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Method for producing cryolite from aluminum electrolysis waste slag

A technology of aluminum electrolysis and cryolite, applied in the direction of aluminum fluoride, aluminum halide, etc., can solve the problems of affecting current efficiency, limited scale, high cost of aluminum profiles, etc., and achieve economic benefits, low production costs, and solve stacking problems Effect

Inactive Publication Date: 2008-08-13
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the above adopting acidic fluorine-containing aluminum slag as raw material (ammonium fluoroaluminate) to prepare cryolite, its scale is limited by the amount of this acidic waste slag
Because the price of ammonium bifluoride and hydrofluoric acid used to treat the surface of aluminum profiles is relatively high, resulting in high costs for processing aluminum profiles, the amount of acid waste generated by this acid treatment of aluminum profiles is very limited.
[0003] With the development of the aluminum electrolysis industry, the consumption of cryolite is increasing day by day, and a large amount of aluminum electrolysis waste residue is also produced. These aluminum electrolysis waste residues contain a large amount of cryolite, but because they contain a large amount of carbon and other impurities, it seriously affects the current efficiency. Therefore, it cannot be directly used in aluminum electrolysis

Method used

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  • Method for producing cryolite from aluminum electrolysis waste slag

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example 1

[0008] Take 16kg of aluminum electrolysis waste residue, wet or dry grind it to below 60 mesh, after removing carbon and iron, put the treated waste residue into the reactor, add 8kg of concentrated sulfuric acid, start stirring and react at 25°C for 160min, the reaction The hydrogen fluoride gas generated is absorbed with water, and 30kg of water is added to the waste residue after acid hydrolysis, stirred for 2 minutes, and the residue is removed by filtration. The filtrate was put into the reactor, and 20% Na was slowly added under stirring condition. 2 CO 3 3.5kg of solution and 6kg of 30% hydrofluoric acid were reacted at a reaction temperature of 95°C for 1.2h to obtain a cryolite slurry, which was filtered and washed with a disc vacuum filter, and dried by air flow at 140°C to obtain a cryolite product 3.4kg.

Embodiment 2

[0010] Take 16kg of aluminum electrolysis waste residue, wet or dry grind it to below 150 mesh, after removing carbon and iron, put the treated waste residue into the reactor, add 12kg of concentrated sulfuric acid, start stirring and react at 60°C for 90min, the reaction The generated hydrogen fluoride gas was absorbed with NaOH solution, and 60 kg of water was added to the waste residue after acid hydrolysis, stirred for 5 minutes, and the residue was removed by filtration. The filtrate was put into the reactor, and 20% Na was slowly added under stirring condition. 2 CO 3 4.2kg of solution and 5.5kg of 40% hydrofluoric acid were reacted at a reaction temperature of 80°C for 2 hours to obtain a cryolite slurry, which was filtered and washed by a disc vacuum filter, and dried by air flow at 160°C to obtain a cryolite product 4.0kg.

Embodiment 3

[0012] Take 16kg of aluminum electrolysis waste residue, wet or dry grind it to below 200 mesh, after removing carbon and iron, put the treated waste residue into the reactor, add 15kg of concentrated sulfuric acid, start stirring and react at 80°C for 60min, the reaction The hydrogen fluoride gas produced is Na 2 CO 3 After absorbing the solution, add 100kg of water to the waste residue after acid hydrolysis, stir for 10 minutes, and filter to remove the residue. The filtrate was put into the reactor, and 20% Na was slowly added under stirring condition. 2 CO 3 4.6kg of solution and 6kg of 40% hydrofluoric acid were reacted at a reaction temperature of 50°C for 2.5h to obtain cryolite slurry, which was centrifugally filtered and washed by a centrifuge, and dried in a rotary kiln at 200°C to obtain cryolite product 4.4 kg.

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Abstract

The present invention provides a method of cryolite by aluminum electrolysis waste residue, aluminium electrolysis waste residue is milled below 60-200 mesh, removing carbon, iron in waste residue, adding concentrated sulphuric acid, reacting 30-180 min under the temperature 20-90 Celsius, the prepared Hydrogen fluoride gas is absorbed by water or lye. Adding 1-20 times water of waste quality after completing, mixing 2-20 min, filtering, adding 10%-30% sodium carbonate solution or solid sodium carbonate, 10%-50% hydrofluoric acid in filtering liquid. Under the mixing condition, ice crystal stone slurry is obtained by reaction 1-3 hours under the temperature 20-95 Celsius, ice crystal stone product is obtained by filtering, washing, drying. The invention can utilize waste slag generated in aluminium electrolysis course, and has lower cost, hydrogen fluoride gas generated in the waste treating process produces ice crystal stone product for recycling use after being absorbed by water or lye.

Description

technical field [0001] The invention belongs to a method for preparing cryolite, in particular to a method for producing cryolite by utilizing aluminum electrolysis waste residue. Background technique [0002] Cryolite is an indispensable flux in aluminum smelting. It can also be used as a pesticide for crops, an opalescent agent for enamel, a sunscreen and flux for glass and enamel production, and wear-resistant for resin rubber. It can also be used for aluminum alloys, Electrolyte for ferroalloy and ebullient steel, ingredients for grinding wheel, etc. At present, the domestic production methods of artificial cryolite mainly include hydrofluoric acid method: dry method and wet method. Generated by high temperature reaction. The wet method is made by reacting 40-60% hydrofluoric acid with aluminum hydroxide and then adding soda ash. Fluosilicic acid method: It can be divided into ammonium fluoride intermediate product and sodium fluorosilicate intermediate product method...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/54
Inventor 邱运仁
Owner CENT SOUTH UNIV
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