Method for smoothly tapping first-time iron during blow-in of blast furnace

Abstract

The invention discloses a method for smoothly tapping first-time iron during blow-in of a blast furnace. In the blow-in process of the blast furnace, a series of measures of controlling the granularity of bottom coke, controlling the coke ratio of the whole furnace and slag R, optimizing a sleeper filling mode, quickly opening an iron notch after air supply to eliminate a hearth gas circulation dead zone, setting a main channel sand dam to prolong the slag spraying time of the iron notch and the like are taken. By setting the control points, the heat exchange effect of the hearth and the coal gas can be effectively improved, the slag iron temperature can be effectively increased at the earlier stage of the same full-furnace coke ratio, molten iron is low in Si and S, the physical temperature is sufficient, the slag iron can flow out smoothly, water slag can be flushed through iron for the first time, and the cost is reduced. And the desulfurization cost of the subsequent steelmaking procedure and the slag outward transportation cost are greatly reduced, and the working intensity of a stokehold is greatly reduced.

Description

Technical Field

[0001] The invention relates to a method for realizing smooth first iron tapping in a blast furnace. Background Art

[0002] One of the important tasks of blast furnace opening is to ensure that the slag of the first iron has good fluidity so that it can be discharged smoothly from the iron mouth and the slag and iron can be separated smoothly. Only when the above conditions are guaranteed can the blast furnace smelting process proceed smoothly and the subsequent strengthening measures can continue to be taken. The premise for achieving the above goals is that the heat in the lower part of the furnace is sufficient. However, in the process of opening the furnace, the furnace is filled with materials at room temperature. The temperature in the lower part of the furnace is much lower than the temperature in the normal production state, and it is also much lower than the temperature that can ensure the smooth flow of slag and iron. After the blast furnace is ignited, most of the high-temperature coal gas, the main source of heat income in the furnace in the early stage of opening the furnace, passes upward from the material column and is discharged from the upper part. Only a small part passes from the lower material column into the furnace to heat the furnace. The low heat income of the furnace makes it difficult for the furnace to be quickly heated in a short time, and it is difficult to provide heat conditions for improving the fluidity of slag and iron. If the furnace temperature is insufficient, it is easy to cause high [Si] and high [S] in pig iron, which will disrupt the production rhythm of subsequent steelmaking processes. In severe cases, it is difficult for slag iron to penetrate into the furnace, and it may even accumulate at the bottom and front end of the tuyere, causing extensive damage to the tuyere and affecting the entire furnace opening process. Summary of the invention

[0003] The purpose of the present invention is to provide a method for achieving smooth first iron tapping in a blast furnace, which can achieve smooth discharge of slag and iron and facilitate subsequent strengthening operations.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for achieving smooth first iron tapping of a blast furnace when the furnace is opened, comprising:

[0006] After the blast furnace is baked, small-sized dry coke is selected when loading the bottom coke. Small-sized dry coke has a larger specific surface area, which can enhance the heat exchange between the high-temperature coal gas and the bottom coke, and can achieve a rapid increase in the temperature of the bottom coke.

[0007] The total coke ratio of the starting charge is controlled at 3.3-3.5t / t, the basicity of the whole furnace is controlled at 0.9-0.95, and the basicity of the empty coke is controlled at 0.88-0.90;

[0008] Clean coke is loaded into the furnace belly, and empty coke is loaded into the furnace waist and the lower part of the furnace body to meet the slag-making requirements; limestone and silica are used to dilute the Al2O3 content in the slag to 12%-14%;

[0009] All sleepers are laid loose from the bottom coke to the center line of the tuyere, but sleepers are laid closely starting from 600mm from the center line of the tuyere, and the gap between closely laid sleepers is controlled to be less than 25mm;

[0010] Before supplying air, quickly open all the tapholes to increase the equivalent diameter of the lower gas channel, reduce the dead zone of the furnace gas flow, and place an open flame in front of the taphole to ignite the gas spewing out of the taphole. After the taphole starts to spew out slag, keep poking the taphole open to prevent slag from blocking the taphole, and try to extend the taphole slag spraying time;

[0011] After the air is supplied, the top vent valve is partially closed to increase the upward gas resistance, so as to increase the gas flow entering the furnace;

[0012] Set up sand dams in front of all main trench sand outlets, and only plug the outlets after the slag sprayed from the taphole fills the main trench in front of the temporary sand dam, thus extending the taphole slag spraying time;

[0013] Control the mud volume during the first plugging, add mud in batches, and increase the density of mud core in the iron mouth channel;

[0014] Pre-drill the taphole 1 hour before the set taphole opening time;

[0015] Control the cooling intensity of the furnace bottom, pass a small amount of water before supplying air, and gradually increase the cooling intensity after the load material is lowered into the furnace, so as to reduce the heat loss of the furnace.

[0016] Furthermore, small-size dry coke is coke cubes with a particle size of less than 25 mm, which are spread 1000 mm thick on the bottom of the furnace.

[0017] Furthermore, the sleeper density is 750-850kg / m 3 , the filling rate is 0.52-0.55.

[0018] Furthermore, the sleeper density is 800kg / m 3 .

[0019] Furthermore, the sleeper size is: 0.8-1.0m*0.2m*0.16m.

[0020] Furthermore, when plugging the iron mouth, 1 / 3 of the normal mud volume is injected for the first time. After 20 seconds, the mud injection pressure is further increased by 5%, and 1 / 5 of the mud volume is added to increase the density of the mud core in the iron mouth channel to prevent the first iron and the iron mouth from "running out of large amounts".

[0021] Furthermore, the cooling water volume of the blast furnace was controlled at 2000t / h and the inlet water temperature at 40℃ before air supply. After air supply, the water volume was increased to 4000t / h and the inlet water temperature was continued to be controlled at 40℃. The water volume was not increased and the inlet water temperature was not lowered before the first iron production, in order to reduce the heat loss of the furnace. After adopting the above measures, the iron mouth was opened smoothly at the scheduled time, 400t of iron was tapped, the slag iron had good fluidity, the first iron tapping slag had a PT of 1479℃.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] The present invention adopts a series of measures in the process of opening the blast furnace, such as controlling the particle size of the bottom coke, controlling the whole furnace coke ratio, slag R, optimizing the sleeper filling method, quickly opening the iron mouth after air supply to eliminate the furnace gas circulation dead zone, setting up the main ditch sand dam to extend the iron mouth slag spraying time, etc. The establishment of the above control points can effectively improve the heat exchange effect of the furnace and the gas, effectively increase the slag and iron temperature at the same whole furnace coke ratio in the early stage, make the molten iron [Si] low, [S] low, and the physical temperature is sufficient to make the slag and iron flow out smoothly, and the first iron can be flushed with water slag, which greatly reduces the desulfurization cost of the subsequent steelmaking process, the slag transportation cost, and the work intensity of the furnace workers. DETAILED DESCRIPTION

[0024] A method for achieving smooth first-time iron tapping in a blast furnace, comprising:

[0025] 1. When the blast furnace is finished and the charge is loaded, the coke for the bottom is selected after the coke powder is screened out, and the coke diced with a particle size of less than 25mm is spread on the bottom of the furnace with a thickness of 1000mm. The coke diced with smaller particle size can strengthen the heat exchange between the gas entering the furnace and the bottom coke, thereby increasing the temperature of the bottom coke under the conditions of the same gas volume and the same gas temperature.

[0026] 2. The coke ratio of the whole furnace is set at 3.5t / t. The R of the whole furnace is controlled at 0.94, and the basicity of empty coke is controlled at 0.9.

[0027] 3. Fill all the clean coke in the blast furnace belly, empty coke in the furnace waist, and 286m3 in the lower part of the furnace body. 3 Empty coke further raises the position of the loaded material, further slows down the time for a large amount of slag to reach the furnace, so that the upper loaded material can be fully heated; the Al2O3 content in the slag of the whole furnace charge is controlled at 12.3% by adding limestone + silica, and the Al2O3 content of the lower loaded material is controlled at 10.0%. The addition of limestone and silica is gradually and slowly reduced, so that the Al2O3 content gradually and slowly increases, and the maximum is controlled below 16.0%. This control method improves the fluidity of the first iron slag and reduces the iron ratio of the whole furnace slag, further reducing the heat loss of the furnace.

[0028] 4. After the bottom coke is loaded and leveled, a layer of short sleepers (sleeper size: 0.8-1.0m*0.2m*0.16m) is densely laid on the bottom coke, and then the short sleepers are filled in bulk. The short sleepers are arranged in a dense manner about 600mm from the tuyere. The use of smaller sleepers combined with the upper and lower dense laying method can increase the filling rate of the furnace and reduce the speed of the upper coke replacing the sleepers.

[0029] 5. Open all four iron mouths 30 minutes before air supply to reduce the lower resistance and the dead zone of gas flow in the furnace. Place a permanent gas fire in front of the iron mouth to monitor the unobstructed condition of the iron mouth. Clear it immediately if it is blocked by the ejected slag.

[0030] 6. Close one furnace top vent valve after air supply.

[0031] 7. The slag sprayed from the iron mouth accumulates in the main groove. When the slag surface is less than 10cm away from the lower edge of the iron mouth, the mouth should be blocked.

[0032] 8. When plugging the mouth, inject 1 / 3 of the normal mud volume for the first time. After 20 seconds, continue to increase the mud injection pressure by 5% and add 1 / 5 of the mud volume to increase the density of the mud core in the iron mouth channel to prevent the first iron and the iron mouth from "running out of large amounts".

[0033] 9. One hour before the scheduled tapping time, pre-opening operation should be carried out, and 1 / 2 of the tapping depth should be drilled in advance.

[0034] 10. Before air supply to the blast furnace, the cooling water volume is controlled at 2000t / h and the inlet water temperature is controlled at 40℃. After air supply, the water volume is increased to 4000t / h and the inlet water temperature continues to be controlled at 40℃. Before the first iron production, the water volume will not be increased and the inlet water temperature will not be lowered to reduce heat loss in the furnace.

[0035] After adopting the above measures, the taphole was opened smoothly at the scheduled time, 400t of iron was tapped, the slag iron had good fluidity, the first iron tapping was water slag, and the PT was 1479℃.

[0036] The present invention adopts a series of measures in the process of opening the blast furnace, such as controlling the particle size of the bottom coke, controlling the whole furnace coke ratio, slag R, optimizing the sleeper filling method, quickly opening the iron mouth after air supply to eliminate the furnace gas circulation dead zone, setting up the main ditch sand dam to extend the iron mouth slag spraying time, etc. The establishment of the above control points can effectively improve the heat exchange effect of the furnace and the gas, effectively increase the slag and iron temperature at the same whole furnace coke ratio in the early stage, make the molten iron [Si] low, [S] low, and the physical temperature is sufficient to make the slag and iron flow out smoothly, and the first iron can be flushed with water slag, which greatly reduces the desulfurization cost of the subsequent steelmaking process, the slag transportation cost, and the work intensity of the furnace workers.

[0037] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for achieving smooth first iron tapping in a blast furnace, characterized in that: include: After the blast furnace is baked, small-sized dry coke is selected when loading the bottom coke. Small-sized dry coke has a larger specific surface area, which can enhance the heat exchange between the high-temperature coal gas and the bottom coke, and can achieve a rapid increase in the temperature of the bottom coke. The total coke ratio of the starting charge is controlled at 3.3-3.5t / t, the basicity of the whole furnace is controlled at 0.9-0.95, and the basicity of the empty coke is controlled at 0.88-0.90; Clean coke is loaded into the furnace belly, and empty coke is loaded into the furnace waist and the lower part of the furnace body to meet the slag-making requirements; limestone and silica are used to dilute the Al2O3 content in the slag to 12%-14%; All sleepers are laid loose from the bottom coke to the center line of the tuyere, but sleepers are laid closely starting from 600mm from the center line of the tuyere, and the gap between closely laid sleepers is controlled to be less than 25mm; Before supplying air, quickly open all the tapholes to increase the equivalent diameter of the lower gas channel, reduce the dead zone of the furnace gas flow, and place an open flame in front of the taphole to ignite the gas spewing out of the taphole. After the taphole starts to spew out slag, keep poking the taphole open to prevent slag from blocking the taphole, and try to extend the taphole slag spraying time; After the air is supplied, the top vent valve is partially closed to increase the upward gas resistance, so as to increase the gas flow entering the furnace; Set up sand dams in front of all main trench sand outlets, and only plug the outlets after the slag sprayed from the taphole fills the main trench in front of the temporary sand dam, thus extending the taphole slag spraying time; Control the mud volume during the first plugging, add mud in batches, and increase the density of mud core in the iron mouth channel; Pre-drill the taphole 1 hour before the set taphole opening time; Control the cooling intensity of the furnace bottom, pass a small amount of water before supplying air, and gradually increase the cooling intensity after the load material is lowered into the furnace, so as to reduce the heat loss of the furnace.

2. The method for realizing smooth first iron tapping of a blast furnace according to claim 1, characterized in that: Small-size dry coke is coke cubes with a particle size of less than 25mm, which are spread 1000mm thick on the bottom of the furnace.

3. The method for realizing smooth first iron tapping of a blast furnace according to claim 1, characterized in that: Sleeper density is 750-850kg / m 3 , the filling rate is 0.52-0.

55.

4. The method for realizing smooth first iron tapping of a blast furnace according to claim 3, characterized in that: Sleeper density is 800kg / m 3 .

5. The method for realizing smooth first iron tapping of a blast furnace according to claim 1, characterized in that: Sleeper size: 0.8-1.0m*0.2m*0.16m.

6. The method for realizing smooth first iron tapping of a blast furnace according to claim 1, characterized in that: When plugging the iron mouth, inject 1 / 3 of the normal mud volume for the first time. After 20 seconds, continue to increase the mud injection pressure by 5% and add 1 / 5 of the mud volume to increase the density of the mud core in the iron mouth channel to prevent the first iron and the iron mouth from "running out of large amounts".

7. The method for realizing smooth first iron tapping of a blast furnace according to claim 1, characterized in that: Before air supply to the blast furnace, the cooling water volume was controlled at 2000t / h and the inlet water temperature was controlled at 40℃. After air supply, the water volume was increased to 4000t / h and the inlet water temperature was continued to be controlled at 40℃. Before the first iron production, the water volume was not increased and the inlet water temperature was not lowered to reduce the heat loss of the furnace. After adopting the above measures, the iron mouth was opened smoothly at the scheduled time, 400t of iron was tapped, the slag iron had good fluidity, the first iron tapping slag had a PT of 1479℃.