Method for preparing high-purity quartz sand from weakly magnetic mineral-containing quartzite

Abstract

This invention discloses a method for preparing high-purity quartz sand using quartzite containing weakly magnetic minerals as raw material. The method includes: grinding, screening, magnetic separation, and the following staged flotation: 1. Under conditions of pH 10-11, a first-stage flotation is performed using butyl xanthate as a collector to remove pyrite; 2. Under conditions of pH 5.0-5.5, a second-stage flotation is performed using styrene phosphonic acid as a collector to remove rutile; 3. Under conditions of pH 6.5-7.0, a third-stage flotation is performed using etheramine GE-609 as a collector to remove epidote; 4. Under conditions of pH 4.0-4.5, a fourth-stage flotation is performed using dodecylamine hydrochloride as a collector to remove garnet; finally, acid leaching, washing, and drying are performed to obtain the final quartz concentrate. This invention can effectively remove weakly magnetic mineral impurities, preparing high-purity quartz sand with a purity of up to 4N7, and with deep purification technology, it can reach 4N8.

Description

Technical Field

[0001] This invention relates to a method for preparing high-purity quartz sand, and more particularly to a method for preparing high-purity quartz sand using quartzite containing weakly magnetic minerals as raw material, belonging to the field of mineral processing technology. Background Technology

[0002] Quartzite is a metamorphic rock formed from quartz sandstone or other siliceous rocks through regional metamorphism or thermal contact metamorphism. my country has abundant quartzite resources and large-scale development and utilization. However, this type of quartz ore generally contains many impurities and is difficult to purify. Its industrial applications are mainly concentrated on low-value-added metallic silicon and ferrosilicon raw materials, as well as quartz raw material products with ω(SiO2) content of around 99%, which are not affected by grain size and angularity factors. Recent studies on the purification, testing, and evaluation of quartzite ore have revealed that some quartzites can be purified to high-purity quartz of 3N or higher, and some even have the potential to be purified and processed into high-end products of 4N8 high-purity quartz. Its industrial application scope and value have been severely underestimated.

[0003] Currently, quartzite produced in most parts of my country contains a large number of strongly magnetic and weakly magnetic impurities. Strongly magnetic impurities can be removed by magnetic separation, but weakly magnetic impurities (mainly including pyrite, rutile, epidote, and garnet) are more difficult to remove and require separation by flotation. Because quartz and weakly magnetic minerals have similar surface chemical properties, both primarily composed of silicon-oxygen bonds or metal-oxygen bonds, traditional collectors lack selectivity, especially in the presence of unavoidable ions (Ca). 2+ Mg 2+ Under interference, quartz is easily non-selectively activated, making effective separation difficult. The pH of the pulp significantly affects the flotation process. While pyrite can be effectively removed using a single alkaline flotation method, the removal rate of epidote is low, and rutile and garnet are almost not separated. The optimal flotation pH ranges for weakly magnetic minerals and quartz often overlap, resulting in a narrow pH control window. Non-selective adsorption by the collector leads to quartz entrainment and low recovery rates, failing to meet the requirements for high-purity quartz sand purification. When multiple impurities coexist, a single flotation reagent or flotation condition is insufficient, necessitating multiple flotation processes, resulting in severe cross-interference between reagents. Therefore, obtaining high-quality quartz sand from quartzite containing weakly magnetic minerals is quite challenging.

[0004] Currently, in the field of quartz sand purification, traditional purification processes are commonly used to purify different quartz ores. However, due to the types and forms of associated gangue minerals and inclusions in the quartz ores, as well as lattice impurities, stable production of high-purity quartz sand cannot be achieved. This is especially true for quartz sand purification processes using quartzite as the raw material, where each ore has its own unique process flow. In conventional flotation processes, most studies only consider impurities such as mica, feldspar, and iron oxides, without in-depth research on weakly magnetic minerals such as pyrite, rutile, epidote, and garnet. In particular, there are almost no reports on the separation of quartz-epidote and quartz-garnet from quartzite through flotation.

[0005] In summary, there is currently a gap in the technology for preparing high-purity quartz sand from quartzite containing weakly magnetic minerals. There is an urgent need to find a technology that can produce high-purity quartz sand from quartzite containing weakly magnetic minerals and is suitable for industrial mass production. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings of existing technologies in that it is difficult to effectively remove weakly magnetic minerals. This invention provides a method for preparing high-purity quartz sand using quartzite containing weakly magnetic minerals as raw material. Through a special staged flotation process combined with precise pH control, pyrite, rutile, epidote, and garnet can be effectively removed to prepare high-purity quartz sand with a purity of up to 4N7. With the addition of deep purification technology, the purity can reach 4N8.

[0007] The present invention specifically adopts the following technical solutions to solve the above-mentioned technical problems:

[0008] A method for preparing high-purity quartz sand using quartzite containing weakly magnetic minerals as raw material includes the following steps:

[0009] S1. Grind the raw quartzite ore to prepare quartz sand powder;

[0010] S2. The raw quartz sand ore powder is screened and classified to separate particles with a particle size of 80-160 mesh, thus obtaining pretreated ore powder.

[0011] S3. The pretreated mineral powder is subjected to magnetic separation to remove strongly magnetic impurities, resulting in magnetically separated quartz sand.

[0012] S4. The following staged flotation process is performed on the magnetically separated quartz sand ore:

[0013] S4-1. Under pH conditions of 10-11, butyl xanthate is used as a collector to carry out the first stage flotation of magnetically separated quartz sand ore to remove pyrite.

[0014] S4-2. Under pH conditions of 5.0 to 5.5, styrene phosphonic acid is used as a collector to carry out the second stage flotation of magnetically separated quartz sand ore to remove rutile.

[0015] S4-3. Under pH conditions of 6.5-7.0, etheramine GE-609 was used as a collector to carry out the third stage flotation of magnetically separated quartz sand ore to remove epidote.

[0016] S4-4. Under pH conditions of 4.0 to 4.5, dodecylamine hydrochloride is used as a collector to carry out the fourth stage flotation of magnetically separated quartz sand ore to remove garnet.

[0017] S5. After acid leaching, the quartz sand concentrate obtained from the staged flotation is washed and dried to obtain the final quartz concentrate.

[0018] Preferably, the staged flotation further includes a water washing process between each stage of flotation.

[0019] Preferably, the first to fourth stages of flotation each include one roughing stage and two to four cleaning stages.

[0020] Preferably, in the first stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-80 g / t; the quartz depressant is water glass, with a dosage of 300-400 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0021] Preferably, in the second stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-70 g / t; the quartz depressant is sodium fluorosilicate and carboxymethyl cellulose, with dosages of 20-50 g / t respectively; and the frother is terpineol, with dosages of 10-20 g / t.

[0022] Preferably, in the third stage flotation, the pulp mass concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0023] Preferably, in the fourth stage flotation, the pulp mass concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0024] More preferably, in the fourth stage of flotation, oxalic acid at a dosage of 20-30 g / t is added as a garnet activator.

[0025] Preferably, the acid leaching is performed using a mixed acid solution composed of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid, wherein the concentration of hydrochloric acid is 3 mol / L, the concentration of sulfuric acid is 3 mol / L, the concentration of nitric acid is 1 mol / L, and the concentration of hydrofluoric acid is 2 mol / L; the liquid-to-solid ratio of the mixed acid to the quartz sand concentrate is 1:3; and the acid leaching temperature is 95°C.

[0026] Furthermore, the method for preparing high-purity quartz sand also includes:

[0027] S6. Deeply purify the quartz concentrate.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention uses quartzite containing weakly magnetic minerals as raw material and proposes a special staged flotation process to address the challenge of removing these minerals. Using targeted flotation collectors and precise pH control, pyrite, rutile, epidote, and garnet are sequentially removed by flotation. This effectively removes these weakly magnetic mineral impurities that are difficult to remove using traditional processes, ultimately producing high-purity quartz sand with a purity of up to 4N7. Further purification processes, such as high-temperature chlorination, can produce extremely high-purity quartz sand with a purity of 4N8. This invention significantly expands the range of raw materials available for high-purity quartz sand preparation, effectively reduces production costs, and provides a new process route for the optimized purification of quartzite containing weakly magnetic minerals. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process flow for the high-purity quartz sand preparation method of the present invention. Detailed Implementation

[0031] To address the challenge of removing weakly magnetic minerals from quartzite containing weakly magnetic minerals, this invention employs a special staged flotation process. This process uses targeted flotation collectors combined with precise pH control to sequentially remove pyrite, rutile, epidote, and garnet through flotation. This effectively removes these weakly magnetic mineral impurities that are difficult to remove using traditional methods, resulting in high-purity quartz sand.

[0032] To remove different weakly magnetic impurities, the pH of the quartz pulp needs to be controlled in stages, gradually adjusting from strongly alkaline to weakly acidic. Butyl xanthate, styrene phosphonic acid, etheramine GE-609, and dodecylamine hydrochloride are used as flotation collectors for pyrite, rutile, epidote, and garnet, respectively. The specific principles of these collectors are as follows:

[0033] The collector for pyrite is butyl xanthate. The flotation principle is that the thiocarbamate groups of butyl xanthate coordinate with the Fe atoms exposed on the pyrite surface. 2+They combine to form stable metal xanthates. The butyl chains of butyl xanthate extend outward to form a hydrophobic layer, reducing the hydrophilicity of the mineral surface and making it easier for bubbles to adhere and float.

[0034] Styrenicotinic acid is an effective rutile collector. Its structure contains a hydrophobic phenyl group and a strongly chelating phosphonic acid group. The phosphonic acid group coordinates with the Ti on the rutile surface through a double-cogwheel mechanism. 4+ The combination forms a stable five-membered ring chelate, while the phenyl group extends outward to form a hydrophobic layer, reducing the hydrophilicity of the mineral surface and significantly increasing the probability of bubble adhesion.

[0035] Etheramine GE-609, used as a collector for epidote, utilizes its synergistic effect of chemisorption to separate it from quartz. At pH 6-8, Fe2+ is exposed in the epidote crystal structure. 3+ / Al 3+ It can react with the amino group (-NH) of GE-609. 3+ The oxygen atoms in the ether bond form stable hydrogen bonds with the hydroxyl groups on the surface of epidote, which enhances the adsorption stability. At the same time, the long-chain alkyl groups in etheramine GE-609 form a dense hydrophobic film, which significantly improves the bubble adhesion efficiency.

[0036] The collector for garnet is dodecylamine hydrochloride. Under weakly acidic conditions, the surface of garnet becomes negatively charged due to the dissociation of silicon-oxygen tetrahedra. The cationic dodecylamine in dodecylamine hydrochloride is adsorbed onto the negatively charged region of the garnet surface through electrostatic attraction. The amine groups react with the Al groups on the surface. 3+ Hydrogen bonds or weak coordination bonds are formed to enhance the stability of adsorption. The long-chain alkyl groups in dodecylamine hydrochloride extend outward to form a dense hydrophobic layer, making it easy for bubbles to adhere and float.

[0037] The method for preparing high-purity quartz sand using weakly magnetic mineral-containing quartzite as raw material proposed in this invention, such as... Figure 1 As shown, the specific steps include:

[0038] S1. Grind the raw quartzite ore to prepare quartz sand powder;

[0039] S2. The raw quartz sand ore powder is screened and classified to separate particles with a particle size of 80-160 mesh, thus obtaining pretreated ore powder.

[0040] S3. The pretreated mineral powder is subjected to magnetic separation to remove strongly magnetic impurities, resulting in magnetically separated quartz sand.

[0041] S4. The following staged flotation process is performed on the magnetically separated quartz sand ore:

[0042] S4-1. Under pH conditions of 10-11, butyl xanthate is used as a collector to carry out the first stage flotation of magnetically separated quartz sand ore to remove pyrite.

[0043] S4-2. Under pH conditions of 5.0 to 5.5, styrene phosphonic acid is used as a collector to carry out the second stage flotation of magnetically separated quartz sand ore to remove rutile.

[0044] S4-3. Under pH conditions of 6.5-7.0, etheramine GE-609 was used as a collector to carry out the third stage flotation of magnetically separated quartz sand ore to remove epidote.

[0045] S4-4. Under pH conditions of 4.0 to 4.5, dodecylamine hydrochloride is used as a collector to carry out the fourth stage flotation of magnetically separated quartz sand ore to remove garnet.

[0046] S5. After acid leaching, the quartz sand concentrate obtained from the staged flotation is washed and dried to obtain the final quartz concentrate.

[0047] To remove residual reagents, ensure the effectiveness of pH control, and avoid the influence of reagent interactions on flotation, the staged flotation preferably includes a water washing process between each stage of flotation.

[0048] To further improve the flotation effect, multiple flotation processes can be adopted in each stage of flotation. Preferably, the first to fourth stages of flotation each include one roughing stage and two to four cleaning stages. A higher collector dosage is used in the roughing stage, while the collector dosage can be reduced as appropriate in the cleaning stage.

[0049] Preferably, in the first stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-80 g / t; the quartz depressant is water glass, with a dosage of 300-400 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0050] Preferably, in the second stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-70 g / t; the quartz depressant is sodium fluorosilicate and carboxymethyl cellulose, with dosages of 20-50 g / t respectively; and the frother is terpineol, with dosages of 10-20 g / t.

[0051] Preferably, in the third stage flotation, the pulp mass concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0052] Preferably, in the fourth stage flotation, the pulp mass concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

[0053] To further improve the flotation effect of garnet, and more preferably, oxalic acid at a dosage of 20-30 g / t is added as a garnet activator in the fourth stage of flotation.

[0054] Preferably, the acid leaching is performed using a mixed acid solution composed of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid, wherein the concentration of hydrochloric acid is 3 mol / L, the concentration of sulfuric acid is 3 mol / L, the concentration of nitric acid is 1 mol / L, and the concentration of hydrofluoric acid is 2 mol / L; the liquid-to-solid ratio of the mixed acid to the quartz sand concentrate is 1:3; and the acid leaching temperature is 95°C.

[0055] Furthermore, the method for preparing high-purity quartz sand also includes:

[0056] S6. Deeply purify the quartz concentrate.

[0057] To facilitate public understanding, the technical solution of the present invention will be described in detail below through a specific embodiment:

[0058] The raw material used in this embodiment is a weakly magnetic quartzite produced in Lianyungang, Jiangsu Province. The main mineral composition of this ore is 92.5% quartz, 1.2% pyrite, 0.8% rutile, 3.5% epidote, and 1.0% garnet. The specific process for preparing high-purity quartz sand using this raw material is as follows:

[0059] (1) Grinding: The raw ore is crushed into small particles by a jaw crusher and further ground by a rod mill for 5 minutes to produce quartz sand raw ore powder.

[0060] (2) Screening: The quartz sand raw ore powder obtained in step (1) is screened and classified using a sieve. The screening method is wet screening. Particles with a particle size of 80-160 mesh are screened out, accounting for about 45.8%, and pre-treated ore powder is obtained.

[0061] (3) Magnetic separation: The quartz sand powder obtained in step (2) is magnetically separated by a strong magnetic rod to remove strong magnetic impurities and obtain magnetically separated quartz sand. The strength of the magnetic rod is 13000 Gauss and the magnetic separation time is 10-20 min.

[0062] (4) Removal of pyrite by flotation: The solid content of the pulp is controlled at 20%-30%. In the roughing operation, lime is added to the pulp to adjust the pH to 10.5; 70g / t of pyrite collector butyl xanthate is added; 350g / t of water glass as quartz inhibitor is added, and after stirring for 5min, 15g / t of frother terpineol is added. The mixture is aerated and skimmed, and the flotation time is 5-10min to obtain quartz rough concentrate. The rough concentrate is then cleaned twice. 25g / t of pyrite collector is added; 350g / t of water glass as quartz inhibitor is added, and after stirring for 5min, 15g / t of frother is added. The mixture is aerated and skimmed, and the flotation time is 5-10min.

[0063] (5) Removal of rutile by flotation: The quartz sand slurry obtained in step (4) is washed multiple times to remove residual reagents; an appropriate amount of water is added to adjust the slurry to a solid content of 20%-30%, and the pH of the quartz slurry is adjusted to 5.2 with sulfuric acid; during the roughing stage, 60 g / t of rutile collector styrene phosphonic acid, 40 g / t of quartz inhibitor sodium fluorosilicate, and 20 g / t of quartz inhibitor carboxymethyl cellulose are added, and after stirring for 5 min, 15 g / t of frother terpineol is added, and the flotation time is 5-10 min to obtain quartz rough concentrate; the rough concentrate is then subjected to two cleaning processes, with 20 g / t of rutile collector styrene phosphonic acid, 40 g / t of quartz inhibitor sodium fluorosilicate, and 20 g / t of quartz inhibitor carboxymethyl cellulose added, and after stirring for 5 min, 15 g / t of frother is added, and the flotation time is 5-10 min.

[0064] (6) Removal of epidote by flotation: The quartz sand slurry obtained in step (5) is washed multiple times to remove residual reagents; an appropriate amount of water is added to adjust the slurry, and the solid content of the slurry is controlled at 20%-30%, and the pH of the slurry is adjusted to 6.8; during the roughing stage, 50g / t of epidote collector etheramine GE-609 and 150g / t of quartz inhibitor water glass are added, and after stirring for 5 minutes, 15g / t of frother terpineol is added, and the slurry is aerated and skimmed. The flotation time is 5-10 minutes to obtain quartz rough concentrate; the rough concentrate is cleaned twice, and 20g / t of epidote collector etheramine GE-609 and 150g / t of quartz inhibitor water glass are added, and after stirring for 5 minutes, 15g / t of frother terpineol is added, and the slurry is aerated and skimmed. The flotation time is 5-10 minutes.

[0065] (7) Removal of garnet by flotation: The quartz sand slurry obtained in step (6) is washed multiple times to remove residual reagents; an appropriate amount of water is added to adjust the slurry, and the solid content of the slurry is controlled at 20%-30%. The pH of the slurry is adjusted to 4.3 with sulfuric acid; during the roughing stage, 50 g / t of dodecylamine hydrochloride, 25 g / t of oxalic acid, and 150 g / t of water glass are added as garnet collectors. After stirring for 5 min, 15 g / t of terpineol is added as frother. The flotation time is 5-10 min to obtain quartz rough concentrate; the rough concentrate is then treated twice. 20 g / t of dodecylamine hydrochloride, 25 g / t of oxalic acid, and 150 g / t of water glass are added as garnet collectors. After stirring for 5 min, 15 g / t of frother is added. The flotation time is 5-10 min.

[0066] (8) Acid leaching: After thoroughly washing the quartz sand concentrate obtained from flotation in step (7), transfer it to a container made of polytetrafluoroethylene. Add a mixed acid solution at a liquid-to-solid ratio of 1:3. The mixed acid is a mixture of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid solutions. The molar concentration of hydrochloric acid is 3 mol / L, the molar concentration of sulfuric acid is 3 mol / L, the molar concentration of nitric acid is 1 mol / L, and the molar concentration of hydrofluoric acid is 2 mol / L. The acid leaching temperature is 95℃ and the time is 6 hours. After acid leaching, wash it with ultrapure water until neutral and dry it to obtain the final quartz concentrate.

[0067] The final quartz sand concentrate was analyzed by HR ICP-MS to determine the content of impurity elements. The specific contents of impurity elements are shown in Table 1. The sum of the contents of impurity elements is less than 30 ppm, and the SiO2 content reaches 99.997%, which belongs to the mid-to-high-end high-purity quartz sand product.

[0068] Table 1. Impurity element content of high-purity quartz sand (10) -6

[0069] element Li Na Mg Al P K Ca Ti Cr content 0.99 2.02 0.3 12.6 0.061 0.041 1.14 5.42 <0 element Mn Fe Co Ni Cu Zn ∑ <![CDATA[SiO2(%)]]> purity content 0.097 6.45 <0 <0 0.26 0.12 29.499 99.997 4N7

[0070] The high-purity quartz sand prepared by the above process can achieve a purity of 4N8 after further deep purification treatment through high-temperature chlorination, fluoride complexation purification, microbial leaching, and supercritical fluid extraction, thus meeting the high-end application requirements in photovoltaics, electric light sources, and optical communications. Therefore, the technical solution of this invention is of great significance for improving the domestic production rate of high-end, high-purity quartz sand and reducing the import ratio.

Claims

1. A method for preparing high-purity quartz sand using quartzite containing weakly magnetic minerals as raw material, characterized in that, Includes the following steps: S1. Grind the raw quartzite ore to prepare quartz sand powder; S2. The raw quartz sand ore powder is screened and classified to separate particles with a particle size of 80-160 mesh, thus obtaining pretreated ore powder. S3. Magnetic separation is performed on the pretreated mineral powder to remove strongly magnetic impurities, resulting in magnetically separated quartz sand. S4. The following staged flotation process is performed on the magnetically separated quartz sand ore: S4-1. Under pH conditions of 10-11, butyl xanthate is used as a collector to carry out the first stage flotation of magnetically separated quartz sand ore to remove pyrite. S4-2. Under pH conditions of 5.0~5.5, styrene phosphonic acid is used as a collector to carry out a second-stage flotation of the magnetically separated quartz sand ore obtained in step S4-1 to remove rutile. S4-3. Under pH conditions of 6.5~7.0, using etheramine GE-609 as a collector, the magnetically separated quartz sand ore obtained in step S4-2 is subjected to a third-stage flotation to remove epidote. S4-4. Under pH conditions of 4.0~4.5, dodecylamine hydrochloride is used as a collector to carry out the fourth stage flotation of the magnetically separated quartz sand ore obtained in step S4-3 to remove garnet. S5. After acid leaching, the quartz sand concentrate obtained from the staged flotation is washed and dried to obtain the final quartz concentrate.

2. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, The staged flotation also includes a water washing process between each stage of flotation.

3. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, The first to fourth stages of flotation each consist of one roughing stage and two to four cleaning stages.

4. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, In the first stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-80 g / t; the quartz depressant is water glass, with a dosage of 300-400 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

5. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, In the second stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-70 g / t; the quartz depressant is sodium fluorosilicate and carboxymethyl cellulose, both at a dosage of 20-50 g / t; and the frother is terpineol at a dosage of 10-20 g / t.

6. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, In the third stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

7. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, In the fourth stage of flotation, the pulp concentration is 20%-30%; the collector dosage is 20-60 g / t; the quartz depressant is water glass, with a dosage of 150-200 g / t; and the frother is terpineol, with a dosage of 10-20 g / t.

8. The method for preparing high-purity quartz sand as described in claim 7, characterized in that, In the fourth stage of flotation, oxalic acid at a dosage of 20-30 g / t is added as a garnet activator.

9. The method for preparing high-purity quartz sand as described in claim 1, characterized in that, The acid leaching is performed using a mixed acid solution consisting of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid, wherein the concentrations of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid are 3 mol / L, 3 mol / L, 1 mol / L, and 2 mol / L.

10. The method for preparing high-purity quartz sand according to any one of claims 1 to 9, characterized in that, Also includes: S6. Deeply purify the quartz concentrate.

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