A purification method for granite pegmatite-type quartz ore

Abstract

This invention provides a method for purifying granite pegmatite-type quartz ore, belonging to the field of high-purity quartz purification technology. The method includes the following steps: sequentially washing, preliminary calcining, reverse flotation, deep calcination, and acid leaching of quartz sand particles to obtain purified quartz sand. The preliminary calcination temperature is 500-700℃, and the holding time is 0-60 min (not zero). The deep calcination temperature is 900-1200℃, and the holding time is 1-5 h. This invention achieves efficient flotation separation of associated mica and deep exposure of inclusions by controlling the temperature and time of the two calcination steps, resulting in high impurity removal efficiency. Data from the examples show that the SiO2 purity of the obtained quartz sand product is as high as 99.9965%.

Description

Technical Field

[0001] This invention relates to the field of high-purity quartz purification technology, specifically to a purification method for granite pegmatite-type quartz ore. Background Technology

[0002] Currently, the mainstream raw materials used internationally for producing high-purity quartz include vein quartz and granite pegmatite. While high-quality veins of vein quartz exist, they are generally small in scale and unstable in nature. Although granite pegmatite contains many associated impurities and is more difficult to purify, its large-scale mineralization and stable output make it an ideal raw material for producing high-purity quartz. For granite pegmatite, a combination of physical sorting and deep chemical purification processes is widely used to gradually remove feldspar, mica, iron and titanium oxides, gas-liquid inclusions, and lattice impurities.

[0003] The related technology discloses a method for purifying and preparing high-purity quartz sand using granite pegmatite as raw material. The process involves calcination, water quenching, crushing, screening, flotation, and finally acid washing. Directly calcining and water quenching the granite pegmatite raw material is not conducive to the separation of associated impurities and causes external impurities to enter the interior of the quartz particles, resulting in low impurity removal efficiency. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a purification method for granite pegmatite-type quartz ore. This invention achieves efficient flotation separation of associated mica and deep exposure of inclusions in the pegmatite ore by controlling the temperature and time of a two-step calcination process, resulting in high impurity removal efficiency.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for purifying granite pegmatite-type quartz ore, comprising the following steps: Quartz sand particles are sequentially washed, pre-calcined, reverse flotation, deep calcined, and acid leached to obtain purified quartz sand. The initial calcination temperature is 500~700℃, and the holding time is 0~60min and not 0; The deep calcination temperature is 900~1200℃, and the holding time is 1~5h.

[0006] Preferably, the initial calcination temperature is 600°C.

[0007] Preferably, the temperature of the deep calcination is 1100°C.

[0008] Preferably, the collector for the reverse flotation includes dodecylamine and dodecyl dimethyl benzyl ammonium chloride, and the pH of the slurry during the reverse flotation is 2 to 4.

[0009] Preferably, an alkaline pH adjuster and a dispersant are also added during the scrubbing process.

[0010] Preferably, the alkaline pH adjuster includes one or more of sodium hydroxide, potassium hydroxide, and calcium oxide, and the dispersant includes anionic dispersants.

[0011] Preferably, the acid solution used for acid leaching includes hydrochloric acid and / or hydrofluoric acid, and the acid leaching process is further enhanced by an external field, which includes a temperature field, a pressure field, and a stirring field.

[0012] Preferably, the reverse flotation process further includes: sequentially water quenching and grinding the material obtained from the initial calcination, wherein the particle size of the particles obtained from the grinding is 0.106~0.5mm.

[0013] Preferably, the deep calcination process further includes water quenching.

[0014] Preferably, the particle size of the quartz sand is 3~5mm.

[0015] This invention provides a method for purifying granite pegmatite-type quartz ore, comprising the following steps: Quartz sand particles are sequentially washed, pre-calcined, reverse flotation, deep calcined, and acid leached to obtain purified quartz sand. The initial calcination temperature is 500~700℃, and the holding time is 0~60min and not 0; The deep calcination temperature is 900~1200℃, and the holding time is 1~5h.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a combined process of preliminary calcination (preliminary low-temperature short-time calcination) and deep calcination (secondary high-temperature long-time calcination). The preliminary low-temperature short-time calcination, while preserving the floatability of mica as much as possible, allows quartz to undergo its first phase transformation, promoting complete dissociation between quartz and mica. Because the mica does not undergo prolonged high-temperature calcination during the preliminary calcination, it still retains significant floatability and is easily separated from quartz by flotation. The secondary high-temperature long-time calcination further exposes the inclusions within the quartz sand in a more directional manner, enhancing the subsequent acid leaching and impurity removal effect, resulting in high impurity removal efficiency. Data from the embodiments show that the SiO2 purity of the quartz sand product obtained by this invention reaches as high as 99.9965%.

[0017] Furthermore, this invention employs external field-enhanced acid leaching to remove internal impurities from quartz. After secondary high-temperature long-term calcination and water quenching, the quartz sand particles generate a large number of microcracks that directly reach the inclusions. High pressure forces the acid solution into the inclusions, and high temperature increases the reaction rate between the acid and the impurities. Stirring prevents the quartz sand from clumping and increases the contact reaction area, further improving the impurity removal efficiency. Detailed Implementation

[0018] This invention provides a method for purifying granite pegmatite-type quartz ore, comprising the following steps: Quartz sand particles are sequentially washed, pre-calcined, reverse flotation, deep calcined, and acid leached to obtain purified quartz sand. The initial calcination temperature is 500~700℃, and the holding time is 0~60min and not 0; The deep calcination temperature is 900~1200℃, and the holding time is 1~5h.

[0019] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0020] The present invention preferably involves crushing the pegmatite ore to obtain the quartz sand particles.

[0021] In this invention, the particle size of the quartz sand particles is preferably 3-5 mm.

[0022] In this invention, jaw crushers and double roll crushers are preferably used for crushing, and the crushed material is preferably screened to obtain the quartz sand particles.

[0023] After obtaining the quartz sand particles, the present invention sequentially performs scrubbing, preliminary calcination, reverse flotation, deep calcination and acid leaching on the quartz sand particles to obtain purified quartz sand.

[0024] In this invention, the scrubbing is preferably carried out by preparing quartz sand particles into a slurry, adding an alkaline pH adjuster and a dispersant, and then scrubbing in a scrubbing machine. The purpose of the scrubbing is to remove fine mud impurities (such as clay minerals such as kaolinite and chlorite) that adhere to the surface of the ore during mining, transportation and crushing, as well as some common mica feldspar impurity minerals.

[0025] In this invention, the concentration of the slurry is preferably 70%, and the concentration of the slurry refers to the percentage of the mass of quartz sand particles to the total mass of the slurry.

[0026] In this invention, the alkaline pH adjuster preferably includes one or more of sodium hydroxide, potassium hydroxide, and calcium oxide. The amount of the alkaline pH adjuster is based on the mass of the slurry, preferably 0.1%. The purpose of the alkaline pH adjuster is to adjust the pH value of the slurry to >7, avoiding the isoelectric point of quartz and muscovite, so that the mineral surface is negatively charged. It can activate sodium hexametaphosphate to enhance its dispersion stability (sodium hexametaphosphate is easily hydrolyzed and ineffective under acidic conditions). The weak alkali can slightly dissolve the clay minerals attached to the surface of quartz, preventing quartz particles from agglomerating.

[0027] In this invention, the dispersant preferably includes an anionic dispersant, which preferably includes one or more of sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, and sodium silicate. The amount of the dispersant is based on the mass of the slurry, preferably 0.5%. The anionic dispersant can prevent agglomeration, increase the fluidity of the slurry, and facilitate the removal of fine clay mineral impurities such as chlorite and kaolinite adhering to the surface of the minerals.

[0028] In this invention, the scrubbing time is preferably 40 minutes, and the rotation speed of the agitator of the scrubbing machine is preferably 1500 r / min.

[0029] In this invention, after the scrubbing is completed, the obtained minerals are preferably washed and dried in sequence before the preliminary calcination is carried out.

[0030] In this invention, the obtained minerals are preferably washed thoroughly under running water until the water becomes clear, so as to completely remove the stripped fine mud and associated minerals; the drying is preferably carried out in an oven, the drying temperature is preferably 105°C, and the drying time is preferably 12 hours.

[0031] In this invention, the initial calcination temperature is 500~700℃, specifically 550, 600 or 650℃, and the holding time is 0~60min and not 0, specifically 10, 30, 40 or 50min. The initial calcination is preferably carried out in a muffle furnace.

[0032] In this invention, the preliminary calcination serves to: thermally activate the associated mica, expand the interlayer spacing of the mica, expose more hydroxyl groups, significantly improve the floatability of the mica, and promote the complete dissociation of quartz and mica. Because the mica has not undergone prolonged high-temperature calcination, it still possesses considerable floatability and is easily separated from quartz by flotation, creating optimal conditions for subsequent reverse flotation separation. When the temperature is 500~570℃, it has a thermal activation effect on the mica, removing interlayer water and improving its floatability. When the temperature reaches 573℃, the quartz... The initial phase transformation of mica reduces its hardness, thereby reducing subsequent grinding energy consumption and increasing the yield of qualified particle sizes. When the temperature exceeds 600℃, mica crystals begin to undergo dehydroxylation, their layered structure is destroyed, and their floatability begins to deteriorate. When the temperature exceeds 800℃, the high temperature causes the mica structure to collapse, completely losing its natural floatability. Therefore, the initial calcination temperature is selected at 500~700℃. This thermally activates the mica, improving its floatability and facilitating flotation separation, while simultaneously causing the initial phase transformation of quartz, reducing its hardness, decreasing grinding energy consumption, and increasing grinding efficiency.

[0033] The present invention preferably raises the temperature from 50°C to the initial calcination temperature at a heating rate of 10°C / min.

[0034] In this invention, after the initial calcination and before reverse flotation, it is preferable to further include water quenching and grinding in sequence.

[0035] In this invention, the water quenching preferably uses room temperature distilled water, and more preferably, the water temperature change before and after water quenching is controlled to be no more than 5°C.

[0036] In this invention, the grinding is preferably carried out in a rod mill, and the particle size of the particles obtained by grinding is preferably 0.106~0.5mm.

[0037] In this invention, the collector for reverse flotation preferably includes dodecylamine and dodecyl dimethyl benzyl ammonium chloride. The amount of collector used is based on the reverse flotation feed rate, with dodecylamine preferably used at 2000 g / t and dodecyl dimethyl benzyl ammonium chloride preferably used at 1000 g / t. During reverse flotation, 0.1 mol / L H₂SO₄ is preferably used as a modifier. The pH value of the slurry during reverse flotation is preferably 2-4, the rotation speed is preferably 1992 r / min, and the aeration pressure is preferably 0.2 m³ / min. 3 / h, the preferred time is 15min, the reverse flotation can remove mica.

[0038] In this invention, the temperature of the deep calcination is 900~1200℃, specifically 950, 1000, 1100 or 1500℃, and the holding time is 1~5h, specifically 2, 3 or 4h. The deep calcination is preferably carried out in a muffle furnace.

[0039] In this invention, the deep calcination process serves to: enable quartz to undergo a secondary phase transformation (870°C), further reducing its hardness and thermal conductivity, and creating micro-cracks that reach the inclusions, facilitating the bursting of fluid inclusions and the exposure of mineral inclusions. When the temperature exceeds 900°C, the structure of mica gradually collapses at high temperatures, its original regular layered structure disappears, its stability and acid resistance decrease, and it becomes easier to remove through subsequent acid leaching processes.

[0040] The present invention preferably raises the temperature from 50°C to the depth of calcination at a heating rate of 10°C / min.

[0041] In this invention, after the deep calcination is completed, the obtained mineral is preferably placed in room temperature distilled water for water quenching. More preferably, the water temperature change before and after water quenching is controlled to be no more than 5°C. Water quenching causes a greater temperature difference between the inside and outside of the quartz. By utilizing the difference in thermal expansion coefficients between the quartz and the inclusion impurities, microcracks are further increased, deepened and enlarged, thereby allowing the inclusions to be fully exposed. In this invention, quartz is a poor conductor of heat, with a thermal conductivity of only 1.8~5 W / (m·K) at 1100℃, which further decreases with increasing temperature, far lower than the 20~30 W / (m·K) of ceramics. Traditional water quenching processes use large-particle sand after crushing. During water quenching, the temperature difference only exists on the surface. Due to the limitation of heat conduction rate, the internal temperature of quartz particles remains relatively stable, and the inclusions cannot be fully exposed. This invention uses quartz sand with a particle size of 0.106~0.5 mm after grinding and flotation, and calcines it to 900~1200℃. This causes the quartz to undergo a secondary phase transformation (870℃), further reducing its hardness and thermal conductivity, without melting the quartz and causing a third phase transformation (1470℃).

[0042] In this invention, after the water quenching is completed, the acid leaching is preferably performed. The acid solution used for the acid leaching preferably includes hydrochloric acid and / or hydrofluoric acid. When the acid solution is hydrochloric acid or hydrofluoric acid, the mass fraction of the acid solution is preferably 5% to 25%, specifically 10%, 15% or 20%. When the acid solution is a mixed acid, the mass fraction of the acid solution is preferably 15wt%. The liquid-solid ratio of the acid leaching process is preferably 1:1 to 6:1, and the acid leaching time is preferably 4 hours.

[0043] In this invention, the acid leaching process is preferably enhanced by an external field, which includes a temperature field, a pressure field, and a stirring field. The temperature is preferably 80~200℃; the pressure is preferably 0~15MPa and not 0; and the stirring rate is preferably 0~800r / min and not 0. This invention uses external field-enhanced acid leaching to remove impurities inside quartz. After secondary high-temperature long-term calcination and water quenching, the quartz sand particles generate a large number of microcracks that directly reach the inclusions. The acid solution is forced into the inclusions by high pressure, the high temperature increases the reaction rate between the acid and the impurities, and the mechanical stirring prevents the quartz sand from agglomerating and increases the contact reaction area, further improving the impurity removal efficiency.

[0044] In this invention, after the acid leaching is completed, it is preferable to perform filtration and washing in sequence. The washing is to repeatedly rinse with deionized water until the pH value of the filtrate is 6-7, so as to obtain purified quartz sand.

[0045] In this invention, the purified quartz sand particles are mainly concerned with the degree of removal of Fe, Al and K impurities. It is preferred to control the total impurity content (including Fe, Al and K) to be less than 50 ppm. If this requirement is not met, it is preferred to adjust the acid leaching process parameters, including but not limited to increasing the acid volume, increasing the acid leaching temperature, increasing the stirring rate, extending the acid leaching time or increasing the acid leaching pressure.

[0046] The present invention preferably uses a detection method to determine the content of impurity elements in the quartz sand particles. The detection method preferably includes sequentially performing sample digestion treatment and inductively coupled plasma optical emission spectrometry (ICP-OES) detection. The sample digestion treatment preferably includes sequentially grinding, acid digestion and volume adjustment.

[0047] In this invention, the grinding is preferably performed by weighing a sample of quartz sand particles, grinding it in a mortar until there are no particles, and then transferring it to a clean and dried polytetrafluoroethylene conical flask for acid digestion.

[0048] In this invention, the acid digestion is preferably carried out by adding 65% MOS-grade hydrofluoric acid and 48% nitric acid by mass to the polytetrafluoroethylene conical flask, wherein the preferred ratio of the quartz sand particle sample, MOS-grade hydrofluoric acid and nitric acid is 1g:10mL:1mL.

[0049] In this invention, the acid digestion temperature is preferably 180°C, and the acid digestion time is preferably until the solid is completely dissolved, more preferably by heating.

[0050] In this invention, if the acid solution evaporates completely during digestion but the sample is not completely dissolved, it is preferable to add 65% hydrofluoric acid by mass until the solid is completely dissolved, continue heating to dryness, and after the sample is dry, add 48% nitric acid by mass. The volume ratio of the added nitric acid to the initial hydrofluoric acid is preferably 1 mL:20 mL. Then continue heating to dryness, stop heating, and add 48% nitric acid and ultrapure water by mass to the polytetrafluoroethylene conical flask to dissolve the residue. The volume ratio of the nitric acid to ultrapure water is preferably 1 mL:5 mL.

[0051] In this invention, the preferred method for volume adjustment is to transfer the solution obtained from the acid digestion to a volumetric flask, repeatedly rinse the conical flask with ultrapure water, transfer the washings into the volumetric flask, adjust the volume to the mark, shake well, and obtain the test solution.

[0052] In this invention, it is preferable to dilute the test solution by 10 times before sending it into an inductively coupled plasma atomic emission spectrometer for detection.

[0053] In this invention, the preferred parameters of the inductively coupled plasma atomic emission spectrometer are as follows: Plasma and RF: RF power 1200W, RF frequency 27.12MHz; Observation method: Axial argon flow rate (high purity Ar ≥ 99.999%), cooling gas (Plasma): 12~13L / min, auxiliary gas (Auxiliary): 0.5L / min, nebulizer (Nebulizer): 0.7~0.8L / min (pressure 0.2MPa), sample introduction system (HF resistant / high salt), nebulizer: concentric, PTFE, nebulization chamber: cyclonic, inert coating, torch: HF resistant quartz torch, center tube 2.0mm, peristaltic pump: 3~4 channels, pump speed 20~30rpm; Optics and acquisition: wavelength range 165~850nm, resolution ≤0.006nm, integration time: short wave 5~10s, long wave 3~5s, background correction: dynamic background fitting; Spectral lines analyzed: Al 396.152 nm, Fe 259.940 nm, Ti 334.941 nm, Ca 317.933 nm, Mg 285.213 nm, Na 589.592 nm, K 766.490 nm, Li 670.784 nm.

[0054] This invention addresses the challenges of preparing high-purity quartz sand from granite pegmatite, where a large amount of associated mica impurities exist. Traditional high-temperature calcination methods easily cause mica to lose its floatability, while low-temperature calcination fails to fully expose inclusions. This invention innovatively proposes a purification method for granite pegmatite-type quartz ore. This method efficiently removes the widespread and abundant mica impurities in granite pegmatite while simultaneously achieving directional and deep exposure and removal of inclusions, resulting in high impurity removal efficiency.

[0055] 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.

[0056] Example 1 Step 1: Crush and screen the granite pegmatite raw material using a jaw crusher and a double roll crusher to obtain quartz sand particles with a particle size of 3-5mm. Take 100g of the crushed and screened quartz sand particle sample and place it at the bottom of a quartz boat. Heat it in a muffle furnace from 50℃ to 600℃ at a heating rate of 10℃ / min and hold it at that temperature for 20min for preliminary calcination. After holding, quench it in a large amount of room temperature distilled water, keeping the water temperature rise before and after quenching no more than 5℃. Step 2: Grind the water-quenched product, then screen it. Take 0.106~0.5mm quartz sand for reverse flotation at a rotation speed of 1992 r / min for 15 min and an aeration pressure of 0.2m. 3 / h, dodecylamine and dodecyl dimethyl benzyl ammonium chloride are used in parallel as collectors, the amount of dodecylamine is 2000g / t, the amount of dodecyl dimethyl benzyl ammonium chloride is 1000g / t, the flotation pH is 3, and the associated mica is removed. Step 3: Take 50g of the sample after preliminary purification by reverse flotation and place it at the bottom of a quartz boat. Heat it in a muffle furnace from 50℃ to 1100℃ at a heating rate of 10℃ / min and hold it at that temperature for 180min for deep calcination. After holding, quench it in a large amount of room temperature distilled water, keeping the water temperature rise before and after quenching no more than 5℃. Step 4: Take 20g of the water-quenched and dried sample and put it into a high-temperature and high-pressure reactor. Add a mixture of hydrofluoric acid and hydrochloric acid with a liquid-to-solid ratio of 3:1. The concentrations of both hydrofluoric acid and hydrochloric acid are 20wt%. Set the reactor temperature to 180℃, the pressure to 3MPa, and the stirring speed to 300r / min for acid leaching for 4 hours to obtain the purified sample, i.e., quartz sand.

[0057] Example 2 The preparation steps are the same as in Example 1, except that the initial calcination temperature in step one is 500°C.

[0058] Example 3 The preparation steps are the same as in Example 1, except that the initial calcination temperature in step one is 700°C.

[0059] Example 4 The preparation steps are the same as in Example 1, except that the deep calcination temperature in step three is 900°C.

[0060] Example 5 The preparation steps are the same as in Example 1, except that the deep calcination temperature in step three is 1000°C.

[0061] Example 6 The preparation steps are the same as in Example 1, except that the deep calcination temperature in step three is 1200°C.

[0062] Comparative Example 1 The preparation steps are the same as in Example 1, except that step one is not performed.

[0063] Comparative Example 2 The preparation steps are the same as in Example 1, except that step three is not performed.

[0064] Comparative Example 3 The preparation steps are the same as in Example 1, except that the initial calcination temperature in step one is 1100°C and the deep calcination temperature in step three is 600°C.

[0065] Comparative Example 4 The preparation steps are the same as in Example 1, except that the initial calcination temperature in step one is 1100°C.

[0066] Comparative Example 5 The preparation steps are the same as in Example 1, except that the initial calcination temperature in step one is 600°C.

[0067] Test case The initial pegmatite had an excessively high impurity content, which was generally characterized by mass percentages: Al: 7.998%, Fe: 0.741%, K: 4.098%. Digest the purified samples from the examples and comparative examples: Weigh 3g of sample and grind it in a mortar until there are no particles. Weigh 2g of sample and pour it into a clean and dried PTFE conical flask. Turn on the hot plate and add 20mL of 65% MOS grade HF and 2mL of 48% HNO3. Digest at 180°C until the solid is completely dissolved. If the sample is not completely dissolved and the acid has evaporated, add a small amount of HF until the solid dissolves. After the sample in the conical flask has evaporated to dryness, add 1mL of 65% MOS grade HF. 48% HNO3 was added to a conical flask, which was gently shaken. The flask was placed on a hot plate and heated until it evaporated to dryness. The hot plate was then turned off. 1 mL of 48% HNO3 and 5 mL of ultrapure water were added to the conical flask until the solid dissolved. The solution was then diluted to volume. The dissolved solution was transferred to a 50 mL volumetric flask. The conical flask was rinsed repeatedly with ultrapure water. The washings were poured into the volumetric flask and diluted to the mark. The solution was diluted 10 times. The samples treated in Examples 1-6 and Comparative Examples 1-5 were detected using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0068] Specific parameters are as follows: Plasma and RF: RF power 1200W, RF frequency 27.12MHz; Observation method: Axial argon flow rate (high purity Ar ≥ 99.999%), cooling gas (Plasma): 12.5 L / min, auxiliary gas (Auxiliary): 0.5 L / min, nebulizer (Nebulizer): 0.8 L / min (pressure 0.2 MPa), sample introduction system (HF resistant / high salt), nebulizer: concentric, PTFE, nebulization chamber: cyclonic, inert coating, torch: HF resistant quartz torch, center tube 2.0 mm, peristaltic pump: 3~4 channels, pump speed 25 rpm; Optics and acquisition: wavelength range 165~850nm, resolution ≤0.006nm, integration time: 5s for short wavelength, 3s for long wavelength, background correction: dynamic background fitting; Spectral lines analyzed: Al 396.152 nm, Fe 259.940 nm, Ti 334.941 nm, Ca 317.933 nm, Mg 285.213 nm, Na 589.592 nm, K 766.490 nm, Li 670.784 nm.

[0069] Table 1. Content and purity of Fe, Al, and K in samples from Examples 1-6 and Comparative Examples 1-5

[0070] As shown in Table 1, Example 1 exhibited the best purification effect, with residual Fe, Al, and K content of 2.20 μg / g, 8.34 μg / g, and 4.32 μg / g, respectively, and a SiO2 purity as high as 99.99650%. Example 2 showed slightly higher impurity content than Example 1, with Fe, Al, and K content of 5.23 μg / g, 18.64 μg / g, and 5.73 μg / g, respectively, and a SiO2 purity of 99.99503%. This was due to the lower initial calcination temperature, but still accompanied by the opening of the mica interlayer spacing and the activation effect of exposed hydroxyl groups in the mica. Example 3 showed further increases in Fe, Al, and K content, reaching 6.33 μg / g, 24.16 μg / g, and 5.94 μg / g, respectively. The SiO2 purity was 99.99434% (g / g). This was because the initial calcination temperature was too high, resulting in excessive loss of mica hydroxyl groups and poorer floatability. The reverse flotation removal effect was slightly weaker, but deep calcination destroyed the mica structure, making it easier for acid to corrode, thus the purification effect was still considerable. In Example 4, the impurity content increased sharply, with Fe, Al, and K at 36.97 μg / g, 108.35 μg / g, and 11.01 μg / g, respectively, and the SiO2 purity dropped to 99.98244%. This was because the deep calcination temperature was too low, resulting in insufficient secondary phase transformation of quartz, incomplete inclusion bursting, and incomplete destruction of the mica structure, leading to a higher impurity content. In Example 5, the Fe, Al, and K content were 9.72 μg / g, 9.72 μg / g, and 9.72 μg / g, respectively. The concentrations of Fe, Al, and K in Example 6 were 8.88 μg / g, 45.48 μg / g, and 7.84 μg / g, respectively, with a SiO2 purity of 99.99174%, showing improvement over Example 4. However, the deep calcination temperature was still slightly low, and some high-temperature resistant inclusions were not fully exposed, resulting in incomplete collapse of the mica structure. In Example 6, the concentrations of Fe, Al, and K were 8.88 μg / g, 24.12 μg / g, and 8.95 μg / g, respectively, with a SiO2 purity of 99.99385%. However, the deep calcination temperature was too high, causing the mica and quartz to melt together. Impurities such as Fe, Al, and K in the mica migrated extensively into the quartz lattice, penetrating deep into the lattice, making them difficult to remove with acid leaching and resulting in poor purification. Comparative Example 1 omitted the initial calcination, resulting in a low mica removal rate and a large amount of mica... In Comparative Example 2, where deep calcination was omitted, impurities migrated, resulting in an excessive amount of impurities that could not be completely dissolved by the acid. In Comparative Example 2, where deep calcination was omitted, impurities were excessive, and many inclusions could not be broken or exposed, leading to incomplete dissolution by the acid. Omitting any step of calcination resulted in impurity residue. In Comparative Examples 3 and 4, the high temperature of the initial calcination directly destroyed the mica and caused it to partially sinter with the quartz, completely losing its floatability and making it impossible to remove by flotation. Impurities were excessive, and the acid could not completely dissolve them. In Comparative Example 5, the deep calcination temperature was too low, failing to destroy the mica structure. Many inclusions could not be broken or exposed, and the acid could not completely dissolve them. The impurity content in Comparative Examples 1 to 5 was significantly increased, and the purity of the quartz sand dropped below 99.98%.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle 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 purifying granite pegmatite-type quartz ore, characterized in that, Includes the following steps: Quartz sand particles are sequentially washed, pre-calcined, reverse flotation, deep calcined, and acid leached to obtain purified quartz sand. The initial calcination temperature is 500~700℃, and the holding time is 0~60min and not 0; The deep calcination temperature is 900~1200℃, and the holding time is 1~5h.

2. The purification method according to claim 1, characterized in that, The initial calcination temperature is 600℃.

3. The purification method according to claim 1, characterized in that, The temperature for deep calcination is 1100℃.

4. The purification method according to claim 1, characterized in that, The collector for the reverse flotation includes dodecylamine and dodecyl dimethyl benzyl ammonium chloride, and the pH of the slurry during the reverse flotation is 2 to 4.

5. The purification method according to claim 1, characterized in that, An alkaline pH adjuster and a dispersant are also added during the scrubbing process.

6. The purification method according to claim 5, characterized in that, The alkaline pH adjuster includes one or more of sodium hydroxide, potassium hydroxide, and calcium oxide, and the dispersant includes anionic dispersants.

7. The purification method according to claim 1, characterized in that, The acid solution used in the acid leaching includes hydrochloric acid and / or hydrofluoric acid, and the acid leaching process is further enhanced by an external field, which includes a temperature field, a pressure field, and a stirring field.

8. The purification method according to claim 1 or 2, characterized in that, The reverse flotation process further includes: sequentially water quenching and grinding the material obtained from the initial calcination, wherein the particle size of the particles obtained from the grinding is 0.106~0.5mm.

9. The purification method according to claim 1 or 3, characterized in that, The deep calcination process also includes water quenching.

10. The purification method according to claim 1, characterized in that, The particle size of the quartz sand is 3~5mm.

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