Method for blast furnace low fuel ratio smelting under high alkali metal load condition

Abstract

The invention discloses a blast furnace low fuel ratio smelting method under a high alkali metal load condition. According to the method, in the blast furnace smelting operation, the comprehensive charging grade is lower than 57%, the slag amount is larger than 370 kg / t, the zinc load is larger than 0.4 kg / t, the potassium-sodium load is larger than 5.5 kg / t, the titanium load is larger than 13.0 kg / t, the coke reactivity is higher than 25%, the strength after reaction is lower than 67%, the M40 is lower than 87%, the M10 is higher than 6.0%, and the crude fuel quality fluctuation is large, through optimization of a blast furnace heat system, optimization of a slagging system and regular alkali removal operation of the blast furnace; and adjusting balanced development of two gas flows of the blast furnace to solve the problems that alkali metal in the furnace is cyclically enriched, the furnace condition is stable and smooth, and the fuel ratio is increased. By adopting the method, the problems of serious coke catalytic damage, poor furnace condition stability and high fuel ratio in high-harmful-element and low-grade blast furnace operation are greatly improved, the influence of high alkali metal load on stable and smooth furnace condition and fuel consumption is reduced, the furnace condition is stabilized to the maximum extent, the technical and economic indexes are improved, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnace smelting, and in particular relates to a method for blast furnace low fuel ratio smelting under high alkali metal load conditions. Background Art

[0002] Yunnan is known as the Kingdom of Nonferrous Metals. Kunming Iron and Steel is located in Anning City, Yunnan Province, far away from the port. The freight is close to 300 yuan / ton, which is not conducive to the large-scale use of imported iron ore resources. There are few large iron ore deposits around Yunnan. There are small deposits, more poor ores than rich ores, and most of them are associated ores of tin, lead and zinc. They are low-grade and have high content of harmful elements (arsenic, sulfur, lead, zinc content, high burn loss). Kunming Iron and Steel has its own mine with an annual output of 4 million tons of Dahongshan iron ore. In Kunming Iron and Steel's ore structure, the proportion of pipeline refined products in mixed ore is 55%, the proportion of pipeline refined products in pelletized ore is 80%, and the proportion of self-produced pipeline refined products in the total ore structure reaches 60%. The alkali metal content (Na20+K20) in pipeline refined coal reaches 0.40%, which is at a very high level. The alkali metal content (Na20+K20) in 65 refined coal used for pelletizing reaches 0.25%, and the alkali metal content in 62 refined coal used for sintering reaches 0.35%. The caviar powder (Na20+K20) in small mines reaches 0.36%. The coking coal used for coke mainly comes from Guizhou, and the catalytic index alkali metal content is relatively high. The alkali metal content in coke reaches 1.5%, and the blast furnace pulverized coal reaches 2.2%. Except for imported ores, all materials are high-alkali metal materials. The national standard controls the alkali metal load of the blast furnace to be ≤3.0kg / t, while the alkali metal load of Kunming Steel is as high as 5.5kg / t. Kunming Steel uses 70-75% local ore + 25-30% imported ore for sintering ore, and uses a large proportion of local resources with high alkali metal content, which further aggravates the load of harmful elements such as "sulfur, alkali, lead, zinc, and titanium" entering the blast furnace. In addition, the quality of the raw materials entering the factory fluctuates greatly, the blast furnace is difficult to operate, and the furnace condition is poor. Such unfavorable conditions restrict the stability of Kunming Steel's blast furnace condition and the reduction of fuel ratio.

[0003] With the large-scale, modernized, intelligent and high-intensity smelting operation of blast furnaces, the requirements for refined material conditions are getting higher and higher, especially the strict control of alkali metal load. All enterprises are pursuing high-intensity smelting to obtain high output and better technical and economic indicators. High grade, large air volume, high oxygen enrichment, low harmful elements are the main means of high-intensity smelting. Among them, low alkali metal load smelting is a very important technical means to stabilize the furnace condition of the blast furnace, optimize technical and economic indicators and reduce the fuel ratio. The alkali metal load in blast furnace smelting refers to the sum of the contents of Na20 and K20 brought into the furnace by all materials such as ore, coke, and injection coal, and the mass ratio reached in each ton of molten iron, expressed as kg / t.Fe. The high or low alkali metal load during normal blast furnace smelting represents the quality of the incoming materials. Domestic blast furnaces usually adopt low alkali metal load and low harmful element load mode smelting in pursuit of low fuel consumption. Generally, the alkali metal load is controlled at 2.5kg / t or even lower. However, low-alkali metal smelting has higher requirements on the quality of raw materials and fuels, and the proportion of imported ore needs to be increased. In addition, the intensified smelting with low alkali metal load has very high requirements on the ore structure, coal structure and regional location.

[0004] In view of the above problems, the present invention aims to provide a method for blast furnace low fuel ratio smelting under high alkali metal load conditions. Summary of the invention

[0005] The object of the present invention is to provide a method for smelting in a blast furnace with a low fuel ratio under high alkali metal load conditions.

[0006] The first object of the present invention is achieved by following the steps: 1) Control the raw material and fuel conditions to be about 56.6% in the furnace, the slag ratio is greater than 380kg / t, the zinc load is 0.4-0.75kg / t, the potassium and sodium load is 5.5-7kg / t, the titanium load is 13-15kg / t, the coke reactivity is 20-27%, the strength of the coke after reaction is controlled to be >66%, M40 is 83-87%, and M10 is 6-8%; 2) Control the blast furnace cold air flow rate to 4000-4800m³ / min, the cold air pressure to 350-390KPa, the theoretical combustion temperature to 2450℃, the oxygen enrichment to 10000-18000m³ / h, the top pressure to 180-200KPa, the permeability index to 22000-25000, the molten iron physical heat to >1460℃, the silicon content of pig iron to 0.15-0.60%, and the gas utilization rate to 45-49%; 3) According to the operating parameters and technical and economic indicators such as cooling wall temperature, soft water temperature difference, gas utilization rate, material column permeability, Na20+K20 content in slag, fuel ratio, etc., combined with the raw material and fuel conditions, the slag basicity, pig iron silicon content, and the degree of central airflow development are adjusted in real time; 4) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 5) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

[0007] Working principle: In order to control production costs, inland steel mills in Yunnan usually use up all surrounding iron ore resources, and use imported ore to supplement the insufficient part. Therefore, the proportion of imported ore is low and normally between 20-35%. The Dahongshan pipeline with high alkali metals produced by Kunming Iron and Steel has a fine proportion of up to 60%, and the alkali metal content entering the furnace is >5.0kg / t. The alkali metal content is difficult to reach the indicator of <3.5kg / t of coastal steel mills, which is not conducive to blast furnace strengthening smelting, blast furnace longevity and low fuel ratio smelting. The high alkali metal load entering the furnace deteriorates the metallurgical properties of coke, the medium-temperature reduction pulverization of sintered ore doubles, the pellets expand abnormally, and the erosion and damage of refractory materials lead to poor permeability of the blast furnace column and reduced stability. It is difficult for the traditional blast furnace operation method to maintain stable and smooth furnace conditions for a long period of time, and the fuel consumption remains high. The main reasons are: (1) After low coke post-reaction strength (CSR) operation, alkali metals (potassium + sodium) have a positive catalytic effect on the carbon dissolution reaction of coke, the reactivity of coke increases, and a relatively large volume expansion occurs, resulting in a decrease in coke strength, a decrease in block size, and a large amount of coke fragments and powder, resulting in insufficient support for the column skeleton, which is prone to collapse and slippage, leading to increased fuel consumption. The coke post-reaction strength is controlled at >66%, and the fuel consumption is greatly reduced; (2) The blast furnace slag basicity operation is not conducive to the removal of alkali metals, and the blast furnace discharge The main channel for alkali metals is slag. The alkali content in slag can reach 90% of the alkali content entering the furnace. As the slag alkalinity decreases, the blast furnace's alkali removal capacity increases. At the same time, low alkalinity operation has a significant effect in reducing fuel consumption. (3) Conventional high-silicon pig iron smelting is not conducive to the removal of alkali metals. Properly reducing the silicon content in pig iron while ensuring appropriate furnace temperature can improve the blast furnace's alkali removal capacity. Kunming Iron and Steel's blast furnace is normally controlled at 0.15-0.30%, the silicon content in pig iron decreases by 0.1%, and the coke ratio decreases by 4kg / t. Low-silicon smelting is an effective means to reduce fuel consumption under high alkali metal conditions. (4) The MgO content in the industry's slag is usually controlled at 7.0-9.0%. Properly increasing the MgO content in the slag is beneficial to improving the fluidity of the slag, while improving the air and liquid permeability of the material column, and is also beneficial to alkali removal. Therefore, the MgO content in Kunming Iron and Steel's blast furnace slag is controlled at 9.5-10.0%. (5) Adopt the method of adding manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace. (6) Control the comprehensive furnace grade to about 56.6%, the slag ratio to be greater than 380kg / t, increase the slag volume, and increase the removal of alkali metals; (6) Regularly carry out alkali removal on the material reduction line to allow the alkali metals enriched in the furnace to fall into the furnace and be removed from the slag. (7) The gas flow distribution mode of the edge plus the center air flow takes into account both the appropriate development of the edge air flow when the raw material and fuel conditions are not good and the appropriate development of the center air flow to remove harmful elements such as zinc.

[0008] The method of low fuel ratio smelting under ultra-high alkali metal load conditions of the present invention is specifically to deal with the problems of alkali metal circulation enrichment in the furnace, affecting the stable and smooth operation of the furnace condition and the increase of the fuel ratio by optimizing the blast furnace thermal system, optimizing the slag making system, and regularly draining alkali in the blast furnace in the blast furnace smelting operation with large fluctuations in the quality of raw fuels when the comprehensive furnace grade is lower than 57%, the slag volume is greater than 370kg / t, the zinc load is greater than 0.4kg / t, the potassium and sodium load is greater than 5.5kg / t, the titanium load is greater than 13.0kg / t, the coke reactivity is higher than 25%, the strength after reaction is lower than 67%, the M40 is lower than 87%, and the M10 is higher than 6.0%. The problem of high harmful elements, serious catalytic damage of low-grade blast furnace operation coke, poor furnace stability, and high fuel ratio is greatly improved by adopting this method, and the influence of high alkali metal load on the stable and smooth operation of the furnace condition and fuel consumption is reduced, the furnace condition is stabilized to the maximum extent, the technical and economic indicators are improved, the cost is reduced, and the rational use of iron ore resources and coal resources with high alkali metal content is promoted. DETAILED DESCRIPTION

[0009] 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.

[0010] The present invention provides a method for smelting in a blast furnace with a low fuel ratio under high alkali metal load conditions, which is specifically implemented by the following steps: 1) Control the raw material and fuel conditions to be about 56.6% in the furnace, the slag ratio is greater than 380kg / t, the zinc load is 0.4-0.75kg / t, the potassium and sodium load is 5.5-7kg / t, the titanium load is 13-15kg / t, the coke reactivity is 20-27%, the strength of the coke after reaction is controlled to be >66%, M40 is 83-87%, and M10 is 6-8%; 2) Control the blast furnace cold air flow rate to 4000-4800m³ / min, the cold air pressure to 350-390KPa, the theoretical combustion temperature to 2450℃, the oxygen enrichment to 10000-18000m³ / h, the top pressure to 180-200KPa, the permeability index to 22000-25000, the molten iron physical heat to >1460℃, the silicon content of pig iron to 0.15-0.60%, and the gas utilization rate to 45-49%; 3) According to the operating parameters and technical and economic indicators such as cooling wall temperature, soft water temperature difference, gas utilization rate, material column permeability, Na20+K20 content in slag, fuel ratio, etc., combined with the raw material and fuel conditions, the slag basicity, pig iron silicon content, and the degree of central airflow development are adjusted in real time; 4) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 5) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

[0011] In the step 3), when the furnace condition is stable, the drum strength of the sintered ore is greater than 80%, the low-temperature reduction pulverization index of the sintered ore RDI+3.15mm is greater than 55%, the alkali metal load entering the furnace reaches 5.0kg / t, the fuel ratio is less than 520kg / t, the furnace temperature is normal, the permeability index is greater than 22000, and the comprehensive entering furnace grade is greater than 56.5%, conservative operation adjustment is adopted to reduce the slag basicity from 1.19 times to 1.15 times, reduce the silicon content of pig iron from 0.25-0.50% to 0.15-0.40%, increase the center coking ring from 1 ring to 2 rings, improve the center gas flow distribution, ensure the stability of the furnace condition, and reduce fuel consumption.

[0012] Normal furnace temperature means that when the pig iron contains 0.25-0.50% silicon, the physical heat is 1460-1490℃.

[0013] In the step 3), when the furnace condition is not stable, the air is blocked seriously, the furnace temperature fluctuates greatly, the silicon-sulfur double compliance rate is greater than 80%, the air permeability index is 20000-21000, and the fuel ratio is greater than 520kg / t, the fuel ratio is adjusted and reduced by centralized alkali removal.

[0014] The silicon and sulfur double standards refer to a silicon content of 0.15-0.60% and a sulfur content of less than 0.45%.

[0015] Example 1 According to the raw material and fuel conditions and production situation of Kunming Iron and Steel's 2500m³ blast furnace, the operating parameters are selected and adjusted, and the present invention is further described in conjunction with examples.

[0016] (1) Formulate appropriate operating guidelines: Kunming Iron and Steel blast furnace capacity 2500m³, cold air flow 4250m³ / min, cold air pressure 350KPa, T 2450℃, oxygen enrichment 14000m³ / h, top pressure setting 177KPa, permeability index 22000, molten iron physical heat > 1460℃, pig iron silicon content 0.25%, gas utilization rate 47%.

[0017] (2) Raw material and fuel conditions: comprehensive furnace grade 57%, slag ratio 381kg / t, zinc load 0.5kg / t, potassium and sodium load 5.57kg / t, titanium load 13.0kg / t, coke reactivity 25%, post-reaction strength 67%, M40 92%, M10 6.0%.

[0018] (3) Alkali metal load is calculated by computer by dividing the sum of alkali metal content of each batch of ore, coke and coal injection by the theoretical iron content of each batch. According to 51 tons of ore batch, 11 tons of coke batch, 39 tons of coal injection per hour, and the charge structure of 70% sintered ore + 30% pelletized ore, the alkali metal load of the above example = (51000*70%*0.210%+51000*30%*0.37%+11000*14%*1.3%+39000 / 8*12%*2.5%)*1000 / 29843=5.57kg / t.fe. The sintered ore blending ratio is shown in Table 1.

[0019] (4) According to the operating parameters and technical and economic indicators such as cooling wall temperature, soft water temperature difference, gas utilization rate, material column permeability, Na20+K20 content in slag, fuel ratio, etc., combined with the raw material and fuel conditions, real-time adjustments are made through slag basicity, pig iron silicon content, furnace top temperature, and central airflow development degree.

[0020] 1) When the furnace condition is stable, the drum strength of the sintered ore is 81.73%, the low-temperature reduction pulverization index of the sintered ore RDI+3.15mm is 57.89%, the alkali metal load into the furnace reaches 5.43kg / t, the fuel ratio is 513kg / t, the furnace temperature is normal (silicon content in pig iron is 0.28%, physical heat is 1470℃), the permeability index is greater than 22000, and the comprehensive furnace grade is 56.73%, conservative operation adjustments are adopted to reduce the slag basicity from 1.19 times to 1.15 times, the silicon content in pig iron is reduced from 0.25-0.50% to 0.15-0.40%, the center coking ring is increased from 1 ring to 2 rings, the center gas flow distribution is improved, the furnace condition is ensured to be stable, and the fuel consumption is reduced.

[0021] 2) When the furnace condition is not stable, the air is blocked seriously, the furnace temperature fluctuates greatly, the silicon and sulfur standards (silicon 0.15-0.60%, sulfur <0.45%) are >80%, the air permeability index is 20000-21000, and the fuel ratio is >520kg / t, the fuel ratio can be adjusted and reduced by centralized alkali drainage.

[0022] 3) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 4) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

[0023] Before the method of this embodiment was adopted, Kunming Iron and Steel's blast furnace smelting often experienced slag peeling, rising water temperature difference, large furnace temperature fluctuations, and suspended and slippery material phenomena. After the method of the present invention was adopted, there was no suspended and slippery material phenomenon for the whole month, and the blast furnace was stable and smooth for a long period of time. The technical and economic indicators were greatly improved, and the fuel ratio dropped from 525kg / t to 510kg / t. The quality of molten iron was not only improved, but also the silicon-sulfur double standard was increased from 90% to more than 95%. In addition, the proportion of self-produced ore pipelines with high alkali metal content in the mixed ore used for sintering ore increased from 40% to 55%, and 3% of the cost-effective fish roe powder was used to reduce the cost of ore by 45 yuan / ton.

[0024] Table 1 Ore structure of mixed ore used in sintering ore in Example 1 Example 2 According to the raw material and fuel conditions and production situation of Kunming Iron and Steel's 2500m³ blast furnace, the operating parameters are selected and adjusted, and the present invention is further described in conjunction with examples.

[0025] (1) Formulate appropriate operating guidelines: Kunming Iron and Steel blast furnace capacity 2500m³, cold air flow 4436m³ / min, cold air pressure 378KPa, T 2383℃, oxygen enrichment 12996m³ / h, top pressure setting 189KPa, permeability index 24041, molten iron physical heat 1478℃, pig iron silicon content 0.32%, gas utilization rate 46%.

[0026] (2) Raw material and fuel conditions: comprehensive furnace grade 56.23%, slag ratio 385kg / t, zinc load 0.57kg / t, potassium and sodium load 5.72kg / t, titanium load 13.9kg / t, coke reactivity 24.5%, post-reaction strength 68%, M40 89%, M10 6.5%.

[0027] (3) Alkali metal load is calculated by computer by dividing the sum of alkali metal content of each batch of ore, coke and coal injection by the theoretical iron content of each batch. According to 52 tons of ore batch, 12 tons of coke batch, 35 tons of coal injection per hour, and the charge structure of 68% sintered ore + 32% pelletized ore, the alkali metal load of the above example = (52000*72%*0.210%+52000*28%*0.370+12000*14%*1.3%+35000 / 8*12%*2.5%)*1000 / 29843=5.72kg / t.fe. The mixed ore proportion used for sintered ore is shown in Table 2.

[0028] (4) According to the operating parameters and technical and economic indicators such as cooling wall temperature, soft water temperature difference, gas utilization rate, material column permeability, Na20+K20 content in slag, fuel ratio, etc., combined with the raw material and fuel conditions, real-time adjustments are made through slag basicity, pig iron silicon content, furnace top temperature, and central airflow development degree.

[0029] 1) When the furnace condition is stable, the drum strength of the sintered ore is 81.08%, the low-temperature reduction pulverization index of the sintered ore RDI+3.15mm61.34%, the alkali metal load into the furnace reaches 5.72kg / t, the fuel ratio is 506kg / t, the furnace temperature is normal (silicon content in pig iron is 0.31%, physical heat is 1477℃), the permeability index is greater than 22000, and the comprehensive grade into the furnace is 56.59%, conservative operation adjustments are adopted to reduce the slag basicity from 1.19 times to 1.15 times, the silicon content in pig iron is reduced from 0.25-0.50% to 0.15-0.40%, the center coking ring is increased from 1 ring to 2 rings, the center gas flow distribution is improved, the furnace condition is ensured to be stable, and the fuel consumption is reduced.

[0030] 2) When the furnace condition is not stable, the air is blocked seriously, the furnace temperature fluctuates greatly, the silicon and sulfur standards (silicon 0.15-0.60%, sulfur <0.45%) are >80%, the air permeability index is 20000-21000, and the fuel ratio is >520kg / t, the fuel ratio can be adjusted and reduced by centralized alkali drainage.

[0031] 3) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 4) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

[0032] Before the method of this embodiment was adopted, Kunming Iron and Steel's blast furnace smelting often experienced slag peeling, rising water temperature difference, large furnace temperature fluctuations, and suspended and slippery material phenomena. After the method of the present invention was adopted, there was no suspended and slippery material phenomenon for the whole month, and the blast furnace was stable and smooth for a long period of time. The technical and economic indicators were greatly improved, and the fuel ratio dropped from 521kg / t to 506kg / t. The quality of molten iron was not only improved, but also the silicon-sulfur double standard was increased from 90% to more than 95%. In addition, the pipeline fine proportion of self-produced ore with high alkali metal content in the mixed ore used for sintering ore was increased from 17.5% to 30%, and 5.5% of the cost-effective 50 powder was used at the same time, reducing the cost of ore by 35 yuan / ton.

[0033] Table 2 Ore structure of mixed ore used in sintering ore in Example 2 Example 3 According to the raw material and fuel conditions and production situation of Kunming Iron and Steel's 2500m³ blast furnace, the operating parameters are selected and adjusted, and the present invention is further described in conjunction with examples.

[0034] (1) Formulate appropriate operating guidelines: Kunming Iron and Steel blast furnace capacity 2500m³, cold air flow 4154m³ / min, cold air pressure 358KPa, T 2464℃, oxygen enrichment 13812m³ / h, top pressure setting 176KPa, permeability index 22540, molten iron physical heat 1471℃, pig iron silicon content 0.27%, gas utilization rate 49%.

[0035] (2) Raw material and fuel conditions: comprehensive furnace grade 56.48%, slag ratio 382kg / t, zinc load 0.55kg / t, potassium and sodium load 6.04kg / t, titanium load 13.3kg / t, coke reactivity 25.7%, post-reaction strength 69%, M40 94%, M10 6.1%.

[0036] (3) Alkali metal load is calculated by computer by dividing the sum of alkali metal content of each batch of ore, coke and coal injection by the theoretical iron content of each batch. According to 55 tons of ore batch, 13 tons of coke batch, 37 tons of coal injection per hour, and the charge structure of 69% sintered ore + 31% pelletized ore, the alkali metal load of the above example = (69000*72%*0.210%+69000*28%*0.37%+13000*14%*1.3%+37000 / 8*12%*2.5%)*1000 / 29843=6.04kg / t.fe. The mixed ore proportion used for sintered ore is shown in Table 3.

[0037] (4) According to the operating parameters and technical and economic indicators such as cooling wall temperature, soft water temperature difference, gas utilization rate, material column permeability, Na20+K20 content in slag, fuel ratio, etc., combined with the raw material and fuel conditions, real-time adjustments are made through slag basicity, pig iron silicon content, furnace top temperature, and central airflow development degree.

[0038] 1) When the furnace condition is stable, the drum strength of the sintered ore is 82.18%, the low-temperature reduction pulverization index of the sintered ore RDI+3.15mm is 58.43%, the alkali metal load into the furnace reaches 6.01kg / t, the fuel ratio is 517kg / t, the furnace temperature is normal (silicon content in pig iron is 0.35%, physical heat is 1481℃), the permeability index is greater than 22540, and the comprehensive furnace grade is 56.23%, conservative operation adjustments are adopted to reduce the slag basicity from 1.19 times to 1.15 times, the silicon content in pig iron is reduced from 0.25-0.50% to 0.15-0.40%, and the center coking is increased from 1 ring to 2 rings to improve the center gas flow distribution, ensure the stability of the furnace condition, and reduce fuel consumption.

[0039] 2) When the furnace condition is not stable, the air is blocked seriously, the furnace temperature fluctuates greatly, the silicon and sulfur standards (silicon 0.15-0.60%, sulfur <0.45%) are >80%, the air permeability index is 20000-21000, and the fuel ratio is >520kg / t, the fuel ratio can be adjusted and reduced by centralized alkali drainage.

[0040] 3) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 4) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

[0041] Before the method of this embodiment was adopted, slag skin often fell off, water temperature difference increased, furnace temperature fluctuated greatly, and suspended and slipped materials occurred in Kunming Iron and Steel's blast furnace smelting. After the method of the present invention was adopted, there was no suspended and slipped material phenomenon for the whole month, and the blast furnace was stable and smooth for a long period of time. The technical and economic indicators were greatly improved, and the fuel ratio dropped from 523kg / t to 511kg / t. The quality of molten iron was not only improved, but also the silicon and sulfur double standards were increased from 90% to more than 95%. In addition, the pipeline fine proportion of self-produced ore with high alkali metal content in the mixed ore used for sintering ore increased from 28% to 56%.

[0042] Table 3 Ore structure of mixed ore used in sintering ore in Example 3 .

Claims

1. A method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions, characterized in that: To do this, follow these steps: 1) Control the raw material and fuel conditions to be about 56.6% in the furnace, the slag ratio is greater than 380kg / t, the zinc load is 0.4-0.75kg / t, the potassium and sodium load is 5.5-7kg / t, the titanium load is 13-15kg / t, the coke reactivity is 20-27%, the strength of the coke after reaction is controlled to be >66%, M40 is 83-87%, and M10 is 6-8%; 2) Control the blast furnace cold air flow rate to 4000-4800m³ / min, the cold air pressure to 350-390KPa, the theoretical combustion temperature to 2450℃, the oxygen enrichment to 10000-18000m³ / h, the top pressure to 180-200KPa, the permeability index to 22000-25000, the molten iron physical heat to >1460℃, the silicon content of pig iron to 0.15-0.60%, and the gas utilization rate to 45-49%; 3) According to the cooling wall temperature, soft water temperature difference, gas utilization rate, column permeability, Na20+K20 content in slag, fuel ratio and raw fuel conditions, the slag basicity, pig iron silicon content and central airflow development degree are adjusted in real time; 4) Use appropriate addition of manganese ore and fluorite to wash the furnace from time to time to accelerate the reduction of alkali metal oxides, thereby increasing the circulation and enrichment of alkali metals in the furnace; 5) Carry out alkali removal from the material reduction line regularly and centrally, so that the alkali metals enriched in the furnace will fall off into the furnace cylinder and be removed from the slag.

2. The method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions according to claim 1, characterized in that: In the step 3), when the furnace condition is stable, the drum strength of the sintered ore is greater than 80%, the low-temperature reduction pulverization index of the sintered ore RDI+3.15mm is greater than 55%, the alkali metal load entering the furnace reaches 5.0kg / t, the fuel ratio is less than 520kg / t, the furnace temperature is normal, the permeability index is greater than 22000, and the comprehensive entering furnace grade is greater than 56.5%, conservative operation adjustment is adopted to reduce the slag basicity from 1.19 times to 1.15 times, reduce the silicon content of pig iron from 0.25-0.50% to 0.15-0.40%, increase the center coking ring from 1 ring to 2 rings, improve the center gas flow distribution, ensure the stability of the furnace condition, and reduce fuel consumption.

3. The method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions according to claim 2, characterized in that: Normal furnace temperature means that when the pig iron contains 0.25-0.50% silicon, the physical heat is 1460-1490℃.

4. The method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions according to claim 1, characterized in that: In the step 3), when the furnace condition is not stable, the air is blocked seriously, the furnace temperature fluctuates greatly, the silicon-sulfur double compliance rate is greater than 80%, the air permeability index is 20000-21000, and the fuel ratio is greater than 520kg / t, the fuel ratio is adjusted and reduced by centralized alkali removal.

5. The method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions according to claim 4, characterized in that: The silicon and sulfur double standards refer to a silicon content of 0.15-0.60% and a sulfur content of less than 0.45%.

6. The method for smelting in a blast furnace with low fuel ratio under high alkali metal load conditions according to claim 1, characterized in that: The method reduces the grade, increases the amount of slag, increases the MgO in the slag, optimizes the matrix adjustment, and adjusts the balanced development of the two airflows at the center and edge of the blast furnace to improve the removal rate of harmful elements, especially the removal of alkali metals and zinc.

Images