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CN-121974359-A - Low-temperature high-efficiency chloridizing roasting purification method for high-purity quartz sand

CN121974359ACN 121974359 ACN121974359 ACN 121974359ACN-121974359-A

Abstract

The invention relates to a low-temperature high-efficiency chloridizing roasting purification method of high-purity quartz sand, and belongs to the technical field of quartz sand purification. The invention relates to a low-temperature high-efficiency chloridizing roasting purification method of high-purity quartz sand, which comprises the steps of firstly mixing pretreated and deeply dried quartz sand with a compound chloridizing agent containing NH 4 Cl、C 2 Cl 6 、NH 4 F, forming, then heating to 800-1000 ℃ in a programmed manner under the protection of inert atmosphere, and then switching to a mixed atmosphere containing 10-40% of HCl for constant-temperature chloridizing roasting for 2-8 hours. And cooling, crushing, cleaning and drying after roasting to obtain a high-purity quartz sand product. The invention obviously reduces the reaction temperature through the synergistic low-temperature chlorination of the compound chlorinating agent and the external HCl atmosphere, avoids quartz vitrification, efficiently removes metal impurities in crystal lattices and inclusion, has the advantages of low energy consumption, high safety, high product purity and the like, and can stably produce high-purity quartz sand with the grade of 4N8 and above.

Inventors

  • ZHENG KAI
  • LI GUANGSHI
  • Sun Chenteng
  • LI JIERUI
  • LU XIONGGANG
  • GAO WEIFAN
  • HU YONG

Assignees

  • 江西硅矿利用核心技术研发投资有限公司

Dates

Publication Date
20260505
Application Date
20260206

Claims (10)

  1. 1. The low-temperature high-efficiency chloridizing roasting purification method of the high-purity quartz sand is characterized by comprising the following steps of: S1, preprocessing raw materials, namely preprocessing quartz sand raw materials to obtain refined quartz sand; s2, drying, namely drying the refined quartz sand; S3, batching and forming, namely uniformly mixing the dried refined quartz sand and the composite chlorinating agent according to the mass ratio of 100 (0.5-5), and forming to obtain a quartz sand blank; wherein the compound chlorinating agent comprises ammonium chloride, hexachloroethane and ammonium fluoride, and the mass ratio of the ammonium chloride to the hexachloroethane to the ammonium fluoride is (10-15): 5-10): 1-3; s4, roasting the quartz sand blank at a low temperature under the mixed atmosphere of hydrogen chloride and inert gas at 800-1000 ℃ to obtain a roasted body; S5, cooling and post-treatment, namely cooling the roasting body in an inert atmosphere, and carrying out post-treatment on the roasting body to obtain a high-purity quartz sand product.
  2. 2. The method for purifying high-purity quartz sand by low-temperature efficient chloridizing roasting according to claim 1, wherein in the step S1, quartz sand raw materials are subjected to crushing, grinding, grading, magnetic separation, floatation and acid leaching treatment to obtain refined quartz sand, the granularity of the refined quartz sand is 100-300 meshes, and the SiO 2 content is more than 99.9%.
  3. 3. The method for purifying high purity silica sand by low temperature and high efficiency chloridizing roasting as claimed in claim 1, wherein in step S2, the refined silica sand is dried at 150-300 ℃ to have a water content of less than 0.01wt%.
  4. 4. The low-temperature efficient chloridizing roasting purification method of high-purity quartz sand according to claim 1, wherein the shaping in the step S3 is granulation or compression shaping, the particle size of a quartz sand blank is 3-15mm, and the quartz sand blank is in a granular or block shape.
  5. 5. The method for purifying high-purity quartz sand by low-temperature efficient chlorination roasting according to claim 1 or 4, wherein in the step S3, after the dried refined quartz sand and the compound chlorinating agent are uniformly mixed, a proper amount of binding agent is added according to 8-10wt% of the total weight of the refined quartz sand and the compound chlorinating agent, and the mixture is uniformly mixed and pressed to form the quartz sand blank.
  6. 6. The low-temperature efficient chloridizing roasting purification method of high-purity quartz sand according to claim 1, wherein in the step S3, the compound chloridizing agent is formed by mixing (10-15): (5-10): (1-3) of ammonium chloride, hexachloroethane and ammonium fluoride according to the mass ratio.
  7. 7. The method for purifying high-purity quartz sand by low-temperature efficient chlorination roasting according to claim 1, wherein in the step S4, the quartz sand blank is firstly placed in a closed roasting furnace, the temperature is raised to a target temperature of 800-1000 ℃ at a rate of 2-5 ℃ per minute under an inert atmosphere, the atmosphere is switched to a mixed atmosphere of hydrogen chloride and inert gas, and roasting is performed for 2-8 hours at 800-1000 ℃ to obtain a roasted body.
  8. 8. The method for purifying high purity silica sand by low temperature and high efficiency chloridizing roasting according to claim 1, wherein in step S4, the volume concentration of hydrogen chloride is 10-40% in the mixed atmosphere of hydrogen chloride and inert gas.
  9. 9. The method for purifying high purity silica sand by low temperature and high efficiency chloridizing roasting according to claim 1, wherein in step S5, the silica sand is cooled to below 100 ℃.
  10. 10. The method for purifying high purity silica sand by low temperature and high efficiency chlorination roasting according to claim 1, wherein the method for post-treating the roasted body comprises crushing, washing and drying in step S5.

Description

Low-temperature high-efficiency chloridizing roasting purification method for high-purity quartz sand Technical Field The invention relates to the technical field of quartz sand purification, in particular to a low-temperature efficient chloridizing roasting purification method of high-purity quartz sand. Background The high-purity quartz sand (5N grade, namely the purity is more than or equal to 99.999%) is a key base material of high and new technology industries such as semiconductors, optical fibers, photovoltaics and the like. The impurities in the quartz sand are mainly derived from non-quartz minerals of the ore and elements introduced in the processing process, and comprise metal oxides (Fe 2O3、Al2O3、Na2O、K2 O and the like), silicate minerals (feldspar, mica and the like), impurities in crystal lattices (Al 3+、Fe3+ and the like replace structural impurities formed by Si 4+) and fluid inclusion bodies (water, CO 2 and other gases which are wrapped in the quartz crystal and a small amount of salt). In the fields of semiconductors and photovoltaics, even if the quartz sand contains trace impurities, the quartz sand can have significant influence on product performance, such as silicon lattice defects, optical fiber signal attenuation, crucible deformation at high temperature and the like, so that the quartz sand needs to be purified to meet the use requirements. The conventional physical mineral separation (such as scrubbing, magnetic separation and floatation) and mixed acid impregnation treatment can effectively remove most of free impurities in the quartz sand, but has limited removal effect on impurities which are wrapped in the quartz crystal or replace silicon atoms to enter crystal lattices, and is difficult to economically and stably produce high-purity quartz sand with the grade of 4N8 (99.998 percent) and above. In the prior art, the quartz sand is purified by high-temperature chlorination, and the principle is that chlorine (Cl 2) or chloridizing agent such as hydrogen chloride (HCl) is introduced under the conditions of high temperature and certain atmosphere, so that metal impurities in the quartz sand are converted into chlorides (such as AlCl 3、FeCl3、TiCl4) with boiling points far lower than the reaction temperature, and the chlorides escape in a gas phase form, thereby realizing separation from quartz. However, in the existing technology for purifying quartz sand by high-temperature chlorination, the following significant defects exist: 1. The single chlorinating agent (such as NH 4 Cl or CaCl 2) is adopted for chloridizing and purifying, so that different types of impurities and inclusion bodies are difficult to remove at the same time and the removal rate of the impurities which are difficult to volatilize such as Al is low, and partial chlorinating agent (such as CaCl 2) is decomposed at high temperature to generate new decomposed substances (such as CaO) which are remained in quartz sand, so that new impurity elements can be possibly introduced; 2. the chlorination purification process is mostly carried out at a high temperature of more than 1250 ℃ and even 1400 ℃, huge energy consumption is required for maintaining the ultra-high temperature, and the production cost is high; 3. When chlorine is used as a chlorinating agent for purification, the high-temperature chlorine has extremely strong corrosiveness on the roasting furnace material, so that the service life of equipment is short and the maintenance cost is high; 4. when chlorine is used as a chlorinating agent for purification, the chlorine belongs to extremely toxic gas, and has extremely high requirements on storage, use and tail gas treatment, and leakage risk exists. Disclosure of Invention Based on the above, the invention aims to provide a low-temperature efficient chloridizing roasting purification method of high-purity quartz sand, which is based on a specific compound chloridizing agent and adopts a specific reaction atmosphere, so that deep chloridizing purification of quartz sand can be realized at a relatively low reaction temperature, the problems of energy consumption, safety, corrosion and the like caused by the adoption of high temperature in the traditional purification method are effectively solved, and the method has important significance for promoting cost reduction, synergy and technical progress of the high-purity quartz sand industry. In order to achieve the above purpose, the present invention adopts the following technical scheme: the invention provides a low-temperature high-efficiency chloridizing roasting purification method of high-purity quartz sand, which comprises the following steps: S1, preprocessing raw materials, namely preprocessing quartz sand raw materials to obtain refined quartz sand; s2, drying, namely drying the refined quartz sand; S3, batching and molding, namely uniformly mixing the dried refined quartz sand and (solid) compound chlorinating agent according to the mass ratio of 10