Method for efficiently and deeply removing quartz sand inclusions

Abstract

The present application relates to a kind of quartz sand inclusion impurity efficient depth removal method, belong to high-purity quartz high-efficiency preparation and non-metallic ore fine processing technical field.The method includes: quartz sand raw materials are mixed with insulating liquid, form slurry;The slurry is treated by N-stage high-voltage electric pulse, and intermediate quartz sand is obtained;N≥2, N is integer, and the pulse voltage of the N-1-stage high-voltage electric pulse treatment is greater than the pulse voltage of the N-stage high-voltage electric pulse treatment;The highest pulse voltage of the first-stage high-voltage electric pulse treatment is not higher than 500kV, and the lowest pulse voltage of the N-stage high-voltage electric pulse treatment is not lower than 50 kV;After the intermediate quartz sand is separated by solid-liquid, solid is taken and treated by acid immersion, and high-purity quartz sand is obtained.The present application innovatively combines the selective crushing of more than 2-stage high-voltage electric pulse and the mild chemical acid immersion technology, constructs efficient synergistic process system, and realizes the targeted depth removal of quartz sand internal inclusion impurity.

Description

Technical Field

[0001] This invention relates to a method for efficient and deep removal of inclusions in quartz sand, belonging to the technical field of high-purity quartz preparation and deep processing of non-metallic minerals. Background Technology

[0002] High-purity silica sand is an indispensable key material for industries such as semiconductors, photovoltaics, and optical communications, and is widely used in the manufacture of critical components such as quartz crucibles and optical fiber preforms. With the global energy transition and the rapid development of the digital economy, the market demand for high-purity silica sand, especially high-end products with excellent thermal stability and low impurity precipitation capabilities, is becoming increasingly urgent, and quality requirements are becoming more stringent. However, silica deposits that can directly meet the needs of such high-end applications are extremely rare, and global supply is highly concentrated. Therefore, it is crucial to continue developing efficient and universally applicable deep purification technologies for silica sand to ensure the security of the supply chain for my country's strategic emerging industries.

[0003] Removing inclusions is a significant challenge in the purification of quartz sand. Inclusions in quartz sand are primarily fluid inclusions, which are tiny gas-liquid bubbles trapped during the growth of the quartz crystal. These inclusions often contain dissolved impurity ions such as potassium, sodium, and iron. These inclusions are firmly locked inside the quartz, creating a physical difference from the quartz matrix. To overcome the challenge of inclusion removal, industry and academia have conducted extensive research, but all methods have significant limitations. High-temperature bursting is a commonly used method. Its principle is to use high-temperature calcination to vaporize the fluid inclusions inside the quartz, causing them to expand rapidly and break through the inclusion walls or create microcracks. To improve the bursting effect, high-temperature calcination is often combined with water quenching. This method is effective for some fluid inclusions, but it suffers from high energy consumption and high production costs. Furthermore, high-temperature heat treatment can easily lead to irreversible phase transitions in the quartz lattice or generate thermal stress cracks, impairing its key properties such as high-temperature stability. Direct strong acid leaching is another commonly mentioned method, which involves soaking quartz sand in a high-concentration mixed acid at high temperatures for an extended period, attempting to dissolve impurities through acid corrosion. However, this method primarily targets surface impurities and has extremely low efficiency in removing internal inclusions.

[0004] In recent years, high-voltage electric pulse crushing technology has attracted attention as an emerging material pretreatment method due to its unique selective crushing potential. Its basic principle is to utilize the differences in the physicochemical properties of different minerals, such as dielectric constant and conductivity, to generate shock waves locally under the action of high-voltage pulses, thereby achieving selective energy action at the target interface. Studies have found that this technology can induce microcracks inside quartz particles or cause localized rupture of inclusions. However, applying this technology alone to quartz sand purification still faces bottlenecks: on the one hand, high-voltage electric pulses can effectively open inclusions or create cracks between them and the quartz matrix, but relying solely on physical shock waves is insufficient to remove exposed impurities, especially those within inclusions; on the other hand, excessively increasing the pulse energy to achieve impurity removal can lead to over-crushing of the quartz particles themselves, reducing the yield of the target particle size.

[0005] Chinese patent (publication number CN120622497A) discloses a method and apparatus for removing gas-liquid inclusions from quartz sand. The method includes the following steps: S1. calcining the raw quartz ore; S2. subjecting the calcined quartz ore obtained in S1 to water quenching and high-voltage electric pulse treatment; S3. purifying the quartz ore obtained in S2 to obtain high-purity quartz sand. This method requires a pre-calcination treatment, which has the drawback of high energy consumption. Furthermore, the water quenching process after calcination carries the risk of secondary contamination of the material, and the process is lengthy. Summary of the Invention

[0006] To address the challenges of efficiently and selectively removing impurity inclusions within quartz particles during the preparation of high-purity quartz sand, and the high energy consumption and complex processes resulting from existing technologies that rely on high-energy-consuming roasting, this invention aims to provide a method for the efficient and deep removal of impurities from inclusions in quartz sand. This innovative method combines selective crushing with high-voltage electric pulses of level 2 or higher with gentle chemical acid leaching technology to construct an efficient and synergistic process system, achieving targeted and deep removal of impurities from inclusions within quartz sand.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for efficient and deep removal of inclusions in quartz sand, the method comprising:

[0008] (1) Mix the quartz sand raw material with the insulating liquid to form a slurry;

[0009] (2) The slurry is subjected to N-level high-voltage electric pulse treatment to obtain intermediate quartz sand; N≥2, N is an integer, and the pulse voltage of the N-1 level high-voltage electric pulse treatment is greater than the pulse voltage of the N-level high-voltage electric pulse treatment; the highest pulse voltage of the first level high-voltage electric pulse treatment is not higher than 500kV, and the lowest pulse voltage of the N-level high-voltage electric pulse treatment is not lower than 50kV.

[0010] (3) After solid-liquid separation, the solid material of the intermediate quartz sand is subjected to acid leaching treatment to obtain high-purity quartz sand.

[0011] This invention uses sorted quartz sand as raw material. Without high-temperature calcination, it employs N-stage high-voltage electric pulse treatment coupled with acid leaching for deep impurity removal, ultimately yielding high-purity quartz sand. The core of this invention lies in creating physical exposure channels for inclusions within the quartz particles using N-stage high-voltage electric pulses (with decreasing pulse voltage) in the presence of an insulating liquid. This allows subsequent low-concentration acid to penetrate along these channels and efficiently dissolve the impurities, thus solving the industry problem of difficult removal of internal impurities. This invention utilizes the property differences between the quartz matrix and the internal inclusions to guide the discharge energy to preferentially and selectively act on the interior of the inclusions or their interface with the quartz matrix. The shock wave generated in this process can rupture the target inclusions or create micro-cracks at the interface with the quartz matrix, while the quartz particle itself maintains its macroscopic structural integrity. This process completely avoids traditional high-energy-consuming calcination pretreatment, achieving precise dissociation through pure electrophysical methods. The subsequent acid leaching deep impurity removal treatment directly benefits from the exposure channels created in the previous steps. The acid can effectively penetrate into the opened package, directly contact and dissolve impurities such as metal oxides and salts, achieving a balance between deep purification and low consumption and low corrosion. The entire process chain embodies the systematic coupling of identifying differences, precise energy application, and deep purification, which not only solves the limitations of single technologies but also achieves a leap in overall efficiency.

[0012] Furthermore, the high-voltage pulse treatment of this invention employs an optimized mode of at least two stages in series with decreasing energy. Specifically, the treatment system consists of two or more stages of high-voltage pulse reaction units connected in series, with the pulse voltage amplitude applied in each subsequent stage being lower than that in the previous stage. This design is based on the state change of the material after the previous stage of treatment; that is, the first stage of high voltage ensures the initial breakdown and effective exposure of inclusions within quartz particles of various sizes in the raw material. After this stage of treatment, some qualified particles in the material have completed the exposure of inclusions. Subsequent stages use lower voltages to provide protective energy replenishment to the qualified particles exposed in the previous stage, acting only on residual inclusions or expanding the microcrack channels between inclusions and the quartz matrix, while avoiding over-crushing of the main quartz particles. This at least two-stage series, decreasing energy mode is one of the key designs for achieving efficient and economical industrial operation of this invention. Furthermore, the highest pulse voltage of the first stage of high-voltage pulse treatment is no higher than 500 kV, and the lowest pulse voltage of the Nth stage of high-voltage pulse treatment is no lower than 50 kV. The voltage range setting is directly related to the dielectric breakdown threshold of the quartz sand raw material. If the pulse voltage is below 50 kV, it is difficult to establish a strong electric field inside the particles that is strong enough to break down the inclusions. If the pulse voltage exceeds 500 kV, it will lead to excess energy, increasing unnecessary damage to the quartz body and equipment costs.

[0013] As a preferred embodiment, the quartz sand raw material is sorted quartz sand. The sorting described in this invention refers to the quartz sand raw material obtained by pre-treatment of the crushed and screened quartz sand using at least one of the following methods: electrostatic separation, magnetic separation, color sorting, and flotation. Electrostatic separation, magnetic separation, color sorting, and flotation are all conventional processes in quartz sand production.

[0014] As a preferred embodiment, the voltage difference between the pulse voltage of the Nth-stage high-voltage pulse treatment and the pulse voltage of the (N-1)th-stage high-voltage pulse treatment is 110~300 kV. This invention employs an N-stage series design with the preceding stage voltage being 110~300 kV higher than the following stage voltage, reflecting gradient processing and high efficiency / energy saving. The first stage uses a higher voltage to initially crush the raw material and expose inclusions. After the material is crushed in the first stage, the inclusions are partially exposed or weakened. The subsequent stage uses a lower voltage to refine the remaining inclusions or further expand interface cracks, while avoiding pulverization of the quartz sand. This achieves graded energy utilization, improves product yield, and reduces overall energy consumption.

[0015] As a preferred approach, the pulse width of each high-voltage pulse treatment stage is independently set to 100 ns to 2 μs, and the pulse repetition frequency is independently set to 20 Hz to 300 Hz. The pulse width is primarily chosen to balance energy efficiency and shock wave generation. A pulse width that is too short may fail to form a stable plasma channel, resulting in insufficient energy release; a pulse width that is too long will cause the discharge process to be dominated by thermal effects, weakening the mechanical fragmentation effect of the instantaneous shock wave. The selection of the pulse frequency balances processing throughput and energy controllability, ensuring sufficient pulse counts per unit time for effective processing, while avoiding excessively high frequencies that could lead to heat accumulation and equipment overload.

[0016] As a preferred option, N is 2 or 3; when N is 2, the pulse voltage of the first-stage high-voltage pulse processing is 280kV~500kV, and the pulse voltage of the second-stage high-voltage pulse processing is 150kV~250kV.

[0017] When N is 3, the pulse voltage of the first-stage high-voltage pulse treatment is 400kV~500kV, the pulse voltage of the second-stage high-voltage pulse treatment is 180kV~250kV, and the pulse voltage of the third-stage high-voltage pulse treatment is 50kV~120kV. Experiments have shown that under this optimized condition, higher purity quartz sand can be obtained.

[0018] As a preferred embodiment, the conductivity of the insulating liquid is below 30 μS / cm. During the high-voltage pulse treatment stage, quartz sand is mixed with an insulating liquid having a conductivity below 30 μS / cm to form a slurry. This low conductivity medium is crucial for ensuring the precise application of electric field energy to the inclusions within the quartz particles. Excessively high liquid conductivity would cause the pulse current to preferentially pass through the liquid medium, forming a bypass discharge, significantly weakening the concentration effect of the electric field at the quartz-inclusion interface, thus undermining the basis for selective fragmentation.

[0019] As a preferred embodiment, the insulating liquid is deionized water and / or high-purity ethanol with an ethanol content of not less than 99.5 wt%. Based on the dual considerations of the core mechanism of high-voltage pulse technology and process efficiency optimization, deionized water and / or high-purity ethanol can effectively insulate while possessing good fluidity and safety, and can avoid introducing other impurities, making it an ideal medium for industrial applications.

[0020] As a preferred embodiment, the mass ratio of the quartz sand raw material to the insulating liquid is 1:3~8. Under this preferred condition, efficient energy transfer and stable process operation can be achieved. An excessively high solid-liquid ratio will lead to increased slurry viscosity, uneven particle dispersion, affecting the uniformity of the electric field distribution, and may cause particle agglomeration, thus hindering the formation of discharge channels. An excessively low solid-liquid ratio, although beneficial for dispersion and cooling, will significantly reduce the single-processing volume, increase the medium circulation and processing costs, and may dilute the pulse energy density due to liquid overload.

[0021] As a preferred embodiment, the SiO2 content in the quartz sand raw material is ≥99.5%, and the particle size of the quartz sand raw material is 70μm~350μm. When the SiO2 content is lower than 99.5%, the raw material has a high impurity content, and may even contain residual associated mineral impurities that have not been removed. These impurities will consume a large amount of reagents, greatly increasing the ineffective consumption of acid media. A particle size of 70μm~350μm is the typical particle size range for ultra-high purity quartz sand. When the particle size is >350μm, the particles are coarse, the required breakdown voltage increases nonlinearly, and the electric field is difficult to act uniformly inside the particles; when the particle size is <70μm, the particles are fine and easily agglomerate in the slurry, affecting the formation of discharge channels.

[0022] As a preferred embodiment, the acid used in the acid leaching treatment is selected from at least one of hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, and oxalic acid. Based on the technical approach of this invention, N-level high-voltage electric pulse treatment has achieved the rupture of inclusions or the generation of microcracks with the quartz matrix, while acid leaching mainly achieves the removal of impurities from the inclusions.

[0023] As a preferred embodiment, the acid leaching treatment involves an acid concentration of 5-15 wt%, a temperature of 20°C-90°C, a solid-liquid mass ratio of 1:3-10, and a time of 0.5-4 hours. The N-stage high-voltage electric pulse treatment process has achieved inclusion rupture or the generation of microcracks at the interface with the quartz matrix. The acid leaching parameters are based on the impurity reaction and migration behavior in the synergistic process of high-voltage electric pulse-acid leaching. Therefore, the acid solution does not need to rely on high concentrations to forcibly corrode the quartz surface; an acid concentration of 5-15 wt% and a liquid-solid ratio of 1:3-10 are sufficient to efficiently penetrate into the inclusions and dissolve the target impurities, while significantly reducing acid consumption, wastewater treatment costs, and erosion of the quartz matrix. The determination of the temperature and time range aims to achieve a balance between reaction rate, energy consumption, and process controllability. This preferred embodiment reflects the transformation of the acid leaching process from traditional strong acid etching to precise cleaning, based on the microcracks achieved by the N-stage high-voltage electric pulse treatment. The concentration, temperature, and time of the acid leaching are all significantly optimized and reduced, achieving green, efficient, and deep impurity removal.

[0024] As a preferred embodiment, the acid leaching treatment is carried out at a temperature of 60-90°C for a time of 0.5-2 hours. At a lower temperature of 20-40°C, combined with an appropriate extension of the treatment time, most of the exposed ionic state and loosely bound impurities can be effectively removed, making it suitable for energy-sensitive applications. When more stable impurities need to be treated or higher efficiency is required, the temperature can be increased to 60-90°C, at which point the reaction rate is significantly accelerated and the treatment time can be shortened to 0.5-2 hours.

[0025] As a preferred embodiment, the high-purity quartz sand contains ≥99.99% SiO2.

[0026] As a preferred option, the quartz sand obtained by acid leaching is then washed and dried to obtain high-purity quartz sand.

[0027] As a preferred option, the high-purity quartz sand is used to produce quartz ingots, quartz tube devices, or to produce ultrapure quartz sand.

[0028] Compared with the prior art, the present invention has at least the following advantages:

[0029] (1) The high-purity quartz sand product obtained by the present invention has complete crystal shape and no significant structural damage. It can be used to produce quartz balls, quartz tubes and other devices, or to produce ultrapure quartz sand.

[0030] (2) The method of coupling N-level high voltage electric pulse with acid leaching proposed in this invention overcomes the limitations of single technology, greatly improves purification efficiency, and significantly reduces production energy consumption, acid consumption and environmental pollution, providing a new solution for the production of high-purity quartz sand.

[0031] (3) This invention pioneered a method for removing inclusion impurities by combining N-level high-voltage electric pulse treatment with mild acid leaching. Through a multi-level decreasing energy input design, it achieves a balance between selective rupture of inclusions and prevention of over-pulverization of particles. Coupled with acid leaching kinetic control, it reduces acid consumption and leaching temperature, thereby achieving green, efficient and deep removal of inclusion impurities.

[0032] (4) Compared with CN120622497A, this invention eliminates the high energy consumption and potential secondary pollution of the roasting pretreatment process, and achieves targeted removal of inclusions and impurities inside the quartz sand. It has technical advantages such as short process flow and low energy consumption. Furthermore, this invention innovatively adopts a multi-stage progressive electric pulse treatment process, which can achieve precise expansion and refinement of smaller inclusions or cracks generated in the early stage, greatly improving selectivity and energy utilization efficiency.

[0033] (5) The process logic of this invention is clear, and the core processes can be combined with existing mature equipment. Stability can be improved through intelligent control, and it has the potential for large-scale industrial application and significant economic benefits. Attached Figure Description

[0034] Figure 1 These are polarized microscope images of the quartz sand raw material and the high-purity quartz sand obtained from the purification process in Example 1. Figure 1 The image on the left is a polarizing microscope image of the quartz sand raw material. Figure 1 The image on the right is a polariscope image of the high-purity quartz sand obtained after purification. Figure 1 It can be seen that the purified high-purity quartz sand has low inclusion content and clear particles. Detailed Implementation

[0035] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0038] Example 1

[0039] Quartz sand with a SiO2 content of 99.7% and a particle size of 100μm~220μm was mixed with deionized water at a mass ratio of 1:5 to form a homogeneous slurry. The conductivity of the insulating liquid (deionized water) was 28μS / cm. The slurry was introduced into a high-voltage electric pulse reactor and treated with a two-stage series high-voltage electric pulse. The first stage pulse parameters were set as follows: voltage 350kV, pulse width 500ns, and frequency 150Hz; the second stage pulse parameters were set as follows: voltage 180kV, pulse width 800ns, and frequency 80Hz. The treated quartz sand was then acid-leached using a mixed solution of 8wt% hydrochloric acid and 1.5wt% hydrofluoric acid at 65℃ for 2 hours, with a solid-liquid mass ratio of 1:8. After treatment, the quartz sand was washed with deionized water and dried. The SiO2 content of the quartz sand product was measured to be 99.992%.

[0040] Example 2

[0041] Quartz sand with a SiO2 content of 99.5% and a particle size of 70μm~180μm was mixed with deionized water at a mass ratio of 1:3 to form a homogeneous slurry. The conductivity of the insulating liquid (deionized water) was 24μS / cm. The slurry was introduced into a high-voltage electric pulse reactor and treated with a three-stage series high-voltage electric pulse. The parameters of the first stage pulse were set as follows: voltage 400kV, pulse width 100ns, and frequency 100Hz; pulse width 250kV, pulse width 600ns, and frequency 100Hz; and pulse width 50kV, pulse width 1μs, and frequency 100Hz. The treated quartz sand was then acid-leached with 10wt% hydrochloric acid at 20℃ for 2.5h, with a solid-liquid mass ratio of 1:3. After treatment, the quartz sand was washed with deionized water and dried. The SiO2 content of the quartz sand product was measured to be 99.995%.

[0042] Example 3

[0043] Quartz sand with a SiO2 content of 99.8% and a particle size of 220μm~350μm was mixed with deionized water at a mass ratio of 1:8 to form a homogeneous slurry. The conductivity of the insulating liquid (deionized water) was 20μS / cm. The slurry was introduced into a high-voltage electric pulse reactor and treated with a two-stage series high-voltage electric pulse. The first stage pulse parameters were set as follows: voltage 280kV, pulse width 400ns, and frequency 80Hz; the second stage pulse parameters were set as follows: voltage 150kV, pulse width 2μs, and frequency 60Hz. The treated quartz sand was then acid-leached using a mixed solution of 12wt% hydrochloric acid and 3wt% oxalic acid at 50℃ for 3.5h, with a solid-liquid mass ratio of 1:10. After treatment, the quartz sand was washed with deionized water and dried. The SiO2 content of the quartz sand product was measured to be 99.992%.

[0044] Example 4

[0045] Quartz sand with a SiO2 content of 99.6% and a particle size of 80μm~180μm was mixed with deionized water at a mass ratio of 1:4 to form a homogeneous slurry. The conductivity of the insulating liquid (deionized water) was 26μS / cm. The slurry was introduced into a high-voltage electric pulse reactor and treated with a three-stage series high-voltage electric pulse. The parameters of the first stage pulse were set as follows: voltage 500kV, pulse width 200ns, frequency 200Hz; pulse width 220kV, pulse width 500ns, frequency 100Hz; and pulse width 110kV, pulse width 900ns, frequency 20Hz. The treated quartz sand was then acid-leached with a mixture of 12wt% hydrochloric acid and 3wt% hydrofluoric acid at 90℃ for 0.5h, with a solid-liquid mass ratio of 1:5. After treatment, the quartz sand was washed with deionized water and dried. The SiO2 content of the quartz sand product was measured to be 99.991%.

[0046] Example 5

[0047] Quartz sand with a SiO2 content of 99.7% and a particle size of 80μm~180μm was mixed with deionized water at a mass ratio of 1:5 to form a homogeneous slurry. The conductivity of the insulating liquid (deionized water) was 17μS / cm. The slurry was introduced into a high-voltage electric pulse reactor and treated with a two-stage series high-voltage electric pulse. The first stage pulse parameters were set as follows: voltage 320kV, pulse width 350ns, and frequency 300Hz; the second stage pulse parameters were set as follows: voltage 200kV, pulse width 70ns, and frequency 100Hz. The treated quartz sand was then acid-leached with 5wt% hydrofluoric acid at 40℃ for 4h, with a solid-liquid mass ratio of 1:4. After treatment, the quartz sand was washed with deionized water and dried. The SiO2 content of the quartz sand product was measured to be 99.994%.

[0048] Example 6

[0049] Compared to Example 1, the difference lies in that deionized water was replaced with an equal mass of high-purity ethanol (ethanol content of 99.8 wt%), the conductivity of which is 0.7 μS / cm. The SiO2 content in the treated quartz sand product was 99.991%.

[0050] Comparative Example 1

[0051] Compared to Example 5, the difference lies in that high-voltage pulse treatment is not used. Specifically, quartz sand with a SiO2 content of 99.7% and a particle size of 80μm~180μm is directly acid-leached using 5wt% hydrofluoric acid at 40°C for 4 hours, with a solid-liquid mass ratio of 1:4. After treatment, the quartz sand is washed with deionized water and dried, and the SiO2 content in the quartz sand product is measured to be 99.92%.

[0052] Comparative Example 2

[0053] Compared with Example 2, the only difference is that only one-stage high-voltage pulse treatment is used. The parameters of the first-stage high-voltage pulse are the same as those in Example 2: pulse voltage 400kV, pulse width 100ns, and frequency 100Hz. The SiO2 content in the quartz sand product after treatment is 99.98%.

[0054] Comparative Example 3

[0055] The only difference compared to Example 4 is that acid leaching was not used. The SiO2 content in the treated quartz sand product was 99.88%.

[0056] Comparative Example 4

[0057] The only difference from Example 5 is that the hydrofluoric acid concentration is 3 wt%.

[0058] The SiO2 content in the treated quartz sand product is 99.95%.

[0059] Comparative Example 5

[0060] Compared with Example 5, the only difference is that the parameters of the two high-voltage pulses are different. Specifically, the parameters of the first pulse are set to voltage 35kV, pulse width 350ns, and frequency 300Hz; the parameters of the second pulse are set to voltage 35kV, pulse width 70ns, and frequency 100Hz. The SiO2 content in the treated quartz sand product is 99.97%.

[0061] Comparative Example 6

[0062] Compared with Example 1, the difference is that: no insulating liquid was used, and the deionized water in Example 1 was replaced with an equal mass of tap water. The conductivity of tap water is 130 uS / cm, and the SiO2 content in the treated quartz sand product is 99.986%.

[0063] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for efficient and deep removal of inclusions in quartz sand, characterized in that: The method includes: (1) Mix the quartz sand raw material with the insulating liquid to form a slurry; (2) The slurry is subjected to N-level high-voltage electric pulse treatment to obtain intermediate quartz sand; N≥2, N is an integer, and the pulse voltage of the (N-1)th level high-voltage electric pulse treatment is greater than the pulse voltage of the Nth level high-voltage electric pulse treatment; the highest pulse voltage of the first level high-voltage electric pulse treatment is not higher than 500kV, and the lowest pulse voltage of the Nth level high-voltage electric pulse treatment is not lower than 50 kV; the voltage difference between the pulse voltage of the Nth level high-voltage electric pulse treatment and the pulse voltage of the (N-1)th level high-voltage electric pulse treatment is 110~300kV; (3) After solid-liquid separation, the solid material of the intermediate quartz sand is subjected to acid leaching treatment to obtain high-purity quartz sand.

2. The method for efficient and deep removal of inclusions in quartz sand according to claim 1, characterized in that: The conductivity of the insulating liquid is less than 30 μS / cm.

3. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: The pulse width of each high-voltage pulse processing stage is independently 100 ns to 2 μs, and the pulse repetition frequency is independently 20 Hz to 300 Hz.

4. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: N is 2 or 3; When N is 2, the pulse voltage of the first-stage high-voltage pulse treatment is 280kV~500kV, and the pulse voltage of the second-stage high-voltage pulse treatment is 150kV~250kV. When N is 3, the pulse voltage of the first-stage high-voltage pulse treatment is 400kV~500kV, the pulse voltage of the second-stage high-voltage pulse treatment is 180kV~250kV, and the pulse voltage of the third-stage high-voltage pulse treatment is 50kV~120kV.

5. The method for efficient and deep removal of inclusions in quartz sand according to claim 3, characterized in that: The insulating liquid is deionized water and / or high-purity ethanol with an ethanol content of not less than 99.5 wt%.

6. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: The mass ratio of the quartz sand raw material to the insulating liquid is 1:3~8.

7. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: The SiO2 content in the quartz sand raw material is ≥99.5%, and the particle size of the quartz sand raw material is 70μm~350μm.

8. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: The acid used in the acid leaching treatment is selected from at least one of hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, and oxalic acid; And / or, the acid concentration of the acid leaching treatment is 5~15wt%, the temperature is 20℃~90℃, the solid-liquid mass ratio is 1:3~10, and the time is 0.5h~4h.

9. A method for efficient and deep removal of inclusions in quartz sand according to claim 1 or 2, characterized in that: The high-purity quartz sand contains ≥99.99% SiO2.

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