Chlorination process for producing high-purity quartz sand

Abstract

The invention discloses a chlorination process for producing high-purity quartz sand, and relates to the technical field of quartz sand purification. In the first stage, a mixed atmosphere of chlorine-containing gas and non-chlorine gas in a specific ratio is adopted, and trace CO is introduced into the non-chlorine gas; and the sectioned high temperature is matched, and the reaction temperature with high front and low rear is adopted, so that the integrity of the quartz sand matrix is guaranteed. In the second stage, seamlessly and directly entering a low-chlorine-content gas atmosphere taking HCl as a main component to realize fine removal of impurities; by adjusting the gas flow rate and the rotation rate of the reaction container, a reinforced turbulent layer is formed in the reaction system, and dead angles formed by particle accumulation are eliminated. The two-stage chlorination process has a synergistic effect, so that the damage problems of cracking, pore enlargement and the like possibly caused in the high-temperature chlorination process are remarkably relieved, the final product is low in impurity content, and the structural quality of the product is also ensured.

Description

Technical Field

[0001] This invention relates to the field of quartz sand purification technology, specifically a chlorination process for producing high-purity quartz sand. Background Technology

[0002] Currently, the purification technology for high-purity quartz sand mainly involves acid leaching after flotation. However, this method is insufficient to remove impurities, especially alkali metals and alkaline earth metals, to meet the requirements for high-purity quartz sand. Instead, the purification depends on the characteristics of the raw ore, rendering the purification technology ineffective.

[0003] Currently, the publicly disclosed chlorination process patents are Tian Huiming's patent "Method and Chlorination Apparatus for Producing High-Purity Quartz Sand by High-Temperature Chlorination" and Wuhan University of Technology's "A Method for Preparing 5N Grade Quartz Sand for Quartz Crucibles by High-Temperature Oscillating Chlorination Roasting". Existing chlorination processes involve chlorinating the ore after crushing it into quartz sand, using Cl2 and HCl at a volume ratio of 1:1 for high-temperature chlorination. However, because the raw ore contains a large amount of non-quartz minerals, the chlorination effect is weakened by mica, feldspar, and other non-quartz minerals, failing to meet the chlorination requirements. Furthermore, the method used by Wuhan University of Technology requires multiple chlorination processes to achieve the desired effect. During the chlorination process, the quartz sand is repeatedly recrystallized to remove impurities. This method is not only difficult to control, but it also creates cracks in the particles, leaving Cl2 or chloride residues that are difficult to remove. In the subsequent fabrication of single-crystal crucibles, a large amount of chlorine-containing gas is generated, affecting the quality of the single-crystal crucibles.

[0004] This invention achieves the removal of impurity elements without chlorine residue through a continuous chlorination process using different atmosphere combinations. Summary of the Invention

[0005] The purpose of this invention is to provide a chlorination process for producing high-purity quartz sand, so as to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a chlorination process for producing high-purity quartz sand, comprising the following preparation steps:

[0007] (1) Quartz ore with a silica content of not less than 99.3% is crushed, floated and strongly magnetized. The quartz ore contains 99.31% SiO2 and the impurity contents are: Fe: 423ppm, Ca: 341ppm, Na: 350ppm, K: 212ppm, Al: 1823ppm, Li: 3ppm, Mg: 63ppm, Ba: 156ppm. The quartz sand particles are between 60-200 mesh, and prepared quartz sand is obtained.

[0008] (2) The prepared quartz sand is loaded into a rotary tube reactor and a mixed gas is introduced under normal pressure. The mixed gas contains 10%-20% Cl2 and 70%-80% HCl, with the remainder being non-chlorine gas. The temperature is raised to 1100℃-1200℃ and held for 30-40 minutes to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1000℃-1050℃ and held for 20-30 minutes to continuously remove residual impurities. At the same time, CO is used to reduce iron oxides to generate volatile pentacarbonyl iron to enhance iron removal.

[0009] (3) After the first stage, the gas atmosphere is switched directly. The mixed gas is still introduced under normal pressure, and the reaction tube rotates at a constant speed. The volume content of HCl in the mixed gas is 1%-10%, and the volume content of non-chlorine gas is 90%-99%. The temperature is controlled at 1000℃-1200℃, and the constant temperature reaction is 60-90min. The gas flow rate throughout the process is 2L / min-4L / min, forming turbulent enhanced contact.

[0010] (4) After the second stage, stop heating and cool down, switch to pure N2 to purge for 30 minutes; after discharge, wash with ultrasonic water at 60°C to remove residual chlorides on the surface, and finally dry at 120°C for 2 hours to obtain high-purity quartz sand.

[0011] Furthermore, the non-chlorine gas is one or a mixture of nitrogen, argon, or oxygen.

[0012] Furthermore, the radius of the rotating tubular reactor in step (2) is 0.5m.

[0013] Furthermore, the amount of material fed in a single step (2) is 80-120 kg.

[0014] Furthermore, the total gas flow rate in step (2) is 2L / min-4L / min.

[0015] Furthermore, the non-chlorine gas in step (2) contains CO.

[0016] Furthermore, the non-chlorine gas contains 1%-5% CO by volume.

[0017] Furthermore, in step (3), the rotational speed of the rotating tube is 6.5-7.5 rpm.

[0018] Furthermore, in step (4), the temperature is lowered to 200°C.

[0019] Furthermore, in step (4), the N2 purging flow rate is 5 L / min.

[0020] Furthermore, the ultrasonic water washing time in step (4) is 10 minutes.

[0021] Furthermore, a high-purity quartz sand obtained according to the high-purity quartz sand refining process described above, wherein the impurity content in the high-purity quartz sand is: Al less than 11ppm, Fe less than 0.5ppm, Ba less than 0.06ppm, Ca less than 0.9ppm, K less than 0.5ppm, Li less than 0.5ppm, Mg less than 0.05ppm, and Na less than 0.8ppm.

[0022] This invention designs a new process route and chlorination method for the chlorination process of high-purity quartz sand, and selects quartz sand selected according to particle size and SiO2 content standards as the treatment object; the chlorination process is divided into two stages.

[0023] The first stage involves targeted impurity removal. During the chlorination process, a mixture of Cl2, HCl, and other non-chlorine gases is introduced. Cl2 accounts for 10-20% of the mixed gas volume, and HCl accounts for 70-80%. The remainder is non-chlorine gas, which maintains a fixed volume of 10%. 1-5% CO is added to the non-chlorine gas to convert certain oxygen-sensitive trace metal impurities into forms more readily chlorinated by HCl. This stage primarily involves the large-scale introduction of Cl2-containing gases to react and remove alkali and alkaline earth metals from the quartz sand at high temperatures. The first half of the first stage is at 1100-1200℃ to rapidly remove most volatile impurities, while the second half is lowered to 1000-1050℃ to reduce excessive reaction and porosity on the quartz sand surface, while ensuring the reaction continues.

[0024] The second stage involves deep chlorination. After the first stage, the chlorination process begins directly. Compared to the first stage, the gas atmosphere changes in the second stage, introducing HCl and non-chlorine gases. The HCl gas volume content is 1-10%, and the non-chlorine gas volume content is 90-99%, with the temperature controlled at 1000-1200℃. By adjusting the gas flow rate to 2-4 L / min and matching it with the tube rotation speed, the equipment is designed with a 0.5m inner radius tube and a rotation speed of 6.5-7.5 rpm to create a turbulent flow layer. This ensures sufficient contact between the particle surface and the gas, improving impurity removal efficiency.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] 1. In the first stage, a specific ratio of chlorine-containing gas and non-chlorine gas is used to create a mixed atmosphere, with trace amounts of CO introduced by the non-chlorine gas. The high proportion of chlorine-containing gas can react efficiently with alkali metals and alkaline earth metals in quartz sand at high temperatures, generating volatile chlorides that are efficiently carried out. The trace amounts of CO convert oxygen-sensitive trace metal impurities into active forms that are more easily chlorinated by HCl, such as forming volatile carbonyl compounds, further improving the removal depth and efficiency of difficult-to-remove metals such as iron.

[0027] 2. The first stage is combined with segmented high temperature, adopting a reaction temperature that is high at the beginning and low at the end; the high temperature environment in the early stage is intended to quickly activate the reaction activity and ensure that most of the volatile impurities are completely removed; the moderate cooling in the later stage effectively reduces the excessive erosion of the surface of the quartz sand particles, avoids unnecessary pore enlargement and structural damage, and ensures the integrity of the quartz sand matrix.

[0028] 3. In the second stage, after the efficient removal of the main impurities in the first stage, the sand is seamlessly and directly introduced into a low-chlorine gas atmosphere dominated by HCl to deeply remove residual and difficult-to-remove trace metal impurities and harmful hydroxyl groups from the quartz sand, thus achieving fine removal of impurities.

[0029] 4. In the second stage, by adjusting the gas flow rate and the rotation speed of the reaction vessel, an enhanced turbulent layer is formed inside the reaction system. This dynamic environment ensures that the reactant gas is in full contact with the surface of each quartz sand particle, eliminating dead zones formed by particle accumulation and significantly improving gas utilization and impurity removal efficiency.

[0030] 5. The two-stage chlorination process works synergistically to break through the bottleneck of traditional methods in the deep removal of metal impurities, achieving an unprecedented purification depth. Through staged temperature control and a mild atmosphere in the second stage, the original structure of the quartz sand particles is effectively protected, and damage problems such as cracking and increased porosity that may be caused by the high-temperature chlorination process are significantly reduced. This results in a final product with not only low impurity content but also guaranteed structural quality. Detailed Implementation

[0031] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The following embodiments describe a method for testing various indicators of a chlorination process for producing high-purity quartz sand:

[0033] Purity: Ten samples of raw quartz ore, finished high-purity quartz sand from the examples and comparative examples were selected and tested by ICP-OES, and the average value was taken.

[0034] Porosity: Example 3 and Comparative Examples 6 and 7 were tested according to GB / T 21650.1.

[0035] Cracks: Example 3 and Comparative Examples 6 and 7 were tested according to GB / T 27788.

[0036] Example 1; (1) Quartz ore was initially crushed to coarse particles with a particle size of 50 mm by a jaw crusher; the coarse particles were further crushed to 10 mm by a cone crusher, and then finely crushed to 2 mm by a high-pressure roller mill; 60-mesh target particles were separated by a vibrating screen, and the oversize material was returned for further crushing; the undersize particles were mixed with water at a solid-liquid ratio of 1:3, and 10 wt% sulfuric acid was added as a pH adjuster to control the pH of the slurry to 2; octadecylamine hydrochloride was added as a cationic collector, and the amount added was 50 g. / t of ore, stirred for 10 minutes; after stirring, the flotation machine scrapes off impurities such as mica and feldspar foam, and the sediment is primary quartz sand; then the primary quartz sand is dehydrated to a moisture content of 15%, and fed into a wet high-intensity magnetic separator with a magnetic field strength of 2.0T, and separated three times to remove iron and titanium magnetic impurities; after magnetic separation, the quartz sand is washed with deionized water until the conductivity is 5μS / cm; then dried with hot air at 105℃ to a moisture content of 0.1%; the particle size is precisely controlled to 60 mesh by an ultrasonic sieve to obtain prepared quartz sand;

[0037] (2) The prepared quartz sand is loaded into a rotary tube reactor with a radius of 0.5m. The single feed amount is 80kg. A mixed gas is introduced under normal pressure. The mixed gas contains 20% Cl2 and 70% HCl by volume, with the remainder being nitrogen and carbon monoxide. The CO volume content in the remainder is 1%. The total gas flow rate is controlled at 2L / min. The temperature is raised to 1100℃ and held for 30min to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1000℃ and held for 20min to continuously remove residual impurities. At the same time, CO is used to reduce iron oxide to generate volatile pentacarbonyl iron to enhance iron removal.

[0038] (3) After the first stage, the gas atmosphere is switched directly. The mixed gas is still introduced under normal pressure, and the reaction tube rotates at a constant speed. The mixed gas contains 1% HCl and 99% nitrogen. The temperature is controlled at 1000℃ and the reaction is constant for 60 minutes. The gas flow rate is 2L / min throughout the process, and the rotation speed of the rotating tube is 6.5rpm to form turbulent enhanced contact.

[0039] (4) After the second stage, stop heating and cool down to 200°C at a rate of 10°C / min. Switch to pure N2 to purge for 30 min at a flow rate of 5 L / min. After discharge, wash with ultrasonic water at a frequency of 40 kHz, a water temperature of 60°C, and a time of 10 min to remove residual chlorides on the surface. Finally, dry at 120°C for 2 h to obtain high-purity quartz sand.

[0040] Example 2; (1) Quartz ore was initially crushed to coarse particles with a particle size of 45 mm by a jaw crusher; the coarse particles were then crushed to 7.5 mm by a cone crusher, and then finely crushed to 1.5 mm by a high-pressure roller mill; 130-mesh target particles were separated by a vibrating screen, and the oversize material was returned for further crushing; the undersize particles were mixed with water at a solid-liquid ratio of 1:3, and 10 wt% sulfuric acid was added as a pH adjuster to control the pH of the slurry to 2.5; octadecylamine hydrochloride was added as a cationic collector, and the amount added was... 50g / t of ore was stirred for 10 minutes. After stirring, the flotation machine scraped off impurities such as mica and feldspar foam, and the sediment was primary quartz sand. The primary quartz sand was then dehydrated to a moisture content of 15% and fed into a wet high-intensity magnetic separator with a magnetic field strength of 2.0T. The separator was divided three times to remove iron and titanium magnetic impurities. The quartz sand after magnetic separation was washed with deionized water until the conductivity was 5μS / cm. It was then dried with hot air at 105℃ to a moisture content of 0.3%. The particle size was precisely controlled to 130 mesh by an ultrasonic sieve to obtain prepared quartz sand.

[0041] (2) The prepared quartz sand is loaded into a rotary tube reactor with a radius of 0.5m. The single feed amount is 100kg. A mixed gas is introduced under normal pressure. The mixed gas contains 15% Cl2 and 75% HCl by volume, with the remainder being argon and carbon monoxide. The CO volume content in the remainder is 3%. The total gas flow rate is controlled at 3L / min. The temperature is raised to 1150℃ and held for 35min to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1025℃ and held for 25min to continue removing residual impurities. At the same time, CO is used to reduce iron oxide to generate volatile pentacarbonyl iron to enhance iron removal.

[0042] (3) After the first stage, the gas atmosphere is switched directly. The mixed gas is still introduced under normal pressure, and the reaction tube rotates at a constant speed. The mixed gas contains 5.5% HCl and 94.5% argon. The temperature is controlled at 1100℃ and the reaction is constant for 75 minutes. The gas flow rate is 3L / min and the rotation speed of the tube is 7rpm to form turbulent enhanced contact.

[0043] (4) After the second stage, stop heating and cool down to 200°C at a rate of 10°C / min. Switch to pure N2 to purge for 30 min at a flow rate of 5 L / min. After discharge, wash with ultrasonic water at a frequency of 40 kHz, a water temperature of 60°C, and a time of 10 min to remove residual chlorides on the surface. Finally, dry at 120°C for 2 h to obtain high-purity quartz sand.

[0044] Example 3; (1) Quartz ore was initially crushed to coarse particles with a particle size of 40 mm by a jaw crusher; the coarse particles were further crushed to 5 mm by a cone crusher, and then finely crushed to 1 mm by a high-pressure roller mill; 200 mesh target particles were separated by a vibrating screen, and the oversize material was returned for further crushing; the undersize particles were mixed with water at a solid-liquid ratio of 1:3, and 10 wt% sulfuric acid was added as a pH adjuster to control the pH of the slurry to 3; octadecylamine hydrochloride was added as a cationic collector, and the amount added was 50 g. / t of ore, stirred for 10 minutes; after stirring, the flotation machine scrapes off impurities such as mica and feldspar foam, and the sediment is primary quartz sand; then the primary quartz sand is dehydrated to a moisture content of 15%, and fed into a wet high-intensity magnetic separator with a magnetic field strength of 2.0T, and separated 3 times to remove iron and titanium magnetic impurities; after magnetic separation, the quartz sand is washed with deionized water until the conductivity is 5μS / cm; then dried with hot air at 105℃ to a moisture content of 0.5%; the particle size is precisely controlled to 200 mesh by an ultrasonic sieve to obtain prepared quartz sand;

[0045] (2) The prepared quartz sand is loaded into a rotary tube reactor with a radius of 0.5m. The single feed amount is 120kg. Mixed gas is introduced under normal pressure. The mixed gas has a Cl2 volume content of 10%, an HCl volume content of 80%, and the remainder is nitrogen and carbon monoxide. The CO volume content in the remainder is 5%. The total gas flow rate is controlled at 4L / min. The temperature is raised to 1200℃ and held for 40min to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1050℃ and held for 30min to continuously remove residual impurities. At the same time, CO is used to reduce iron oxide to generate volatile pentacarbonyl iron to enhance iron removal.

[0046] (3) After the first stage, the gas atmosphere is switched directly. The mixed gas is still introduced under normal pressure, and the reaction tube rotates at a constant speed. The mixed gas contains 10% HCl and 90% oxygen. The temperature is controlled at 1200℃ and the reaction is constant for 90 minutes. The gas flow rate is 4L / min throughout the process, and the rotation speed of the rotating tube is 7.5rpm to form turbulent enhanced contact.

[0047] (4) After the second stage, stop heating and cool down to 200°C at a rate of 10°C / min. Switch to pure N2 to purge for 30 min at a flow rate of 5 L / min. After discharge, wash with ultrasonic water at a frequency of 40 kHz, a water temperature of 60°C, and a time of 10 min to remove residual chlorides on the surface. Finally, dry at 120°C for 2 h to obtain high-purity quartz sand.

[0048] Comparative Example 1; The difference between Comparative Example 1 and Example 3 lies in step (2). Step (2) is changed to: 120 kg of prepared quartz sand is loaded into a rotating tubular reactor with a radius of 0.5 m. Mixed gas is introduced under normal pressure. The mixed gas contains 45% Cl2 and 45% HCl by volume, with the remainder being argon and carbon monoxide. The CO content in the remainder is 5%. The total gas flow rate is controlled at 4 L / min. The temperature is raised to 1200℃ and held for 40 min to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1050℃ and held for 30 min to continuously remove residual impurities. Simultaneously, CO is used to reduce iron oxide to generate volatile pentacarbonyl iron to enhance iron removal. The remaining steps are the same as in Example 3.

[0049] Comparative Example 2; The difference between Comparative Example 2 and Example 3 is the difference in step (2). Step (2) is changed to: the prepared quartz sand is loaded into a rotating tube reactor with a radius of 0.5m, and the single feed amount is 120kg. Mixed gas is introduced under normal pressure. The mixed gas has a Cl2 volume content of 10%, an HCl volume content of 80%, and the remainder is argon and carbon monoxide. The CO volume content in the remainder is 5%. The total gas flow rate is controlled at 4L / min. The temperature is raised to 1200℃ and held for 90min. The remaining steps are the same as in Example 3.

[0050] Comparative Example 3; The difference between Comparative Example 3 and Example 3 lies in step (2). Step (2) is changed to: 120 kg of prepared quartz sand is loaded into a rotating tubular reactor with a radius of 0.5 m. Mixed gas is introduced under normal pressure. The mixed gas contains 10% Cl2 and 80% HCl by volume, with the remainder being argon. The total gas flow rate is controlled at 4 L / min. The temperature is raised to 1200℃ and held for 40 min to remove alkali metal and alkaline earth metal impurities. Then the temperature is lowered to 1050℃ and held for 30 min to continuously remove residual impurities. Simultaneously, volatile pentacarbonyl iron is generated by reducing iron oxide with CO to enhance iron removal. The remaining steps are the same as in Example 3.

[0051] Comparative Example 4; The difference between Comparative Example 4 and Example 3 is the difference in step (3). Step (3) is changed to: After the first stage, the gas atmosphere is directly switched, and the mixed gas is still introduced under normal pressure; the volume content of HCl in the mixed gas is 10%, and the volume content of oxygen is 90%; the temperature is controlled at 1200℃, and the constant temperature reaction is 90min; the gas flow rate throughout is 4L / min, forming turbulent enhanced contact; the remaining steps are the same as in Example 3.

[0052] Comparative Example 5; The difference between Comparative Example 5 and Example 3 is that step (3) is omitted, and step (4) is changed to: After the first stage is completed, heating is stopped and the temperature is reduced to 200°C at a rate of 10°C / min. Pure N2 is then used for purging for 30 min at a flow rate of 5 L / min. After discharge, the material is ultrasonically washed with water at a frequency of 40 kHz, a water temperature of 60°C, and a time of 10 min to remove residual chlorides on the surface. Finally, the material is dried at 120°C for 2 h to obtain high-purity quartz sand. The remaining steps are the same as in Example 3.

[0053] Comparative Example 6; Comparative Example 6 is quartz sand prepared according to Example 6 of patent CN202510621813.0; specifically, quartz sand with a SiO2 content of 99.9941% was loaded into a roasting furnace. XRD analysis showed that the mineral phase of the sample was pure quartz phase, without any associated mineral impurities, that is, the impurity elements were present in the quartz sand lattice. H2 and Cl2 were introduced into the furnace, with contents of 0.3 and 1.1 times the total molar amount of impurity elements in the quartz sand, respectively. The dynamic roasting furnace was tilted at a horizontal angle of 20°, rotated at 30 r / min, and roasted at 1050℃ for 30 min. The roasting product was collected.

[0054] Comparative Example 7; The difference between Comparative Example 7 and Example 3 is the difference in step (3). Step (3) is changed to: After the first stage, the gas atmosphere is switched directly. The mixed gas is still introduced under normal pressure, and the reaction tube rotates at a constant speed. The mixed gas is introduced under normal pressure. The volume content of Cl2 in the mixed gas is 10%, the volume content of HCl is 80%, and the remainder is nitrogen and carbon monoxide. The volume content of CO in the remainder is 5%. The total gas flow rate is controlled at 4L / min. The temperature is controlled at 1200℃ and the constant temperature reaction is carried out for 90min. The total gas flow rate is 4L / min, and the rotation speed of the rotating tube is 7.5rpm to form turbulent enhanced contact. The remaining steps are the same as in Example 3.

[0055] Example of effect

[0056] Table 1 below shows the analysis results of impurity content in high-purity quartz sand from Examples 1-3 and Comparative Examples 1-5 of the present invention.

[0057] Table 1

[0058]

[0059] Table 2 below shows the performance analysis results of producing high-purity quartz sand using Example 3 and Comparative Examples 6-7 of the present invention.

[0060] Table 2

[0061]

[0062] A comparison of the purity analysis experimental data from Examples 1-3 and Comparative Examples 1-5 reveals that the first stage of this invention employs a specific ratio of chlorine-containing gas and non-chlorine gas mixtures, with trace amounts of CO introduced by the non-chlorine gas. The high proportion of chlorine-containing gas at high temperatures efficiently reacts with alkali and alkaline earth metals in the quartz sand, generating volatile chlorides that are efficiently removed. The trace amounts of CO transform oxygen-sensitive trace metal impurities into active forms more readily chlorinated by HCl, such as volatile carbonyl compounds, further enhancing the removal depth and efficiency of difficult-to-remove metals like iron. The first stage utilizes segmented high temperatures, employing a reaction temperature that is high initially and low later. The initial high-temperature environment aims to rapidly activate the reaction, ensuring that most volatile impurities are completely removed. The subsequent moderate cooling effectively reduces excessive erosion of the quartz sand particle surface, avoiding unnecessary porosity increase and structural damage, thus ensuring the integrity of the quartz sand matrix. In the second stage, after the efficient removal of major impurities in the first stage, the mixture seamlessly enters a low-chlorine gas atmosphere dominated by HCl to deeply remove residual, difficult-to-remove trace metallic impurities and harmful hydroxyl groups from the quartz sand, achieving precise impurity removal. The second stage, by adjusting the gas flow rate and the rotation speed of the reaction vessel, creates a reinforced turbulent layer within the reaction system. This dynamic environment ensures that the reactant gas makes full contact with the surface of each quartz sand particle, eliminating dead zones caused by particle accumulation and significantly improving gas utilization and impurity removal efficiency. A comparison of the porosity and crack data from Example 3 and Comparative Examples 6-7 reveals that this invention utilizes the synergistic effect of a two-stage chlorination process to effectively protect the original structure of the quartz sand particles, significantly mitigating damage problems such as cracking and increased porosity that may occur during the high-temperature chlorination process. This results in a final product with not only low impurity content but also guaranteed structural quality.

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A chlorination process for producing high purity quartz sand, characterized in that, The preparation process comprises the following steps: (1) crushing, flotation and strong magnetization of the quartz raw ore to obtain quartz sand particles between 60-200 meshes; (2) loading the prepared quartz sand into a rotating tube reactor, and introducing a mixed gas under normal pressure, wherein the volume content of Cl2 is 10%-20%, the volume content of HCl is 70%-80%, and the rest is non-chlorine gas; heating to 1100-1200℃ and maintaining for 30-40 min to remove alkali metal and alkaline earth metal impurities; then cooling to 1000-1050℃ and maintaining for 20-30 min to continuously remove residual impurities and simultaneously use CO to reduce iron oxides to generate volatile iron pentacarbonyl to strengthen iron removal; (3) after the first stage, directly switching the gas atmosphere, still introducing the mixed gas under normal pressure, while rotating the reaction tube at a constant speed; in the mixed gas, the volume content of HCl is 1%-10%, and the volume content of non-chlorine gas is 90%-99%; the temperature is controlled at 1000-1200℃, and the constant temperature reaction is performed for 60-90 min; the total gas flow is 2-4 L / min to form a turbulent flow to strengthen the contact; (4) after the second stage, stopping heating and cooling, switching to pure N2 purging for 30 min; after discharging, performing ultrasonic water washing at a water temperature of 60℃ for 10 min to remove surface chloride residues, and finally drying at 120℃ for 2 h to obtain high-purity quartz sand products.

2. A chlorination process for producing high purity quartz sand according to claim 1, characterized in that, The non-chlorine gas is one or a mixture of nitrogen, argon or oxygen.

3. A chlorination process for producing high purity quartz sand according to claim 1, characterized in that, The radius of the rotating tube reactor in step (2) is 0.5 m.

4. A chlorination process for producing high purity quartz sand according to claim 1, characterized in that, The single feeding amount in step (2) is 80-120 kg.

5. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The total gas flow in step (2) is 2-4 L / min.

6. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The non-chlorine gas in step (2) contains CO.

7. A chlorination process for producing high purity quartz sand according to claim 6, characterized in that, The volume content of CO in the non-chlorine gas is 1%-5%.

8. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The rotating speed of the rotating tube body in step (3) is 6.5-7.5 rpm.

9. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The cooling rate in step (4) is 10℃ / min.

10. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The temperature in step (4) is cooled to 200℃.

11. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The N2 purging flow in step (4) is 5 L / min.

12. A chlorination process for producing high purity quartz sand as claimed in claim 1, wherein, The ultrasonic water washing time in step (4) is 10 min.

13. High purity quartz sand obtained by the high purity quartz sand refining process according to any one of claims 1 to 12, characterized in that In the high-purity quartz sand composition, the impurity content is: Al less than 11 ppm, Fe less than 0.5 ppm, Ba less than 0.06 ppm, Ca less than 0.9 ppm, K less than 0.5 ppm, Li less than 0.5 ppm, Mg less than 0.05 ppm, and Na less than 0.8 ppm.

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