A converter smelting method using steel scrap refractory and blast furnace dust as slag-making materials

Abstract

The invention discloses a converter smelting method using steel scrap refractory materials and blast furnace dust as slag-making materials. The method is to clean the residual steel in the lining bricks removed during the converter lining replacement, the waste refractory materials removed during the working layer replacement of the continuous casting tundish, and the refractory bricks replaced at the ladle slag line by using an electromagnetic disk, and then roll them into raw materials with a particle size of ≤3 mm by using a ball mill. After that, the raw materials are mixed in the ratio of lining bricks: tundish refractory materials: ladle slag line bricks = 1:2:1 to obtain a mixture. Then, the mixture and blast furnace dry dust are mixed in a certain ratio and added with bentonite binder to be bonded into spheres with a size of 10-30 mm to obtain uniformly mixed spheres. Among them, the mass ratio of each material in the uniformly mixed spheres is: mixture 70-73%, blast furnace dry dust 26-29%, and bentonite binder 1-2%. The method of the invention can recycle the MgO-containing waste refractory materials and blast furnace dry dust, reduce environmental pollution and improve the comprehensive utilization rate of resources.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical solid waste recycling, and particularly relates to a converter smelting method using steel scrap refractories and blast furnace dust as slag-making materials. Background Art

[0002] At present, the lining bricks for converters in steel mills, the casting materials for the working layer of continuous casting tundishes, and the bricks for the slag line of ladles are mainly magnesia refractories. Most of these refractories are treated and discharged together with steel slag after use. At the same time, although the dry dust removed from the blast furnace contains relatively high contents of C and Fe, due to the relatively high contents of Pb and Zn, it is easy to be enriched when recycled to the blast furnace, which affects the smooth operation of the blast furnace production. Therefore, the recycling rate in steel mills is relatively low. The treatment methods of most steel mills are that part of it is used for sintering pellets, part is sold at a low price, and part is left idle. The utilization efficiency of the dust removed from the blast furnace is low and the environmental pollution is large. Summary of the Invention

[0003] The purpose of the present invention is to provide a converter smelting method using steel scrap refractories and blast furnace dust as slag-making materials.

[0004] The purpose of the present invention is achieved as follows. A converter smelting method using steel scrap refractories and blast furnace dust as slag-making materials is realized according to the following steps:

[0005] 1) For the lining bricks removed when changing the lining of the converter, the waste refractories removed when replacing the working layer of the continuous casting tundish, and the refractory bricks replaced at the slag line of the ladle, use an electromagnetic disk to clean the residual steel inside, and use a ball mill to roll them into raw materials with a particle size ≤ 3 mm, and then mix them according to the ratio of lining bricks: tundish refractories: ladle slag line bricks = 1:2:1 to obtain a mixture;

[0006] 2) Mix the mixture with the dry dust removed from the blast furnace in a certain proportion, and then add bentonite binder to bond it into spheres with a diameter of 10 - 30 mm to obtain a mixed sphere;

[0007] Among them, the mass ratio of each material in the mixed sphere is: mixture 70 - 73%, dry dust removed from the blast furnace 26 - 29%, bentonite binder 1 - 2%;

[0008] 3) During the converter smelting process, smelt by replacing the original addition amount of light burned dolomite at a ratio of 1.5 - 2.0:1 for the mixed sphere:

[0009] In the early stage of converter smelting: during 0 - 300 s of oxygen supply, after opening the oxygen, lower the oxygen lance to 2.0 - 2.5 m of the scale plate and then open the oxygen valve for ignition operation. Adjust the oxygen pressure to 0.80 - 0.85 MPa. After successful ignition, adjust the oxygen lance to 1.0 - 1.3 m, and then add 10 - 13 kg / t of lime 钢水 and 5 - 10 kg / t of light burned dolomite钢水 , Mix 2 - 3 kg / t of homogenized pellets 钢水 ;

[0010] During the middle stage of converter smelting: During the oxygen supply time of 300 - 660 s, the oxygen pressure is 0.80 - 0.85 MPa, the lance is controlled at 1.1 - 1.4 m, and add 10 - 12 kg / t of lime 钢水 , 3 - 4 kg / t of calcined dolomite 钢水 , 1 - 2 kg / t of homogenized pellets 钢水 ;

[0011] During the later stage of converter smelting: During the oxygen supply time of 660 - 840 s, the oxygen pressure is 0.85 - 0.92 MPa, the lance is controlled at 0.8 - 1.1 m, and only add 1 - 2 kg / t 钢水 of homogenized pellets;

[0012] The converter blowing end is controlled with the end temperature at 1640 - 1655 °C and the end C content at 0.04 wt% - 0.08 wt%.

[0013] During the converter steelmaking process, to improve the lining life, a large amount of calcined dolomite is added to participate in slag formation to supplement the MgO required by the converter. Combining the characteristics of converter smelting, this invention collects waste magnesia refractories and mixes them with blast furnace dry dust to make pellets and return them to steelmaking to replace part of the slag - forming materials containing MgO. First, it can achieve the purpose of reducing the slag - making cost of converter smelting. Second, it turns waste refractory materials into something useful. Third, it recovers C and metallic Fe in blast furnace dry dust, provides heat for converter smelting, improves the technical and economic indicators of converter smelting. Fourth, it improves the utilization efficiency of blast furnace dust and reduces the environmental pollution problems brought thereby.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. The method of this invention can recycle waste MgO - containing refractories and blast furnace dry dust, reduce environmental pollution, and improve the comprehensive utilization rate of resources;

[0016] 2. The addition amount of calcined dolomite during the converter smelting process of this invention is 9 - 13 kg / t less than that of the prior art 钢水 , reducing the steel - making slag - making cost by 2.84 - 4.10 yuan / t 钢水 ;

[0017] 3. Under the conditions of heat supplement from C in blast furnace dust and reduction of the total amount of converter slag materials added, this invention's method creates conditions for the reduction of iron oxides in the converter, reducing the TFe content in the converter final slag by 1.0 wt% - 1.5 wt%, and reducing the metal loss cost by 3.0 - 4.5 yuan / t 钢水 ;

[0018] 4. The method of this invention is simple and reliable, and is easy to promote and apply. Detailed implementation manners

[0019] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited in any way. Any transformation or replacement based on the teachings of the present invention falls within the protection scope of the present invention.

[0020] A converter smelting method using steel waste refractories and blast furnace dust as slag-making materials of the present invention is realized according to the following steps:

[0021] 1) For the refractory bricks removed during the converter lining replacement and relining, the waste refractories removed during the replacement of the working layer of the continuous casting tundish, and the refractory bricks replaced at the slag line of the ladle, use an electromagnetic disk to clean the residual steel inside, and use a ball mill to crush them into raw materials with a particle size ≤ 3 mm, and then mix them according to the ratio of refractory bricks of the converter lining: tundish refractories: ladle slag line bricks = 1:2:1 to obtain a mixture;

[0022] 2) Mix the mixture with blast furnace dry dust in a certain proportion, and then add bentonite binder to bond it into spheres with a diameter of 10 - 30 mm to obtain uniformly mixed spheres;

[0023] Among them, the mass ratio of each material in the uniformly mixed spheres is: mixture 70 - 73%, blast furnace dry dust 26 - 29%, bentonite binder 1 - 2%;

[0024] 3) During the converter smelting process, smelt by replacing the original addition amount of light burned dolomite at a ratio of 1.5 - 2.0:1 for the uniformly mixed spheres:

[0025] In the early stage of converter smelting: during the oxygen supply of 0 - 300 s, after opening the oxygen, lower the oxygen lance to 2.0 - 2.5 m of the scale plate and then open the oxygen valve for ignition operation. Adjust the oxygen pressure to 0.80 - 0.85 MPa. After successful ignition, adjust the oxygen lance to 1.0 - 1.3 m, and then add 10 - 13 kg / t of lime 钢水 、5 - 10 kg / t of light burned dolomite 钢水 ,and 2 - 3 kg / t of uniformly mixed spheres 钢水 ;

[0026] In the middle stage of converter smelting: during the oxygen supply of 300 - 660 s, the oxygen pressure is 0.80 - 0.85 MPa, the oxygen lance is controlled at 1.1 - 1.4 m, and add 10 - 12 kg / t of lime 钢水 、3 - 4 kg / t of light burned dolomite 钢水 ,and 1 - 2 kg / t of uniformly mixed spheres 钢水 ;

[0027] In the late stage of converter smelting: during the oxygen supply of 660 - 840 s, the oxygen pressure is 0.85 - 0.92 MPa, the oxygen lance is controlled at 0.8 - 1.1 m, and only add 1 - 2 kg / t 钢水 of uniformly mixed spheres;

[0028] The end-point control of converter blowing has an end-point temperature of 1640 - 1655 °C and an end-point C content of 0.04 wt% - 0.08 wt%.

[0029] In step 3, if the end-point C < 0.04 wt%, 0.5 - 1.0 kg / t of the above-mentioned blended balls are added to the furnace before tapping the converter. 钢水 。

[0030] The chemical composition of the furnace lining bricks is by weight percentage: C 16.5 wt% - 18.0 wt%, MgO 73.0 wt% - 76.0 wt%, SiO2 2.5 wt% - 3.5 wt%, Al2O3 2.7 wt% - 3.8 wt%, and the rest are inevitable inclusions.

[0031] The chemical composition of the waste refractories is by weight percentage: MgO 75.0 wt% - 77.5 wt%, SiO2 7.3 wt% - 8.5 wt%, Al2O3 7.0 wt% - 8.5 wt%, and the rest are inevitable inclusions;

[0032] The chemical composition of the ladle slag line bricks is by weight percentage: C 19.0 wt% - 23.0 wt%, MgO 69.6 wt% - 72.6 wt%, SiO2 2.2 wt% - 3.0 wt%, Al2O3 5.0 wt% - 6.0 wt%, and the rest are inevitable inclusions.

[0033] The chemical composition of the blast furnace dry dust is by weight percentage: C 14.3 wt% - 17.2 wt%, MgO 2.0 wt% - 2.5 wt%, SiO2 5.5 wt% - 6.5 wt%, TFe 31.0 wt% - 34.5 wt%, Pb 0.7 wt% - 0.9 wt%, Zn 6.8 wt% - 8.0 wt%, and the rest are inevitable inclusions.

[0034] The chemical composition of the blended balls contains by weight percentage: MgO 50 wt% - 60 wt% and C 10 wt% - 20 wt%.

[0035] Example 1

[0036] 1) During the removal of the converter lining, clean the residual steel in the removed lining bricks, the waste refractories removed during the replacement of the working layer of the continuous casting tundish, and the refractory bricks replaced at the ladle slag line using an electromagnetic disk, and then use a ball mill to crush them into raw materials with a particle size of ≤3 mm. The chemical composition of the lining bricks is 17.2 wt% C, 73.8 wt% MgO, 2.7 wt% SiO2, 3.1 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the waste refractories is 76.2 wt% MgO, 7.7 wt% SiO2, 7.3 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the ladle slag line bricks is 19.8 wt% C, 70.7 wt% MgO, 2.6 wt% SiO2, 5.22 wt% Al2O3, and the rest are inevitable inclusions.

[0037] 2) Mix the lining bricks, waste refractories, and ladle slag line bricks obtained in step 1) in a ratio of 1:2:1 and then roll them into a mixture with a particle size of ≤3 mm. Mix the mixture, blast furnace dry dust, and bentonite in a ratio of 72%, 26%, and 2% to make a uniformly mixed ball with a size of 10 - 30 mm. The chemical composition of the blast furnace dry dust is 15.4 wt% C, 2.3 wt% MgO, 5.8 wt% SiO2, 31.7 wt% TFe, 0.8 wt% Pb, 7.2 wt% Zn, and the rest are inevitable inclusions; the chemical composition of the uniformly mixed ball is 10.8 wt% C, 54.8 wt% MgO, 5.3 wt% SiO2, 8.2 wt% TFe, 0.2 wt% Pb, 1.9 wt% Zn.

[0038] 3) During the converter smelting process, add the uniformly mixed balls made in step 2) to replace the original light burned dolomite in a ratio of 1.5:1.

[0039] The converter smelting process is divided into three stages according to the oxygen supply time: the early stage (0, 300] S, the middle stage (300, 660] S, and the late stage (660, 840] S. The addition amount of the uniformly mixed balls is 5 - 8 kg / t 钢水 , the converter oxygen supply pressure is 0.80 - 0.92 MPa, and the oxygen lance position is controlled at 0.8 - 1.4 m;

[0040] Converter smelting early stage control mode: After opening the oxygen, lower the oxygen lance to 2.5 m on the scale plate and then open the oxygen valve for ignition operation. The oxygen pressure is 0.82 MPa. After successful ignition, adjust the oxygen lance to 1.3 m, and then add 11 kg / t of lime 钢水 , 7 kg / t of light burned dolomite 钢水 , and 3 kg / t of the uniformly mixed balls 钢水 .

[0041] Converter smelting mid-term control mode: oxygen pressure 0.83 MPa, lance control 1.1 m, lime addition 10 kg / t 钢水 and light burned dolomite 3 kg / t 钢水 , homogenized pellets 1 kg / t 钢水 .

[0042] Converter smelting late-stage control mode: oxygen pressure 0.90 MPa, lance control 0.8 m, lime addition 0 kg / t 钢水 and light burned dolomite 0 kg / t 钢水 , homogenized pellets 2 kg / t 钢水 .

[0043] Converter blowing end-point control situation: end-point temperature 1647 °C, end-point C 0.06 wt%, TFe content in the converter final slag is 17.5%.

[0044] Example 2

[0045] 1) Clean the residual steel in the three materials of the lining bricks removed when changing the converter lining, the waste refractories removed from the working layer of the continuous casting tundish, and the refractory bricks replaced at the ladle slag line using an electromagnetic disk, and then roll them into raw materials with a particle size ≤ 3 mm using a ball mill. The chemical composition of the lining bricks is 17.9 wt% C, 75.1 wt% MgO, 2.7 wt% SiO2, 2.8 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the waste refractories is 75.4 wt% MgO, 7.4 wt% SiO2, 7.6 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the ladle slag line bricks is 21.4 wt% C, 71.3 wt% MgO, 2.6 wt% SiO2, 5.4 wt% Al2O3, and the rest are inevitable inclusions.

[0046] 2) Mix the lining bricks, waste refractories, and ladle slag line bricks obtained in step 1) in a ratio of 1:2:1 and roll them into a mixture ≤ 3 mm. Mix the mixture, blast furnace dry dust, and bentonite in a ratio of 73%, 26%, and 1% to make 10 - 30 mm homogenized pellets. The chemical composition of the blast furnace dry dust is 16.2 wt% C, 2.2 wt% MgO, 6.1 wt% SiO2, 32.8 wt% TFe, 0.8 wt% Pb, 7.6 wt% Zn, and the rest are inevitable inclusions; the chemical composition of the homogenized pellets is 11.4 wt% C, 54.8 wt% MgO, 5.3 wt% SiO2, 8.5 wt% TFe, 0.2 wt% Pb, and 2.0 wt% Zn.

[0047] 3) During the converter smelting process, the mixed balls are used to replace the original addition amount of light burned dolomite at a ratio of 1.5:1 for smelting.

[0048] Converter smelting early-stage control mode: After blowing oxygen, lower the oxygen lance to 2.3 m on the scale plate and then open the oxygen valve for ignition operation. The oxygen pressure is 0.83 MPa. After successful ignition, adjust the oxygen lance to 1.1 m, and then add 13 kg / t of lime 钢水 , 9 kg / t of light burned dolomite 钢水 , 3 kg / t of mixed balls 钢水 .

[0049] Converter smelting mid-stage control mode: The oxygen pressure is 0.83 MPa, the oxygen lance is controlled at 1.3 m, and 10 kg / t of lime is added 钢水 , 3 kg / t of light burned dolomite 钢水 , 2 kg / t of mixed balls 钢水 .

[0050] Converter smelting late-stage control mode: The oxygen pressure is 0.88 MPa, the oxygen lance is controlled at 0.9 m, and the lime addition amount is 0 kg / t 钢水 , 0 kg / t of light burned dolomite 钢水 , 1 kg / t of mixed balls 钢水 .

[0051] Converter blowing end-point control situation: The end-point temperature is 1647 °C, the end-point C is 0.03 wt%, and 1 kg / t of mixed balls is added into the furnace before tapping from the converter 钢水 , and the TFe content of the converter final slag is 17.8%.

[0052] Example 3

[0053] 1) When disassembling the furnace lining of the converter for furnace lining replacement, the waste refractories removed from the working layer replacement of the continuous casting tundish, and the refractory bricks replaced at the ladle slag line are cleaned of the residual steel inside using an electromagnetic disk, and then rolled into raw materials with a size of ≤3 mm using a ball mill. The chemical composition of the furnace lining brick is 17.3 wt% C, 74.7 wt% MgO, 2.5 wt% SiO2, 3.2 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the waste refractory is 76.8 wt% MgO, 7.7 wt% SiO2, 7.3 wt% Al2O3, and the rest are inevitable inclusions; the chemical composition of the ladle slag line brick is 22.1 wt% C, 72.2 wt% MgO, 2.5 wt% SiO2, 5.3 wt% Al2O3, and the rest are inevitable inclusions.

[0054] 2) Mix the ladle lining bricks, waste refractories, and ladle slag line bricks obtained in step 1) in a ratio of 1:2:1, then roll them into a mixture with a particle size ≤ 3 mm. Next, mix the mixture, blast furnace dry dust, and bentonite in a ratio of 70%, 29%, and 1% respectively to make a uniformly mixed ball with a size of 10 - 30 mm. The chemical composition of the blast furnace dry dust by weight percentage is C 15.6 wt%, MgO 2.4 wt%, SiO₂ 5.8 wt%, TFe 33.9 wt%, Pb 0.7 wt%, Zn 7.7 wt%, and the rest are inevitable inclusions; the chemical composition of the uniformly mixed ball by weight percentage is C 11.4 wt%, MgO 53.3 wt%, SiO₂ 5.3 wt%, TFe 9.8 wt%, Pb 0.2 wt%, Zn 2.2 wt%.

[0055] 3) During the converter smelting process, add the uniformly mixed balls to replace the original light burned dolomite in a ratio of 2:1 for smelting.

[0056] Converter smelting early-stage control mode: After opening the oxygen, lower the oxygen lance to 2.1 m on the scale plate and then open the oxygen valve for ignition operation. The oxygen pressure is 0.85 MPa. After successful ignition, adjust the oxygen lance to 1.4 m, and then add 13 kg / t of lime 钢水 , 7 kg / t of light burned dolomite 钢水 , and 3 kg / t of uniformly mixed balls.

[0057] Converter smelting mid-stage control mode: The oxygen pressure is 0.85 MPa, control the oxygen lance at 1.2 m, add 11 kg / t of lime 钢水 , 2 kg / t of light burned dolomite 钢水 , and 2 kg / t of uniformly mixed balls 钢水 .

[0058] Converter smelting late-stage control mode: The oxygen pressure is 0.90 MPa, control the oxygen lance at 0.8 m, and the lime addition amount is 0 kg / t 钢水 , 0 kg / t of light burned dolomite 钢水 , and 2 kg / t of uniformly mixed balls 钢水 .

[0059] Converter blowing end-point control situation: The end-point temperature is 1653 °C, the end-point C is 0.06 wt%, and the TFe content in the converter final slag is 17.1%.

Claims

1. A converter smelting method using steel scrap refractory and blast furnace dust as slag-making materials, characterized in that, It is implemented according to the following steps: 1) When disassembling the converter lining during converter relining, the lining bricks removed, the waste refractories removed from the working layer replacement of the continuous casting tundish, and the refractory bricks replaced at the ladle slag line are cleaned of the residual steel inside using an electromagnetic disk, and then crushed into raw materials with a particle size ≤ 3 mm using a ball mill and mixed in a ratio of lining brick: tundish refractory: ladle slag line brick = 1:2:1 to obtain a mixture; 2) The mixture is mixed with blast furnace dry dust removal ash in a certain ratio and then added with bentonite binder to bond into spheres with a size of 10 - 30 mm to obtain uniformly mixed spheres; Among them, the mass ratio of each material in the uniformly mixed spheres is: mixture 70 - 73%, blast furnace dry dust removal ash 26 - 29%, bentonite binder 1 - 2%; 3) During the converter smelting process, the uniformly mixed spheres are used to replace the light burned dolomite and added for smelting in a ratio of light burned dolomite: uniformly mixed spheres = 1.5 - 2.0:1; Early stage of converter smelting: During the period of oxygen supply from 0 to 300 s (excluding 0 s), after opening the oxygen, lower the oxygen lance to 2.0 - 2.5 m of the scale plate and then open the oxygen valve for ignition operation. Adjust the oxygen pressure to 0.80 - 0.85 MPa. After successful ignition, adjust the oxygen lance to 1.0 - 1.3 m, and then add 10 - 13 kg / t of lime 钢水 , 5 - 10 kg / t of lightly burned dolomite 钢水 , 2 - 3 kg / t of blended pellets 钢水 ; During the middle stage of converter smelting: oxygen supply is carried out for 300 - 660 s (excluding 300 s), oxygen pressure is 0.80 - 0.85 MPa, the oxygen lance is controlled at 1.1 - 1.4 m, and 10 - 12 kg / t of lime is added 钢水 , 3 - 4 kg / t of lightly burned dolomite 钢水 , 1 - 2 kg / t of blended pellets 钢水 ; During the later stage of converter smelting: within 660 - 840 s of oxygen supply (excluding 660 s), oxygen pressure 0.85 - 0.92 MPa, oxygen lance controlled at 0.8 - 1.1 m, only adding 1 - 2 kg / t 钢水 Mixing ball; The end point temperature of the converter blowing is controlled at 1640 - 1655 °C, and the end point C content is 0.04 wt% - 0.08 wt%.

2. The converter smelting method according to claim 1, wherein In step 3, if the end point C < 0.04 wt%, add 0.5 - 1.0 kg / t of the blended balls into the converter before tapping 钢水 .

3. The converter smelting method according to claim 1, characterized in that, The chemical composition of the lining bricks is by weight percentage: C 16.5 wt% - 18.0 wt%, MgO 73.0 wt% - 76.0 wt%, SiO2 2.5 wt% - 3.5 wt%, Al2O3 2.7 wt% - 3.8 wt%, and the rest are inevitable inclusions.

4. The converter smelting method according to claim 1, characterized in that, The chemical composition of the waste refractories is by weight percentage: MgO 75.0 wt% - 77.5 wt%, SiO2 7.3 wt% - 8.5 wt%, Al2O3 7.0 wt% - 8.5 wt%, and the rest are inevitable inclusions.

5. The converter smelting method according to claim 1, characterized in that, The chemical composition of the ladle slag line bricks is by weight percentage: C 19.0 wt% - 23.0 wt%, MgO 69.6 wt% - 72.6 wt%, SiO2 2.2 wt% - 3.0 wt%, Al2O3 5.0 wt% - 6.0 wt%, and the rest are inevitable inclusions.

6. The converter smelting method according to claim 1, characterized in that, The chemical composition of the blast furnace dry dust removal ash is by weight percentage: C 14.3 wt% - 17.2 wt%, MgO 2.0 wt% - 2.5 wt%, SiO2 5.5 wt% - 6.5 wt%, TFe 31.0 wt% - 34.5 wt%, Pb 0.7 wt% - 0.9 wt%, Zn 6.8 wt% - 8.0 wt%, and the rest are inevitable inclusions.