Studies on the preparation of cryolite by fluoboric acid process

Abstract

Calcium fluoride, boric acid and sulphuric acid react in an aqueous medium with the formation of fluoboric acid. The reaction goes practically to completion when pure materials are used. Fluoboric acid thus formed can be utilized for the formation of cryolite and other fluorides. A cyclic process for the production of cryolite from metallurgical grade fluorspar, sulphuric acid and boric acid has been studied in this paper. The immediate product, fluoboric acid, which is formed is reacted with hydrated alumina and sodium carbonate to form cryolite while boric acid is regenerated. The spent liquor containing boric acid is cycled a number of times to get more fluoboric acid and thence cryolite. (Mr. Gurdial Singh, Scientist and Dr. B.C. Kar, Scientist, National Metallurgical Laboratory, Jamshedpur)