Combined holder furnace profile ferrosilicon alloy production method

Abstract

The invention provides a combined holder furnace type ferrosilicon alloy production method, which relates to the technical field of metallurgical engineering, and comprises the following steps: determining the dosage of silica, semi-coke and iron products, feeding the ingredients into a submerged arc furnace for smelting, feeding smelted molten iron into a ladle, transferring the molten iron to an ingot mold for pouring, demolding after pouring and cooling, analyzing and warehousing, and crushing and finishing. When abnormal production conditions occur, fluorite pellets are added to the root of the electrode to relieve the crusting condition of the charge level and digest the poor working end shape of the electrode. According to the invention, the problems of easy fin burning loss and low equipment operation rate of the combined holder furnace profile in ferrosilicon alloy production are effectively solved, and the energy-saving advantage of the combined holder furnace profile is fully exerted.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical engineering, in particular to a method for producing ferrosilicon alloy in a combined holder furnace. Background Art

[0002] At present, the industry mainly relies on the production of semi-closed submerged arc furnaces for ferrosilicon alloys. Submerged arc furnaces can be divided into copper tile furnaces and combined controller furnaces according to the differences in the structure of the control system.

[0003] The combined gripper furnace offers significant advantages over traditional copper-tile furnaces. Its conductive elements are clamped to the outer ribs of the electrode shell via disc springs, resulting in a superior conductive contact surface. This results in significantly better contact resistance and electrical efficiency than copper-tile furnaces. Years of production experience and data tracking and analysis have shown that combined gripper furnaces can achieve a 5% improvement in energy savings compared to copper-tile furnaces. Furthermore, the combined gripper furnace is simpler in construction, making overhaul and maintenance significantly less difficult and less expensive than copper-tile furnaces.

[0004] However, based on years of industry experience, existing modular gripper furnaces are relatively mature in slag-based smelting processes such as calcium carbide and silicon-manganese alloys, but their application in ferrosilicon production has been more challenging. This is primarily due to the slag-free smelting process, which eliminates the need for additional slagging agents during batching. However, during production, the charge surface is prone to sintering, forming a crust, leading to electrode freezing and, ultimately, frequent contactor rib burnout. Compared to copper tile furnaces, modular gripper furnaces have relatively low equipment utilization rates in ferrosilicon production.

[0005] Furthermore, due to inherent structural defects in the lower gripper of the combined gripper furnace, operators needed to frequently lift the electrodes to prevent rib burnout. This long-term operation caused the furnace floor to rise, creating a vicious cycle and ultimately forcing the furnace to be unloaded. These issues severely restricted the full utilization of the energy-saving advantages of the combined gripper furnace, necessitating an urgent need to optimize and adjust the ferrosilicon alloy production process for this type of furnace.

[0006] Chinese patent CN104342595A discloses a production process for ferrosilicon alloy. This solution prepares ferrosilicon alloy by mixing silica, semi-coke / coke, and iron pellets in a specific proportion and then feeding the mixture into a submerged arc furnace for smelting at a temperature of 1570°C-1850°C for 2.5-4 hours. However, this method focuses on solving the problem of raw material substitution and does not provide solutions to the unique problems of combined gripper furnaces in ferrosilicon production, such as crusting on the material surface, electrode blocking leading to rib burning, and low equipment operation rate.

[0007] Therefore, how to effectively solve the technical problems faced by the combined gripper furnace in the production of ferrosilicon alloys, such as surface crusting, electrode blocking and rib burning, improve the equipment operation rate and give full play to its energy-saving advantages, is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for producing ferrosilicon alloy using a combined holder furnace to solve the technical problems of surface crusting, electrode blocking and rib burning faced by the combined holder furnace in the production of ferrosilicon alloy, thereby improving the equipment operation rate.

[0009] To achieve the above object, the present invention is implemented through the following technical solution: a method for producing ferrosilicon alloy in a combined holder furnace, characterized in that it includes the following steps:

[0010] S1: Determine the raw material proportions of silica, semi-coke, and iron products according to the planned production grade of ferrosilicon alloy. These raw materials are mixed in proportion to form the top material, which is then fed into the submerged arc furnace for smelting.

[0011] S2: After smelting, the molten iron enters the ladle and is transferred to the ingot mold for fixed-point casting. After casting and cooling, it is demoulded, the ferrosilicon is analyzed and stored, and crushed, refined and batched.

[0012] S3: When production abnormalities occur, add fluorite pellets to the root of the electrode to eliminate the production abnormalities.

[0013] Furthermore: the production abnormalities include: difficulty in the electrode working during the operation of the material surface, resulting in obstruction of material discharge from the material surface layer, sintering to form a hard shell layer on the furnace material surface, the length of the single-phase electrode exceeds the electrode diameter by more than 1.8 times, the shape of the working end of the material surface electrode has a pointed tip and the electrode petals fall off with a stepped cross-section.

[0014] Furthermore: the amount of fluorite pellets added is controlled to not exceed 600 kg every 8 hours.

[0015] Furthermore: the physical and chemical requirements of the fluorite pellets are: particle size of 1-10mm, mass ratio of CaF2 ≥ 70%, SiO2% ≤ 20%, S < 0.1%, P < 0.05%, TiO2 ≤ 0.05%, particle size below 1mm ≤ 3%.

[0016] Furthermore, the proportion of silica, semi-coke and iron products is as follows: each time the charge is 600 kg in total, of which silica is fixed at 300 kg; semi-coke is added at 230±15 kg; and iron products are added at 60±5 kg.

[0017] Furthermore: when the current in the furnace is lower than 280A, the reaction rate is slow to every 30 minutes, and there is no obvious change in the material surface, the amount of lignite added should be appropriately increased by up to 15kg; when the aluminum element in the product in the furnace is higher than 2.0%, the amount of lignite added should be appropriately reduced by up to 15kg.

[0018] Furthermore: the submerged arc furnace is a 16500KVA furnace type, and the process parameter requirements are: the distance between the electrode and the material surface ≤ 60cm, the primary current ≤ 345A, the primary voltage 35.5±3KV, the active power ≥ 14500KW, and the power factor COSб ≥ 0.8.

[0019] Further: the following steps are also included:

[0020] S4: The silicon slag produced during the fixed-point pouring process is recycled and converted back into silica, which is then mixed with semi-coke and iron products.

[0021] S5: The high-temperature gas generated during the smelting process of the submerged arc furnace is recovered through waste heat to generate electricity and fed into the power grid and short-circuit grid;

[0022] S6: The flue gas passes through cyclone dust removal, bag filter dust removal and metering bag before being sold.

[0023] Furthermore, when the temperature of the fluorite pellets reaches above 1450 degrees, they react with the silicate slag mainly composed of silicon dioxide and metal oxides generated during ferrosilicon smelting to generate calcium fluorosilicate.

[0024] Furthermore, when the temperature of the fluorite pellets reaches above 750 degrees, fluorine element is decomposed.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention effectively solves the problems of surface crusting and electrode working end shape in the production of ferrosilicon alloys using a combined gripper furnace. The calcium fluoride in the fluorite pellets reacts with the high-melting-point components in the furnace, lowering the melting point of the slag and improving the fluidity of the slag. This effectively alleviates the phenomenon of surface crusting, while also eliminating the poor working end shape of the electrode and avoiding the risk of electrode freezing. It also significantly improves the equipment operating rate of the combined gripper furnace in the production of ferrosilicon alloys. By reducing the frequency of rib burnout accidents and avoiding downtime and maintenance due to rib burnout, the equipment maintenance costs and downtime losses are significantly reduced, making the production process more stable and continuous.

[0027] Second, this invention solves the problem of furnace bottom swelling caused by frequent electrode lifting in ferrosilicon alloy production using a combination gripper furnace. The addition of fluorite pellets improves the charge surface, reducing the need for electrode lifting. This avoids the vicious cycle of furnace bottom swelling and production issues caused by prolonged electrode lifting, significantly extending the equipment's continuous operation cycle.

[0028] 3. This invention fully utilizes the high electrical efficiency advantage of the combined gripper furnace. By optimizing the furnace operating conditions, the combined gripper furnace can achieve a 5% improvement in energy savings compared to the copper tile furnace, balancing production stability and energy efficiency.

[0029] 4. The present invention improves the permeability of the charge, loosens the charge surface, promotes the discharge of gas in the furnace, optimizes the reaction conditions in the furnace, avoids the problem of unstable furnace conditions caused by gas retention, improves the production quality and production efficiency of ferrosilicon alloy as a whole, and reduces the comprehensive energy consumption per unit product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic flow chart of a combined holder furnace-type ferrosilicon alloy production method provided by the present invention;

[0031] Figure 2 A schematic diagram of the process flow of a combined holder furnace-type ferrosilicon alloy production method provided by the present invention;

[0032] Figure 3 The present invention provides a schematic process flow diagram of a combined holder furnace-type ferrosilicon alloy production method using new ingredients. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] like Figure 1-2 The figure shows the combined gripper furnace-type ferrosilicon alloy production process proposed in this invention. First, the raw material quantities of silica, semi-coke, and iron products are determined based on the planned ferrosilicon alloy grade. These raw materials are then proportioned to form the top charge. The control room controls the batching and feeding process, feeding the top charge into the submerged arc furnace for smelting. Under normal production conditions, the proportions of silica, semi-coke, and iron products are as follows: each charge totals 600 kg, with a fixed silica content of 300 kg, semi-coke of 230 ± 15 kg, and iron products of 60 ± 5 kg.

[0035] Silica is the primary source of silicon in ferrosilicon production. During the chemical reaction, a certain amount of silica is required to ensure sufficient reaction with the carbonaceous reducing agent and the iron product to produce the desired ferrosilicon grade. Semi-coke, as a carbonaceous reducing agent, provides the carbon needed to reduce the silicon in the silica during the smelting process. Based on years of practical experience, 230 kg of semi-coke can fully react with 300 kg of silica, reducing the silicon in the silica and combining it with the iron in the iron product to form ferrosilicon. This amount ensures sufficient reducing power while maintaining a relatively stable chemical reaction within the furnace, avoiding problems such as incomplete reaction or excessive temperature fluctuations within the furnace caused by excessive or insufficient reducing agent.

[0036] Since the furnace condition is affected by many factors, such as the difference in particle size of raw materials, uneven temperature distribution in the furnace, and the influence of operating techniques, the amount of lignite needs to be appropriately adjusted. The range of ±15kg provides room for fine-tuning during the production process. When the current of the furnace electrode is lower than 280A, the reaction rate is as slow as every 30 minutes, and there is no obvious change in the material surface, appropriately increasing the amount of lignite (up to 15kg) can enhance the reduction reaction, increase the furnace temperature, and promote the reduction of silica; when the aluminum content in the furnace product is higher than 2.0%, appropriately reducing the amount of lignite (up to 15kg) can avoid runaway reaction and ensure the smooth reaction in the furnace, thereby ensuring the stability of product quality. Iron products are dynamically adjusted according to the required product requirements and are generally controlled at around 60kg.

[0037] After smelting, the molten iron enters a ladle and is transferred to ingot molds for targeted casting. This process produces slag. After the casting cools, the ingots are demolded, and the ferrosilicon is analyzed and stored. It is then crushed, sized, and batched for sale. The silicon slag produced during the targeted casting process is recycled and converted back into silica, which is then mixed with semi-coke and iron products. The high-temperature gases generated during the smelting process in the submerged arc furnace are recovered through waste heat recovery for power generation, which is then fed into the power grid and short-circuit grid. The flue gas passes through a cyclone dust collector, a bag filter, and metering bags before being sold.

[0038] The core of this invention lies in adding fluorite pellets to the electrode base when production anomalies occur to alleviate surface crusting and improve the poor working end shape of the electrode. These anomalies include: difficulty in electrode work during surface manipulation, resulting in obstructed surface material discharge; formation of a crusty layer on the charge surface during sintering; single-phase electrode length exceeding 1.8 times the electrode diameter; and the appearance of a pointed tip at the working end of the electrode, as well as electrode petal loss and a stepped cross-section. The amount of fluorite pellets added should be controlled to no more than 600 kg per eight hours.

[0039] Fluorite pellets are spherical products made by pelletizing equipment after fluorite ore has been processed through a series of processing steps such as beneficiation, crushing and grinding, with the addition of suitable binding agents. The main component of the pellets is CaF2. The physical and chemical requirements of the fluorite pellets used in the present invention are as follows: a particle size of 1-10 mm, a mass ratio of CaF2 ≥ 70%, SiO2 % ≤ 20%, S < 0.1%, P < 0.05%, TiO2 ≤ 0.05%, and a particle size of 1 mm or less or less than 3%. When the temperature of the fluorite pellets reaches 1450 degrees or more, they react with silicate slag generated in ferrosilicon smelting with silicon dioxide (SiO2) and metal oxides such as CaO, MgO, Al2O3, etc., which are the main components, to generate calcium fluorosilicate, which changes the composition and properties of the slag in ferrosilicon alloy production, reduces the melting point of the slag, and improves the fluidity of the slag. Simultaneously, the partial fluorine element decomposed under the high temperature of the fluorite pellets has an erosive effect on the electrode, and is used to consume the poorer part of the electrode working end.

[0040] By adding fluorite pellets to the base of the electrode, they sink into the charge and function under high-temperature conditions, improving charge permeability, loosening the charge surface, promoting gas discharge, and optimizing reaction conditions within the furnace. The calcium fluoride in the fluorite pellets reacts chemically with high-melting-point components in the charge to form low-melting-point fluorides, lowering their melting point and enabling them to melt at lower temperatures. This helps mitigate the formation of a crust on the charge surface and the formation of a thin tip at the working end of the electrode, which can cause the electrode to sit and die, thus preventing rib burnout.

[0041] The present invention is suitable for the production of ferrosilicon alloy in a combined holder furnace of a 16500KVA furnace type, and the process parameter requirements are: the distance between the electrode and the material surface is ≤60cm, the primary current is ≤345A, the primary voltage is 35.5±3KV, the active power is ≥14500KW, and the power factor COSб is ≥0.8.

[0042] It should be noted that the electrode bottom ring is part of the electrode system and is the lowest device in the electrode system. The distance between the electrode and the material surface is specifically the distance between the electrode bottom ring and the material surface.

[0043] The working principle of the present invention is as follows:

[0044] The working principle of the combined holder furnace type ferrosilicon alloy production process of the present invention is to add fluorite pellets to the root of the electrode under specific production conditions, and utilize the physical and chemical properties of the fluorite pellets to improve the working conditions in the furnace, thereby solving the unique problems faced by the combined holder furnace type in ferrosilicon production.

[0045] In the ferrosilicon alloy production process, the combined gripper furnace offers advantages such as high electrical efficiency, simple equipment structure, and low maintenance costs. However, its design, in which the conductive elements are clamped to the outer ribs of the electrode shell by disc springs, is prone to rib burnout due to sintering of the material surface into a shell and electrode seating in the slag-free ferrosilicon alloy smelting process. The traditional solution is to frequently lift the electrodes, but this practice, when continued, causes the furnace bottom to rise, leading to a vicious cycle of production and ultimately requiring furnace removal, which seriously affects production efficiency and equipment utilization.

[0046] The core of this invention is to introduce fluorite pellets as a regulator, solving the above-mentioned problems through its special reaction mechanism under high temperature conditions. When a combined gripper furnace for ferrosilicon alloy production encounters abnormalities such as a lack of feed opening, no feed, crusting on the feed surface during operation, or when a single-phase electrode is too long, exceeding 1.8 times the electrode diameter, or when the electrode working end is poorly shaped, resulting in a pointed tip, or when the electrode petals fall off, resulting in a stepped cross-section, etc., fluorite pellets are added to the electrode root. The working principle is as follows:

[0047] First, after entering the furnace, the fluorite pellets sink into the charge and react with the silicic acid slag at high temperatures. Calcium fluoride (CaF2), the main component of the fluorite pellets, reacts with high-melting-point components in the charge, such as silicon dioxide (SiO2), to form low-melting-point compounds such as calcium fluorosilicate. This chemical reaction alters the composition and properties of the slag originally used in ferrosilicon production, significantly lowering its melting point and improving its fluidity. This lower melting point and improved fluidity effectively alleviate the problem of crusting on the charge surface, keeping it loose and facilitating the proper discharge of gases from the furnace, thereby improving the heat transfer environment within the furnace.

[0048] Secondly, when the temperature of fluorite pellets reaches above 750°C, they decompose into fluorine, which corrodes the carbonaceous electrode. While this corrosive effect increases electrode wear, it can, in certain circumstances, be used to eliminate poorly defined areas on the electrode's working end. When the electrode's working end develops a pointed tip or a stepped cross-section, the corrosive effect of fluorine preferentially consumes these irregularities, restoring the electrode's working end to a more ideal shape and preventing electrode freezing caused by poor working end shape.

[0049] Third, the addition of fluorite pellets improves the permeability of the charge. During the ferrosilicon alloy smelting process, the permeability of the charge directly affects the gas discharge and heat distribution within the furnace. Poor permeability can lead to localized gas accumulation, resulting in uneven pressure and temperature distribution within the furnace, which in turn affects the smelting results and the working condition of the electrodes. The addition of fluorite pellets reduces the viscosity of the slag and increases its fluidity, making the overall structure of the charge more porous. This significantly improves the charge's permeability, promotes the uniform discharge of gas within the furnace, and maintains a more stable pressure and temperature distribution within the furnace.

[0050] Through the aforementioned mechanism, the present invention significantly reduces the risk of rib burnout in ferrosilicon production using a combined gripper furnace, reduces the need for electrode lifting, and avoids the problem of furnace bottom swelling caused by frequent electrode lifting, fundamentally breaking the vicious cycle of production conditions. This allows the combined gripper furnace to fully utilize its high electrical efficiency advantage in ferrosilicon production, achieving the goal of energy conservation and consumption reduction.

[0051] It is worth noting that the amount of fluorite pellets added needs to be strictly controlled within an appropriate range (no more than 600kg every 8 hours). Experiments have shown that when the amount added is too high (such as 800kg), it will lead to excessive dilution of the slag, seriously weakening the slag's protective effect on the furnace lining, affecting the heat transfer efficiency in the furnace, leading to unstable furnace temperature and increased energy consumption. When the amount added is too low (such as 200kg), the effect of improving the permeability of the charge and the reaction in the furnace is not obvious enough, and it cannot effectively solve the production abnormality problem.

[0052] Furthermore, the physical and chemical properties of fluorspar pellets also directly impact their performance. The present invention requires fluorspar pellets with a particle size of 1-10mm, CaF2 ≥ 70%, SiO2 ≤ 20%, S < 0.1%, P < 0.05%, TiO2 ≤ 0.05%, and a particle size below 1mm ≤ 3%. These specifications ensure that the fluorspar pellets perform optimally in the furnace without introducing excessive impurities that could affect product quality.

[0053] The present invention cleverly solves the unique technical difficulties of the combined gripper furnace type in the production of ferrosilicon alloy by utilizing the chemical reaction characteristics and physical action mechanism of fluorite pellets under high temperature conditions, enabling the combined gripper furnace type to fully exert its inherent advantages in the field of ferrosilicon alloy production, thereby achieving a dual improvement in technological progress and economic benefits.

[0054] The present invention will be further described below through specific examples and comparative examples.

[0055] Example 1:

[0056] In the production of ferrosilicon alloy in a 16,500 kVA combined gripper furnace, the normal batching ratio was used: 300 kg of silica, 230 kg of semi-coke, and 60 kg of iron products per batch. However, during production, surface crusting was observed during material handling. The single-phase electrodes were excessively long, exceeding 1.8 times their diameter, and the working ends of the electrodes had a pointed shape. Therefore, the batching was adjusted, and 500 kg of fluorite pellets were added to the electrode base. The physical and chemical properties of the fluorite pellets were as follows: particle size 5 mm, CaF2 = 75%, SiO2 = 15%, S = 0.08%, P = 0.03%, TiO2 = 0.04%, and particle size below 1 mm = 2%.

[0057] Two hours after adding the fluorite pellets, the material surface at the electrode root was significantly loosened, crusting was alleviated, the shape of the electrode working end gradually improved, and the electrode length returned to normal. Energy consumption was well controlled during production, with electricity consumption per ton of product being approximately 7,650 kWh / t. The furnace operated smoothly, eliminating the need for frequent adjustments to operating parameters and significantly improving production efficiency.

[0058] Example 2:

[0059] During the production of ferrosilicon alloy in a 16500 kVA combined gripper furnace, the same proportions as in Example 1 were used. During the production process, it was discovered that the material surface was not being fed, and significant petal shedding occurred at the electrode working end, resulting in a stepped cross-section. At this point, 600 kg of fluorite pellets were added to the electrode root. The physical and chemical properties of the fluorite pellets were as follows: particle size 3-8 mm, CaF2 = 72%, SiO2 = 18%, S = 0.09%, P = 0.04%, TiO2 = 0.03%, and particle size below 1 mm = 2.5%.

[0060] After adding fluorite pellets, the permeability of the material surface improved significantly, the chipping phenomenon at the working end of the electrode gradually disappeared, and the stepped cross-section gradually became smoother. Production indicators stabilized, with power consumption per ton of product reduced to 7700kWh / t, no rib burnout occurred, and the equipment utilization rate increased by 15%.

[0061] Comparative Example 1:

[0062] Under the same conditions as in Example 1, when the amount of fluorite pellets added was 800 kg, it was observed that the slag was over-diluted, which weakened the protective effect of the slag on the furnace lining, affected the heat transfer efficiency in the furnace, caused the furnace temperature to be unstable, increased the energy consumption to 8200 kWh / t, and caused local overheating.

[0063] Comparative Example 2:

[0064] Under the same conditions as in Example 1, when the amount of fluorite pellets added is only 200 kg, the improvement effect on the permeability of the charge and the reaction in the furnace is not obvious, the crusting phenomenon on the charge surface still exists, the shape of the electrode working end is not significantly improved, and the ribs are still at risk of burning.

[0065] It can be seen from the above embodiments and comparative examples that the present invention effectively solves the problems of material surface crusting and electrode working end shape faced by the combination holder furnace in the production of ferrosilicon alloy by adding an appropriate amount of fluorite pellets to the root of the electrode when a specific production abnormality occurs in the production process of ferrosilicon alloy in the combination holder furnace, reduces the risk of rib burning, improves the equipment operation rate, gives full play to the energy-saving advantages of the combination holder furnace, and achieves a dual improvement in technical and economic benefits.

[0066] It should be noted that if Figure 3As shown, the batching structure can also be selected from fluorite pellets, steel chips and limestone, which are mixed and added to the root of the electrode to better deal with production abnormalities.

[0067] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for producing ferrosilicon alloy using a combined holder furnace, characterized in that: The steps include: S1: Determine the raw material proportions of silica, semi-coke, and iron products according to the planned production grade of ferrosilicon alloy. These raw materials are mixed in proportion to form the top material, which is then fed into the submerged arc furnace for smelting. S2: After smelting, the molten iron enters the ladle and is transferred to the ingot mold for fixed-point casting. After casting and cooling, it is demoulded, the ferrosilicon is analyzed and stored, and crushed, refined and batched. S3: When production abnormalities occur, add fluorite pellets to the root of the electrode to eliminate the production abnormalities.

2. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The production abnormalities include: difficulty in the electrode working during the operation of the material surface, resulting in obstruction of material discharge from the material surface layer, formation of a hard shell layer due to sintering of the furnace material surface, the length of the single-phase electrode exceeding the electrode diameter by more than 1.8 times, the shape of the working end of the material surface electrode becoming pointed, and the electrode falling off with a stepped cross-section.

3. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The amount of fluorite pellets added is controlled to be no more than 600 kg per 8 hours.

4. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The physical and chemical requirements of the fluorite pellets are: particle size of 1-10 mm, mass ratio of CaF2 ≥ 70%, SiO2 % ≤ 20%, S < 0.1%, P < 0.05%, TiO2 ≤ 0.05%, and particle size below 1 mm ≤ 3%.

5. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The proportion of silica, semi-coke and iron products is as follows: each time the charge into the furnace is 600 kg in total, of which silica is fixed at 300 kg; semi-coke is added at 230±15 kg; and iron products are added at 60±5 kg.

6. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 4, wherein: When the current in the furnace is lower than 280A, the reaction rate is as slow as every 30 minutes, and there is no obvious change in the material surface, the amount of lignite added should be appropriately increased by up to 15kg; when the aluminum content in the product in the furnace is higher than 2.0%, the amount of lignite added should be appropriately reduced by up to 15kg.

7. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The submerged arc furnace is a 16500KVA furnace type, and the process parameter requirements are: the distance between the electrode and the material surface is ≤60cm, the primary current is ≤345A, the primary voltage is 35.5±3KV, the active power is ≥14500KW, and the power factor COSб is ≥0.

8.

8. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: The following steps are also included: S4: The silicon slag produced during the fixed-point pouring process is recycled and converted back into silica, which is then mixed with semi-coke and iron products. S5: The high-temperature gas generated during the smelting process of the submerged arc furnace is recovered through waste heat to generate electricity and fed into the power grid and short-circuit grid; S6: The flue gas passes through cyclone dust removal, bag filter dust removal and metering bag before being sold.

9. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: When the temperature of the fluorite pellets reaches above 1450 degrees, they react with silicate slag generated in ferrosilicon smelting, which mainly contains silicon dioxide and metal oxides, to generate calcium fluorosilicate.

10. The method for producing ferrosilicon alloy using a combined holder furnace according to claim 1, wherein: When the temperature of the fluorite pellets reaches 750 degrees or above, fluorine element is decomposed.

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