The content of lithium metal in Chinese bauxite is between 0.016% and 0.03%, and the content of lithium metal in some bauxite is as high as 0.068%. High lithium alumina is generally produced in Henan, Shanxi and other provinces, and the output accounts for more than 60% of the total alumina in China. The self-supply rate of Chinese bauxite accounts for 44%. In the Bayer process of alumina production, about 80% of the metal lithium in bauxite enters into aluminum hydroxide. In the process of high temperature calcination of aluminum hydroxide, about 25% of the metal lithium is lost due to sublimation. The accumulation of lithium in aluminum electrolyte leads to the increase of lithium content in aluminum electrolyte. It is generally believed that the concentration of lithium in the range of 1 ~ 3wt% is conducive to reducing the initial crystal temperature of aluminum electrolyte, and the concentration of lithium in the range of 5wt% will affect the condition of aluminum electrolytic cell to a certain extent, while the concentration of lithium in some electrolytic aluminum enterprises even reaches 8 ~ 10wt%. In 2021, the cumulative output of alumina from January to December is 77,475,000 tons. Therefore, theoretically, the annual enriched lithium content is about 25,000 tons (lithium carbonate equivalent). The price of lithium carbonate, especially battery grade lithium carbonate, has increased from 40,000 to 50,000 yuan/ton in the first half of 2021 to 500,000 yuan/ton currently. So the extraction of lithium from cryolite has high commercial value.

The toxic substances of inorganic fluoride and cyanide in the overhaul slag of aluminum electrolysis seriously pollute the environment, but the existing disposal technology is backward and the utilization of valuable resources in the overhaul slag is not realized. The recycling technology of the overhaul slag of aluminum electrolysis and lithium extraction technology of high content cryolite can realize the product recovery of high value fluoride salt and strategic resources lithium salt. The purity of cryolite products recovered reached more than 96%, meeting the "cryolite" (GB/T 4291-2007) standard. The dissolution rate of lithium salt is above 90%, and the purity of lithium carbonate product is 98.9%. The indicators of tailings meet the requirements of "Identification Standard of Hazardous Waste Leaching Toxicity Identification", and can be used as general industrial solid waste management or resource utilization. It can be used independently or grafted in aluminum electrolysis industry line, showing the characteristics of low operation cost, high added value of products, and disposal process in accordance with the law.

Taking the electrolytic aluminum plant with annual output of 200,000 tons as an example, by making full use of this technology, it can produce 3,400 tons of electrolytes annually, annual sales revenue can reach 85 million yuan and the profit will be 42.5 million yuan (50% profit rate).

The investment is expected to be 3 million.