A microwave-conductivity-assisted flotation method and its application in quartz sand purification

Abstract

The present invention discloses a microwave-conductivity-assisted flotation method and its application in quartz sand purification. The microwave-conductivity-assisted flotation method comprises: partially or completely immersing the cathode and anode electrodes in a quartz sand slurry within a flotation machine and maintaining power; then, while stirring, adding a flotation agent to the quartz sand slurry and turning on the microwave. After a period of operation, the microwave is turned off, the cathode and anode electrodes are disconnected and removed, stirring is maintained, and flotation is performed with aeration. The present invention combines microwaves, conductivity, and flotation processes, particularly flotation agents, to achieve the purpose of deeply purifying alkali metal impurities in quartz sand.

Description

Technical Field

[0001] The present invention relates to the technical field of quartz sand processing, and in particular to a microwave-conductivity assisted flotation method and application thereof in quartz sand purification. Background Art

[0002] High-purity quartz sand is a key foundational material in numerous high-end industries, and its purity directly determines the performance and quality of the products it produces. From semiconductor chip manufacturing to the optical communications industry, from solar photovoltaics to the production of high-end optical instruments, high-purity quartz sand plays an indispensable role. Alkali metal impurities (such as Li, Na, and K), a key indicator of high-purity quartz sand quality, significantly impact its performance and applications. At high temperatures, alkali metals can reduce the thermal stability and melting point of quartz sand and its products, impair photoelectric properties, and reduce chemical stability. The semiconductor industry, in particular, places extremely high demands on the alkali metal content of high-purity quartz sand and its products.

[0003] As semiconductor technology requirements increase, so too do the demands for high-purity quartz sand. Whether it's semiconductor-grade high-purity quartz sand or the inner layer of photovoltaic crucible sand, it's crucial to avoid heavy reliance on imports and achieve independent supply of raw material ore resources. To this end, developing more efficient high-purity quartz sand purification processes and conducting in-depth technological upgrades are crucial to breaking the technological monopoly.

[0004] Flotation is a mineral processing method that utilizes differences in the physical and chemical properties of mineral surfaces to selectively separate particles at the gas-liquid-solid interface. Its core principle is to use bubbles to carry target mineral particles to the surface of the slurry, thereby separating useful minerals from gangue minerals.

[0005] In the high-purity quartz sand purification process, flotation has become an indispensable and important link due to its efficient resource utilization, fine sorting, adaptability to complex ores, controllable adsorption capacity and easy operation.

[0006] Traditional flotation processes rely on agitation to increase contact between reagent molecules and the mineral surface. However, the reagents used in flotation are often surfactants with long hydrophobic chains. Due to their hydrophobic nature, agitation alone cannot ensure sufficient contact between the reagent and the mineral surface, resulting in reduced reagent utilization and reduced flotation efficiency. In the field of high-purity quartz sand purification, in particular, due to the higher impurity removal rate requirements, traditional agitation flotation processes cannot meet practical needs, necessitating the development of other flotation processes supplemented by other means to improve quartz sand purification efficiency.

[0007] After searching, the following prior art is available:

[0008] 1) Use high-temperature chlorination (the main process at this stage) to remove alkali metal impurities.

[0009] Patent specification with publication number CN108910897A discloses a high-temperature activation and purification method for quartz sand, which removes alkali metal and alkaline earth metal impurities in the quartz sand by reacting the quartz sand with chlorinated gas for 15-120 minutes while swinging around an axis in a sealed furnace at 950-1450°C.

[0010] Patent specification with publication number CN117985725A discloses a treatment method for quartz sand suspension chlorination roasting purification. The method realizes the heating, chlorination reaction and cooling of quartz sand in stages through preheating and multi-stage suspension roasting. The products in each stage are controllable and adjustable, thereby removing impurities such as alkali metals and alkaline earth metals on the surface of quartz sand as much as possible to improve the purity of quartz sand.

[0011] 2) Use other methods to remove alkali metal impurities.

[0012] The patent specification with publication number CN115321544A discloses an ultrasonic vibration-electroadsorption cleaning method and purification process for high-purity quartz sand. It uses ultrasonic vibration to assist in separating metal ions and charged particles on the surface of quartz sand. At the same time, it uses electroadsorption technology to adsorb metal ions, charged particles, etc. in the solution onto electrodes on both sides, thereby achieving the purpose of efficiently removing impurities attached to the surface of high-purity quartz sand, and solving the problem that impurity residues in the existing quartz sand purification process make it difficult to improve the purity of quartz sand.

[0013] Patent specification CN117819556A discloses a method for preparing high-purity quartz using high-alkalinity activation as an aid. The method first uses calcined water quenching to create cracks in quartz sand, opening up channels in the quartz sand. The quartz sand is then activated using high-strength alkali, destroying the quartz lattice structure and converting impurities within the lattice into an easily removable free state. The exposed lattice impurities are then removed using high-temperature acid leaching, thereby achieving the purpose of removing impurity elements, especially alkali metal sodium.

[0014] Patent specification with publication number CN119019089A discloses a method for preparing low-hydroxyl, low-alkali metal high-purity quartz sand, which includes crushing and sand making, flotation using hydrofluoric acid (HF) as a pH adjuster and activator, and dodecylamine as a collector; then oxidative pickling and impurity removal using a composite acid solution composed of HF and ferrate; the quartz raw material after oxidative pickling and impurity removal is mixed with carbon powder and calcined at a high temperature of 1100-1350°C; pickling and impurity removal of the obtained quartz raw material using a composite acid solution composed of a halogen acid and a heavy metal chelating agent, and washing and drying after pickling to obtain low-hydroxyl, low-alkali metal high-purity quartz sand.

[0015] Existing processes for removing alkali metal impurities often require the use of high-risk gases such as hydrogen chloride in high-temperature chlorination, chlorine and other chlorides, or the use of strong bases or strong acids (such as hydrofluoric acid) for auxiliary purification. Since these are high-risk chemicals, their storage and transportation have strict requirements. During long-term use, they will not only corrode equipment but also pose safety risks such as leakage and personal injury, and increase the company's production costs.

[0016] Simply using electrosorption to adsorb metal ions and charged particles from a solution onto electrodes on either side to purify metal impurities has limited effectiveness. Because quartz sand has poor electrical conductivity, relying on its electrical properties to migrate through water is often only effective for free metal impurities or those easily removed from the quartz surface. It is ineffective for deeply removing alkali metal impurities. Summary of the Invention

[0017] In order to solve the above technical problems and the shortcomings in the field, the present invention provides a microwave-conductivity assisted flotation method and its application, which can remove alkali metal impurities in quartz sand in a deep way without using high temperature and high-risk chemical reagents. Figure 1 Specific measures include:

[0018] By using microwave-assisted flotation, microwaves are used to increase the rapid movement of reagents in water, thereby increasing their water solubility and making the slurry system more uniform. At the same time, it also increases the contact opportunities between reagent molecules and alkali metal impurities in the minerals, thereby improving flotation efficiency.

[0019] Through conductivity-assisted flotation, alkali metal impurities in quartz sand that has been pretreated by roasting are prone to lose electrons under the influence of external current / electric field, and transfer charges along microcracks or the quartz surface, thereby presenting different positive and negative charge areas on the quartz surface; under the assistance of microwaves, the reagent molecules are adsorbed on the new charge areas on the quartz surface through electrostatic action, thereby achieving the purpose of deep purification.

[0020] The specific technical solutions are as follows:

[0021] In a first aspect, the present invention provides a microwave-conductivity-assisted flotation method, comprising: partially or completely immersing the cathode and anode electrode plates in a quartz sand slurry in a flotation machine and keeping them powered on, then adding a flotation agent to the quartz sand slurry under stirring and turning on the microwave, turning off the microwave after running for a period of time, removing the cathode and anode electrode plates without power, maintaining stirring, and aerating for flotation.

[0022] Preferably, in the microwave-conductivity assisted flotation method, the stirring speed is 1500-2000 r / min.

[0023] Preferably, in the microwave-conductivity assisted flotation method, the frequency of the microwave is 2-2.45 GHz.

[0024] Preferably, in the microwave-conductivity-assisted flotation method, direct current is applied to the cathode and anode electrodes. Further preferably, the direct current voltage is 100-220 V.

[0025] Preferably, the microwave-conductivity assisted flotation method has an operating time of 15 to 35 minutes, such as 20 minutes, 25 minutes, 30 minutes, etc.

[0026] Preferably, the microwave-conductivity assisted flotation method is reverse flotation.

[0027] Preferably, in the microwave-conductivity assisted flotation method, the flotation agent includes at least one of a cationic collector and a chelating agent.

[0028] Furthermore, the cationic collector may include one or more of dodecylamine, hexadecylamine, octadecylamine, and the like.

[0029] Furthermore, based on the mass of the quartz sand in the quartz sand slurry, the amount of the cationic collector added is 20-25 g / 500 kg.

[0030] Furthermore, the chelating agent may include a crown ether compound. Furthermore, the crown ether compound may include one or more of 18-crown-6, 15-crown-5, 12-crown-4, etc. For alkali metal impurities, the present invention particularly uses a crown ether compound chelating agent.

[0031] Furthermore, based on the mass of the quartz sand in the quartz sand slurry, the amount of the chelating agent added is 40-50 g / 500 kg.

[0032] In a second aspect, the present invention provides the use of the microwave-conductivity-assisted flotation method described in the first aspect for quartz sand purification. The microwave-conductivity-assisted flotation method can be used to purify high-purity quartz sand (silicon dioxide content of 99.999 wt% or greater). The microwave-conductivity-assisted flotation method can be used to separate at least alkali metal impurities from the quartz sand. These alkali metal impurities may include one or more of lithium, sodium, potassium, and the like.

[0033] In a third aspect, the present invention provides a purification process for high-purity quartz sand, comprising the steps of:

[0034] S01: Crushing ore;

[0035] S02: color sorting;

[0036] S03: roasting and water quenching;

[0037] S04: magnetic separation;

[0038] S05: first flotation;

[0039] S06: acid leaching;

[0040] S07: performing a second flotation using the microwave-conductivity assisted flotation method described in the first aspect to obtain high-purity quartz sand.

[0041] Preferably, in step S01, the particle size of the crushed ore is 1-3 cm.

[0042] Preferably, in step S02, a color sorter is used to remove impurities from the crushed non-ferrous ore using a laser light source.

[0043] Preferably, in step S03, the roasting temperature is 600-800°C, the roasting time is 2-4 hours, and the sand is made into 60-180 mesh particles after water quenching.

[0044] Preferably, in step S04, an electromagnetic separator is used, the background magnetic field strength of the electromagnetic separator is 5000-6000 GS, and the magnetic separation time is 2-4 h.

[0045] Preferably, in step S05, sulfuric acid is used as a pH regulator in the first flotation, dodecylamine and sodium dodecylsulfonate are used as collectors, and the pH of the first flotation is 2-3.

[0046] Preferably, in step S06, the acid used for acid leaching is a mixture of sulfuric acid, hydrochloric acid, and hydrofluoric acid, the acid leaching temperature is 80-100° C., and the acid leaching time is 6-8 h.

[0047] In step S07, the mass content of SiO2 in the obtained high-purity quartz sand is above 99.999%, and the mass content of alkali metal impurities is less than 1 ppm.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. Deep Removal of Alkali Metal Impurities: Microwave-assisted flotation accelerates the molecular motion of reagent molecules in the slurry, making them more evenly distributed throughout the system and improving flotation efficiency. Conductivity-assisted flotation utilizes a stable current / electric field to induce charge migration within the alkali metal impurities within the quartz sand, exposing more charged areas on the quartz surface, which facilitates interaction with the reagent. The combination of microwaves, conductivity, and flotation processes, particularly flotation reagents, achieves the goal of deep purification of alkali metal impurities in quartz sand.

[0050] 2. The flotation purification process is green and environmentally friendly: Compared with the traditional process of deep removal of alkali metal impurities, this combined process does not use highly dangerous chemicals or strong acids and alkalis, thus avoiding corrosion to equipment, environmental pollution and potential safety threats to personnel, reducing enterprise operating costs and improving enterprise benefits.

[0051] 3. The purification process of high-purity quartz sand of the present invention can obtain high-purity quartz sand products with a silicon dioxide (SiO2) content of more than 99.999wt% after the second flotation, without the need for high-temperature chlorination and other operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of the working principle of the microwave-conductivity assisted flotation method of the present invention.

[0053] Figure 2 This is a graph showing the results of the comprehensive mineral analysis data of quartz sand using TIMA (Tescan Integrated Mineral Analyzer) before and after microwave-conductivity assisted flotation in Example 1.

[0054] Figure 3 This is a graph showing the results of TIMA comprehensive mineral analysis data of quartz sand before and after microwave-conductivity assisted flotation in Example 2.

[0055] Figure 4 This is a graph showing the results of TIMA comprehensive mineral analysis data of quartz sand before and after microwave-conductivity assisted flotation in Example 3.

[0056] Figure 5 This is the TIMA comprehensive mineral analysis data test result of quartz sand after microwave-assisted flotation in comparative example 1. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0058] Example 1:

[0059] Raw ore material analysis: Taking a batch of granite pegmatite ore from a certain region in India as an example, the material analysis showed that the mass content of quartz in the raw ore was 57.88%, the mass content of feldspar was 21.79%, the mass content of mica was 18.44%, the mass content of hematite / magnetite was 1.29%, and the mass content of other impurity minerals such as rutile and ilmenite was less than 1%.

[0060] Pretreatment process: The raw ore is coarsely crushed using a crusher to obtain coarse ore with an average particle size of 1-3 cm. After coarse crushing, the ore with a particle size greater than 3 cm is returned to the crusher for further crushing; the coarse ore with an average particle size of 1-3 cm is color-sorted, and the color sorter uses a laser light source to remove the coarse ore with a large amount of colored impurities; the screened coarse ore is high-temperature roasted and water-quenched at a heating temperature of 600°C for 2 hours, and after water quenching, it is finely crushed into 60-180 mesh quartz sand particles; the obtained quartz sand particles are magnetically separated using an electromagnetic separator with a background magnetic field strength of 6000GS and a magnetic separation time of 2 hours to separate magnetic mineral impurities; the quartz sand after magnetic separation is flotated, and the pH is adjusted to 2 with sulfuric acid as an adjusting agent. 40 g / t of dodecylamine (t represents tons, measured by the mass of quartz sand in the ore pulp, the same below) and 40 g / t of sodium lauryl sulfate are added successively. g / t for flotation, and after flotation, rinsed with clean water three times and dried; the dried quartz sand was acid leached, the acid leaching solution was a mixture of sulfuric acid, hydrochloric acid and hydrofluoric acid in a volume ratio of 1:1:1, the dosage was 1000 L / t, the acid leaching temperature was 80℃, the acid leaching time was 6h, the quartz sand after acid leaching was rinsed with clean water three times and centrifuged and dried for use.

[0061] Microwave-conductivity-assisted flotation process: Using a reverse flotation process. 500 kg of dried quartz sand was poured into the flotation cell, and water was added to form a slurry. The water level in the cell was controlled. The cathode and anode electrodes were lowered below the liquid surface and powered on at a DC voltage of 100 V. The agitator was also started at a speed of 2000 rpm. After 20 minutes, 20 g of the cationic collector, dodecylamine, was added to the slurry. A microwave transmitter was also activated at a frequency of 2.45 GHz. Ten minutes later, 40 g of the crown ether chelating agent, 18-crown-6, was added. After stirring for 20 minutes, the microwave transmitter was turned off, power was removed, the cathode and anode electrodes were removed, and air was activated to begin flotation. The flotation foam flowed out of the flotation cell as the water level increased. After 20 minutes of flotation, the quartz sand was washed three times with clean water and dried to obtain the final product.

[0062] The test results show that the main content indicators of the quartz sand treated according to the above process parameters and conditions are shown in Table 1 below, where the SiO2 mass content (%) is determined by X-ray fluorescence spectrometry (XRF), and the alkali metal element content (ppm, one part per million by mass, the same below) is determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The quartz sand before microwave-conductivity-assisted flotation is the quartz sand that is acid-leached, rinsed with clean water, and dried. The quartz sand after microwave-conductivity-assisted flotation is the final finished sand, which will not be described in detail below.

[0063] Table 1

[0064]

[0065] The TIMA comprehensive mineral analysis data test results of quartz sand before and after microwave-conductivity assisted flotation are as follows: Figure 2 shown.

[0066] Comparing the above data reveals that microwave-conductivity-assisted flotation can deeply remove alkali metal impurities from quartz sand. After a single treatment, the alkali metal impurity content is less than 1 ppm, and the SiO2 content reaches over 99.999%. This not only effectively removes impurities on the surface of the quartz sand, but also has a significant effect on alkali metal impurities within the sand. The treated quartz sand can be used as crucible lining sand and semiconductor-grade quartz products.

[0067] Example 2:

[0068] The raw ore material analysis and pretreatment process were the same as in Example 1, that is, quartz sand obtained by pretreatment of the same batch of raw ore as in Example 1 was used.

[0069] Microwave-conductivity-assisted flotation process: The only difference from the microwave-conductivity-assisted flotation process in Example 1 is that the cationic collector is hexadecylamine and the crown ether chelating agent is 15-crown-5. The rest are the same, and finished sand is obtained.

[0070] The test results show that the main content indicators of the quartz sand treated according to the above process parameters and conditions are shown in Table 2 below.

[0071] Table 2

[0072]

[0073] The TIMA comprehensive mineral analysis data test results of quartz sand before and after microwave-conductivity assisted flotation are as follows: Figure 3 shown.

[0074] After comparing the above data, it was found that the flotation reagents using hexadecylamine as a cationic collector and 15-crown-5 as a chelating agent for flotation, combined with microwave-conductivity assistance, can deeply remove alkali metal impurity minerals mixed in quartz sand. After one treatment, the alkali metal impurity content is less than 1 ppm, and the SiO2 content reaches more than 99.999%.

[0075] Example 3:

[0076] The raw ore material analysis and pretreatment process were the same as in Example 1, that is, quartz sand obtained by pretreatment of the same batch of raw ore as in Example 1 was used.

[0077] Microwave-conductivity-assisted flotation process: The only difference from the microwave-conductivity-assisted flotation process in Example 1 is that the cationic collector is octadecylamine and the crown ether chelating agent is 12-crown-4. The rest are the same, and finished sand is obtained.

[0078] The test results show that the main content indicators of the quartz sand treated according to the above process parameters and conditions are shown in Table 3 below.

[0079] Table 3

[0080]

[0081] The TIMA comprehensive mineral analysis data test results of quartz sand before and after microwave-conductivity assisted flotation are as follows: Figure 4 shown.

[0082] After comparing the above data, it was found that the flotation agent using octadecylamine as a cationic collector and 12-crown-4 as a chelating agent for flotation, combined with microwave-conductivity assistance, can deeply remove alkali metal impurity minerals mixed in quartz sand. After one treatment, the alkali metal impurity content is less than 1 ppm, and the SiO2 content reaches more than 99.999%.

[0083] Comparative Example 1:

[0084] The raw ore material analysis and pretreatment process were the same as in Example 1, that is, quartz sand obtained by pretreatment of the same batch of raw ore as in Example 1 was used.

[0085] The microwave-conductivity-assisted flotation process differs from Example 1 only in that there is no conductivity assistance, and the rest are the same.

[0086] The test results show that the main content indicators of the quartz sand treated according to the above process parameters and conditions are shown in Table 4 below.

[0087] Table 4

[0088]

[0089] The TIMA comprehensive mineral analysis data of quartz sand after microwave assisted flotation is as follows Figure 5 shown.

[0090] After comparing the above data, it was found that microwave-assisted flotation can effectively remove alkali metal impurity minerals mixed in the outside of quartz sand. After one treatment, the alkali metal impurity content was reduced to about 10 ppm, and the SiO2 content reached 99.990%. However, it has basically no effect on removing impurities inside the quartz sand. The finished product after treatment cannot meet the requirements of photovoltaic inner layer sand and semiconductor-grade quartz products.

[0091] Comparative Example 2:

[0092] The raw ore material analysis and pretreatment process were the same as in Example 1, that is, quartz sand obtained by pretreatment of the same batch of raw ore as in Example 1 was used.

[0093] The microwave-conductivity assisted flotation process is the same as that of Example 1 except that there is no microwave assistance.

[0094] The test results show that the main content indicators of the quartz sand treated according to the above process parameters and conditions are shown in Table 5 below.

[0095] Table 5

[0096]

[0097] After comparing the above data, it was found that conductivity-assisted flotation can remove some alkali metal impurity minerals to a certain extent. After one treatment, the alkali metal impurity content was reduced to about 30 ppm, and the SiO2 content reached 99.982%. However, the removal efficiency of alkali metal impurities was low, and the finished product after treatment could not meet the requirements of photovoltaic inner layer sand and semiconductor-grade quartz products.

[0098] In summary, the present invention can deeply remove alkali metal impurities, not only removing alkali metal impurities on the quartz surface, but also having a significant removal effect on alkali metal impurities inside the quartz. Moreover, the flotation combined process is green and environmentally friendly, and does not use high-risk chemicals.

[0099] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A microwave-conductivity assisted flotation method, characterized in that: include: Immerse the cathode and anode plates partially or completely in the quartz sand slurry in the flotation machine and keep the power on. Then, add flotation reagents to the quartz sand slurry while stirring and turn on the microwave. After running for a period of time, turn off the microwave, remove the cathode and anode plates, keep stirring, and perform flotation with air. The flotation reagent includes a chelating agent; The chelating agent is a crown ether compound; the crown ether compound includes one or more of 18-crown-6, 15-crown-5, and 12-crown-4; Based on the mass of the quartz sand in the quartz sand slurry, the added amount of the chelating agent is 40-50 g / 500 kg.

2. The microwave-conductivity assisted flotation method according to claim 1, characterized in that: The stirring speed is 1500-2000 r / min; The frequency of the microwave is 2-2.45 GHz.

3. The microwave-conductivity assisted flotation method according to claim 1, characterized in that: The cathode and anode plates are supplied with direct current, and the DC voltage is 100~220 V.

4. The microwave-conductivity assisted flotation method according to claim 1, characterized in that: The running time is 15 to 35 minutes.

5. The microwave-conductivity assisted flotation method according to claim 1, characterized in that: The microwave-conductivity assisted flotation method is reverse flotation; The flotation reagent also includes a cationic collector; The cationic collector includes one or more of dodecylamine, hexadecylamine and octadecylamine; Based on the mass of the quartz sand in the quartz sand slurry, the added amount of the cationic collector is 20-25 g / 500 kg.

6. Use of the microwave-conductivity-assisted flotation method according to any one of claims 1 to 5 in quartz sand purification.

7. The use according to claim 6, characterized in that The microwave-conductivity assisted flotation method is used for purifying high-purity quartz sand; The microwave-conductivity assisted flotation method is at least used for separating alkali metal impurities in quartz sand.

8. The use according to claim 7, characterized in that The alkali metal impurities include one or more of lithium, sodium and potassium.

9. A purification process for high-purity quartz sand, characterized in that: Including steps: S01: Crushing ore; S02: Color sorting; S03: roasting and water quenching; S04: magnetic separation; S05: first flotation; S06: acid leaching; S07: Perform a second flotation using the microwave-conductivity assisted flotation method described in any one of claims 1 to 5 to obtain high-purity quartz sand.

10. The purification process of high-purity quartz sand according to claim 9, characterized in that: In step S01, the particle size of the ore after crushing is 1-3 cm; In step S02, a color sorter is used to remove impurities from the crushed non-ferrous ore using a laser light source; In step S03, the roasting temperature is 600-800°C, the roasting time is 2-4 hours, and the sand is made into 60-180 mesh particles after water quenching; In step S04, an electromagnetic separator is used, the background magnetic field strength of the electromagnetic separator is 5000-6000 GS, and the magnetic separation time is 2-4 hours; In step S05, sulfuric acid is used as a pH regulator in the first flotation, and dodecylamine and sodium dodecylsulfonate are used as collectors. The pH of the first flotation is 2-3. In step S06, the acid used for acid leaching is a mixture of sulfuric acid, hydrochloric acid, and hydrofluoric acid, the acid leaching temperature is 80-100°C, and the acid leaching time is 6-8 hours; In step S07, the mass content of SiO2 in the obtained high-purity quartz sand is above 99.999%, and the mass content of alkali metal impurities is less than 1 ppm.

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