Treatment method for blast furnace blow-in hearth accumulation

Abstract

The invention belongs to the technical field of blast furnace smelting, and particularly discloses a blast furnace blow-in hearth accumulation treatment method, which comprises three stages of a basic stabilization stage, an ore-coke ratio optimization stage and an enhanced smelting stage, through a progressive strategy of first stabilization and then tapping of the three stages, air volume is stabilized to establish a reference furnace condition, and the ore-coke ratio is slowly increased to improve the thermodynamic state of a hearth. And finally, the capacity release is realized through air extraction. The problems of poor liquid permeability, thermal imbalance and limited productivity are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnace smelting, in particular to a treatment method for furnace hearth accumulation of a blast furnace during start-up. BACKGROUND

[0002] At the initial stage of blast furnace start-up, dense slag-iron mixture is deposited in the internal and side wall of the furnace hearth due to improper water cooling or operation, forming an accumulation layer, which is manifested by a significant decrease in liquid permeability, limited air volume (such as a sudden increase in pressure difference ΔP when the air volume is increased to 4300 m 3 / min), thermal system imbalance (0.3%-0.5% fluctuation of molten iron [Si]), uneven molten iron temperature (temperature difference of more than 30℃ between different iron tapholes), and other problems. Such accumulation can cause the following vicious cycle: Gas flow distribution deterioration: the central gas flow is blocked, the edge gas flow is enhanced, the "double-peak gas flow" distribution is destroyed, and the pressure difference is increased, which is easy to cause suspended material.

[0003] Thermodynamic imbalance: unburned coal powder accumulates in the dead material column, the combustion rate is low, the thermal reserve of the furnace hearth is insufficient, the physical heat of the molten iron decreases, and the slag-iron fluidity is poor.

[0004] Coke deterioration: the powder coke rate increases (>25%), the liquid permeability is further deteriorated, the cyclone zone is shortened, and the excessive coal injection exacerbates the blockage.

[0005] The traditional method is to simply reduce the air volume or add coke for treatment, but the effect is limited and cannot systematically solve the accumulation problem. Therefore, a phased and dynamic control method is needed to restore the activity of the furnace hearth. SUMMARY

[0006] The purpose of the present application is to provide a treatment method for furnace hearth accumulation of a blast furnace during start-up, which realizes the activation of the furnace hearth by a progressive strategy of "stabilization first and attack later" in three stages (basic stabilization period, ore-coke ratio optimization period, and intensified smelting period), and solves the problems of poor liquid permeability, thermal imbalance, and limited production capacity.

[0007] To achieve the above purpose, the basic scheme provided by the present application is: a treatment method for furnace hearth accumulation of a blast furnace during start-up, comprising the following three treatment stages: 1) Basic stabilization period: control the air volume at 4000±20 m 3 / min, the pressure difference ΔP≤170kPa, the gas permeability index K value≤5.5, the initial coke load is set to 3.2 times, and the coal injection amount≤60kg / t; 2) Ore-coke ratio optimization period: gradually increase the coke load to 3.4-3.5 times, gradually increase the air temperature from 1000℃ to 1060℃, and monitor the material speed and static pressure fluctuation in real time and perform early warning and air volume reduction operation; 3) Enhanced smelting period: Under the premise that the pressure difference ΔP ≤ 173 kPa for 3 consecutive days and the air permeability index ≥ 5.5, the air volume is increased to 4500 m³ in stages. 3 / min, and set up emergency handling mechanisms for material suspension and abnormal furnace temperature.

[0008] Furthermore, during the basic stabilization period, the target molten iron [Si] content is 0.45%-0.7%, the physical temperature PT≥1490℃, and the slag basicity CaO / SiO2=1.0-1.05.

[0009] Furthermore, the daily coke load increase during the ore-coke ratio optimization period shall not exceed 0.05.

[0010] Furthermore, during the optimization period of the ore-coke ratio, the material rate and static pressure fluctuations are monitored every hour. When the pressure difference ΔP ≥ 173 kPa, an early warning is issued, and when the pressure difference ΔP ≥ 178 kPa, the ventilation is reduced.

[0011] Furthermore, the increase in air temperature every 24 hours during the optimization period of the ore-coke ratio is ≤20℃.

[0012] Furthermore, the increase in air volume during each stage of the enhanced smelting period is 50m³. 3 / min.

[0013] Furthermore, after each stage of the air-lifting operation during the enhanced smelting period is completed, observation for 6-10 hours is required. Only after confirming that the pressure difference ΔP decreases by ≥3 kPa can the next stage of air-lifting operation continue until the air volume is increased to 4500 m³ / h. 3 / min.

[0014] Furthermore, the emergency response includes the following: 1) Warning sign of material suspension: Immediately reduce airflow to 3840m 3 / min, stop oxygen and add clean coke 3 batches, each batch is 5 tons, the coke layer thickness increases by 450mm, and the center temperature is controlled at 400-500℃; 2) Furnace temperature anomaly: If the molten iron [Si] content is <0.3%, the blast temperature will be raised to 1130℃ within 10 minutes and two batches of coke will be added; if the molten iron [Si] content is >0.8%, the blast temperature will be lowered to 1080℃ within 5 minutes and the coal injection rate will be reduced by 10kg / t.

[0015] Compared with the prior art, the advantages of this invention are: 1. This invention gradually restores the permeability of the dead material column by controlling the air volume, ore-coke ratio, and heating regime in stages, thereby improving the permeability of the hearth and restoring the air volume to 4500 m³ / h. 3 With a speed of over 10 min, the uniformity of molten iron temperature is improved, and the temperature difference between each tap is ≤10℃; the coke pulverization rate is reduced to below 15%, and the production capacity is increased by 8%-10%.

[0016] 2. During the basic stabilization period, pressure fluctuations are avoided by stabilizing the airflow distribution.

[0017] 3. During the ore-coke ratio optimization period, the thermodynamic state of the hearth is improved by adjusting the load and blast temperature.

[0018] 4. Strengthen the release of production capacity during the smelting period, and at the same time, dynamically respond to abnormal operating conditions to form a closed-loop control. Detailed Implementation

[0019] The present invention will be further described in detail below through specific embodiments: A method for handling blast furnace hearth buildup during start-up includes the following three stages: Basic stabilization period: Control the air volume at 4000±20m³ 3 / min, pressure difference ΔP≤170kPa, permeability index K value≤5.5, initial coke load set to 3.2 times, pulverized coal injection rate≤60kg / t, target molten iron [Si] content is 0.45%-0.7%, physical temperature PT≥1490℃, slag basicity CaO / SiO2=1.0-1.05; During the ore-coke ratio optimization period: gradually increase the coke load to 3.4-3.5 times, with a daily increase of no more than 0.05; gradually increase the blast temperature from 1000℃ to 1060℃, with an increase of ≤20℃ every 24 hours; monitor the material rate and static pressure fluctuations every hour, and start the warning when the pressure difference ΔP ≥ 173kPa, and start reducing the blast when the pressure difference ΔP ≥ 178kPa; Intensified smelting period: Under the premise of a pressure difference ΔP ≤ 173 kPa for 3 consecutive days and an air permeability index ≥ 5.5, the air volume is increased to 4500 m³ in stages. 3 / min, with an increase in air volume of 50m³ / min per stage. 3 / min. After each stage of air increase operation is completed, observation is required for 6-10 hours. Once the pressure difference ΔP decrease is confirmed to be ≥3kPa, the next stage of air increase operation can be continued until the air volume is increased to 4500m³ / min. 3 / min; and set up emergency handling mechanisms for material suspension and abnormal furnace temperature, including the following emergency handling: Warning of material buildup: Immediately reduce airflow to 3840m 3 / min, stop oxygen and add clean coke 3 batches, each batch is 5 tons, the coke layer thickness increases by 450mm, and the center temperature is controlled at 400-500℃; Furnace temperature anomaly: If the molten iron [Si] content is <0.3%, raise the blast temperature to 1130℃ within 10 minutes and add 2 batches of coke; if the molten iron [Si] content is >0.8%, lower the blast temperature to 1080℃ within 5 minutes and reduce the coal injection rate by 10kg / t.

[0020] The specific implementation of the above method in the blast furnace of Baosteel is as follows, and the following scheme was implemented from June 12, 2025 to July 1, 2025: Basic stabilization period (June 12-15): ① Initial parameter control: air volume 4000m³ 3 / min, coke load 3.2 times, pulverized coal injection rate 62.93 kg / t, blast temperature 1000℃, ② Monitoring and Adjustment: Real-time monitoring of ΔP and K values, and verification of the top material flow distribution every 8 hours, as shown in Table 1. During this stage, the monitored ΔP and K values ​​are between 158.52-172.51 kPa and 5.31-6.29 kPa, respectively. ③ Optimization of thermal regime: The [Si] content of molten iron was stabilized at 0.5%-0.6% and PT≥1490℃ by monitoring with an online spectrometer.

[0021] 2) Optimization period for ore-coke ratio (June 16-22): ①Load adjustment: On June 16, the coke load increased to 3.429 times, the blast temperature rose to 1070℃, and the pulverized coal injection rate was 54.88 kg / t; ② Differential pressure management: When ΔP>173kPa, reduce airflow by 50m. 3 / min and check the status of the air vents.

[0022] 3) Enhanced smelting period (June 23 - July 1): ① Air volume increase operation: On June 23, the air volume was increased to 4400 m³ / h. 3 After observing for 8 hours and confirming that the ΔP decrease is ≥3kPa, the pressure is further increased to 4500m. 3 / min.

[0023] Table 1: Monitored differential pressure values ​​and K values ​​from June 12, 2025 to June 22, 2025 Date O / C Target Pressure Differential K Value Tf Wind Temperature Coal Ratio Fuel Ratio 6 / 12 3.217 158.52 6.29 2130 1000 62.93 556.70 6 / 13 3.404 168 5.41 2130 1020 41.50 572.65 6 / 14 3.429 169.79 5.31 2130 1020 58.86 570.95 6 / 15 3.429 172.51 5.42 2130 1050 54.85 571.30 6 / 16 3.429 171.15 5.38 2130 1070 54.88 572.14 6 / 17 3.310 172.51 5.42 2130 1060 55.32 572.20 6 / 18 3.380 168.26 5.45 2130 1060 51.68 572.96 6 / 19 3.475 172.51 5.42 2130 1060 55.87 566.65 6 / 20 3.498 171.51 5.66 2130 1068 79.36 577.76 6 / 21 3.428 174 5.64 2130 1060 72.37 583.33 6 / 22 3.392 170.3 5.52 2130 1060 57.95 578.27 In addressing the enlargement of the dead material column in the center of the hearth, reducing the coke load and controlling the pulverized coal injection rate can alleviate the deterioration of the dead material column. Continuous monitoring of the hearth's reactivity recovery is crucial, with particular emphasis on the furnace core temperature. Gradually restore the blast volume to 4500 m³ / h. 3 When the flow rate exceeds a certain threshold, the permeability of the dead material column is improved to a normal level.

[0024] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for treating the accumulation of material in the hearth during blast furnace opening, characterized in that, It includes the following three processing stages: Basic stabilization period: Control the air volume at 4000±20m³ 3 / min, pressure difference ΔP≤170kPa, air permeability index K value≤5.5, initial coke load set to 3.2 times, pulverized coal injection rate≤60kg / t; During the ore-coke ratio optimization period: gradually increase the coke load to 3.4-3.5 times, gradually increase the blast temperature from 1000℃ to 1060℃, monitor the material speed and static pressure fluctuations in real time, and carry out early warning and blast reduction operations; Intensified smelting period: Under the premise of a pressure difference ΔP ≤ 173 kPa for 3 consecutive days and an air permeability index ≥ 5.5, the air volume is increased to 4500 m³ in stages. 3 / min, and set up emergency handling mechanisms for material suspension and abnormal furnace temperature.

2. The method for handling the accumulation of blast furnace hearth during blast furnace opening according to claim 1, characterized in that, During the basic stabilization period, the target molten iron [Si] content is 0.45%-0.7%, the physical temperature PT≥1490℃, and the slag basicity CaO / SiO2=1.0-1.

05.

3. The method for handling the accumulation of material in the hearth during blast furnace opening according to claim 1, characterized in that, The daily increase in coke load during the optimization period of the ore-coke ratio shall not exceed 0.

05.

4. The method for treating blast furnace hearth accumulation during blast furnace opening according to claim 1, characterized in that, During the optimization period of the ore-coke ratio, the material rate and static pressure fluctuations are monitored every hour. When the pressure difference ΔP ≥ 173 kPa, an early warning is issued, and when the pressure difference ΔP ≥ 178 kPa, the ventilation is reduced.

5. The method for treating blast furnace hearth accumulation during blast furnace opening according to claim 1, characterized in that, The increase in air temperature during the optimization period of the ore-coke ratio is ≤20℃ every 24 hours.

6. A method for treating blast furnace hearth accumulation during blast furnace start-up according to claim 1, characterized in that, The increase in air volume during each stage of the intensive smelting period is 50m. 3 / min.

7. The method for treating blast furnace hearth accumulation during blast furnace opening according to claim 1, characterized in that, After each stage of the blasting operation during the enhanced smelting period, observation for 6-10 hours is required. Once the pressure difference ΔP decreases by ≥3 kPa, the next stage of blasting operation can continue until the air volume is increased to 4500 m³ / h. 3 / min.

8. A method for treating blast furnace hearth buildup during start-up according to claim 1, characterized in that, The emergency response includes the following: 1) Warning sign of material suspension: Immediately reduce airflow to 3840m 3 / min, stop oxygen and add clean coke 3 batches, each batch is 5 tons, the coke layer thickness increases by 450mm, and the center temperature is controlled at 400-500℃; 2) Furnace temperature anomaly: If the molten iron [Si] content is <0.3%, the blast temperature will be raised to 1130℃ within 10 minutes and two batches of coke will be added; if the molten iron [Si] content is >0.8%, the blast temperature will be lowered to 1080℃ within 5 minutes and the coal injection rate will be reduced by 10kg / t.