CN117721268B - Dephosphorization slag with excellent phosphorus-rich capability and fluidity for converter steelmaking by double slag method at different temperatures and dephosphorization method - Google Patents
Dephosphorization slag with excellent phosphorus-rich capability and fluidity for converter steelmaking by double slag method at different temperatures and dephosphorization method Download PDFInfo
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- 239000002893 slag Substances 0.000 title claims abstract description 207
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000009628 steelmaking Methods 0.000 title claims abstract description 25
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title description 14
- 229910052698 phosphorus Inorganic materials 0.000 title description 14
- 239000011574 phosphorus Substances 0.000 title description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 76
- 229910052742 iron Inorganic materials 0.000 claims abstract description 33
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 14
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 109
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 30
- 229910052760 oxygen Inorganic materials 0.000 claims description 30
- 239000001301 oxygen Substances 0.000 claims description 30
- 238000007664 blowing Methods 0.000 claims description 26
- 235000013980 iron oxide Nutrition 0.000 claims description 21
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 19
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 19
- 239000004571 lime Substances 0.000 claims description 19
- 229910000831 Steel Inorganic materials 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 18
- 239000010959 steel Substances 0.000 claims description 18
- 238000005261 decarburization Methods 0.000 claims description 17
- 239000010459 dolomite Substances 0.000 claims description 12
- 229910000514 dolomite Inorganic materials 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 238000010079 rubber tapping Methods 0.000 claims description 3
- 239000002699 waste material Substances 0.000 claims description 2
- 238000005187 foaming Methods 0.000 abstract description 4
- 239000000126 substance Substances 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005262 decarbonization Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000378 calcium silicate Substances 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- -1 sinter Chemical compound 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- WETINTNJFLGREW-UHFFFAOYSA-N calcium;iron;tetrahydrate Chemical compound O.O.O.O.[Ca].[Fe].[Fe] WETINTNJFLGREW-UHFFFAOYSA-N 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- GBNXLQPMFAUCOI-UHFFFAOYSA-H tetracalcium;oxygen(2-);diphosphate Chemical compound [O-2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GBNXLQPMFAUCOI-UHFFFAOYSA-H 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 229940078499 tricalcium phosphate Drugs 0.000 description 1
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 1
- 235000019731 tricalcium phosphate Nutrition 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention discloses dephosphorization slag with excellent dephosphorization capability and mobility in converter steelmaking by a double slag method and a dephosphorization method, wherein through controlling dephosphorization process parameters and various chemical components in dephosphorization slag at a dephosphorization end point, according to different temperatures at the dephosphorization end point, on the basis of introducing R=CaO/SiO 2 to represent the binary basicity of the dephosphorization slag and reflecting the dephosphorization capability of the dephosphorization slag, the value of M= (FeO+MnO)/(CaO+MgO) is further introduced, the foaming performance and viscosity of the dephosphorization slag are controlled, so that the dephosphorization slag can be smoothly deslagged, and simultaneously, the ratio of N=R/M is controlled, and the balance of the dephosphorization slag between the dephosphorization capability and mobility is comprehensively reflected. According to different dephosphorization period end temperatures, the R value, the M value and the N value are comprehensively controlled, so that the dephosphorization capability of dephosphorization slag at the dephosphorization period end point is excellent, the content of P 2O5 in dephosphorization slag components is higher, and the content is more than 3%; the dephosphorization rate in the dephosphorization period is high, and the dephosphorization rate of the molten iron reaches more than 50 percent; meanwhile, the dephosphorization slag has excellent fluidity, and the slag pouring rate reaches more than 50%.
Description
Technical Field
The invention relates to the technical field of converter steelmaking, in particular to dephosphorization slag with excellent phosphorus-rich capability and fluidity in converter steelmaking by a double slag method at different temperatures and a dephosphorization method.
Background
The double slag method converter steelmaking process is that desilication and dephosphorization are firstly carried out in a converter, and intermediate deslagging is carried out on dephosphorization slag; and then decarburizing in the same converter, after tapping, carrying out total slag retention on the decarburized slag, carrying out slag splashing protection, shaking the furnace to confirm solidification of liquid slag, adding a proper amount of lime to adjust alkalinity of the dephosphorized slag, adding scrap steel, adding molten iron, and carrying out smelting in the next furnace. The double slag method converter steelmaking process utilizes the thermodynamic condition that the converter smelting early temperature is low and is favorable for dephosphorization reaction, and uses decarburization final slag which is basically not provided with dephosphorization capability due to high temperature in the previous furnace to dephosphorize when the lower temperature in the initial blowing stage of the next furnace. Therefore, the lime which has not reacted in the previous heat is fully utilized, so that the consumption of lime can be greatly reduced, and the emission of carbon dioxide is greatly reduced. The consumption of auxiliary materials such as lime and the like is reduced, and the generation amount of converter slag is also reduced.
However, the dephosphorization rate in the dephosphorization period of the double-slag converter steelmaking process is high, the required alkalinity is high, the deslagging of the dephosphorization slag is smooth, and the required alkalinity is low, so that how to make the dephosphorization slag have excellent phosphorus-rich capacity and good fluidity is the key for smoothly and effectively implementing the double-slag converter steelmaking process.
Disclosure of Invention
The invention aims to provide dephosphorization slag and dephosphorization method with excellent dephosphorization capability and fluidity for converter steelmaking by a double slag method at different temperatures, wherein the dephosphorization rate in the dephosphorization period is higher, and the dephosphorization rate of molten iron reaches more than 50%; the dephosphorization slag at the final point of dephosphorization has excellent phosphorus-rich capability and excellent fluidity, and the slag pouring rate reaches more than 50%; can simultaneously meet the requirements of high dephosphorization rate and smooth deslagging of dephosphorization slag in the steelmaking dephosphorization period of the double-slag method converter.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
Dephosphorization slag with excellent phosphorus-rich capability and fluidity in converter steelmaking by a double slag method at different temperatures comprises the following components in percentage by weight: caO: 30-40%, siO 2: 15-30%, feO: 10-32%, mnO: 3-12%, mgO: 5-10% of unavoidable impurities in balance; wherein the FeO content comprises iron oxides FeO and Fe 2O3, and converting the Fe 2O3 content therein into a corresponding FeO content;
(1) The dephosphorization period end point temperature T is 1300-1350 ℃, and the dephosphorization end slag components also need to satisfy the following relation:
1.3≤R≤2.1，0.7≤M≤1.0，1.5≤N≤2.1；
(2) Dephosphorization period end point temperature: t is more than 1350 ℃ and less than or equal to 1400 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.5≤R≤2.3，0.6≤M≤0.9，2.0≤N≤2.8；
(3) Dephosphorization period end point temperature: t is more than 1400 ℃ and less than or equal to 1450 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.7≤R≤2.5，0.5≤M≤0.8，2.5≤N≤3.5；
Wherein, R=CaO/SiO 2; m= (feo+mno)/(cao+mgo); n=r/M.
In the component design of dephosphorization slag of the double slag method converter steelmaking process at different temperatures, the invention comprises the following steps:
CaO is the most main dephosphorizing component in converter slag, and can be combined with P 2O5 in slag to generate tricalcium phosphate or tetracalcium phosphate. For the double-slag converter steelmaking process, the lower limit of CaO content is controlled to be 30 percent in order to ensure stable dephosphorization effect. However, excessive addition of CaO is easy to form high-melting-point calcium silicate, slag components enter a heterogeneous zone, the viscosity of slag is increased, and the smooth discharge of dephosphorized slag is affected by excessive viscosity of dephosphorized slag in the middle deslagging process, so that the upper limit of CaO content is controlled to be 40%.
SiO 2 is mainly used for stabilizing the physical properties of slag and adjusting the alkalinity of the slag. When the SiO 2 content in the dephosphorization slag is less than 15%, the alkalinity of the dephosphorization slag is too high, the fluidity of the dephosphorization slag is reduced, and the intermediate deslagging is difficult; when the content of SiO 2 in the dephosphorization slag is more than 30%, the alkalinity of the dephosphorization slag is too low, and the dephosphorization rate in the dephosphorization period is reduced. Therefore, according to the different Si contents in the molten iron, the SiO 2 content in the dephosphorization slag is controlled to be 15-30%.
FeO, comprising iron oxides FeO and Fe 2O3, and converting the Fe 2O3 content therein to the corresponding FeO content. Under the action of top-blown oxygen, a part of molten iron is oxidized into FeO or Fe 2O3 and enters the slag, and the addition of the ferric oxide auxiliary material can more directly increase the content of FeO in the slag. The FeO content in the slag can be used for reflecting the oxidizing property of the slag, and the higher the FeO content is, the stronger the oxidizing property of the dephosphorization slag is, and the combination of P element and oxygen in molten iron can be promoted to generate P 2O5, so that the dephosphorization reaction is promoted. Meanwhile, lime added into the converter can generate high-melting-point calcium silicate on the surface of the converter in the process of deslagging, so that further melting of lime is prevented. When the FeO content in the dephosphorization slag is higher, the iron oxide can react with calcium silicate to generate low-melting slag phases such as calcium ferrite and the like, so that lime slaking is promoted, and dephosphorization efficiency is improved. In addition, the higher FeO content can also reduce the viscosity of dephosphorization slag, so that dephosphorization slag can be smoothly discharged in the middle deslagging process. Therefore, in order to realize higher dephosphorization rate of molten iron and smooth deslagging, the lower limit of the FeO content in the dephosphorization slag is controlled to be 10 percent. However, when the FeO content in the dephosphorization slag is too high, the molten iron is excessively oxidized, or the added ferric oxide auxiliary materials are excessive, and the metal Fe is greatly consumed in the iron oxide as valuable metal, so that the iron yield is reduced, and the production cost is increased. In addition, the higher FeO content promotes the oxidation of C in the molten iron, so that a large amount of CO bubbles are easily contained in slag, the dephosphorization slag is seriously foamed, and the dephosphorization slag overflows the converter. Therefore, the FeO content in the dephosphorization slag is not excessively high, and the upper limit is controlled to be 32%.
MnO is partially oxidized by manganese element contained in molten iron, and the other part is from recycled decarburized slag, so that the oxidizing property of the slag is mainly regulated, and the fluctuation of MnO in the dephosphorized slag is generally controlled to be 3-12% according to the Mn content in the molten iron.
MgO, a part of the light-burned dolomite comes from the converter, and the light-burned dolomite plays a role in solidifying the decarbonized slag, so that molten iron splashing in the molten iron mixing process is avoided. And the other part of the magnesium-containing refractory material comes from the inner wall of the converter, so that molten iron and slag are vigorously rolled by the production environment of strong oxygen blowing of the converter, the converter wall is eroded, and part of the magnesium-containing refractory material falls off into slag. The content of MgO in the dephosphorization slag is too low, which indicates that the amount of light burned dolomite added for curing the decarburization slag during slag splashing furnace protection is insufficient, the decarburization slag can be incompletely cured under the condition that the decarburization slag is fully left in the previous furnace, molten iron is easy to splash during molten iron adding, and potential safety hazards are caused, so that the lower limit of MgO content is controlled to be 5%. However, excessive MgO can cause excessive viscosity of slag, and the upper limit of MgO content is controlled to be 10% in order to ensure smooth discharge of dephosphorized slag in the middle deslagging process.
Meanwhile, three relational expressions are defined, which are respectively:
R=CaO/SiO2,M=(FeO+MnO)/(CaO+MgO),N=R/M =(CaO/SiO2)/((FeO+MnO)/(CaO+MgO))。
R is defined as the ratio of CaO/SiO 2, is the binary alkalinity of the dephosphorization slag, and mainly reflects the dephosphorization capability of the dephosphorization slag. When the R value is too small, the phosphorus-rich capacity of the dephosphorization slag is drastically reduced, and enough CaO is not combined with P 2O5 to play a dephosphorization role. When the R value is too large, the dephosphorization slag has stronger dephosphorization capability, but the dephosphorization slag has larger viscosity and poor fluidity, and the dephosphorization slag is difficult to pour out in the middle deslagging process or can be poured out only in a longer time, so that the production efficiency is affected.
M is defined as the ratio of (FeO+MnO)/(CaO+MgO), the sum of FeO and MnO content in the dephosphorization slag reflects the oxidability of the dephosphorization slag and is directly related to the foaming property of the dephosphorization slag, and CaO and MgO are important components for increasing the viscosity of the dephosphorization slag. When the M value is too small, the content of FeO and MnO in the slag is low, the content of CaO and MgO is high, dephosphorization slag is viscous, slag cannot be smoothly discharged, and lime slaking is difficult. When the M value is too large, the content of FeO and MnO in the slag is higher, the content of CaO and MgO is lower, the viscosity of dephosphorization slag is low, slag can be smoothly discharged, but excessive foaming of the dephosphorization slag is easily caused, and the dephosphorization slag overflows the converter.
N is defined as the ratio of R/m= (CaO/SiO 2)/((feo+mno)/(cao+mgo)), where CaO/SiO 2 is a binary alkalinity reflecting the phosphorus rich capacity of the dephosphorized slag and (feo+mno)/(cao+mgo) reflecting the fluidity of the dephosphorized slag. The ratio of (CaO/SiO 2)/((FeO+MnO)/(CaO+MgO)) can more comprehensively and comprehensively reflect the balance between the phosphorus-rich capacity and the fluidity of the dephosphorization slag. When the N value is too large, the dephosphorization slag has excellent phosphorus-rich capability, but poor fluidity and can not smoothly discharge slag. When the N value is too small, the dephosphorization slag has excellent fluidity and can smoothly discharge slag, but the phosphorus-rich capacity of the dephosphorization slag is reduced, and the dephosphorization rate of molten iron at the end of the dephosphorization period is lower.
According to the invention, a great amount of experimental researches show that in the double-slag-method converter steelmaking process, the ratio R, M, N needs to meet different conditions at different temperatures at the dephosphorization period end point.
When the dephosphorization end point temperature T is lower and is 1300-1350 ℃, the dephosphorization reaction is carried out in a thermodynamic manner, a better dephosphorization effect can be achieved by adding less lime, caO in dephosphorization slag can be in a lower content at the moment, but the dephosphorization slag has poor fluidity due to low temperature, and the FeO content in the dephosphorization slag needs to be increased to reduce the viscosity of the dephosphorization slag so as to ensure the smooth intermediate deslagging. Therefore, the R value is lower, the M value is higher, and the N value is lower.
Along with the increase of the dephosphorization period end point temperature, the high temperature is unfavorable for dephosphorization reaction, at the moment, the CaO content in the dephosphorization slag needs to be increased, and meanwhile, the viscosity of the dephosphorization slag is reduced along with the increase of the temperature, so that the dephosphorization slag with lower FeO content in the dephosphorization slag also has excellent fluidity. Therefore, different dephosphorization period end temperature intervals are set, the R value is increased, the M value is reduced, and the N value is increased along with the temperature rise.
The industrial experiment summary of the double slag method converter steelmaking is as follows:
(1) The dephosphorization period end point temperature T is 1300-1350 ℃, and the dephosphorization end slag components also need to satisfy the following relation:
1.3≤R≤2.1，0.7≤M≤1.0，1.5≤N≤2.1；
(2) Dephosphorization period end point temperature: t is more than 1350 ℃ and less than or equal to 1400 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.5≤R≤2.3，0.6≤M≤0.9，2.0≤N≤2.8；
(3) Dephosphorization period end point temperature: t is more than 1400 ℃ and less than or equal to 1450 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.7≤R≤2.5，0.5≤M≤0.8，2.5≤N≤3.5；
The invention also provides a dephosphorization method for converter steelmaking by a double slag method at different temperatures, wherein after tapping at the decarburization end point of the previous converter, 100% of decarburization slag is completely left for next dephosphorization, light burned dolomite is added as a liquid slag curing agent, slag splashing furnace protection is carried out, lime is added to adjust the alkalinity of dephosphorization slag, then waste steel is added first, and molten iron is added; desilication dephosphorization operation is carried out in the dephosphorization period, after the dephosphorization slag is poured out, decarburization operation is carried out in the decarburization period in the same converter, and 100% of the decarburization slag is left for the dephosphorization of the next converter, so that desilication dephosphorization and decarburization operation are circularly carried out;
The dephosphorization slag at the end of the dephosphorization period comprises the following components in percentage by weight: caO: 30-40%, siO 2: 15-30%, feO: 10-32%, mnO: 3-12%, mgO: 5-10% of unavoidable impurities in balance; wherein the FeO content comprises iron oxides FeO and Fe 2O3, and converting the Fe 2O3 content therein into a corresponding FeO content;
(1) The dephosphorization period end point temperature T is 1300-1350 ℃, and the dephosphorization end slag components also need to satisfy the following relation:
1.3≤R≤2.1，0.7≤M≤1.0，1.5≤N≤2.1；
(2) Dephosphorization period end point temperature: t is more than 1350 ℃ and less than or equal to 1400 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.5≤R≤2.3，0.6≤M≤0.9，2.0≤N≤2.8；
(3) Dephosphorization period end point temperature: t is more than 1400 ℃ and less than or equal to 1450 ℃, and the dephosphorization final slag components also need to satisfy the following relation:
1.7≤R≤2.5，0.5≤M≤0.8，2.5≤N≤3.5；
Wherein, R=CaO/SiO 2; m= (feo+mno)/(cao+mgo); n=r/M.
Preferably, the addition amount of the light burned dolomite is 5-10 kg/ton of steel.
Preferably, the addition amount of lime is 5-20 kg/ton of steel.
Preferably, in the dephosphorization period, the oxygen lance is lowered to start high lance position oxygen blowing, the blowing time in the dephosphorization period is 3-10 min, and the top blowing oxygen supply strength is 1.5-3.5 m 3/(t.min); adding iron oxide auxiliary materials in the blowing period, wherein the addition amount is 6-12 kg/ton of steel; before converting in the dephosphorization period is finished, adjusting an oxygen lance to a low lance position, and improving the top-blown oxygen intensity to 2.0-4.0 m 3/(t.min); and lifting the oxygen lance after converting, tilting the converter, and pouring dephosphorization slag into the slag pot.
Preferably, the iron oxide auxiliary materials are sinter, return ore, OG pressed balls or auxiliary materials with main components of iron oxide.
Preferably, the content of P 2O5 in the dephosphorization slag component is higher, and the content is more than 3%.
The dephosphorization rate of the molten iron in the dephosphorization period is improved to more than 50%, and the slag pouring rate at the end of the dephosphorization period is improved to more than 50%.
In the dephosphorization method of the invention, the following steps are carried out:
And (3) fully leaving 100% of liquid decarbonization slag in the previous furnace as a dephosphorizing agent in the next furnace, adding 5-10 kg/ton of light burned dolomite, and performing slag splashing furnace protection operation to ensure that the decarbonization slag is fully solidified. When the addition amount of the light burned dolomite is less than 5 kg per ton of steel, the decarburized slag is possibly incompletely solidified, molten iron is easily splashed when molten iron is added, potential safety hazards are caused, and meanwhile, the MgO content in the dephosphorized slag is far away from the saturation concentration, so that a furnace lining is corroded. When the addition amount of the light burned dolomite is more than 10 kg per ton of steel, the viscosity of dephosphorization slag is too high, and the intermediate slag discharge is difficult to carry out. Then lime is added, the addition amount of lime is 5-20 kg/ton of steel, and then scrap steel is added and molten iron is added.
In the dephosphorization period, the oxygen lance is lowered to start high lance position oxygen blowing, and the blowing time in the dephosphorization period is 3-10 min. The high gun position is used for realizing desilication of the molten iron in the earlier stage, and avoiding the rapid temperature rise of a converter molten pool caused by severe decarburization reaction. When the blowing time in the dephosphorization stage is less than 3 minutes, lime slaking is insufficient, silicon and phosphorus competing reactions in molten iron preferentially perform desilication reaction, and dephosphorization reaction is not started yet. When the blowing time in the dephosphorization stage is longer than 10 minutes, the temperature of molten iron is too high, which is unfavorable for dephosphorization reaction, and meanwhile, the FeO content in dephosphorization slag can be increased by excessive oxygen blowing, so that higher iron loss is caused.
The top blowing oxygen supply strength of the high gun position oxygen blowing dephosphorization stage is 1.5-3.5 m 3/(t.min); adding an iron oxide auxiliary material in the blowing period, wherein the addition amount of the iron oxide auxiliary material is 6-12 kg/ton of steel, and the iron oxide auxiliary material can be an auxiliary material with main components of iron oxide, such as sinter, return ore, OG pressed balls and the like; before converting in the dephosphorization period is finished, an oxygen lance is adjusted to a low lance position, the top-blown oxygen intensity is improved to 2.0-4.0 m 3/(t.min), and the low lance position is simultaneously increased to improve mass transfer in a molten pool and promote dephosphorization reaction; after blowing is finished, the oxygen lance is lifted, the converter is inclined, and dephosphorization slag is poured into the slag pot as much as possible.
Compared with the prior art, the invention has the beneficial effects that:
the traditional dephosphorization slag only considers the control of binary alkalinity, and is difficult to simultaneously meet higher dephosphorization rate and slag pouring rate.
According to the design of dephosphorization slag components adopted by the invention, through controlling various chemical components in the dephosphorization slag, according to different temperatures of a dephosphorization period end point, on the basis of introducing R=CaO/SiO 2 to represent the binary alkalinity of the dephosphorization slag and reflecting the dephosphorization capability of the dephosphorization slag, the value of M= (FeO+MnO)/(CaO+MgO) is further introduced, the foaming performance and viscosity of the dephosphorization slag are controlled, so that the dephosphorization slag can smoothly slag, and simultaneously, the ratio of N=R/M is controlled, and the balance between the phosphorus-rich capability and the fluidity of the dephosphorization slag is comprehensively reflected. According to different dephosphorization period end temperatures, the R value, the M value and the N value are comprehensively controlled, so that the dephosphorization capability of dephosphorization slag at the dephosphorization period end point is excellent, the content of P 2O5 in dephosphorization slag components is higher, and the content is more than 3%; the dephosphorization rate in the dephosphorization period is high, and the dephosphorization rate of the molten iron reaches more than 50 percent; meanwhile, the dephosphorization slag has excellent fluidity, and the slag pouring rate reaches more than 50%.
According to the dephosphorization method, the addition amount of light-burned dolomite, lime and ferric oxide auxiliary materials in the dephosphorization process, the blowing time and the top blowing oxygen supply intensity are controlled, and according to different temperature ranges of the dephosphorization period end point, dephosphorization slag components of the dephosphorization period end point are respectively controlled to meet different controls, so that the requirements of high dephosphorization rate and smooth dephosphorization slag discharge in the dephosphorization period of the double-slag converter steelmaking under different temperatures are met.
Detailed Description
The invention is further illustrated below with reference to examples.
The process control parameters for the inventive examples and comparative examples are shown in table 1. Table 2 shows the dephosphorization slag compositions and the slag removal rates of the examples and the comparative examples of the present invention.
The operation steps of the embodiment of the invention are as follows:
Leaving 100% of liquid decarbonization slag in the previous furnace as dephosphorizing agent in the next furnace, adding 5-10 kg/ton of light burned dolomite, performing slag splashing furnace protection operation to ensure that the decarbonization slag is fully solidified, adding lime to adjust alkalinity, adding lime to 5-20 kg/ton of steel, adding scrap steel and adding molten iron; in the dephosphorization period, the oxygen lance is lowered to start high lance position oxygen blowing, the blowing time in the dephosphorization period is 3-10 min, and the top blowing oxygen supply strength is 1.5-3.5 m 3/(t.min); adding an iron oxide auxiliary material in the blowing period, wherein the addition amount of the iron oxide auxiliary material is 6-12 kg/ton of steel, and the iron oxide auxiliary material can be an auxiliary material with main components of iron oxide, such as sinter, return ore, OG pressed balls and the like; before converting in the dephosphorization period is finished, adjusting an oxygen lance to a low lance position, and improving the top-blown oxygen intensity to 2.0-4.0 m 3/(t.min); after blowing is finished, the oxygen lance is lifted, the converter is inclined, and dephosphorization slag is poured into the slag pot as much as possible.
As shown in Table2, the dephosphorization slag at the dephosphorization end point has excellent phosphorus-rich capability, and the content of P 2O5 in the dephosphorization slag component is higher and is more than 3%; the dephosphorization rate in the dephosphorization period is high, and the dephosphorization rate of the molten iron reaches more than 50 percent; meanwhile, the dephosphorization slag has excellent fluidity, and the slag pouring rate reaches more than 50%. The dephosphorization slag can simultaneously meet the requirements of high dephosphorization rate and smooth deslagging of dephosphorization slag in the steelmaking dephosphorization period of the double-slag method converter.
In comparative example 1, the dephosphorization period end temperature was 1376 ℃, and the corresponding N value was greater than the upper limit of 2.8, which resulted in excessively high viscosity of dephosphorization slag, general fluidity of dephosphorization slag, 29% of slag pouring rate, and difficult intermediate slag removal. The reasons for the production are shown in Table 1, and the iron oxide addition amount is lower than the lower limit of 6 kg/ton steel, which results in insufficient foamability and higher viscosity in the dephosphorized slag.
In comparative example 2, the dephosphorization period end point temperature was 1432 ℃, the corresponding R value was less than the prescribed lower limit of 1.7, and the N value was less than the prescribed lower limit of 2.5, resulting in insufficient CaO in the dephosphorization slag for dephosphorization, and the dephosphorization rate was low, only 35%. This is because a higher basicity is required to ensure a higher dephosphorization rate of molten iron at a high temperature of 1400 c or higher.
The present invention is further described above by way of examples, but the present invention is not limited to the above-described examples, and various changes, modifications, substitutions, combinations or simplifications made under the spirit and principle of the technical scheme of the present invention can be made according to the purpose of the present invention, and all the changes, modifications, substitutions, combinations or simplifications should be equivalent to the manner of substitution, so long as the purpose of the present invention is met, and all the changes are within the scope of the present invention without departing from the technical principle and the inventive concept of the present invention.
Claims (6)
1. A dephosphorization method for converter steelmaking by a double slag method at different temperatures is characterized in that after tapping at the decarburization end point of a previous converter, 100% of decarburization slag is completely left for next dephosphorization, light-burned dolomite is added as a liquid slag curing agent, slag splashing furnace protection is carried out, lime is added to adjust the alkalinity of dephosphorization slag, then waste steel is added first, and molten iron is added; desilication dephosphorization operation is carried out in the dephosphorization period, after the dephosphorization slag is poured out, decarburization operation is carried out in the decarburization period in the same converter, and 100% of the decarburization slag is left for the dephosphorization of the next converter, so that desilication dephosphorization and decarburization operation are circularly carried out;
The dephosphorization slag at the end of the dephosphorization period comprises the following components in percentage by weight: caO: 30-40%, wherein the content of SiO 2：15~30%,FeO：10~32%,MnO：3~12%,MgO：5~10%,P2O5 is more than 3%, and the balance is unavoidable impurities; wherein the FeO content comprises iron oxides FeO and Fe 2O3, and converting the Fe 2O3 content therein into a corresponding FeO content;
(1) The dephosphorization end point temperature T is 1300-1350 ℃, and dephosphorization slag components at the dephosphorization end point also need to satisfy the following relations:
1.3≤R≤2.1，0.7≤M≤1.0，1.5≤N≤2.1；
(2) Dephosphorization period end point temperature: the dephosphorization slag components at 1350 ℃ and less than or equal to 1400 ℃ at the end of the dephosphorization period also need to satisfy the following relations:
1.5≤R≤2.3，0.6≤M≤0.9，2.0≤N≤2.8；
(3) Dephosphorization period end point temperature: the dephosphorization slag components at the end of the dephosphorization period also need to satisfy the following relations:
1.7≤R≤2.5，0.5≤M≤0.8，2.5≤N≤3.5；
Wherein, R=CaO/SiO 2; m= (feo+mno)/(cao+mgo); n=r/M.
2. The dephosphorization method for double slag converter steelmaking at different temperatures according to claim 1, wherein the addition amount of the light burned dolomite is 5-10 kg/ton of steel.
3. The dephosphorization method for double slag converter steelmaking at different temperatures according to claim 1, wherein the lime is added in an amount of 5-20 kg/ton of steel.
4. The dephosphorization method of double slag method converter steelmaking at different temperatures according to claim 1, wherein in the dephosphorization period, oxygen lance is lowered to start high lance position oxygen blowing, the blowing time in the dephosphorization period is 3-10 min, and the top blowing oxygen supply strength is 1.5-3.5 m 3/(t.min); adding iron oxide auxiliary materials in the blowing period, wherein the addition amount is 6-12 kg/ton of steel; before converting in the dephosphorization period is finished, adjusting an oxygen lance to a low lance position, and improving the top-blown oxygen intensity to 2.0-4.0 m 3/(t.min); and lifting the oxygen lance after converting, tilting the converter, and pouring dephosphorization slag into the slag pot.
5. The dephosphorization method for converter steelmaking by a double slag method at different temperatures according to claim 4, wherein the iron oxide auxiliary materials are sinter, return ore, OG pressed balls or auxiliary materials with iron oxide as main components.
6. The dephosphorization method for converter steelmaking by a double slag method at different temperatures according to any one of claims 1 to 5, wherein the dephosphorization rate of molten iron in the dephosphorization period is increased to more than 50%, and the slag pouring rate at the end of the dephosphorization period is increased to more than 50%.
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