A purification treatment process for producing high-purity quartz sand
The quartz sand purification process, which combines multi-stage crushing, grading, magnetic separation, scrubbing, and high-temperature treatment with circulating water washing, solves the problems of poor impurity removal and high energy consumption in existing technologies, and achieves efficient production of high-purity quartz sand.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI HEJU NEW MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-29
Smart Images
Figure CN122102137A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of quartz sand purification technology, specifically a purification process for the production of high-purity quartz sand. Background Technology
[0002] Quartz sand is quartz particles produced by crushing and processing quartz stone. Quartz stone is a non-metallic mineral, a hard, wear-resistant, and chemically stable silicate mineral. Quartz sand is milky white or colorless and translucent, with a Mohs hardness of 7.
[0003] Quartz sand is an important industrial mineral raw material, a non-hazardous chemical, and is widely used in glass, casting, ceramics and fireproof materials, ferrosilicon smelting, metallurgical flux, metallurgy, construction, chemical industry, plastics, rubber, abrasives, filter media, and other industries. In the production of quartz sand, purification is required to remove impurities. For example, invention patent CN118702113A discloses a quartz sand purification process and production line, including: S1, crushing quartz ore to form quartz blocks; S2, calcining the quartz blocks; S3, ... 3. Water quench the calcined quartz blocks; S4. Make quartz sand from the quartz blocks and perform magnetic separation on the quartz sand; S5. Perform flotation on the magnetically separated quartz sand; S6. Perform acid extraction on the flotation quartz sand; S7. Dry and cool the acid-extracted quartz sand; S8. Collect the quartz sand to obtain the finished product; This invention patent, after two crushing, two screening, two magnetic separation and other processes, is processed into a finished product. The purpose of setting multiple screening and magnetic separation is to reduce human intervention in the production process and produce high-purity quartz sand without human intervention.
[0004] However, the above-mentioned quartz sand purification process has the following drawbacks: 1) It relies on "calcination-water quenching-acid extraction", which has limited ability to remove difficult-to-remove lattice impurities (such as Al, B, Ti); 2) After drying and cooling, magnetic separation is performed again, but the iron removal at the front end may be incomplete or secondary pollution may be introduced in the process, affecting the purity of the processed sand; 3) Water quenching and acid washing rely on "pure water", resulting in high overall process cost. Therefore, a purification process for high-purity quartz sand production is proposed to solve the above problems. Summary of the Invention
[0005] (a) Technical problems to be solved
[0006] To address the shortcomings of existing technologies, this invention provides a purification process for the production of high-purity quartz sand, which has the advantages of good impurity removal effect and more energy-efficient overall process, solving the problems of limited impurity removal effect and high overall energy consumption.
[0007] (II) Technical Solution To achieve the goals of good impurity removal and more energy-efficient overall process, this invention provides the following technical solution: a purification process for high-purity quartz sand production, comprising the following steps: Step S1, Raw ore pretreatment: The raw ore is subjected to crushing, grinding, classification, magnetic separation, scrubbing, concentration and dewatering to obtain fine-grained quartz sand concentrate; Step S2, Classification Washing and Precision Microfiltration: The quartz concentrate slurry after flotation is subjected to multi-stage countercurrent washing and polymer composite material microfiltration to obtain primary purified quartz material; Step S3, High-temperature chlorination roasting: After dehydration, the primary purified quartz material is roasted in a chlorine-containing atmosphere at 1000℃-1300℃ to obtain chlorinated purified quartz sand. Step S4, High-temperature vacuum dehydroxylation: The chlorinated purified quartz sand is heat-treated under a vacuum of less than 10⁻³ Pa and a temperature of 1200℃~1500℃ to obtain dehydroxylated quartz sand. Step S5, Secondary Cleaning Treatment: The dehydroxylated quartz sand is subjected to secondary scrubbing and precise classification to obtain clean quartz sand slurry; Step S6, Online Analysis and Intelligent Diversion: Perform online elemental analysis on the clean quartz mortar and divert it into products of different purity grades based on the analysis results.
[0008] Preferably, the detailed steps in step S1 are as follows: S1.1 Crushing and Closed-Circuit Screening: After the raw ore is crushed by the jaw crusher, it is sent to the vibrating screen by the belt conveyor for screening. The material on the screen is returned to the crusher by the belt conveyor to form a closed circuit, and the material under the screen enters the powder ore bin. S1.2 Grinding and Classification: The material in the powder ore bin is fed to the linear vibrating screen by the feeding equipment. The material on the screen enters the wet rod mill, and the material under the screen and the discharge from the rod mill enter the first-stage obstructed settling tank for classification. The underflow of the first-stage obstructed settling tank is returned to the rod mill for re-grinding, and the overflow enters the second-stage obstructed settling tank for secondary classification. S1.3 Magnetic separation to remove iron: The underflow of the two-stage obstructed settling tank is passed through a weak magnetic separator and a strong magnetic separator in sequence to remove strong magnetic iron and weak magnetic iron impurities; S1.4 Scrubbing and product separation: The iron-removed slurry is sent to a first-stage hydrocyclone for classification, and its underflow enters a first-stage scrubbing machine for scrubbing; the scrubbing product is classified by a second-stage hydrocyclone, and its overflow is output as fine-grained quartz sand concentrate, while its underflow is returned to the scrubbing machine for secondary scrubbing to obtain coarse-grained quartz sand concentrate. S1.5 Concentration and Dewatering: The overflows of the first-stage hydrocyclone, the second-stage hydrocyclone, and the second-stage obstructed settling tank are combined and sent to a thickener for concentration. The underflow is then dewatered to obtain the fine-grained quartz sand concentrate.
[0009] Preferably, in step S2, the washing step includes: S2.1, Primary washing: The quartz concentrate slurry is subjected to at least 3 stages of countercurrent washing using circulating process water or primary pure water; S2.2, Composite microfiltration: The slurry after primary washing is pumped into a polymer composite material microfiltration system for cross-flow filtration, wherein the rated filtration accuracy of the microfiltration system is 0.1~0.5 micrometers; S2.3, Final Wash: The quartz filter cake retained by microfiltration is finally washed with hot pure water with a resistivity ≥18MΩ•cm.
[0010] Preferably, in step S2.2, the filtrate generated by the polymer composite microfiltration system is purified and reused for the primary washing in step S2.1, forming a local water circulation.
[0011] Preferably, in step S3, the chlorine-containing atmosphere is Cl2, HCl, or a mixture of Cl2 and an inert gas; the calcination is carried out in a rotary kiln or a fluidized bed reactor for 1 to 4 hours.
[0012] Preferably, in step S4, the heat treatment is carried out in a high-temperature vacuum furnace, with a holding time of 2 to 6 hours and a heating rate of 5 to 10 °C / min.
[0013] Preferably, step S5 further includes: S5.1, Secondary scrubbing: In a cleanroom environment, the dehydroxylated quartz sand is mixed with pure water and high-purity ceramic abrasive media for mechanical scrubbing; S5.2, Precision Classification: The washed slurry is classified by a high-precision hydrocyclone group or centrifugal classifier to separate the qualified particle size of the quartz sand slurry.
[0014] Preferably, in step S5.1, the high-purity ceramic grinding media is a zirconium oxide or alumina ceramic ball; in step S5.2, the overflow generated during grading is returned to step S1 as replenishment water or returned to step S5.1 for recycling.
[0015] Preferably, in step S6, the online elemental analysis employs a laser-induced breakdown spectroscopy (LIBS) online analyzer or a microwave plasma mass spectrometry (MP-MS) sampling and analysis system to monitor at least three of the elements Al, Fe, Ti, B, Ca, Na, and K in real time.
[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides a purification process for the production of high-purity quartz sand, which has the following beneficial effects: 1. The purification process used in the production of high-purity quartz sand removes more than 80% of easily removable impurities through multi-stage crushing, grading, magnetic separation, and scrubbing, resulting in qualified fine-grained concentrate and providing a high guarantee for the overall quality of the sand and gravel. Furthermore, by introducing the core steps of "high-temperature chlorination roasting" and "high-temperature vacuum dehydroxylation," key impurities such as aluminum (Al) and boron (B) that exist in the quartz lattice in an isomorphic form can be effectively removed, further reducing the total impurity content of the product and thus improving the purity of the product.
[0017] 2. The purification process for producing high-purity quartz sand employs a three-stage treatment: primary washing with circulating water, polymer composite microfiltration, and fine washing with a small amount of pure water. Combined with filtrate reuse, this forms a local water circulation, reducing overall energy consumption. The high-temperature vacuum dehydroxylation step effectively eliminates the structural hydroxyl groups (-OH) in the quartz particles. The "secondary cleaning treatment" removes high-temperature sintering aggregates, significantly improving the final quartz sand product's resistance to crystallization (devitrification), bubble rate, and optical uniformity during subsequent high-temperature smelting. Attached Figure Description
[0018] Figure 1 This is a perspective view of the present invention. Detailed Implementation
[0019] The technical solutions 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 skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1: Industrial Production of Photovoltaic-Grade High-Purity Quartz Sand This embodiment aims to provide an efficient, stable and cost-controllable industrial production solution for preparing high-purity quartz sand with a purity between 99.99% and 99.995% (4N-4N5), mainly used in photovoltaic quartz crucibles and other fields.
[0021] Step S1, Raw ore pretreatment: The raw ore is natural quartzite. First, the raw ore is crushed to a particle size of less than 50mm by a jaw crusher. Then, it is fed into a double-layer vibrating screen by a belt conveyor. The material oversizes the +10mm screen back to the crusher to form a closed circuit. The material between the -10mm and +20 mesh screens enters the buffer bin. The material undersizes the -20 mesh screen directly enters the subsequent classification stage. The material in the buffer bin is evenly fed into a wet rod mill by a bar feeder. The discharge from the rod mill and the aforementioned -20 mesh material are pumped together into a set of 250mm diameter hydrocyclones (instead of the obstructed settling device in the embodiment) for classification. The underflow (coarse sand) from the hydrocyclone returns to the rod mill for re-grinding, and the overflow (fine sand) enters the secondary hydrocyclone group for secondary classification and control. The underflow from the secondary hydrocyclone enters the subsequent magnetic separation, and the overflow (containing a large amount of fine mud) enters the thickener. The magnetic separation adopts a "coarse-sweep" process: the underflow from the secondary hydrocyclone is first coarsened by a medium-intensity permanent magnet drum magnetic separator (background field strength approximately 4000 Gauss) to remove strongly magnetic impurities; the coarsened concentrate then enters a high-gradient electromagnetic slurry magnetic separator (background field strength ≥ 1.2 Tesla) for sweeping to deeply remove weakly magnetic iron minerals. After iron removal, the slurry is dewatered and then enters the scrubbing process; in this embodiment, a high-efficiency, high-power scrubbing machine is used, with 0.05 wt% sodium hexametaphosphate added as a dispersant, scrubbing at a high concentration of 70% for 30 minutes to strongly peel off the thin film of iron and attached impurities on the particle surface; after scrubbing, the product is classified by a hydrocyclone group to separate quartz sand concentrate that meets the particle size requirements, and finally concentrated by a high-efficiency thickener and dewatered by a chamber filter press to obtain fine-grained quartz sand concentrate filter cake with a moisture content of <18%, which is then used for later use; Step S2, graded washing and precision microfiltration: The quartz sand filter cake obtained in step S1 is adjusted to a concentration of 30% and first enters a three-stage countercurrent washing system. This system uses the circulating process water (conductivity <50μS / cm) that has been treated by sedimentation and filtration for washing. Through efficient solid-liquid displacement, more than 85% of residual flotation reagents and soluble salts can be removed. After washing, the slurry is pumped into a polymer composite microfiltration system using a polyvinylidene fluoride (PVDF) hollow fiber membrane. The membrane has a nominal pore size of 0.2 microns and operates in cross-flow filtration mode. This system can effectively intercept quartz particles and remove submicron-sized impurities, colloids, and dissolved impurities with the depth of the filtrate, resulting in a product water turbidity <0.1 NTU. The quartz concentrate after microfiltration is finally sprayed and washed with a small amount of hot pure water with a resistivity ≥10MΩ•cm and a temperature of 60℃. The consumption of fresh ultrapure water in this step is reduced by about 65% compared to the traditional full-process ultrapure water washing process. After simple neutralization and filtration, the microfiltration filtrate is reused for primary washing, forming a local water circulation. Step S3, High-temperature chlorination roasting: The quartz sand filter cake after fine washing in step S2 is dried in a low-temperature dryer until the moisture content is <5%, and then sent to an externally heated rotary kiln. A mixed gas consisting of 30% by volume Cl2 and 70% Ar is introduced into the kiln, and calcination is carried out at a core reaction zone temperature of 1150℃. The material residence time is about 2.5 hours. Under these conditions, the aluminum, iron, titanium and other metallic impurities in the quartz lattice and at the interface are oxidized and generate gaseous chlorides (such as AlCl3, FeCl3) which volatilize and escape. These chlorides are absorbed and treated by the alkaline spray tower at the kiln tail. This step can reduce the content of the above-mentioned key metallic impurities by an order of magnitude. Step S4, High-temperature vacuum dehydroxylation: After chlorination, the quartz sand was cooled to room temperature under nitrogen protection and then placed into a high-temperature vacuum furnace with high-purity graphite as the heating element. The furnace was then evacuated to a vacuum level of 5 × 10⁻⁶. - The temperature is increased to 1350℃ at a rate of 8℃ / min and held at this temperature for 4 hours. During this process, the structural hydroxyl groups (Si-OH) in the quartz particles combine to generate water molecules and are removed. At the same time, the particle surface undergoes micro-melting, becoming smoother and denser, which significantly improves the high-temperature stability of the product. Step S5, Secondary Cleaning Treatment: The dehydroxylated quartz sand undergoes secondary treatment in a Class 10,000 cleanroom. First, it is mixed with pure water with a resistivity ≥15MΩ•cm and high-purity alumina ceramic balls in a certain proportion. Then, it is gently scrubbed in a clean-type agitator to remove trace amounts of volatile residues that may be attached to the surface. After scrubbing, the slurry is precisely classified by a laboratory-grade hydrocyclone (such as the D10MM type) to accurately separate quartz sand slurry with the target particle size distribution (such as -140 mesh + 325 mesh) to ensure uniform particle size of the product. Step S6: Online Analysis and Intelligent Triage: Before final product packaging, the slurry is tested in real time using a laser-induced breakdown spectroscopy (LIBS) online analyzer, with a focus on monitoring the content of three key elements: Fe, Al, and Ca. The control system automatically controls the three-way distribution valve according to preset thresholds (e.g., Fe < 8 ppm, Al < 25 ppm for "photovoltaic grade 1") to divert the product to different storage tanks, which are then labeled as "photovoltaic grade 1" and "photovoltaic grade 2" finished products, respectively.
[0022] Example 2: Precision preparation of semiconductor-grade ultra-high purity quartz sand To illustrate the universality and scalability of the process framework of this invention, the following demonstrates that by strengthening the process conditions, this solution can also be applied to cutting-edge fields such as semiconductors where extreme purity requirements exist. This embodiment is intended to demonstrate the potential of the basic process of this invention, rather than as a cost-optimal recommended solution.
[0023] Step S1, Raw ore pretreatment: The crushing, grinding, and classification processes are similar to those in Example 1, but all parts of the equipment that come into contact with the material are equipped with polyurethane or high-chromium alloy wear-resistant liners to minimize the introduction of mechanical iron; the magnetic separation process uses a superconducting magnetic separator to circulate the slurry multiple times at extremely low flow rates to ensure that the magnetic impurity removal rate is >99.9%; the scrubbing process is carried out in a specially made polymer scrubbing tank where no metal ions are dissolved, using a purified dispersant; Step S2, graded washing and precision microfiltration: In this embodiment, all washing water is electronic-grade ultrapure water with a resistivity ≥18.2MΩ•cm, and all pipelines and tanks are made of PVDF or high-purity quartz. The microfiltration system uses PTFE composite flat sheet membrane with a pore size of 0.1 micrometers that has undergone special hydrophilic modification treatment on the surface, and operates in a constant-temperature clean room. The fine washing uses ultrapure water at 85℃ to ensure that the particle surface reaches atomic-level cleanliness. All wastewater is collected to a dedicated waste liquid recovery system for deep treatment and recycling. Step S3, High-temperature chlorination roasting: The dried quartz sand is loaded into a fluidized bed reactor, which is then purged with high-purity chlorine gas (99.999% purity) for deep chlorination at 1280°C, with the reaction time extended to 4 hours. The fluidized bed design ensures full contact between the gas and solid phases, which is particularly beneficial for removing difficult-to-remove impurities such as boron (B) and phosphorus (P) that enter the quartz lattice in an isomorphic form, reducing them to the ppb level. Step S4, High-temperature vacuum dehydroxylation: This step is carried out in a cold-walled high-temperature vacuum furnace, where the furnace vacuum level must be reached and maintained below 1×10⁻⁶ before heating. - The temperature is increased to 1500℃ at a slow rate of 5℃ / min and held at this extreme temperature for 6 hours. This process not only completely removes the structural hydroxyl groups, but also promotes the full melting and lattice reconstruction of the quartz particle surface, achieving high densification, which gives it excellent resistance to crystallization and deformation in the subsequent semiconductor single crystal pulling process. Step S5, Secondary Cleaning Treatment: The cleaning medium used is high-purity zirconia ceramic microspheres ultrasonically cleaned with ultrapure water. The ultrapure water is 18.2 MΩ•cm ultrapure water generated online in real time. The grading equipment is a centrifugal classifier made entirely of PFA (soluble polytetrafluoroethylene) material, which is operated in a clean room. Step S6: Online Analysis and Intelligent Triage: A microwave plasma mass spectrometry (MP-MS) sampling and analysis system is adopted. This system automatically takes samples from the production line every 10 minutes and performs ppb-level quantitative analysis on more than 15 trace and ultra-trace elements such as Al, B, Ti, Fe, Na, K, Ca, and Li in the samples. After analysis, the products are automatically and precisely diverted to the "electronic grade", "fiber optic grade" and "semiconductor grade" finished product warehouses to ensure the reliability and traceability of product quality.
[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A purification process for producing high-purity quartz sand, characterized in that, Includes the following steps: Step S1, Raw ore pretreatment: The raw ore is subjected to crushing, grinding, classification, magnetic separation, scrubbing, concentration and dewatering to obtain fine-grained quartz sand concentrate; Step S2, Classification Washing and Precision Microfiltration: The quartz concentrate slurry after flotation is subjected to multi-stage countercurrent washing and polymer composite material microfiltration to obtain primary purified quartz material; Step S3, High-temperature chlorination roasting: After dehydration, the primary purified quartz material is roasted in a chlorine-containing atmosphere at 1000℃-1300℃ to obtain chlorinated purified quartz sand. Step S4, High-temperature vacuum dehydroxylation: The chlorinated purified quartz sand is heat-treated under a vacuum of less than 10⁻³ Pa and a temperature of 1200℃~1500℃ to obtain dehydroxylated quartz sand. Step S5, Secondary Cleaning Treatment: The dehydroxylated quartz sand is subjected to secondary scrubbing and precise classification to obtain clean quartz sand slurry; Step S6, Online Analysis and Intelligent Diversion: Perform online elemental analysis on the clean quartz mortar and divert it into products of different purity grades based on the analysis results.
2. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, The detailed steps in step S1 are as follows: S1.1 Crushing and Closed-Circuit Screening: After the raw ore is crushed by the jaw crusher, it is sent to the vibrating screen by the belt conveyor for screening. The material on the screen is returned to the crusher by the belt conveyor to form a closed circuit, and the material under the screen enters the powder ore bin. S1.2 Grinding and Classification: The material in the powder ore bin is fed to the linear vibrating screen by the feeding equipment. The material on the screen enters the wet rod mill, and the material under the screen and the discharge from the rod mill enter the first-stage obstructed settling tank for classification. The underflow of the first-stage obstructed settling tank is returned to the rod mill for re-grinding, and the overflow enters the second-stage obstructed settling tank for secondary classification. S1.3 Magnetic separation to remove iron: The underflow of the two-stage obstructed settling tank is passed through a weak magnetic separator and a strong magnetic separator in sequence to remove strong magnetic iron and weak magnetic iron impurities; S1.4 Scrubbing and product separation: The iron-removed slurry is sent to a first-stage hydrocyclone for classification, and its underflow enters a first-stage scrubbing machine for scrubbing; the scrubbing product is classified by a second-stage hydrocyclone, and its overflow is output as fine-grained quartz sand concentrate, while its underflow is returned to the scrubbing machine for secondary scrubbing to obtain coarse-grained quartz sand concentrate. S1.5 Concentration and Dewatering: The overflows of the first-stage hydrocyclone, the second-stage hydrocyclone, and the second-stage obstructed settling tank are combined and sent to a thickener for concentration. The underflow is then dewatered to obtain the fine-grained quartz sand concentrate.
3. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, In step S2, the washing step includes: S2.1, Primary washing: The quartz concentrate slurry is subjected to at least 3 stages of countercurrent washing using circulating process water or primary pure water; S2.2, Composite microfiltration: The slurry after primary washing is pumped into a polymer composite material microfiltration system for cross-flow filtration, wherein the rated filtration accuracy of the microfiltration system is 0.1~0.5 micrometers; S2.3, Final Wash: The quartz filter cake retained by microfiltration is finally washed with hot pure water with a resistivity ≥18MΩ•cm.
4. The purification process for producing high-purity quartz sand according to claim 3, characterized in that, In step S2.2, the filtrate generated by the polymer composite microfiltration system is purified and reused for the primary washing in step S2.1, forming a local water circulation.
5. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, In step S3, the chlorine-containing atmosphere is Cl2, HCl, or a mixture of Cl2 and an inert gas; the calcination is carried out in a rotary kiln or a fluidized bed reactor for 1 to 4 hours.
6. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, In step S4, the heat treatment is carried out in a high-temperature vacuum furnace for 2 to 6 hours, with a heating rate of 5 to 10 °C / min.
7. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, Step S5 also includes: S5.1, Secondary scrubbing: In a cleanroom environment, the dehydroxylated quartz sand is mixed with pure water and high-purity ceramic abrasive media for mechanical scrubbing; S5.2, Precision Classification: The washed slurry is classified by a high-precision hydrocyclone group or centrifugal classifier to separate the qualified particle size of the quartz sand slurry.
8. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, In step S5.1, the high-purity ceramic grinding media is zirconium oxide or alumina ceramic balls; in step S5.2, the overflow generated during grading is returned to step S1 as replenishment water or returned to step S5.1 for recycling.
9. The purification process for producing high-purity quartz sand according to claim 1, characterized in that, In step S6, the online elemental analysis employs a laser-induced breakdown spectroscopy (LIBS) online analyzer or a microwave plasma mass spectrometry (MP-MS) sampling and analysis system to monitor at least three of the elements Al, Fe, Ti, B, Ca, Na, and K in real time.