumina inclusions: firstly, argon is blown into a steel ladle, molten steel stirring is enhanced, floating of inclusions is promoted, but the method needs more time consumption and white slag operation, and the risk of silicon return is caused when low-silicon steel seeds are produced; secondly, feeding calcium alloy into the molten steel to modify the impurities in the alumina. However, the calcium element is active in property and is easy to gasify at the steelmaking temperature, so that the yield of calcium in the calcium treatment process is not high and is only 10-20 percent; meanwhile, the calcium treatment has higher requirement (less than or equal to 0.008 percent or even lower) on the sulfur content in steel; and secondly, the addition amount of calcium is difficult to control, too little calcium is added, a good modification effect cannot be achieved, too much calcium is added, and the calcium can react with sulfur in molten steel to generate CaS inclusion to block a water gap and also react with refractory materials on the wall of a ladle to generate new inclusion. The smelting cost is increased with a high probability and the denaturation effect is not ideal. And thirdly, impurities are removed through vacuum circulation, the impurities are removed in a physical mode with the first way, the impurity removal efficiency is higher than that of the first way, the effective removal rate reaches about 40%, and the cost is obviously not matched with the quality requirement by adopting a vacuum mode when low-carbon aluminum killed steel with general quality is produced.
In addition, CN202011354129.4 discloses a smelting method of high-cleanliness microalloyed high-strength steel, which comprises the working procedures of molten iron pre-desulfurization, converter smelting, LF refining and RH refining. The deoxidation mode of the patent is as follows: one or more of silicomanganese, ferromanganese, calcium carbide, silicon carbide and carburant are selected for deoxidation alloying in the tapping process, the refining process control is mainly emphasized, the adopted deoxidizers are added in combination of conventional deoxidizers, and the combined addition operation is inconvenient.
CN201910134558.1 discloses a method for producing low-carbon low-silicon steel seeds, which comprises the following steps: 1. controlling the end point of the converter; 2. deoxidizing and alloying; 3. slag blocking operation of the converter; 4. operating an argon station; 5. controlling an LF furnace; 6. and (4) continuous casting operation. The method can optimize the deoxidation process of the low-carbon low-silicon aluminum killed steel, further improve the deoxidation effect, reduce high-melting-point inclusions in the steel, avoid the problem of nozzle nodulation of a continuous casting tundish, and solve the quality problem of bubbles of a continuous casting blank caused by insufficient deoxidation; however, the method adopts the processes of calcium treatment and reducing slag making, so that the cost is high and the production time is long.
CN201811416892.8 discloses a deoxidation method for producing low-carbon low-silicon steel by a small converter, which controls the proportion of aluminum and silicon deoxidizers by adding aluminum deoxidizers and silicon deoxidizers, so that the silicon content in the final steel is reduced from 0.10-0.20% to below 0.10%, the silicon content is reduced, the surface quality of steel is improved, the problem of flocculation at a water gap of a crystallizer of a sizing ladle continuous casting machine is not easily caused, and the purity of molten steel is improved. The patent mainly achieves the purpose of controlling the silicon content in the steel by adjusting the addition type and the addition amount of the deoxidizer, and does not relate to inclusion control.
CN201810706078.3 discloses a process for deoxidizing low-carbon low-silicon steel by using barium as a deoxidizing agent, wherein a silicon-calcium-barium alloy is used as the deoxidizing agent in the traditional deoxidizing process, and the adding amount and the adding method of the barium are the same as those of the deoxidizing agent used in the traditional deoxidizing process. The patent adopts the deoxidation alloy as aluminum and silicon calcium barium, and the deoxidation alloy is used for carrying out calcium treatment on the inclusions to achieve denaturation treatment of the inclusions, so that the problems of poor stability and high cost exist.
Disclosure of Invention
Aiming at the problems in the prior art, the invention develops a deoxidizer and a process by deeply researching the behavior of inclusions in steel after aluminum deoxidation so as to effectively reduce the proportion of large-scale inclusions in the steel, modify the inclusions, reduce the total amount of the inclusions under the condition of not prolonging the refining time and improve the problems of poor castability and high inclusion degradation rate in the production process of the steel at present.
The invention firstly provides a composite deoxidizer, which
The composite material comprises the following components in percentage by mass: metal aluminum: 60-70%; 7Al2O312CaO pre-slag: 5-15%, calcium carbonate: 10-20%, Fe: 10-20% and the balance of trace impurity elements.
Wherein the particle size of the composite deoxidizer is 10-35 mm.
The invention also provides a preparation method of the compound deoxidizer, which comprises the following steps:
A. taking the components according to the proportion, grinding the components to be less than 3mm, mixing and stirring the dry materials for 8-11 min, and uniformly mixing;
B. preparing a pellet blank by dry-type pellet pressing by using a powerful pellet press, wherein the pressure is 12-14 GPa, and the specification is 20-35 mm;
C. and screening the pellet blank by adopting a sieve with a sieve pore size not smaller than 10mm, and selecting pellets with a particle size not smaller than 10mm as the composite deoxidizer.
The invention relates to Al according to the aluminum deoxidation process2O3The formation mechanism of the inclusion and the change in the subsequent process also provide a using method of the compound deoxidizer, which comprises the following steps:
A. after the molten steel meets the tapping requirement, adding a compound deoxidizer 2min after tapping according to the oxygen determination result of the converter, and ensuring the bottom blowing effect of a steel ladle during the adding period so that the compound deoxidizer is fully mixed with the molten steel; the addition amount of the composite deoxidizer is 0.78-0.83 kg of composite deoxidizer added per 1ppm of oxygen, and 0.7-0.9 kg of composite deoxidizer per nominal volume weight is additionally added;
B. after the deoxidizing agent is added, adding lime, and keeping argon stirring for a steel ladle during adding;
C. after tapping, adding a calcium top slag modifier to the slag surface, and blowing argon at the bottom of the steel ladle in the adding process without blowing turnover.
In the using method of the composite deoxidizer, in the step B, the addition amount of the lime is 2-3 kg/ton of steel tapping.
In the using method of the composite deoxidizer, in the step C, the calcium top slag modifier comprises the following components in percentage by mass: CaC2：30％～50％，Al2O3: 10-30%, CaO: 20 to 40 percent of the total weight of the alloy, less than or equal to 0.2 percent of S, less than or equal to 0.1 percent of P, and the balance of inevitable impurities.
In the using method of the composite deoxidizer, in the step C, the addition amount of the calcium top slag modifier is 1-2 kg/ton of steel tapping.
The invention has the beneficial effects that:
the invention provides a composite deoxidizer by deeply researching the behavior of inclusions in steel after aluminum deoxidation, and the deoxidizer is added in the tapping process of a converter, so that the proportion of large inclusions in the steel can be effectively reduced, the inclusions are modified, the total amount of the inclusions is reduced under the condition of not prolonging the refining time, and the problems of poor castability and high inclusion degradation rate in the production process of the steel at present are solved.
Detailed Description
The invention researches the behavior of the inclusion in the steel after the aluminum deoxidation according to the Al in the aluminum deoxidation process2O3The mechanism of inclusion formation and changes in subsequent processes are optimized mainly from two aspects:
one is in Al2O3In the production process, seed inclusion is artificially added to capture fine Al2O3So that the mixture is rapidly gathered to form large-size inclusion floating removal capable of floating upwards;
the motion of the inclusions is found to be random. When a certain inclusion has proper diameter and surface area and collides with other inclusions with different diameters, the inclusions can be adsorbed and become the core of the long inclusion, which is technically called as seed inclusion. When other inclusions move around the seed inclusion, the seed inclusion can adsorb the surrounding inclusion particles under the action of viscous force and fluid power. Once the adsorption is successful, the adhered inclusions form protrusions on the surface of the seed inclusions, thereby increasing the volume and surface area of the seed inclusions and providing more favorable conditions for the next adsorption process. Meanwhile, the adsorption of the inclusions has persistence: the adsorbed inclusions tend to become the next "active" surface to adsorb, and these protrusions eventually grow into tentacles of larger size.
The alumina has strong agglomeration and growth effects, and can trap fine alumina generated in the deoxidation process when added into the molten steel, grow up and be easily floated and removed, and the effect is similar to that of water purification by alum. With Al2O3The wetting angle between the inclusion and the molten steel is more than 90 degrees, the inclusion belongs to iron-phobic inclusion, the inclusion and the molten steel can be mutually adhered after collision, and can be quickly sintered into coral community under the action of molten steel static pressure and high temperature, the size reaches more than 100 mu m, even is much larger, and the inclusion and the molten steel can be quickly floated and removed. Therefore, Al2O3Is a good choice for seed inclusion.
Secondly, the impurities are denatured in the deoxidation process. According to the research of removing alumina inclusions by calcium treatment in the current industrial production, the core of the calcium treatment is to provide active Ca components in molten steel, Ca entering the steel is combined with O or S in the steel, and formed CaO is combined with Al2O3The low melting point of the generated aluminum calcium salt is easy to float and mix. The main reaction is as follows:
[Ca]+[O]＝CaO(s) (1)
CaO(s)+Al2O3(s)＝CaO·Al2O3(s) (2)
12CaO(s)+7Al2O3(s)＝12CaO·7Al2O3(l) (3)
therefore, the calcium treatment process is the process of converting the alumina inclusion modification into the aluminum calcium salt. But the alloy treated by calcium has low yield and unsatisfactory modification effect, and designs CaO-Al aiming at the processes of nucleation, collision modification, growth and floating of common inclusions2O3Is pre-melted slag, the slag is CaO and Al2O3The aluminum oxide inclusion removing agent has strong holding capacity, and simultaneously, because the surface tension of the aluminum oxide inclusion and the molten steel is large, the repulsive force of the molten steel to the aluminum oxide inclusion is large, so that the aluminum oxide inclusion removing agent is easy to combine with premelting slag entering the molten steel, and the aluminum oxide inclusion removing effect is researched according to the effect. The principle is as follows: adding CaO-Al into the molten steel while deoxidizing2O3The process is characterized in that pre-melted slag is adopted, after a binary pre-melted phase enters molten steel, alumina inclusions in the steel collide and combine with the aluminum calcium acid salt phases in the molten steel, and are denatured into low-melting-point liquid inclusions, and the low-melting-point liquid inclusions grow and float upwards continuously by taking the low-melting-point liquid inclusions as a core, so that the effect of removing the alumina inclusions is achieved.
Based on the research, the invention provides a low-carbon low-silicon aluminum composite deoxidizer which comprises the following components in percentage by mass: metal aluminum: 60-70%; 7Al2O312CaO pre-slag: 5-15%, calcium carbonate: 10-20%, Fe: 10-20% and the balance of trace impurity elements.
In the low-carbon low-silicon aluminum composite deoxidizer, metal aluminum is used as the deoxidizer and is matched with Als components, and the metal aluminum is controlled to be 60-70% so as to ensure the deoxidizing effect; 7Al2O312CaO can rapidly adsorb deoxidation product Al2O3Inclusion, simultaneously forming large inclusion floating removal, playing a role of seed inclusion, controlling 7Al for ensuring the effects of adsorbing and modifying the inclusion2O312CaO pre-melted slag 5-25%; CaO obtained by high-temperature decomposition of calcium carbonate and deoxidation product Al2O3The inclusion reaction forms CaO-Al with low melting point2O3Impurities are modified, large impurities are formed and quickly float up to be removed, and meanwhile, the impurities are quickly decomposed to be beneficial to forming slag, and the content of the impurities is controlled to be 10-15%; fe increase recombinationThe density of the deoxidizer is prevented from being reduced due to the fact that the deoxidizer quickly floats upwards in molten steel, 10-20% of the deoxidizer is controlled through tests, and the density of the composite deoxidizer is just suitable.
The low carbon and low silicon steel type is not generally too long to control the time of the silicon refining, but other aluminum killed steels are not limited to this. Therefore, in the present invention, 7Al is added2O3The mass percent of 12CaO is reduced to 5-15%, and calcium carbonate is adopted to reduce the cost (7 Al)2O312CaO is approximately 3000 yuan/t; passivated CaO is about 4 times the price of calcium carbonate).
The particle size of the composite deoxidizer is controlled to be 10-35 mm.
The invention also provides a preparation method of the low-carbon low-silicon aluminum composite deoxidizer, which comprises the following steps:
A. taking the components according to the proportion, grinding the components to be less than 3mm, mixing and stirring the dry materials for 8-11 min, and uniformly mixing;
B. preparing a pellet blank by dry-type pellet pressing by using a powerful pellet press, wherein the pressure is 12-14 GPa, and the specification is 20-35 mm;
C. and screening the pellet blank by adopting a sieve with a sieve pore size not smaller than 10mm, and selecting pellets with a particle size not smaller than 10mm as the composite deoxidizer.
In the step A of the preparation method, a proper amount of binding agent can be added according to the requirement.
Based on the research and according to the characteristics of the low-carbon low-silicon aluminum composite deoxidizer provided by the invention, the invention also provides a use method of the low-carbon low-silicon aluminum composite deoxidizer, which comprises the following steps:
A. after the molten steel meets the tapping requirement, adding a compound deoxidizer 2min after tapping according to the oxygen determination result of the converter, and ensuring the bottom blowing effect of a steel ladle during the adding period so that the compound deoxidizer is fully mixed with the molten steel; the compound deoxidizer is added in an amount of 0.78-0.83 kg per 1ppm of oxygen, and 0.7-0.9 kg per nominal volume weight of the compound deoxidizer is additionally added;
B. after the addition of the deoxidizer is finished, adding lime (generally, adding lime as soon as possible after the addition of the deoxidizer is finished), and keeping argon stirring for a steel ladle during the addition;
C. after tapping, adding a calcium top slag modifier to the slag surface, and blowing argon at the bottom of the steel ladle in the adding process without blowing turnover.
The aluminum composite deoxidizer is designed aiming at the conventional aluminum deoxidized steel grade, and is suitable for various specific aluminum deoxidized steel grades in the field. In actual production, tapping of molten steel is required to be controlled according to the conventional standard of aluminum deoxidized steel grade in the field.
In the step B of the method, the addition amount of lime is 2-3 kg/ton steel (steel tapping amount). After the composite deoxidizer is added, lime is generally added immediately, and the effect of adding the lime is to react with the residual deoxidizer Al2O3The inclusion reaction forms CaO-Al with low melting point2O3And (4) impurity inclusion, namely modifying the impurity inclusion and forming large-scale impurity to quickly float and remove. However, if the lime has high melting point and the refining time is not enough, the lime cannot be mixed with Al2O3The impurities are mixed and fully reacted.
In the step C of the method, after tapping is finished, adding 1-2 kg/ton steel (steel tapping amount) of calcium-based top slag modifier to the slag surface to reduce the oxidability of ladle slag and enhance the submerged arc effect; the calcium series top slag modifier comprises the following components in percentage by mass: CaC2：30％～50％，Al2O3: 10-30%, CaO: 20 to 40 percent of the total weight of the alloy, less than or equal to 0.2 percent of S, less than or equal to 0.1 percent of P, and the balance of inevitable impurities.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
In the embodiment, the composition of the deoxidizer adopted is (mass percent): metal aluminum: 62 percent; 7Al2O312CaO pre-slag: 10%, calcium carbonate: 13%, Fe: 14 percent, and the balance of trace impurity elements; the calcium series top slag modifier comprises the following components in percentage by mass: CaC2：55％，Al2O3: 17%, CaO: 27 percent of S is less than or equal to 0.2 percent, P is less than or equal to 0.1 percent, and the balance is inevitable impurities.
The semisteel after vanadium extraction and desulfurization of vanadium and titanium containing iron is taken as a raw material to carry out primary smelting of molten steel, wherein the semisteel comprises 3.54% of C, 0.041% of Mn, 0.063% of P, 0.007% of S, 0.03% of V, trace amounts of Cr, Si and Ti, and the balance of iron and inevitable impurities in percentage by weight.
The method comprises the following specific steps:
A. 236 tons of the semi-steel are added into a top-bottom combined blowing converter with the capacity of 220 tons (nominal capacity), and the semi-steel is primarily smelted into molten steel by utilizing the function of oxygen blowing and decarburization of the top-bottom combined blowing converter. When the molten steel is initially refined to the C content of 0.032 wt%, the Mn content of 0.031 wt%, the P content of 0.0091 wt%, the S content of 0.0086 wt% and the temperature of 1665 ℃, tapping from the thick slag to a ladle;
B. after tapping for 2min, according to the oxygen determination result of 650ppm, 700kg of deoxidizer is added, 500kg of lime (the tapping amount is 221t) is added immediately after the deoxidizer is added, and the whole process is that argon is blown at the bottom of the ladle in large air quantity;
C. 320kg of calcium top slag modifier is added into the steel ladle after tapping is finished, and argon is blown from the bottom of the steel ladle in the adding process, so that the phenomenon of turning over is avoided.
D. The problems of large liquid level fluctuation and poor castability caused by flow change and serious blockage of a water gap are not found in the casting process; the casting blank is sampled and analyzed for T [ O ] (total inclusion index) and inclusion type. T [ O ] resulted in 9.8ppm, and the slab T [ O ] of this type of steel, as in the prior art (deoxidized with ferro-aluminum, added in an amount of 0.9kg ferro-aluminum per 1ppm oxygen, and then an additional 200kg ferro-aluminum), averaged 12.8ppm, with about a 23% reduction in inclusion weight; meanwhile, most of the inclusions are below 2 mu m (increased from about 70 percent of the original process to over 88 percent), and the inclusions larger than 15 mu m are not found.
Claims (7)
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