A method for preparing high-purity quartz by deep calcination of additives and high-purity quartz

Abstract

This invention provides a method for preparing high-purity quartz through deep impurity removal by calcination with additives, and the high-purity quartz itself. The method includes: crushing, grinding, and screening raw quartz powder to obtain coarse quartz powder particles; performing reverse flotation on the coarse quartz powder particles to obtain first quartz particles; subjecting the first quartz particles to a first acid leaching to obtain second quartz particles; mixing the second quartz particles with a calcination additive and then calcining to obtain third quartz particles; and subjecting the third quartz particles to a second acid leaching, water washing, and drying to obtain high-purity quartz. The high-purity quartz prepared by the above method has an SiO2 content greater than 99.9%, reaching a maximum of 99.995%. The method of this invention is simple and can effectively remove trace amounts of inert impurities. The high-purity quartz of this invention can be widely used in fields including quartz glass, large-scale integrated circuits, and solar cells.

Description

Technical Field

[0001] This invention relates to the field of quartz purification technology, specifically to a method for preparing high-purity quartz by deep impurity removal through calcination of additives, and the high-purity quartz thereof. Background Technology

[0002] Powdered quartz is a widely distributed natural quartz resource in my country. It naturally occurs as a powder and is considered a high-quality industrial silica raw material. While primarily composed of quartz, powdered quartz typically contains impurities such as iron and clay, resulting in lower purity. Due to the diverse types and difficulty in characterizing the fine-grained mineral impurities introduced during natural weathering, common quartz purification methods are insufficient for guiding the high-purity production of powdered quartz, thus hindering the high-value development and utilization of this resource.

[0003] Currently, the purification of powdered quartz faces challenges such as high purification difficulty, high energy consumption, and limited effectiveness in removing trace inert impurities. Therefore, providing a method for deep impurity removal using additives through calcination to prepare high-purity quartz is of significant importance. Summary of the Invention

[0004] The purpose of this invention is to address at least one of the aforementioned shortcomings of the prior art. For example, one objective of this invention is to provide an environmentally friendly, simple, and effective method for preparing high-purity quartz through deep impurity removal by calcination of additives, which can effectively remove trace amounts of inert impurities. Another objective of this invention is to provide high-purity quartz that can be widely used in fields including quartz glass, large-scale integrated circuits, optical fibers, and solar cells.

[0005] To achieve the above objectives, the present invention provides a method for preparing high-purity quartz by deep purification through roasting with an additive. The method may include: pretreating powdered quartz ore to obtain first quartz particles; subjecting the first quartz particles to a first acid leaching to obtain second quartz particles; mixing the second quartz particles with a roasting additive and then roasting to obtain third quartz particles; subjecting the third quartz particles to a second acid leaching, followed by filtration, washing, and drying to obtain high-purity quartz.

[0006] According to one or more exemplary embodiments of one aspect of the present invention, the calcination aid may include one or both of ammonium sulfate and ammonium bisulfate; the calcination aid and the second quartz particles may be mixed uniformly in a mass ratio of 0.1 to 0.3; the calcination temperature may be 450 to 550°C; and the calcination time may be 60 to 120 minutes.

[0007] According to one or more exemplary embodiments of one aspect of the present invention, the pretreatment may include: crushing, grinding and screening the raw quartz powder to obtain coarse quartz powder particles of -200 mesh to +500 mesh; and performing reverse flotation on the coarse quartz powder particles to obtain first quartz particles.

[0008] Furthermore, the crushing process can employ one or more of the following: toothed roll crusher, double roll crusher, jaw crusher, gyratory crusher, and cone crusher.

[0009] According to one or more exemplary embodiments of one aspect of the present invention, the reverse flotation may include: adjusting coarse quartz powder particles into a slurry with a concentration of 20-50%; adjusting the pH of the slurry to 1.0-2.5; adding a cationic amine collector, performing reverse flotation treatment to remove some impurity minerals; collecting the reverse flotation concentrate and washing it with water until the pH of the filtrate is 7, and then filtering it to obtain the first quartz particles.

[0010] Furthermore, in the reverse flotation process, industrial water can be used to adjust the coarse quartz powder particles into a slurry; in the reverse flotation process, hydrofluoric acid can be used to adjust the pH of the slurry; the cationic amine collector may include one or more of dodecylamine, hexadecylamine and octadecylamine, and the dosage may be 100-200 g / t.

[0011] According to one or more exemplary embodiments of one aspect of the present invention, the first acid leaching may include: mixing first quartz particles with a first acid leaching solution at a liquid-to-solid ratio of 3–6 L / kg; the first acid leaching solution contains hydrofluoric acid at a molar concentration of 2–8 mol / L, oxalic acid at a molar concentration of 0.2–0.8 mol / L, hydrochloric acid at a molar concentration of 0.5–5 mol / L, and nitric acid at a molar concentration of 0.2–1 mol / L; the first acid leaching temperature is 50–90°C; the first acid leaching time is 2–4 h; after the first acid leaching reaction is completed, the acid leaching product is filtered and washed until the pH of the filtrate is 7, and second quartz particles are obtained after filtration; the second quartz particles have a water content of 10%–15%.

[0012] According to one or more exemplary embodiments of one aspect of the present invention, the second acid leaching may include: mixing third quartz particles with a second acid leaching solution at a liquid-to-solid ratio of 6–14 L / kg; the molar concentration of hydrofluoric acid in the second acid leaching solution being 0.8–2 mol / L and the molar concentration of hydrochloric acid being 0.2–1 mol / L; the temperature of the second acid leaching being 50–90°C; the time of the second acid leaching being 2–4 h; and after the second acid leaching reaction is completed, filtering and washing until the pH of the filtrate is 7, followed by drying to obtain high-purity quartz.

[0013] According to one or more exemplary embodiments of one aspect of the present invention, the minerals contained in the powdered quartz ore may include quartz, as well as one or more of magnetite, talc, mica and feldspar.

[0014] According to one or more exemplary embodiments of one aspect of the present invention, the third quartz particle may include quartz, and one or more soluble sulfates selected from aluminum sulfate, magnesium sulfate, calcium sulfate and ferric sulfate formed by the reaction.

[0015] Another aspect of the present invention provides a high-purity quartz, which may include a product prepared by the method of preparing high-purity quartz by deep impurity removal through calcination with the above-described additives, wherein the SiO2 content in the high-purity quartz may be 99.9% to 99.995%, and the particle size of the high-purity quartz particles may be -200 mesh to +500 mesh.

[0016] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0017] (1) The method for preparing high-purity quartz by deep purification through calcination of additives proposed in this invention can preferentially expose the inclusions in the powdered quartz through the first acid leaching, and can effectively remove inert impurities through calcination of additives and second acid leaching, showing a good purification effect of powdered quartz.

[0018] (2) The method for preparing high-purity quartz by deep calcination of additives proposed in this invention can achieve a quartz product purity of over 99.9%, a Mg ion removal rate of over 99%, and an Al ion removal rate of over 90%. Furthermore, this process can be combined with other high-purity quartz preparation processes to achieve better purification effects, such as microwave bursting, hot pressing acid leaching, segregation etch, and other purification processes.

[0019] (3) The high-purity quartz proposed in this invention has a purity of over 99.9%, and can reach up to 99.995%, and can be widely used in industries including quartz glass, large-scale integrated circuits, optical fibers, solar cells and aerospace materials. Attached Figure Description

[0020] The above and other objects and features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 A process flow diagram of a method for preparing high-purity quartz by deep impurity removal through calcination of additives, according to an exemplary embodiment of the present invention, is shown.

[0022] Figure 2 The XRD pattern of the raw quartz powder of Example 1 of the present invention is shown;

[0023] Figure 3The XRD pattern of the final product of Example 1 of the present invention, high-purity quartz, is shown. Detailed Implementation

[0024] The method for preparing high-purity quartz by deep calcination of additives according to the present invention, and the high-purity quartz thereof, will be described in detail below with reference to the accompanying drawings and exemplary embodiments.

[0025] In the description of this application, it should be understood that the terms "first," "second," "third," etc., are merely for convenience of description and distinction, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "multiple" means two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Exemplary Example 1

[0027] This exemplary embodiment provides a method for preparing high-purity quartz by deep impurity removal through calcination of additives.

[0028] Figure 1 A process flow diagram of a method for preparing high-purity quartz by deep impurity removal through calcination of additives, according to an exemplary embodiment of the present invention, is shown below. Figure 1 This exemplary embodiment describes a method for preparing high-purity quartz by deep calcination of additives to remove impurities.

[0029] like Figure 1 As shown, the process steps of the method for preparing high-purity quartz by deep purification through additive roasting may include: crushing, grinding, and screening the raw quartz ore in sequence; then classifying it, performing reverse flotation on the obtained particles of 200-500 mesh, and grinding and screening the particles larger than 200 mesh again; in the reverse flotation stage, reverse flotation concentrate and gangue minerals such as talc are obtained separately, and the reverse flotation concentrate is subjected to a first acid leaching, additive roasting, and a second acid leaching in sequence to obtain high-purity quartz. The second acid leaching filtrate obtained during the second acid leaching process can be diluted and / or added to mixed acid and recycled into the first acid leaching stage.

[0030] The process for preparing high-purity quartz through deep impurity removal via calcination of additives can be summarized as a combined process of first acid leaching, additive calcination, and second acid leaching. First acid leaching dissolves most impurities adhering to the quartz surface and independent gangue minerals, while simultaneously corroding weak points on the quartz surface, exposing defective areas. Additive calcination involves the calcination additives ammonium sulfate and ammonium bisulfate decomposing at appropriate temperatures to release highly acidic H₂S₂O₇, which reacts with weathered inert impurities adsorbed on the quartz surface or deeply embedded in the quartz lattice, as well as some gangue minerals not removed by reverse flotation or the first acid leaching, to generate soluble sulfates. Second acid leaching dissolves and removes the sulfates generated during additive calcination, and also removes some impurities originally encapsulated by inert impurities. Because the first and second acid leachings target different purposes, the mixed acid formulations used in the first (composed of hydrofluoric acid, oxalic acid, hydrochloric acid, and nitric acid) and the second (composed of hydrofluoric acid and hydrochloric acid) are also different. The second acid leaching uses fewer types of acids and contains very few impurities. Therefore, the second acid leaching filtrate can be recycled back to the first acid leaching process after dilution and / or the addition of new acids. The additive roasting process uses a wet mixing method with second quartz particles (10%–15% moisture content) that have not been dried after the first acid leaching and the additives. This results in good mixing and helps improve the reaction efficiency during the roasting stage.

[0031] Specifically, the method for preparing high-purity quartz by deep calcination of additives in this exemplary embodiment may include the following steps:

[0032] S1. The raw quartz ore is crushed, ground, and screened to obtain coarse powdered quartz particles.

[0033] S2. The coarse quartz powder particles are subjected to reverse flotation to obtain the first quartz particles.

[0034] S3. The first quartz particle is subjected to a first acid leaching to obtain the second quartz particle.

[0035] S4. After the second quartz particles are mixed evenly with the calcination aid, they are calcined to obtain the third quartz particles.

[0036] S5. The third quartz particles are subjected to a second acid leaching-water washing-drying process to obtain high-purity quartz.

[0037] In this exemplary embodiment, in step S1, the quartz ore mainly contains quartz, and may contain small amounts of gangue minerals such as magnetite, talc, mica, and feldspar. The mesh size of the coarse quartz powder can be -200 to +500 mesh, for example, 250 mesh, 300 mesh, 350 mesh, etc. If the quartz ore particles are too large, it will lead to incomplete dissociation of quartz monomers, resulting in a decrease in subsequent flotation effect, insufficient roasting reaction of subsequent additives, and a decrease in the purity of the final product; if the particles are too fine, it will cause an increase in the loss of quartz powder during acid leaching and a decrease in yield.

[0038] In this exemplary embodiment, in step S1, the crushing can be performed using one or more of the following: toothed roll crusher, double roll crusher, jaw crusher, gyratory crusher, and cone crusher.

[0039] In this exemplary embodiment, in step S2, reverse flotation may include: using industrial water as the flotation water, adjusting coarse quartz powder particles into a slurry with a slurry concentration of 20%–50%, such as 20%, 30%, or 40%. Here, too low a slurry concentration leads to a low concentrate recovery rate; too high a slurry concentration deteriorates the working conditions of the flotation machine, reducing the flotation effect. Hydrofluoric acid is used as a pH adjuster, with the flotation slurry pH being 1.0–2.5, such as 1.0, 1.5, or 2.5. Here, too low a pH consumes more hydrofluoric acid, and during reverse flotation, insoluble impurities such as aluminum fluoride and calcium fluoride are generated, affecting quartz purity; too high a pH causes the quartz in the slurry system to exhibit a negative potential, resulting in large-scale adsorption by the collector, significantly reducing concentrate yield and grade. A cationic amine collector is used for reverse flotation treatment to remove impurities. The concentrate is collected and washed with water until the pH of the filtrate is 7. After filtration, the first quartz particles are obtained, which ensures the removal of impurities such as collectors.

[0040] Furthermore, the collector may include one or more of dodecylamine, hexadecylamine, and octadecylamine, and the dosage may be 100–200 g / t, such as 100 g / t, 150 g / t, 200 g / t, etc. Here, excessively high dosage of collector will result in waste of reagents and increase the difficulty of wastewater treatment; excessively low dosage will make it difficult to completely float impurities in quartz, resulting in a decrease in the grade of quartz concentrate.

[0041] In this exemplary embodiment, step S3, the first acid leaching may include: mixing the first quartz particles with a first acid leaching solution, wherein the first acid leaching solution may include hydrofluoric acid, oxalic acid, hydrochloric acid, and nitric acid. The liquid-to-solid ratio used in the mixing may be 3–6 L / kg, for example, 3 L / kg, 4 L / kg, 5 L / kg, etc. Here, if the liquid-to-solid ratio is too low, the contact between the acid leaching solution and the powdered quartz will be insufficient, resulting in incomplete reaction; if the liquid-to-solid ratio is too high, the acid consumption will be high, resulting in high energy consumption.

[0042] Furthermore, in the first acid leaching, the molar concentration of hydrofluoric acid in the prepared acid leaching solution can be 2–8 mol / L, for example, 2 mol / L, 4 mol / L, 6 mol / L, etc.; the molar concentration of oxalic acid can be 0.2–0.8 mol / L, for example, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, etc.; the molar concentration of hydrochloric acid can be 0.5–5 mol / L, for example, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, etc.; and the molar concentration of nitric acid can be 0.2–1 mol / L, for example, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, etc. Here, hydrofluoric acid is used to corrode some defect sites on the quartz surface, exposing inclusions and other impurities. Too high a concentration leads to significant quartz loss and increases wastewater treatment difficulty, while too low a concentration results in incomplete corrosion of the quartz surface, failing to fully expose impurity sites and affecting purification efficiency. Oxalic acid is used to dissolve iron impurities in the quartz. Too high a concentration leads to acid waste and increased wastewater treatment difficulty, while too low a concentration results in incomplete impurity dissolution. Hydrochloric acid is used to react with other impurities in the quartz to form soluble chloride salts. Too high a concentration increases costs and further complicates subsequent wastewater treatment, while too low a concentration results in incomplete impurity dissolution. Nitric acid is used to increase the acid system abundance and dissolve small amounts of impurities insoluble in hydrochloric acid. Too high a concentration increases costs and wastewater treatment difficulty, while too low a concentration results in incomplete impurity dissolution and may lead to the formation of insoluble fluoride salts.

[0043] Furthermore, the temperature of the first acid leaching can be between 50℃ and 90℃, for example, 50℃, 60℃, 70℃, etc. Here, too low a temperature will lead to incomplete reaction, and too high a temperature will lead to increased energy consumption. The duration of the first acid leaching can be between 2 hours and 4 hours, for example, 2 hours, 3 hours, 4 hours, etc. Here, too short an acid leaching time will lead to incomplete reaction, and too long an acid leaching time will increase energy consumption.

[0044] In this exemplary embodiment, in step S3, after the first acid leaching reaction is completed, the acid leaching product can be filtered and washed until the pH of the filtrate is 7. After filtration (without drying), the second quartz particles can be obtained, which ensures the removal of soluble impurity ions and acid solution.

[0045] Furthermore, the moisture content of the second quartz particles can be 10% to 15%, such as 10%, 12%, 15%, etc. Here, too low a moisture content will lead to uneven mixing with the additives in the later stage, while too high a moisture content will lead to increased energy consumption during wet mixing.

[0046] In this exemplary embodiment, in step S4, the calcination aid may include one or both of ammonium sulfate and ammonium bisulfate. The calcination aid and the second quartz particles may be mixed uniformly at a mass ratio of 0.1 to 0.3, for example, 0.1, 0.2, 0.3, etc. Here, a mass ratio that is too low will lead to incomplete reaction and reduced purification effect; a mass ratio that is too high will lead to a large consumption of calcination aid and increased cost.

[0047] Furthermore, the calcination temperature can be 450–550℃, such as 450℃, 500℃, 550℃, etc. Here, if the calcination temperature is too low, the calcination aid will not decompose into strong acidic substances to react with impurities; if the calcination temperature is too high, the strong acidic substances decomposed by the calcination aid will continue to decompose into other substances, and some metal sulfates will also decompose into insoluble substances, reducing the purification effect. The calcination time can be 60–120 minutes, such as 60 minutes, 70 minutes, 80 minutes, etc. Here, if the calcination time is too short, the reaction will not be complete; if the calcination time is too long, energy consumption will be too high.

[0048] Furthermore, after the second quartz particles and reaction aids are mixed evenly, they can be placed in a high-temperature roasting furnace equipped with a gas collection device for roasting to obtain the third quartz particles. Here, the high-temperature roasting furnace equipped with the gas collection device has a gas collection device connected to the exhaust end of the high-temperature roasting furnace.

[0049] In this exemplary embodiment, in step S4, the calcination reaction product mainly contains quartz, as well as one or more soluble sulfates of aluminum sulfate, magnesium sulfate, calcium sulfate, and ferric sulfate formed in the reaction.

[0050] In this exemplary embodiment, in step S5, the second acid leaching may include: mixing the third quartz particles with the second acid solution, wherein the second acid leaching solution may include hydrofluoric acid and hydrochloric acid. The liquid-to-solid ratio used to mix the third quartz particles with the second acid solution is 6 to 14 L / kg, for example, 6 L / kg, 7 L / kg, 8 L / kg, etc.

[0051] Furthermore, in the second acid leaching, the molar concentration of hydrofluoric acid in the prepared leaching solution can be 0.8–2 mol / L, for example, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, etc.; the molar concentration of hydrochloric acid can be 0.2–1 mol / L, for example, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, etc. Here, the purpose of hydrofluoric acid is to dissolve the active sites exposed on the surface of the quartz particles after the calcination of the additives. Too high a concentration will lead to extensive corrosion of the quartz, a decrease in yield, and an increase in the difficulty of wastewater treatment. Too low a concentration will lead to incomplete corrosion of surface defect sites and a reduction in purification effect. Hydrofluoric acid can react with impurities such as Al, Ca, and Na to form insoluble fluoride salts such as calcium fluoride, aluminum fluoride, and sodium fluoride. The purpose of hydrochloric acid is to dissolve insoluble fluoride salts. Too high a concentration will increase the difficulty of wastewater treatment, while too low a concentration will lead to incomplete dissolution of impurities and a reduction in purification effect.

[0052] Furthermore, the temperature for the second acid leaching can be between 50℃ and 90℃, for example, 50℃, 60℃, or 70℃. Here, too low a temperature will lead to incomplete reaction, while too high a temperature will increase energy consumption. The duration of the second acid leaching can be between 2 hours and 4 hours, for example, 2 hours, 3 hours, or 4 hours. Here, too short a leaching time will lead to incomplete reaction, while too long a leaching time will increase energy consumption.

[0053] In this exemplary embodiment, in step S5, after the second acid leaching reaction is completed, the acid leaching product can be filtered and washed until the pH of the filtrate is 7, and after drying, high-purity quartz can be obtained.

[0054] Furthermore, the second acid leaching filtrate can be diluted and / or have one or more of hydrofluoric acid, oxalic acid, hydrochloric acid, and nitric acid added, and then recycled back to the first acid leaching process in step S3 for reuse.

[0055] Exemplary Example 2

[0056] This exemplary embodiment provides a high-purity quartz.

[0057] High-purity quartz may include products prepared by the method for preparing high-purity quartz by deep impurity removal through calcination of additives as described in Exemplary Example 1 above.

[0058] In this exemplary embodiment, the SiO2 content in the high-purity quartz is above 99.9%, and can reach up to 99.995%. The particle size of the high-purity quartz particles can be from -200 mesh to +500 mesh. It should be noted that the symbols "+" and "-" represent "oversized" and "undersized," respectively.

[0059] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0060] Example 1

[0061] The quartz sample selected for this example experiment is powdered quartz. The XRD results of the raw quartz ore are as follows: Figure 2 As shown in Table 1, the raw quartz ore mainly contains quartz and talc. The XRF analysis results of the raw ore are shown in Table 1, revealing that the main impurity elements are Mg, Al, and Ca.

[0062] Table 1. Main chemical components of raw quartz ore

[0063] content(%) 97.85 1.12 0.21 0.10 0.05 0.02

[0064] Note: Elements not listed indicate that their content is less than 0.01%.

[0065] The preparation of the high-purity quartz of this example may include the following steps:

[0066] (1) The powdered quartz was crushed by a roller crusher and then screened to obtain coarse powdered quartz particles of 200-250 mesh.

[0067] (2) Reverse flotation of coarse quartz powder particles: The coarse quartz powder particles are adjusted into a slurry with industrial water and the slurry concentration is 20%; the pH of the slurry is adjusted to 1.0 with hydrofluoric acid; the collector is dodecylamine and the amount of collector is 100g / t; the reverse flotation concentrate is collected and washed with water until the pH of the filtrate is 7, and the first quartz particles are obtained after filtration.

[0068] (3) The first quartz particles were subjected to a first acid leaching: the acid leaching solution-solid ratio was 3 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 2 mol / L, the molar concentration of oxalic acid was 0.8 mol / L, the molar concentration of hydrochloric acid was 5 mol / L, and the molar concentration of nitric acid was 1 mol / L; the acid leaching temperature was 90℃; the acid leaching time was 3 h; after the acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7, and the second quartz particles with a water content of 10% were obtained.

[0069] (4) The second quartz particles and ammonium sulfate were mixed at a mass ratio of 0.1 and then placed in a high-temperature roasting furnace equipped with a gas collection device. The mixture was roasted at 450°C for 120 minutes to obtain the third quartz particles.

[0070] (5) The third quartz particles were subjected to a second acid leaching: the liquid-to-solid ratio of the acid leaching solution was 6 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 2 mol / L and the molar concentration of hydrochloric acid was 0.2 mol / L; the acid leaching temperature was 50℃; and the acid leaching time was 3 h.

[0071] (6) The second acid leaching product was filtered and washed until the pH of the filtrate was 7. The filtered product was dried at 105°C for 24 hours to obtain high-purity quartz. The acid leaching filtrate was recycled to the first acid leaching process after adding 0.8 mol / L oxalic acid, 4.8 mol / L hydrochloric acid and 1 mol / L nitric acid.

[0072] The high-purity quartz product in this example was tested using the silicon tetrafluoride volatilization method according to the national standard GB / T32649—2016, and the purity was 99.995%. The content of each element in the high-purity quartz product is shown in Table 2. The XRD results of the high-purity quartz in this example are as follows. Figure 3 As shown, the purified high-purity quartz product contains only the characteristic diffraction peaks of quartz, with no diffraction peaks of impurity minerals observed.

[0073] Table 2. Content of various impurity elements in high-purity quartz products (unit: μg / g)

[0074] 20.8 1.3 5.6 6.1 - 0.3 - - 0.54 1.3 0.1 0.7 1.5 0.6 1.9 40.74

[0075] Note: - indicates that it is below the ICP detection limit, i.e., ≤0.006μg / g.

[0076] Example 2

[0077] The quartz sample selected for this example experiment was powdered quartz. The XRF analysis results of the raw ore are shown in Table 3. It can be seen that the main impurity elements in the raw ore are Mg, Al, Ca, and Fe.

[0078] Table 3. Main chemical components of raw quartz ore

[0079] content(%) 97.59 0.35 1.80 0.05 0.02 0.02 0.01 0.16

[0080] Note: Elements not listed indicate that their content is less than 0.01%.

[0081] The preparation of the high-purity quartz of this example may include the following steps:

[0082] (1) The powdered quartz was crushed by a jaw crusher and then screened to obtain coarse powdered quartz particles of 300-350 mesh.

[0083] (2) Reverse flotation of coarse quartz powder particles: The coarse quartz powder particles are prepared into a slurry with industrial grade and the slurry concentration is 50%; the pH of the slurry is adjusted to 2.5 with hydrofluoric acid; the collector is hexadecylamine and the amount of collector is 200g / t; the reverse flotation concentrate is collected and washed with water until the pH of the filtrate is 7, and the first quartz particles are obtained after filtration.

[0084] (3) The first quartz particles were subjected to a first acid leaching: the acid leaching solution-solid ratio was 6 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 8 mol / L, the molar concentration of oxalic acid was 0.2 mol / L, the molar concentration of hydrochloric acid was 0.5 mol / L, and the molar concentration of nitric acid was 0.2 mol / L; the acid leaching temperature was 50℃; the acid leaching time was 2 h; after the acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7, and the second quartz particles with a water content of 12% were obtained.

[0085] (4) The second quartz particles and ammonium bisulfate were mixed at a mass ratio of 0.2 and then placed in a high-temperature roasting furnace equipped with a gas collection device. The mixture was roasted at 550°C for 60 minutes to obtain the third quartz particles.

[0086] (5) The third quartz particles were subjected to a second acid leaching: the liquid-to-solid ratio of the acid leaching solution was 14 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 0.8 mol / L and the molar concentration of hydrochloric acid was 1 mol / L; the acid leaching temperature was 90℃; and the acid leaching time was 4 h.

[0087] (6) The second acid leaching product was filtered and washed until the pH of the filtrate was 7. The filtered product was dried at 105°C for 24 hours to obtain high-purity quartz. The acid leaching filtrate was diluted by half and then 7.6 mol / L hydrofluoric acid, 0.2 mol / L oxalic acid and 0.2 mol / L nitric acid were added before recycling to the first acid leaching process for reuse.

[0088] The high-purity quartz product in this example was tested using the silicon tetrafluoride volatilization method according to the national standard GB / T32649—2016, and the purity was 99.992%. The content of each element in the high-purity quartz product is shown in Table 4.

[0089] Table 4. Content of various impurity elements in high-purity quartz products (unit: μg / g)

[0090] 45.5 0.8 13.6 16.3 - 0.5 - - 0.08 0.8 0.1 0.5 0.7 0.6 1.5 70.98

[0091] Note: - indicates that it is below the ICP detection limit, i.e., ≤0.006μg / g.

[0092] Example 3

[0093] The quartz sample selected for this example experiment was powdered quartz. The XRF analysis results of the raw ore are shown in Table 5, which shows that the main impurity elements in the raw ore are Mg, Al, and Ca.

[0094] Table 5. Main chemical components of raw quartz ore

[0095] content(%) 97.85 1.12 0.21 0.10 0.05 0.02

[0096] Note: Elements not listed indicate that their content is less than 0.01%.

[0097] The preparation of the high-purity quartz of this example may include the following steps:

[0098] (1) The powdered quartz was crushed by a gyratory crusher and then screened to obtain coarse powdered quartz particles of 400-500 mesh.

[0099] (2) Reverse flotation of coarse quartz powder particles: The coarse quartz powder particles are adjusted into a slurry with industrial water and the slurry concentration is 30%; the pH of the slurry is adjusted to 1.5 with hydrofluoric acid; the collector is octadecylamine and the amount of collector is 150g / t; the reverse flotation concentrate is collected and washed with water until the pH of the filtrate is 7, and the first quartz particles are obtained after filtration.

[0100] (3) The first quartz particles were subjected to a first acid leaching: the acid leaching solution-solid ratio was 5 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 4 mol / L, the molar concentration of oxalic acid was 0.6 mol / L, the molar concentration of hydrochloric acid was 3 mol / L, and the molar concentration of nitric acid was 0.5 mol / L; the acid leaching temperature was 70℃; the acid leaching time was 2 h; after the acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7, and the second quartz particles with a water content of 15% were obtained.

[0101] (4) The second quartz particles and ammonium sulfate were mixed in a mass ratio of 0.3 and then placed in a high-temperature roasting furnace equipped with a gas collection device. The mixture was roasted at 500°C for 90 minutes to obtain the third quartz particles.

[0102] (5) The third quartz particles were subjected to a second acid leaching: the liquid-to-solid ratio of the acid leaching solution was 10 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 1 mol / L and the molar concentration of hydrochloric acid was 0.6 mol / L; the acid leaching temperature was 70℃; and the acid leaching time was 4 h.

[0103] (6) The second acid leaching product was filtered and washed until the pH of the filtrate was 7. The filtered product was dried at 105℃ for 24 h to obtain high-purity quartz. The acid leaching filtrate was recycled to the first acid leaching process after adding 3 mol / L hydrofluoric acid, 0.6 mol / L oxalic acid, 2.4 mol / L hydrochloric acid and 0.5 mol / L nitric acid.

[0104] The high-purity quartz product in this example was tested using the silicon tetrafluoride volatilization method according to the national standard GB / T32649—2016, and the purity was 99.992%. The content of each element in the high-purity quartz product is shown in Table 6.

[0105] Table 6. Content of various impurity elements in high-purity quartz products (unit: μg / g)

[0106] 42.9 1.0 9.6 12.1 - 0.2 - - 0.24 0.9 0.6 0.9 0.9 0.6 1.5 70.54

[0107] Note: - indicates that it is below the ICP detection limit, i.e., ≤0.006μg / g.

[0108] Example 4

[0109] The quartz sample selected for this example experiment was powdered quartz, which mainly contained quartz and talc. The XRF analysis results of the raw quartz are shown in Table 7, which shows that the main impurity elements in the raw quartz are Mg, Al, and Ca.

[0110] Table 7. Main chemical components of raw quartz ore

[0111] content(%) 97.85 1.12 0.21 0.10 0.05 0.02

[0112] Note: Elements not listed indicate that their content is less than 0.01%.

[0113] The preparation of the high-purity quartz of this example may include the following steps:

[0114] (1) The powdered quartz was crushed by a cone crusher and then screened to obtain coarse powdered quartz particles of 200-250 mesh.

[0115] (2) Reverse flotation of coarse quartz powder particles: The coarse quartz powder particles are adjusted into a slurry with industrial water and the slurry concentration is 20%; the pH of the slurry is adjusted to 2.0 with hydrofluoric acid; the collector is dodecylamine and the amount of collector is 170g / t; the reverse flotation concentrate is collected and washed with water until the pH of the filtrate is 7, and the first quartz particles are obtained after filtration.

[0116] (3) The first quartz particles were subjected to a first acid leaching: the acid leaching solution-solid ratio was 5 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 3 mol / L, the molar concentration of oxalic acid was 0.8 mol / L, the molar concentration of hydrochloric acid was 5 mol / L, and the molar concentration of nitric acid was 0.8 mol / L; the acid leaching temperature was 90℃; the acid leaching time was 4 h; after the acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7, and the second quartz particles with a water content of 13% were obtained.

[0117] (4) The second quartz particles and ammonium bisulfate were mixed at a mass ratio of 0.2 and then placed in a high-temperature roasting furnace equipped with a gas collection device. The mixture was roasted at 550°C for 120 minutes to obtain the third quartz particles.

[0118] (5) The third quartz particles were subjected to a second acid leaching: the liquid-to-solid ratio of the acid leaching solution was 12 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 2 mol / L and the molar concentration of hydrochloric acid was 0.2 mol / L; the acid leaching temperature was 90℃; and the acid leaching time was 4 h.

[0119] (6) The second acid leaching product was filtered and washed until the pH of the filtrate was 7. The filtered product was dried at 105°C for 24 hours to obtain high-purity quartz. The acid leaching filtrate was recycled to the first acid leaching process after adding 1 mol / L hydrofluoric acid, 0.8 mol / L oxalic acid, 4.8 mol / L hydrochloric acid and 0.8 mol / L nitric acid.

[0120] The high-purity quartz product in this example was tested using the silicon tetrafluoride volatilization method according to the national standard GB / T32649—2016, and the purity was 99.992%. The content of each element in the high-purity quartz product is shown in Table 8.

[0121] Table 8. Content of various impurity elements in high-purity quartz products (unit: μg / g)

[0122] 43.8 1.7 12.4 12.5 - 0.3 - - 0.1 1.3 - 0.6 0.7 - 1.5 74.9

[0123] Note: - indicates that it is below the ICP detection limit, i.e., ≤0.006μg / g.

[0124] Example 5

[0125] The quartz sample selected for this example experiment was powdered quartz. The XRF analysis results of the raw ore are shown in Table 9. It can be seen that the main impurity elements in the raw ore are Mg, Al, Ca, and Fe.

[0126] Table 9. Main Chemical Components of Raw Quartz Ore

[0127] content(%) 97.59 0.35 1.80 0.05 0.02 0.02 0.01 0.16

[0128] Note: Elements not listed indicate that their content is less than 0.01%.

[0129] The preparation of the high-purity quartz of this example may include the following steps:

[0130] (1) The powdered quartz was crushed by a toothed roller crusher and then screened to obtain coarse powdered quartz particles of 400-450 mesh.

[0131] (2) Reverse flotation of coarse quartz powder particles: The coarse quartz powder particles are adjusted into a slurry with industrial water and the slurry concentration is 50%; the pH of the slurry is adjusted to 2.5 with hydrofluoric acid; the collector is octadecylamine and the amount of collector is 200g / t; the reverse flotation concentrate is collected and washed with water until the pH of the filtrate is 7, and the first quartz particles are obtained after filtration.

[0132] (3) The first quartz particles were subjected to a first acid leaching: the acid leaching solution-solid ratio was 5 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 8 mol / L, the molar concentration of oxalic acid was 0.8 mol / L, the molar concentration of hydrochloric acid was 3 mol / L, and the molar concentration of nitric acid was 0.8 mol / L; the acid leaching temperature was 70℃; the acid leaching time was 2 h; after the acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7, and the second quartz particles with a water content of 14% were obtained.

[0133] (4) The second quartz particles and ammonium sulfate were mixed at a mass ratio of 0.3 and then placed in a high-temperature roasting furnace equipped with a gas collection device. The mixture was roasted at 500°C for 120 minutes to obtain the third quartz particles.

[0134] (5) The third quartz particles were subjected to a second acid leaching: the liquid-to-solid ratio of the acid leaching solution was 14 L / kg; the molar concentration of hydrofluoric acid in the acid leaching solution was 1.5 mol / L and the molar concentration of hydrochloric acid was 1 mol / L; the acid leaching temperature was 90℃; and the acid leaching time was 2 h.

[0135] (6) The second acid leaching product was filtered and washed until the pH of the filtrate was 7. The filtered product was dried at 105°C for 24 hours to obtain high-purity quartz. The acid leaching filtrate was recycled to the first acid leaching process after adding 6.5 mol / L hydrofluoric acid, 0.8 mol / L oxalic acid, 2.0 mol / L hydrochloric acid and 0.8 mol / L nitric acid.

[0136] The high-purity quartz product in this example was tested using the silicon tetrafluoride volatilization method according to the national standard GB / T32649—2016, and the purity was 99.991%. The content of each element in the high-purity quartz product is shown in Table 10.

[0137] Table 10. Content of various impurity elements in high-purity quartz products (unit: μg / g)

[0138] 45.8 8.7 13.6 5.1 - 0.3 - - 1.5 1.8 0.1 1.4 1.5 1.2 3.9 84.9

[0139] Note: - indicates that it is below the ICP detection limit, i.e., ≤0.006μg / g.

[0140] In summary, the advantages proposed by this invention include at least one of the following:

[0141] (1) The calcination aid of the present invention can decompose into a super acidic substance at high temperature, which reacts with impurities such as inert alumina in quartz to generate soluble sulfate. Finally, the sulfate enters the acid leaching solution, thereby achieving the separation of inert impurities that are difficult to remove in conventional processes.

[0142] (2) The present invention mixes second quartz particles with a moisture content of 10% to 15% with calcination aids, which is more uniform than dry mixing and the calcination and impurity removal efficiency of the aids is high.

[0143] (3) The method for preparing high-purity quartz by deep calcination of additives proposed in this invention can adopt an acid recycling process. The second acid leaching filtrate can be recycled to the first acid leaching process section for reuse after dilution and / or addition of acid, which greatly reduces the amount of acid consumed and acidic wastewater, and has a beneficial effect on energy saving and environmental protection.

[0144] (4) The method for preparing high-purity quartz by deep calcination of additives proposed in this invention uses ammonium sulfate or ammonium bisulfate as calcination additives. The generated ammonia gas can be recovered and treated to obtain ammonia water, which reduces the environmental impact of the process and improves the sustainability of the process.

[0145] Although a method for preparing high-purity quartz by deep impurity removal of additives and high-purity quartz have been described above in conjunction with exemplary embodiments, those skilled in the art should understand that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for preparing high-purity quartz by deep impurity removal through calcination of additives, characterized in that, The method includes: The first quartz particles were obtained by pretreatment of the raw quartz powder. The first quartz particle was subjected to a first acid leaching to obtain the second quartz particle; The second quartz particles were mixed evenly with the calcination aid and then calcined to obtain the third quartz particles. The third quartz particles were subjected to a second acid leaching, followed by filtration, water washing and drying to obtain high-purity quartz. The first acid leaching includes: The first quartz particles and the first acid leaching solution are mixed at a liquid-to-solid ratio of 3–6 L / kg. The first acid leaching solution contains 2–8 mol / L hydrofluoric acid, 0.2–0.8 mol / L oxalic acid, 0.5–5 mol / L hydrochloric acid, and 0.2–1 mol / L nitric acid. The temperature for the first acid leaching is 50–90℃; the time for the first acid leaching is 2–4 hours. After the first acid leaching reaction was completed, the acid leaching product was filtered and washed until the pH of the filtrate was 7. The second quartz particles were obtained after filtration. The moisture content of the second quartz grain is 10%–15%; The second acid leaching includes: The third quartz particles were mixed with the second acid leaching solution at a liquid-to-solid ratio of 6–14 L / kg; the molar concentration of hydrofluoric acid in the second acid leaching solution was 0.8–2 mol / L, and the molar concentration of hydrochloric acid was 0.2–1 mol / L. The temperature for the second acid leaching is 50–90℃; the time for the second acid leaching is 2–4 hours. After the second acid leaching reaction, the solution is filtered and washed until the pH of the filtrate is 7, and then dried to obtain high-purity quartz. The calcination aid includes one or both of ammonium sulfate and ammonium bisulfate; the calcination aid and the second quartz particles are mixed evenly at a mass ratio of 0.1 to 0.

3.

2. The method for preparing high-purity quartz by deep calcination of additives according to claim 1, characterized in that, The roasting temperature is 450–550°C; the roasting time is 60–120 min.

3. The method for preparing high-purity quartz by deep calcination of additives according to claim 1, characterized in that, The preprocessing includes: The raw quartz powder is crushed, ground, and screened to obtain coarse quartz powder particles of -200 mesh to +500 mesh. The coarse quartz powder particles were subjected to reverse flotation to obtain the first quartz particles; The crushing process employs one or more of the following: toothed roll crusher, double roll crusher, jaw crusher, gyratory crusher, and cone crusher.

4. The method for preparing high-purity quartz by deep calcination of additives according to claim 3, characterized in that, The reverse flotation includes: The coarse quartz powder particles are adjusted into a slurry with a concentration of 20-50%; Adjust the pH of the pulp to 1.0–2.5; Add cationic amine collectors and perform reverse flotation to remove some impurity minerals; The reverse flotation concentrate was collected and washed with water until the pH of the filtrate was 7. After filtration, the first quartz particles were obtained.

5. The method for preparing high-purity quartz by deep calcination of additives according to claim 4, characterized in that, The reverse flotation process uses industrial water to prepare a slurry from coarse quartz powder; the reverse flotation process uses hydrofluoric acid to adjust the pH of the slurry; the cationic amine collector includes one or more of dodecylamine, hexadecylamine, and octadecylamine, and is used at a dosage of 100-200 g / t.

6. The method for preparing high-purity quartz by deep calcination of additives according to claim 1, characterized in that, The minerals contained in the powdered quartz ore include quartz, as well as one or more of magnetite, talc, mica and feldspar.

7. The method for preparing high-purity quartz by deep calcination of additives according to claim 1, characterized in that, The third quartz particle includes quartz, and one or more soluble sulfates selected from aluminum sulfate, magnesium sulfate, calcium sulfate and ferric sulfate formed by the reaction.

8. A high-purity quartz, characterized in that, The high-purity quartz is prepared by the method of deep impurity removal by calcination with additives as described in any one of claims 1 to 7. The high-purity quartz has a SiO2 content of 99.9% to 99.995% and a particle size of -200 mesh to +500 mesh.

Images