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Process for recovering fluoride salt from aluminium electrolyzing anode 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: 2006-04-26
GUIZHOU BRANCH CHINA ALUMINUM IND
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Problems solved by technology

However, the above method has difficulties such as high cost, large pollution, difficult disposal of waste liquid, and low recovery rate of fluoride salt, which is not conducive to industrial scale implementation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Control the weight of anode carbon slag in the raw material treated by pyrolysis to 60%, and add it in the form of particles smaller than 5mm; the weight of industrial alumina is 40%, and mix it evenly into the anode carbon slag; use heavy oil as fuel to spray into the rotary kiln for combustion , the treatment temperature is controlled at 800°C, and the tail gas is adsorbed by alumina.

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

Embodiment 2

[0022] Control the content of anode carbon slag in the raw materials for fire treatment to 70%, and add it in the form of particles smaller than 5mm; add 30% of industrial alumina, and mix it evenly into the anode carbon slag; use gas as fuel to inject into the rotary kiln for combustion, and process The temperature is controlled at 850°C, and the tail 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 product purity meets the requirements for electrolytic cells. The recovery rate of total fluoride salt was 99.39%.

Embodiment 3

[0025] Control the content of anode carbon slag in the raw materials for fire treatment to 50%, and add it in the form of particles smaller than 5mm; the amount of industrial alumina is 50%, and mix it evenly into the anode carbon slag; use heavy oil as fuel and spray it into the rotary kiln for combustion. The temperature is controlled at 750°C, and the tail 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 for the use of electrolytic cells. The recovery rate of total fluoride salt was 99.71%.

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Abstract

A method for recovering fluoride salt in aluminum electrolysis anode carbon slag, relates to a treatment method for anode carbon slag produced in the process of aluminum electrolysis, in particular to a method for recovering fluoride salt in anode carbon slag. It is characterized in that the process is to add aluminum oxide to the anode carbon slag as a dispersant, and the weight ratio of the aluminum oxide as a dispersant to the total material is 10%-60%, and a liquid or a fuel with ash content of less than 1% is used Gas fuel is roasted at a temperature of 650°C-930°C until the carbonaceous material in the carbon residue is completely burned, the tail gas is adsorbed by alumina, and the fluoride salt is retained and recovered. The processed product contains about 15%-70% alumina and 30%-85% fluoride salt, with very little impurity content, and can be directly and completely returned to the electrolytic tank for use, without adverse effects on the quality of electrolyte and molten aluminum.

Description

technical field [0001] A method for recovering fluoride salt in aluminum electrolysis anode carbon slag, relates to a treatment method for anode carbon slag produced in the process of aluminum electrolysis, in particular to a method for recovering fluoride salt in anode carbon slag. Background technique [0002] A large amount of anode carbon slag containing fluoride salts is produced in the electrolytic aluminum production process. Usually about 3-10 kg of anode carbon slag is produced for every ton of primary aluminum produced, and the output anode carbon slag contains about 70% fluoride salt (mainly sodium fluoride and cryolite), which mainly comes from In the electrolyte, it is an extremely valuable electrolysis raw material. At present, due to the inability to effectively recover the fluoride salt and return it to be used as electrolyte, the consumption of fluoride salt is large and the production cost of electrolytic aluminum is increased. [0003] In the past, the m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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