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Technique for purifying cryolite

A cryolite and process technology, applied in the field of purification process of by-product cryolite, can solve the problems of inability to electrolyze aluminum production, waste of resources, unfavorable environment, etc. simple effect

Inactive Publication Date: 2012-07-25
湖南有色金属投资有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, it cannot be directly used in the production of electrolytic aluminum
If this cryolite cannot be effectively used, it will not only cause a waste of resources, but also have an adverse impact on the environment.

Method used

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  • Technique for purifying cryolite
  • Technique for purifying cryolite
  • Technique for purifying cryolite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] (1) Add 400mL of water to a 2L reactor with stirring, and then add 200g of by-product cryolite under stirring to make a slurry; (2) Add 20g of mixed acid, in the mixed acid, HF:HCl:H 2 SO 4 The molar ratio is 1:0.3:0.3, heated to 55°C, and reacted for 30 minutes under stirring; (3) Vacuum-filter the reacted material to obtain a solid material, and dry it at 110°C for 2 hours. Obtain 193.5 grams of purified cryolite products, the rate of recovery is 96.75%. Analyze the impurity content in the product, the results are shown in Table 2.

[0017] Table 2 Example 1 product chemical composition analysis results (wt%)

[0018]

Embodiment 2

[0020] (1) Add 600mL of water to a 2L reactor with stirring, and add 200g of by-product cryolite under stirring to make a slurry; (2) Add 45g of mixed acid, in which HF:HCl:H 2 SO 4 The molar ratio is 1:0.45:0.45; heated to 60°C, and reacted for 60 minutes under stirring; (3) vacuum-filtered the reacted material to obtain a solid material, dried at 110°C for 2 hours, and it was ready. 193.8g of purified cryolite product was obtained; the recovery rate was 96.9%. Analyze the impurity content in the product, and the results are shown in Table 3.

[0021] Table 3 Example 2 product chemical composition analysis results (wt%)

[0022]

Embodiment 3

[0024] (1) Add 800mL of water to a 2L reactor with stirring, and add 200g of by-product cryolite under stirring to make a slurry; (2) Add 30 grams of mixed acid, in which HF:HCl:H 2 SO 4 The molar ratio is 1:0.6:0.6, heated to 85°C, and reacted for 90 minutes under stirring; (3) Vacuum-filter the reacted material to obtain a solid material, and dry it at 110°C for 2 hours. The purified cryolite product was 192.2g; the recovery rate was 96.1%. The impurity content in the analysis sample is shown in Table 4 for the results.

[0025] Table 4, Example 3 product chemical composition analysis results (wt%)

[0026]

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Abstract

The invention relates to a technique for purifying cryolite, and the technique comprises the following steps: (1) adding water and the cryolite into a reactor, wherein the mass ratio of the water to the cryolite is (0.5-6.0):1, and stirring, thus obtaining slurry; (2) adding HF-HCl-H2SO4 mixed acid into the slurry obtained in the step (1) while stirring, wherein the molar ratio of HF to HCl to H2SO4 is 1:(0.1-1):(0.1-1) in the mixed acid, and the mass ratio of the mixed acid to the raw material cryolite is (0.04-0.30):1; (3) heating the material obtained in the step (2) to 20-100 DEG C, and stirring for reaction for 10-150 minutes; and (4) carrying out vacuum filtration or centrifugal separation on a liquid-solid mixed material obtained in the reaction of the step (3), obtaining a solid material, and drying, thus obtaining the purified cryolite. The technique used for purifying the byproduct of cryolite is simple and low in energy consumption, and the recovery rate reaches more than 96%, so that the content of silicon dioxide in the cryolite and the ignition loss can be greatly reduced, and the treatment cost is low.

Description

technical field [0001] The invention relates to a process for purifying cryolite, more specifically, a process for purifying cryolite as a by-product in the production process of polysilicon. Background technique [0002] Cryolite is a white crystal or powder, which is an indispensable raw material in the process of producing aluminum metal by electrolysis. In industry, cryolite is generally produced in large quantities with fluorite, sulfuric acid, aluminum hydroxide, and soda ash as raw materials. Since fluorspar is a non-renewable strategic resource and there is a global shortage of fluorspar resources, the supply of fluorspar is becoming more and more tense. [0003] High-purity polysilicon is used as the basic raw material for the electronics industry and solar photovoltaic industry, and its output is growing rapidly. There is a new process for the production of polycrystalline silicon. During the production process, a by-product composed of cryolite (sodium fluoroalum...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/54
Inventor 廖志辉刘东晓段立山梁雅娟黎志坚曹德兴
Owner 湖南有色金属投资有限公司
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