A process for preparing high-purity quartz by chlorination separation

Abstract

This invention discloses a process for preparing high-purity quartz using a chlorination separation method, comprising the following steps: S1, crushing, grinding, and classifying the raw quartz ore to obtain fine ore; S2, magnetically separating the fine ore to obtain a non-magnetic concentrate; S3, mixing the non-magnetic concentrate with water to form a slurry, and performing reverse flotation to obtain a flotation concentrate; S4, adding the flotation concentrate to a mixed acid solution for leaching to obtain an acid-leached concentrate; S5, mixing the acid-leached concentrate with high-purity graphite powder uniformly, and performing chlorination separation under a chlorine-containing atmosphere to obtain a chlorinated separation concentrate; S6, acid washing, water washing, and drying of the chlorinated separation concentrate to obtain high-purity quartz. This invention organically combines physical beneficiation (magnetic separation, reverse flotation) with deep chemical purification (pressure acid leaching, high-temperature chlorination), achieving stepwise and in-depth removal of impurities in different occurrence states in quartz ore, thereby significantly improving the purity of quartz.

Description

Technical Field

[0001] This invention belongs to the field of mineral purification technology, specifically relating to a process for preparing high-purity quartz by chlorination separation. Background Technology

[0002] Industrially, the purification process for high-purity quartz typically combines physical and chemical methods. Physical methods, such as color sorting, magnetic separation, and flotation, are mainly used for pretreatment, aiming to remove most of the associated impurities that exist as independent minerals in the raw quartz ore, such as feldspar and mica, reducing the impurity content to a low level. However, the occurrence state of impurities in quartz is extremely complex. In addition to independent mineral impurities, there are also a large number of inclusions (gas-liquid inclusions, mineral inclusions) existing on the surface of quartz particles, in internal fissures, and through isomorphous substitution of Si. 4+ Lattice impurities (mainly Al) that enter the quartz lattice 3 + Fe 3+ These deep-seated impurities, especially structurally stable lattice impurities, cannot be removed by conventional physical methods and are key to determining the upper limit of high-purity quartz quality.

[0003] To remove these stubborn impurities, deep chemical purification methods are necessary. Chemical methods mainly include acid treatment and high-temperature heat treatment. Acid treatment primarily targets inclusion impurities and some surface-attached impurities, but its effect on stable lattice impurities is limited. Heat treatment, especially chlorination, is considered an effective way to remove lattice impurities. Currently, high-temperature chlorination volatilization is a commonly used heat treatment technology in the industry. It is highly effective in removing alkali metals (K, Na) at temperatures around 1200℃, but its effect on other key impurities such as Al, Ti, Ca, and Mg is poor. The fundamental reason is that although these elements have a strong ability to combine with chlorine, they have an even stronger ability to combine with oxygen. This results in the formation free energy of their oxides being much lower than that of their chlorides, making them difficult to directly chlorinate under standard conditions.

[0004] Therefore, it is of great significance to develop a process technology that can efficiently remove various stubborn impurities such as Al, Fe, and Ti from quartz lattices under relatively mild conditions. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a process for preparing high-purity quartz by chlorination separation.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0008] S1. Crushing, grinding, and classifying the raw quartz ore to obtain fine ore;

[0009] S2. The fine ore is separated by magnetic separation to obtain a non-magnetic concentrate;

[0010] S3. Mix the non-magnetic concentrate with water to form a slurry, add it to the flotation machine, add the inhibitor, pH adjuster and composite collector in sequence, carry out reverse flotation treatment, scrape off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0011] S4. Add the flotation concentrate to the mixed acid solution, then add the composite additive, and carry out leaching treatment under heating and pressure to obtain acid leached concentrate.

[0012] S5. Mix the acid-leached concentrate with high-purity graphite powder evenly, and perform chlorination separation treatment under a chlorine-containing atmosphere to obtain chlorinated separation concentrate;

[0013] S6. The chloride-separated concentrate is acid-washed, water-washed, and dried to obtain high-purity quartz.

[0014] Preferably, the particle size of the fine mineral in step S1 is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0015] In this invention, the individual dissociation of impurity minerals is achieved through crushing, grinding, and classification, while avoiding excessive crushing of quartz. At the same time, the particle size and classification of fine minerals are limited, effectively controlling the generation of fine-grained slime. Excessive slime will deteriorate the flotation process, adsorb a large amount of reagents, cover the mineral surface, and affect the stability of foam, thereby reducing the separation efficiency and selectivity.

[0016] Preferably, the magnetic separation in step S2 adopts wet high-intensity magnetic separation with a magnetic field strength of 1.2-2.0T and a pulp concentration of 15%-25%.

[0017] In this invention, wet strong magnetic separation is used to efficiently remove iron-containing strongly magnetic and weakly magnetic minerals, thereby initially reducing the iron content in the product.

[0018] Preferably, the concentration of the slurry in step S3 is 25-35%, the inhibitor is water glass, the pH adjuster is sulfuric acid, and the pH value of the slurry is adjusted to 2.5-4.0; the dosage of the inhibitor is 500-1000g per ton of non-magnetic concentrate, and the dosage of the composite collector is 400-900g.

[0019] In this invention, the key step of separating silicate impurities (mainly feldspar and mica) with extremely similar physical properties to quartz through reverse flotation is the use of a highly specific composite collector. Under acidic conditions, the hydrophilicity of the quartz surface adsorbed by water glass is enhanced. The composite collector of this invention, with its imine nitrogen atoms and phenolic hydroxyl oxygen atoms, effectively targets the Al atoms on the surface of minerals such as feldspar and mica. 3+ Fe 3+ The active sites have the ability to capture impurities. Through the synergistic effect of chemical chelation and electrostatic attraction, they are strongly adsorbed onto the surface of impurity minerals, causing them to float hydrophobically, thereby removing impurities and improving the purity of quartz.

[0020] Preferably, the preparation method of the composite collector in step S3 is as follows:

[0021] Salicylic aldehyde was added to ethanol, followed by dodecylamine, and the mixture was refluxed. After the reaction was complete, a mixture was obtained. Then, copper chloride ethanol solution was added to the mixture and the mixture was stirred. After the reaction was complete, the mixture was distilled under reduced pressure to 1 / 2 to 2 / 3 of its original volume to obtain a concentrated solution. Then, methyl isobutyl methanol and Tween-80 were added to the concentrated solution and mixed thoroughly to obtain the final product.

[0022] Preferably, the mass ratio of salicylaldehyde, ethanol, dodecylamine, and copper chloride ethanol solution is 10-15:300-400:15-25:25-40, and the mass concentration of copper chloride ethanol solution is 20-30%; the reflux reaction temperature is 75-80℃ and the time is 2-3 hours, the stirring reaction temperature is 60-70℃ and the time is 1-2 hours; the mass ratio of concentrated solution, methyl isobutyl methanol, and Tween-80 is 100:20-30:5-10.

[0023] In this invention, a specific long-chain Schiff base molecule is generated by a reflux reaction of salicylaldehyde and dodecylamine. The oxygen atom of the phenolic hydroxyl group and the nitrogen atom of the imine group (-CH=N-) in the molecular structure expose the Al atoms in the crystal lattice of minerals such as feldspar and mica. 3+ Fe 3+ It possesses extremely strong spatial matching and electronic affinity, enabling it to adsorb onto these impurity minerals through chelation. Simultaneously, the long dodecyl carbon chain exhibits hydrophobicity, causing the impurities to float. Methyl isobutyl methanol is a highly efficient foaming agent, producing foams of appropriate size and brittleness, facilitating the transport and scraping of the mineralized foam. Tween-80, as a nonionic surfactant, plays a role in emulsification and dispersion, helping the oily collector complex form stable, tiny oil droplets in the aqueous phase, increasing its contact area and probability with mineral particles, and improving reagent utilization. Through the synergistic effect of the raw materials in the composite collector, the purity of quartz is further improved.

[0024] In this invention, a specific salicylaldehyde is introduced. Its phenolic hydroxyl structure acts as an effective metal ion complexing agent, which can capture and mask free iron ions dissolved in the slurry during grinding and other processes, preventing these harmful ions from activating the quartz surface and causing it to float incorrectly, thus purifying the flotation environment. In addition, the phenolic hydroxyl structure also endows the collector with a certain antioxidant capacity, protecting the stability of active groups such as dodecylamine during storage and use.

[0025] Preferably, the mixed acid solution in step S4 is prepared by mixing nitric acid with a mass concentration of 65%~68% and hydrofluoric acid with a mass concentration of 40%~49% in a volume ratio of 5-10:1. The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3-4. The amount of the composite additive added is 1-2% of the mass of the flotation concentrate. The leaching treatment temperature is 140-160℃, the pressure is 1-1.5MPa, and the time is 10-20h.

[0026] Preferably, the preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 15-25%, and then 15-25g of a fluoroboric acid aqueous solution with a mass concentration of 40-50% and 3-5g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution and stirred evenly.

[0027] In this invention, under high temperature of 140-160℃ and high pressure of 1-1.5MPa, the mixed acid solution (especially HF) micro-corrodes the surface and cracks of quartz, opening mass transfer channels. Combined with fatty alcohol polyoxyethylene ether as a highly efficient wetting agent, it reduces the solid-liquid interfacial tension, allowing the acid solution and additives to quickly penetrate into the micro-cracks and lattice defects inside the quartz particles. The fluoroboric acid added to the composite additive undergoes a complexation reaction with cerium ions, forming a fluorine-cerium complex that allows cerium ions to penetrate into the defects of the quartz lattice, providing an in-situ catalyst for the subsequent high-temperature chlorination reaction. Simultaneously, the fluoroboric acid slowly hydrolyzes at high temperature, continuously releasing HF and maintaining the system's long-term corrosion resistance.

[0028] Preferably, in step S5, the amount of high-purity graphite powder added is 3-5% of the mass of the acid leaching concentrate; the chlorine-containing atmosphere is a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 10%-30%; the reaction temperature for chlorination separation is 900-1000℃, and the time is 2-4h.

[0029] Unlike traditional high-temperature chlorination, this invention utilizes a copper-cerium bimetallic in-situ catalytic system formed by trace amounts of copper introduced in S3 and cerium introduced in S4. Under a reducing atmosphere created by high-purity graphite powder at 900-1000℃, this catalytic system significantly reduces the activation energy for breaking impurity bonds such as Si-O-Al in the quartz lattice, promoting the conversion of solid-phase impurity oxides into gaseous metal chlorides. At the same time, graphite powder acts as a reducing agent to capture lattice oxygen, further disrupting the impurity's state, thereby achieving deep removal of stubborn lattice impurities at a milder temperature than traditional processes.

[0030] Preferably, the acid washing in step S6 is performed by using 10% dilute hydrochloric acid and stirring at 70-85°C for 1.5-2.5 hours; the water washing is performed by using deionized water until the filtrate is neutral; and the drying is performed by drying at 105-120°C for 5-8 hours.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The process for preparing high-purity quartz by chlorination separation provided by the present invention organically combines physical beneficiation (magnetic separation, reverse flotation) with chemical deep purification (pressure acid leaching, high-temperature chlorination) to remove impurities in different occurrence states in quartz ore in a stepwise and in-depth manner. Among them, the S1-S3 stages mainly remove independent mineral impurities that are associated with incomplete dissociation or similar physical properties; the S4-S5 stages remove interstitial impurities (such as lattice aluminum and iron) and inclusion impurities that cannot be removed by conventional acid washing. This process significantly reduces the content of all elements in quartz sand, and can produce high-purity quartz sand that meets the application requirements of high-tech fields such as semiconductors and photovoltaics. Moreover, the process flow is continuous, and there is a chemical synergistic effect between each step, which not only improves the purification efficiency, but also effectively controls the final yield of quartz concentrate.

[0033] (2) The process for preparing high-purity quartz by chlorination separation provided by the present invention adds a composite collector prepared by a specific method during the reverse flotation process, which significantly improves the selectivity for removing aluminum and iron silicate impurities in the reverse flotation stage; the composite collector utilizes the Schiff base structure formed by the condensation of salicylaldehyde and dodecylamine, and the imine nitrogen atom and phenolic hydroxyl oxygen atom on its molecule can react with Al on the surface of minerals such as feldspar and mica. 3+ Fe 3+The active sites form stable chelates; simultaneously, the introduced copper ions, acting as complexing centers, further enhance the collector's adsorption strength and hydrophobic modification effect on the surface of impurity minerals. Combined with specific slurry concentrations (25-35%) and a weakly acidic environment (pH 2.5-4.0), this collector can efficiently remove feldspar impurities that are difficult to separate due to their extremely similar physical properties to quartz through foam. In addition, the unique phenolic hydroxyl structure in the composite collector can effectively complex free iron ions in the slurry, preventing them from activating quartz and causing accidental flotation, and endowing the agent with certain antioxidant stability, minimizing the impurity load in subsequent chemical treatment stages and creating favorable conditions for deep purification.

[0034] (3) The process for preparing high-purity quartz by chlorination separation provided by the present invention adds a composite additive with specific raw materials during the acid leaching process. The synergistic effect of the additive and the nitric acid-hydrofluoric acid system enables deep penetration into the microcracks and lattice defects inside the quartz particles. In the pressurized acid leaching step, the micro-corrosion effect of hydrofluoric acid on the quartz surface is used to open the mass transfer channel. The fatty alcohol polyoxyethylene ether is used as a highly efficient wetting agent to reduce the solid-liquid interfacial tension, so that the acid and additive can quickly penetrate into the microcracks and lattice defects inside the quartz particles. During this process, the cerium ions in the composite additive enter the quartz lattice defects or inclusions through the penetration channel. This not only helps the acid dissolve some deep impurities, but more importantly, the cerium ions can penetrate into the defects of the quartz lattice along these newly opened channels, providing an in-situ catalyst for the subsequent high-temperature chlorination reaction, thereby significantly improving the purity of the quartz.

[0035] (4) The process for preparing high-purity quartz by chlorination separation provided by the present invention, in the chlorination separation stage of S5, the trace copper ions remaining in the flotation step of S3 and the cerium ions introduced in the acid leaching step of S4 form a copper-cerium bimetallic catalytic system. Under the conditions of high-purity graphite powder as a reducing agent and chlorine atmosphere, the catalytic system effectively reduces the activation energy of breaking the chemical bonds of impurities such as Si-O-Fe and Si-O-Al in the quartz lattice, and promotes the conversion of stable lattice oxide impurities into low-boiling-point chlorides (such as AlCl3 and FeCl3) and volatilization. This in-situ catalytic chlorination technology enables the process to achieve lattice purification that usually requires higher temperatures under relatively mild conditions of 900-1000℃. The entire process chain is closely linked. The efficient impurity removal in step S3 reduces the acid consumption and processing pressure in S4. The synergistic effect of S3 and S4 makes the chlorination reaction in S5 more thorough and faster. Finally, a complete, coherent and efficient system is used to achieve a purification depth that is difficult to achieve by other single or simple combination processes. Attached Figure Description

[0036] Figure 1 This is an optical microscope image of the high-purity quartz prepared in Example 1 of the present invention;

[0037] Figure 2 This is an optical microscope image of the high-purity quartz prepared in Comparative Example 1 of this invention;

[0038] Figure 3 This is an optical microscope image of the high-purity quartz prepared in Comparative Example 2 of this invention;

[0039] Figure 4 This is an optical microscope image of the high-purity quartz prepared in Comparative Example 3 of this invention;

[0040] Figure 5 This is an optical microscope image of the high-purity quartz prepared in Comparative Example 4 of this invention. Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0043] In this invention, the main chemical components of the quartz ore were analyzed by ICP-MS, and the content of Al was about 2100 ppm, Fe was about 180 ppm, K was about 1200 ppm, Na was about 850 ppm, Ti was about 35 ppm, and the total impurity content was about 4500 ppm. X-ray diffraction phase analysis showed that the ore was mainly composed of quartz (>99%) and trace amounts of potassium feldspar, sodium feldspar, mica, and iron-bearing minerals.

[0044] Example 1

[0045] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0046] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0047] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.5T and a pulp concentration of 20% to obtain a non-magnetic concentrate.

[0048] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 30%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 800g and the amount of composite collector used is 700g per ton of non-magnetic concentrate. Adjust the pH to 3 and perform reverse flotation treatment. The stirring speed is 1800r / min, the flotation time is 10min, and the aeration rate is 1.8L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0049] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 65% nitric acid and 45% hydrofluoric acid in a volume ratio of 7:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3.5. Then, 1.5% of the flotation concentrate mass of the composite additive is added. The mixture is leached at 150℃ and 1.3MPa for 15 hours to obtain the acid-leached concentrate.

[0050] S5. Mix the acid leaching concentrate with 4% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 20%). The reaction temperature of chlorination separation is 950℃ and the time is 3h to obtain chlorinated separation concentrate.

[0051] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 80°C for 2 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 110°C for 7 hours to obtain high-purity quartz.

[0052] The preparation method of the composite collector in step S3 is as follows:

[0053] 130g of salicylaldehyde was added to 3500g of ethanol, followed by 200g of dodecylamine. The mixture was refluxed at 78℃ for 2.5h. After the reaction was completed, a mixture was obtained. Then, 350g of 25% copper chloride ethanol solution was added to the mixture, and the mixture was stirred at 65℃ for 1.5h. After the reaction was completed, the mixture was distilled under reduced pressure to 2 / 3 of its original volume to obtain a concentrated solution. Then, 500g of methyl isobutyl methanol and 150g of Tween-80 were added to 2000g of the concentrated solution and mixed thoroughly to obtain the final product.

[0054] The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 20%, and then 20g of fluoroboric acid aqueous solution with a mass concentration of 45% and 4g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution. The mixture is stirred at room temperature for 25min.

[0055] Example 2

[0056] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0057] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0058] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.2T and a pulp concentration of 15% to obtain a non-magnetic concentrate.

[0059] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 25%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 500g and the amount of composite collector used is 400g per ton of non-magnetic concentrate. Adjust the pH to 2.5 and perform reverse flotation treatment. The stirring speed is 1600r / min, the flotation time is 12min, and the aeration rate is 1.5L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0060] S4. Add the flotation concentrate to a mixed acid solution (prepared by mixing 65% nitric acid and 40% hydrofluoric acid in a volume ratio of 5:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3. Then add 1% of the composite additive by mass of the flotation concentrate. Leach the solution for 20 hours at a temperature of 140℃ and a pressure of 1MPa to obtain the acid-leached concentrate.

[0061] S5. Mix the acid-leached concentrate with 3% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 10%). The reaction temperature of chlorination separation is 1000℃ and the time is 2h to obtain chlorinated separation concentrate.

[0062] S6. The chloride-separated concentrate was washed with 10% dilute hydrochloric acid at 70°C for 2.5 hours with stirring. Then it was washed with deionized water until the filtrate was neutral. The filtrate was dried at 105°C for 8 hours to obtain high-purity quartz.

[0063] The preparation method of the composite collector in step S3 is as follows:

[0064] 100g of salicylaldehyde was added to 3000g of ethanol, followed by 150g of dodecylamine. The mixture was refluxed at 75°C for 3 hours. After the reaction was completed, a mixture was obtained. Then, 250g of 20% copper chloride ethanol solution was added to the mixture, and the mixture was stirred at 60°C for 2 hours. After the reaction was completed, the mixture was distilled under reduced pressure to 2 / 3 of its original volume to obtain a concentrated solution. Then, 400g of methyl isobutyl methanol and 100g of Tween-80 were added to 2000g of the concentrated solution and mixed thoroughly to obtain the final product.

[0065] The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 15%, and then 15g of a fluoroboric acid aqueous solution with a mass concentration of 50% and 3g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution. The mixture is stirred at room temperature for 20min.

[0066] Example 3

[0067] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0068] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0069] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 2.0T and a pulp concentration of 25% to obtain a non-magnetic concentrate.

[0070] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 35%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 1000g and the amount of composite collector used is 900g per ton of non-magnetic concentrate. Adjust the pH to 4 and perform reverse flotation treatment. The stirring speed is 2000r / min, the flotation time is 8min, and the aeration rate is 2L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0071] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 68% nitric acid and 49% hydrofluoric acid in a volume ratio of 10:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:4. Then, 2% of the mass of the flotation concentrate composite additive is added. The mixture is leached at 160℃ and 1.5MPa for 10 hours to obtain the acid-leached concentrate.

[0072] S5. Mix the acid leaching concentrate with 5% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, with chlorine content of 30% by volume). The reaction temperature for chlorination separation is 900℃ and the time is 4h to obtain chlorinated separation concentrate.

[0073] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 85°C for 1.5 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 120°C for 5 hours to obtain high-purity quartz.

[0074] The preparation method of the composite collector in step S3 is as follows:

[0075] 150g of salicylaldehyde was added to 4000g of ethanol, followed by 250g of dodecylamine. The mixture was refluxed at 78℃ for 2 hours. After the reaction was completed, a mixture was obtained. Then, 400g of 20% copper chloride ethanol solution was added to the mixture, and the mixture was stirred at 70℃ for 1 hour. After the reaction was completed, the mixture was distilled under reduced pressure to half of its original volume to obtain a concentrated solution. Then, 600g of methyl isobutyl methanol and 200g of Tween-80 were added to 2000g of the concentrated solution and mixed thoroughly to obtain the final product.

[0076] The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 25%, and then 25g of fluoroboric acid aqueous solution with a mass concentration of 40% and 5g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution. The mixture is stirred at room temperature for 30min.

[0077] Comparative Example 1

[0078] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0079] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0080] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.5T and a pulp concentration of 20% to obtain a non-magnetic concentrate.

[0081] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 30%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 800g and the amount of composite collector used is 700g per ton of non-magnetic concentrate. Adjust the pH to 3 and perform reverse flotation treatment. The stirring speed is 1800r / min, the flotation time is 10min, and the aeration rate is 1.8L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0082] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 65% nitric acid and 45% hydrofluoric acid in a volume ratio of 7:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3.5. Then, 1.5% of the flotation concentrate mass of the composite additive is added. The mixture is leached at 150℃ and 1.3MPa for 15 hours to obtain the acid-leached concentrate.

[0083] S5. Mix the acid leaching concentrate with 4% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 20%). The reaction temperature of chlorination separation is 950℃ and the time is 3h to obtain chlorinated separation concentrate.

[0084] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 80°C for 2 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 110°C for 7 hours to obtain high-purity quartz.

[0085] The preparation method of the composite collector in step S3 is as follows:

[0086] Add 200g of dodecylamine to 3500g of ethanol and stir until homogeneous. Then add 350g of 25% copper chloride ethanol solution to the mixture and stir at 65℃ for 1.5h. After the reaction is complete, distill under reduced pressure to 2 / 3 of the original volume to obtain a concentrated solution. Then add 500g of methyl isobutyl methanol and 150g of Tween-80 to 2000g of the concentrated solution and mix well to obtain the final product.

[0087] The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 20%, and then 20g of fluoroboric acid aqueous solution with a mass concentration of 45% and 4g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution. The mixture is stirred at room temperature for 25min.

[0088] Compared with Example 1, this comparative example did not add salicylaldehyde in the preparation of the composite collector.

[0089] Comparative Example 2

[0090] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0091] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0092] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.5T and a pulp concentration of 20% to obtain a non-magnetic concentrate.

[0093] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 30%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 800g and the amount of composite collector used is 700g per ton of non-magnetic concentrate. Adjust the pH to 3 and perform reverse flotation treatment. The stirring speed is 1800r / min, the flotation time is 10min, and the aeration rate is 1.8L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0094] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 65% nitric acid and 45% hydrofluoric acid in a volume ratio of 7:1). The ratio of flotation concentrate to mixed acid solution is 1:3.5. The flotation concentrate is leached for 15 hours at a temperature of 150℃ and a pressure of 1.3MPa to obtain acid-leached concentrate.

[0095] S5. Mix the acid leaching concentrate with 4% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 20%). The reaction temperature of chlorination separation is 950℃ and the time is 3h to obtain chlorinated separation concentrate.

[0096] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 80°C for 2 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 110°C for 7 hours to obtain high-purity quartz.

[0097] The preparation method of the composite collector in step S3 is as follows:

[0098] 130g of salicylaldehyde was added to 3500g of ethanol, followed by 200g of dodecylamine. The mixture was refluxed at 78℃ for 2.5h. After the reaction was completed, a mixture was obtained. Then, 350g of 25% copper chloride ethanol solution was added to the mixture, and the mixture was stirred at 65℃ for 1.5h. After the reaction was completed, the mixture was distilled under reduced pressure to 2 / 3 of its original volume to obtain a concentrated solution. Then, 500g of methyl isobutyl methanol and 150g of Tween-80 were added to 2000g of the concentrated solution and mixed thoroughly to obtain the final product.

[0099] Compared with Example 1, no composite additive was added in step S4 of this comparative example.

[0100] Comparative Example 3

[0101] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0102] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0103] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.5T and a pulp concentration of 20% to obtain a non-magnetic concentrate.

[0104] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 30%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 800g and the amount of composite collector used is 700g per ton of non-magnetic concentrate. Adjust the pH to 3 and perform reverse flotation treatment. The stirring speed is 1800r / min, the flotation time is 10min, and the aeration rate is 1.8L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0105] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 65% nitric acid and 45% hydrofluoric acid in a volume ratio of 7:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3.5. Then, 1.5% of the flotation concentrate mass of the composite additive is added. The mixture is leached at 150℃ and 1.3MPa for 15 hours to obtain the acid-leached concentrate.

[0106] S5. Mix the acid leaching concentrate with 4% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 20%). The reaction temperature of chlorination separation is 950℃ and the time is 3h to obtain chlorinated separation concentrate.

[0107] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 80°C for 2 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 110°C for 7 hours to obtain high-purity quartz.

[0108] The preparation method of the composite collector in step S3 is as follows:

[0109] 130g of n-heptanal was added to 3500g of ethanol, followed by 200g of dodecylamine. The mixture was refluxed at 78℃ for 2.5h. After the reaction was completed, a mixture was obtained. Then, 350g of 25% copper chloride ethanol solution was added to the mixture, and the mixture was stirred at 65℃ for 1.5h. After the reaction was completed, the mixture was distilled under reduced pressure to 2 / 3 of its original volume to obtain a concentrated solution. Then, 500g of methyl isobutyl methanol and 150g of Tween-80 were added to 2000g of the concentrated solution and mixed thoroughly to obtain the final product.

[0110] The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 20%, and then 20g of fluoroboric acid aqueous solution with a mass concentration of 45% and 4g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution. The mixture is stirred at room temperature for 25min.

[0111] Compared with Example 1, this comparative example replaces salicylaldehyde in the composite collector with n-heptanal.

[0112] Comparative Example 4

[0113] A process for preparing high-purity quartz by chlorination separation includes the following steps:

[0114] S1. The raw quartz ore is crushed, ground, and classified to obtain fine ore. The particle size of the fine ore is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

[0115] S2. The fine ore is separated by magnetic separation using wet high-intensity magnetic separation with a magnetic field strength of 1.5T and a pulp concentration of 20% to obtain a non-magnetic concentrate.

[0116] S3. Mix non-magnetic concentrate with water to prepare a slurry with a concentration of 30%, add it to a flotation machine, and add inhibitor, sulfuric acid with a mass concentration of 10%, and composite collector in sequence. The amount of inhibitor used is 800g and the amount of composite collector used is 700g per ton of non-magnetic concentrate. Adjust the pH to 3 and perform reverse flotation treatment. The stirring speed is 1800r / min, the flotation time is 10min, and the aeration rate is 1.8L / min. Skim off the foam, and the product at the bottom of the kettle is the flotation concentrate.

[0117] S4. The flotation concentrate is added to a mixed acid solution (prepared by mixing 65% nitric acid and 45% hydrofluoric acid in a volume ratio of 7:1). The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3.5. Then, 1.5% of the flotation concentrate mass of the composite additive is added. The mixture is leached at 150℃ and 1.3MPa for 15 hours to obtain the acid-leached concentrate.

[0118] S5. Mix the acid leaching concentrate with 4% (by weight) of high-purity graphite powder and perform chlorination separation treatment in a chlorine-containing atmosphere (a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 20%). The reaction temperature of chlorination separation is 950℃ and the time is 3h to obtain chlorinated separation concentrate.

[0119] S6. The chloride-separated concentrate is washed with 10% dilute hydrochloric acid at 80°C for 2 hours with stirring. Then it is washed with deionized water until the filtrate is neutral. It is then dried at 110°C for 7 hours to obtain high-purity quartz.

[0120] The preparation method of the composite collector in step S3 is as follows:

[0121] Add 200g of dodecylamine to 3500g of ethanol and stir until homogeneous. Then add 350g of 25% copper chloride ethanol solution to the mixture and stir at 65℃ for 1.5h. After the reaction is complete, distill under reduced pressure to 2 / 3 of the original volume to obtain a concentrated solution. Then add 500g of methyl isobutyl methanol and 150g of Tween-80 to 2000g of the concentrated solution and mix well to obtain the final product.

[0122] Compared with Example 1, this comparative example did not add salicylaldehyde in the preparation of the composite collector, and did not add composite additives in step S4.

[0123] The high-purity quartz prepared in Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in Table 1 below. The Al content was approximately 2100 ppm, the Fe content was approximately 180 ppm, the K content was approximately 1200 ppm, the Na content was approximately 850 ppm, the Ti content was approximately 35 ppm, and the total impurity content was approximately 4500 ppm.

[0124] Table 1. Chemical purity (%) and impurity content of the final product (unit: ppmw)

[0125]

[0126] As can be seen from Table 1 above, the process for preparing high-purity quartz by chlorination separation provided by this invention produces SiO2 with a purity consistently above 99.999% and a total impurity content controlled below 10 ppmw, reaching the 5N level semiconductor / photovoltaic material standard and showing good application prospects.

[0127] from Figure 1-5 As can be seen, the high-purity quartz prepared by this invention has less shadow, indicating that it has fewer internal impurities, while the comparative examples 1-4 have more particulate impurities and larger shadows, especially comparative example 4. Figure 5 The largest shaded area in its quartz particles indicates that it contains more impurities.

[0128] The above description is a further detailed explanation of the present invention in conjunction with specific implementation examples. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the protection scope of the present invention.

[0129] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for preparing high-purity quartz by chlorination separation, characterized in that, Includes the following steps: S1. Crushing, grinding, and classifying the raw quartz ore to obtain fine ore; S2. The fine ore is separated by magnetic separation to obtain a non-magnetic concentrate; S3. Mix non-magnetic concentrate with water to prepare a slurry, add inhibitor, pH adjuster and composite collector in sequence, and perform reverse flotation to obtain flotation concentrate; S4. Add the flotation concentrate to the mixed acid solution, then add the composite additive, and carry out leaching treatment under heating and pressure to obtain acid leached concentrate. S5. Mix the acid-leached concentrate with high-purity graphite powder evenly, and perform chlorination separation treatment under a chlorine-containing atmosphere to obtain chlorinated separation concentrate; S6. The chloride-separated concentrate is acid-washed, water-washed, and dried to obtain high-purity quartz. The preparation method of the composite collector in step S3 is as follows: Salicylic aldehyde was added to ethanol, followed by dodecylamine, and the mixture was refluxed. After the reaction was complete, a mixture was obtained. Then, copper chloride ethanol solution was added to the mixture and the mixture was stirred. After the reaction was complete, the mixture was distilled under reduced pressure to 1 / 2 to 2 / 3 of its original volume to obtain a concentrated solution. Then, methyl isobutyl methanol and Tween-80 were added to the concentrated solution and mixed thoroughly to obtain the final product. The preparation method of the composite additive in step S4 is as follows: Cerium nitrate is prepared into an aqueous solution with a mass concentration of 15-25%, and then 15-25g of a fluoroboric acid aqueous solution with a mass concentration of 40-50% and 3-5g of fatty alcohol polyoxyethylene ether are added to 100g of cerium nitrate solution and stirred evenly.

2. The process according to claim 1, characterized in that, The particle size of the fine minerals mentioned in step S1 is controlled to be ≤0.25mm, and the content of particles smaller than 200 mesh does not exceed 15%.

3. The process according to claim 1, characterized in that, The magnetic separation in step S2 uses wet high-intensity magnetic separation with a magnetic field strength of 1.2-2.0T and a pulp concentration of 15%-25%.

4. The process according to claim 1, characterized in that, In step S3, the concentration of the slurry is 25-35%, the inhibitor is water glass, the pH adjuster is sulfuric acid, and the pH value of the slurry is adjusted to 2.5-4.0; the dosage of the inhibitor is 500-1000g per ton of non-magnetic concentrate, and the dosage of the composite collector is 400-900g.

5. The process according to claim 1, characterized in that, The mass ratio of salicylaldehyde, ethanol, dodecylamine, and copper chloride ethanol solution is 10-15:300-400:15-25:25-40, and the mass concentration of the copper chloride ethanol solution is 20-30%. The reflux reaction temperature is 75-80℃ and the time is 2-3 hours. The stirring reaction temperature is 60-70℃ and the time is 1-2 hours. The mass ratio of the concentrated solution, methyl isobutyl methanol, and Tween-80 is 100:20-30:5-10.

6. The process according to claim 1, characterized in that, The mixed acid solution in step S4 is prepared by mixing nitric acid with a mass concentration of 65%~68% and hydrofluoric acid with a mass concentration of 40%~49% in a volume ratio of 5-10:

1. The feed-to-liquid ratio of the flotation concentrate to the mixed acid solution is 1:3-4. The amount of the composite additive added is 1-2% of the mass of the flotation concentrate. The leaching treatment temperature is 140-160℃, the pressure is 1-1.5MPa, and the time is 10-20h.

7. The process according to claim 1, characterized in that, In step S5, the amount of high-purity graphite powder added is 3-5% of the mass of the acid-leached concentrate; the chlorine-containing atmosphere is a mixture of chlorine and nitrogen, wherein the volume content of chlorine is 10%-30%; the reaction temperature for chlorination separation is 900-1000℃, and the time is 2-4h.

8. The process according to claim 1, characterized in that, The pickling in step S6 involves using 10% dilute hydrochloric acid and stirring at 70-85°C for 1.5-2.5 hours. The water washing involves using deionized water until the filtrate is neutral. The drying involves drying at 105-120°C for 5-8 hours.

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