PRODUCTION OF ALUMINA FROM ORES

摘要

PRODUCTION OF ALUMINA FROM ORES An aluminum-containing ore such as a kaolin or montmorillonite clay is treated with a fluorine acid such as HF or H2SiF6 to produce aluminum fluoride (AlF3) which is recovered from the liquid phase of the reaction mixture by crystallization as AlF3 . 3H2) crystals which are then dried and dehydrated to yield AlF3. The crystallization mother liquor is recycled to the process to recover its AlF3 values. The AlF3 . 3H2O crystals and separated solid phase of the reaction mixture are washed to recover AlF3 values and the wash streams recycled to the process. To produce alumina, the AlF3 is pyrohydrolyzed to Al2O3 and HF. The HF is absorbed in the crystallization mother liquor and recycled with the mother liquor to the ore treatment step. All or a part of fluorine acid requirements can also be supplied from any suitable source such as, for example, a wet process phosphoric acid facility which is a plentiful source of inexpensive sluorine. The fluorine acid requirements can be supplied in a recycle stream of the process such as the crystallization mother liquor and/or a fresh make-up stream. The process converts the aluminum values in aluminum-containing ore deposits to a form (Al2O3) useful in the production of aluminum metal.