A method for screening pegmatitic quartz potential raw materials and a method for preparing 4N8 grade high-purity quartz sand

Abstract

The application provides a pegmatite type quartz potential raw material screening method and a 4N8 grade high-purity quartz sand preparation method, and belongs to the technical field of mineral screening. The pegmatite type quartz potential raw material screening method comprises the following screening bases: a first screening basis and a second screening basis, i.e., detecting the characteristics of quartz inclusions in pegmatite geological inclusions; and a third screening basis, i.e., detecting the content of titanium elements in the pegmatite. When the sample to be screened meets the first screening basis and / or the second screening basis, the sample is determined as a preliminary potential sample, and then the preliminary potential sample is determined according to the third screening basis. The pegmatite type quartz potential raw material is determined as the sample meeting the third screening basis. The pegmatite geological inclusions can be used to quickly determine the potential sample, and the non-potential sample can be directly removed, so that the high-quality mineral resources can be quickly found.

Description

Technical Field

[0001] This invention relates to the field of mineral screening technology, and in particular to a screening method for pegmatite-type quartz potential raw materials and a method for preparing 4N8 grade high-purity quartz sand. Background Technology

[0002] High-purity quartz is an indispensable and irreplaceable functional material for industries such as semiconductors, optical fibers, photovoltaics, optics, and electric light sources, and is a scarce resource worldwide. In recent years, pegmatite-type quartz resources have become a new direction for finding high-purity quartz resources due to their advantages such as large scale, low impurities, stable quality, and low fluid inclusion content.

[0003] Existing mineral processing technologies, based on the physical and chemical properties of different minerals in the ore, involve crushing and grinding the ore, and then using methods such as gravity separation, flotation, magnetic separation, and electrostatic separation to separate valuable minerals from gangue minerals, and to separate various associated (symbiotic) valuable minerals as much as possible, removing or reducing harmful impurities to obtain raw materials needed for smelting or other industries. This process enriches the valuable components in the minerals, reduces fuel and transportation consumption during smelting or other processing, and allows for the economical utilization of low-grade ores. However, existing mineral processing technologies cannot pre-screen potential samples, resulting in slow and difficult exploration for high-purity quartz. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for screening potential raw materials of pegmatite-type quartz and a method for preparing 4N8 grade high-purity quartz sand. The screening method of this invention is fast and simple, enabling rapid identification of potential samples and direct rejection of non-potential samples, thereby achieving the goal of quickly finding high-quality mineral resources.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for screening potential raw materials of pegmatite-type quartz, comprising the following steps:

[0007] The first screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Quartz inclusions accounting for less than 5% of the quartz grain area and having a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers. Alternatively, quartz inclusions in which more than 70% are distributed at the edge of fractures or at different depths, and no more than 30% are distributed simultaneously at different depths, and having a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers.

[0008] The second screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Based on the quartz inclusions with a diameter of no more than 125 μm, the proportion of inclusions with a diameter of less than 1 μm in the quartz inclusions is less than 20%, which is used as a preliminary potential sample identifier.

[0009] The third screening criterion is to detect the titanium content in the pegmatite, with a titanium content ≤10ppm indicating a potential sample.

[0010] Once a sample to be screened meets the first screening criteria and / or the second screening criteria and is determined to be a preliminary potential sample, the preliminary potential sample is then judged according to the third screening criteria. The sample that meets the third screening criteria is the potential raw material of pegmatite-type quartz.

[0011] Preferably, the titanium content in the pegmatite is obtained by cathodic fluorescence spectroscopy (CL), and the titanium content ≤10ppm means that the spectral intensity at wavelengths of 350-500nm in the cathodic fluorescence spectrum is ≤100 counts.

[0012] Preferably, the following screening criteria are also included:

[0013] The fourth screening criterion is to determine the potential samples by observing the color of the quartz particles in the pegmatite. The color of the quartz particles is colorless and transparent or light smoky gray. The light smoky gray is Pantone Cool Gray 1C to 9C in the Pantone color chart.

[0014] The fifth screening criterion is to detect whether rare elements exist in the pegmatite mineralization belt, and to identify potential samples that do not contain rare metals.

[0015] The sixth screening criterion is to test the mineral composition of the pegmatite. Potential samples are identified by the bright color of the muscovite, the full lamellar structure, the garnet content not exceeding 2% by mass, and the absence of rutile.

[0016] The seventh screening criterion is to observe the mosaic characteristics of pegmatite geological thin sections, and to identify potential samples with loose bonding of quartz, feldspar, and mica, clear edges of the external shape of quartz, distinct separation of quartz, mica, and feldspar, and no mutual mosaic relationship.

[0017] The eighth screening criterion: observe the mineral composition of pegmatite geological thin sections, and identify potential samples with a reflectance of ≥60% at a wavelength of 550nm under a microscope, euhedral crystals, and a gray value of ≥200.

[0018] Ninth screening criterion: Observe the oil-immersed sections of pegmatite inclusions, and identify potential samples with an inclusion area of ​​less than 5% in the oil-immersed sections of pegmatite inclusions;

[0019] The tenth screening criterion: Detect the degree of cracking in the quartz particles within the pegmatite, and identify potential samples with a surface crack area ratio of ≤2% for the quartz particles;

[0020] Those that meet more than 5 of the fourth to tenth screening criteria are considered potential raw materials for pegmatite-type quartz.

[0021] Preferably, materials that meet the first to tenth screening criteria are considered as potential raw materials for pegmatite-type quartz.

[0022] Preferably, the rare elements include Li and Be.

[0023] This invention also provides a method for preparing 4N8 grade high-purity quartz sand, comprising the following steps:

[0024] Using the screening method described in the above technical solution, potential raw materials of pegmatite-type quartz are obtained;

[0025] The pegmatite-type quartz potential raw material is subjected to crushing, acid washing, weak magnetic separation, strong magnetic separation, flotation, roasting and water quenching, acid leaching, drying and chlorination purification in sequence to obtain the 4N8 grade high-purity quartz sand. The magnetic field strength of the weak magnetic separation is 0.1~0.5T and the magnetic field strength of the strong magnetic separation is 1.5~1.7T.

[0026] Preferably, the collector used in the flotation includes dodecylamine and octadecylamine, and the mass ratio of dodecylamine to octadecylamine in the collector is 1:1.5 to 2.

[0027] Preferably, the roasting temperature during roasting and water quenching is 1000-1500℃ and the time is 0.5-1h, and the water quenching temperature during roasting and water quenching is 50-80℃ and the time is 0.5-1min.

[0028] Preferably, the mixed acid used in the acid leaching includes concentrated hydrochloric acid, hydrofluoric acid, and concentrated nitric acid, wherein the mass concentration of the concentrated hydrochloric acid is 36% to 38%, the mass concentration of the concentrated nitric acid is 40% to 68%, the mass concentration of the hydrofluoric acid is 35% to 45%, and the volume ratio of the concentrated hydrochloric acid, hydrofluoric acid, and concentrated nitric acid in the mixed acid is 20:6:2.

[0029] Preferably, the chlorination purification is carried out at a temperature of 1000–1400°C for 0.5–1 hour, and the chlorination purification is performed in chlorine or hydrogen chloride gas.

[0030] This invention provides a method for screening potential raw materials of pegmatite-type quartz, comprising the following steps: First screening criterion: Detecting the characteristics of quartz inclusions in pegmatite geological inclusions, wherein the quartz inclusions occupy less than 5% of the quartz grain area and the volume ratio of the gas-liquid phase in the quartz inclusions is more than 80% as preliminary potential sample identifiers; or wherein more than 70% of the quartz inclusions are distributed at the edge of fractures or fractures, centers, and different depths simultaneously, and no more than 30% of the quartz inclusions are distributed at the same depth, and the volume ratio of the gas-liquid phase in the quartz inclusions is more than 80% as preliminary potential sample identifiers; Second screening criterion: Detecting pegmatite... The characteristics of quartz inclusions in geological inclusions are defined as follows: quartz inclusions with a diameter not exceeding 125 μm, and inclusions with a diameter less than 1 μm accounting for less than 20% of the total, are used as preliminary potential sample identifiers. The third screening criterion is the detection of titanium content in pegmatite, with titanium content ≤10 ppm used as a potential sample identifier. When a sample meets the first and / or second screening criteria and is determined to be a preliminary potential sample, the preliminary potential sample is further evaluated according to the third screening criteria. Samples meeting the third screening criteria are considered potential raw materials for pegmatite-type quartz.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention enables rapid identification of potential samples through pegmatite geological inclusions, allowing for the direct rejection of non-potential samples. This facilitates the rapid identification of high-quality mineral resources, avoiding unnecessary work (requiring time-consuming, labor-intensive, and expensive beneficiation and purification of each sample; compared to traditional direct beneficiation methods, the advantage of this method lies in screening and identifying raw materials before beneficiation). It also avoids the need for one-by-one processing in traditional beneficiation processes, significantly improving work efficiency and achieving the goal of quickly finding high-quality mineral resources. Furthermore, the screening method of this invention uses less raw material, allowing geological workers to collect a large number of different mineral samples in remote field locations.

[0033] The present invention also provides a method for preparing 4N8 grade high-purity quartz sand, which shortens the working time through screening method, and the preparation time is preferably no more than 28 hours, which greatly improves the work efficiency. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the preparation method and testing process of 4N8 grade high-purity quartz sand in Example 1 of this document;

[0035] Figure 2 Photographs of the specimen in Example 1;

[0036] Figures 3-7 These are polarized light microscope images of the rock and mineral thin sections at different positions and magnifications in Example 1;

[0037] Figure 8 The X-ray diffraction pattern of the pegmatite-type quartzite ore specimen in Example 1;

[0038] Figures 9-11 These are polarizing microscope images of 4N8 grade high-purity quartz sand at different magnifications in Example 1;

[0039] Figure 12 This is a photograph of the 4N8 grade high-purity quartz sand from Example 1.

[0040] Figures 13-17 These are polarizing microscope images of the rock and mineral thin sections at different positions and magnifications in Example 2. Figure 15 These are common polarized microscope images of the edges of cracks. Figure 16 This is a rare polarized microscope image of the edge of a crack;

[0041] Figure 18 The X-ray diffraction pattern of the pegmatite-type quartzite ore specimen in Example 2;

[0042] Figures 19-20 These are polarizing microscope images of 4N8 grade high-purity quartz sand at different magnifications in Example 2;

[0043] Figure 21 This is a single-polarized microscope image of plagioclase in Example 3;

[0044] Figure 22 These are orthogonal microscopic images of plagioclase in Example 3;

[0045] Figure 23 The X-ray diffraction pattern of the pegmatite-type quartzite ore specimen in Example 3;

[0046] Figures 24-25 These are polarized light microscope images of the rock and mineral thin sections at different positions and magnifications in Example 4. Detailed Implementation

[0047] This invention provides a method for screening potential raw materials of pegmatite-type quartz, comprising the following steps:

[0048] The first screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Quartz inclusions accounting for less than 5% of the quartz grain area and having a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers. Alternatively, quartz inclusions in which more than 70% are distributed at the edge of fractures or at different depths, and no more than 30% are distributed simultaneously at different depths, and having a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers.

[0049] The second screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Based on the quartz inclusions with a diameter of no more than 125 μm, the proportion of inclusions with a diameter of less than 1 μm in the quartz inclusions is less than 20%, which is used as a preliminary potential sample identifier.

[0050] The third screening criterion is to detect the titanium content in the pegmatite, with a titanium content ≤10ppm indicating a potential sample.

[0051] Once a sample to be screened meets the first screening criteria and / or the second screening criteria and is determined to be a preliminary potential sample, the preliminary potential sample is then judged according to the third screening criteria. Samples that meet the third screening criteria are potential raw materials for pegmatite-type quartz.

[0052] This invention does not specifically limit the source of pegmatite; any source known to those skilled in the art can be used, such as the Altay region of Xinjiang, China.

[0053] In this invention, the pegmatite geological inclusions are preferably pegmatite geological inclusion sheets, and this invention does not have any special limitation on the specific size of the pegmatite geological inclusion sheets.

[0054] In this invention, the first screening criterion is preferably: detecting the characteristics of quartz inclusions in pegmatite geological inclusions, with the quartz inclusions accounting for less than 3% of the quartz grain area and the volume ratio of gas and liquid phases in the quartz inclusions being 95% to 100% as preliminary potential sample identifiers; or with more than 70% of the quartz inclusions distributed at the edge of the fracture or at the fracture center and at different depths not exceeding 30%, and the volume ratio of gas and liquid phases in the quartz inclusions being 95% to 100% as preliminary potential sample identifiers.

[0055] In this invention, the second screening criterion is preferably: detecting the characteristics of quartz inclusions in pegmatite geological inclusions, and taking quartz inclusions with a diameter of no more than 125 μm as the basis, the proportion of inclusions with a diameter of less than 1 μm in the quartz inclusions is less than 5% as a preliminary potential sample identifier.

[0056] In this invention, the pegmatite geological inclusions are preferably distributed in different layers, and more preferably include irregular small bubbles or small particles.

[0057] In this invention, the titanium content in the pegmatite is preferably obtained by cathodic fluorescence spectroscopy. The titanium content ≤10ppm means that the spectral intensity at wavelengths of 350-500nm in the cathodic fluorescence spectrum is preferably ≤100 counts.

[0058] In this invention, the following screening criteria are preferably also included:

[0059] The fourth screening criterion is to determine the potential samples by observing the color of the quartz particles in the pegmatite. The color of the quartz particles is colorless and transparent or light smoky gray. The light smoky gray is Pantone Cool Gray 1C to 9C in the Pantone color chart.

[0060] The fifth screening criterion is to detect whether rare elements exist in the pegmatite mineralization belt, and to identify potential samples that do not contain rare metals.

[0061] The sixth screening criterion is to test the mineral composition of the pegmatite. Potential samples are identified by the bright color of the muscovite, the full lamellar structure, the garnet content not exceeding 2% by mass, and the absence of rutile.

[0062] The seventh screening criterion is to observe the mosaic characteristics of pegmatite geological thin sections, and to identify potential samples with loose bonding of quartz, feldspar, and mica, clear edges of the external shape of quartz, distinct separation of quartz, mica, and feldspar, and no mutual mosaic relationship.

[0063] The eighth screening criterion: observe the mineral composition of pegmatite geological thin sections, and identify potential samples with a reflectance of ≥60% at a wavelength of 550nm under a microscope, euhedral crystals, and a gray value of ≥200.

[0064] Ninth screening criterion: Observe the oil-immersed sections of pegmatite inclusions, and identify potential samples with an inclusion area of ​​less than 5% in the oil-immersed sections of pegmatite inclusions;

[0065] The tenth screening criterion: Detect the degree of cracking in the quartz particles within the pegmatite, and identify potential samples with a surface crack area ratio of ≤2% for the quartz particles;

[0066] Preferably, materials that meet at least 5 of the fourth to tenth screening criteria are considered as potential raw materials for pegmatite-type quartz. More preferably, materials that meet all of the first to tenth screening criteria are considered as potential raw materials for pegmatite-type quartz.

[0067] In this invention, the fourth screening criterion preferably involves selecting fresh quartz particles from pegmatite and observing the color of the quartz particles.

[0068] In this invention, the rare elements in the fifth screening criterion preferably include Li and Be. This invention does not impose any particular limitation on the detection method for these rare elements; any method well-known to those skilled in the art can be used.

[0069] In this invention, the sixth screening criterion preferably involves observing the mineral composition of the pegmatite with the naked eye or identifying the mineral composition of the pegmatite through geological thin sections.

[0070] In this invention, the pegmatite inclusion oil-impregnated slide in the ninth screening criterion is preferably prepared by a method including the following steps: crushing pegmatite to obtain crushed particles of 50-100 μm, then placing them on a glass slide, covering them with a coverslip, and dripping impregnation oil along the gap to obtain the pegmatite inclusion oil-impregnated slide.

[0071] In this invention, the impregnation oil is preferably a mixture of tribromomethane and ethanol, and the volume ratio of tribromomethane to ethanol in the mixture is preferably 97:3. Limiting the volume ratio of tribromomethane to ethanol to 97:3 enables the refractive index of the impregnation oil to be close to that of quartz.

[0072] The present invention does not have a special limitation on the mass ratio of the crushed particles to the mixture, as long as the mixture covers the crushed particles.

[0073] The present invention preferably uses artificial intelligence or statistical algorithm software to assist in calculating the area to obtain the area ratio of the pegmatite inclusions in the oil-impregnated slice.

[0074] This invention uses the first and second screening criteria as the main reference criteria, the third screening criteria as the key focus criteria, and samples that meet five or more of the fourth to tenth screening criteria can be used as potential samples for further mineral processing and purification tests. More preferably, samples that meet the first to tenth screening criteria can be used as potential raw materials for pegmatite-type quartz.

[0075] The screening method of this invention requires a small amount of pegmatite raw material (as low as 5 kg), allowing geological workers to collect a large number of different mineral samples in remote fields (traditional mineral processing requires at least 100 kg of samples). The screening method is fast and simple, and potential samples can be quickly identified by examining inclusions. Non-potential samples can be directly rejected, thus quickly finding high-quality mineral sources and avoiding wasted effort (mineral processing and purification of each sample is time-consuming, labor-intensive, and expensive; compared to traditional direct mineral processing methods, screening and identifying raw materials before mineral processing is the advantage of this invention). Mineral processing and purification using the screening method of this invention can be completed in 3-5 days, compared to 1-2 months for traditional mineral processing, which is a significant time advantage. Furthermore, the screening method of this invention can be used for batch experiments in the laboratory, while traditional mineral processing processes can only be carried out one by one, greatly improving work progress.

[0076] This invention also provides a method for preparing 4N8 grade high-purity quartz sand, comprising the following steps:

[0077] Using the screening method described in the above technical solution, potential raw materials of pegmatite-type quartz are obtained;

[0078] The pegmatite-type quartz potential raw material is subjected to crushing, acid washing, weak magnetic separation, strong magnetic separation, flotation, roasting and water quenching, acid leaching, drying and chlorination purification in sequence to obtain the 4N8 grade high-purity quartz sand. The magnetic field strength of the weak magnetic separation is 0.1~0.5T and the magnetic field strength of the strong magnetic separation is 1.5~1.7T.

[0079] The present invention utilizes the screening method described in the above technical solution to obtain potential raw materials of pegmatite-type quartz.

[0080] After obtaining the pegmatite-type quartz potential raw material, the present invention sequentially performs crushing, acid washing, weak magnetic separation, strong magnetic separation, flotation, roasting and water quenching, acid leaching, drying and chlorination purification on the pegmatite-type quartz potential raw material to obtain the 4N8 grade high-purity quartz sand. The magnetic field strength of the weak magnetic separation is 0.1~0.5T, and the magnetic field strength of the strong magnetic separation is 1.5~1.7T.

[0081] In this invention, the particle size after crushing is preferably 1-3 cm, more preferably 2-3 cm.

[0082] After the crushing is completed, the present invention preferably performs manual sorting or color sorting to screen quartz minerals before performing acid washing.

[0083] In this invention, the pickling agent preferably includes dilute hydrochloric acid, and the mass percentage of the dilute hydrochloric acid is preferably 5% to 10%. This invention does not have a special limitation on the amount of dilute hydrochloric acid used. The pickling is sufficient until the surface of the quartz mineral is clean and transparent without any clay or other colored minerals.

[0084] After the pickling is completed, the present invention preferably dries and finely crushes the resulting pickled product in sequence. The present invention does not have specific limitations on the specific parameters of the drying process; methods well known to those skilled in the art can be used.

[0085] In this invention, the fine crushing is preferably processed to 120 mesh.

[0086] In this invention, the crushing and fine crushing process should not introduce new impurities. It is preferred to use processing equipment made of zirconium oxide or silicon carbide ceramic materials, or to install or coat the surface of the processing equipment with polytetrafluoroethylene material. The processing workshop is a pollution-free workshop, and the finished products are immediately packed into sealed bags.

[0087] In this invention, the amount of the acid-washed sample is preferably not less than 1 kg.

[0088] In this invention, the total time for crushing and pickling is preferably no more than 2 hours.

[0089] In this invention, the weak magnetic separation and strong magnetic separation are used to remove magnetic minerals.

[0090] In this invention, the magnetic field strength of the weak magnetic separation can be 0.1, 0.2, 0.3, 0.4 or 0.5T, and the magnetic field strength of the strong magnetic separation can be 1.5, 1.6 or 1.7T.

[0091] In this invention, the weak magnetic separation is preferably performed once, and the strong magnetic separation is preferably performed twice.

[0092] The present invention preferably uses a drum-type weak magnetic separator for weak magnetic separation first, and then uses a high-gradient strong magnetic separator for strong magnetic separation.

[0093] In this invention, after the strong magnetic separation is completed, the product is preferably sealed and stored, and the amount of sample obtained after magnetic separation is preferably not less than 300g.

[0094] In this invention, the total time for weak magnetic separation and strong magnetic separation is preferably no more than 1 hour.

[0095] In this invention, the collector used in the flotation preferably includes dodecylamine and octadecylamine, and the mass ratio of dodecylamine to octadecylamine in the collector is preferably 1:1.5 to 2, specifically 1:1.5 or 1:2.

[0096] In this invention, the flotation preferably uses kerosene solution as an auxiliary collector and frother, and the mass percentage of the kerosene solution is preferably 98%.

[0097] After the strong magnetic separation is completed, the present invention preferably mixes the obtained product with flotation water to obtain a slurry, and then mixes the slurry, pH adjuster, collector and kerosene solution to carry out the flotation.

[0098] In this invention, the water used for flotation is preferably laboratory grade II pure water or ultrapure water, and the resistivity of the ultrapure water is preferably 18.2 MΩ.

[0099] In this invention, the temperature of the water used for flotation is preferably 50-60°C, specifically 50, 55 or 60°C.

[0100] In this invention, the mass percentage of the slurry is preferably 20% to 30%, specifically 20%, 25%, or 30%.

[0101] In this invention, the pH adjuster is preferably hydrofluoric acid. This invention does not have any special limitations on the amount and concentration of hydrofluoric acid, as long as the pH of the flotation system is preferably 2 to 3.

[0102] In this invention, the volume ratio of the slurry to the kerosene solution is preferably 500:1 to 3, specifically 500:1, 500:1.5, 500:2 or 500:3.

[0103] In this invention, based on 500 mL of the slurry, the amount of the mixed amine is preferably 3 to 6 drops, specifically 3, 4, 5 or 6 drops.

[0104] In this invention, the flotation time is preferably 10 to 15 minutes, specifically 10 or 15 minutes.

[0105] In this invention, after the flotation is completed, it is preferable to further add water to remove foam, and then put it into a high-purity quartz glass container to dry.

[0106] In this invention, the high-purity quartz glassware is preferably heat-resistant to 1600°C or higher.

[0107] The present invention does not impose any special limitations on the specific parameters of the drying process, as long as the moisture can be completely removed.

[0108] In this invention, the number of flotation cycles is preferably 1 to 3 times, specifically 1, 2 or 3 times.

[0109] In this invention, the sample obtained after flotation preferably does not contain mica, and the mass of the sample is preferably not less than 40g.

[0110] In this invention, the flotation time is preferably no more than 2 hours.

[0111] In this invention, the roasting temperature during roasting and water quenching is preferably 1000–1500℃, specifically 1000, 1100, 1200, 1300, 1400, or 1500℃, and the time is preferably 0.5–1 h, specifically 0.5 or 1 h. The water quenching temperature during roasting and water quenching is preferably 50–80℃, specifically 50, 60, 70, or 80℃, and the time is preferably 0.5–1 min, specifically 0.5 or 1 min. The roasting and water quenching can remove organic impurities and volatile substances, change the morphology and activity of impurity minerals, and promote the rupture of fluid inclusions. The water quenching function is to induce microcracks, strengthen physical fracturing, optimize the quartz crystal structure, and allow the mixed acid to better penetrate and remove impurity elements during subsequent acid leaching. The water quenching process is an instantaneous reaction.

[0112] In this invention, the water used for calcination water quenching is preferably ultrapure water, and the resistivity of the ultrapure water is preferably 18.2 MΩ.

[0113] In this invention, the sample obtained after flotation is preferably transferred into a heating device for roasting, and the roasted sample is then transferred into water for water quenching.

[0114] In this invention, after calcination and water quenching, the resulting sample is preferably transferred to a quartz container for drying, and then stored in a sealed bag. This invention does not have specific limitations on the drying parameters, as long as the moisture can be completely removed.

[0115] In this invention, the calcination and water quenching time is preferably no more than 2 hours.

[0116] In this invention, the mixed acid used for acid leaching preferably includes concentrated hydrochloric acid, hydrofluoric acid and concentrated nitric acid. The mass concentration of the concentrated hydrochloric acid is preferably 36% to 38%, the mass concentration of the concentrated nitric acid is preferably 40% to 68%, the mass concentration of the hydrofluoric acid is preferably 35% to 45%, and the volume ratio of the concentrated hydrochloric acid, hydrofluoric acid and concentrated nitric acid in the mixed acid is preferably 20:6:2.

[0117] In this invention, the preferred ratio of the sample obtained after calcination and water quenching to the mixed acid is 20-30g:28mL, specifically 20g:28mL, 25g:28mL or 30g:28mL.

[0118] In this invention, the acid leaching process aims to deeply remove impurities through chemical means. Through selective dissolution, ion exchange, and complexation reactions, it precisely removes trace impurities from the interior and surface of the quartz crystal. Specifically, it dissolves metal oxides and amorphous impurities, removing metal oxides (including iron oxide, aluminum oxide, titanium dioxide, calcium oxide, and magnesium oxide) as well as residual amorphous silicates after calcination. It also removes ionic impurities released from fluid inclusions (including Na+ released from ruptured inclusions after calcination and water quenching). + K + Cl - Soluble ions), an acidic environment (preferably pH < 2) can inhibit the re-adsorption of these ionic impurities, leach them out of the quartz microcracks through diffusion, and at the same time destroy the crystal structure of impurity minerals (including incompletely decomposed feldspar and mica residues).

[0119] In this invention, the acid leaching process preferably includes the addition of complexing agents, reducing agents, and surfactants, which can further improve the purity of 4N8 grade high-purity quartz sand.

[0120] In this invention, the complexing agent preferably includes ethylenediaminetetraacetic acid (EDTA), the function of which is to complex Fe. 3+ And Al 3+ To prevent precipitation, in acidic environments (such as HCl or sulfuric acid commonly used in acid leaching), Fe... 3+ And Al 3+ Hydrolysis may still occur due to local pH increases or temperature fluctuations, producing Fe(OH)3 and Al(OH)3. EDTA can react with Fe... 3+ And Al 3 + Forming stable water-soluble complexes (such as Fe(EDTA)Fe(EDTA)) -And Al(EDTA)Al(EDTA) - This significantly reduces the concentration of free metal ions, preventing them from reaching the solubility product required for hydroxide precipitation, thereby inhibiting precipitate formation. Furthermore, if sulfuric acid is used for acid leaching, Fe... 3+ Possibly related to SO4 2- The formation of insoluble ferric sulfate (such as ferrous sulfate compounds) by EDTA complexation can reduce Fe. 3+ The effective concentration of EDTA indirectly inhibits the precipitation of such salts. If the acid leaching system contains anions such as phosphate, EDTA can also prevent the formation of corresponding sparingly soluble salts by complexing metal ions.

[0121] In this invention, the mass of the complexing agent is preferably 0.1% to 0.5% of the mass of the sample obtained after calcination and water quenching, specifically 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0122] In this invention, the reducing agent preferably includes oxalic acid, and the function of the reducing agent is to reduce Fe... 3+ Reduced to Fe 2+ This increases the dissolution rate.

[0123] In this invention, the mass of the reducing agent is preferably 0.1% to 0.5% of the mass of the sample obtained after calcination and water quenching, specifically 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0124] In this invention, the surfactant preferably includes sodium dodecyl sulfate, and the surfactant functions to reduce surface tension and promote the penetration of mixed acid into microcracks during acid leaching.

[0125] In this invention, the mass of the surfactant is preferably 0.05% to 0.1% of the mass of the sample obtained after calcination and water quenching, specifically 0.05% or 0.1%.

[0126] In this invention, the acid leaching is preferably performed by placing the sample obtained after calcination and water quenching in a polytetrafluoroethylene beaker, then adding the mixed acid, placing it in a water oscillator, sealing and leaching for 12 hours. The water bath temperature of the water oscillator is preferably 60°C, and the water oscillator is repeatedly oscillated, preferably stirred once every 2 hours.

[0127] In this invention, the time required for the sample obtained after roasting and water quenching to complete acid leaching is preferably no more than 13 hours.

[0128] In this invention, after the acid leaching is completed, the obtained acid leaching product is preferably washed with ultrapure water. The number of times the ultrapure water is washed is preferably 6 to 8 times, specifically 6, 7 or 8 times.

[0129] In this invention, the drying temperature is preferably 80-100°C, specifically 80, 90 or 100°C, and the drying time is preferably no more than 4 hours.

[0130] In this invention, the drying is preferably carried out in a quartz vessel.

[0131] In this invention, the drying process preferably includes natural cooling to room temperature after completion.

[0132] In this invention, the preferred temperature for chlorination purification is 1000-1400℃, specifically 1000, 1100, 1200, 1300 or 1400℃, and the preferred time is 0.5-1h. The chlorination purification is preferably carried out in chlorine gas or hydrogen chloride gas.

[0133] In this invention, the dried sample is preferably poured into a chlorination furnace, and chlorine gas is introduced into the pipeline of the chlorination furnace to carry out the chlorination purification.

[0134] In this invention, the chlorination gas is preferably chlorine or hydrogen chloride gas.

[0135] In this invention, based on 50g of the dried sample, the introduction of chlorine gas preferably includes the following steps: the flow rate of the chlorine gas is 0.2-0.3 L / min for the first 10 minutes, and then the chlorine gas is introduced at a flow rate of 0.1 L / min for 20 minutes.

[0136] After the chlorination purification is completed, the present invention preferably treats the tail gas, collects the sample, washes it with water 3 to 5 times, dries it to obtain the 4N8 grade high-purity quartz sand, and puts the 4N8 grade high-purity quartz sand into a sealed bag for purification sample testing.

[0137] In this invention, the tail gas is preferably absorbed by sodium hydroxide, and then the resulting product is evaporated and crystallized to obtain sodium chloride crystals.

[0138] In this invention, the time from the start of chlorination purification to obtaining the 4N8 grade high-purity quartz sand is preferably no more than 4 hours.

[0139] In this invention, the purification sample test is preferably the detection of impurity elements in the obtained 4N8 grade high-purity quartz sand, and the specific reference standards are GB / T 3284-2015 and GB / T 32649-2016.

[0140] In this invention, the time required for testing the purified sample is preferably no more than 8 hours.

[0141] In this invention, the preparation time of the 4N8 grade high-purity quartz sand is preferably no more than 28 hours, the screening time is preferably no more than 8 hours, the purification sample testing time is preferably no more than 8 hours, and the total time is no more than 44 hours. Based on an 8-hour workday, the entire process only takes 5.5 days. If the acid leaching is carried out at night, since no human operation is required, the entire process can be completed in only 4 days.

[0142] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0143] Example 1

[0144] (1) Characteristics of pegmatite-type quartzite ore specimens

[0145] Specimen number: SY-07-27-08

[0146] Field identification description of the specimen: This specimen is a granite pegmatite. The rock is generally yellowish-grayish-white, with a granite pegmatitic texture and massive structure. The rock minerals consist of quartz, plagioclase, and muscovite. Quartz is colorless and transparent, anhedral granular, with a greasy luster, a grain size of 0.2–4 mm, and a content of 30 wt%. Plagioclase is white, anhedral columnar granular, with a grain size of 0.2–6 mm, and a content of 66 wt%. Muscovite is mostly distributed in small scaly or subhedral platy masses, with a flake size of 0.1–4 mm, and a content of 4 wt%. The rock shows limonite dissipation in a massive distribution. The rock surface is soild.

[0147] Specimen photos Figure 2 As shown.

[0148] (2) Identification of purified quartz sand, thin sections of rock minerals, and inclusions

[0149] The rock within the thin section is an acidic shallow to ultrashallow intrusive rock mainly composed of quartz, plagioclase, potassium feldspar, and muscovite. It exhibits a granitic pegmatitic texture and no directional structure. Quartz is anhedral granular, with a grain size of 0.02–1.24 mm, locally showing recrystallization along fractures, and contains 15 wt%. Plagioclase is subhedral prismatic, with a grain size of 0.03–5.6 mm; polysynthetic twinning of feldspar is visible under crossed microscopes, and some surfaces are earthy. Feldspar is mostly stress-fragmented into small particles, and contains 60 wt%. Potassium feldspar is subhedral prismatic, with lattice twinning, with a grain size of 0.02–5.6 mm, and contains 5 wt%. Muscovite is euhedral platy, with a grain size of 0.08–1.62 mm, exhibiting one set of perfect cleavage, bright interference colors under crossed microscopes, and nearly parallel extinction, and contains 10 wt%. The edges of the muscovite are earthy. The rock is argillaceous, with newly formed argillaceous minerals frequently found along the fissures between rock grains. Plagioclase is mostly argillaceous, appearing black, and adhering to the surface of the feldspar, accounting for 10 wt%. Apatite is present, in acicular and columnar forms, in small quantities. Thin sections show limonite mineralization and argillaceous formations forming ferruginous argillaceous material.

[0150] Figures 3-7 These are polarized microscope images of thin sections of rocks and minerals at different positions and magnifications.

[0151] Microscopic identification of inclusions:

[0152] The sample contains a high amount of quartz inclusions, mostly fluid inclusions, followed by solid inclusions, which together account for 12 wt% of the quartz.

[0153] Fluid inclusions: Mostly liquid-rich inclusions, with a gas-liquid ratio of 1:3 to 1:8. They are mostly spherical or elliptical in shape, pure liquid inclusions, and range in size from 0.9 to 3.3 μm. Fluid inclusions are arranged linearly in a beaded or ribbon-like pattern, often distributed along fractures or in stacked formations, and are mostly larger than 1 μm. Fluid inclusions account for 3.5 wt% of the quartz content.

[0154] Solid inclusions: Most solid inclusions are elliptical or short columnar, ranging in size from 2.6 to 11.5 μm, and are scattered. Solid inclusions account for less than 0.5 wt% of the quartz content. Needle-like columnar apatite inclusions are also observed.

[0155] Inclusion particle size analysis:

[0156] Inclusions, greater than 1 μm, 90 wt%; less than 1 μm, 10 wt%.

[0157] (3) Phase analysis

[0158] Phase analysis of pegmatite-type quartzite ore samples yielded the following results: potassium feldspar content was 2.77 wt%, plagioclase content was 63.93 wt%, dolomite content was 6.68 wt%, and quartz content was 26.61 wt%.

[0159] X-ray diffraction pattern of pegmatite-type quartzite ore specimen as shown in the figure. Figure 8 As shown.

[0160] (4) Conclusion

[0161] 1. The identification name of this thin section is muscovite granite pegmatite.

[0162] 2. The inclusions within the thin quartz slices are unevenly distributed, with some areas having more inclusions. The quartz grains observed under the thin slices appear quite translucent, suggesting a high purity after purification. Purification tests can be conducted to corroborate this finding.

[0163] 3. After the quartz sample was crushed, its inclusion distribution was observed. The overall content of clay was high, the fissures were well developed, and most of the samples were opaque. Fluid inclusions were visible inside some of the quartz.

[0164] Figure 1 This is a flowchart illustrating the preparation and testing method of the 4N8 grade high-purity quartz sand in this embodiment. The pegmatite-type quartz potential raw material obtained by the screening method is sequentially subjected to preliminary crushing, acid washing, fine crushing, weak magnetic separation, strong magnetic separation, flotation, roasting and water quenching, acid leaching, drying, and chlorination purification to obtain the 4N8 grade high-purity quartz sand. Then, testing is performed. The specific steps are as follows:

[0165] The pegmatite-type quartz raw material is initially crushed to 1-2 cm. Take 5 kg of the initially crushed sample and first hand-sort the quartz minerals. Then, acid wash it with 10% hydrochloric acid by mass until the surface of the quartz minerals is clean and transparent without mud or other colored minerals. Then dry it. After drying, the sample is finely crushed to 120 mesh. No new impurities are introduced during the initial crushing and fine crushing process. Zirconia material processing equipment is used. After processing, the sample is immediately put into a sealed bag. The sample amount is not less than 1 kg. This step takes 2 hours.

[0166] After obtaining the finely crushed sample, it can be first subjected to weak magnetic separation once with a drum-type weak magnetic separator at a magnetic separation intensity of 0.2T, and then subjected to strong magnetic separation twice with a high gradient strong magnetic separator at a magnetic separation intensity of 1.5T. After the magnetic separation is completed, it should be sealed and stored. The amount of magnetically separated sample should not be less than 300g. This step takes 1 hour.

[0167] After magnetic separation, the samples underwent two flotation processes. The flotation water was ultrapure water with a resistivity of 18.2 MΩ, at a temperature of 55℃, with a pulp concentration of 20%. The pH was adjusted to 2 using 15% pure hydrofluoric acid (by mass). The collector was a mixture of dodecylamine and octadecylamine in a 1:2 mass ratio. Five drops of the mixed amine solution were added to 500 mL of pulp. Kerosene was used as an auxiliary collector and frother; 2 mL of 98 wt% kerosene was added to 500 mL of pulp. The flotation process lasted 10 minutes. After adding water to remove foam, the first flotation is completed. Then, the second flotation is carried out at a water temperature of 55℃ and a pulp concentration of 20%. The pH adjuster and mixed amine are the same as in the first flotation. Add 3 drops of mixed amine to 500mL of pulp and 1.0mL of 98wt% kerosene to 500mL of pulp. After flotation for 10 minutes, add water to remove foam. After the two flotations are completed, rinse with water 3 times and put into a high-purity quartz glass container (the container can withstand temperatures above 1600℃) and dry at 90℃. The sample amount is not less than 40g. This step takes 2 hours.

[0168] In the roasting and water quenching process, after drying, the sample was transferred to a heating device at 1100℃ for roasting for 30 minutes. After roasting, the sample was transferred to 60℃ warm water (using ultrapure water with a resistivity of 18.2MΩ) for water quenching. After water quenching, the sample was transferred to a quartz container for drying and then stored in a sealed bag. This step took 2 hours.

[0169] In the acid leaching step, 20g of the roasted and water-quenched sample was weighed into a polytetrafluoroethylene beaker, and a mixed acid solution (20mL of 36% concentrated hydrochloric acid, 6mL of 40% hydrofluoric acid, and 2mL of 60% concentrated nitric acid) was added. The sample was then placed in a water bath shaker, sealed, and acid-leached for 12 hours at a water bath temperature of 60℃. The water bath process was repeatedly shaken and stirred every 2 hours. This step took 13 hours.

[0170] In the drying process, after acid leaching, the container is rinsed 6 times with ultrapure water, placed in a quartz container, dried at 90°C, and then allowed to cool naturally. This process takes 4 hours.

[0171] In the chlorination purification process, 50g of the dried sample was placed in a chlorination furnace, and chlorine gas was introduced into the pipeline. The furnace temperature was 1400℃, and chlorine gas was continuously introduced for 30min (the flow rate of chlorine gas was 0.3L / min for the first 10min, and then 0.1L / min for 20min). The tail gas was treated (the tail gas was absorbed by sodium hydroxide, and then the obtained product was evaporated and crystallized to obtain sodium chloride crystals). The sample was collected, washed with water 5 times, and dried to obtain 48.0g of 4N8 grade high-purity quartz sand. The sand was placed in a sealed bag for purification sample testing. This step took 4 hours.

[0172] Figures 9-11These are polarized light microscope images of 4N8 grade high-purity quartz sand at different magnifications.

[0173] Figure 12 This is a picture of a 4N8 grade high-purity quartz sand.

[0174] The mass content of silica in the 4N8 grade high-purity quartz sand was determined using GB / T 3284-2015, and the result was 99.9975%.

[0175] The metal content in the 4N8 grade high-purity quartz sand was determined using GB / T 32649-2016. The metal content was found to be: cobalt 0.00 μg / g, nickel 0.35 μg / g, iron 0.01 μg / g, manganese 0.02 μg / g, chromium 0.00 μg / g, magnesium 0.00 μg / g, calcium 0.56 μg / g, copper 0.68 μg / g, titanium 4.38 μg / g, zirconium 0.43 μg / g, aluminum 9.89 μg / g, barium 0.02 μg / g, sodium 2.04 μg / g, lithium 0.09 μg / g, and potassium 6.09 μg / g.

[0176] Example 2

[0177] (1) Characteristics of pegmatite-type quartzite ore specimens

[0178] Specimen number: SY-07-27-09

[0179] Field identification description of the specimen: This specimen is a muscovite granite pegmatite. The rock is grayish-white overall, with a granite pegmatitic texture and massive structure. The rock minerals are mainly composed of quartz, plagioclase, and muscovite. Quartz is colorless and transparent, subhedral to anhedral granular, with a greasy luster, a grain size of 0.2–5 mm, and a content of 45 wt%. Plagioclase is white, subhedral to anhedral columnar granular, with a grain size of 0.2–12 mm, and locally feldspar is found in clusters, with a content of 50 wt%. Muscovite is subhedral to euhedral platy, with a platy diameter of 0.2–6 mm, and the muscovite is unevenly distributed, mostly in small clusters, with a content of 5 wt%. A small amount of sericite is found, with local limonite mineralization.

[0180] (2) Identification of purified quartz sand, thin sections of rock minerals, and inclusions

[0181] The rock in the thin section is primarily an acidic shallow to ultrashallow intrusive rock composed of quartz and plagioclase. It exhibits a granitic pegmatitic texture and lacks directional structure. Quartz is anhedral granular, with a grain size of 0.02–2.4 mm. The quartz exhibits stress-induced fracturing, showing a conchoidal fracture with good optical properties, and contains 82 wt% (the thin section selected reflects a higher quartz content compared to other rock sections). Plagioclase is subhedral prismatic, with a grain size of 0.4–12 mm, some surfaces showing earthiness, and contains 10 wt%. The rock is argillaceous, with newly formed argillaceous minerals frequently observed along the intergranular fissures. The plagioclase is argillaceous, with the argillaceous material appearing as black streaks on the feldspar surface, and contains 8 wt%.

[0182] Microscopic fractures are well-developed in quartz, accounting for 15% of the quartz.

[0183] Figures 13-17 These are polarized light microscope images of thin sections of rocks and minerals at different positions and magnifications. Figure 15 These are common polarized microscope images of the edges of cracks. Figure 16 These are rare polarized microscope images of the edge of a crack.

[0184] Microscopic identification of inclusions:

[0185] The quartz in this sample is relatively pure internally, but it exhibits well-developed fissures filled with clay. The clay is mostly scattered within the micro-fissures of the quartz, and fluid inclusions are observed around the clay filling. Overall, this accounts for 3% of the quartz.

[0186] Fluid inclusions: Mostly liquid-rich inclusions, with a gas-liquid ratio of 1:2 to 1:8. They are mostly round, elliptical, or irregular in shape; pure liquid inclusions are rare. Fluid inclusions range from 0.6 to 3.6 μm in size. They are randomly stacked and distributed at the edges of localized argillaceous fractures and within quartz fractures, exhibiting a beaded arrangement. Most fluid inclusions are larger than 1 μm. Fluid inclusions account for approximately 3 wt% of the quartz content.

[0187] Solid inclusions: Seen as round solid inclusions, 0.7–2.1 μm in size, in small quantities.

[0188] Inclusion particle size analysis:

[0189] Inclusions, greater than 1 μm, 90 wt%; less than 1 μm, 10 wt%.

[0190] (3) Phase analysis

[0191] Phase analysis of pegmatite-type quartzite ore samples yielded the following results: potassium feldspar content was 21.69 wt%, plagioclase content was 63.93 wt%, and quartz content was 78.31 wt%.

[0192] X-ray diffraction pattern of pegmatite-type quartzite ore specimen as shown in the figure. Figure 18 As shown.

[0193] (4) Conclusion

[0194] 1. The identification name of this thin section is granite pegmatite.

[0195] 2. The quartz flakes are relatively clean, and the quartz grains have high permeability. Fluid inclusions are present, but the inclusions are mostly distributed along the clay-filled material in the fractures and the content is not high.

[0196] 3. After the quartz sample was crushed, the distribution of its inclusions was observed. It can be seen that the interior of the quartz is relatively clean and pure, and inclusions are visible in some quartz fractures. Further research on high-purity quartz can be carried out.

[0197] The specific steps for preparing 4N8 grade high-purity quartz sand are as follows:

[0198] The pegmatite-type quartz raw material is initially crushed to 1-2 cm. Take 5 kg of the initially crushed sample and first hand-sort the quartz minerals. Then, acid wash it with 5% hydrochloric acid by mass until the surface of the quartz minerals is clean and transparent without mud or other colored minerals. Then dry it. After drying, the sample is finely crushed to 120 mesh. No new impurities are introduced during the initial crushing and fine crushing process. Zirconia material processing equipment is used. After processing, the sample is immediately put into a sealed bag. The sample amount is not less than 1 kg. This step takes 2 hours.

[0199] After obtaining the finely crushed sample, it can be first subjected to weak magnetic separation once with a drum-type weak magnetic separator at a magnetic separation intensity of 0.5T, and then subjected to strong magnetic separation twice with a high gradient strong magnetic separator at a magnetic separation intensity of 1.7T. After the magnetic separation is completed, it should be sealed and stored. The amount of magnetically separated sample should be no less than 300g. This step takes 1 hour.

[0200] After magnetic separation, the samples underwent two flotation processes. The flotation water was ultrapure water with a resistivity of 18.2 MΩ, at a temperature of 55℃, with a pulp concentration of 30%. The pH was adjusted to 2 using 15% pure hydrofluoric acid (by mass). The collector was a mixture of dodecylamine and octadecylamine in a 1:2 mass ratio. Five drops of the mixed amine solution were added to 500 mL of pulp. Kerosene was used as an auxiliary collector and frother; 2 mL of 98 wt% kerosene was added to 500 mL of pulp. The flotation process lasted 10 minutes. After adding water to remove foam, the first flotation is completed. Then, the second flotation is carried out at a water temperature of 55℃ and a pulp concentration of 30%. The pH adjuster and mixed amine are the same as in the first flotation. Add 3 drops of mixed amine to 500mL of pulp and 1.0mL of 98wt% kerosene to 500mL of pulp. After flotation for 10 minutes, add water to remove foam. After the two flotations are completed, rinse with water 3 times and put into a high-purity quartz glass container (the container can withstand temperatures above 1600℃) and dry at 90℃. The sample amount is not less than 40g. This step takes 2 hours.

[0201] In the roasting and water quenching process, after drying, the sample was transferred to a heating device at 1400℃ for roasting for 30 minutes. After roasting, the sample was transferred to 60℃ warm water (using ultrapure water with a resistivity of 18.2MΩ) for water quenching. After water quenching, the sample was transferred to a quartz container for drying and then stored in a sealed bag. This step took 2 hours.

[0202] In the acid leaching step, 20g of the roasted and water-quenched sample was weighed into a polytetrafluoroethylene beaker, and a mixed acid solution (20mL of 36% concentrated hydrochloric acid, 6mL of 40% hydrofluoric acid, and 2mL of 60% concentrated nitric acid) was added. The sample was then placed in a water bath shaker, sealed, and acid-leached for 12 hours at a water bath temperature of 60℃. The water bath process was repeatedly shaken and stirred every 2 hours. This step took 13 hours.

[0203] In the drying process, after acid leaching, the container is rinsed 6 times with ultrapure water, placed in a quartz container, dried at 90°C, and then allowed to cool naturally. This process takes 4 hours.

[0204] In the chlorination purification process, 50g of the dried sample was placed in a chlorination furnace, and chlorine gas was introduced into the pipeline. The furnace temperature was 1400℃, and chlorine gas was continuously introduced for 30min (the chlorine gas flow rate was 0.3L / min for the first 10min, and then 0.1L / min for 20min). The tail gas was treated (the tail gas was absorbed by sodium hydroxide, and then the obtained product was evaporated and crystallized to obtain sodium chloride crystals). The sample was collected, washed with water 5 times, and dried to obtain 48.6g of 4N8 grade high-purity quartz sand. The sand was placed in a sealed bag for purification sample testing. This step took 4 hours.

[0205] Figures 19-20 These are polarized light microscope images of 4N8 grade high-purity quartz sand at different magnifications.

[0206] The mass content of silica in the 4N8 grade high-purity quartz sand was determined using GB / T 3284-2015, and the result was 99.9980%.

[0207] The metal content in the 4N8 grade high-purity quartz sand was determined using GB / T 32649-2016. The metal content was found to be: cobalt 0.00 μg / g, nickel 0.09 μg / g, iron 0.01 μg / g, manganese 0.06 μg / g, chromium 0.00 μg / g, magnesium 0.00 μg / g, calcium 0.27 μg / g, copper 0.69 μg / g, titanium 3.88 μg / g, zirconium 0.19 μg / g, aluminum 11.00 μg / g, barium 0.03 μg / g, sodium 1.59 μg / g, lithium 0.66 μg / g, and potassium 1.20 μg / g.

[0208] Example 3

[0209] (1) Characteristics of pegmatite-type quartzite ore specimens

[0210] Specimen number: SY-07-27-10

[0211] Field identification description of the specimen: This specimen is a muscovite granite pegmatite. The rock is grayish-white overall, with a granite pegmatitic texture and massive structure. The rock minerals are mainly composed of quartz, plagioclase, and muscovite. Quartz is colorless and transparent, anhedral granular, with a greasy luster, a grain size of 0.2–4 mm, and a content of 25 wt%. Plagioclase is white, subhedral to anhedral columnar granular, with a grain size of 0.2–8 mm, and a content of 65 wt%. Muscovite is subhedral to euhedral platy, with a platy diameter of 0.2–7 mm; muscovite is often found in aggregates, and a content of 10 wt%.

[0212] Goethite mineralization is observed on the rock fissure surfaces. Feldspar exhibits earthiness, is sticky to the touch, and appears white.

[0213] (2) Identification of purified quartz sand, thin sections of rock minerals, and inclusions

[0214] The rock within the thin section is primarily composed of quartz and plagioclase, representing an acidic shallow to ultrashallow intrusive rock. It exhibits a granitic pegmatitic texture and lacks directional structure. Quartz, anhedral granular, ranges in size from 0.01 to 1.55 mm; the quartz grains are stressed, exhibiting wavy extinction and conchoidal fracture optical properties, with a content of 308 wt%. Plagioclase, subhedral prismatic, ranges in size from 0.01 to 4.8 mm, and is visible under a single-polarized microscope. Figure 21 Under orthogonal lenses (see) Figure 22 Feldspar polysynthetic twinning is visible, with some surfaces exhibiting earthiness, comprising 51 wt%. Muscovite, euhedral platy, 0.07–3.6 mm in diameter, possesses one set of perfectly perfect cleavages; under crossed microscopes, interference colors are bright, with near-parallel extinction, comprising 15 wt%. The surface of the muscovite exhibits muddiness, developed along the cleavages. The rock is argillaceous, with newly formed argillaceous minerals frequently observed along intergranular fissures. Plagioclase is mostly muddled, appearing black, and adheres to the feldspar surface, comprising 4 wt%.

[0215] The limonite is observed to be mineralized, and the muddy material at the edges is stained to resemble iron mud.

[0216] Microscopic identification of inclusions:

[0217] The quartz in this film is relatively pure. Fluid inclusions are seen in the cracks between the quartz particles, and solid inclusions are seen at the contact points between the particles. The total amount of inclusions is 1 wt% of the quartz.

[0218] Fluid inclusions: Mostly liquid-rich inclusions, with a gas-liquid ratio of 1:2 to 1:8. They are mostly round or elliptical, with some irregular shapes. Pure liquid inclusions are occasionally seen. Fluid inclusions range from 0.7 to 7.9 μm. On some quartz specimens, fluid inclusions are observed arranged linearly in a beaded pattern along quartz fractures. These fluid inclusions are mostly larger than 1 μm. Fluid inclusions account for 3 wt% of the quartz content.

[0219] Solid inclusions: Occasionally, solid inclusions are found in the quartz grain fissures and clay-filled areas. They are elliptical or nearly round, with a size of 0.7–13.4 μm, and are distributed in a beaded stacking pattern.

[0220] Inclusion particle size analysis:

[0221] Inclusions, greater than 1 μm, 80 wt%; less than 1 μm, 20 wt%.

[0222] (3) Phase analysis

[0223] Phase analysis of pegmatite-type quartzite ore samples yielded the following results: potassium feldspar content was 39.42 wt%, muscovite content was 5.01 wt%, and quartz content was 55.57 wt%.

[0224] X-ray diffraction pattern of pegmatite-type quartzite ore specimen as shown in the figure. Figure 23 As shown.

[0225] (4) Conclusion

[0226] 1. The identification name of this thin section is muscovite granite pegmatite.

[0227] 2. The quartz flakes are relatively clean, with high quartz transparency. Fluid and solid inclusions are present, but the inclusion content is low, allowing for further research into high-purity quartz.

[0228] 3. After the quartz sample was crushed, its inclusion distribution was observed. It can be seen that the interior of the quartz is relatively clean and pure, but the overall purified sand has developed fissures with clay-like inclusions. The purified sand particles are dark in color and have poor transparency.

[0229] The specific steps for preparing 4N8 grade high-purity quartz sand are as follows:

[0230] The pegmatite-type quartz raw material is initially crushed to 1-2 cm. Take 5 kg of the initially crushed sample and first hand-sort the quartz minerals. Then, acid wash it with 10% hydrochloric acid by mass until the surface of the quartz minerals is clean and transparent without mud or other colored minerals. Then dry it. After drying, the sample is finely crushed to 120 mesh. No new impurities are introduced during the initial crushing and fine crushing process. Zirconia material processing equipment is used. After processing, the sample is immediately put into a sealed bag. The sample amount is not less than 1 kg. This step takes 2 hours.

[0231] After obtaining the finely crushed sample, it can be first subjected to weak magnetic separation once with a drum-type weak magnetic separator at a magnetic separation intensity of 0.4T, and then subjected to strong magnetic separation twice with a high gradient strong magnetic separator at a magnetic separation intensity of 1.6T. After the magnetic separation is completed, it should be sealed and stored. The amount of magnetically separated sample should be no less than 300g. This step takes 1 hour.

[0232] After magnetic separation, the samples underwent two flotation processes. The flotation water was ultrapure water with a resistivity of 18.2 MΩ, at a temperature of 55℃, with a pulp concentration of 30%. The pH was adjusted to 2 using 15% pure hydrofluoric acid (by mass). The collector was a mixture of dodecylamine and octadecylamine in a 1:1.5 mass ratio. Five drops of the mixed amine solution were added to 500 mL of pulp. Kerosene was used as an auxiliary collector and frother; 2 mL of 98 wt% kerosene was added to 500 mL of pulp. The flotation process lasted 10 minutes. After 10 minutes, water is added to remove foam to complete the first flotation. Then, the second flotation is carried out at a water temperature of 60℃ and a pulp concentration of 30%. The pH adjuster and mixed amine are the same as in the first flotation. 3 drops of mixed amine are added to 500 mL of pulp, and 2.0 mL of 98 wt% kerosene is added to 500 mL of pulp. After 10 minutes of flotation, water is added to remove foam. After the two flotations are completed, the pulp is washed 3 times with water and placed in a high-purity quartz glass container (the container is heat resistant to temperatures above 1600℃) and dried at 90℃. The sample weight is not less than 40 g. This step takes 2 hours.

[0233] In the calcination and water quenching process, after drying, the sample was transferred to a 1200℃ heating device for calcination for 30 minutes. After calcination, the sample was transferred to 60℃ warm water (using ultrapure water with a resistivity of 18.2MΩ) for water quenching. After water quenching, the sample was transferred to a quartz container for drying and then stored in a sealed bag. This step took 2 hours.

[0234] In the acid leaching step, 20g of the roasted and water-quenched sample was weighed into a polytetrafluoroethylene beaker, and a mixed acid solution (20mL of 36% concentrated hydrochloric acid, 6mL of 40% hydrofluoric acid, and 2mL of 60% concentrated nitric acid) was added. The sample was then placed in a water bath shaker, sealed, and acid-leached for 12 hours at a water bath temperature of 60℃. The water bath process was repeatedly shaken and stirred every 2 hours. This step took 13 hours.

[0235] In the drying process, after acid leaching, the container is rinsed 6 times with ultrapure water, placed in a quartz container, dried at 90°C, and then allowed to cool naturally. This process takes 4 hours.

[0236] In the chlorination purification process, 50g of the dried sample was placed in a chlorination furnace, and chlorine gas was introduced into the pipeline. The furnace temperature was 1000℃, and chlorine gas was continuously introduced for 30min (the flow rate of chlorine gas was 0.3L / min for the first 10min, and then 0.1L / min for 20min). The tail gas was treated (the tail gas was absorbed by sodium hydroxide, and then the obtained product was evaporated and crystallized to obtain sodium chloride crystals). The sample was collected, washed with water 5 times, and dried to obtain 49.0g of 4N8 grade high-purity quartz sand. The sand was placed in a sealed bag for purification sample testing. This step took 4 hours.

[0237] The mass content of silica in the 4N8 grade high-purity quartz sand was determined using GB / T 3284-2015, and the result was 99.9983%.

[0238] The metal content in the 4N8 grade high-purity quartz sand was determined using GB / T 32649-2016. The metal content was found to be: cobalt 0.00 μg / g, nickel 0.09 μg / g, iron 0.01 μg / g, manganese 0.06 μg / g, chromium 0.00 μg / g, magnesium 0.00 μg / g, calcium 0.14 μg / g, copper 0.67 μg / g, titanium 2.64 μg / g, zirconium 0.02 μg / g, aluminum 9.52 μg / g, barium 0.01 μg / g, sodium 2.21 μg / g, lithium 0.41 μg / g, and potassium 1.18 μg / g.

[0239] Example 4

[0240] (1) Characteristics of pegmatite-type quartzite ore specimens

[0241] Specimen number: SY-08-14-34

[0242] Field identification description of the specimen: This specimen is a muscovite granite pegmatite. The rock is generally dark grayish-white and variegated, with a medium to coarse-grained granite pegmatitic texture and massive structure. The mineral composition of the rock consists of quartz, plagioclase, muscovite, and garnet. Quartz is light gray and transparent, anhedral granular, with a greasy luster, a grain size of 0.5–18 mm, and a content of 40 wt%. Plagioclase is white, subhedral to anhedral columnar granular, with a grain size of 2–42 mm. Larger feldspar grains are observed, and granular aggregates are distributed along fractures, with a content of 30 wt%. Muscovite is subhedral to euhedral platy, with a platy diameter of 1–46 mm. The muscovite is highly euhedral, with larger platy diameters, and is layered, with a content of 30 wt%. Garnet is anhedral granular, brownish-red, with a grain size of 6 mm, and is present in small quantities. Chloritization of the muscovite is observed in some areas.

[0243] (2) Identification of purified quartz sand, thin sections of rock minerals, and inclusions

[0244] The rock within the thin section is an acidic shallow to ultrashallow intrusive rock mainly composed of quartz, plagioclase, and muscovite. It exhibits a granitic pegmatitic texture and lacks directional structure. Quartz is anhedral granular, with a grain size of 0.06–5.39 mm, comprising approximately 60% of the rock. Quartz is the dominant component in the thin section. Plagioclase is subhedral columnar, with a grain size of 0.03–12.23 mm. Polysynthetic twinning is not obvious under crossed microscopes. The feldspar surface is heavily soild, comprising 25 wt%. Muscovite is subhedral platy, with a flake size of 1.52–3.12 mm. The muscovite flakes are relatively large and intact, with soild joint surfaces in some areas and localized limonite disseminated, comprising 10 wt%. The rock is argillaceous, with newly formed argillaceous minerals frequently observed along intergranular fissures. It is black, opaque, and lacks luster, comprising 5 wt%.

[0245] Figures 24-25 These are polarized microscope images of thin sections of rocks and minerals at different positions and magnifications.

[0246] Microscopic identification of inclusions:

[0247] The quartz in this sample is relatively pure, with inclusions present, but they are unevenly distributed. Fluid inclusions are more common, while solid inclusions are less frequent, accounting for 5 wt% of the quartz.

[0248] Fluid inclusions: Liquid-rich inclusions are observed, mostly spherical, elliptical, or irregular in shape, with visible gas bubbles moving randomly within them. The gas-liquid ratio is 1:3 to 1:5, and the inclusion size ranges from 0.5 to 5.5 μm. Fluid inclusions are often distributed in a skirt-like pattern along fractures, and are also found randomly at the edges of quartz grains. Fluid inclusions comprise 4 wt% of the quartz grains.

[0249] Solid inclusions: The solid inclusions are elliptical, light green, and scattered. The inclusions range in size from 4.1 to 32.1 μm and are few in number.

[0250] Inclusion particle size analysis:

[0251] Inclusions, greater than 1 μm, 90 wt%; less than 1 μm, 10 wt%.

[0252] (3) Conclusion

[0253] 1. The identification name of this thin section is muscovite granite pegmatite.

[0254] 2. The thin-sheet quartz has high overall transparency and contains inclusions, mostly of liquid-rich fluids, which are unevenly distributed. Further research on high-purity quartz is possible.

[0255] 3. After the quartz sample was crushed, its inclusion distribution was observed. The purified sand was generally clean and pure, but some purified sand showed opaque new mineral filling along the cracks, and the overall color was dark.

[0256] The specific steps for preparing 4N8 grade high-purity quartz sand are as follows:

[0257] The pegmatite-type quartz raw material is initially crushed to 1-2 cm. Take 5 kg of the initially crushed sample and first hand-sort the quartz minerals. Then, acid wash it with 10% hydrochloric acid by mass until the surface of the quartz minerals is clean and transparent without mud or other colored minerals. Then dry it. After drying, the sample is finely crushed to 120 mesh. No new impurities are introduced during the initial crushing and fine crushing process. Zirconia material processing equipment is used. After processing, the sample is immediately put into a sealed bag. The sample amount is not less than 1 kg. This step takes 2 hours.

[0258] After obtaining the finely crushed sample, it can be first subjected to weak magnetic separation once with a drum-type weak magnetic separator at a magnetic separation intensity of 0.2T, and then subjected to strong magnetic separation twice with a high gradient strong magnetic separator at a magnetic separation intensity of 1.5T. After the magnetic separation is completed, it should be sealed and stored. The amount of magnetically separated sample should not be less than 300g. This step takes 1 hour.

[0259] After magnetic separation, the samples underwent two flotation processes. The flotation water was ultrapure water with a resistivity of 18.2 MΩ, at a temperature of 55℃, with a pulp concentration of 30%. The pH was adjusted to 2 using 15% pure hydrofluoric acid (by mass). The collector was a mixture of dodecylamine and octadecylamine in a 1:2 mass ratio. Six drops of the mixed amine solution were added to 500 mL of pulp. Kerosene was used as an auxiliary collector and frother; 2 mL of 98 wt% kerosene was added to 500 mL of pulp. The flotation process lasted 10 minutes. After adding water to remove foam, the first flotation is completed. Then, the second flotation is carried out at a water temperature of 55℃ and a pulp concentration of 30%. The pH adjuster and mixed amine are the same as in the first flotation. Add 3 drops of mixed amine to 500mL of pulp and 1.0mL of 98wt% kerosene to 500mL of pulp. After flotation for 10 minutes, add water to remove foam. After the two flotations are completed, rinse with water 3 times and put into a high-purity quartz glass container (the container can withstand temperatures above 1600℃) and dry at 90℃. The sample amount is not less than 40g. This step takes 2 hours.

[0260] In the roasting and water quenching process, after drying, the sample was transferred to a heating device at 1300℃ for roasting for 30 minutes. After roasting, the sample was transferred to 60℃ warm water (using ultrapure water with a resistivity of 18.2MΩ) for water quenching. After water quenching, the sample was transferred to a quartz container for drying and then stored in a sealed bag. This step took 2 hours.

[0261] In the acid leaching step, 20g of the roasted and water-quenched sample was weighed into a polytetrafluoroethylene beaker, and a mixed acid solution (20mL of 36% concentrated hydrochloric acid, 6mL of 40% hydrofluoric acid, and 2mL of 60% concentrated nitric acid) was added. The sample was then placed in a water bath shaker, sealed, and acid-leached for 12 hours at a water bath temperature of 60℃. The water bath process was repeatedly shaken and stirred every 2 hours. This step took 13 hours.

[0262] In the drying process, after acid leaching, the container is rinsed 6 times with ultrapure water, placed in a quartz container, dried at 90°C, and then allowed to cool naturally. This process takes 4 hours.

[0263] In the chlorination purification process, 50g of the dried sample was placed in a chlorination furnace, and chlorine gas was introduced into the pipeline. The furnace temperature was 1200℃, and chlorine gas was continuously introduced for 30min (the flow rate of chlorine gas was 0.3L / min for the first 10min, and then 0.1L / min for 20min). The tail gas was treated (the tail gas was absorbed by sodium hydroxide, and then the obtained product was evaporated and crystallized to obtain sodium chloride crystals). The sample was collected, washed with water 5 times, and dried to obtain 48.7g of 4N8 grade high-purity quartz sand. The sand was placed in a sealed bag for purification sample testing. This step took 4 hours.

[0264] The mass content of silica in the 4N8 grade high-purity quartz sand was determined using GB / T 3284-2015, and the result was 99.9981%.

[0265] The metal content in the 4N8 grade high-purity quartz sand was determined using GB / T 32649-2016. The contents of cobalt, nickel, iron, manganese, chromium, magnesium, calcium, copper, titanium, zirconium, aluminum, barium, sodium, lithium, and potassium were 0.69 μg / g.

[0266] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for screening potential raw materials of pegmatite-type quartz, characterized in that, Includes the following steps: The first screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Quartz inclusions accounting for less than 5% of the quartz grain area and having a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers. Alternatively, quartz inclusions in which more than 70% are distributed at the edge of fractures or at different depths simultaneously do not exceed 30% and have a gas-liquid phase volume ratio of more than 80% are used as preliminary potential sample identifiers. The second screening criterion is to detect the characteristics of quartz inclusions in pegmatite geological inclusions. Based on the quartz inclusions with a diameter of no more than 125 μm, the proportion of inclusions with a diameter of less than 1 μm in the quartz inclusions is less than 20%, which is used as a preliminary potential sample identifier. The third screening criterion is to detect the titanium content in the pegmatite, with a titanium content ≤10ppm indicating a potential sample. Once a sample to be screened meets the first screening criteria and / or the second screening criteria and is determined to be a preliminary potential sample, the preliminary potential sample is then judged according to the third screening criteria. The sample that meets the third screening criteria is the potential raw material of pegmatite-type quartz.

2. The screening method according to claim 1, characterized in that, The titanium content in the pegmatite was obtained by cathodic fluorescence spectroscopy. The titanium content ≤10ppm means that the spectral intensity at wavelengths of 350~500nm in the cathodic fluorescence spectrum is ≤100 counts.

3. The screening method according to claim 1, characterized in that, The following selection criteria are also included: The fourth screening criterion is to determine the potential samples by observing the color of the quartz particles in the pegmatite. The color of the quartz particles is colorless and transparent or light smoky gray. The light smoky gray is Pantone Cool Gray 1C~9C in the Pantone color chart. The fifth screening criterion is to detect whether rare elements exist in the pegmatite mineralization belt, with samples that do not contain rare metals being identified as potential samples. The sixth screening criterion is to test the mineral composition of the pegmatite. Potential samples are identified by the bright color of the muscovite, the full lamellar structure, the garnet content not exceeding 2% by mass, and the absence of rutile. The seventh screening criterion is to observe the mosaic characteristics of pegmatite geological thin sections, and to identify potential samples with loose bonding of quartz, feldspar, and mica, clear edges of the external shape of quartz, distinct separation of quartz, mica, and feldspar, and no mutual mosaic relationship. The eighth screening criterion: observe the mineral composition of pegmatite geological thin sections, and identify potential samples with a reflectance of ≥60% at a wavelength of 550nm under a microscope, euhedral crystals, and a gray value of ≥200; Ninth screening criterion: Observe the oil-immersed sections of pegmatite inclusions, and identify potential samples with an inclusion area of ​​less than 5% in the oil-immersed sections of pegmatite inclusions; The tenth screening criterion: Detect the degree of cracking in the quartz particles within the pegmatite, and identify potential samples with a surface crack area ratio of ≤2% for the quartz particles; Those that meet more than 5 of the fourth to tenth screening criteria are considered potential raw materials for pegmatite-type quartz.

4. The screening method according to claim 3, characterized in that, Those that meet the first to tenth screening criteria are considered potential raw materials for pegmatite-type quartz.

5. The screening method according to claim 3, characterized in that, The rare elements include Li and Be.

6. A method for preparing 4N8 grade high-purity quartz sand, characterized in that, Includes the following steps: Using the screening method described in any one of claims 1 to 5, potential raw materials of pegmatite-type quartz can be obtained; The pegmatite-type quartz potential raw material is subjected to crushing, acid washing, weak magnetic separation, strong magnetic separation, flotation, roasting and water quenching, acid leaching, drying and chlorination purification in sequence to obtain the 4N8 grade high-purity quartz sand. The magnetic field strength of the weak magnetic separation is 0.1~0.5T and the magnetic field strength of the strong magnetic separation is 1.5~1.7T.

7. The preparation method according to claim 6, characterized in that, The collectors used in the flotation process include dodecylamine and octadecylamine, and the mass ratio of dodecylamine to octadecylamine in the collector is 1:1.5~2.

8. The preparation method according to claim 6, characterized in that, The roasting temperature during the roasting and water quenching process is 1000~1500℃, and the time is 0.5~1h. The water quenching temperature during the roasting and water quenching process is 50~80℃, and the time is 0.5~1min.

9. The preparation method according to claim 6, characterized in that, The mixed acid used in the acid leaching includes concentrated hydrochloric acid, hydrofluoric acid, and concentrated nitric acid. The mass concentration of the concentrated hydrochloric acid is 36% to 38%, the mass concentration of the concentrated nitric acid is 40% to 68%, and the mass concentration of the hydrofluoric acid is 35% to 45%. The volume ratio of the concentrated hydrochloric acid, hydrofluoric acid, and concentrated nitric acid in the mixed acid is 20:6:

2.

10. The preparation method according to claim 6, characterized in that, The chlorination purification is carried out at a temperature of 1000~1400℃ for a time of 0.5~1h, and is conducted in chlorine or hydrogen chloride gas.

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