Method for transforming a crystal form of an electrolyte containing lithium for aluminum electrolysis

A method for transforming a crystal form of an electrolyte containing lithium for an aluminum electrolysis, comprising the following steps:

• S1, pulverizing the electrolyte containing lithium to obtain an electrolyte powder;
• S2, uniformly mixing an additive with the electrolyte powder to obtain a mixture, wherein the additive comprises an oxo acid salt of an alkali metal excluding lithium;
• the oxo acid salt of the alkali metal excluding lithium is converted into an alkali metal oxide under a high-temperature calcination condition;
• the additive is mixed with the electrolyte powder according to a type of the additive, a first molar ratio of NaF to AlF3 in the electrolyte powder, and a lithium salt content in the electrolyte powder, a second molar ratio of a sum of a first alkali metal fluoride, a second alkali metal fluoride, and a third alkali metal fluoride in the mixture to aluminum fluoride is greater than 3;
• wherein the first alkali metal fluoride is contained in the electrolyte powder, the second alkali metal fluoride is added by the additive, and the additive is converted to the third alkali metal fluoride under the high-temperature calcination condition;
• and
• S3, briquetting the mixture, and calcining the mixture at 300° C.-1200° C. for 1 hour-5 hours;
• wherein during a calcination process, an insoluble lithium salt in the electrolyte powder is converted into a soluble lithium salt;
• wherein, in step S2, the oxo acid salt of the alkali metal excluding lithium is at least one selected from the group consisting of Na2SO4, Na2CO3, Na2C2O4, NaNO3, CH3COONa, K2SO4, K2CO3, K2C2O4, KNO3, and CH3COOK.