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Method of lowering content of calcium in recovered cryolite

A cryolite and calcium content technology, applied in aluminum fluoride, aluminum halide and other directions, can solve the problems that the calcium content cannot meet the index requirements, the quality of recovered cryolite is not high, and the recycling of cryolite is affected, and the method is simple and economical. Raw materials, strong operability effect

Active Publication Date: 2018-12-11
河南宏氟环保科技有限公司
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Problems solved by technology

[0004] However, although the above method can separate the cryolite from the electrolytic aluminum waste slag and the graphite carbon powder and use it for recycling, the quality of the recovered cryolite is not high, and the calcium content (expressed as CaO) in it usually cannot meet the index requirements
The calcium element in the cryolite recovered by the above method is mainly in the form of CaF 2 Exist in the form of cryolite, insoluble in water, difficult to remove, thus affecting the recycling of cryolite

Method used

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  • Method of lowering content of calcium in recovered cryolite

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Embodiment 1

[0025] See figure 1 , the embodiment of the present invention provides a kind of method that reduces the calcium content in reclaiming cryolite, it comprises the following steps:

[0026] Step 1, providing a cryolite recovered from electrolytic aluminum waste slag by flotation, calcium fluoride in the recovered cryolite;

[0027] Step 2, detecting that the content of calcium fluoride in the recovered cryolite is 3.5 wt.%, adding the sodium carbonate solution with a concentration of 1 mol / L to the recovered cryolite, and the recovered The solid-to-liquid ratio of the cryolite to the added sodium carbonate solution is 1:1, stirring continuously for 3 h, so that the calcium fluoride in the recovered cryolite reacts with sodium carbonate to generate calcium carbonate, and a solid-liquid mixture containing calcium carbonate is obtained The solid-liquid mixture containing calcium carbonate is separated and processed to obtain calcium carbonate-containing cryolite and sodium carbona...

Embodiment 2

[0033] The present embodiment provides a kind of method that reduces calcium content in reclaiming cryolite, and the method that this method provides with embodiment 1 is substantially the same, and difference is:

[0034] In described step 2, the content of the calcium fluoride in the cryolite of described recovery is 2.7 wt.%, the concentration of described sodium carbonate solution is 0.5 mol / L, the cryolite of described recovery and the sodium carbonate that adds The solid-liquid ratio of the solution is 1:2, stirring for 2 h; the step of obtaining the sodium carbonate recovery solution comprises: filtering the solid-liquid mixture containing calcium carbonate to obtain the sodium carbonate filtrate and the cryolite precursor containing calcium carbonate; The cryolite precursor containing calcium carbonate is washed with water to obtain the cryolite containing calcium carbonate and the washing liquid containing sodium carbonate; the sodium carbonate filtrate and the washing...

Embodiment 3

[0037] This embodiment provides a method for reducing the calcium content in the recovered cryolite, which is basically the same as the method provided in Example 1, except that in the step 2, the fluorination in the recovered cryolite The content of calcium is 4.4 wt.%, the concentration of described sodium carbonate solution is 3 mol / L, and the solid-liquid ratio of described cryolite and the sodium carbonate solution that adds is 1: 1.5; In described step 3, The calcium content in the final cryolite product is 0.5 wt %.

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Abstract

The invention provides a method of lowering the content of calcium in recovered cryolite. The method comprises the following steps of providing a kind of cryolite recovered from electrolytic aluminiumwaste slag, wherein the recovered cryolite contains calcium fluoride; adding an excess sodium carbonate solution into the recovered cryolite according to the content of the calcium fluoride in the recovered cryolite, and performing reaction on the calcium fluoride in the recovered cryolite with the sodium carbonate solution to obtain cryolite containing calcium carbonate; and sequentially performing acid pickling, washing and drying treatments on the cryolite containing calcium carbonate to remove calcium carbonate to obtain a finished cryolite product. The method can effectively remove the calcium fluoride in the recovered cryolite; and the content of the calcium in the recovered cryolite treated with the method can be lowered by 90 percent or above.

Description

technical field [0001] The invention belongs to the field of aluminum chemical industry, in particular to a method for reducing calcium content in recovered cryolite. Background technique [0002] Cryolite, the chemical name is sodium hexafluoroaluminate or sodium aluminum fluoride, and the molecular formula is Na 3 AlF 6 , white fine crystals. Cryolite is mainly used as a flux for aluminum electrolysis, and can also be used as a wear-resistant filler for rubber and grinding wheels, an enamel opalescent agent, a glass sunscreen and a metal flux, and an insecticide for crops. Cryolite consumes a lot in the electrolytic aluminum production process, and a considerable part of it remains in the electrolytic aluminum waste slag. Electrolytic aluminum waste slag includes electrolytic cell waste cathode slag, waste cathode carbon block, cathode paste, anode paste, scum taken out during electrolysis of aluminum, and tank wall refractory materials with cathode paste attached. Acc...

Claims

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Application Information

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IPC IPC(8): C01F7/54
CPCC01F7/54C01P2006/80
Inventor 王建设张青娥杨贵军赵建宏程相林王留成宋成盈
Owner 河南宏氟环保科技有限公司
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