Stable, smooth and low-fuel-consumption blast furnace smelting method under low-grade and high-zinc condition

Abstract

The invention provides a stable, smooth and low-fuel-consumption blast furnace smelting method under low-grade and high-zinc conditions. The method is characterized by comprising the following steps: 1) feeding the following crude fuels into a blast furnace: 45-49 t / batch of ore and 9-12 t / batch of coke; (2) blast furnace smelting is conducted on the raw fuel entering the furnace in the step (1) under the following conditions that the cold air flow is 3800-4500 m / min, the air speed is 210-250 m / s, the cold air pressure is larger than 350 KPa, the air temperature is larger than 1150 DEG C, the oxygen enrichment is 13,000-15,000 m / h, the furnace top pressure is 170-190 KPa, the furnace top temperature is 135-149 DEG C, and the physical heat of molten iron is 1460-1490 DEG C; 3, qualified molten iron is obtained.By means of blast furnace smelting in the step 2, the smelting problem caused by low in-furnace grade and large zinc load is solved, the blast furnace condition is stable and smooth for a long time, fuel consumption is reduced, technical and economic indexes are improved, resource channels are widened, and the blast furnace ore using cost is reduced.

Description

Technical Field

[0001] The invention relates to a blast furnace smelting method, in particular to a blast furnace smelting method with stable forward movement and low fuel consumption under low-grade and high-zinc conditions, belonging to the technical field of blast furnace smelting. Background Art

[0002] With the year-on-year reduction of iron ore resources, the ore raw materials of steel enterprises have changed from the original single-variety ore to the current multi-variety ore. In addition to using local ore, sintered ore and pelletized ore, some imported ore is also used, resulting in low ore grade and zinc content as high as 0.316%, causing the alkali metal load entering the furnace to be as high as 0.65kg / t, which is 4 times the national standard, and aggravating the load of harmful elements such as sulfur, alkali, lead, zinc, and titanium in the raw materials entering the furnace. Not only that, in order to meet the needs of iron ore smelting, the coal and ore blending structure are frequently adjusted, which not only increases the difficulty of blast furnace operation, but also leads to a decrease in the stability of blast furnace conditions, deterioration of technical and economic indicators, and increased fuel consumption.

[0003] In recent years, with the popularization of the awareness of the hazards of zinc enrichment, the control of zinc load in blast furnaces has made great progress. Maintaining low zinc load smelting is an important technical means to ensure the stability, smooth operation and longevity of blast furnaces, optimize technical and economic indicators, and reduce fuel ratios. The zinc load in blast furnace smelting refers to the sum of the zinc content brought into the furnace by all materials such as sintered ore, pelletized ore, lump ore, coke, and pulverized coal injection, and the mass ratio contained in each ton of molten iron, expressed as kg / t.Fe.

[0004] The circulation and enrichment of zinc in the blast furnace will lead to unstable blast furnace airflow, increase the frequency of abnormal furnace conditions such as collapse, pipeline, and hanging materials. Zinc will be converted into zinc vapor as it descends with the charge in the blast furnace. After condensation and accumulation inside the blast furnace, zinc vapor will be deposited on the surface of the furnace lining, making the furnace wall thicker and even forming furnace tumors, deteriorating the gas passage, reducing the gas concentration and utilization rate, and affecting the permeability of the charge column. In addition, zinc vapor will react chemically with coke, enhancing the gasification reaction ability of coke and reducing the strength after the reaction. In addition, the high alkali metal load catalyzes the coke, resulting in an increase in fuel ratio and production costs, making the enterprise lose its competitiveness, and at the same time, it is not conducive to the comprehensive utilization of iron ore resources.

[0005] Therefore, it is necessary to improve existing technologies and make the best use of existing iron ore and fuel resources. Summary of the invention

[0006] In order to ensure stable and smooth blast furnace conditions, low fuel consumption and low cost under the conditions of low ore grade, high zinc load, high load of harmful elements such as alkali load and lead load, and large fluctuation in fuel quality, and to improve the removal rate of harmful elements such as zinc and alkali metals, the present invention provides a blast furnace smelting method with stable, smooth operation and low fuel consumption under the conditions of low grade and high zinc ore.

[0007] The present invention provides a blast furnace smelting method with stable forward operation and low fuel consumption under low-grade and high-zinc conditions, comprising the following steps: 1) The following raw materials are fed into a blast furnace with a furnace capacity of 2500m³: Ore 45-49 t / batch Coke 9-12 t / batch The ore is: 70-72% sintered ore + 28%-30% pelletized ore, the sum of the two is 100%, the drum strength of the sintered ore is greater than 80%, and the low temperature reduction powder index RDI+3.15mm is greater than 60%; Control the ore grade to 56.3-56.8%, zinc load to 0.40-0.7kg / t, total potassium and sodium load to 4.0-6.5kg / t, coke reaction intensity to >67%, coke ratio to 350-380kg / t; At the same time, pulverized coal is sprayed into the blast furnace at a rate of 40 t / h, and the coal injection ratio is controlled at 135-150 kg / t; 2) The raw materials and fuels in step 1) are subjected to blast furnace smelting under the following conditions: Cold air flow rate 3800-4500m³ / min, Wind speed 210-250 m / s, Cold air pressure>350KPa, Air temperature>1150℃, Oxygen enrichment 13000-15000m³ / h, Furnace top pressure 170-190 KPa, The furnace top temperature is 135-149℃, The physical heat of molten iron is 1460-1490℃. 3) Through blast furnace smelting in step 2), obtain: Molten iron of the following chemical composition: Si: 0.2-0.4%, Mn: 0.1-0.2%, P: 0.07-0.08%, S: 0.01-0.06%, Ti: 0.1-0.3%, Cu: 0.01-0.03%, As: 0.004-0.009%; Slag of the following chemical composition: SiO 2 32-34%, CaO: 38-40%, Al 2 O 3 : 10.5-12%, MgO: 8-9.5%, MnO: 0.1-0.4%, FeO: 0.2-0.7%, S: 0.6-1.2%, K 2 O: 0.3-0.7 %, Na 2 O: 0.5-1.0%, TiO2 :1.5-3.5 %, basicity (CaO / SiO 2 ):1.15-1.2; Gas of the following composition: CO:17-23%,CO 2 :15-25%,H 2 :0,01-2%, CO 2 / (CO 2 +CO) >47; And the following indicators: Slag iron ratio: 380-390kg / t, gray iron ratio: 18-22 kg / t, fuel ratio <520 kg / t, permeability index >22000 Q / ΔP.

[0008] The raw fuel in step 1) is fed into the blast furnace after conventional distribution.

[0009] The blast furnace smelting in step 2) is conventional smelting.

[0010] Compared with the prior art, the present invention has the following advantages and significant technical effects: the present invention breaks the inherent low-grade, high-zinc load smelting, poor blast furnace stability, and high fuel consumption operation mode of blast furnace smelting, and targets blast furnaces with a comprehensive inlet grade lower than 56.5%, a slag ratio greater than 380kg / t, a zinc load greater than 0.5kg / t, and large fluctuations in the quality of raw materials and fuels. By adjusting the ore distribution structure, adjusting the initial coal gas flow distribution and appropriately developing the central gas flow, improving the slag fluidity, improving the slag air and liquid permeability, controlling the appropriate furnace stability, and controlling the cooling intensity, the edge accumulation or furnace wall can be avoided. The thickening of the structure and the improvement of the exclusion rate of harmful elements, especially zinc, ensured the long-term stable and smooth operation of the blast furnace condition, reduced fuel consumption, and greatly improved various technical and economic indicators. The output increased from 6,300 tons / day to 6,700 tons / day, the fuel ratio decreased from 520kg / t to 511kg / t, and the coke ratio decreased from 380kg / t to 370kg / t. The quality of molten iron was not only improved, but the silicon and sulfur double standards increased from 87% to 95%, the molten iron qualification rate was 100%, and the iron cost achieved the monthly budget indicators and cost reduction targets, expanded the resource procurement channels, and reduced the ore cost by 30 yuan / ton. DETAILED DESCRIPTION

[0011] The present invention will be further described below by way of examples. Example 1

[0012] The method for smelting a blast furnace with stable forward operation and low fuel consumption under low-grade and high-zinc conditions comprises the following steps: 1) The following raw materials are fed into a blast furnace with a capacity of 2500m³ according to conventional distribution: Ore 48 t / batch Coke 10.7 t / batch The ore is: 72% sintered ore + 28% pelletized ore, the sintered ore drum strength is > 80%, and the low temperature reduction powder index RDI+3.15mm is > 60%; Controlled ore grade of 56.4%, zinc load of 0.58kg / t, total potassium and sodium load of 5.0kg / t, coke reaction intensity>67%, coke ratio of 375.41kg / t; At the same time, pulverized coal is sprayed into the blast furnace at a rate of 40 t / h, and the coal injection ratio is controlled at 140.61 kg / t; 2) The raw materials and fuels in step 1) are subjected to conventional blast furnace smelting under the following conditions: Cold air flow rate 4271m³ / min, Wind speed 246 m / s, Cold air pressure 376.39KPa, Wind temperature 1182℃, Oxygen enrichment 14038m³ / h, Furnace top pressure 184.55 KPa, The furnace top temperature is 146℃. Physical heat of molten iron 1460℃; 3) Through blast furnace smelting in step 2), obtain: Hot metal with the following chemical composition (%): Si: 0.334%, Mn: 0.157%, P: 0.077%, S: 0.017%, Ti: 0.16%, Cu: 0.014%, As: 0.007%; Slag of the following chemical composition: SiO 2 33.98%, CaO: 39.75%, Al 2 O 3 : 11.51%, MgO: 8.64%, MnO: 0.19%, FeO: 0.51%, S: 1.02%, K 2 O: 0.54%, Na 2 O: 0.67%, TiO 2 : 2.72%, basicity (CaO / SiO 2 ):1.17; Gas of the following composition: CO:21.97%,CO 2 :19.82%,H 2 :1.36%, CO 2 / (CO 2 +CO):47.57; And the following indicators: Slag iron ratio: 380.57 kg / t, gray iron ratio: 20.92 kg / t, fuel ratio 516.01 kg / t, permeability index 22784Q / ΔP. Example 2

[0013] The method for smelting a blast furnace with stable forward operation and low fuel consumption under low-grade and high-zinc conditions comprises the following steps: 1) The following raw materials are fed into a blast furnace with a capacity of 2500m³ according to conventional distribution: Ore 45 t / batch, Coke 11.88t / batch, The ore is: 70% sintered ore + 30% pelletized ore, and the drum strength of the sintered ore is greater than 80%, and the low-temperature reduction powder index of the sintered ore RDI+3.15mm is greater than 60%; Control the ore grade into the furnace to be 56.45%, zinc load to be 0.56kg / t, total potassium and sodium load to be 5.47kg / t, coke strength after reaction to be >67%, and coke ratio to be 369.63kg / t; At the same time, pulverized coal is sprayed into the blast furnace at a rate of 40 t / h, and the coal injection ratio is controlled at 145.20 kg / t; 2) The raw materials and fuels in step 1) are subjected to conventional blast furnace smelting under the following conditions: Cold air flow rate 4145 m³ / min, Wind speed 235 m / s, Cold air pressure 363.95KPa, Air temperature 1208℃, Oxygen enrichment 14153m³ / h, Furnace top pressure 176.80KPa, The furnace top temperature is 144℃. Physical heat of molten iron 1490℃; 3) Through blast furnace smelting in step 2), obtain: Molten iron of the following chemical composition: Si: 0.32%, Mn: 0.14%, P: 0.078%, S: 0.023%, Ti: 0.146%, Cu: 0.012%, As: 0.008%; Slag of the following composition: SiO 2 33.97%, CaO: 39.72%, Al 2 O 3 : 11.48%, MgO: 8.74%, MnO: 0.21%, FeO: 0.56%, S: 1.01%, K 2 O: 0.546%, Na 2O: 0.73%, TiO 2 : 2.73%, basicity (CaO / SiO 2 ):1.16; Gas of the following composition: CO:18.42%,CO 2 :19.42%,H 2 :1.01%, CO 2 / (CO 2 +CO):49.27; And the following indicators: Slag iron ratio: 380.56 kg / t, gray iron ratio: 20.92 kg / t, fuel ratio 514.83 kg / t, permeability index 22924Q / ΔP.

Claims

1. A blast furnace smelting method with stable forward operation and low fuel consumption under low-grade and high-zinc conditions, characterized in that The following steps are involved: 1) The following raw materials are fed into a blast furnace with a furnace capacity of 2500m³: Ore 45-49 t / batch Coke 9-12 t / batch The ore is: 70-72% sintered ore + 28%-30% pelletized ore, the sum of the two is 100%, the drum strength of the sintered ore is greater than 80%, and the low temperature reduction powder index RDI+3.15mm is greater than 60%; Control the ore grade to 56.3-56.8%, zinc load to 0.40-0.7kg / t, total potassium and sodium load to 4.0-6.5kg / t, coke reaction intensity to >67%, coke ratio to 350-380kg / t; At the same time, pulverized coal is sprayed into the blast furnace at a rate of 40 t / h, and the coal injection ratio is controlled at 135-150 kg / t; 2) The raw materials and fuels in step 1) are subjected to blast furnace smelting under the following conditions: Cold air flow rate 3800-4500m³ / min, Wind speed 210-250 m / s, Cold air pressure>350KPa, Air temperature>1150℃, Oxygen enrichment 13000-15000m³ / h, Furnace top pressure 170-190 KPa, The furnace top temperature is 135-149℃, The physical heat of molten iron is 1460-1490℃. 3) Through blast furnace smelting in step 2), obtain: Molten iron of the following chemical composition: Si: 0.2-0.4%, Mn: 0.1-0.2%, P: 0.07-0.08%, S: 0.01-0.06%, Ti: 0.1-0.3%, Cu: 0.01-0.03%, As: 0.004-0.009%; Slag of the following chemical composition: SiO2 32-34%, CaO: 38-40%, Al2O3: 10.5-12%, MgO: 8-9.5%, MnO: 0.1-0.4%, FeO: 0.2-0.7%, S: 0.6-1.2%, K2O: 0.3-0.7%, Na2O: 0.5-1.0 %, TiO2: 1.5-3.5 %, alkalinity (CaO / SiO2): 1.15-1.2; Gas of the following composition: CO: 17-23%, CO2: 15-25%, H2: 0,01-2%, CO2 / (CO2+CO) >47; And the following indicators: Slag iron ratio: 380-390kg / t, gray iron ratio: 18-22 kg / t, fuel ratio <520 kg / t, permeability index >22000Q / ΔP.