CN113462849B - Dephosphorization manganese-protection slagging process for smelting high-phosphorus high-manganese molten iron by converter - Google Patents
Dephosphorization manganese-protection slagging process for smelting high-phosphorus high-manganese molten iron by converter Download PDFInfo
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- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
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- 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
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- 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
- C21C7/0006—Adding metallic additives
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- 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
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C37/10—Cast-iron alloys containing aluminium or silicon
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Abstract
The invention discloses a dephosphorization, manganese-preservation and slagging process for smelting high-phosphorus high-manganese molten iron by a converter, which comprises the steps of ensuring the heat balance in the blowing process in the charging stage and controlling BaO (CaO) -SiO in the initial stage 2 P removal and P fixation of FeO slag system 2 O 5 Middle term improvement of BaO solid P 2 O 5 And the two-dimensional alkalinity CaO/SiO of the slag is controlled at the later stage 2 Reducing the manganese metal in the free manganese oxide at the end point so as to realize dephosphorization, manganese protection and slagging of the high-phosphorus high-manganese molten iron in the blast furnace smelting. The invention utilizes Ba formed by barium metal stronger than calcium and lower than oxygen potential of alkaline oxide 3 （PO 4 ） 2 Not easy to be decomposed to fix Ba 3 （PO 4 ） 2 The characteristic in the slag can greatly reduce the slag amount of the converter when smelting the high-phosphorus molten iron, and the reduction condition of the manganese element at the end point is created by adjusting the slag structure and the slagging process to achieve the operation of the dephosphorization, manganese preservation and slagging process, so that the phosphorus element in the high-phosphorus high-manganese molten iron is fully removed, and the manganese element is fully recycled, thereby reducing the smelting cost and effectively utilizing the lean impurity ore resources.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to a dephosphorization, manganese-protection and slagging process for smelting high-phosphorus high-manganese molten iron by using a converter.
Background
The lean iron ore is distributed more but more dispersedly in south Asia and southwest China, and the lean iron ore not only has high contents of harmful elements such as P, S, but also has high contents of valuable elements such as Mn, V, Ti and the like. At present, steel mills in southwest regions adopt imported ores and local lean and impure ores for batching production, and along with the increasing shortage of domestic iron ore resources, the proportion of high-phosphorus high-manganese iron ore for blast furnace smelting is increased continuously, so that the contents of harmful phosphorus elements and valuable manganese elements in blast furnace molten iron are increased continuously, and the contents of 1000m iron ore are increased continuously 3 The phosphorus content in the molten iron produced by the small blast furnace is increased from 0.120% to 0.310%, and the manganese content is increased from 0.35% to 1.35%. Phosphorus is segregated in steel, can increase the temper brittleness and cold brittleness sensitivity of the steel, has large negative influence on the performance of the steel, and is one of harmful elements which must be strictly controlled for smelting clean steel. Therefore, phosphorus is removed as much as possible during the converter smelting. The manganese element is the most important alloy element in steel making, and the manganese element mainly plays a role in improving the mechanical property of steel, increasing the strength, the hardness, the ductility, the wear resistance and the like of the steel. In conclusion, the method fully removes the phosphorus element in the high-phosphorus high-manganese molten iron in the converter smelting process, effectively utilizes the valuable manganese element in the high-phosphorus high-manganese molten iron, reduces the oxidation loss of the manganese element in the converter smelting process, reduces the alloy consumption in the converter steelmaking process, reduces the smelting cost, and effectively utilizes the valuable manganese element in the high-phosphorus high-manganese molten ironGood and poor miscellaneous iron ore resources.
At present, the process for removing phosphorus, protecting manganese and slagging in the process of smelting high-phosphorus high-manganese molten iron by using a converter is not reported in China, and the invention aims to provide the process for removing phosphorus, protecting manganese and slagging in the process of smelting high-phosphorus high-manganese molten iron by using the converter, so that phosphorus in the molten iron at the smelting end point is fully removed and manganese is fully recycled in the process of smelting high-phosphorus high-manganese molten iron by using the converter.
Disclosure of Invention
The invention aims to provide a dephosphorization, manganese-protection and slagging process for smelting high-phosphorus high-manganese molten iron by using a converter.
The invention aims to realize the dephosphorization, manganese-retention and slagging process for smelting high-phosphorus high-manganese molten iron by using a converter, which comprises the steps of ensuring the heat balance in the blowing process in the charging stage, and controlling BaO (CaO) -SiO in the initial stage 2 Solid (P) removal from FeO slag system 2 O 5 ) Middle improvement of (BaO) solid (P) 2 O 5 ) Later stage control of binary basicity (CaO/SiO) of slag 2 ) Reducing free manganese oxide (MnO) and reducing manganese metal in the free manganese oxide at the end point, thereby realizing dephosphorization, manganese preservation and slag formation in the high-phosphorus high-manganese molten iron blast furnace smelting. The method specifically comprises the following steps:
1) adding molten iron and scrap steel into the converter;
2) blowing by a lower oxygen lance, controlling the ignition oxygen pressure to be 0.70-0.80MPa, controlling the lance position of the oxygen lance to blow for 1-1.5min according to 1400-1500 mm, and improving the content of FeO with low melting point in the slag to assist in melting the slag; after 1.5min, the lance position of the oxygen lance is lowered to 1000-1100mm, and the oxygen lance is blown for 4.5min according to the weight ratio of 20-33kg/t Steel 、8-15kg/t Steel 、2.0-3.5kg/t Steel Respectively adding barium carbonate ore, light-burned dolomite and magnesite balls for slagging.
3) Blowing for 13.5-14.5 min after 4.5min at a ratio of 20-25kg/t Steel 、15-20kg/t Steel Respectively adding barium carbonate ore and dolomite in 5 batches for secondary slagging; controlling the binary alkalinity of the slag to be 1.8-2.3, and controlling the reaction (MnO. SiO) in the slag 2 ）+2（Ba 2+ ）=（2BaO·SiO 2 ）+（Mn 2+ ) Proceeding forward to increase free oxygen in slagManganese oxide (MnO) content.
4) Blowing for 13.5-14.5 minutes, reducing the oxygen lance to 200-300 mm, blowing for 30-50 seconds, measuring the temperature, sampling, and tapping at the target component and temperature: controlling the FeO content of the slag to be 8-15%, controlling the carbon content of the slag to be more than 0.07%, controlling the end temperature of the molten steel to be 1660-1675 ℃, and enabling interface reactions of the slag (MnO) + (Fe) = (FeO) + (Mn) and (MnO) + (C) = (CO + (Mn)) to be carried out forward, so as to promote free manganese oxide in the slag to be reduced into the molten steel, thereby realizing the dephosphorization, manganese-protection and slagging process operation of smelting the high-phosphorus and high-manganese molten iron by using the converter.
The converter steelmaking is carried out in a strong oxidizing atmosphere, elements such as manganese, silicon, vanadium, titanium, carbon and the like with lower oxygen potential in molten iron are easy to oxidize and remove and enter slag and flue gas, the recovery of the manganese element in the molten iron is less than 30 percent in the conventional converter smelting operation, and the remaining elements such as silicon, vanadium, titanium, carbon and the like are residual. The invention utilizes the Ba formed by barium which has stronger metal than calcium and lower oxygen potential than alkaline oxide 3 （PO 4 ） 2 Is not easy to be decomposed and fixed (Ba) 3 （PO 4 ） 2 ) The characteristic in the slag can greatly reduce the slag amount of the converter when smelting high-phosphorus molten iron, and the reduction condition of the end point manganese element is created by adjusting the slag structure and the slag forming process to achieve the operation of the dephosphorization, manganese preservation and slagging process, so that the phosphorus content in the molten steel at the smelting end point is below 0.029%, and the recovery rate of manganese in the molten iron is 49-57%.
Compared with the prior art, the Chinese patent with the application number of 200610097440.9, namely a method for simultaneously dephosphorizing and desulfurizing chrome-containing molten iron by utilizing barium carbonate slag, discloses a method for simultaneously dephosphorizing and desulfurizing chrome-containing molten iron by utilizing barium carbonate slag, which is used for the field of molten iron pretreatment, and mainly comprises the steps of heating desilicated chrome-containing pig iron by a high-temperature furnace or an intermediate frequency induction furnace in an air atmosphere at normal pressure, wherein the added barium carbonate slag accounts for 10 percent of the amount of the chrome-containing pig iron, and the barium carbonate slag used in the method is BaCO 3 -FeO-Cr 2 O 3 Prepared with BaO (CaO) -SiO in the invention 2 The smelting slag system of the FeO converter is completely different.
Also, as for the research on the BaCO3 treatment of molten steel in the reduction period of electric arc furnace steel making (2 nd 2 1992. Proc. in the research and application of BaCO3 in steel making (6 th 1984. in steel), which is a new development of barium slag dephosphorization in steel making (iron and steel), the present invention is essentially different from the converter of the present invention in the components, temperature and operation method for smelting high-phosphorus high-manganese molten iron.
The invention has the beneficial effects that:
the dephosphorization, manganese-protection and slagging process for smelting the high-phosphorus high-manganese molten iron by adopting the converter integrates and innovates each stage in the process of smelting the high-phosphorus high-manganese molten iron by the converter, and comprises the steps of controlling the charging ratio of the molten iron scrap steel at the early stage and controlling BaO (CaO) -SiO at the early stage 2 Solid (P) in FeO slag system 2 O 5 ) Middle improvement of (BaO) solid (P) 2 O 5 ) And controlling the binary basicity (CaO/SiO) of the slag in the later period 2 ) And reducing manganese metal in the free manganese oxide by free manganese oxide (MnO) and reducing manganese metal in the free manganese oxide at the end point, so that the phosphorus content in the molten steel at the end point is below 0.029%, and the residual manganese content is increased to 0.78% from 0.17% on average, so that the phosphorus element in the high-phosphorus high-manganese molten iron is fully removed, and the manganese element is fully recycled. Therefore, the blast furnace can greatly utilize the high-phosphorus high-manganese lean miscellaneous ore in southwest to smelt, the smelting cost is reduced, and the lean miscellaneous ore resource is effectively utilized.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to be limiting in any way, and any variations or modifications which are based on the teachings of the present invention are intended to fall within the scope of the present invention.
The invention relates to a dephosphorization, manganese-protection and slagging process for smelting high-phosphorus high-manganese molten iron by a converter, which comprises the following steps of:
1) charging and proportioning of molten iron scrap steel: adding molten iron and scrap steel into the converter, wherein the temperature of the molten iron is 1281-1343 ℃, the charging proportion of the converter scrap steel is less than 17%, and the heat balance in the converting process is ensured.
2) Initial control of BaO (CaO) -SiO 2 Solid (P) is removed from FeO slag system 2 O 5 ): the lower oxygen lance is blown, and the ignition oxygen pressure is controlled to be 0.70-0.80MPa, controlling the lance position of the oxygen lance according to 1400-1500 mm, and improving the content of FeO with low melting point in the slag to flux slag; blowing for 1-1.5min, lowering the position of the oxygen lance to 1100mm, and blowing for 20-33kg/t within 4.5min Steel 、8-15kg/t Steel 、2.0-3.5kg/t Steel Respectively adding barium carbonate ore, light-burned dolomite and magnesite balls for slagging, and controlling BaO (CaO) -SiO according to the content of [ Si ] in molten iron 2 The (BaO) (CaO) content in the FeO slag system makes the slag phase enter BaSiO early 3 And Ca 2 SiO 3 In the primary zone, then with slag (P) 2 O 5 ) Generation (Ba) 3 （PO 4 ） 2 ) And enter the slag.
3) Middle improvement of (BaO) solid (P) 2 O 5 ): after oxygen supply is carried out for 4.5min in the converter, the temperature in the converter rises to above 1450 ℃, the content of BaO in the slag mainly comes from the self decomposition of barium carbonate ore, and the content of BaO in the slag is stabilized, so that the slag phase is maintained at BaSiO 3 And Ca 2 SiO 3 In the primary crystal zone and in the slag (P) 2 O 5 ) Generation (Ba) 3 （PO 4 ） 2 ) Ba is formed in the slag by the fact that barium has stronger metal than calcium and lower oxygen potential than alkaline oxide 3 （PO 4 ） 2 Is not easy to be decomposed and fixed (Ba) 3 （PO 4 ） 2 ) In the slag, the effect of fixing phosphorus is achieved.
4) Later stage control of binary basicity (CaO/SiO) of slag 2 ) And free manganese oxide (MnO) reduction: blowing for 4.5min, and blowing at a rate of 20-25kg/t Steel 、15-20kg/t Steel The barium carbonate ore and the dolomite are respectively added in batches for secondary slagging (the purpose of batch slagging is to ensure stable temperature and stable slagging by feeding according to the temperature condition in the smelting process): wherein barium carbonate ore is added to maintain the content of BaO in the slag and increase PO 4 3- Stability, and prevention of the temperature rise in the furnace from causing the return [ P ]. Dolomite is added to increase the (MgO) content in the slag to prevent the slag from being over-diluted due to low alkalinity. Pure oxygen is supplied to the converter for 13.5 to 14.5 minutes, the binary alkalinity of the slag is controlled to be 1.8 to 2.3, and the reaction (MnO. SiO) in the slag is controlled 2 ）+2（Ba 2+ ）=（2BaO·SiO 2 ）+（Mn 2+ ) Proceeding forward, increasing the free manganese oxide (MnO) content of the slag.
5) End-point reduction of manganese metal in free manganese oxide: blowing for 13.5-14.5 minutes, reducing the blowing time of the oxygen lance to 200-300 mm for 30-50 seconds, measuring the temperature, sampling, and tapping at the target component and temperature: controlling the FeO content of the slag to be 8-15%, controlling the carbon content of the slag to be more than 0.07%, controlling the end temperature of the molten steel to be 1660-1675 ℃, and enabling steel slag interface reactions (MnO) + (Fe) + (FeO) + (Mn) and (MnO) + (C) = CO + (Mn) to be carried out forward, so as to promote free manganese oxide in the slag to be reduced into the molten steel, thereby realizing the dephosphorization, manganese-protection and slagging process operation of smelting high-phosphorus and high-manganese molten iron by using a converter.
The molten iron comprises 3.4-4.3wt% of chemical components C, 0.22-0.47wt% of Si, 0.93-1.35wt% of Mn, 0.273-0.310wt% of P, less than or equal to 0.035wt% of S and the balance of Fe and inevitable impurities.
The chemical components of the scrap steel comprise 0.17-0.25wt% of C, 0.17-0.48wt% of Si, 0.35-1.47wt% of Mn, 0.025-0.041wt% of P, 0.020-0.043wt% of S, and the balance of Fe and inevitable impurities.
In the barium carbonate ore, the BaO content is more than 45 percent.
The content of MgO in the light-burned dolomite is more than 35 percent so as to reduce the amount of slag.
In the magnesite ball, the MgO content is more than 65% so as to reduce the slag amount.
Example 1
A. According to 945kg/t Steel The molten iron charging proportion is that the following molten iron with the mass ratio of 1332 ℃ is added into a 50 ton converter: 3.81wt% of C, 0.39wt% of Si, 1.12wt% of Mn, 0.273wt% of P, 0.032wt% of S, and the balance of Fe and inevitable impurities; according to 145kg/t Steel The steel scrap charging proportion is that the following steel scrap in mass ratio is added into a 50-ton converter: 0.18wt% of C, 0.42wt% of Si, 0.87wt% of Mn, 0.031wt% of P, 0.026wt% of S, and the balance of Fe and inevitable impurities.
B. Blowing is carried out on the lower oxygen lance, the ignition oxygen pressure is 0.70MPa, and the position of the oxygen lance is 1400 mm. After 1.5min, the position of the oxygen lance is reduced to 1000mm, and barium carbonate (BaCO) is added within 2.5 min 3 83 percent of content), lightly calcined dolomite, magnesite balls and barium carbonate ore, wherein the addition amount of the dolomite is 25kg/t steel, and the addition amount of the dolomite is 13kg/t steel Steel The adding amount of the magnesite balls is 2.3kg/t steel.
C. After oxygen blowing for 4.5 minutes, adding barium carbonate ore and dolomite in 4 batches for slagging, wherein the addition amount of the barium carbonate ore is 20kg/t steel, maintaining the content of BaO in slag, and improving PO 4 3- Stability, preventing the return [ P ] caused by the temperature rise in the furnace, increasing the content of (MgO) in slag and preventing the slag from being over-diluted due to low alkalinity, wherein the addition amount of dolomite is 15kg/t steel. Pure oxygen is supplied to the converter for 13.7 minutes, the binary alkalinity is controlled to be 1.8, and the reaction (MnO. SiO) in the slag is controlled 2 ）+2（Ba 2+ ）=（2BaO·SiO 2 ）+（Mn 2+ ) Proceeding forward, increasing the free manganese oxide (MnO) content of the slag.
D. And (3) blowing oxygen for 14 minutes till the oxygen supply is finished, reducing the oxygen lance to 900mm for blowing for 30 seconds, measuring the temperature, sampling, and tapping when the target components and the temperature are reached: the method is characterized in that 12% of FeO in slag, 0.08% of carbon content in molten steel and 1665 ℃ of end point temperature are controlled, steel slag interface reaction (MnO) + [ Fe ] = (FeO) + [ Mn ] and (MnO) + [ C ] = CO + [ Mn ] is carried out forward, free manganese oxide in slag is reduced to enter molten steel, the recovery rate of residual manganese in molten iron is 56%, the residual Mn content is 0.61% and the end point P content of a converter is 0.027%, and the phosphorus removal, manganese protection and slag formation process operation of high-phosphorus high-manganese molten iron smelted by the converter is realized.
Example 2
A. According to 927kg/t Steel The molten iron charging ratio is that molten iron with the mass ratio of 1281 ℃ is added into a 50 ton converter: c4.3 wt%, Si 0.22wt%, Mn 1.35wt%, P0.273 wt%, S0.033 wt%, and the balance Fe and inevitable impurities in an amount of 164kg/t Steel The steel scrap charging proportion is that the following steel scrap in mass ratio is added into a 50-ton converter: 0.17wt% of C, 0.48wt% of Si, 1.47wt% of Mn, 0.025wt% of P, 0.043wt% of S, and the balance of Fe and inevitable impurities;
B. blowing is carried out on the lower oxygen lance, the ignition oxygen pressure is 0.75MPa, and the lance position of the oxygen lance is 1500 mm. After the reaction solution is used for 1min,
reducing the position of the oxygen lance to 1100mm, and adding barium carbonate ore (BaCO) within 3 minutes 3 83 percent of content), light-burned dolomite, magnesite balls and 20kg/t of steel of barium carbonate ore, 15kg/t of steel of dolomite and 2.0kg/t of steel of magnesite balls.
C. After blowing oxygen for 4.5 minutes, adding barium carbonate ore and dolomite in 5 batches for slagging, wherein the addition of the barium carbonate ore is 25kg/t of steel, and the addition of the dolomite is 15kg/t of steel. Pure oxygen is supplied to the converter for 14.5 minutes, the binary alkalinity is controlled to be 2.0, and the reaction (MnO. SiO) in the slag is controlled 2 ）+2（Ba 2+ ）=（2BaO·SiO 2 ）+（Mn 2+ ) Proceeding forward, increasing the free manganese oxide (MnO) content of the slag.
D. And (3) blowing oxygen for 14.5 minutes till the end of oxygen supply, reducing the oxygen lance to blow for 50 seconds at 200mm, measuring the temperature, sampling, and tapping when the target components and the temperature are reached: the method is characterized in that the FeO content in the slag is controlled to be 8%, the carbon content in the molten steel is controlled to be 0.06%, the end point temperature is 1675 ℃, the steel slag interface reaction (MnO) + [ Fe ] = (FeO) + [ Mn ] and (MnO) + [ C ] = CO + [ Mn ] is controlled to be carried out forward, free manganese oxide in the slag is reduced to enter the molten steel, the recovery rate of residual manganese in the molten iron is 57%, the residual Mn content is 0.78%, and the end point P content of a converter is 0.029%, so that the phosphorus removal, manganese protection and slag formation process operation of the high-phosphorus and high-manganese molten iron smelted by the converter is realized.
Example 3
A. Proportioning molten iron and scrap steel: according to 927kg/t Steel The molten iron charging proportion is that molten iron with the following mass ratio of 1281 ℃ is added into a 50 ton converter: c3.4 wt%, Si 0.47wt%, Mn 0.93wt%, P0.310 wt%, S0.035 wt%, and the balance Fe and unavoidable impurities; according to 164kg/t Steel The steel scrap charging proportion is that the following steel scrap in mass ratio is added into a 50-ton converter: 0.25wt% of C, 0.17wt% of Si, 0.35wt% of Mn, 0.041wt% of P, 0.020 wt% of S, and the balance of Fe and inevitable impurities.
B. The lower oxygen lance is blown, the ignition oxygen pressure is 0.8MPa, and the lance position of the oxygen lance is 1450 mm. After 1.5min, the position of the oxygen lance is reduced to 1050mm, and barium carbonate ore (BaCO) is added within 3.5 min 3 83 percent) of light-burned dolomite, magnesite balls, the addition of barium carbonate ore is 33kg/t steel, the addition of dolomite is 8kg/t steel, the addition of magnesite balls is 3.5kg/t steel, and BaO (CaO) -SiO2-FeO slag system is controlled according to the content of molten iron [ Si ]The (BaO) (CaO) content of (B) in the slag phase to early enter BaSiO 3 And Ca 2 SiO 3 Primary zone, then with slag (P) 2 O 5 ) Generation (Ba) 3 （PO 4 ） 2 ) And enter the slag.
C. After 5 minutes of oxygen supply of the converter, adding barium carbonate ore and dolomite for slagging in 6 batches, wherein the addition amount of the barium carbonate ore is 20kg/t steel, maintaining the content of (BaO) in slag and improving PO (phosphorus oxide) 4 3- Stability, preventing the return [ P ] caused by the temperature rise in the furnace, increasing the content of (MgO) in slag and preventing the slag from being over-diluted due to low alkalinity, wherein the addition amount of dolomite is 15kg/t steel. The converter supplies oxygen to 13.5 minutes, the binary alkalinity is controlled at 2.3, and the reaction (MnO. SiO) in the slag is controlled 2 ）+2（Ba 2+ ）=（2BaO·SiO 2 ）+（Mn 2+ ) Proceeding forward, increasing the free manganese oxide (MnO) content of the slag.
D. And (3) supplying oxygen to the converter for 13.5 minutes until the oxygen supply is finished, reducing the oxygen lance to 750mm for converting for 45 seconds, measuring the temperature, sampling, and tapping when the target components and the temperature are reached: controlling the content of FeO in the slag to be 15%, the content of carbon in the molten steel to be 0.05% and the end point temperature to be 1660 ℃, controlling the forward direction of steel slag interface reaction (MnO) + [ Fe ] = (FeO) + [ Mn ] and (MnO) + [ C ] = CO + [ Mn ], promoting free manganese oxide in the slag to be reduced into the molten steel, and realizing the dephosphorization, manganese-protection and slag-making process operation of smelting high-phosphorus and high-manganese molten iron by a converter, wherein the recovery rate of residual manganese in the molten iron is 49%, the content of residual Mn is 0.41% and the end point P content of the converter is 0.023%.
Claims (7)
1. A process for removing phosphorus, protecting manganese and slagging in the process of smelting high-phosphorus high-manganese molten iron by a converter is characterized by comprising the steps of ensuring the heat balance in the blowing process in the charging stage and controlling BaO-SiO in the initial stage 2 FeO and/or CaO-SiO 2 P removal and P fixation of FeO slag system 2 O 5 Middle term improvement of BaO solid P 2 O 5 And the later stage controls the binary alkalinity CaO/SiO of the slag 2 And free manganese oxide MnO reduction, and reducing manganese metal in the free manganese oxide at an end point, comprising the following steps:
1) adding high-phosphorus high-manganese molten iron and common scrap steel into the converter;
2) blowing by a lower oxygen lance, controlling the ignition oxygen pressure to be 0.70-0.80MPa, and controlling the blowing at the position of the oxygen lance according to 1400-1500 mm for 1-1.5 min; after 1.5min, the lance position of the oxygen lance is lowered to 1000-1100mm, and the amount of oxygen is controlled to be 20-33kg/t within 4.5min of blowing Steel 、8-15kg/t Steel 、2.0-3.5kg/t Steel Respectively adding barium carbonate ore, light-burned dolomite and magnesite balls for slagging;
3) blowing for 13.5-14.5 min after 4.5min at a rate of 20-25kg/t Steel 、15-20kg/t Steel Respectively adding barium carbonate ore and dolomite in batches for secondary slagging; controlling the binary alkalinity of the slag to be 1.8-2.3;
4) and (3) supplying oxygen to the converter for 13.5-14.5 minutes until the oxygen supply is finished, reducing the oxygen lance to blow for 30-50 seconds at 200-300 mm, measuring the temperature, sampling, and tapping at the target component and temperature: controlling the FeO content of the furnace slag to be 8-15%, controlling the carbon content of the furnace slag to be more than 0.07% and controlling the final temperature of the molten steel to be 1660-1675 ℃.
2. The dephosphorization, manganese-protection and slagging process according to claim 1, wherein the molten iron comprises the following chemical components: 3.4 to 4.3 weight percent of C, 0.22 to 0.47 weight percent of Si, 0.93 to 1.35 weight percent of Mn, 0.273 to 0.310 weight percent of P, less than or equal to 0.035 weight percent of S, and the balance of Fe and inevitable impurities.
3. The dephosphorization, manganese-protection and slagging process according to claim 1, wherein the chemical components of the scrap steel are as follows: 0.17 to 0.25 weight percent of C, 0.17 to 0.48 weight percent of Si, 0.35 to 1.47 weight percent of Mn, 0.025 to 0.041 weight percent of P, 0.020 to 0.043 weight percent of S, and the balance of Fe and inevitable impurities.
4. The dephosphorization, manganese-protection and slagging process according to claim 1, wherein in the step 1, the temperature of molten iron is 1281-1343 ℃, the charging proportion of converter scrap steel is less than 17%, and the heat balance in the blowing process is ensured.
5. The dephosphorizing and manganese-protecting slagging process of claim 1, wherein the BaO content in the barium carbonate ore is more than 45%.
6. The dephosphorization, manganese-protection and slagging process according to claim 1, wherein the MgO content in the light-burned dolomite is more than 35%.
7. The dephosphorization, manganese-protection and slagging process according to claim 1, wherein the MgO content in the magnesite balls is more than 65%.
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