Process for recovering fluoride salt from aluminium electrolyzing carbon slag

A technology of fluoride salt and aluminum recovery, which is applied in the direction of fluoride preparation, etc., can solve the problems of unfavorable industrial scale implementation, low recovery rate of fluoride salt, difficult disposal of waste liquid, etc., and achieves easy industrial scale implementation, low treatment cost, The effect of high recovery rate

Active Publication Date: 2005-03-02
GUIZHOU BRANCH CHINA ALUMINUM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above method has difficulties such as high cost, large pollution, difficult disposal of waste

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 60% by weight of anode carbon slag in raw materials treated by controlled fire method, added in the form of particles smaller than 5mm; 40% by weight of industrial alumina, mixed evenly into anode carbon slag; heavy oil as fuel is sprayed into rotary kiln for combustion , The treatment temperature is controlled at 800℃, and the exhaust gas is adsorbed by alumina.

[0020] After analysis, the total fluoride salt (including sodium fluoride, cryolite and calcium fluoride) content in the product is 51.41%, calcium fluoride is 1.93%, and alumina content is 48.58%. The purity of the product meets the requirements of the electrolytic cell. The salt recovery rate was 99.52%.

Embodiment 2

[0022] The content of anode carbon slag in the raw materials treated by the controlled fire method is 70%, which is added in the form of particles less than 5mm; the amount of industrial alumina is 30%, which is evenly mixed into the anode carbon slag; the coal gas is sprayed into the rotary kiln for combustion and treatment The temperature is controlled at 850℃, and the exhaust gas is adsorbed by alumina.

[0023] After analysis, the total fluoride salt (including sodium fluoride, cryolite and calcium fluoride) content in the product is 62.27%, of which calcium fluoride is 1.66%; the alumina content is 37.72%, and the purity of the product meets the requirements of the electrolytic cell. The total fluoride salt recovery rate is 99.39%.

Embodiment 3

[0025] The content of anode carbon slag in the raw materials treated by the controlled fire method is 50%, and it is added in the form of particles less than 5mm; the amount of industrial alumina is 50%, which is evenly mixed into the anode carbon slag; the heavy oil is sprayed into the rotary kiln for combustion and treatment The temperature is controlled at 750°C, and the exhaust gas is adsorbed by alumina.

[0026] After analysis, the total fluoride salt (including sodium fluoride, cryolite and calcium fluoride) content in the product is 41.25%, of which calcium fluoride is 2.06%; the alumina content is 58.74%, and the product purity meets the requirements of the electrolytic cell. The total fluoride salt recovery rate was 99.71%.

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PUM

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Abstract

The present invention relates to the treating method of anode carbon slag produced in aluminum electrolyzing process, and is especially the process of recovering fluoride salt from anode carbon slag. The present invention features that anode carbon slag is compounded with alumina as dispersant in the amount of 10-60 wt% of the total material and liquid or gas fuel with ash content less than 1 % is used to roast the carbon slag at 650-930 deg.c for completely burning out carbon material in the carbon slag. The tail gas is adsorbed with alumina and the fluoride salt is recovered. The treated product contains alumina in 15-70 wt%, fluoride salt in 30-85 wt% and few impurity, and may be returned to electrolysis bath for reuse without negative effect on the electrolyte and aluminum liquid quality.

Description

Technical field [0001] A method for recovering fluoride salt in anode carbon slag of aluminum electrolysis relates to a method for processing anode carbon slag generated in an aluminum electrolysis process, in particular a method for recovering fluoride salt in anode carbon slag. Background technique [0002] A large amount of anode carbon slag containing fluoride salt is produced during the production of electrolytic aluminum. Usually, about 3-10 kg of anode carbon slag is produced for every 1 ton of primary aluminum produced, and the anode carbon slag produced contains about 70% of fluoride salt (mainly sodium fluoride and cryolite), and the fluoride salt is mainly derived from For electrolyte, it is extremely valuable electrolysis raw material. At present, the fluoride salt cannot be effectively recovered and returned for use as an electrolyte, resulting in a large consumption of fluoride salt and an increase in the production cost of electrolytic aluminum. [0003] In the pas...

Claims

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Application Information

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IPC IPC(8): C01B9/08
Inventor 李旺兴陈喜平刘凤琴罗钟生
Owner GUIZHOU BRANCH CHINA ALUMINUM IND
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