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Method for preparing cryolite

A technology of cryolite and wastewater, applied in the direction of aluminum fluoride, silicon dioxide, aluminum halide, etc., can solve the problems of limited quality improvement of silicon content, concentration limit, and unsatisfactory volume of products, so as to facilitate the recycling and reuse of resources , mild conditions, and achieve the effect of resource recycling

Active Publication Date: 2019-05-24
INST OF PROCESS ENG CHINESE ACAD OF SCI
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Problems solved by technology

The ammonium fluoroaluminate method uses ammonium fluoroaluminate waste slag produced by the aluminum profile industry as raw materials for fluorine and aluminum, and reacts with caustic soda / soda ash / industrial sodium chloride to produce cryolite, but its volume cannot meet the requirements of the entire industry for cryolite products. needs
Although the sodium fluorosilicate method can realize the resource utilization of sodium fluorosilicate or potassium fluorosilicate by-products in industries such as phosphate fertilizers, it is limited to the treatment of solid sodium fluorosilicate raw materials, and thus brings about changes in the concentration of pre-order fluorosilicate restrictions, and the quality improvement of the silicon content of its products is limited

Method used

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Examples

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Embodiment 2

[0070] This example provides a method for preparing cryolite and silica by-products from waste water containing silicon and fluorine. The waste water containing silicon and fluorine used is: acid waste water containing silicon and fluorine obtained from the condensate of a fluidized bed waste gas from an aluminum fluoride plant in Hunan. , the wastewater composition (g / L, the same below) is as described in Table 2:

[0071] Table 2

[0072]

[0073] Specifically include the following steps:

[0074] (1) Mix silicon-fluorine-containing acidic wastewater with the concentrated ammonia water obtained from the rectification top of Example 1, and carry out a chemical desiliconization reaction. The reaction temperature is 90°C, and the desiliconization reaction time is 0.5h. 4 + and F in acidic wastewater containing silicon and fluorine - The mol ratio is 1.05:1, obtains desiliconization reaction slurry;

[0075] Liquid-solid separation and washing of the filter cake to obtain...

Embodiment 3

[0082] Except that the reaction temperature of the chemical desiliconization reaction is 50° C. and the desilication reaction time is 4 h, other preparation methods and conditions are the same as those in Example 1.

[0083] SiO in the cryolite product that present embodiment obtains 2 The mass fraction is 0.086%.

Embodiment 4

[0085] Except that the cryolite synthesis reaction temperature is 100° C. and the synthesis time is 1.5 h, other preparation methods and conditions are the same as in Example 2.

[0086] SiO in the cryolite product that present embodiment obtains 2 The mass fraction is 0.042%.

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Abstract

The invention relates to a method for preparing cryolite. The method comprises the steps that 1) wastewater containing silicon and fluorine is mixed with ammonium hydroxide, and a chemical desiliconization reaction is carried out; 2) liquid-solid separation is carried out to obtain white carbon black and an ammonium fluoride desiliconized liquid; 3) the ammonium fluoride desiliconized liquid is mixed with a sodium aluminate solution, and a synthesis reaction is carried out; 4) liquid-solid separation is carried out to obtain the cryolite. The method for preparing the cryolite has the advantages that a high-quality cryolite product is obtained by recycling from the wastewater containing the silicon and fluorine and a white carbon black byproduct is also obtained; the recovery rate of fluorine resources in the wastewater is 90% or above, the obtained cryolite has high purity and good fluidity, and the mass fraction of SiO2 is less than 0.1%; the raw material can be acidic fluorine-containing wastewater discharged from the aluminum fluoride industry, fluorosilicic acid discharged from the phosphate fertilizer industry or ammonium fluoride alkaline wastewater discharged from the niobium and tantalum industry, and the resource recovery rates of fluorine and silicon are not affected; the process conditions are mild, high-efficiency circulation of the medium is easily achieved, the industrial operability is strong, and the economic benefits are outstanding.

Description

technical field [0001] The invention belongs to the field of resource recovery, and relates to a method for preparing cryolite, in particular to a method for recovering and preparing cryolite from waste water and producing white carbon black by-product. Background technique [0002] Sodium hexafluoroaluminate (cryolite) is a commonly used electrolytic flux. It is often used as a flux for alumina electrolysis and refining pure aluminum. It has good stability, high melting point, is not easy to decompose and volatilize, and has good conductivity; it is used as electrode coating and multi-metal welding processing flux; used as enamel opalescent agent, glass or enamel production as opacifying agent and flux; used as resin additive and wear-resistant filler for rubber and grinding wheels, crop insecticide, metal flux, olefin polymerization Catalyst; It can also be used as artificial stone, glass anti-reflection coating, laser mirror coating, edge trimming agent for steel, etc. D...

Claims

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Application Information

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IPC IPC(8): C01F7/54C01B33/12
Inventor 曹绍涛张毅曹宏斌
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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