Automatic sinking method for semi-closed high carbon ferrochrome submerged arc furnace

Abstract

The present invention discloses an automatic material sinking method for a semi-enclosed high-carbon ferrochrome ore furnace, comprising the following steps: S1: checking the dimensions of the material pipe, including adjusting the length and angle of the material nozzle; S2: implementing the automatic material sinking process, including stabilizing the furnace condition and implementing automatic material sinking of material pipes in different areas; S3: matching the operating system, stabilizing the structure of the furnace charge layer, and ensuring balanced material sinking to achieve stable and smooth furnace conditions; S4: exiting and re-activating the automatic material sinking process before and after the ore furnace is shut down for maintenance, achieving continuous automatic material sinking. The present invention has the following beneficial effects: achieving material layer stability, reducing heat loss and employee labor intensity, lowering costs, promoting performance indicators, resolving various drawbacks of the intermittent material sinking process, and achieving long-term stable operation of the furnace condition and equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of ferroalloy production, and in particular relates to an automatic material sinking method for a semi-closed high-carbon ferrochrome ore furnace. Background Art

[0002] High-carbon ferrochrome is an alloy of chromium and iron, also containing other elements such as carbon and silicon. Ferrochrome with a carbon content of 4% to 10% is considered high-carbon chromium and is a widely used and highly produced ferrochrome alloy.

[0003] There are two ways of unloading high carbon ferrochrome ore furnaces. One is intermittent unloading, which is mainly used in semi-closed ore furnaces; the other is continuous automatic sinking, which is currently used in closed ore furnaces.

[0004] In recent years, the trend toward larger and more enclosed submerged arc furnaces has become a development trend in the ferroalloy smelting industry, and a nationally mandated requirement for new submerged arc furnace construction. A fundamental process in large, enclosed submerged arc furnaces is automatic charge sinking, as these furnaces cannot perform intermittent charge distribution or material level maintenance.

[0005] Up to now, domestic semi-enclosed high-carbon ferrochrome submerged arc furnaces basically adopt intermittent unloading and use a tamping machine (forklift) to maintain the material surface. First, the process is relatively backward, the unloading is very random, and it is impossible to realize automatic unloading on demand. The material surface temperature is high, the heat loss is large (the furnace mouth temperature is more than 50°C higher than the automatic sinking temperature), and the heat utilization rate is reduced, which to a certain extent restricts the progress of economic and technical indicators; second, the use of a tamping machine to maintain the material surface, on the one hand, the working time of personnel in a high temperature environment is long and the labor intensity is high; on the other hand, manual operation of the tamping machine to maintain the material surface will cause damage to the material layer structure, affecting the overall process of submerged arc furnace smelting, resulting in a mismatch between the material melting rate and the reduction rate, and a low alloy recovery rate; third, the material pipe works at high temperature, and there is no material at the lower end for insulation or heat resistance (the lower end of the automatic sinking material pipe is all material), resulting in a high burnout rate of the material pipe, a short service life of the material pipe, and high cost.

[0006] The semi-closed submerged arc furnace can effectively solve this problem by implementing the automatic sinking process. Summary of the Invention

[0007] The purpose of the present invention is to provide an automatic material sinking method for a semi-closed high-carbon ferrochrome ore furnace, which can achieve the stability of the material layer, reduce heat loss and labor intensity of employees, reduce costs, promote the improvement of indicators, solve the various disadvantages of the intermittent material unloading process, and realize the automatic material sinking process of a semi-closed high-carbon ferrochrome ore furnace with long-term stable operation of the furnace condition and equipment.

[0008] The technical solution adopted in the present invention is:

[0009] The semi-closed submerged arc furnace implements the automatic sinking method, which includes the following steps:

[0010] S1: Check the size of the material tube, including the adjustment of the nozzle 8 length and nozzle angle A;

[0011] S2: Implementation of automatic sinking process, including stabilizing furnace conditions and automatic sinking of material pipes in different areas;

[0012] S3: Match the operating system, stabilize the charge layer structure, sink evenly, and achieve stable and smooth furnace conditions;

[0013] S4: Automatic sinking process is exited and put into use before and after the submerged arc furnace is shut down for maintenance, realizing continuous automatic sinking;

[0014] In the preferred step S1, in the step S1, the length of the nozzle 8 is adjusted: according to the material surface height and material surface shape requirements, combined with the natural stacking angle of the material under automatic sinking, the length of the nozzle 8 can be extended into the furnace by 200-500mm; the material cannot bury the equipment in the furnace to ensure that the natural material surface meets the process requirements after automatic sinking; the adjustment of the nozzle angle A: the nine material tubes of the outer ring of the furnace body ring 9, that is, the nozzle angle A of the large material tube 1 and the small material tube 2 is adjusted from horizontal to inclined 30℃-45℃ toward the furnace core; the nozzles of the three alternate material tubes 3 and the one furnace core material tube 7 are maintained in a horizontal state to ensure that the automatically sunk material is evenly distributed according to the process requirements, in a shape with a high center and a low periphery, and the furnace core material The height of tube 7 and large material tube 1 is 200mm-400mm higher than that of small material tube 2; ensure that the automatically sunk materials are evenly distributed according to the process requirements, and are in a shape with a high center and a low periphery. The height of the furnace core material tube 7 and large material tube 1 is 200mm-400mm higher than that of the small material tube 2, to avoid the increase in material column pressure after automatic sinking and cause furnace ore fluctuations; the material tubes at different positions implement automatic sinking in stages mainly to ensure the stability of the furnace condition during the automatic sinking process, and to avoid repeated furnace conditions after one-time unloading; ensure that the shape of the furnace charge after automatic sinking is in a shape with a high center and a low outer circle, which meets the characteristics and requirements of fast material circulation in the center and slow material circulation in the outer circle during the smelting process of the electric arc furnace.

[0015] The automatic sinking described in the preferred step S2 is implemented, and the material pipes in different areas are automatically sunk: the material is automatically sunk in the order of the core material pipe 7 first, then the interphase material pipe 3, and finally the furnace body ring 9, that is, the large material pipe 1 and the small material pipe 2. The hydraulic gate at the top of the material pipe and the bottom of the silo is opened and kept open. The material is automatically sunk continuously under its own weight as it is consumed in the furnace by smelting. First, the core material pipe 7 in the center is automatically sunk. After 3-5 days, the three material pipes of the interphase material pipe 3 are opened to start self-sinking; finally, the nine material pipes in the ring, that is, the large material pipe 1 and the small material pipe 2 are opened for self-sinking. The operation is divided into three stages, with 3-5 days as one operation stage. The changes in the furnace condition after automatic sinking in each stage are observed to ensure that after the previous stage is advanced, the furnace condition is stable and smooth and the production indicators are normal before entering the next stage to avoid blind advancement and recurrence.

[0016] The preferred operating system matching described in step S3 is that the weak carbon amplitude of the furnace core material tube 7 is between 2%-4%, the weak carbon amount is 4.2-9.6kg, the current is reduced by 2% to 195A, and the material circulation rate in the outer ring dead material area is accelerated; the secondary voltage is 200V-225V, and the molten pool in the furnace is active, which can alleviate the problem of increased dead weight of the material layer caused by the automatic sinking of the material, make the material sink evenly, and achieve stable and smooth furnace condition, solving the problem of abnormal furnace condition caused by the change of material surface height after the automatic sinking of the semi-fully enclosed electric arc furnace and the increase of the pressure of the material column in the furnace.

[0017] In the preferred step S4, the automatic sinking process is exited and put into use before and after the submerged arc furnace is shut down for maintenance, so as to realize continuous automatic sinking;

[0018] Automatic material discharge before maintenance: The material level is controlled by unloading on demand, creating conditions for maintenance of equipment and material pipes in the furnace; the hydraulic gate is opened to realize automatic material discharge, which is carried out in the reverse order of operation, first large material pipe 1, then small material pipe 2, then interphase material pipe 3, and finally core material pipe 7;

[0019] The use of automatic material sinking after maintenance: During the furnace condition recovery stage after maintenance, the first three furnaces of iron are discharged intermittently and the material level of the furnace top hopper is controlled. The material level of the furnace top hopper is controlled for 3-6 furnaces to facilitate adjustments during the furnace condition recovery period. After 6 furnaces of iron are discharged and the furnace condition returns to normal, automatic material sinking is put into use and executed in the order of step S2.

[0020] The beneficial effects of the present invention are:

[0021] 1) In the present invention, intermittent unloading refers to the transportation of chromium-containing materials, coke and auxiliary materials to the furnace top silo through the burdening system according to the process ratio. A hydraulic gate is set at the connection area (21 meters) between the furnace top silo and the upper part of the material pipe, and a second gate is set at the connection area between the nozzle 8 and the lower part of the material pipe. In daily production, according to the melting and descending conditions of the materials in the furnace, the two hydraulic gates are manually controlled by the operating handle to realize intermittent unloading. After the materials enter the furnace, they are pushed by the furnace tamping machine to ensure that the materials reach the designated area for smelting; automatic sinking is based on the distribution characteristics of the furnace and the requirements of the smelting process. After the nozzle angle A and the length of the nozzle 8 are matched, the hydraulic valve that controls the sinking of the materials is opened, and the materials are automatically and continuously sunk. The unloading process has good stability and continuity of the unloading layer, does not require manual assistance in unloading and pushing, and the labor intensity of employees is greatly reduced. At the same time, the materials are fully preheated, heat loss is reduced, and the heat utilization rate is high.

[0022] 2) In the original intermittent feeding process, the material pipe is about 600mm above the horizontal plane of the furnace mouth. The normal production material level is controlled between 200-400mm above the furnace mouth. In order to ensure that the material level is consistent with it after automatic sinking, the length of the nozzle 8 needs to be extended 200-400mm into the furnace to ensure that the natural material level meets the process requirements after automatic sinking.

[0023] 3) After the implementation of this process, the semi-closed submerged arc furnace can automatically sink the material, greatly reducing the heat loss in the furnace. The furnace mouth temperature drops by 50-100℃ year-on-year, effectively reducing the probability of burning of equipment in the furnace and preventing all kinds of equipment accidents.

[0024] 4) After the implementation of this process, the semi-closed submerged arc furnace can automatically sink the material, the temperature of the material layer in the furnace is fully preheated, the heat utilization rate is greatly improved, the smelting power consumption is reduced by about 150-200℃ year-on-year, and the recovery rate is increased by more than 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the layout structure of the furnace ring material pipe in the present invention;

[0026] Figure 2 This is a schematic structural diagram of the furnace core tube of the present invention;

[0027] Figure 3 This is a schematic structural diagram of a large fabric tube according to the present invention;

[0028] Figure 4 This is a schematic structural diagram of a small fabric tube according to the present invention;

[0029] Figure 5 This is a schematic structural diagram of the interphase material pipe of the present invention;

[0030] In the figure: 1. Large material tube, 2. Small material tube, 3. Interphase material tube, 4. B phase electrode, 5. A phase electrode, 6. C phase electrode, 7. Core material tube, 8. Material nozzle. DETAILED DESCRIPTION

[0031] The following will be combined with the attached Figure 1-5 The present invention is further described.

[0032] Example 1

[0033] The semi-closed submerged arc furnace implements the automatic sinking method, which includes the following steps:

[0034] S1: Check the size of the material pipe, including the adjustment of the length of the material nozzle 8 and the material nozzle angle A; Adjustment of the length of the material nozzle 8: According to the requirements of the material surface height and material surface shape, combined with the natural stacking angle of the material under automatic sinking, the length of the material nozzle 8 can be extended by 300mm into the furnace; Adjustment of the material nozzle angle A: The nine material pipes on the outer ring of the furnace body ring 9, that is, the material nozzle angle A of the large material pipe 1 and the small material pipe 2, are adjusted from horizontal to 30° inclined toward the furnace core; The material nozzles of the three alternate material pipes 3 and the one furnace core material pipe 7 are maintained in a horizontal state to ensure that the automatically sunk materials are evenly distributed according to the process requirements, in a shape with a high center and a low periphery. The height of the furnace core material pipe 7 and the large material pipe 1 is 200mm-400mm higher than the height of the small material pipe 2.

[0035] S2: Implementation of automatic sinking process, including stabilizing furnace conditions and automatic sinking of material pipes in different areas; automatic sinking of material pipes in different areas: first the core material pipe 7, then the interphase material pipe 3, and finally the furnace ring 9, i.e. the large material pipe 1 and the small material pipe 2, in this order, automatically sink the material, open the hydraulic gates on the top of the material pipe and the bottom of the silo and keep them open, and the material automatically sinks continuously under its own weight as it is consumed in the furnace by smelting, first the core material pipe 7 in the center automatically sinks, and after 3-5 days the three interphase material pipes 3 are opened to start self-sinking; finally the nine material pipes in the ring, i.e. the large material pipe 1 and the small material pipe 2 are opened for self-sinking, and the operation is divided into three stages, with 3-5 days as one stage, and the changes in the furnace condition after automatic sinking in each stage are observed to ensure that after the previous stage, the furnace condition is stable and smooth and the production indicators are normal before entering the next stage, to avoid blind advancement and recurrence.

[0036] S3: Matching the operating system, stabilizing the structure of the charge layer, evenly sinking the charge, and achieving stable and smooth furnace conditions; matching the operating system: that is, the weak carbon amplitude of the furnace core charge tube 7 is between 2%-4%, the weak carbon amount is 4.2-9.6kg, the current is reduced by 2% to 195A, and the material circulation rate in the outer dead material area is accelerated; the secondary voltage is 200V-225V, which activates the molten pool in the furnace, can alleviate the problem of increased dead weight of the charge layer caused by automatic sinking of the material, make the material sink evenly, and achieve stable and smooth furnace conditions, solving the problems of abnormal furnace conditions caused by changes in material surface height and increased pressure of the charge column in the furnace after the semi-fully enclosed ore furnace automatically sinks.

[0037] S4: The automatic material sinking process is exited and put into use before and after the electric arc furnace is shut down for maintenance to realize continuous automatic material sinking; the exit of automatic material sinking before maintenance: the material surface is controlled by unloading on demand to create conditions for the maintenance of equipment and material pipes in the furnace; the hydraulic gate is opened to realize the exit of automatic material sinking, which is executed in the reverse order of operation, first the large material pipe 1, the small material pipe 2, then the interlaced material pipe 3, and finally the core material pipe 7; the use of automatic material sinking after maintenance: in the stage of furnace condition recovery after maintenance, the first 3 furnaces of iron are organized by intermittent unloading and controlling the material level of the furnace top hopper, and the material level of the furnace top hopper is controlled for 3-6 furnaces to facilitate adjustment during the recovery of the furnace condition. After 6 furnaces of iron are discharged and the furnace condition returns to normal, the automatic material sinking is put into use again, and it is executed in the order of step S2.

[0038] In this embodiment, by adjusting the nozzle angle A and the length of the nozzle 8, the material can automatically sink to the designated area after automatic sinking, and there is no need to manually operate the tamping machine to maintain the material surface, which greatly reduces the labor intensity of employees; at the same time, the residual heat from the furnace mouth under automatic sinking continues to preheat the material, and the furnace mouth temperature drops by 80°C year-on-year. Within one year, the equipment in the furnace is intact, there is no equipment failure, the smelting power consumption decreases by 160kwh / t year-on-year, the recovery rate increases by 2.1%, and the cost per ton of iron decreases by about 150 yuan.

[0039] Example 2

[0040] The semi-closed submerged arc furnace implements the automatic sinking method, which includes the following steps:

[0041] S1: Check the size of the material pipe, including the adjustment of the length of the material nozzle 8 and the material nozzle angle A; Adjustment of the length of the material nozzle 8: According to the requirements of the material surface height and material surface shape, combined with the natural stacking angle of the material under automatic sinking, the length of the material nozzle 8 can be extended by 400mm into the furnace; Adjustment of the material nozzle angle A: The nine material pipes on the outer ring of the furnace body ring 9, that is, the material nozzle angle A of the large material pipe 1 and the small material pipe 2, are adjusted from horizontal to 35° inclined toward the furnace core; The material nozzles of the three alternate material pipes 3 and the one furnace core material pipe 7 are maintained in a horizontal state to ensure that the automatically sunk material is evenly distributed according to the process requirements, in a shape with a high center and a low periphery. The height of the furnace core material pipe 7 and the large material pipe 1 is 200mm-400mm higher than the height of the small material pipe 2.

[0042] S2: Implementation of automatic sinking process, including stabilizing furnace conditions and automatic sinking of material pipes in different areas; automatic sinking of material pipes in different areas: first the core material pipe 7, then the interphase material pipe 3, and finally the furnace ring 9, i.e. the large material pipe 1 and the small material pipe 2, in this order, automatically sink the material, open the hydraulic gates on the top of the material pipe and the bottom of the silo and keep them open, and the material automatically sinks continuously under its own weight as it is consumed in the furnace by smelting, first the core material pipe 7 in the center automatically sinks, and after 3-5 days the three interphase material pipes 3 are opened to start self-sinking; finally the nine material pipes in the ring, i.e. the large material pipe 1 and the small material pipe 2 are opened for self-sinking, and the operation is divided into three stages, with 3-5 days as one stage, and the changes in the furnace condition after automatic sinking in each stage are observed to ensure that after the previous stage, the furnace condition is stable and smooth and the production indicators are normal before entering the next stage, to avoid blind advancement and recurrence.

[0043] S3: Matching of operating system, stabilizing the structure of charge layer, evenly sinking, and realizing stable and smooth furnace condition; matching of operating system: that is, the weak carbon amplitude of furnace core charge tube 7 is between 4%, the weak carbon amount is 9.6kg, the current is reduced by 2% to 195A, and the material circulation rate in the outer dead material area is accelerated; the secondary voltage is 225V, which activates the molten pool in the furnace, and can alleviate the problem of increased dead weight of the charge layer caused by automatic sinking of the material, so that the material sinks evenly and realizes stable and smooth furnace condition, and solves the problem of abnormal furnace condition caused by the change of material surface height after automatic sinking of the semi-fully enclosed ore furnace and the increase of pressure of the charge column in the furnace.

[0044] S4: The automatic material sinking process is exited and put into use before and after the electric arc furnace is shut down for maintenance to realize continuous automatic material sinking; the exit of automatic material sinking before maintenance: the material surface is controlled by unloading on demand to create conditions for the maintenance of equipment and material pipes in the furnace; the hydraulic gate is opened to realize the exit of automatic material sinking, which is executed in the reverse order of operation, first the large material pipe 1, the small material pipe 2, then the interlaced material pipe 3, and finally the core material pipe 7; the use of automatic material sinking after maintenance: in the stage of furnace condition recovery after maintenance, the first 3 furnaces of iron are organized by intermittent unloading and controlling the material level of the furnace top hopper, and the material level of the furnace top hopper is controlled for 3-6 furnaces to facilitate adjustment during the recovery of the furnace condition. After 6 furnaces of iron are discharged and the furnace condition returns to normal, the automatic material sinking is put into use again, and it is executed in the order of step S2.

[0045] In this embodiment, by adjusting the nozzle angle A and the length of the nozzle 8, the material can automatically sink to the designated area after automatic sinking, and there is no need to manually operate the tamping machine to maintain the material surface, which greatly reduces the labor intensity of employees; at the same time, the residual heat from the furnace mouth under automatic sinking continues to preheat the material, and the furnace mouth temperature drops by 60°C year-on-year. Within one year, the equipment in the furnace is intact, there is no equipment failure, the smelting power consumption drops by 150kwh / t year-on-year, the recovery rate increases by 1.8%, and the cost per ton of iron drops by about 120 yuan.

Claims

1. Automatic material sinking method for semi-closed high carbon ferrochrome submerged arc furnace, characterized in that: The steps include: S1: Check the size of the material pipe, including the adjustment of the nozzle (8) length and the nozzle angle A. The nozzle (8) length adjustment can be extended by 200-500mm into the furnace according to the material surface height and material surface shape requirements, combined with the natural stacking angle of the material under the automatic sinking; Adjustment of the nozzle angle A: The nozzle angles A of the nine material tubes on the outer ring of the furnace body ring (9), namely the large material tube (1) and the small material tube (2), are adjusted from horizontal to inclined 30°C-45°C toward the furnace core; the nozzles of the three alternate material tubes (3) and the one furnace core material tube (7) are kept horizontal to ensure that the automatically sinking materials are evenly distributed according to the process requirements, in a shape with a high center and a low periphery. The height of the furnace core material tube (7) and the large material tube (1) is 200mm-400mm higher than the height of the small material tube (2); S2: Implementation of automatic sinking process, including stabilizing furnace conditions and automatic sinking of material pipes in different areas; S3: Match the operation system, stabilize the charge layer structure, and ensure balanced material sinking to achieve stable and smooth furnace operation; The operating system is matched, that is, the weak carbon amplitude of the furnace core material tube (7) is between 2% and 4%, the weak carbon amount is 4.2-9.6 kg, the current is reduced by 2% to 195A, and the material circulation rate in the outer ring dead material area is accelerated; the secondary voltage is 200V-225V to activate the molten pool in the furnace; S4: The automatic sinking process is exited and put into use before and after the submerged arc furnace is shut down for maintenance, realizing continuous automatic sinking.

2. The automatic sinking method for a semi-enclosed high-carbon ferrochrome submerged arc furnace according to claim 1, characterized in that: In step S2, the furnace condition is stabilized: before the automatic sinking is implemented, it must be ensured that the furnace condition is normal and forward; Automatic sinking of material pipes in different areas: First, the core material pipe (7), then the interphase material pipe (3), and finally the furnace ring (9), i.e., the large material pipe (1), the small material pipe (2) are automatically sunk in this order. The hydraulic gates at the top of the material pipe and the bottom of the silo are opened and kept open. The material automatically sinks continuously under its own weight as it is consumed in the furnace. First, the core material pipe (7) in the center is automatically sunk. After 3-5 days, the three interphase material pipes (3) are opened to start self-sinking. Finally, the nine material pipes in the ring, i.e., the large material pipe (1) and the small material pipe (2), are opened to start self-sinking. The operation is divided into three stages, with 3-5 days as one stage. The changes in the furnace condition after automatic sinking in each stage are observed.

3. The automatic material sinking method for a semi-enclosed high-carbon ferrochrome submerged arc furnace according to claim 1, characterized in that: The withdrawal and commissioning of the automatic sinking of the submerged arc furnace before and after the planned maintenance in step S4; Automatic material withdrawal before maintenance: adopt the method of material discharge on demand to control the material level, creating conditions for the maintenance of equipment and material pipes in the furnace; open the hydraulic gate to realize automatic material withdrawal, and execute it in the reverse order of use, first the large material pipe (1), then the small material pipe (2), then the interleaved material pipe (3), and finally the core material pipe (7); The use of automatic material sinking after maintenance: During the furnace condition recovery stage after maintenance, the first three furnaces of iron are discharged intermittently and the material level of the furnace top hopper is controlled. The material level of the furnace top hopper is controlled for 3-6 furnaces to facilitate adjustments during the furnace condition recovery period. After 6 furnaces of iron are discharged and the furnace condition returns to normal, automatic material sinking is put into use and executed in the order of step S2.

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