Treatment method of waste industrial lithium-containing aluminum electrolyte

Abstract

The invention relates to a treatment method of a waste industrial lithium-containing aluminum electrolyte. The method comprises the following steps that fine powder of the waste industrial lithium-containing aluminum electrolyte is mixed with a first reactant, and roasting is carried out to obtain a roasted material; after water leaching, filtrate A and filter residues A are obtained; the pH value of the filtrate A is adjusted to 6-10 to obtain a cryolite product; a second acid solution is mixed with the filter residues A, and after reaction, filtrate C and filter residues C are obtained; the pH value of the filtrate C is adjusted to 6-8 to obtain a hydroxy aluminum fluoride product and filtrate C '; and carbonate is added into the filtrate C ', and after reaction, a lithium carbonate product is obtained. The method is different from the traditional method of leaching the waste aluminum electrolyte with strong acid, the lithium-sodium composite cryolite in the electrolyte is converted into LiAl<2> (OH) <7> by adopting an alkali-adding roasting treatment mode, the lithium element is simply and conveniently separated from other impurity phases, the lithium recovery rate is high, and the byproduct regenerated cryolite can be returned to an aluminum electrolysis cell for use, the utilization rate of other valuable elements is further improved, and a new method is provided for recycling the lithium-containing aluminum electrolyte.

Description

technical field [0001] The invention relates to a treatment method for waste industrial lithium-containing aluminum electrolyte, belonging to the field of metallurgical solid waste treatment. Background technique [0002] In recent years, with the rapid development of the metallurgical industry, the production capacity of electrolytic aluminum has reached the "ceiling". High-grade bauxite resources can no longer fully meet production needs, and more and more low-grade bauxite is being mined and utilized. Lithium content in low-grade bauxite is high (Li 2 O mass fraction is 0.016% ~ 0.030%), during the Bayer stripping process, about 80% of the lithium in the bauxite will enter the sodium aluminate solution, which will lead to an excessively high lithium content in the calcined alumina product . In the subsequent aluminum electrolysis process, lithium will be enriched in the electrolyte system, resulting in an increase in the lithium content in the electrolyte. The mass frac...

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Problems solved by technology

[0005] In view of the problems that other impurity elements will be leached together by strong acid leaching electrolyte, corrosive gas will be generated and the purity of lithium salt obtained is low, the Chinese invention patent specification CN11291507A proposes to use lye to leaching electrolyte multiple times to convert lithium element into LiF precipitation, after acid leaching LiF is precipitated and transformed into soluble lithium salt, and then the pH is adjusted to 10-12 to obtain an alkaline mixed solution, and then carbon dioxide is introduced to precipitate lithium. Although this method reduces the emission of toxic gases and produces valuable cryolite by-products, it is Three times of alkali leaching in the front-end treatment not only consumes a large amount of alkali, but LiF will be partially dissolved into the sodium aluminate solution during the multiple alkali treatments, which increases the loss of lithium to a certain extent, and also increases the amount of filter residue produced Invisibly, more acid will be consumed, and the processing cost will increase significantly

In addition, the Chinese invention patent specification CN110284157A discloses a method of mixing and roasting anode carbon slag and aluminum electrolyte with calcium-containing substances and alkali-containing substances, and the roasted products are subjected to alkali leaching to obtain calcium fluoride and sodium aluminate solutions and return them to the Bayer process for alumina production. Although the method is simple in process, calcium salt is added to fix fluorine during the treatment process, which leads to low utilization rate of valuable fluorine

[0006] In summary, the current mainstream process for extracting lithium from lithium-rich aluminum electrolytes is still a wet process, and strong acid leaching is commonly used, which brings great challenges to equipment and operating environments. Therefore, it is necessary to seek cleaner and more efficient lithium extraction. craft

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