GRANULATED BATCH FOR ELECTROLYTIC PRODUCTION OF ALUMINIUM (VERSIONS) AND A METHOD OF PREPARATION THEREOF Russian patent published in 1997 - IPC

FIELD: aluminium production. SUBSTANCE: to correct composition of electrolyte in a known batch containing calcium fluoride and mixture of sodium and aluminium fluorides and/or their compounds, in the batch, according to invention, NaF/AlF₃ ratio does not exceed 0.86 and calcium fluoride content is 0.1 to 30.0%. According to another version, to maintain electrolyte level in granulated batch, NaF/AlF₃ ratio should be 0.85-1.60 and calcium fluoride content should be 0.1 to 20.0%. In a method of preparing granulated batch to introduce into electrolyte of aluminium electrolyzer including mixing fluoride salts, crushing, wetting, granulation, and drying, distinguishing feature is using aluminium and/or sodium fluorides and/or cryolite, which are mixed in presence of calcium fluoride, the salts being crushed to obtain fraction up to 8 mcm in amount at least 10%. EFFECT: reduced loss of granulated fluoride salts under aluminium electrolysis because of increased rate of dissolution of granules. 3 cl, 1 tbl