A method for quickly restoring blast furnace conditions

Abstract

A method for quickly restoring the condition of a blast furnace can restore abnormal and abnormal conditions to normal in less than one week by systematically adjusting the air supply system, heat system, slag making system and charging system of the blast furnace. The invention has strong systematicity and operability, avoids the use of fluxes such as manganese ore and fluorite that have a greater impact on the blast furnace, saves the cost of restoring the condition of the blast furnace to the maximum extent, and greatly reduces the labor intensity of blast furnace workers.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and relates to a method for rapidly recovering the condition of a blast furnace for ironmaking. Background Art

[0002] Blast furnace is a reactor with complex smelting process in metallurgical industry. Due to its requirements on raw materials, equipment and operation, any change in the blast furnace production process may cause the blast furnace to change from normal production state to abnormal or abnormal condition. Abnormal and abnormal conditions are usually manifested as a sharp decline in blast furnace air volume, frequent burning of tuyere, and a sharp drop in output.

[0003] When the furnace condition enters an abnormal or malfunctioning state, blast furnace managers and operators usually adopt measures such as reducing the smelting intensity of the blast furnace and increasing the fuel ratio, but these measures are not effective, and usually cause this abnormal and malfunctioning state to last for weeks or even months or years, causing significant economic losses to steel companies. In addition to the above measures, some iron smelters will also add manganese ore or fluorite to deal with furnace condition fluctuations. These two minerals will greatly reduce the melting point and grade of the ore, causing the soft melting zone to move upward, destroying the stable operation furnace type, and even corroding the refractory materials inside the blast furnace, which has the risk of further exacerbating furnace condition fluctuations. Therefore, it is very necessary to develop a method to quickly restore the blast furnace condition. Summary of the invention

[0004] The purpose of the present invention is to provide a method for quickly restoring the condition of a blast furnace, which can enable the blast furnace to quickly restore abnormal or abnormal condition to normal state by systematically adjusting various systems of the blast furnace while using less additional raw materials.

[0005] The technical solution of the present invention:

[0006] A method for quickly restoring a blast furnace condition, the process steps comprising:

[0007] S1: After the blast furnace is shut down and the damaged tuyere is replaced, the tuyere is blocked and the air is supplied. The number of blocked tuyere accounts for 20%-30% of the total number of tuyere, and the blocked tuyere is evenly distributed on the circumference of the furnace. When supplying air, stop enriching oxygen in the cold air;

[0008] S2: Increase the weight of the coke batch while reducing the coke load. The weight of the coke batch is increased until the average thickness of the coke layer at the furnace waist is greater than 230mm, and the coke load is reduced to 80%-90% of the load during normal production. The minimum coke batch weight and load calculation formula are as follows:

[0009]

[0010] P=AP 正常 (2)

[0011] Where: w焦 is the minimum weight of each batch of coke, kg; r 炉腰 is the furnace waist radius, m; w 水 is the moisture content of coke, %; P is the target adjustment load; A is the adjustment coefficient, ranging from 80% to 90%; P 正常 is the coke load during normal production;

[0012] S3: Adjust the slag composition, add silica to reduce the CaO / SiO2 value of the slag to 90% to 97% of normal production, the Al2O3 content in the slag is less than 16%, and the MgO / Al2O3 value is greater than 0.4;

[0013] S4: Control the temperature of the molten iron to 1500-1530°C;

[0014] S5: Open the tuyere to supply air according to the air volume recovery situation. When the air volume is greater than 95% of the normal smelting air volume, all blocked tuyere are opened.

[0015] The method for stabilizing the temperature of molten iron to 1500-1530° C. in S4:

[0016] a. Use coal quantity to adjust the fuel ratio. When the molten iron temperature is lower than 1500℃, increase the coal quantity to increase the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours. Measure the molten iron temperature every hour. When the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal quantity and fuel ratio. When the molten iron temperature is lower than 1500℃ after one cycle of increasing the fuel ratio, increase the fuel ratio in the next cycle.

[0017] b. Use the amount of coal to adjust the fuel ratio. When the molten iron temperature is higher than 1530℃, reduce the amount of coal to reduce the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours; measure the molten iron temperature every hour, and when the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal amount and fuel ratio; when the molten iron temperature is higher than 1530℃ after increasing the fuel ratio for a cycle, reduce the fuel ratio in the next cycle;

[0018] c. The molten iron temperature measured in the current hour is between 1500 and 1530°C, and the fuel ratio is controlled according to the current cycle.

[0019] The method of opening the air outlet to supply air when the air volume is restored in S5 is as follows:

[0020] a. The air volume is less than 75% of the normal air volume. The hourly average air volume increases by 300m 3 / min, open a blocked vent;

[0021] b. The air volume is greater than 75% of the normal air volume. The hourly average air volume increases by 200m 3 / min, open a blocked vent;

[0022] c. When the air volume reaches 95% of the normal smelting air volume, if there are still tuyere that have not been opened in operations a and b, all the remaining blocked tuyere shall be opened at one time.

[0023] The beneficial effects of the present invention are as follows: by systematically adjusting the air supply system, heat system, slag making system and charging system of the blast furnace, the abnormal and abnormal furnace conditions can be restored to normal in less than 1 week; when adjusting the furnace conditions, only silica, a flux that is beneficial to the composition of molten iron in the blast furnace, is used, avoiding the use of manganese ore, fluorite and other fluxes that have a greater impact on the composition, operation and cost of the blast furnace molten iron, thereby avoiding the increase of molten iron cost when adjusting the furnace conditions; the furnace condition recovery measures are highly systematic and operable, greatly reducing the labor intensity of blast furnace workers; DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the embodiments.

[0025] A method for quickly restoring the condition of a blast furnace, the process steps of which include:

[0026] S1: After the blast furnace is shut down and the damaged tuyere is replaced, the tuyere is blocked and the air is supplied. The number of blocked tuyere accounts for 20%-30% of the total number of tuyere, and the blocked tuyere is evenly distributed on the circumference of the furnace. When supplying air, stop enriching oxygen in the cold air; the effective volume of the fluctuating blast furnace is 2580m 3 There are 30 tuyere in total, the blocked tuyere numbers are 1#, 6#, 10#, 14#, 17#, 22#, 26#, the blocked tuyere are evenly distributed on the circumference of the furnace, and the number of blocked tuyere accounts for 23% of all tuyere. After the tuyere is blocked, the oxygen and air supply operation is stopped.

[0027] S2: Increase the coke batch weight and reduce the coke load: The coke batch weight is increased until the average thickness of the coke layer at the furnace waist is greater than 230mm, and the coke load is reduced to 80% to 90% of the load during normal production. The minimum coke batch weight and load calculation formula are as follows:

[0028]

[0029] P=AP 正常 (2)

[0030] Where: w 焦 is the minimum weight of each batch of coke, kg; r 炉腰 is the furnace waist radius, m; w 水 is the moisture content of coke, %; P is the target adjustment load; A is the adjustment coefficient, 80%-90%; P 正常The coke load during normal production. The fluctuating blast furnace waist diameter is 12.6m, the load during normal smelting is 4.65, and the coke batch is 13650kg (including coke moisture, with a moisture content of 3.5%). According to formula (1), the coke batch during adjustment is 14384kg, and the load is reduced to 4.0, which is 86% of the load during normal smelting.

[0031] S3: Adjust slag composition: Add silica to reduce the CaO / SiO2 value of slag to 90%-97% of normal production, the Al2O3 content in the slag is less than 16%, and the MgO / Al2O3 value is greater than 0.4; when adjusting the furnace condition, add 400kg silica to each batch of ore, the CaO / SiO2 value of the slag is 1.14, which is 1.20-1.25 during normal smelting. The CaO / SiO2 value during adjustment is 91.2%-95% of normal smelting. The Al2O3 content of the slag during adjustment is less than 15.58%, and the MgO / Al2O3 value is greater than 0.43.

[0032] S4: Control the molten iron temperature to a higher range: Control the molten iron temperature to 1500-1530°C. The specific steps of the control method are as follows:

[0033] a. Use coal quantity to adjust the fuel ratio. When the molten iron temperature is lower than 1500℃, increase the coal quantity to increase the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours. Measure the molten iron temperature every hour. When the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal quantity and fuel ratio. When the molten iron temperature is lower than 1500℃ after one cycle of increasing the fuel ratio, increase the fuel ratio in the next cycle.

[0034] b. Use the amount of coal to adjust the fuel ratio. When the molten iron temperature is higher than 1530℃, reduce the amount of coal to reduce the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours. Measure the molten iron temperature every hour. When the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal amount and fuel ratio. When the molten iron temperature is higher than 1530℃ after increasing the fuel ratio for one cycle, reduce the fuel ratio in the next cycle.

[0035] c. The molten iron temperature measured in the current hour is between 1500 and 1530°C, and the fuel ratio is controlled according to the current cycle.

[0036] When the fluctuating blast furnace condition began to be adjusted, the molten iron temperature was 1463°C. By controlling the amount of coal, the fuel ratio was increased by 3kg per hour, and temperature measurement and monitoring were performed every hour, the molten iron temperature increased from 1463°C in the first hour to 1504°C in the seventh hour. Subsequently, the fuel ratio operation was performed in the seventh hour, and the molten iron temperature was stabilized at 1504-1530°C.

[0037] S5: Opening the tuyere: Open the tuyere to supply air according to the air volume recovery situation. When the air volume is greater than 95% of the normal smelting air volume, all blocked tuyere are opened. The specific operation steps are as follows:

[0038] a. The air volume is less than 75% of the normal air volume. The hourly average air volume increases by 300m 3 / min, open a blocked vent;

[0039] b. The air volume is greater than 75% of the normal air volume. The hourly average air volume increases by 200m 3 / min, open a blocked vent;

[0040] c. When the air volume reaches 95% of the normal smelting air volume, if there are still tuyere that have not been opened in operations a and b, all the remaining blocked tuyere shall be opened at one time.

[0041] Fluctuating blast furnace normal production air volume 5000m 3 / min.

[0042] The first hour wind volume is 2731m 3 / min;

[0043] The second hour wind volume is 3263m 3 / min, the wind volume increased by 532m3 compared with the previous hour 3 / min, open the blocked 1# tuyere within the third hour;

[0044] The wind volume in the third hour is 3495m 3 / min, the wind volume increased by 232m3 compared with the previous hour 3 / min, no vent opening operation was performed within the fourth hour;

[0045] Wind volume in the fourth hour: 3766m 3 / min, the wind volume increased by 271m3 compared with the previous hour 3 / min, an increase of 503m compared to the second hour 3 / min, open the blocked 6# tuyere within the fifth hour;

[0046] Wind volume in the fourth hour: 3766m 3 / min, which has reached 75% of the normal smelting air volume;

[0047] Wind volume in the fifth hour: 4065m 3 / min, an increase of 299m compared with the previous hour 3 / min, open the blocked 22# vent within the sixth hour;

[0048] Wind volume in the sixth hour: 4268m 3 / min, the wind volume increased by 203m3 compared with the previous hour 3 / min, open the blocked 17# tuyere within the seventh hour;

[0049] Wind volume in the seventh hour: 4585m 3 / min, the wind volume increased by 371m3 compared with the previous hour 3 / min, open the blocked 14# tuyere within the eighth hour;

[0050] The eighth hour wind volume is 4803m 3 / min, the air volume increased by 218m3 compared with the previous hour 3 / min, in the ninth hour, the blocked 10# and 26# tuyere were opened;

[0051] Air volume in the 16th hour: 5016m 3 / min, the normal smelting air volume has been reached, and the enhanced smelting operation has begun. At this point, the blast furnace condition has returned to normal.

Claims

1. A method for rapidly restoring a blast furnace condition, characterized in that The process steps include: S1: After the blast furnace is shut down and the damaged tuyere is replaced, the tuyere is blocked and air is supplied. The number of blocked tuyere accounts for 20% to 30% of the total number of tuyere, and the blocked tuyere is evenly distributed on the circumference of the furnace. When supplying air, oxygen enrichment in the cold air is stopped; S2: Increase the weight of the coke batch while reducing the coke load. The weight of the coke batch is increased until the average thickness of the coke layer at the furnace waist is greater than 230mm, and the coke load is reduced to 80% to 90% of the load during normal production. The minimum coke batch weight and load calculation formula are as follows: P=AP 正常 Where: w 焦 is the minimum weight of each batch of coke, kg; r 炉腰 is the furnace waist radius, m; w 水 is the moisture content of coke, %; P is the target adjustment load; A is the adjustment coefficient, ranging from 80% to 90%; P 正常 is the coke load during normal production; S3: Adjust the slag composition, add silica to reduce the CaO / SiO2 value of the slag to 90% to 97% of normal production, the Al2O3 content in the slag is less than 16%, and the MgO / Al2O3 value is greater than 0.4; S4: Control the temperature of the molten iron to 1500-1530°C; S5: Open the tuyere to supply air according to the air volume recovery situation. When the air volume is greater than 95% of the normal smelting air volume, all blocked tuyere are opened. Specific operation method: a. The air volume is less than 75% of the normal air volume. The hourly average air volume increases by 300m 3 / min, open a blocked vent; b. The air volume is greater than 75% of the normal air volume. The hourly average air volume increases by 200m 3 / min, open a blocked vent; c. When the air volume reaches 95% of the normal smelting air volume, if there are still tuyere that have not been opened in operations a and b, all the remaining blocked tuyere shall be opened at one time.

2. A method for rapidly restoring a blast furnace condition according to claim 1, characterized in that Method for stabilizing the molten iron temperature to 1500-1530°C in S4: a. Use coal quantity to adjust the fuel ratio. When the molten iron temperature is lower than 1500℃, increase the coal quantity to increase the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours. Measure the molten iron temperature every hour. When the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal quantity and fuel ratio. When the molten iron temperature is lower than 1500℃ after one cycle of increasing the fuel ratio, increase the fuel ratio in the next cycle. b. Use the amount of coal to adjust the fuel ratio. When the molten iron temperature is higher than 1530℃, reduce the amount of coal to reduce the fuel ratio by 1-3kg / t per hour, with a cycle of 2-4 hours; measure the molten iron temperature every hour, and when the molten iron temperature is within the range of 1500-1530℃, stabilize the increased coal amount and fuel ratio; when the molten iron temperature is higher than 1530℃ after increasing the fuel ratio for a cycle, reduce the fuel ratio in the next cycle; c. The molten iron temperature measured in the current hour is between 1500 and 1530°C, and the fuel ratio is controlled according to the current cycle.

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