Method for comprehensively utilizing silicon mud and phosphorite to make balls and smelt yellow phosphor

Abstract

This invention discloses a method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, belonging to the technical fields of yellow phosphorus production and photovoltaic solid waste recycling. This invention utilizes elemental silicon from the silica mud in the photovoltaic industry as a reducing agent, partially replacing the coking coal used in traditional yellow phosphorus production; simultaneously, the silica generated from the reaction completely replaces the silica added separately in traditional yellow phosphorus production. During the smelting process, elemental silicon in the silica mud participates in the reaction as a reducing agent at high temperatures, replacing part of the reducing agent (such as coking coal). At the same time, the silica generated from the reaction can replace the added silica in the traditional process. This invention uses elemental silicon or active silicon components from the silica mud to partially replace the traditional reducing agent (coking coal), constructing a new phosphate rock reduction reaction pathway, thus improving the yellow phosphorus production process while realizing the resource utilization of solid waste.

Description

Technical Field

[0001] This invention belongs to the technical field of yellow phosphorus production and photovoltaic solid waste recycling, and particularly relates to a method for smelting yellow phosphorus by comprehensively utilizing silica mud and phosphate rock to form pellets. Background Technology

[0002] Yellow phosphorus is an important basic chemical raw material, widely used in pesticides, phosphoric acid, flame retardants, and food additives. Currently, the industrial production of yellow phosphorus mainly employs the electric furnace method, which uses lumpy phosphate rock, purchased silica, and coke as raw materials, completing the carbothermic reduction reaction in a high-temperature electric furnace at 1400–1500℃. While this process is mature for industrial application, it faces several industry bottlenecks: First, the electric furnace has stringent requirements for the particle size and lumpyness of the raw materials; a large amount of phosphate rock powder generated during mining, beneficiation, and ore processing cannot be directly fed into the furnace, resulting in low utilization of low-grade phosphate rock resources. Second, the carbothermic reduction process is entirely endothermic, leading to high electricity consumption per ton of phosphorus and poor energy efficiency. Third, the reaction generates large amounts of carbon monoxide tail gas and solid slag; CO is flammable and explosive, resulting in high carbon emission intensity, and the disposal of solid waste and tail gas places a heavy environmental burden on the environment.

[0003] To address the problem of idle and wasted phosphate rock powder, the industry has long been engaged in the research and development of phosphate rock powder pelletizing technology. Several patents have disclosed mature phosphate rock powder pelletizing processes, such as CN101973536A. This patent uses phosphate concentrate powder combined with coke powder and high-purity purchased silica powder, supplemented with sodium humate binder to form pellets. Although it achieves the pelletizing and feeding of phosphate rock powder into the furnace and slightly improves the utilization rate of phosphorus resources, this carbothermic pelletizing system has inherent shortcomings: the reducing component is completely dependent on coke, which cannot reduce CO emissions at the source; the silicon source is entirely dependent on purchased silica minerals, without supporting industrial solid waste resource utilization pathways; the pellets have no exothermic reducing component, so the energy saving improvement is limited, and the binder is only suitable for conventional coarse-grained mineral powders, not for ultrafine, highly active siliceous waste. Furthermore, the existing technology CN115594158A discloses a process for preparing yellow phosphorus by silicothermic reduction of silicon slag, which uses metallurgical silicon slag to replace part of the coke to achieve CO-free production. However, this scheme can only consume metallurgical silicon slag alone and cannot simultaneously process phosphate rock powder. Moreover, the silicon slag has low elemental silicon content, many impurities, and insufficient reduction activity. At the same time, the entire process requires a closed furnace and an inert protective atmosphere, which is incompatible with existing yellow phosphorus electric furnaces, resulting in high modification costs and difficulty in large-scale implementation. In summary, both of the existing mainstream technologies have obvious limitations. There is still a lot of room for optimization and improvement in the raw material composition design of phosphate rock powder pellets: there is a lack of a composite batching system that can simultaneously consume two types of industrial solid waste, a carbon-silicon synergistic reduction mechanism has not been constructed, it is impossible to simultaneously achieve the dual replacement of reducing agent and slag-forming silica, and there is also a lack of matching molding and smelting solutions suitable for ultrafine, highly active siliceous solid waste.

[0004] In recent years, the photovoltaic industry has expanded rapidly, and the industrial silicon smelting and silicon ingot / rod cutting processes continuously generate large amounts of ultrafine solid waste, photovoltaic silicon sludge. Photovoltaic silicon sludge is rich in high-purity elemental silicon and possesses extremely strong reducing activity, theoretically making it a suitable raw material for silicothermic reduction. However, this material generally has a particle size of less than 1µm, low bulk density, loose volume, and is highly prone to dust generation, making storage and transportation difficult. Furthermore, its ultrafine particle size, high reactivity, and trace amounts of cutting aid impurities distinguish it from metallurgical silicon slag and industrial silica, making it a research subject specifically for photovoltaic solid waste and not a conventional raw material for the yellow phosphorus smelting industry. Directly feeding it into electric furnaces presents multiple technical challenges, including easy pulverization, furnace condition loss of control, and reduced phosphorus recovery. Currently, there is no mature technology in the industry to co-generate pellets of photovoltaic silicon sludge and phosphate rock powder for use in yellow phosphorus electric furnace production. At present, photovoltaic silicon sludge is mostly disposed of through stockpiling and landfilling, which not only wastes a large amount of high-value elemental silicon resources but also causes environmental problems such as soil and water pollution.

[0005] Therefore, overcoming the technical difficulties of ultra-fine photovoltaic silicon mud being difficult to form and highly active furnace conditions being easily disturbed, and achieving efficient and stable synergistic blending of phosphate rock powder and photovoltaic silicon mud, two types of cross-industry solid wastes, to prepare composite pellet furnace materials with both excellent high-temperature strength and high reducing activity, is the core key to opening up the industrial disposal of photovoltaic silicon mud and the low-carbon transformation of yellow phosphorus production. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock. This invention partially replaces the traditional reducing agent (coking phosphate) with elemental silicon or active silicon components from the silica mud, constructing a new phosphate rock reduction reaction pathway. This improves the yellow phosphorus production process while simultaneously achieving the resource utilization of solid waste.

[0007] To achieve the above objectives, this invention provides a method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: The phosphate rock powder, silica mud, and binder are mixed evenly to obtain a mixture; The mixture is pelletized, and the resulting green pellets are dried to obtain dried pellets; The yellow phosphorus electric furnace charge, reducing agent, and the dried pellets are mixed and smelted to obtain yellow phosphorus.

[0008] The method of this invention is used for the co-processing of solid waste from the photovoltaic industry and phosphate rock powder waste generated from yellow phosphorus production, which can reduce carbon monoxide emissions and overall energy consumption during the yellow phosphorus production process. Under high-temperature conditions, the elemental silicon contained in the silica sludge acts as a reducing agent, which can partially replace the coking coal used in traditional yellow phosphorus production; the elemental silicon participates in the reduction reaction to generate silica, and this self-produced silica can completely replace the silica added in the traditional process. The main reaction equation of the system is: 2Ca3(PO4)2 + 5Si = 6CaO + 5SiO2 + 2P2↑.

[0009] The CaO generated from the decomposition of phosphate rock can spontaneously combine with the SiO2 produced in the reaction to form calcium silicate, thus completing the slag formation process. No external purchase or supplement of silica raw materials is required throughout the smelting process.

[0010] Furthermore, the mass ratio of the phosphate rock powder to the silica mud is (5-9):1. The amount of silica mud added must ensure that its elemental silicon content and the molar ratio of it to the phosphate rock meet the stoichiometric requirements of the silyothermal reduction reaction.

[0011] Furthermore, the silica sludge is waste generated by the photovoltaic industry.

[0012] Furthermore, the amount of the binder added is 3 to 5% of the total mass of the phosphate rock powder and silica mud.

[0013] Furthermore, the binder is phosphoric acid.

[0014] Furthermore, the drying temperature is 200–500 °C. Drying serves to achieve high-temperature consolidation, and the drying process can be carried out in a chain grate rotary kiln, belt roaster, or vertical shaft furnace to ensure the pellets have sufficient strength.

[0015] Furthermore, the mass ratio of the dried pellets to the yellow phosphorus electric furnace charge is 1:(3-5).

[0016] Furthermore, the amount of reducing agent added is 4-8% of the total mass of the phosphate rock powder and silica mud.

[0017] In this invention, the amounts of phosphate rock powder, silica mud, binder, and reducing agent added meet the quality requirements of yellow phosphate rock.

[0018] Furthermore, the reducing agent is pyroxene.

[0019] Furthermore, the smelting temperature is 1400–1500 °C, and the time is 1–2 h.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a novel resource utilization approach that combines photovoltaic industry solid waste with yellow phosphorus production, offering several beneficial effects: First, it achieves dual substitution in terms of reducing agent and raw materials. For the first time, it systematically utilizes the high content of elemental silicon in photovoltaic silicon sludge as both the main reducing agent and silicon source, partially replacing the traditional yellow phosphorus production process that relies entirely on coke and silica, thus improving reduction reaction efficiency. Second, it achieves significant emission reduction and cleaner production. Based on the silicothermic reduction reaction (2Ca3(PO4)2 + 5Si → 6CaO + 2P2↑ + 5SiO2), it reduces the generation of large amounts of carbon monoxide gas in traditional reduction processes at the source, thereby lowering carbon emissions. Simultaneously, it achieves synergistic resource utilization of solid waste across industries, transforming both photovoltaic cutting silicon sludge and phosphate rock powder from yellow phosphorus production into high-value yellow phosphorus products, simultaneously solving the environmental problems caused by silicon sludge storage and the resource utilization challenges of phosphate rock powder. Furthermore, it has the potential to promote the green transformation of the industry. Silicothermic reduction is an exothermic reaction, which helps reduce reaction temperature and system power consumption, demonstrating energy-saving potential. This process is compatible with existing yellow phosphorus electric furnaces, requires minimal retrofitting investment, and provides a practical and feasible technical path for the green and low-carbon transformation of the yellow phosphorus industry. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] Embodiments of the present invention provide a method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: The phosphate rock powder, silica mud, and binder are mixed evenly to obtain a mixture; The mixture is pelletized, and the resulting green pellets are dried to obtain dried pellets. Yellow phosphorus is obtained by mixing the charge material (i.e., the standard ore for smelting yellow phosphorus), the reducing agent, and the dried pellets in a yellow phosphorus electric furnace and then smelting it.

[0027] In a preferred embodiment of the present invention, the mass ratio of phosphate rock powder to silica mud is (5-9):1.

[0028] For example, phosphate rock powder is phosphate rock powder produced during the mining process of phosphate rock or phosphate rock powder produced during the processing and transportation of phosphate rock, with a P2O5 content of 28-35%.

[0029] In a preferred embodiment of the present invention, the particle size of the phosphate rock powder is 100 mesh.

[0030] In a preferred embodiment of the present invention, the silica mud is waste generated during the silicon wafer cutting process in the photovoltaic industry, and the content of elemental silicon can reach 70-97%.

[0031] In a preferred embodiment of the present invention, the amount of binder added is 3 to 5% of the total mass of phosphate rock powder and silica mud.

[0032] In a preferred embodiment of the present invention, the binder is phosphoric acid.

[0033] The phosphoric acid used in this invention is dilute phosphoric acid with a concentration of 30%.

[0034] In an embodiment of the present invention, the particle size of the green pellets is 10–20 cm.

[0035] For example, pelletizing is carried out in a disc pelletizer or a double-roll pelletizer.

[0036] In a preferred embodiment of the invention, the drying temperature is 200–500 °C. The purpose of drying is to give it good mechanical strength.

[0037] In a preferred embodiment of the present invention, the mass ratio of dried pellets to yellow phosphorus electric furnace charge is 1:(3-5).

[0038] In a preferred embodiment of the present invention, the amount of reducing agent added is 4 to 8% of the total mass of phosphate rock powder and silica mud.

[0039] In a preferred embodiment of the present invention, the reducing agent is pyroxene.

[0040] In a preferred embodiment of the present invention, the smelting temperature is 1400–1500 °C and the time is 1–2 h.

[0041] This invention provides a method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock. The method involves mixing silica mud generated from the photovoltaic industry with phosphate rock powder and a binder produced during the production process of phosphate mines and yellow phosphorus enterprises to obtain a mixture. The mixture is then formed into pellets with a particle size of 10–20 cm, which are dried by baking at 200–500 °C to prepare pellets with good strength. These pellets are then mixed with standard ore for yellow phosphorus smelting and smelted in an electric furnace to produce qualified industrial yellow phosphorus. This method combines the photovoltaic industry and the yellow phosphorus smelting industry. Since photovoltaic silica mud contains a large amount of metallic silicon, which can act as a strong reducing agent, it can partially replace the pyroxene reducing agent used in traditional yellow phosphorus production. Simultaneously, the silica generated during the reaction can replace the silica added separately in traditional yellow phosphorus production, providing a new approach to solid waste treatment in the photovoltaic industry and reducing the pressure of high energy consumption and high carbon emissions in yellow phosphorus production. This invention effectively solves the environmental problems caused by silica sludge storage and reduces the production of large amounts of carbon monoxide (CO) gas in the traditional reduction process of yellow phosphorus production, providing a new path for the green and sustainable development of the yellow phosphorus industry. The chemical equation for the traditional process of producing yellow phosphorus is: 2Ca3(PO4)2 + 6SiO2 + 10C = 6CaSiO3 + 10CO↑ + P4↑. The chemical equation after replacing the reducing agent coking coal and the flux silica with silica sludge is: 2Ca3(PO4)2 + 5Si = 6CaO + 5SiO2 + 2P2↑. As can be seen from the equation, this invention comprehensively utilizes silica sludge, reduces the amount of coking coal used in the yellow phosphorus production process, reduces CO emissions, and reduces the amount of flux silica used.

[0042] In the following embodiments of the present invention, the conventional yellow phosphorus electric furnace charge (standard block raw material without the silica mud composite pellets of the present invention) is composed of the following by mass percentage: 70% to 78% block phosphate rock, 12% to 18% industrial silica, and 10% to 14% coke.

[0043] Raw material quality control standards: P2O5 ≥ 28% for lumpy phosphate rock, SiO2 ≥ 96% for silica, and fixed carbon ≥ 80% for coke; the particle size of each raw material is controlled within 10-50mm, meeting the requirements for materials fed into the existing yellow phosphorus electric furnace.

[0044] The conventional electric furnace charge is a common carbon-thermal basic charge in the industry and is a common batching scheme for existing industrial yellow phosphorus production lines. This invention mixes self-made phosphate rock-silica mud dried pellets into this standard charge at a mass ratio of 1:(3~5) and smelts them together in the furnace. With the help of silica mud, it can simultaneously replace some of the coke in the system and completely replace the added silica, thereby reducing the consumption of coke and the amount of purchased silica used.

[0045] Unless otherwise specified, the room temperature in this invention is 25 ± 2℃.

[0046] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0047] The technical solution of the present invention will be further illustrated by the following embodiments.

[0048] Comparative Example 1: Traditional full-carbothermic reduction process Currently, the main industrial production of yellow phosphorus uses the electric furnace process. This method typically involves mixing phosphate rock, silica, and coke in a specific ratio and placing the mixture into an electric furnace for a carbothermic reduction reaction at 1300–1500°C. The reaction produces high-temperature phosphorus-containing furnace gas, which is then purified through dust removal, condensation, washing, and separation to obtain industrial yellow phosphorus. Molten slag is periodically discharged from the bottom of the electric furnace. This traditional process has significant energy efficiency, environmental, and safety drawbacks: producing 2800–3100 m³ of process waste gas per ton of yellow phosphorus produced. 3 The exhaust gas contains 80%–90% CO by volume. Carbon monoxide is a flammable and explosive gas; if air seeps into the furnace, it can easily form an explosive mixture, posing a significant production safety risk. Furthermore, traditional all-carbon thermal processes have high overall energy consumption, with each ton of yellow phosphorus requiring 14,800–15,000 kWh of electricity. In addition to CO, the furnace gas also contains toxic pollutants such as fluorides and phosphides, requiring large-scale exhaust gas purification and incineration treatment equipment. This results in high equipment investment and long-term operation and maintenance costs, a complex overall process, and high carbon emission intensity.

[0049] Example 1 A method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: (1) Raw material preparation: Take phosphate rock powder (P2O5 content of about 25% (mass percentage, the same below) and 100 mesh) produced during the production of yellow phosphorus, silicon mud (elemental silicon dry basis content of about 85% (mass percentage, the same below)) produced during the photovoltaic silicon wafer cutting process, and prepare dilute phosphoric acid (concentration of 30% (mass percentage, the same below)) as a binder. (2) Ingredients and mixing: Based on a total mass of 100 parts by weight of phosphate rock powder and silica mud, the ratio of phosphate rock powder to silica mud is 9:1, that is, 90 parts by weight of phosphate rock powder and 10 parts by weight of silica mud; the amount of dilute phosphoric acid added is 4% of the total mass of phosphate rock powder and silica mud. All materials are thoroughly mixed to obtain a mixture.

[0050] (3) Pelletizing: The uniform mixture is pressed into raw pellets with a diameter of 10 cm in a double roller pelletizing machine; (4) Drying of green balls: The green balls are baked and dried at 250°C to give them good mechanical strength; (5) Electric furnace smelting: The dried pellets obtained in step (4) are mixed with traditional yellow phosphorus electric furnace charge at a mass ratio of 1:5. 7% (7 parts by weight) of secondary coke was added as a supporting agent. After all materials were mixed evenly, they were fed into the experimental electric furnace. The furnace was smelted at 1500℃ for 1.2 hours, with elemental silicon in the silica mud participating in the reaction as the main reducing agent.

[0051] Results: The reaction was stable, with a final phosphorus recovery rate of 89%, a carbon monoxide (CO) volume fraction of 17.5% in the furnace gas, and a comprehensive power consumption of 12,350 kWh per ton of yellow phosphorus. Compared with the traditional full-carbon thermal reduction process in Comparative Example 1, this embodiment significantly reduced the CO content in the furnace gas and also significantly reduced the power consumption for phosphorus production.

[0052] Example 2 A method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: (1) Raw material preparation: Take phosphate rock powder (P2O5 content of about 28%) stored by yellow phosphorus enterprise and another batch of photovoltaic cutting silicon mud (elemental silicon dry basis content of about 90%); and prepare dilute phosphoric acid (concentration of 30%) as binder. (2) Batching and mixing: Based on a total mass of 100 parts by weight of phosphate rock powder and silica mud, the materials are batched according to a mass ratio of 5:1, i.e., 83.3 parts by weight of phosphate rock powder and 16.7 parts by weight of silica mud; the amount of dilute phosphoric acid added is 5% of the total mass of phosphate rock powder and silica mud (upper limit of the range), and the mixture is stirred until the materials are uniform to obtain the mixture.

[0053] (3) Pelletizing: The uniform mixture is pressed into raw pellets with a diameter of 10 cm in a double roller pelletizing machine; (4) Drying of green balls: The green balls are baked and dried at 250°C to give them good mechanical strength; (5) Electric furnace smelting: The dried pellets are mixed with conventional yellow phosphorus electric furnace charge at a mass ratio of 1:4; 4% secondary coke (lower limit of range) is added based on the total mass of phosphate rock powder and silica mud; the mixture is smelted at a constant temperature of 1400-1500 ℃ for 1.5 h, and the highly active elemental silicon in the silica mud participates in the silicothermic reduction reaction as the main reducing agent.

[0054] Results: The smelting furnace conditions were stable, with no abnormalities such as agglomeration, material collapse, or phosphorus enrichment in the mud. The produced yellow phosphorus product met the national standard for industrial grade one yellow phosphorus (GB / T 7816-2018). In this embodiment, the overall phosphorus recovery rate reached 92.3%, the CO volume fraction in the furnace gas decreased to 12.2%, and the overall power consumption per ton of yellow phosphorus was 11,950 kWh. Compared with the traditional full carbothermal reduction process in Comparative Example 1, power consumption was reduced by approximately 10.5%, CO emissions were significantly reduced, and the co-treatment of solid waste was remarkably effective.

[0055] Example 3 A method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: (1) Raw material preparation: Phosphate rock powder from the yellow phosphorus production process is selected, with a P2O5 mass fraction of 25% and a particle size of 100 mesh; silicon mud from photovoltaic silicon wafer cutting is selected, with a dry basis elemental silicon mass fraction of 90%; the binder is 30% dilute phosphoric acid; the auxiliary reducing agent is secondary metallurgical coke.

[0056] (2) Ingredients and mixing: Based on the total mass of 100 parts by weight of phosphate rock powder and silica mud, the phosphate rock powder: silica mud mass ratio is 6:1, that is, 85.7 parts by weight of phosphate rock powder and 14.3 parts by weight of silica mud; the amount of dilute phosphoric acid added is 4% of the total mass of phosphate rock powder and silica mud. The mixture is thoroughly stirred to obtain the mixture.

[0057] (3) Pelletizing: The uniform mixture is fed into a double roller briquetting machine and pressed into large green pellets with a diameter of 20 cm. (4) Drying of green pellets: The green pellets are baked and dried at a high temperature of 500 ℃ to achieve deep consolidation, greatly improve the high temperature heat strength of the pellets, and meet the requirements of large pellets for furnace smelting.

[0058] (5) Electric furnace smelting: The dried pellets are mixed with conventional yellow phosphorus electric furnace charge at a mass ratio of 1:3 and fed into the furnace; based on the total mass of phosphate rock powder and silica mud, 5.5% of secondary coke is added; the furnace is reduced and smelted at a constant temperature of 1500 ℃ for 1.5 h, with the silica mud elemental silicon participating in the reaction as the main reducing component.

[0059] Results: The smelting process was stable and continuous, with good furnace permeability and stable furnace conditions. The final overall phosphorus recovery rate reached 90.7%, the CO volume fraction in the furnace gas was 14.6%, and the overall power consumption per ton of yellow phosphorus was 12,120 kWh. This embodiment is suitable for the production of large-size, high-strength pellets, combining high phosphorus recovery rate with excellent energy-saving and carbon-reduction effects.

[0060] Example 4 A method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, comprising the following steps: (1) Raw material preparation: Phosphate rock powder from the yellow phosphorus production process with a P2O5 mass fraction of 25% and a particle size of 100 mesh is selected; silicon mud produced by industrial silicon smelting is selected with a dry basis elemental silicon mass fraction of 70%; the binder is 30% dilute phosphoric acid; the auxiliary reducing agent is secondary metallurgical coke.

[0061] (2) Ingredients and mixing: Based on the total mass of 100 parts by weight of phosphate rock powder and silica mud, the mixture is prepared according to the mass ratio of phosphate rock powder to silica mud of 7:1, that is, 87.5 parts by weight of phosphate rock powder and 12.5 parts by weight of silica mud; the amount of dilute phosphoric acid added is 3.5% of the total mass of phosphate rock powder and silica mud. The mixture is thoroughly stirred to obtain a mixture.

[0062] (3) Ball making: The uniform mixture is pressed into raw balls with a diameter of 20 cm in a double roller ball press.

[0063] (4) Drying of green pellets: The green pellets are placed at a constant temperature of 300 ℃ for drying to ensure that the pellets have excellent cold and hot mechanical strength.

[0064] (5) Electric furnace smelting: The dried pellets and conventional yellow phosphorus electric furnace charge are mixed evenly at a mass ratio of 1:4 and fed into the furnace; based on the total mass of phosphate rock powder and silica mud, 6% of secondary coke is added; the furnace is smelted at a constant temperature of 1500 ℃ for 1.5 h, and the elemental silicon in the silica mud participates in the silicothermic reduction reaction as the main reducing agent.

[0065] Results: The overall smelting operation was stable and highly adaptable, suitable for industrial silicon sludge solid waste with low to medium elemental silicon content. The final phosphorus recovery rate reached 89.8%, the CO volume fraction in the furnace gas was 16.3%, and the comprehensive power consumption per ton of yellow phosphorus was 12260 kWh. Compared with the traditional all-carbothermic process, both energy consumption and carbon emissions were significantly reduced, demonstrating strong process versatility.

[0066] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock, characterized in that, Includes the following steps: The phosphate rock powder, silica mud, and binder are mixed evenly to obtain a mixture; The mixture is pelletized, and the resulting green pellets are dried to obtain dried pellets. Yellow phosphorus is obtained by mixing the yellow phosphorus electric furnace charge, reducing agent and the dried pellets, and then smelting it.

2. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The mass ratio of the phosphate rock powder to the silica mud is (5-9):

1.

3. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 2, characterized in that, The silica mud is waste generated by the photovoltaic industry.

4. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The amount of binder added is 3 to 5% of the total mass of the phosphate rock powder and silica mud.

5. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 4, characterized in that, The adhesive is phosphoric acid.

6. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The drying temperature is 200–500 °C.

7. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The mass ratio of the dried pellets to the yellow phosphorus electric furnace charge is 1:(3-5).

8. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The amount of reducing agent added is 4-8% of the total mass of the phosphate rock powder and silica mud.

9. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 8, characterized in that, The reducing agent is pyroxene.

10. The method for smelting yellow phosphorus by pelletizing silica mud and phosphate rock according to claim 1, characterized in that, The smelting temperature is 1400–1500 ℃, and the isothermal smelting time is 1–2 h.