Efficient dephosphorizing and slagging agent for high-phosphorus molten iron in converter smelting and application of efficient dephosphorizing and slagging agent

Abstract

The invention discloses an efficient dephosphorization slagging agent for high-phosphorus molten iron in converter smelting and application of the efficient dephosphorization slagging agent. The dephosphorization slagging agent is composed of, by mass, 45%-50% of barium carbonate ore, 30%-35% of blast furnace carbon-containing dedusting ash, 20%-25% of bauxite and an adhesive, and the weight of the adhesive is 1.5%-2.0% of the weight of the barium carbonate ore, the weight of the blast furnace carbon-containing dedusting ash and the weight of the bauxite. The dephosphorizing slagging agent provided by the invention can improve slagging conditions in the smelting process of a medium-high phosphorus molten iron converter, improve the phosphorus dissolving and fixing capacity of slag, improve the product quality and reduce the consumption of slagging materials of the converter at the same time; the rephosphorization phenomenon caused by slag carried by molten steel in the tapping process is reduced by utilizing the characteristic that the raw dolomite is large in volume density and can rapidly thicken the slag. The method for converter smelting of medium-high phosphorus molten iron by adopting the dephosphorization slagging agent is simple and reliable, and guarantees are provided for application of low-price medium-high phosphorus ore of enterprises.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a high-efficiency dephosphorizing and slag-removing agent for high-phosphorus molten iron in converter smelting and application thereof. Background Art

[0002] The main problems faced by converters when smelting medium-high phosphorus hot metal (P: 0.200%-0.400%) are the difficulty of slag dephosphorization during the smelting process and the serious problem of phosphorus regeneration at the end. At present, the phosphorus control method of various steel mills in dealing with converter smelting of medium-high phosphorus hot metal is mainly to increase the amount of lime added and a large amount of iron-containing slag materials. The amount of lime added is increased by 10-15kg / t compared with the heat with hot metal P < 0.200%. 钢 , iron-containing slag material increased by 5-8kg / t 钢 The addition of large amounts of lime and iron-containing cold materials will cause insufficient heat in the converter smelting process, and the FeO content in the converter final slag will also increase by about 3% (from 16% to 19%), increasing metal loss and reducing alloy yield. In addition, the phosphorus regeneration of molten steel during the converter steelmaking process also increased by nearly 0.01% (from about 0.009% to about 0.017%), resulting in higher production costs for converter smelting and increased product quality risks.

[0003] The invention aims to provide a high-efficiency dephosphorizing slag agent for converter smelting medium- and high-phosphorus molten iron, so as to reduce production costs. Summary of the invention

[0004] The first object of the present invention is to provide a high-efficiency dephosphorization and slag-forming agent for high-phosphorus molten iron in converter smelting, and the second object of the present invention is to provide an application of the high-efficiency dephosphorization and slag-forming agent.

[0005] The first object of the present invention is achieved in that the dephosphorizing slag agent is composed of barium carbonate ore, blast furnace carbon-containing dust ash, bauxite and a bonding agent, wherein the mass percentages of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite are 45%-50%, 30%-35% and 20%-25% respectively, and the bonding agent is 1.5%-2.0% of the weight of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite.

[0006] The second object of the present invention is achieved by applying the high-efficiency dephosphorization slag-removing agent to high-phosphorus molten iron in converter smelting, and the specific method is: 1) Adding medium-high phosphorus molten iron and scrap steel in a mass ratio of 82-85:15-18 into the converter, wherein the molten iron temperature is 1280-1400℃; 2) After opening the oxygen, lower the oxygen lance to 2.0m on the scale plate, open the oxygen valve and start the ignition operation. Adjust the oxygen pressure to 0.85MPa; when blowing oxygen for 1.0min, lower the oxygen lance to 1.2m and add 12-20kg / t of lime. 钢, Lightly burned dolomite 8-15kg / t 钢 、The dephosphorization slag agent is 8-10kg / t 钢 ; Add 5-8kg / t of lime during blowing for 6-9 minutes 钢 , Lightly burned dolomite 2-5kg / t 钢 , Dephosphorizing slag agent 2-3kg / t 钢 ; Maintain a constant oxygen pressure of 0.85MPa and a constant oxygen lance of 1.2m for blowing for 11-12 minutes, then lower the oxygen lance to a minimum of 1.0m and blow for 1 minute, then turn off the oxygen and stop blowing, measure temperature, and perform sampling and analysis; 3) The smelting end point temperature is controlled at 1645-1655℃, and after the end point P≤0.030wt%, add 1.6-2.4kg / t of raw dolomite 钢 After the steel is discharged.

[0007] The present invention uses three materials, barium carbonate ore, carbon-containing dust ash from blast furnace, and bauxite, to mix and make balls in a certain proportion to replace the iron-containing slag material for slag making. The principle is as follows: ① The stability of BaO produced by the decomposition of barium carbonate ore and P2O5 to form Ba3(PO4)2 is stronger than that of 3CaO•P2O5 formed by the original CaO and P2O5, which can effectively reduce the risk of rephosphorization of molten steel and increase the solubility of P in slag; ② The carbon in the carbon-containing dust ash from blast furnace provides conditions for the thermodynamics and kinetics of dephosphorization reaction; ③ Bauxite mainly exists as a mineral combined in the form of A12O3·SiO2. It is thermally decomposed at about 950°C to produce γ-A1203, which is an active alumina with a loose surface and porous structure and a large specific surface area, which improves the slag-steel interface reaction ability and improves the dephosphorization effect.

[0008] The smelting process of the present invention adheres to the "constant pressure and constant gun" operation. During smelting, except for the 1 minute of ignition and deep blowing 1 minute before the end of smelting, the rest of the smelting time is maintained in the "constant pressure and constant gun" operation mode. Before tapping the converter, 100-300kg of raw dolomite is added to each furnace to thicken the converter final slag before tapping, so as to reduce the amount of slag in the tapping process.

[0009] The beneficial effects of the present invention are: 1) The dephosphorization slag agent provided by the present invention can improve the slag-making conditions in the process of medium-high phosphorus hot metal converter smelting, improve the phosphorus dissolving and fixing capacity of the slag, and reduce the consumption of converter slag-making materials while improving product quality (the consumption of medium-high phosphorus hot metal converter slag-making materials is reduced by >10kg / t 钢 ; converter end point P ≤ 0.028%, converter steel-making process rephosphorization ≤ 0.010%), product quality is controllable.

[0010] 2) The present invention utilizes the characteristics of raw dolomite with large volume density to quickly thicken slag to reduce the rephosphorization phenomenon caused by slag in molten steel during the steelmaking process.

[0011] 3) The method of using the dephosphorization slag-removing agent of the present invention to smelt medium-high phosphorus molten iron in a converter is simple and reliable, which provides a guarantee for the application of low-cost medium-high phosphorus ores in enterprises. DETAILED DESCRIPTION

[0012] The present invention is further described in detail below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention fall within the protection scope of the present invention.

[0013] The invention discloses a highly efficient dephosphorization slag-forming agent for converter smelting medium-high phosphorus molten iron, wherein the dephosphorization slag-forming agent is composed of barium carbonate ore, blast furnace carbon-containing dust ash, bauxite and a binder, wherein the mass percentages of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite are 45%-50%, 30%-35% and 20%-25% respectively, and the binder is 1.5%-2.0% of the weight of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite. The chemical composition weight percentages of the dephosphorization slag-forming agent are: BaCO3 21.5-27.0wt%, CaCO3 19.0-24.0wt%, A12O3 9.0-13.0wt%, SiO2 9.0-14.0wt%, TFe 8.5-10.0wt%, C 4.5-6.0wt%, and the rest are unavoidable inclusions.

[0014] The chemical composition weight percentage of the barium carbonate ore is: BaCO3 45.0-53.0wt%, CaCO3 40.0-48.0wt%, and the rest are inevitable inclusions.

[0015] The chemical composition of the carbon-containing dust removal ash from the blast furnace is as follows: C 14.3-17.2wt%, MgO 2.0-2.5wt%, SiO25.5-6.5wt%, TFe 31.0-34.5wt%, Pb 0.7-0.9wt%, Zn 6.8-8.0wt%, and the rest are unavoidable inclusions.

[0016] The chemical composition weight percentage of the bauxite is: A12O3 50.0-60.0wt%, SiO2 20.0-30.0wt%, and the rest are inevitable inclusions.

[0017] The adhesive is bentonite or water glass.

[0018] The preparation method of the dephosphorizing slag agent is as follows: barium carbonate ore, blast furnace carbon dust ash and bauxite are rolled into raw materials of ≤3 mm, then mixed, bentonite adhesive is added to bond, a ball making machine is used to make mixed balls of 10-30 mm, and the mixed balls are obtained after air drying.

[0019] The present invention also provides a method for smelting medium-high phosphorus molten iron in a converter based on the efficient dephosphorization slag-removing agent, and the method is implemented by the following steps: 1) Add medium-high phosphorus molten iron and scrap steel in a mass ratio of 82-85:15-18 into the converter, wherein the molten iron temperature is 1280-1400℃; 2) After opening the oxygen, lower the oxygen lance to 2.0m on the scale plate, open the oxygen valve and start the ignition operation. Adjust the oxygen pressure to 0.85MPa; when blowing oxygen for 1.0min, lower the oxygen lance to 1.2m and add 12-20kg / t of lime. 钢 , Lightly burned dolomite 8-15kg / t 钢 、The dephosphorization slag agent is 8-10kg / t 钢 ; Add 5-8kg / t of lime during blowing for 6-9 minutes 钢 , Lightly burned dolomite 2-5kg / t 钢 , Dephosphorizing slag agent 2-3kg / t 钢 ; Maintain a constant oxygen pressure of 0.85MPa and a constant oxygen lance of 1.2m for blowing for 11-12 minutes, then lower the oxygen lance to a minimum of 1.0m and blow for 1 minute, then turn off the oxygen and stop blowing, measure temperature, and perform sampling and analysis; 3) The smelting end point temperature is controlled at 1645-1655℃, and after the end point P≤0.030wt%, add 1.6-2.4kg / t of raw dolomite 钢 After the steel is discharged.

[0020] In step 1), the chemical composition of the molten iron is: C 3.5-4.4wt%, Si 0.05-0.50wt%, Mn 0.15-0.40wt%, P 0.200-0.400wt%, S≤0.050wt%, and the rest is Fe and unavoidable inclusions; The chemical composition of the scrap steel is: C 0.17-0.25wt%, Si 0.25-0.45wt%, Mn 0.70-1.30wt%, P≤0.045wt%, S≤0.040wt%, and the rest is Fe and unavoidable inclusions.

[0021] In step 3), the chemical composition of the raw dolomite is: CaO 30.0-38.0wt%, MgO 19.0-29.0wt%, SiO2≤5.0wt%, and the rest is burnt and unavoidable inclusions.

[0022] Example 1 1. Preparation of dephosphorization slag agent: barium carbonate ore, blast furnace carbon dust, and bauxite are rolled into raw materials of ≤3mm and mixed in a ratio of 47:32:21 to obtain a mixture, and then bentonite adhesive is added at 1.5% of the total weight of the mixture. The mixture is made into 10-30mm mixed balls, i.e., dephosphorization slag agent, by using a ball making machine. The mixed balls can be transported to the converter silo for standby use after being air-dried for more than 2 days. The chemical composition weight percentage of the obtained dephosphorization slag agent is BaCO3: 25.4wt%, CaCO3: 21.3wt%, A12O3: 10.2wt%, SiO2: 9.7wt%, TFe: 9.1wt%, C: 5.3wt%, and the rest are unavoidable inclusions.

[0023] 2. Add 112.0t of medium-high phosphorus molten iron (chemical composition C: 4.1wt%, Si: 0.27wt%, Mn: 0.25wt%, P: 0.270wt%, S≤0.023wt%, the rest is Fe and unavoidable inclusions) with a temperature of 1341℃ and 23.0t of scrap steel (chemical composition C: 0.17wt%-0.25wt%, Si: 0.25wt%-0.45wt%, Mn: 0.70wt%-1.30wt%, P:≤0.045wt%, S≤0.040wt%, the rest is Fe and unavoidable inclusions) to a 120t top and bottom combined blowing converter.

[0024] 3. Control of converter smelting process: After completing step 2, open the oxygen and lower the oxygen lance to 2.0m on the scale board, then open the oxygen valve for ignition operation, and adjust the oxygen pressure to 0.85MPa; when blowing oxygen for 1.0min, lower the oxygen lance to 1.2m, and add 14kg / t of lime 钢 , Lightly burned dolomite 12kg / t 钢 , Dephosphorizing slag agent 9kg / t 钢 ; Blowing to Add lime 7kg / t at 8min 钢 , Lightly burned dolomite 3kg / t 钢 , Dephosphorizing slag agent 3kg / t 钢 ; Maintain a constant oxygen pressure of 0.85MPa and a constant oxygen lance at 1.2m for blowing for 12 minutes, then lower the oxygen lance to a minimum depth of 1.0m and blow for 1 minute, then turn off the oxygen and stop blowing.

[0025] 4. End point control of converter smelting: the converter stop blowing temperature is 1647℃, the end point P content is 0.018wt%, and 1.6kg / t of raw white cloud is added 钢 (Chemical composition: CaO: 32.4wt%, MgO: 21.4wt%, SiO2: 3.2wt%, the rest are burnt and unavoidable inclusions.) Then the steel tapping operation is carried out to complete the smelting operation.

[0026] The slag material consumption for this furnace is 49.6kg / t (lime: 21kg / t 钢 , Lightly burned dolomite 15kg / t 钢 , Dephosphorizing slag agent 12kg / t 钢 , Raw dolomite 1.6kg / t 钢 , total 49.6kg / t 钢 )Compared with the original slag material 66kg / t 钢 (Lime: 28kg / t 钢 , Lightly burned dolomite 21kg / t 钢 , iron-containing slag material 17kg / t 钢 , total 66kg / t 钢 )Reduced by 16.4kg / t 钢 ; After deoxidation and alloying, the chemical composition of the molten steel is C: 0.23%, Si: 0.47%, Mn: 1.43%, P: 0.027%, S: 0.024%, V: 0.015%, and the rest is Fe and unavoidable inclusions. The P content of the finished product is 0.027wt%, which is 0.009% higher than the final P content of 0.018wt%, that is, the phosphorus recovery during the steelmaking process is 0.009%. Compared with the original slag making process (lime + light-burned dolomite + ore): the FeO in the final slag of the converter is reduced from 19% to 15.6%, a decrease of 3.4%, and the metal loss is reduced by about 3kg / t 钢 The phosphorus regeneration during the steel-making process was reduced from 0.017% to 0.009%, reducing the phosphorus regeneration of molten steel by 0.008%, and the product quality was further guaranteed.

[0027] Example 2 1. Preparation of dephosphorization slag agent: barium carbonate ore, blast furnace carbon dust ash and bauxite are rolled into raw materials of ≤3mm and mixed in a ratio of 46:32:22 to obtain a mixture, and bentonite binder is added at 2.0% of the total weight of the mixture. The mixture is made into 10-30mm mixed balls, i.e. dephosphorization slag agent, by using a ball making machine. The mixed balls can be transported to the converter silo for standby use after being air-dried for more than 2 days.

[0028] The chemical composition weight percentage of the obtained dephosphorizing slag agent is BaCO3: 23.8wt%, CaCO3: 22.6wt%, A12O3: 10.7wt%, SiO2: 10.3wt%, TFe: 8.7wt%, C: 5.7wt%, and the rest are unavoidable inclusions.

[0029] 2. Add 111.0t of medium-high phosphorus molten iron (chemical composition C: 4.2wt%, Si: 0.42wt%, Mn: 0.27wt%, P: 0.360wt%, S≤0.019wt%, the rest are Fe and unavoidable inclusions) at a temperature of 1327℃ and 24.0t of scrap steel (chemical composition C: 0.17wt%-0.25wt%, Si: 0.25wt%-0.45wt%, Mn: 0.70wt%-1.30wt%, P:≤0.045wt%, S≤0.040wt%, the rest are Fe and unavoidable inclusions) to a 120t top and bottom combined blowing converter.

[0030] 3. Control of converter smelting process: After completing step 2, open the oxygen and lower the oxygen lance to 2.0m on the scale plate, then open the oxygen valve for ignition operation, and adjust the oxygen pressure to 0.85MPa; when blowing oxygen for 1.0min, lower the oxygen lance to 1.2m, and add 17kg / t of lime 钢 , Lightly burned dolomite 12kg / t 钢 , Dephosphorizing slag agent 10kg / t 钢 ; Add 8kg / t lime when blowing for 7 minutes 钢 , Lightly burned dolomite 3kg / t 钢 , Dephosphorizing slag agent 4kg / t 钢 ; Maintain a constant oxygen pressure of 0.85MPa and a constant oxygen lance at 1.2m for blowing for 12 minutes, then lower the oxygen lance to a minimum depth of 1.0m and blow for 1 minute, then turn off the oxygen and stop blowing.

[0031] 4. Control of converter smelting endpoint: converter stop blowing temperature is 1616℃, endpoint P: 0.023wt%; lower the gun again to the lowest 1.0m and blow for 40s until the endpoint temperature reaches 1652℃, then add 1.6kg / t of raw white cloud (chemical composition: CaO: 32.4wt%, MgO: 21.4wt%, SiO2: 3.2wt%, the rest are burnt and unavoidable inclusions.) and then perform steel tapping to complete the smelting operation.

[0032] The slag material consumption of this furnace is 55.7kg / t 钢 (Lime: 25kg / t 钢 , Lightly burned dolomite 15kg / t 钢 , Dephosphorizing slag agent 14kg / t 钢 , Raw dolomite 1.7kg / t 钢 , total 55.7kg / t 钢 ), compared with the original slag material 66kg / t 钢 (Lime: 28kg / t 钢 , Lightly burned dolomite 21kg / t 钢 , iron-containing slag material 17kg / t 钢 , total 66kg / t钢 )Reduced by 10.3kg / t 钢 The chemical composition of the molten steel after deoxidation and alloying is: C 0.24%, Si 0.45%, Mn 1.41%, P 0.033%, S 0.021%, V 0.017%, and the rest is Fe and unavoidable inclusions. The P content of the finished product is 0.033wt%, which is 0.010% higher than the final P content of 0.023wt%, that is, the phosphorus recovery during the steelmaking process is 0.010%. Compared with the original slag making process (lime + light-burned dolomite + ore): the FeO of the converter final slag is reduced from 19% to 15.3%, a decrease of 3.7%, and the metal loss is reduced by about 3kg / t 钢 The phosphorus regeneration during the steel-making process was reduced from 0.017% to 0.010%, and the phosphorus regeneration of molten steel was reduced by 0.007%, further ensuring product quality.

Claims

1. An efficient dephosphorization slag agent for converter smelting of medium-high phosphorus molten iron, characterized in that: The dephosphorizing slag agent is composed of barium carbonate ore, blast furnace carbon-containing dust ash, bauxite and a binder, wherein the mass percentages of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite are 45-50%, 30-35% and 20-25% respectively, and the binder is 1.5-2.0% of the weight of barium carbonate ore, blast furnace carbon-containing dust ash and bauxite.

2. The high-efficiency dephosphorization slag-removing agent for smelting medium- and high-phosphorus hot metal in a converter according to claim 1, characterized in that: The chemical composition of the dephosphorizing slag agent is as follows by weight percentage: BaCO3 21.5-27.0wt%, CaCO3 19.0-24.0wt%, A12O3 9.0-13.0wt%, SiO2 9.0-14.0wt%, TFe 8.5-10.0wt%, C 4.5-6.0wt%, and the rest are unavoidable inclusions.

3. The high-efficiency dephosphorization slag-removing agent for smelting medium- and high-phosphorus hot metal in a converter according to claim 1, characterized in that: The chemical composition of the barium carbonate ore is as follows: BaCO3 45.0-53.0wt%, CaCO3 40.0-48.0wt%, and the rest are inevitable inclusions.

4. The high-efficiency dephosphorization slag agent for smelting medium-high phosphorus hot metal in converter according to claim 1, characterized in that: The chemical composition of the carbon-containing dust ash from the blast furnace is as follows: C 14.3-17.2wt%, MgO 2.0-2.5wt%, SiO2 5.5-6.5wt%, TFe 31.0-34.5wt%, Pb 0.7-0.9wt%, Zn 6.8-8.0wt%, and the rest are unavoidable inclusions.

5. The high-efficiency dephosphorization slag agent for smelting medium-high phosphorus hot metal in converter according to claim 1, characterized in that: The chemical composition of the bauxite is as follows: A12O3 50.0-60.0wt%, SiO2 20.0-30.0wt%, and the rest are inevitable inclusions.

6. The high-efficiency dephosphorization slag-removing agent for smelting medium- and high-phosphorus hot metal in a converter according to claim 1, characterized in that: The adhesive is bentonite or water glass.

7. The method for preparing the efficient dephosphorization slag-removing agent for smelting medium-high phosphorus hot metal in converter according to claim 1, characterized in that: The barium carbonate ore, blast furnace carbon dust and bauxite are rolled into raw materials of ≤3mm and then mixed, and bentonite adhesive is added to bond them, and a ball making machine is used to make mixed balls of 10-30mm, and the mixed balls are obtained after air drying.

8. A method for smelting medium-high phosphorus hot metal in a converter based on the efficient dephosphorization slag-removing agent according to claim 1, characterized in that: To do this, follow these steps: 1) Adding medium-high phosphorus molten iron and scrap steel in a mass ratio of 82-85:15-18 into the converter, wherein the molten iron temperature is 1280-1400℃; 2) After opening the oxygen, lower the oxygen lance to 2.0m on the scale plate, open the oxygen valve and start the ignition operation. Adjust the oxygen pressure to 0.85MPa; when blowing oxygen for 1.0min, lower the oxygen lance to 1.2m and add 12-20kg / t of lime. 钢 , Lightly burned dolomite 8-15kg / t 钢 、The dephosphorization slag agent is 8-10kg / t 钢 ; Add 5-8kg / t of lime during blowing for 6-9 minutes 钢 , Lightly burned dolomite 2-5kg / t 钢 , Dephosphorizing slag agent 2-3kg / t 钢 ; Maintain a constant oxygen pressure of 0.85MPa and a constant oxygen lance of 1.2m for blowing for 11-12 minutes, then lower the oxygen lance to a minimum of 1.0m and blow for 1 minute, then turn off the oxygen and stop blowing, measure temperature, and perform sampling and analysis; 3) The smelting end point temperature is controlled at 1645-1655℃, and after the end point P≤0.030wt%, add 1.6-2.4kg / t of raw dolomite 钢 After the steel is discharged.

9. The method for smelting medium-high phosphorus molten iron in a converter according to claim 8, characterized in that: In step 1), the chemical composition of the molten iron is: C 3.5-4.4wt%, Si 0.05-0.50wt%, Mn 0.15-0.40wt%, P 0.200-0.400wt%, S≤0.050wt%, and the rest is Fe and unavoidable inclusions; The chemical composition of the scrap steel is: C 0.17-0.25wt%, Si 0.25-0.45wt%, Mn 0.70-1.30wt%, P≤0.045wt%, S≤0.040wt%, and the rest is Fe and unavoidable inclusions.

10. The method for smelting medium-high phosphorus molten iron in a converter according to claim 8, characterized in that: In step 3), the chemical composition of the raw dolomite is: CaO 30.0-38.0wt%, MgO 19.0-29.0wt%, SiO2≤5.0wt%, and the rest is burnt and unavoidable inclusions.