Preparation method of high-purity quartz sand with high permeability

Abstract

The present application relates to a method for preparing high-purity quartz sand with high permeability, belonging to the field of mineral processing and purification, using quartz raw sand or concentrate sand after beneficiation as raw material, comprising the following steps: laminating self-crushing, low-temperature calcination-water quenching treatment of quartz raw sand or concentrate sand after beneficiation, then using single hydrofluoric acid leaching treatment; adding hydrochloric acid and nitric acid on the basis of hydrofluoric acid system, carrying out ternary acid system leaching; using water washing-drying treatment on the leaching product, obtaining high-purity quartz sand with high permeability. Compared with the traditional method, the permeability of the quartz glass melt of the present application far exceeds that of the high-purity quartz sand obtained by conventional technology, using the high-purity quartz sand of the present application to prepare a 12-inch high-purity quartz crucible, the crucible slice shows obvious transparent layer, the whole is uniform, the boundary is clear, the bubble degree (mm 2 ) < 140, and the transparency (%) > 90.

Description

Technical Field

[0001] This invention relates to a method for preparing high-purity quartz sand with high transparency, belonging to the field of mineral processing and purification. Background Technology

[0002] High-purity quartz is an essential industrial raw material for many high-tech industries, with applications including high-purity quartz glass, optical fibers, and crucibles for semiconductors. The purity of high-purity quartz raw materials directly determines the physicochemical properties and application value of its products. Generally, the market price of high-purity quartz increases exponentially with the quality of the raw material. Fluid inclusions in existing high-purity quartz sand are gas-liquid mixtures trapped during crystal growth, significantly affecting purity and high-temperature processing performance. Currently, the mainstream removal method is mainly thermal activation combined with chemical leaching, supplemented by physical sorting and novel auxiliary processes, to achieve varying degrees of removal. While conventional techniques improve the purity of high-purity quartz sand after removing fluid inclusions, the presence of numerous positional cavities and pits within the quartz sand leads to the generation of numerous microbubbles within the quartz glass during subsequent melting, severely impacting the optical, thermal stability, mechanical strength, and resistance to crystallization of the quartz glass. Therefore, conventional techniques only remove fluid inclusions. Acid leaching cannot allow acid to enter these enclosed spaces, resulting in internal impurities not being removed. It does not eliminate cavities and blind ends, and does not significantly improve the transparency and uniformity of high-purity quartz glass. Summary of the Invention

[0003] This invention provides a method for preparing high-purity quartz with high transparency, which solves the problem that existing methods remove fluid inclusions and effectively improve the purity of quartz sand, but do not eliminate vacancy blind ends, resulting in high-purity quartz sand with poor optical properties.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing high-purity quartz sand with high transparency, using raw quartz ore sand or concentrate sand after beneficiation as raw material, includes the following steps: (1) Quartz raw ore sand or concentrate sand after beneficiation is laminated and self-crushed to obtain a specific surface area of ​​0.02m². 2 / g-0.03m 2 / g of quartz sand; (2) The quartz sand is subjected to low-temperature calcination-water quenching treatment, with the calcination temperature at 200℃-300℃ and the water quenching temperature at 0℃-20℃; (3) The product after calcination and water quenching is first subjected to single hydrofluoric acid leaching treatment; (4) Add hydrochloric acid and nitric acid to the leaching system in step (3) to carry out leaching of the tribasic acid system; (5) The leaching product is subjected to water washing-drying treatment to obtain high-purity quartz sand with high transparency.

[0005] Furthermore, preferably, the quartz ore sand or the concentrate sand after beneficiation has a SiO2 purity of 99.95%-99.99% and a particle size range of 40 mesh-160 mesh.

[0006] Furthermore, preferably: the lamination self-crushing process employs a high-pressure roller mill with a roller surface pressure of 4 N / mm. 2 -6 N / mm 2 .

[0007] Furthermore, preferably, the low-temperature calcination time for the low-temperature calcination-water quenching treatment is 10-20 min.

[0008] Furthermore, preferably, the single hydrofluoric acid leaching treatment is as follows: hydrofluoric acid concentration 40-45%, acid leaching temperature 80℃, liquid-solid ratio 1:1, and leaching time 2-3 hours.

[0009] Furthermore, preferably: the leaching of the tribasic acid system specifically involves a hydrochloric acid concentration of 10%-15%, a nitric acid concentration of 1%-2%, a liquid-to-solid ratio of 1:1-2:1, a leaching temperature of 80°C, and a leaching time of 3-5 hours.

[0010] The beneficial effects of this invention are: The method of this invention first involves lamination and self-crushing, with the specific surface area of ​​the self-crushing product controlled at 0.02 m². 2 / g-0.03m 2 / g, compared with the original feed sand, the particle size did not change significantly, but the specific surface area increased significantly, which caused a large number of microcracks to be generated inside the quartz sand, opening up the fluid inclusion defects inside the quartz particles. The laminated self-crushing product undergoes low-temperature calcination and water quenching, with a specific surface area controlled at 0.05 m². 2 / g- 0.08m 2 / g, through the repeated addition of thermal stress and shrinkage stress, microcracks of micron or even nanometer scale are generated at the interface between the originally closed inclusion and the quartz matrix, or at the fragile parts of the inclusion itself. These microcracks are like blasting open tiny channels to the outside world on the wall of the hole blind end, creating physical conditions for the subsequent entry of acid. Low temperature operation avoids the melting of the inclusion or the diffusion of impurities into the depth of the quartz lattice at high temperature. After calcination and water quenching, the product is first leached with hydrofluoric acid. Hydrofluoric acid not only dissolves silicate impurities in the inclusions, but it also corrodes the quartz matrix itself along the microcracks, acting as a chemical excavator and widening channel. This transforms the microcracks from physical channels into chemical erosion channels, making it easier for the acid to penetrate the quartz sand and effectively preventing other acids from reacting with impurities prematurely to form insoluble substances that block the newly opened channels. Hydrochloric acid and nitric acid are then added to the original leaching system for a ternary acid leaching system. The acid mixture, through the opened and widened channels, fully contacts various impurities inside the inclusions, efficiently dissolving metal oxides, silicate minerals, and even some insoluble substances. It also complexes, oxidizes, dissolves, and carries out impurity ions inside the cavities, achieving deep purification and effectively improving the optical properties of the quartz sand.

[0011] Through the processing method of this invention, the fluid encapsulation inside the quartz sand is penetrated by sub-macroscopic cracks, solving the problem of vacancy blind ends and significantly reducing the microbubble content of the subsequent quartz glass. Compared with traditional methods, the transparency of the quartz glass melt of this invention far exceeds that of high-purity quartz sand obtained by conventional techniques. When using the high-purity quartz sand of this invention to prepare a 12-inch high-purity quartz crucible, the crucible slices show a clear transparent layer, are uniform overall, have clear boundaries, and have a low bubble density (mm). 2 <140, transparency (%) >90. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 Hand specimen of granite pegmatite; Figure 2 This is a diagram showing the internal crack development of quartz in Example 1; Figure 3 This is a characteristic diagram of fluid inclusions inside quartz particles in Example 1; Figure 4 This is a surface feature diagram of quartz beneficiation concentrate sand before lamination and crushing. Figure 5 This is a surface feature diagram of quartz beneficiation concentrate sand after lamination and crushing; Figure 6 This is a surface feature diagram of the quartz particles after purification in Example 1; Figure 7 This is a surface feature diagram of quartz particles after calcination and acid leaching purification, as shown in Comparative Example 1. Figure 8The high-purity quartz sand oil-impregnated sheets are from Example 1 and Comparative Example 1; Figure 9 Photographs of the sealed fused silica glass bodies after processing in Example 1 and Comparative Example 1; Figure 10 Photographs of 12-inch high-purity quartz crucible sections from Example 1 and Comparative Example 1; Figure 11 These are high-purity quartz sand oil-impregnated sheets from Example 2 and Comparative Example 2; Figure 12 Photographs of the sealed fused silica glass bodies after processing in Example 2 and Comparative Example 2; Figure 13 Photographs of 12-inch high-purity quartz crucible sections from Example 2 and Comparative Example 2. Detailed Implementation

[0014] The technical solutions of this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. 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.

[0015] The high-purity quartz sand used in Example 1 and Comparative Example 1 of this invention is as follows: a granite pegmatite from Xinjiang, the sample hand specimen is shown below. Figure 1 The lithology is muscovite granite pegmatite, with locally visible euhedral garnets. The sample is grayish-white overall, with a holocrystalline and pegmatitic texture and a massive structure.

[0016] The sample contained minerals including quartz (20%–25%), plagioclase (65%–70%), muscovite (~3%), potassium feldspar (~1%), and garnet (~1%). Quartz appeared colorless and transparent under polarized light, and cracks were commonly found within the grains. Figure 2 (As shown). Under crossed polarized light, it appears as a subhedral to anhedral granular structure. Wavy extinction is commonly observed. Some grains contain muscovite inclusions, while others show quartz grains encased in plagioclase. Grain size varies, ranging from approximately 0.2 to 10 mm.

[0017] like Figure 3 As shown, fluid inclusions are developed within the quartz grains, exhibiting surface, cluster, banded, and linear distributions, with surface and cluster distributions being more common. They are numerous. Types include two-phase (gas-liquid), pure gas, and pure liquid inclusions, with the gas-liquid two-phase being the most prevalent. The gas-liquid two-phase inclusions are irregular in shape, nearly elliptical, and approximately 5–20 μm in size. Mineral inclusions are elongated columnar, rare, and approximately 20–50 μm in length and diameter.

[0018] The impurity elements of the quartz concentrate sand after beneficiation of the raw ore sample are shown in Table 1. The SiO2 purity is 99.97%, and the particle size is -40 to +160 mesh.

[0019] Table 1. Characteristic Table of Impurity Elements in Quartz Concentrate Sand

[0020] The SEM (scanning electron microscope) image of the mineral concentrate of this sample shows (e.g.) Figure 4 As shown in the figure, the particle surface is smooth with few cracks.

[0021] Example 1 A method for preparing high-purity quartz sand with high transparency, using the quartz beneficiation concentrate sand in Table 1 as raw material, includes the following steps: (1) The quartz concentrate sand is subjected to lamination and crushing. The lamination and crushing adopts a high-pressure roller mill with a roller surface pressure of 4.5 N / mm. 2 SEM images of the quartz sand powder after lamination and crushing (e.g.) Figure 5 As shown), by Figure 4 and 5 It can be seen that, compared with untreated quartz sand, the lamination process does not significantly affect the particle size of quartz particles, resulting in smaller particles. Furthermore, the compaction of the material layer creates a multi-directional stress field, causing the quartz sand particles to fracture at weak points and generate numerous microcracks. Fluid inclusions within the quartz are stress-weak areas, easily generating micropores and connecting through them to form microcracks under lamination self-crushing, which facilitates the subsequent removal of fluid inclusions. The specific surface areas before and after lamination, measured using the BET adsorption method, are shown in Table 2.

[0022] Table 2. Specific surface area results before and after lamination and crushing.

[0023] (2) The quartz sand powder was subjected to low-temperature calcination-water quenching treatment. The calcination temperature was 280℃ and the time was 15min. The water quenching temperature was 20℃.

[0024] (3) The product after calcination and water quenching is first treated with hydrofluoric acid leaching with a concentration of 40% hydrofluoric acid, an acid leaching temperature of 80℃, a liquid-solid ratio of 1:1, and a leaching time of 2 hours.

[0025] (4) Based on the leaching system in step (3), add a mixture of hydrochloric acid and nitric acid to carry out leaching of the tribasic acid system. The concentration of hydrochloric acid in the mixed acid is 15%, the concentration of nitric acid is 1%, the liquid-solid ratio is 2:1, the leaching temperature of the tribasic acid system is 80℃, and the leaching time is 4 hours.

[0026] (5) The leaching product is subjected to water washing-drying treatment to obtain high-purity quartz sand with high transparency.

[0027] Comparative Example 1 A method for preparing high-purity quartz sand with high transparency, using the quartz beneficiation concentrate sand in Table 1 as raw material, includes the following steps: (1) Quartz beneficiation concentrate sand is purified by conventional calcination-acid leaching technology. The calcination temperature is 1050℃ for 30min and the water quenching temperature is 20℃. (2) The product after calcination and water quenching is leached with a tribasic acid system using a mixture of hydrofluoric acid, hydrochloric acid and nitric acid. The concentration of hydrofluoric acid in the mixture is 20%, the concentration of hydrochloric acid is 10%, the concentration of nitric acid is 1%, the liquid-solid ratio is 2:1, the leaching temperature of the tribasic acid system is 80℃, and the leaching time is 6 hours. (3) The leaching product is subjected to water washing-drying treatment to obtain high-purity quartz sand with high transparency.

[0028] Performance testing of purified high-purity quartz sand: (1) SEM images Example 1: SEM image of the purified sample. Figure 6 As shown, the SEM image after purification in Comparative Example 1 is as follows. Figure 7 As shown, by Figure 6 and 7 It can be seen that the quartz sand particles treated with high-temperature calcination-water quenching-one-step acid leaching produced fewer microcracks and had obvious traces of mixed acid erosion on the surface; the quartz sand particles treated with low-temperature calcination-water quenching-two-step acid leaching had fully developed microcracks on the surface, and some microcracks formed sub-macro-cracks after low-temperature calcination-water quenching and mixed acid erosion, and formed connections and penetrations, and also had obvious traces of mixed acid erosion on the surface.

[0029] (2) Oil-impregnated slices Quartz sand was evenly dispersed on a glass slide, covered with a coverslip, and then oil was added to prepare an oil-impregnated slide. The inclusions within the quartz particles were then observed using a polarizing microscope. Images of oil-impregnated slides of high-purity quartz sand products using different processing techniques are shown below. Figure 8 As shown, the quartz sand in Example 1 is loose internally with obvious sub-macroscopic cracks running through it, and the quartz particles are generally transparent. In contrast, the quartz sand in Comparative Example 1 is dense internally, with microcracks visible around the particles, but these cracks have not yet extended into the interior. Compared to the raw material (e.g., ...), the quartz sand in Comparative Example 1 is dense internally, with microcracks visible around the particles, but these cracks have not yet extended into the interior. Figure 3 Due to the large-scale bursting of the inclusions, its optical characteristics exhibit large areas of shadow, significant hole blind-end effect, and poor transparency.

[0030] (3) High-purity quartz sand was used for a sealing and melting test. High-purity quartz sand was placed in a quartz glass test tube and fused to a molten state using an oxyhydrogen flame generated by a vacuum glass sealing machine. After cooling, a high-purity molten quartz glass body was obtained. Tube-sealing melting tests were conducted to evaluate high-purity quartz sand treated with different techniques, such as... Figure 9 As shown. By Figure 9 It can be seen that the transparency of the quartz glass melt prepared in Example 1 is much greater than that of Comparative Example 1.

[0031] (4) Measurement of transparency of high-purity quartz A 12-inch high-purity quartz crucible was prepared using high-purity quartz sand processed with different techniques. The preparation process was as follows: high-purity quartz sand was loaded into a rotary molding die that could be tilted at any angle; then, using centrifugal force and manual shaping with a molding rod, the pre-formed rotary device was moved to the electrode rod; next, the electrode was energized and inserted into the pre-formed powder cavity, while simultaneously activating the vacuum system to rapidly melt it into molten quartz in the shape of a crucible; finally, after cooling, it was removed, completing a blank of a quartz crucible. Crucible slices are shown below. Figure 10 As shown in Table 3, its transmittance and bubble density are as follows. Figure 10 As can be seen, the crucible slice of Example 1 exhibits a distinct transparent layer, is uniform overall, and has clear boundaries. The crucible slice of Comparative Example 1 does not yet show a transparent layer. The inner layer of the crucible slice of Example 1 shows significantly better performance than that of Comparative Example 1 in terms of both bubble density and light transmittance.

[0032] Table 3. Transparency index of the inner layer of 12-inch high-purity quartz crucible slices after different treatment techniques.

[0033] (5) Determination of specific surface area of ​​quartz particles The specific surface area of ​​quartz particles purified by different treatment methods was tested and analyzed using the BET adsorption method, as shown in Table 4.

[0034] Table 4. Specific surface area of ​​quartz particles during purification processes using different treatment methods.

[0035] (6) Purity determination of different products The purity of the products after purification by different technologies is shown in Table 5. The total amount of 17 impurity elements after purification in Example 1 is 14.93 ppm. The SiO2 purity of the high-purity quartz sand after purification by the new technology is 99.9985%, which is 4.8 ppm higher than that of conventional technology. The difference in purity between the two is not significant.

[0036] Table 5. Purity of high-purity quartz sand obtained through different purification techniques

[0037] Example 2 and Comparative Example 2 used vein quartz sand as raw material. The SiO2 purity of the vein quartz sand was 99.984%, the particle size was -40 to +160 mesh, and the content of the main impurity elements is shown in Table 6.

[0038] Table 6. Characteristic Table of Impurity Elements in Vein Quartz-Type Quartz Sand

[0039] Example 2 A method for preparing high-purity quartz sand with high transparency, using vein quartz-type quartz sand from Table 6 as raw material, includes the following steps: (1) The quartz concentrate sand is subjected to lamination and crushing. The lamination and crushing adopts a high-pressure roller mill with a roller surface pressure of 6 N / mm. 2 ; (2) The quartz sand powder was subjected to low-temperature calcination-water quenching treatment. The calcination temperature was 200℃ and the time was 20min. The water quenching temperature was 0℃. (3) The product after calcination-water quenching is first treated with single hydrofluoric acid leaching. The hydrofluoric acid concentration is 45%, the acid leaching temperature is 80℃, the liquid-solid ratio is 1:1, and the leaching time is 3 hours. (4) Based on the leaching system in step (3), add a mixture of hydrochloric acid and nitric acid to carry out leaching of the tribasic acid system. The concentration of hydrochloric acid in the mixture is 10%, the concentration of nitric acid is 2%, the liquid-solid ratio is 1:1, the leaching temperature of the tribasic acid system is 80℃, and the leaching time is 3 hours. (5) The leaching product is subjected to water washing-drying treatment to obtain high-purity quartz sand with high transparency.

[0040] Comparative Example 2 Using the quartz beneficiation concentrate sand in Table 6 as raw material, the specific steps are the same as those in Comparative Example 1.

[0041] The properties of the quartz sand prepared in Example 2 and Comparative Example 2 were measured, and the results are as follows: (1) Oil-impregnated slices Quartz sand was evenly dispersed on a glass slide, covered with a coverslip, and then oil was added to prepare an oil-impregnated slide. The inclusions within the quartz particles were then observed using a polarizing microscope. Oil-impregnated slides of high-purity quartz sand products produced using different technologies are shown below. Figure 11 As shown, the quartz sand in Example 2 is loose internally with obvious sub-macroscopic cracks running through it, and the quartz particles are generally transparent. In contrast, the quartz sand in Comparative Example 2 is dense internally, with microcracks visible around the particles, but the cracks have not yet extended into the interior. Due to the large number of inclusions bursting, its optical characteristics show large areas of shadows, a significant vacancy blind-end effect, and poor transparency.

[0042] (2) High-purity quartz sand was used for a sealing and melting test. High-purity quartz sand was placed in a quartz glass test tube and fused to a molten state using an oxyhydrogen flame generated by a vacuum glass sealing machine. After cooling, a high-purity molten quartz glass body was obtained. Tube-sealing melting tests were conducted to evaluate high-purity quartz sand treated with different techniques, such as... Figure 12 As shown. By Figure 12 It can be seen that the transparency of the quartz glass melt prepared in Example 2 is much greater than that of Comparative Example 2.

[0043] (3) Measurement of transparency of high-purity quartz High-purity quartz sand treated with different techniques was prepared using a 12-inch high-purity quartz crucible. Crucible slices are shown below. Figure 13 As shown in Table 7, its transmittance and bubble density are as follows. Figure 13 It can be seen that the crucible slice of Example 2 has a clear transparent layer, is uniform overall, and has clear boundaries, while the crucible slice of Comparative Example 2 has not yet shown a transparent layer.

[0044] Table 7. Transparency Index of Inner Layer of 12-inch High-Purity Quartz Crucible Slices After Different Treatment Techniques

[0045] Although embodiments of the present invention have been described above, any modifications and substitutions made by those skilled in the art without departing from the principles and spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing high-purity quartz sand with high transparency, characterized in that, Using raw quartz ore or beneficiated concentrate as raw material, the process includes the following steps: (1) Quartz raw ore sand or concentrate sand after beneficiation is laminated and self-crushed to obtain a specific surface area of ​​0.02m². 2 / g-0.03m 2 / g of quartz sand; (2) The quartz sand is subjected to low-temperature calcination-water quenching treatment, with the calcination temperature at 200℃-300℃ and the water quenching temperature at 0℃-20℃; (3) The product after calcination and water quenching is first subjected to single hydrofluoric acid leaching treatment; (4) Add hydrochloric acid and nitric acid to the leaching system in step (3) to carry out leaching of the tribasic acid system; (5) The leaching product is subjected to water washing-drying treatment to obtain high-purity quartz sand with high transparency.

2. The preparation method according to claim 1, characterized in that: The quartz ore sand or the concentrate sand after beneficiation has a SiO2 purity of 99.95%-99.99% and a particle size range of 40 mesh-160 mesh.

3. The preparation method according to claim 1, characterized in that: The aforementioned lamination self-crushing process utilizes a high-pressure roller mill with a roller surface pressure of 4 N / mm. 2 -6 N / mm 2 .

4. The preparation method according to claim 1, characterized in that: The low-temperature calcination time for the low-temperature calcination-water quenching treatment is 10-20 min.

5. The preparation method according to claim 1, characterized in that: The specific hydrofluoric acid leaching treatment is as follows: hydrofluoric acid concentration 40-45%, acid leaching temperature 80℃, liquid-solid ratio 1:1, and leaching time 2-3 hours.

6. The preparation method according to claim 1, characterized in that: The leaching of the tribasic acid system specifically involves a mixed acid concentration of 10%-15% hydrochloric acid, a nitric acid concentration of 1%-2%, a liquid-to-solid ratio of 1:1-2:1, a leaching temperature of 80℃, and a leaching time of 3-5 hours.

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