Method for controlling thickness of frozen layer at bottom of top-blown furnace

Abstract

The invention discloses a method for controlling the thickness of a frozen layer at the bottom of a top-blown furnace, and belongs to the technical field of copper smelting of the top-blown furnace. The method specifically comprises the following steps: (1) feeding a sampling rod into the top-blown furnace from the top of the furnace, detecting the condition of a frozen layer at the bottom of the furnace, and under the condition that the thickness of the frozen layer at the bottom of the top-blown furnace is less than 50mm, (11) strongly oxidizing slag; (12) separating out magnetic iron oxide to form a new freezing layer; (2) feeding a sampling rod into the top-blown furnace from the top of the furnace, detecting the condition of a freezing layer at the bottom of the furnace, and under the condition that the thickness of the freezing layer at the bottom of the top-blown furnace is greater than 100mm, (21) quickly heating the furnace slag; (22) a furnace bottom freezing layer is stirred open; (23) reducing the slag to obtain crude copper to replace magnetic iron oxide; and (24) furnace slag feeding and re-reduction. According to the method, the thickness of the frozen layer at the bottom of the top-blown furnace can be controlled within a reasonable range, normal operation of copper port burning and crude copper discharging is guaranteed while the refractory material at the bottom of the furnace is protected, and the production benefit is improved.

Description

Technical Field

[0001] This invention relates to the field of top-blown furnace copper smelting technology, and more specifically to a method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace. Background Technology

[0002] Currently, the pyrometallurgical process for copper sulfide concentrate is as follows: copper concentrate smelting to produce copper matte → copper matte blowing to produce blister copper → blister copper pyrometallurgical refining to produce anode copper → electrolysis to produce cathode copper (Cu>99.95%). Equipment used for blowing copper matte into blister copper includes PS converters, flash furnaces, top-blown furnaces, continuous-blown reverberatory furnaces, and Mitsubishi continuous-blown furnaces. Regardless of the blowing method used, smelting slag is produced along with blister copper.

[0003] Top-blown copper smelting utilizes a top-blown lance inserted into the molten pool from the top of the furnace. The lance provides air and oxygen enrichment, while copper matte, reducing coal, and flux are added from the top, resulting in a solid-liquid-gas three-phase reaction that produces crude copper and smelting slag. The molten pool is under intense agitation when the lance is inserted, providing excellent kinetic conditions and increasing the blowing rate and production efficiency of the top-blown furnace. However, the strong oxygen potential within the furnace leads to an increase in magnetic iron oxide in the slag, typically ranging from 20% to 50% (Fe3O4) and 18% to 25% (copper). Towards the end of the copper tapping process, the highly magnetic slag comes into contact with the cooler furnace bottom, causing the magnetic iron oxide (Fe3O4) phase to precipitate out and form a thick, frozen layer at the furnace bottom. The presence of a frozen layer at the furnace bottom has both advantages and disadvantages. Its advantage lies in providing a protective layer for the furnace bottom refractory material, shielding it from the scouring and erosion of the high-temperature molten metal. Its disadvantage is that when the frozen layer accumulates to a certain thickness, in mild cases the copper opening is small, resulting in a longer time for discharging blister copper; in severe cases, the copper opening takes longer to open, or even fails to open, affecting blister copper discharge, significantly restricting the start-up time of the top-blown furnace, and impacting the copper matte processing capacity of the top-blown furnace. Therefore, in production, the thickness of the frozen layer at the furnace bottom is controlled at approximately 50-100 mm.

[0004] Therefore, how to develop a method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace, so as to solve the problems in the prior art where the thickness of the frozen layer at the bottom of the furnace is too low or too high during the copper smelting process in a top-blown furnace, resulting in severe damage to the refractory material at the bottom of the furnace or a long firing time or even failure to fire the crude copper inlet and a long time for discharging crude copper.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace specifically includes the following steps: (1) Lower the sampling rod into the top-blown furnace from the top to detect the condition of the frozen layer at the bottom of the furnace. If the thickness of the frozen layer at the bottom of the top-blown furnace is <50mm: (11) Strong oxidation of slag After the copper production period in the top-blown furnace is completed, the spray gun is raised to 200mm below the slag layer. The feed rate and coefficient of reducing coal are adjusted to carry out strong oxidation, so that highly magnetic iron slag is generated in the slag and sinks to the surface of the copper layer. The spray gun is then removed for subsequent discharge operations. (12) Magnetic iron oxide (Fe3O4) precipitates to form a new frozen layer. After removing the spray gun, increase the flow rate of the furnace bottom steel shell cooling water. In addition to the existing cooling water for the furnace bottom sides, install four axial flow fans to air-cool the bottom surface of the furnace. When discharging crude copper, do not immediately plug the copper outlet after discharging the copper. Instead, discharge some slag before plugging, so that the highly magnetic iron slag on the copper layer can come into contact with the cooler furnace bottom, precipitating magnetic iron oxide to form a new frozen layer, thereby increasing the thickness of the frozen layer at the bottom of the top-blown furnace. Perform this operation for each furnace cycle to continuously generate a new frozen layer at the bottom of the furnace. When the sampling rod detects that the frozen layer thickness is 75mm, reduce the flow rate of the furnace bottom steel shell cooling water to the normal flow rate and turn off the axial flow fans. (2) Insert the sampling rod into the top-blown furnace from the top to detect the condition of the frozen layer at the bottom of the furnace. If the thickness of the frozen layer at the bottom of the top-blown furnace is >100mm: (21) Rapid heating of slag When the top-blown furnace enters the crude copper discharge stage, the axial flow fan is turned off and the cooling water flow rate of the furnace bottom steel shell is reduced. At the end of the crude copper discharge stage, the sampling rod is lowered to detect the height of the molten pool and the thickness of the frozen layer at the bottom of the furnace. The new spray gun is lowered 200mm below the slag layer in the furnace, and the reducing coal feed rate and reducing coal coefficient are adjusted to rapidly heat the slag. After heating, the spray gun is raised above the surface of the molten pool to prevent slag "foaming". During the later process of lowering the gun, the molten pool will drop due to the crude copper discharge stage, so the gun position must be lowered. The slag temperature is raised by adding a large amount of reducing coal. This cycle continues until the crude copper discharge is completed. (22) Stir up the frozen layer at the bottom of the furnace. After the crude copper discharge is completed, insert the spray gun head 300mm above the frozen layer at the bottom of the furnace, adjust the reducing coal feed rate and reducing coal coefficient, and use the stirring effect of the spray gun air to stir the magnetic iron oxide phase and highly magnetic slag in the frozen layer at the bottom of the furnace, so that the magnetic iron oxide phase at the bottom of the frozen layer and the highly magnetic iron slag at the top of the frozen layer are mixed with the slag, and continue to heat the slag. During the stirring process, use a sampling rod to detect the thickness of the frozen layer. When the thickness of the frozen layer at the bottom of the furnace reaches 75mm, this step is ended. (23) Slag is reduced to crude copper to replace magnetic iron oxide After the frozen layer at the bottom of the furnace is fully stirred up, raise the position of the spray gun to 200mm below the slag layer in the furnace; adjust the feeding speed and reducing coal coefficient to allow the mechanically mixed Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide that precipitates out of the slag due to the low temperature at the bottom of the furnace. This achieves the goal of keeping the copper in a liquid state at the bottom while isolating the highly magnetic iron slag from contact with the bottom of the furnace, thereby reducing the frozen layer. (24) Slag feeding and re-reduction Once the slag in the top-blown furnace has been reduced, upstream and downstream processes can be contacted and copper matte can be added to enter the slag-forming period. The copper matte feed rate and smelting coefficient, the reducing coal feed rate and reducing coal coefficient can be adjusted to reduce the magnetic iron oxide content in the slag and reduce the frozen layer. When the copper matte feed rate reaches 10t, the feed rate can be increased, the smelting excess coefficient can be increased, the axial flow fan can be kept off, the cooling water flow rate of the furnace bottom steel shell can be increased, and normal operation can begin.

[0007] The method of this invention involves strong oxidation of the slag at the end of the copper-making period, generating more highly magnetic iron slag that settles to the surface of the molten copper layer and eventually precipitates at the lower temperature of the furnace bottom, forming a frozen layer. Alternatively, the slag at the end of the crude copper discharge stage is rapidly heated, controlling the slag temperature to 1280-1300℃. After the crude copper discharge is completed, the frozen layer at the furnace bottom is stirred and mixed with the slag. Reducing coal and copper matte with a low conversion rate in the initial feeding stage are used to reduce the magnetic iron oxide (Fe3O4) and Cu2O phases in the blowing slag, improving the viscosity and fluidity of the slag. This causes mechanically incorporated Cu and chemically dissolved Cu2O to precipitate from the slag, replacing the magnetic iron oxide (Fe3O4) that precipitates from the slag due to the lower furnace bottom temperature. This isolates the highly magnetic iron slag from contact with the furnace bottom, reducing the frozen layer at the furnace bottom. The main reactions are as follows: C + O₂ = CO₂; 6FeO + O2 = 2Fe3O4; 2C + O2 = 2CO; 2CO + O2 = 2CO2; 2Fe3O4 + C = 6FeO + CO2; Fe3O4+Cu2S+O2=3FeO+Cu2O+SO2; 2FeO + SiO2 = 2FeO·SiO2; 2Cu₂S + 3O₂ = 2Cu₂O + 2SO₂; Cu₂S + 2Cu₂O = 6Cu + SO₂; 2FeS + 3O2 = 2FeO + 2SO2.

[0008] Due to the presence of the above reactions, the formation and reduction of magnetic iron oxide (Fe3O4) in the high magnetic iron slag can be controlled, the contact between the high magnetic iron slag and the furnace bottom can be controlled, thereby controlling the thickness of the frozen layer at the bottom of the top-blown furnace.

[0009] This invention, based on the varying thickness of the frozen layer at the bottom of a top-blown furnace, adds four axial flow fans to the existing furnace bottom cooling system, which uses cooling water to cool the sides of the furnace bottom. High-magnetic iron slag, upon contact with the cooler furnace bottom, precipitates magnetic iron oxide (Fe3O4), forming a new frozen layer, thus increasing the thickness of the frozen layer. Alternatively, a spray gun head can be inserted into the frozen layer at the bottom, rapidly heating it while simultaneously stirring the surface of the frozen layer. This mixes the high-magnetic iron slag with the slag, reducing the magnetic iron oxide (Fe3O4) in the blowing slag to FeO. This causes mechanically incorporated Cu and chemically dissolved Cu2O to precipitate from the slag, replacing the magnetic iron oxide (Fe3O4) precipitated at the furnace bottom. This process keeps copper in a liquid state at the bottom while isolating the high-magnetic iron slag from contact with the furnace bottom, thereby reducing the thickness of the frozen layer. This invention can control the thickness of the frozen layer at the bottom of the top-blown furnace within a reasonable range, protecting the refractory material at the bottom of the furnace while ensuring the normal operation of the copper firing port and the discharge of crude copper, thereby improving production efficiency.

[0010] Furthermore, in steps (1) and (2) above, the sampling rod is 15.7m long and 70mm in diameter. Its length is consistent with the height of the furnace. It is lowered into the top-blown furnace. The length of the sampling rod protruding from the top of the furnace is the thickness of the frozen layer at the bottom of the furnace.

[0011] Furthermore, in the above step (11), the back pressure of the spray gun is above 50 kPa; the fixed carbon content of the reducing coal is >60%, the particle size of the lump coal is 10-15 mm, and the Cu content of the copper matte is 59%-63%; the specific adjustment of the reducing coal feed rate and reducing coal coefficient is as follows: control the reducing feed rate to 1.5 t / h coal, control the combustion coefficient of the reducing coal to 7000 Nm = t, and the excess coefficient of the reducing coal to 120%; the strong oxidation time is 6 min.

[0012] Furthermore, in step (12) above, the flow rate of the cooling water for the furnace bottom steel shell is increased to 130% of the normal flow rate; the axial flow fan has a diameter of 615mm, a power of 2200W, and an air volume of 18700m³. 3 / h of the stationary axial flow fan; reduce the flow rate of the cooling water for the furnace bottom steel shell to the normal flow rate.

[0013] The further beneficial effect of adopting the above-mentioned methods is that when the thickness of the frozen layer at the furnace bottom is <50mm, the formation of the frozen layer can be promoted by increasing the flow rate of the cooling water for the furnace bottom steel shell and increasing the cooling of the furnace bottom by the axial flow fan. When the thickness of the frozen layer at the furnace bottom is >100mm, the thickness of the frozen layer can be reduced by decreasing the flow rate of the cooling water for the furnace bottom steel shell and turning off the axial flow fan.

[0014] Furthermore, in step (21) above, the flow rate of the cooling water in the furnace bottom steel shell is reduced to 70% of the normal flow rate; the back pressure of the spray gun is above 45 kPa; the specific adjustments to the reducing coal feed rate and reducing coal coefficient are as follows: the reducing coal feed rate is controlled at 2.5 t / h, and the reducing coal combustion coefficient is controlled at 6600 Nm. 3 / t, the excess coefficient of reducing coal is 85%; the heating time is 6min; the spray gun is raised above the surface of the molten pool for 3min; the temperature is raised to 1280-1300℃.

[0015] Furthermore, in step (22) above, adjusting the reducing coal feed rate and reducing coal coefficient specifically involves controlling the reducing coal feed rate to 2.5 t / h and controlling the reducing coal combustion coefficient to 6600 Nm. 3 / t, with a reduced coal surplus coefficient of 85%.

[0016] Furthermore, in step (23) above, the back pressure of the spray gun is above 35 kPa; the adjustment of the reducing coal feed rate and reducing coal coefficient is specifically as follows: control the reducing coal feed rate to 4.5 t / h, and control the reducing coal combustion coefficient to 3000 Nm. 3 / t, the excess coefficient of reducing coal is 85%; the reduction time is 6min, and the reduction endpoint is determined by the CO content in the flue gas of the blowing furnace, when the CO content in the flue gas reaches 1000-1200ppm.

[0017] The further beneficial effect of the above-mentioned method is that, after adjusting the reducing coal feed rate and reducing coal coefficient, the combustion coefficient of the reducing coal decreases, and the air distribution is significantly reduced, which will generate a large amount of carbon monoxide gas. This gas will reduce the magnetic iron oxide (Fe3O4) phase in the slag to FeO, improving the viscosity and fluidity of the slag. This will cause mechanically incorporated Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide (Fe3O4) that precipitates out of the slag due to the low furnace bottom temperature. Because copper has a low melting point and high specific gravity, it is possible to keep copper in a liquid state at the bottom while isolating the highly magnetic iron slag from contact with the furnace bottom, thereby reducing the frozen layer.

[0018] Furthermore, in step (24) above, adjusting the copper matte feed rate and smelting coefficient specifically involves controlling the copper matte feed rate to 30-35 t / h and the smelting coefficient to 800 Nm. 3 / t, smelting excess coefficient 85%; the specific adjustments to the reducing coal feed rate and reducing coal coefficient are as follows: control the reducing coal feed rate at 3t / h, and the reducing coal combustion coefficient at 6600Nm. 3 / t, the excess coefficient of reducing coal is 70%; the flow rate of cooling water in the furnace bottom steel shell is increased to the normal flow rate.

[0019] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: 1. After the copper production period in the top-blown furnace is completed, reducing coal is introduced into the molten pool through the lifting lance. Excessive air is then blown into the molten pool through the lance to strongly oxidize the slag, causing highly magnetic iron slag to be generated in the slag and sink to the surface of the copper layer.

[0020] 2. Increase the flow rate of the furnace bottom steel shell cooling water. In addition to the existing cooling water for the furnace bottom sides, install four axial flow fans to provide air cooling for the bottom surface of the furnace bottom. When discharging crude copper, discharge some slag after the copper is discharged before plugging the copper outlet. This allows the highly magnetic iron slag on the copper layer to come into contact with the cooler furnace bottom, precipitating magnetic iron oxide (Fe3O4) to form a new frozen layer, thereby increasing the thickness of the frozen layer at the bottom of the top-blown furnace.

[0021] 3. At the end of the crude copper discharge stage, reducer coal is added to the lower spray gun in advance. Sufficient air is blown into the molten pool through the spray gun, and the reducer coal burns rapidly, causing the slag to heat up quickly, in preparation for subsequent steps.

[0022] 4. Utilize the stirring effect of the spray gun air to break up the magnetic iron oxide (Fe3O4) phase and highly magnetic slag in the frozen layer at the bottom of the furnace, so that the magnetic iron oxide (Fe3O4) phase at the bottom of the frozen layer and the highly magnetic iron slag at the top of the frozen layer are mixed with the slag, and the slag is heated up.

[0023] 5. By reducing the combustion coefficient of reducing coal, a large amount of carbon monoxide gas is generated, and the magnetic iron oxide (Fe3O4) phase in the blowing slag is reduced to FeO, improving the viscosity and fluidity of the slag. This causes mechanically incorporated Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide (Fe3O4) that precipitates out of the slag due to the low temperature at the bottom of the furnace. This allows copper to remain in a liquid state at the bottom while isolating the highly magnetic iron slag from contact with the furnace bottom, thereby reducing the frozen layer.

[0024] 6. By using a small amount of material and a low conversion rate in the initial feeding stage, the FeS in the copper matte does not have enough air to be converted into FeO. This causes some of the FeS to undergo a reduction reaction with the residual magnetic iron oxide (Fe3O4) phase in the smelting slag to generate FeO, reducing the magnetic iron content in the slag. At the same time, the Cu2S in the copper matte will also react with the residual Cu2O in the slag to generate copper, which will settle at the bottom. This prevents the high magnetic iron slag from precipitating magnetic iron oxide (Fe3O4) at the bottom of the furnace, thereby reducing the frozen layer.

[0025] 7. The method of the present invention produces highly magnetic iron slag by performing strong oxidation on the slag. The resulting strong stirring causes the slag with high magnetic iron content to splash onto the furnace wall and spray gun to form a slag protective layer, which protects the furnace bricks and spray gun.

[0026] 8. The method of the present invention involves inserting the nozzle of the spray gun near the frozen layer at the bottom of the furnace, mixing the high magnetic iron slag at the bottom of the furnace with the middle and upper layers of slag. In addition, the large insertion depth of the spray gun and the large air volume generate strong agitation, causing the slag with high magnetic iron content to splash onto the furnace wall and the spray gun to form a slag-coated protective layer, which protects the furnace bricks and the spray gun. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the top-blown furnace used in the method of the present invention; wherein, 1-spray gun, 2-spray gun duct, 3-spray gun oxygen port, 4-feed inlet, 5-burner port, 6-sampling rod, 7-rising flue, 8-slag blowing port, 9-copper port, 10-top-blown furnace bottom, 11-axial flow fan, 12-furnace bottom steel shell cooling water jacket, 13-furnace bottom freezing layer, 14-slag blowing layer, 15-top-blown furnace flue gas zone, 16-freezing layer thickness; Figure 2 This is a structural schematic diagram of the thickness of the furnace bottom freezing layer in the method of the present invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1 A top-blown furnace with a diameter of 5m × H15.7m and a copper inlet diameter of 50mm (such as...) Figure 1-2 As shown in the figure, the recent copper tapping time is 10 minutes, the crude copper discharge time is 60 minutes, the copper water jacket plate temperature at the crude copper discharge port is 50-70℃, and after the crude copper discharge is completed, the sampling rod is used to measure the thickness of the frozen layer at the bottom of the furnace, which is 80mm. It is determined that the thickness of the frozen layer at the bottom of the furnace is normal, and the top blowing furnace operation is carried out according to normal operation.

[0030] Example 2 A top-blown furnace with a diameter of 5m × H15.7m and a copper inlet diameter of 50mm (such as...) Figure 1-2 As shown in the figure, the recent copper tapping time was 5 minutes, the crude copper discharge time was 45 minutes, and the temperature of the copper plate in the copper water jacket at the crude copper discharge port was 80-90℃. After the crude copper discharge was completed, the thickness of the frozen layer at the bottom of the furnace was measured by the sampling rod to be 30mm. It was determined that the thickness of the frozen layer at the bottom of the furnace had become too thin. The following operations were taken to adjust it: (1) Strong oxidation of slag After the copper production period in the top-blown furnace is completed, the spray gun is raised to 200mm below the slag layer, and 1.5t / h of reducing coal is introduced, controlling the combustion coefficient of the reducing coal to 7000Nm. 3 / t, with a reducing coal excess coefficient of 120%, the slag undergoes strong oxidation, and the total air volume supplied into the furnace is 12600 Nm³. 3 / h, due to the burn-out and blockage of the spray gun after the copper production period, the back pressure of the spray gun is higher than that of the normal spray gun, reaching 51Kpa. Due to the high combustion coefficient of the reducing coal and the large air volume, the high magnetic iron slag generated in the slag sinks to the surface of the copper layer. The strong oxidation time is controlled within 6 minutes before the spray gun can be removed for subsequent discharge operations. (2) Magnetic iron oxide (Fe3O4) precipitates to form a new frozen layer. After removing the spray gun, the flow rate of the furnace bottom steel shell cooling water was increased to 130% of the normal flow rate. In addition to the existing cooling water for the furnace bottom sides, four axial flow fans were added to provide air cooling for the bottom surface of the furnace bottom. When discharging crude copper, the copper outlet was not immediately blocked after discharge. Instead, some slag was discharged before blocking, allowing the highly magnetic iron slag on the copper layer to come into contact with the cooler furnace bottom, precipitating magnetic iron oxide (Fe3O4) to form a new frozen layer, thereby increasing the thickness of the frozen layer at the bottom of the top-blown furnace. Following this method, the frozen layer thickness was measured to be 75 mm after three consecutive furnace cycles. The flow rate of the furnace bottom steel shell cooling water was then reduced to the normal flow rate, the axial flow fans were turned off, and the method of generating a new frozen layer was terminated. The top-blown furnace operation was then carried out normally.

[0031] Example 3 A top-blown furnace with a diameter of 5m × H15.7m and a copper inlet diameter of 50mm (such as...) Figure 1-2 As shown in the figure, the recent copper tapping time was 20 minutes, the crude copper discharge time was 80 minutes, and the copper plate temperature of the copper water jacket at the crude copper discharge port was 40-50℃. After the crude copper discharge was completed, the thickness of the frozen layer at the bottom of the furnace was measured by the sampling rod to be 110mm. It was determined that the frozen layer at the bottom of the furnace had thickened, and the following operations were taken to control it: (1) Rapid heating of slag After 30 minutes of top-blown furnace effluent discharge of crude copper, the axial flow fan was shut off, and the flow rate of the furnace bottom cooling water was reduced to 70% of the normal flow rate. The sampling rod was lowered, and the molten pool height was measured to be 1200 mm, and the thickness of the frozen layer at the furnace bottom was measured to be 110 mm. The new spray lance was lowered to 1000 mm, and simultaneously, 2.5 t / h of reducing coal was added, controlling the combustion coefficient of the reducing coal to be 6600 Nm³. 3 / t, with an excess reducing coal coefficient of 85%, the slag is rapidly heated; at this time, the total air volume supplied into the furnace is 14025 Nm³. 3 / h, the back pressure of the spray gun reaches 46Kpa; after heating for 6 minutes, the spray gun is lifted above the surface of the molten pool for 3 minutes to prevent the slag from "foaming". After 3 minutes, the process of lowering the gun and heating is repeated. The position of the gun is determined by the back pressure of the spray gun reaching 45Kpa. This cycle continues until the discharge of crude copper is finished, and the slag temperature has reached 1295℃. (2) Stir up the frozen layer at the bottom of the furnace. After the crude copper discharge is complete, lower the spray gun to 410mm and simultaneously add 2.5t / h of reducing coal, controlling the combustion coefficient of the reducing coal to 6600Nm³ / t and the excess reducing coal coefficient to 85%; at this point, the total air volume supplied into the furnace is 14025Nm³. 3 / h, the back pressure of the spray gun reaches 62Kpa; the stirring effect of the spray gun air is used to stir the magnetic iron oxide (Fe3O4) phase and the highly magnetic slag in the frozen layer at the bottom of the furnace, so that the magnetic iron oxide (Fe3O4) phase at the bottom of the frozen layer and the highly magnetic iron slag at the top of the frozen layer are mixed with the slag, and the slag is heated up; after stirring for 6 minutes, the spray gun is lifted above the surface of the molten pool for 3 minutes to prevent the slag from "foaming". After 3 minutes, the spray gun is lowered to stir the frozen layer at the bottom of the furnace again. During the process, the sampling rod is lowered to detect the thickness of the frozen layer at the bottom of the furnace. After stirring for a total of 10 minutes, the thickness of the frozen layer at the bottom of the furnace is detected to be 75mm. This step is completed; (3) Slag is reduced to crude copper to replace magnetic iron oxide After the frozen layer at the bottom of the furnace is fully stirred, the lance position is raised to 780mm, and 4.5t / h of reducing coal is fed in simultaneously, controlling the combustion coefficient of the reducing coal to 3000Nm. 3 / t, reducing coal excess coefficient 85%; at this time, the total air volume supplied into the furnace is 11475 Nm³. 3 / h, the back pressure reaches 36Kpa; due to the decrease in the combustion coefficient of the reducing coal at this time, the air distribution is greatly reduced, and a large amount of carbon monoxide gas will be generated to reduce the magnetic iron oxide (Fe3O4) phase in the slag to FeO, improve the viscosity and fluidity of the slag, and cause the mechanically incorporated Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide (Fe3O4) that precipitates out of the slag due to the low temperature of the furnace bottom. Since copper has a low melting point and high specific gravity, it can be achieved that copper remains in a liquid state at the bottom while isolating the high magnetic iron slag from contact with the furnace bottom, thereby reducing the frozen layer; after 6 minutes of reduction, the CO content in the flue gas reaches 1030ppm, reaching the end of the reduction; (4) Slag feeding and re-reduction After the slag reduction in the top-blown furnace is completed, the upstream and downstream processes are coordinated, and copper matte is introduced to enter the slag-forming period. The feed rate is maintained at a small amount of copper matte at 30 t / h, and the smelting coefficient is 800 Nm. 3 / t, smelting excess coefficient 85%, reducing coal 3t / h, reducing coal combustion coefficient 6600Nm 3 / t, reducing coal excess coefficient 70%; at this time, the total air volume supplied into the furnace is 16500 Nm³. 3 / h, oxygen supply is 3730 Nm³ 3The oxygen concentration was 35.5% and the back pressure was 62 kPa. This was used to control the conversion rate, ensuring that FeS in the copper matte did not have sufficient air to convert to FeO. Consequently, some FeS reacted with the residual magnetic iron oxide (Fe3O4) phase in the slag to form FeO, reducing the magnetic iron content in the slag. Simultaneously, Cu2S in the copper matte reacted with the residual Cu2O in the slag to form Cu, which settled at the bottom, preventing the precipitation of magnetic iron oxide (Fe3O4) in the high-magnetic-iron slag at the furnace bottom, thus reducing the frozen layer. When the copper matte feed reached 10t, the feed rate was increased, and the smelting excess coefficient was increased. At this point, the sampling rod was lowered, and the thickness of the frozen layer at the furnace bottom was detected to be 70mm. The axial flow fan was kept off, and the cooling water flow rate of the furnace bottom steel shell was increased to the normal flow rate. This method of reducing the frozen layer was then terminated, and the top-blown furnace operation proceeded as normal.

[0032] Example 4 A top-blown furnace with a diameter of 5m × H15.7mm and a copper inlet diameter of 50mm (such as...) Figure 1-2 As shown in the figure, the recent copper tapping time was 35 minutes, the crude copper discharge time was 100 minutes, and the copper plate temperature of the copper water jacket at the crude copper discharge port was 40-45℃. After the crude copper discharge was completed, the thickness of the frozen layer at the bottom of the furnace was measured by the sample rod to be 130 mm. It was determined that the frozen layer at the bottom of the furnace had thickened, and the following operations were taken to control it: (1) Rapid slag removal After the top-blown furnace discharged crude copper for 20 minutes, the axial flow fan was turned off, and the cooling water flow rate of the furnace bottom steel shell was reduced to 70% of the normal flow rate. The sampling rod was lowered, and the height of the molten pool was measured to be 1380 mm, and the thickness of the frozen layer at the furnace bottom was measured to be 130 mm. The new spray lance was lowered to 1180 mm, and 2.5 t / h of reducing coal was simultaneously added, controlling the combustion coefficient of the reducing coal to 6600 Nm³. 3 / t, with an excess reducing coal coefficient of 85%, the slag is rapidly heated; at this time, the total air volume supplied into the furnace is 14025 Nm³. 3 / h, the back pressure of the spray gun reaches 45Kpa; after heating for 6 minutes, the spray gun is lifted above the surface of the molten pool for 3 minutes to prevent the slag from "foaming". After 3 minutes, the process of lowering the gun and heating is repeated. The position of the gun is determined by the back pressure of the spray gun reaching 45Kpa. This cycle continues until the discharge of crude copper is finished, and the slag temperature has risen to 1300℃. (2) Stir up the frozen layer at the bottom of the furnace. After the crude copper discharge is complete, lower the spray gun to 430mm and simultaneously add 2.5t / h of reducing coal, controlling the combustion coefficient of the reducing coal to 6600Nm. 3 / t, reducing coal excess coefficient 85%; at this time, the total air volume supplied into the furnace is 14025 Nm³. 3 / h, the back pressure of the spray gun reaches 61Kpa; the stirring effect of the spray gun air is used to stir the magnetic iron oxide (Fe3O4) phase and the highly magnetic slag in the frozen layer at the bottom of the furnace, so that the magnetic iron oxide (Fe3O4) phase at the bottom of the frozen layer and the highly magnetic iron slag at the top of the frozen layer are mixed with the slag, and the slag is heated up; after stirring for 6 minutes, the spray gun is lifted above the surface of the molten pool for 3 minutes to prevent the slag from "foaming". After 3 minutes, the spray gun is lowered to stir the frozen layer at the bottom of the furnace again. During the process, the sampling rod is lowered to detect the thickness of the frozen layer at the bottom of the furnace. After stirring for a total of 25 minutes, the thickness of the frozen layer at the bottom of the furnace is detected to be 75mm. This step is completed; (3) Slag is reduced to crude copper to replace magnetic iron oxide After the frozen layer at the bottom of the furnace is fully stirred, the nozzle position is raised to 850mm, and 4.5t / h of reducing coal is fed in simultaneously, controlling the combustion coefficient of the reducing coal to 3000Nm. 3 / t, reducing coal excess coefficient 85%; at this time, the total air volume supplied into the furnace is 11475 Nm³. 3 / h, back pressure reaches 35Kpa; due to the decrease in the combustion coefficient of the reducing coal at this time, the air distribution is greatly reduced, and a large amount of carbon monoxide gas will be generated to reduce the magnetic iron oxide (Fe3O4) phase in the slag to FeO, improve the viscosity and fluidity of the slag, and cause the mechanically incorporated Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide (Fe3O4) that precipitates out of the slag due to the low temperature of the furnace bottom. Since copper has a low melting point and high specific gravity, it can be achieved that copper remains in a liquid state at the bottom while isolating the high magnetic iron slag from contact with the furnace bottom, thereby reducing the frozen layer; after 7 minutes of reduction, the CO content in the flue gas reaches 1080ppm, reaching the reduction endpoint; (4) Slag feeding and re-reduction After the slag reduction in the top-blown furnace is completed, the upstream and downstream processes are coordinated, and copper matte is introduced to enter the slag-forming period. The feed rate is maintained at a small amount of copper matte at 35 t / h, and the smelting coefficient is 800 Nm. 3 / t, smelting excess coefficient 85%, reducing coal 3t / h, reducing coal combustion coefficient 6600Nm 3 / t, reducing coal excess coefficient 70%; at this time, the total air volume supplied into the furnace is 16000 Nm³ / h, and the oxygen volume is 4548 Nm³ / h. 3The oxygen concentration was 38.1% and the back pressure was 66 kPa. This was used to control the conversion rate, ensuring that FeS in the copper matte did not have enough air to convert to FeO. Consequently, some FeS reacted with the residual magnetic iron oxide (Fe3O4) phase in the smelting slag to generate FeO, reducing the magnetic iron content in the slag. Simultaneously, Cu2S in the copper matte reacted with the residual Cu2O in the slag to form Cu, which settled at the bottom, preventing the precipitation of magnetic iron oxide (Fe3O4) in the high-magnetic-iron slag at the furnace bottom, thus reducing the frozen layer. When the copper matte feed reached 10t, the feed rate was increased, and the smelting excess coefficient was increased. At this point, the sampling rod was lowered, and the thickness of the frozen layer at the furnace bottom was detected to be 65mm. The axial flow fan was kept off, and the flow rate of the cooling water in the furnace bottom steel shell was increased to the normal flow rate. This method of reducing the frozen layer was then terminated, and the top-blown furnace operation was carried out normally.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace, characterized in that, Specifically, the following steps are included: (1) Lower the sampling rod into the top-blown furnace from the top to detect the condition of the frozen layer at the bottom of the furnace. If the thickness of the frozen layer at the bottom of the top-blown furnace is <50mm: (11) Strong oxidation of slag After the copper production period in the top-blown furnace is completed, the spray gun is raised to 200mm below the slag layer. The feed rate and coefficient of reducing coal are adjusted to carry out strong oxidation, so that highly magnetic iron slag is generated in the slag and sinks to the surface of the copper layer. The spray gun is then removed for subsequent discharge operations. (12) Magnetic iron oxide precipitates to form a new frozen layer. After removing the spray gun, increase the flow rate of the furnace bottom steel shell cooling water. In addition to the existing cooling water for the furnace bottom sides, install four axial flow fans to air-cool the bottom surface of the furnace. When discharging crude copper, do not immediately plug the copper outlet after discharging the copper. Instead, discharge some slag before plugging, so that the highly magnetic iron slag on the copper layer can come into contact with the cooler furnace bottom, precipitating magnetic iron oxide to form a new frozen layer, thereby increasing the thickness of the frozen layer at the bottom of the top-blown furnace. Perform this operation for each furnace cycle to continuously generate a new frozen layer at the bottom of the furnace. When the sampling rod detects that the frozen layer thickness is 75mm, reduce the flow rate of the furnace bottom steel shell cooling water to the normal flow rate and turn off the axial flow fans. (2) Insert the sampling rod into the top-blown furnace from the top to detect the condition of the frozen layer at the bottom of the furnace. If the thickness of the frozen layer at the bottom of the top-blown furnace is >100mm: (21) Rapid heating of slag When the top-blown furnace enters the crude copper discharge stage, the axial flow fan is turned off and the cooling water flow rate of the furnace bottom steel shell is reduced. At the end of the crude copper discharge stage, the sampling rod is lowered to detect the height of the molten pool and the thickness of the frozen layer at the bottom of the furnace. The new spray gun is lowered 200mm below the slag layer in the furnace, and the reducing coal feed rate and reducing coal coefficient are adjusted to rapidly heat the slag. After heating, the spray gun is raised above the surface of the molten pool to prevent slag "foaming". During the later process of lowering the gun, the molten pool will drop due to the crude copper discharge stage, so the gun position must be lowered. The slag temperature is raised by adding a large amount of reducing coal. This cycle continues until the crude copper discharge is completed. (22) Stir up the frozen layer at the bottom of the furnace. After the crude copper discharge is completed, insert the spray gun head 300mm above the frozen layer at the bottom of the furnace, adjust the reducing coal feed rate and reducing coal coefficient, and use the stirring effect of the spray gun air to stir the magnetic iron oxide phase and highly magnetic slag in the frozen layer at the bottom of the furnace, so that the magnetic iron oxide phase at the bottom of the frozen layer and the highly magnetic iron slag at the top of the frozen layer are mixed with the slag, and continue to heat the slag. During the stirring process, use a sampling rod to detect the thickness of the frozen layer. When the thickness of the frozen layer at the bottom of the furnace reaches 75mm, this step is ended. (23) Slag is reduced to crude copper to replace magnetic iron oxide After the frozen layer at the bottom of the furnace is fully stirred up, raise the position of the spray gun to 200mm below the slag layer in the furnace; adjust the feeding speed and reducing coal coefficient to allow the mechanically mixed Cu and chemically dissolved Cu2O in the slag to precipitate out of the slag, replacing the magnetic iron oxide that precipitates out of the slag due to the low temperature at the bottom of the furnace. This achieves the goal of keeping the copper in a liquid state at the bottom while isolating the highly magnetic iron slag from contact with the bottom of the furnace, thereby reducing the frozen layer. (24) Slag feeding and re-reduction Once the slag in the top-blown furnace has been reduced, upstream and downstream processes can be contacted and copper matte can be added to enter the slag-forming period. The copper matte feed rate and smelting coefficient, the reducing coal feed rate and reducing coal coefficient can be adjusted to reduce the magnetic iron oxide content in the slag and reduce the frozen layer. When the copper matte feed rate reaches 10t, the feed rate can be increased, the smelting excess coefficient can be increased, the axial flow fan can be kept off, the cooling water flow rate of the furnace bottom steel shell can be increased, and normal operation can begin.

2. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In steps (1) and (2), the sampling rod is 15.7m long and 70mm in diameter. Its length is the same as the height of the furnace. It is lowered into the top-blown furnace. The length of the sampling rod that protrudes from the top of the furnace is the thickness of the frozen layer at the bottom of the furnace.

3. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (11), the back pressure of the spray gun is above 50 kPa; the fixed carbon content of the reducing coal is >60%, the lump coal particle size is 10-15 mm, and the copper matte grade Cu content is 59%-63%; the adjustment of the reducing coal feed rate and reducing coal coefficient is specifically as follows: control the reducing feed rate to 1.5 t / h coal, control the reducing coal combustion coefficient to 7000 Nm = t, and control the reducing coal excess coefficient to 120%; the strong oxidation time is 6 min.

4. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (12), the flow rate of the cooling water for the furnace bottom steel shell is increased to 130% of the normal flow rate; the axial flow fan has a diameter of 615mm, a power of 2200W, and an air volume of 18700m³. 3 / h of station-type axial flow fan; the reduced flow rate of cooling water for the furnace bottom steel shell is the normal flow rate.

5. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (21), the flow rate of the cooling water in the furnace bottom steel shell is reduced to 70% of the normal flow rate; the back pressure of the spray gun is above 45 kPa; the adjustment of the reducing coal feed rate and reducing coal coefficient specifically involves controlling the reducing coal feed rate to 2.5 t / h and controlling the reducing coal combustion coefficient to 6600 Nm. 3 / t, the excess coefficient of reducing coal is 85%; the heating time is 6min; the spray gun is raised above the surface of the molten pool for 3min; the temperature is raised to 1280-1300℃.

6. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (22), adjusting the reducing coal feed rate and reducing coal coefficient specifically involves controlling the reducing coal feed rate to 2.5 t / h and controlling the reducing coal combustion coefficient to 6600 Nm. 3 / t, with a reduced coal surplus coefficient of 85%.

7. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (23), the back pressure of the spray gun is above 35 kPa; the adjustment of the reducing coal feed rate and reducing coal coefficient specifically involves controlling the reducing coal feed rate to 4.5 t / h and controlling the reducing coal combustion coefficient to 3000 Nm. 3 / t, the excess coefficient of reducing coal is 85%; the reduction time is 6min, and the reduction endpoint is determined by referring to the CO content in the flue gas of the blowing furnace, when the CO content in the flue gas reaches 1000-1200ppm.

8. The method for controlling the thickness of the frozen layer at the bottom of a top-blown furnace according to claim 1, characterized in that, In step (24), adjusting the copper matte feed rate and smelting coefficient specifically involves controlling the copper matte feed rate to 30-35 t / h and the smelting coefficient to 800 Nm. 3 / t, smelting excess coefficient 85%; the adjustment of reducing coal feed rate and reducing coal coefficient specifically refers to: controlling the reducing coal feed rate to 3t / h, and the reducing coal combustion coefficient to 6600Nm. 3 / t, the excess coefficient of reducing coal is 70%; the increased flow rate of cooling water for the furnace bottom steel shell is the normal flow rate.

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