Ultra-white quartz sand and preparation process thereof

Abstract

The invention discloses ultra-white quartz sand, raw materials for manufacturing the ultra-white quartz sand comprise quartz ore and a composite fluxing agent, raw materials for manufacturing the composite fluxing agent comprise sodium chloride powder and potassium chloride, the mass fraction of the quartz ore is 100 parts, and the mass fraction of the composite fluxing agent is 0.9-1.1 parts. The high-purity quartz ore and high-precision color sorting equipment are adopted, visible impurities and part of harmful impurities are preliminarily removed, a good foundation is laid for the subsequent process, the arranged composite pickling solution contains hydrochloric acid, concentrated sulfuric acid and oxalic acid, compared with a single pickling solution, different types of impurities can be removed in a targeted mode, and the production efficiency is improved. The removal rate of impurities such as iron and aluminum is obviously improved; and secondly, sodium chloride powder and potassium chloride are added as fluxing agents in the drying and calcining process, and two-stage calcining and inert gas protection are adopted, so that trace impurities can be further removed, the crystal structure of the quartz ore can be optimized, and the whiteness and purity of the product can be improved.

Description

Technical Field

[0001] This invention relates to the field of quartz sand processing technology, specifically to an ultra-white quartz sand and its preparation process. Background Technology

[0002] Quartz sand is an important industrial raw material, widely used in glass manufacturing, ceramic glazes, electronic materials, precision casting, water treatment, and many other fields. With the rapid development of high-end manufacturing, higher requirements have been placed on the whiteness and purity of quartz sand. For example, industries such as high-end float glass, electronic-grade silicon materials, and optical glass require ultra-white quartz sand with a whiteness of ≥99.5% and extremely low impurity content.

[0003] Currently, the whiteness of ordinary quartz sand produced in the industry is generally between 40 and 90, which is difficult to meet the needs of the aforementioned high-end industries. Existing quartz sand whitening processes mainly include physical sorting, acid washing to remove impurities, and high-temperature calcination. However, when it is necessary to produce quartz sand with a whiteness content higher than 99%, the existing traditional production processes are difficult to achieve. Furthermore, the impurities in the raw materials and the calcination process cannot meet the requirements of the production process for high-whiteness quartz sand, making it difficult to further improve whiteness and control impurity content. Therefore, we propose an ultra-white quartz sand and its preparation process. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-white quartz sand and its preparation process to solve the problems that need to be solved in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an ultra-white quartz sand, wherein the raw materials for manufacturing the ultra-white quartz sand include quartz ore and a composite flux, wherein the raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride, wherein the mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 0.9-1.1 parts, and the mass ratio of sodium chloride to potassium chloride is 10:1-1.5.

[0006] As a further description of the above technical solution:

[0007] A process for preparing ultra-white quartz sand includes the following steps:

[0008] Step 1: Mineral processing: Select quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material. Then remove impurities such as stones and weathered layers from the quartz ore. Send the screened quartz ore to a crusher for crushing. After crushing, screen the quartz ore through a 50-180 mesh screen to obtain quartz ore powder.

[0009] Step 2: Acid washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fractions of the acid washing solution are 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:65. After weighing the acid washing solution and quartz ore powder, add them to the inside of a stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 50℃-55℃ using an automatic temperature control system, and stir at a speed of 200-260 r / min for 5-6 hours. After stirring, discharge the material for deacidification.

[0010] Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%.

[0011] Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

[0012] Currently, the whiteness of ordinary quartz sand produced in the industry is generally between 40 and 90, which is insufficient to meet the needs of the aforementioned high-end industries. Existing quartz sand whitening processes mainly include physical sorting, acid washing to remove impurities, and high-temperature calcination. However, when it is necessary to produce quartz sand with a whiteness content higher than 99%, the existing traditional production processes are difficult to achieve. Furthermore, the impurities in the raw materials and the calcination process cannot meet the requirements for producing high-whiteness quartz sand, making it difficult to further improve whiteness and control impurity content. This invention strictly controls the purity of raw materials through mineral processing and effectively removes dark-colored impurities by combining crushing and color sorting, laying the foundation for high whiteness. Secondly, it adopts... Using a specific ratio of composite pickling solution, under optimized temperature, stirring speed, and time conditions, metal ions and lattice impurities are efficiently removed, significantly improving whiteness. Secondly, after pickling, the product is thoroughly rinsed with high-purity water until conductivity meets standards, preventing secondary contamination. Finally, during the calcination stage, a composite flux of 0.1% is added, combined with two-stage heating, which not only promotes impurity volatilization but also improves the crystal structure, synergistically enhancing the product's whiteness to over 99.8. This setup ensures the entire process is stable and controllable, resulting in ultra-white quartz sand that meets the stringent requirements of high-end glass, photovoltaics, and semiconductors for ultra-high whiteness and high purity, demonstrating outstanding industrial application value and economic benefits.

[0013] As a further description of the above technical solution:

[0014] After the quartz ore is screened in step one, it is crushed and sent to a CCD image recognition color sorter to remove dark impurity particles. The recognition accuracy of the CCD image recognition color sorter is 0.05mm, and the color sorting threshold is set so that particles with a gray value ≤180 are judged as dark impurities. The CCD image recognition color sorter adopts a dual-lens cross-set configuration.

[0015] As a further description of the above technical solution:

[0016] The room temperature pure water used in step three has a conductivity of less than 5 uS / cm, and the wastewater after rinsing has a conductivity of less than 5 uS / cm is then dehydrated.

[0017] As a further description of the above technical solution:

[0018] In step four, the drying and calcining process, the first stage calcination temperature is 280℃-300℃ and the calcination time is 25-30 min; the second stage calcination temperature is 600℃-650℃ and the calcination time is 55-60 min.

[0019] As a further description of the above technical solution:

[0020] The stainless steel pickling tank is lined with a polytetrafluoroethylene (PTFE) layer with a thickness of 2-3 mm. The joint between the PTFE layer and the stainless steel pickling liner is sealed by heat fusion.

[0021] As a further description of the above technical solution:

[0022] In step three, rinsing, the rinsing process adopts a multi-stage countercurrent rinsing process with 3-5 rinsing tanks. In step four, drying and calcining, the kiln adopts an electric heating method, and the temperature uniformity inside the kiln is ±5℃.

[0023] As a further description of the above technical solution:

[0024] It also includes a PCL control system, which is used to control the operation of steps one through four.

[0025] As a further description of the above technical solution:

[0026] During the calcination process in the kiln, an inert gas, either nitrogen or argon, is introduced into the kiln at a flow rate of 0.5-2 L / min, and the oxygen content inside the kiln is less than 10 ppm.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. First, this invention uses high-purity quartz ore and high-precision color sorting equipment to initially remove visible impurities and some harmful impurities, laying a good foundation for subsequent processes. The composite pickling solution contains hydrochloric acid, concentrated sulfuric acid and oxalic acid. Compared with a single pickling solution, it can specifically remove different types of impurities, and the removal rate of impurities such as iron and aluminum is significantly improved.

[0029] 2. Secondly, sodium chloride powder and potassium chloride are added as fluxes during the drying and calcination process, and two-stage calcination and inert gas protection are adopted. This not only further removes trace impurities, but also optimizes the crystal structure of quartz ore and improves the whiteness and purity of the product.

[0030] 3. Finally, a multi-stage countercurrent rinsing process is adopted, combined with conductivity detection, to ensure that acid and soluble salts on the surface of quartz ore can be completely removed, avoiding residual impurities from affecting the whiteness and stability of the product. At the same time, water resources are saved and production costs are reduced. Moreover, the preparation method has a standardized operation process and controllable parameters, making it suitable for large-scale industrial production. The product can be widely used in high-end glass manufacturing, electronic packaging materials, precision casting and other industries with extremely high requirements for the whiteness and purity of quartz sand. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the system principle of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0033] Example 1:

[0034] Please see Figure 1 The present invention provides a technical solution: an ultra-white quartz sand, wherein the raw materials for manufacturing the ultra-white quartz sand include quartz ore and a composite flux, wherein the raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride, wherein the mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 0.9-1.1 parts, and the mass ratio of sodium chloride to potassium chloride is 10:1-1.5.

[0035] As a further description of the above technical solution:

[0036] A process for preparing ultra-white quartz sand includes the following steps:

[0037] Step 1: Mineral Processing: Quartz ore with a silica content greater than 99% and an alumina content less than 0.5% is selected as the production base material. This ore has the characteristics of low impurity content and good crystallinity, which lays the foundation for the subsequent preparation of ultra-white quartz sand. Then, impurities such as stones and weathered layers are removed from the quartz ore. The screened quartz ore is sent to a crusher for crushing. After crushing, it is screened through a 50-180 mesh screen to obtain quartz ore powder. This particle size range is not only conducive to the full contact between acid and impurities in the subsequent pickling process, but also meets the usage requirements of most high-end industries.

[0038] Step 2: Acid Washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fraction of the acid washing solution is 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:65. After weighing the acid washing solution and quartz ore powder, add them to the stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 50℃-55℃ using an automatic temperature control system, and stir at a speed of 200-260 r / min for 5-6 hours. After stirring, discharge the material for deacidification. At this temperature, the acid solution has high reactivity, which can significantly improve the impurity removal efficiency. The stirring uniformity is ≤5% to ensure that the acid solution and quartz sand particles are in full contact. The acid washing time is controlled at 5-6 hours to allow the impurities to fully dissolve in the acid solution. Then, open the discharge valve at the bottom of the tank to separate the acid solution from the quartz sand, completing the deacidification process.

[0039] Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%.

[0040] Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

[0041] The use of quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material reduces impurities within the quartz ore at the source, removes weathered layers and impurities, ensuring high purity and good crystallinity of the raw material. Combined with 50-180 mesh particle size control, this facilitates acid penetration and meets the particle size requirements of high-end applications, initially improving the whiteness of the finished quartz sand. The subsequent acid washing solution is prepared using hydrochloric acid, concentrated sulfuric acid, and oxalic acid. Concentrated sulfuric acid has strong oxidizing and dehydrating properties, decomposing some insoluble impurities and removing organic matter; oxalic acid has a strong effect on iron ions. It exhibits excellent complexation properties, effectively removing iron salt precipitates generated during pickling and preventing secondary contamination. This ratio ensures a sufficient supply of pickling solution while avoiding acid waste. Hydrochloric acid, with its high volatility and corrosiveness, rapidly dissolves soluble metal oxides such as iron, calcium, and magnesium on the surface of quartz sand, significantly improving whiteness and purity. Step three involves thorough rinsing with room-temperature pure water, controlling the moisture content to ≤5%, to prevent secondary contamination from residual acid or impurities. Finally, step four introduces a composite flux and employs a two-stage calcination process, which not only promotes the volatilization of residual impurities but also optimizes the quartz crystal structure, further enhancing the product's whiteness and thermal stability. The overall process is controllable and efficient, yielding ultra-white quartz sand with high whiteness, meeting the stringent performance requirements of raw materials in photovoltaic glass, semiconductor packaging, and high-end optical devices.

[0042] Example 2:

[0043] Please see Figure 1 After the quartz ore is screened in step one, it is crushed and sent to a CCD image recognition color sorter to remove dark impurity particles. The recognition accuracy of the CCD image recognition color sorter is 0.05mm, and the color sorting threshold is set so that particles with a gray value ≤180 are judged as dark impurities. The CCD image recognition color sorter adopts a dual-lens cross setting, especially for visible impurities with a particle size ≥0.1mm, which initially improves the whiteness of the quartz sand.

[0044] By setting a recognition accuracy of 0.05mm and a color sorting threshold of grayscale value ≤180, it can accurately identify and remove dark-colored impurity particles such as iron-containing manganese minerals or mica that are difficult to distinguish with the naked eye. In particular, it can efficiently intercept visible impurities with a particle size ≥0.1mm. Secondly, by adopting a dual-lens cross-set structure, it can simultaneously capture the surface color and texture information of quartz particles from multiple angles, effectively avoiding single-view occlusion or misjudgment, and greatly improving the color sorting accuracy and stability.

[0045] The room temperature pure water used in step three has a conductivity of less than 5 uS / cm, and the wastewater after rinsing has a conductivity of less than 5 uS / cm is then dehydrated.

[0046] The high-purity water has an extremely low impurity ion content, which effectively avoids the introduction of new metal ions or anionic contaminants during the rinsing process, ensuring the high purity of the quartz sand. Secondly, using a wastewater conductivity of ≤5uS / cm as the criterion ensures that residual hydrochloric acid, sulfuric acid, oxalic acid, and their soluble metal salts generated during pickling are completely removed, preventing these impurities from re-attaching or forming oxides and discoloring during subsequent drying and calcination, thus affecting the final whiteness. In addition, thorough rinsing also prevents corrosive components such as chloride ions from remaining on the surface of the quartz sand, improving the chemical stability and reliability of the product in high-end applications. The dehydration treatment controls the moisture content to ≤5%, which not only prevents moisture from interfering with the calcination process but also avoids particle agglomeration, ensuring the product's flowability and particle size uniformity.

[0047] In step four, the drying and calcining process, the first stage calcination temperature is 280℃-300℃ and the calcination time is 25-30 min; the second stage calcination temperature is 600℃-650℃ and the calcination time is 55-60 min.

[0048] The first stage of calcination, set at a low temperature of 280℃-300℃, effectively removes residual moisture, organic matter, and some volatile acid radicals from the surface and pores of quartz sand particles. This prevents them from rapidly vaporizing at high temperatures, which could lead to particle cracking or structural defects. It also prevents impurities from reacting with quartz in a solid phase at high temperatures, making them difficult to remove. The second stage of calcination, at a medium temperature of 600℃-650℃, promotes the further decomposition or volatilization of residual metal oxide impurities without causing crystal transformation in quartz, thus maintaining the integrity of the crystal structure and preventing microcracks or a decrease in whiteness due to phase transformation. Furthermore, the two-stage heating allows for gradient utilization of thermal energy, reducing thermal stress damage to the particles and improving the mechanical strength and particle size stability of the product.

[0049] The stainless steel pickling tank is lined with a polytetrafluoroethylene (PTFE) layer with a thickness of 2-3 mm. The joint between the PTFE layer and the stainless steel pickling liner is sealed by heat fusion.

[0050] The process involves adding a uniformly mixed pickling solution and quartz sand into a stainless steel pickling tank lined with polytetrafluoroethylene (PTFE). The PTFE lining has excellent corrosion resistance, which can prevent the acid from corroding the tank and introducing new impurities. The joint between the PTFE layer and the stainless steel pickling lining is sealed with a heat-melt seal to prevent the pickling solution from moving to the gap between the PTFE layer and the stainless steel pickling lining.

[0051] In step three, rinsing, the rinsing process adopts a multi-stage countercurrent rinsing process with 3-5 rinsing tanks. In step four, drying and calcining, the kiln adopts an electric heating method, and the temperature uniformity inside the kiln is ±5℃.

[0052] Among these measures, gradually reducing acid residue on the surface of quartz sand improves rinsing efficiency and saves water resources. Furthermore, controlling the uniformity of temperature inside the kiln can prevent secondary oxidation of the quartz sand.

[0053] It also includes a PCL control system, which is used to control the operation of steps one to four. The PCL control system can be set to automatically realize the automation of steps one to four, avoiding excessive manual intervention that could affect the whiteness of the quartz sand after production.

[0054] During the calcination process in the kiln, an inert gas, either nitrogen or argon, is introduced into the kiln at a flow rate of 0.5-2 L / min, and the oxygen content inside the kiln is less than 10 ppm.

[0055] In particular, the introduction of inert gases such as nitrogen or argon during the calcination process in the kiln, and the strict control of the oxygen content in the furnace to below 10 ppm, can effectively inhibit the oxidation reaction of trace metal impurities in quartz sand at high temperatures in an extremely low oxygen environment, avoiding the formation of highly colored high-valence metal oxides, thereby significantly improving the whiteness and optical transparency of the product. Secondly, the inert atmosphere can prevent side reactions between the surface of quartz particles and oxygen or water vapor at high temperatures, reduce the formation of defect structures such as hydroxyl groups, and improve the thermal stability and dielectric properties of the material. In addition, the stable inert atmosphere can also prevent the flux from being oxidized or decomposed at high temperatures, ensuring that it effectively promotes the volatilization of impurities and lattice repair during the calcination process. At the same time, controlling the inert gas flow rate within the range of 0.5-2 L / min can maintain positive pressure in the furnace, prevent the infiltration of external air, and avoid excessive airflow causing heat loss or particle disturbance, thus ensuring calcination uniformity and energy efficiency.

[0056] Example 3:

[0057] The raw materials for manufacturing ultra-white quartz sand include quartz ore and composite flux. The raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride. The mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 0.9 parts, and the mass ratio of sodium chloride to potassium chloride is 10:1.

[0058] The preparation process of the aforementioned ultra-white quartz sand includes the following steps:

[0059] Step 1: Mineral processing: Select quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material. Then remove impurities such as stones and weathered layers from the quartz ore. Send the screened quartz ore to a crusher for crushing. After crushing, screen the quartz ore through a 50-mesh sieve to obtain quartz ore powder.

[0060] Step 2: Acid washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fractions of the acid washing solution are 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:65. After weighing the acid washing solution and quartz ore powder, add them into the stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 50°C using an automatic temperature control system and stir at a speed of 200 r / min for 5 hours. After stirring, discharge the material for deacidification.

[0061] Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%.

[0062] Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

[0063] Example 4:

[0064] The raw materials for manufacturing ultra-white quartz sand include quartz ore and composite flux. The raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride. The mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 1.1 parts, and the mass ratio of sodium chloride to potassium chloride is 10:1.5.

[0065] The preparation process of the aforementioned ultra-white quartz sand includes the following steps:

[0066] Step 1: Mineral processing: Select quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material. Then remove impurities such as stones and weathered layers from the quartz ore. Send the screened quartz ore to a crusher for crushing. After crushing, screen the quartz ore through a 180-mesh sieve to obtain quartz ore powder.

[0067] Step 2: Acid washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fractions of the acid washing solution are 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:65. After weighing the acid washing solution and quartz ore powder, add them into the stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 55°C using an automatic temperature control system, and stir at a speed of 260 r / min for 6 hours. After stirring, discharge the material for deacidification.

[0068] Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%.

[0069] Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

[0070] Example 5:

[0071] The raw materials for manufacturing ultra-white quartz sand include quartz ore and composite flux. The raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride. The mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 1 part, and the mass ratio of sodium chloride to potassium chloride is 10:1.25.

[0072] The preparation process of the aforementioned ultra-white quartz sand includes the following steps:

[0073] Step 1: Mineral processing: Select quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material. Then remove impurities such as stones and weathered layers from the quartz ore. Send the screened quartz ore to a crusher for crushing. After crushing, screen the quartz ore through a 110-mesh screen to obtain quartz ore powder.

[0074] Step 2: Acid washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fractions of the acid washing solution are 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:65. After weighing the acid washing solution and quartz ore powder, add them into the stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 53°C using an automatic temperature control system, and stir at a speed of 230 r / min for 5.5 hours. After stirring, discharge the material for deacidification.

[0075] Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%.

[0076] Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

[0077] 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 type of ultra-white quartz sand, characterized in that: The raw materials for manufacturing ultra-white quartz sand include quartz ore and a composite flux. The raw materials for manufacturing the composite flux include sodium chloride powder and potassium chloride. The mass fraction of the quartz ore is 100 parts, the mass fraction of the composite flux is 0.9-1.1 parts, and the mass ratio of sodium chloride to potassium chloride is 10:1-1.

5.

2. A process for preparing ultra-white quartz sand, applicable to the ultra-white quartz sand as described in claim 1, characterized in that: The preparation process of the aforementioned ultra-white quartz sand includes the following steps: Step 1: Mineral processing: Select quartz ore with a silica content greater than 99% and an alumina content less than 0.5% as the production base material. Then remove impurities such as stones and weathered layers from the quartz ore. Send the screened quartz ore to a crusher for crushing. After crushing, screen the quartz ore through a 50-180 mesh screen to obtain quartz ore powder. Step 2: Acid washing: Prepare an acid washing solution to acid wash the quartz ore powder. The acid washing solution includes hydrochloric acid, concentrated sulfuric acid, and oxalic acid. The mass fractions of the acid washing solution are 4.8 parts hydrochloric acid, 2.3 parts concentrated sulfuric acid, and 2.9 parts oxalic acid. The weight ratio of the acid washing solution to the quartz ore powder is 35:

65. After weighing the acid washing solution and quartz ore powder, add them to the inside of a stainless steel acid washing tank. Under normal pressure, control the reaction temperature at 50℃-55℃ using an automatic temperature control system, and stir at a speed of 200-260 r / min for 5-6 hours. After stirring, discharge the material for deacidification. Step 3: Rinsing: After the pickling solution is drained, the quartz ore powder is rinsed with room temperature pure water. After the quartz sand powder is rinsed, the quartz ore powder is dehydrated. The moisture content of the dehydrated quartz ore powder is ≤5%. Step 4: Drying and calcining: The dehydrated quartz sand ore powder is put into a quartz crucible, and a composite flux is added. After the quartz ore powder and composite flux are stirred evenly, they are sent into a kiln. The quartz ore powder is then calcined in two stages. After calcination, the quartz ore powder is naturally cooled to obtain ultra-white quartz sand.

3. The preparation process of ultra-white quartz sand according to claim 1, characterized in that: After the quartz ore is screened in step one, it is crushed and sent to a CCD image recognition color sorter to remove dark impurity particles. The recognition accuracy of the CCD image recognition color sorter is 0.05mm, and the color sorting threshold is set so that particles with a gray value ≤180 are judged as dark impurities. The CCD image recognition color sorter adopts a dual-lens cross-set configuration.

4. The preparation process of ultra-white quartz sand according to claim 3, characterized in that: The room temperature pure water used in step three has a conductivity of less than 5 uS / cm, and the wastewater after rinsing has a conductivity of less than 5 uS / cm is then dehydrated.

5. The preparation process of ultra-white quartz sand according to claim 4, characterized in that: In step four, the drying and calcining process, the first stage calcination temperature is 280℃-300℃ and the calcination time is 25-30 min; the second stage calcination temperature is 600℃-650℃ and the calcination time is 55-60 min.

6. The preparation process of ultra-white quartz sand according to claim 5, characterized in that: The stainless steel pickling tank is lined with a polytetrafluoroethylene (PTFE) layer with a thickness of 2-3 mm. The joint between the PTFE layer and the stainless steel pickling liner is sealed by heat fusion.

7. The preparation process of ultra-white quartz sand according to claim 6, characterized in that: In step three, rinsing, the rinsing process adopts a multi-stage countercurrent rinsing process with 3-5 rinsing tanks. In step four, drying and calcining, the kiln adopts an electric heating method, and the temperature uniformity inside the kiln is ±5℃.

8. The preparation process of ultra-white quartz sand according to claim 7, characterized in that: It also includes a PCL control system, which is used to control the operation of steps one through four.

9. The preparation process of ultra-white quartz sand according to claim 7, characterized in that: During the calcination process in the kiln, an inert gas, either nitrogen or argon, is introduced into the kiln at a flow rate of 0.5-2 L / min, and the oxygen content inside the kiln is less than 10 ppm.

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