Resourceful treatment method for fluorine-containing waste generated by aluminum electrolysis and aluminum fluoride product

Abstract

The invention discloses a resourceful treatment method for fluorine-containing waste generated by aluminum electrolysis and an aluminum fluoride product. An aluminum chloride solution is used for leaching waste electrolyte, an electrolysis device is used for electrolyzing a leaching solution according to the characteristic that the leaching solution contains chloride ions, and hydroxyl radicals are continuously separated out by a cathode, so that aluminum hydroxyfluoride precipitate and a filtrate are obtained; the obtained aluminum hydroxyfluoride can be converted into high-purity aluminum fluoride by the aid of a wet method or ( / and) dry method treatment process; the obtained filtrate is continuously electrolyzed to adjust the PH value, aluminum, fluorine and calcium ions in the solution are removed in a precipitation manner, the obtained filtrate is evaporated and concentrated, and then sodium carbonate is added to precipitate lithium. According to the method, valuable Al, F and Li in the fluorine-containing waste are converted into aluminum fluoride and lithium carbonate products respectively, the obtained aluminum fluoride is high in purity and can be used as an electrolytic aluminum additive, electrolytic aluminum circular economy is achieved, and sustainable development of the aluminum electrolysis process is facilitated.

Description

technical field [0001] The invention relates to a resource treatment method of fluorine-containing waste produced by aluminum electrolysis and an aluminum fluoride product, belonging to the field of metallurgical solid waste treatment. Background technique [0002] During the production of electrolytic aluminum, since the Na, Li, and K elements contained in the alumina raw materials are enriched in the electrolytic cell all the year round, the molecular ratio of the electrolyte will gradually increase. In order to stabilize the molecular ratio of the electrolyte system and make the electrolysis process stable, it is necessary Join AlF regularly 3 To adjust the molecular ratio; while the electrolyte capacity of each electrolyzer is fixed, adding AlF 3 At the same time, it is necessary to periodically remove part of the electrolyte from the electrolyzer. These excess electrolytes used to be consumed by filling furnaces through capacity expansion, but at present, my country's...

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Problems solved by technology

The method realizes the conversion of spent electrolytes into AlF 3 target, but the AlF obtained by the reaction of aluminum hydroxyfluoride with hydrofluoric acid 3 It has the characteristic of maintaining high concentration supersaturation (several hours at 200g / L), resulting in the AlF obtained by reacting at 20-40°C for 1-1.5h provided by the patent 3 The amount of precipitation is small, and the obtained is β-AlF 3 ·3H 2 O, cannot be directly applied to aluminum electrolysis production

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