Method for recycling silica fume in ferrosilicon production process

Abstract

The invention relates to the technical field of material purification, in particular to a method for recycling silica fume in the production process of silicon iron. The method for recycling the silica fume comprises the following steps: (1) carrying out winnowing purification on the collected silica fume; (2) carrying out magnetic separation purification on the silica fume obtained in the step (1); (3) drying the micro silicon powder obtained in the step (2) at low temperature; (4) feeding the silica fume obtained in the step (3) into airflow classification equipment for particle size separation; (5) sintering the silica fume obtained in the step (4) at high temperature; (6) carrying out acid pickling, acid leaching and drying on the silica fume obtained in the step (5); (7) cooling the silica fume obtained in the step (6); and (8) crushing and screening the micro-silicon powder obtained in the step (7) to obtain the micro-silicon powder with different particle sizes. The cyclic utilization rate of silicon resources is improved, the cost is low, and the economic value of silicon is improved.

Description

Technical Field

[0001] The invention relates to the technical field of material purification, and in particular to a method for recycling microsilicon powder in a ferrosilicon production process. Background Art

[0002] Ferrosilicon is an iron alloy composed of iron and silicon. Ferrosilicon is an iron-silicon alloy made by smelting in an electric furnace using coke, steel scraps, and quartz (or silica) as raw materials. Since silicon and oxygen can easily combine to form silicon dioxide, ferrosilicon is often used as a deoxidizer in steelmaking. At the same time, since a large amount of heat is released when SiO2 is generated, it is also beneficial to increase the temperature of molten steel while deoxidizing. At the same time, ferrosilicon can also be used as an alloying element additive and is widely used in low-alloy structural steel, spring steel, bearing steel, heat-resistant steel and electrical silicon steel. Ferrosilicon is often used as a reducing agent in ferroalloy production and the chemical industry.

[0003] After rapid growth, my country's ferroalloy production capacity has now entered a high-quality development stage, with total ferroalloy production capacity reaching about 34 million tons / year. With the continuous development and optimization of the industry and the implementation of the dual control of energy consumption and "dual carbon" policies in recent years, the concentration of the industry has increased significantly. At the same time, ferrosilicon, as a "two high" project, has been replaced in many provinces. Therefore, the biggest challenge for existing companies is how to ensure that the existing production capacity can achieve carbon emission reduction and ensure clean and safe production under the increasingly stringent domestic industrial policy regulation and restriction measures on the development of the ferrosilicon industry.

[0004] During the ferrosilicon production process, a large amount of microsilica powder with a particle size less than 150 microns is produced due to crushing, screening, smelting and other processes. This part of microsilica powder is traditionally regarded as waste and is often directly discharged or sold at a low price, which not only wastes resources but also causes serious pollution to the environment. Most existing recycling technologies are inefficient, costly, and difficult to ensure the purity and consistency of the recycled products, limiting the high added value of microsilica powder.

[0005] Ferrosilicon powder, component content: 72%<Si≤80%, Al≤0.05%, Ti≤0.05%, Ca≤0.05%, Mn≤0.05%, Cr≤0.05%, P≤0.04%, S≤0.02%, C≤0.02%, H2O≤0.8%. In the prior art, ferrosilicon powder particles are refined according to customer needs to produce ferrosilicon powder particles of 5-25mm, 10-30mm, and 10-50mm. During the finishing process, about 15% of ferrosilicon powder particles of 0-3mm and 3-8mm will be produced, which can only be sold at a discount. Ferrosilicon powder particles are ancillary products of production, and customers have little willingness to demand them. There are problems such as difficulty in sales, waste of finished products, and low resource utilization.

[0006] For example, Chinese patent application CN113247904A discloses a method for recovering microsilica powder, which includes the following steps: according to a preset material ratio, the microsilica powder, adhesive and reducing agent weighed separately are mixed and mixed to obtain a mixed granulation raw material; the mixed granulation raw material is added to the granulator through the granulation process silo, and the mixed granulation raw material is humidified by spraying water into the granulator, and then granulated to obtain granules; the granules are calcined in a rotary kiln to remove some volatile substances in the granules; the calcined granules are transported to the furnace silo of the high-temperature reduction process through the high-temperature resistant material tank automatic conveying system, and the calcined granules are evenly added to the ore-fired electric furnace through the closed spiral under the furnace silo, and industrial silicon is obtained after high-temperature reduction reaction. The invention can solve the problems of incomplete recovery of microsilica powder in the prior art and low value of recovery. However, it is difficult for the invention to ensure its clean and safe production, and it does not have high economic value.

[0007] For example, Chinese patent CN110182817A discloses a method for recycling silicon micropowder, which includes the following steps: placing the recycled material in a recycling tank, adding clean water, raising the temperature of the recycling tank, standing and settling to obtain a lower layer of sediment; adding a recovery agent to the recycling tank containing the sediment, and then adding deionized water to obtain a first mixed slurry; adding acid to the first mixed slurry, stirring at a uniform speed, standing and settling to obtain a recovery agent layer; placing the recovery agent layer in the recycling tank for heating, and the recovery agent evaporates into a condensation tank under heat, and is condensed and recycled for next use; adding clean water to the recycling tank for washing 2-3 times, filtering, drying, and obtaining recycled silicon micropowder. This invention does not pollute the environment, the recovery agent can be recycled and reused, saving the recycling cost, and effectively improving the recycling efficiency. However, the above-mentioned problems also exist.

[0008] Therefore, there is an urgent need to provide a method for efficiently recycling microsilica powder in the production process of ferrosilicon to improve resource utilization, reduce environmental pollution, achieve green production, and enhance the economic value of microsilica powder. Summary of the invention

[0009] Based on the problems existing in the prior art, the present invention aims to provide a method for efficiently recycling microsilica powder in the process of ferrosilicon production. The present invention realizes high-quality recycling and reuse of microsilica powder through innovative physical and chemical treatment processes, thereby improving the recycling rate of resources.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] The present invention provides a method for recycling microsilicon powder in a ferrosilicon production process, comprising the following steps:

[0012] (1) Purifying the collected microsilica powder by air separation to separate light impurities to obtain microsilica powder 1;

[0013] (2) purifying the microsilica powder 1 obtained in step (1) by magnetic separation to separate ferromagnetic impurities to obtain microsilica powder 2;

[0014] (3) drying the microsilica powder 2 obtained in step (2) at low temperature to obtain microsilica powder 3;

[0015] (4) sending the microsilica powder 3 obtained in step (3) into an air flow classification device for particle size separation to obtain microsilica powder 4;

[0016] (5) sintering the microsilica powder 4 obtained in step (4) at high temperature to obtain microsilica powder 5;

[0017] (6) acid-washing, acid-leaching, and drying the microsilica powder 5 obtained in step (5) to obtain microsilica powder 6;

[0018] (7) cooling the microsilica powder 6 obtained in step (6) to obtain microsilica powder 7;

[0019] (8) The microsilica powder 7 obtained in step (7) is crushed and sieved to obtain microsilica powder of different particle sizes.

[0020] Preferably, the particle size of the microsilica powder in step (1) is 5-10 um.

[0021] Preferably, the air separation purification in step (1) uses wind separation equipment to separate light impurities.

[0022] Preferably, the wind speed of the air purification in step (1) is 10m / s-20m / s, and the air volume is 65-75m 3 / h.

[0023] Preferably, the magnetic separation purification in step (2) utilizes strong magnetic field equipment to separate the microsilicon powder containing ferromagnetic impurities (such as iron filings).

[0024] Preferably, the magnetic separation purification in step (2) adopts high gradient magnetic separation technology, with a magnetic field strength of 1-2T and a magnetic field gradient of 2*10 4 T / m, stainless steel fiber / stainless steel balls can be added to enhance the magnetic field inhomogeneity, the suspension and ionized water are configured in a mass ratio of 1:50, the solid mass fraction of the suspension is between 1%-5%, the flow rate should be 0.1-0.5m / s, the temperature is 20℃-25℃, and the pH value is controlled at 6-8.

[0025] Preferably, the temperature of the low-temperature drying in step (3) is set lower than the critical point temperature of active degradation of microsilica fume.

[0026] Preferably, the temperature of the low-temperature drying in step (3) is 50°C-90°C.

[0027] Preferably, the low-temperature drying in step (3) is equipped with a humidity sensing system to automatically adjust the degree of drying.

[0028] Preferably, the airflow classification equipment in step (4) performs particle size separation by adjusting the airflow velocity, the pressure difference in the classification chamber and the angle of the guide vanes.

[0029] Preferably, the inlet air flow velocity of the air flow classification equipment in step (4) is 10m / s-20m / s, and the outlet air flow velocity is 5m / s-10m / s.

[0030] Preferably, the pressure difference in the classification chamber of the airflow classification equipment described in step (4) is 500Pa-1000Pa.

[0031] Preferably, the angle of the guide vanes of the airflow classification device in step (4) is 10°-15°.

[0032] Preferably, the protective atmosphere selected for the high-temperature sintering in step (5) is argon, nitrogen or one of other inert gases.

[0033] Preferably, the protective atmosphere selected for the high-temperature sintering in step (5) is argon.

[0034] Preferably, the high temperature sintering in step (5) is temperature-controlled sintering.

[0035] Preferably, the high temperature sintering in step (5) uses a temperature-controlled sintering temperature in the range of 800°C to 1000°C.

[0036] Preferably, the high temperature sintering in step (5) uses a temperature-controlled sintering time of 2 h to 4 h, with a heat preservation time of 1 h.

[0037] Preferably, the acid used for pickling in step (6) is at least one of hydrofluoric acid, hydrochloric acid or sulfuric acid.

[0038] Preferably, the sulfuric acid used in the pickling in step (6) is high-temperature sulfuric acid with a concentration of 5% and a temperature of 100°C.

[0039] Preferably, the concentration of hydrofluoric acid in the pickling process of step (6) is 1%, and the concentration of hydrochloric acid is 6 mol / L.

[0040] Preferably, the liquid-to-solid ratio of acid to silicon powder in the pickling process of step (6) is 10-25:1.

[0041] Preferably, the temperature of the acid leaching in step (6) is 75°C-85°C.

[0042] Preferably, the acid leaching time in step (6) is 1-3 hours.

[0043] Preferably, the drying in step (6) is carried out in a drying oven at 90° C. for 24 hours.

[0044] Preferably, the cooling treatment in step (7) is slow cooling.

[0045] Preferably, the cooling time of the cooling treatment in step (7) is 4-6 hours.

[0046] Preferably, the pulverizing in step (8) is performed by pulverizing equipment.

[0047] Preferably, the screening in step (8) adopts a multi-stage screening technology to perform accurate classification according to particle size.

[0048] The present invention also provides a method for testing the performance of the recovered microsilica powder.

[0049] Preferably, the performance testing method includes but is not limited to chemical composition analysis, physical property testing, and microstructure analysis of the modified microsilica fume;

[0050] Preferably, the physical property testing of the modified microsilica powder in the performance testing method includes but is not limited to density, hardness, temperature resistance, FTIR spectrum analysis, contact angle measurement, dispersibility test, compatibility test with specific substrates, etc.;

[0051] The present invention also provides the use of the microsilica powder recycled by the above method in the preparation of high-end materials and other products.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The microsilica powder recovery method provided by the present invention simplifies the recovery process, shortens the intermediate links such as ball making, and reduces energy consumption.

[0054] (2) The present invention significantly improves the purity of silicon powder, effectively recovers micro silicon powder in ferrosilicon production, improves the recycling rate of silicon resources, and reduces resource waste.

[0055] (3) The microsilica powder recovered by the present invention can be applied in the field of high-end materials, thereby improving its economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of a method for recycling microsilicon powder in the ferrosilicon production process DETAILED DESCRIPTION

[0057] The technical scheme of the present invention is clearly and completely described below with specific implementation methods. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited.

[0058] Example 1 A method for recycling microsilicon powder in the process of ferrosilicon production

[0059] The steps include:

[0060] (1) The collected microsilica powder was blown at a wind speed of 10 m / s and a wind volume of 75 m 3 / h under the condition of air separation and purification, light impurities are separated to obtain micro silicon powder 1;

[0061] (2) The microsilica powder 1 obtained in step (1) is separated from ferromagnetic impurities by high gradient magnetic separation technology, with a magnetic field strength of 1.5T and a magnetic field gradient of 2*10 4 T / m, the suspension and ionized water are configured in a mass ratio of 1:50, the flow rate of the suspension is 0.5m / s, the temperature is 25°C, and the pH value is 6, and magnetic separation purification is performed to obtain microsilica powder 2;

[0062] (3) drying the microsilica powder 2 obtained in step (2) at a low temperature of 60° C., and automatically adjusting the degree of drying by a humidity sensing system to obtain microsilica powder 3;

[0063] (4) sending the microsilica powder 3 obtained in step (3) into an airflow classification device for particle size separation under the conditions of an inlet airflow velocity of 10 m / s, an outlet airflow velocity of 5 m / s, a pressure of 500 Pa in the classification chamber, and an angle of 10° for the guide blades to obtain microsilica powder 4;

[0064] (5) The microsilica powder 4 obtained in step (4) is subjected to high-temperature sintering at 800° C. using argon as a protective gas for 2 hours and heat preservation for 1 hour to obtain microsilica powder 5;

[0065] (6) adding 1% hydrofluoric acid and 6 mol / L hydrochloric acid to the microsilica powder 5 obtained in step (5), acid leaching the silicon powder at a liquid-to-solid ratio of 20:1 and an acid leaching temperature of 75°C for 2 hours, and drying the silicon powder in a drying oven at 90°C for 24 hours to obtain microsilica powder 6;

[0066] (7) Slowly cooling the microsilica powder 6 obtained in step (6) for 4 hours to obtain microsilica powder 7;

[0067] (8) The microsilica powder 7 obtained in step (7) is crushed by a crushing device, and then, a multi-stage screening technology is used to accurately classify it according to the particle size to obtain microsilica powder L-1 of different particle sizes.

[0068] Example 2 A method for recycling microsilicon powder in the production process of ferrosilicon

[0069] The steps include:

[0070] (1) The collected microsilica powder was blown at a wind speed of 20 m / s and a wind volume of 65 m 3 / h under the condition of air separation and purification, light impurities are separated to obtain micro silicon powder 1;

[0071] (2) The microsilica powder 1 obtained in step (1) is separated from ferromagnetic impurities by high gradient magnetic separation technology, with a magnetic field strength of 2T and a magnetic field gradient of 2*10 4 T / m, the suspension and ionized water are configured in a mass ratio of 1:50, the flow rate of the suspension is 0.1m / s, the temperature is 20°C, and the pH value is 8, and magnetic separation purification is performed to obtain microsilica powder 2;

[0072] (3) drying the microsilica powder 2 obtained in step (2) at a low temperature of 90° C., and automatically adjusting the degree of drying by a humidity sensing system to obtain microsilica powder 3;

[0073] (4) sending the microsilica powder 3 obtained in step (3) into an airflow classification device for particle size separation under the conditions of an inlet airflow velocity of 20 m / s, an outlet airflow velocity of 10 m / s, a pressure in the classification chamber of 1000 Pa, and an angle of the guide blade of 15° to obtain microsilica powder 4;

[0074] (5) The microsilica powder 4 obtained in step (4) is subjected to high-temperature sintering at a temperature of 1000° C. using nitrogen as a protective gas for 4 hours and heat preservation for 1 hour to obtain microsilica powder 5;

[0075] (6) adding 1% hydrofluoric acid and 6 mol / L hydrochloric acid to the microsilica powder 5 obtained in step (5), acid leaching the silicon powder at a liquid-to-solid ratio of 25:1 and an acid leaching temperature of 85° C. for 2 hours, and drying the silicon powder in a drying oven at 90° C. for 24 hours to obtain microsilica powder 6;

[0076] (7) Slowly cooling the microsilica powder 6 obtained in step (6) for 6 hours to obtain microsilica powder 7;

[0077] (8) The microsilica powder 7 obtained in step (7) is crushed by a crushing device, and then, a multi-stage screening technology is used to accurately classify it according to the particle size to obtain microsilica powder L-2 of different particle sizes.

[0078] Example 3 A method for recycling microsilicon powder in the process of ferrosilicon production

[0079] The only difference from Example 1 is that the magnetic field intensity in step (2) is 1.0 T. The remaining steps are the same as in Example 1 to obtain microsilica powder L-3.

[0080] Example 4 A method for recycling microsilicon powder in the production process of ferrosilicon

[0081] The only difference from Example 1 is that the acid leaching time in step (6) is 1 hour. The remaining steps are the same as in Example 1 to obtain microsilica powder L-4.

[0082] Example 5 A method for recycling microsilicon powder in the process of ferrosilicon production

[0083] The only difference from Example 1 is that the acid leaching time in step (6) is 3 hours. The remaining steps are the same as in Example 1 to obtain microsilica powder L-5.

[0084] Example 6 A method for recycling microsilicon powder in the production process of ferrosilicon

[0085] The only difference from Example 1 is that the acid leaching in step (6) uses high-temperature sulfuric acid at a temperature of 100° C. and a concentration of 5%, a liquid-to-solid ratio of 10:1, and an acid leaching time of 1 hour. The remaining steps are the same as in Example 1 to obtain microsilica powder L-6.

[0086] Example 7 A method for recycling microsilicon powder in the production process of ferrosilicon

[0087] The only difference from Example 6 is that the acid leaching time in step (6) is 2 hours. The remaining steps are the same as Example 6 to obtain microsilica powder L-7.

[0088] Example 8 A method for recycling microsilicon powder in the production process of ferrosilicon

[0089] The only difference from Example 6 is that the acid leaching time in step (6) is 3 hours. The remaining steps are the same as Example 6 to obtain microsilica powder L-8.

[0090] Comparative Example 1 A method for recycling microsilicon powder in the production process of ferrosilicon

[0091] The only difference from Example 1 is that the magnetic field intensity in step (2) is 4 T. The remaining steps are the same as in Example 1 to obtain microsilica powder L-9.

[0092] Comparative Example 2 A method for recycling microsilicon powder in ferrosilicon production process

[0093] The only difference from Example 1 is that the magnetic field intensity in step (2) is 0.2 T. The remaining steps are the same as in Example 1 to obtain microsilica powder L-10.

[0094] Comparative Example 3 A method for recycling microsilicon powder in the production process of ferrosilicon

[0095] The only difference from Example 1 is that the acid leaching time in step (6) is 5 hours. The remaining steps are the same as in Example 1 to obtain microsilica powder L-11.

[0096] Comparative Example 4: A method for recycling microsilicon powder in ferrosilicon production

[0097] The only difference from Example 1 is that the acid leaching time in step (6) is 0.5 h. The remaining steps are the same as in Example 1 to obtain microsilica powder L-12.

[0098] Technical Effects

[0099] The results of measuring the content of each component in the microsilica powder obtained in Examples 1-8 are shown in Tables 1 and 2.

[0100] Table 1 Content of each component in microsilica powder

[0101]

[0102] Table 2 Content of each component in microsilica powder

[0103] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[SiO2]]> 94.33 93.88 94.42 94.24 <![CDATA[Fe2O3]]> 0.55 0.57 0.49 0.41 <![CDATA[Al2O3]]> 0.65 0.67 0.57 0.68 CaO 0.47 0.61 0.51 0.59 MgO 0.75 0.85 0.71 0.83 <![CDATA[K2O]]> 1.56 1.63 1.57 1.64 C 1.69 1.79 1.73 1.61

[0104] It can be seen from Examples 1-3 that the contents of the main component SiO2 of the microsilica powder after impurity removal and purification at three different magnetic field intensities are 99.04%, 99.08% and 98.67% respectively, which indicates that the silicon dioxide content in the microsilica powder is significantly increased under the action of acid leaching after magnetic separation. This is because the mixing of HF and HCl will act synergistically during the acid leaching process, and 1% HF can continue to react with the microsilica powder when HCl acts, causing porosity, thereby promoting the reaction of HCl.

[0105] It can be seen from Examples 1, 4 and 5 that different acid leaching times are used to remove impurities from microsilica powder, and the contents of its main component SiO2 are 99.04%, 96.52% and 95.44% respectively. It is found that the silica content in Example 4 decreases. This is because some microsilica powder particles cannot fully react with HF and HCl in the acid leaching solution, and the reaction time needs to be delayed. The silica content in Example 5 decreases. This is because the microsilica powder stays in the acid leaching volume for too long, resulting in side reactions. SiO2 participates in the reaction to generate insoluble substances, which are wrapped on the surface of the microsilica powder particles, thereby hindering the reaction of the microsilica powder and reducing the impurity removal rate.

[0106] It can be seen from Example 1 and Examples 6-8 that different acid leaching solutions remove impurities from microsilica powder, and the contents of its main component SiO2 are 99.04%, 97.59%, and 95.52%, respectively. It is found that the silicon dioxide content of Examples 6-8 has decreased. This is because the use of high-temperature sulfuric acid leaching mainly converts the metal oxides present in the microsilica powder into sulfate form, thereby destroying the impermeable layer and making the reactant particles more active, and finally causing certain metals to dissolve into the solution phase. According to the principle of chemical reaction equilibrium, during the acid leaching process, the concentration of the reaction product is reduced and the chemical reaction moves in the positive reaction direction. In other words, by increasing the temperature of sulfuric acid leaching, the reaction can be promoted in the positive reaction direction, further improving the utilization of sulfuric acid, allowing more metal oxide impurities to enter the acid solution, and obtaining higher purity silicon dioxide. The main reactions are as follows:

[0107] K2O+H2SO4=K2SO4+H2O

[0108] Al2O3+H2SO4=Al2(SO4)3+3H2O

[0109] MgO+H2SO4=MgSO4+H2O

[0110] CaO+H2SO4=CaSO4+H2O

[0111] Fe2O3+H2SO4=Fe2(SO4)3+H2O

[0112] Because some metal oxides are removed from the silicon micropowder after magnetic separation, the sulfuric acid solution cannot fully react with the metal oxides to form sulfates, resulting in a decrease in the silicon dioxide content.

[0113] It can be seen from Comparative Examples 1-4 that, with the change of magnetic field intensity and acid leaching time, the content of silicon dioxide is far less than that of the examples of the present invention.

[0114] It can be seen that only by adopting the conditions of the present invention can microsilica powder with higher purity be obtained.

Claims

1. A method for recycling microsilicon powder in a ferrosilicon production process, characterized in that: The following steps are involved: (1) Purifying the collected microsilica powder by air separation to separate light impurities to obtain microsilica powder 1; (2) purifying the microsilica powder 1 obtained in step (1) by magnetic separation to separate ferromagnetic impurities to obtain microsilica powder 2; (3) drying the microsilica powder 2 obtained in step (2) at low temperature to obtain microsilica powder 3; (4) sending the microsilica powder 3 obtained in step (3) into an air flow classification device for particle size separation to obtain microsilica powder 4; (5) sintering the microsilica powder 4 obtained in step (4) at high temperature to obtain microsilica powder 5; (6) acid-washing, acid-leaching, and drying the microsilica powder 5 obtained in step (5) to obtain microsilica powder 6; (7) cooling the microsilica powder 6 obtained in step (6) to obtain microsilica powder 7; (8) The microsilica powder 7 obtained in step (7) is crushed and sieved to obtain microsilica powder of different particle sizes.

2. The method according to claim 1, characterized in that: The wind separation equipment used in step (1) is wind separation equipment with a wind speed of 10m / s-20m / s and a wind volume of 65-75m 3 / h.

3. The method according to claim 1, characterized in that: The magnetic separation purification described in step (2) uses a strong magnetic field device and a high gradient magnetic separation technology. The magnetic field strength is 1-2T and the magnetic field gradient is 2*10 4 T / m, the solid mass fraction of the suspension is between 1%-5%, the flow rate should be 0.1-0.5m / s, the temperature is 20℃-25℃, and the pH value is controlled at 6-8.

4. The method according to claim 1, characterized in that: The temperature of the low-temperature drying in step (3) is 50°C-90°C.

5. The method according to claim 1, characterized in that: The inlet air flow velocity of the air flow classification equipment described in step (4) is 10m / s-20m / s, the outlet air flow velocity is 5m / s-10m / s, the pressure difference in the classification chamber is 500Pa-1000Pa, and the angle of the guide vane is 10°-15°.

6. The method according to claim 1, characterized in that: The protective atmosphere selected for the high-temperature sintering in step (5) is one of argon, nitrogen or other inert gases; the temperature range of the temperature-controlled sintering used in the high-temperature sintering is 800°C-1000°C, and the time is 2-4h.

7. The method according to claim 1, characterized in that: The acid used for pickling in step (6) is at least one of hydrofluoric acid, hydrochloric acid or sulfuric acid; the liquid-to-solid ratio of acid to silicon powder in the pickling is 10-25:1; the temperature of the pickling is 75°C-85°C, and the time of the pickling is 1-3h; the drying is carried out in a drying oven at 90°C for 24 hours.

8. The method according to claim 1, characterized in that: The cooling treatment in step (7) adopts slow cooling, and the cooling time is 4-6h.

9. The method according to claim 1, characterized in that: The crushing and screening in step (8) is carried out by crushing with a crushing device and screening is carried out using a multi-stage screening technology.

10. Use of microsilica powder recovered by the method described in any one of claims 1 to 9 in the preparation of high-end materials.

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