Strong Acid-Weak Acid Method for Producing Aluminum Chloride Hexahydrate from Kaolinitic Clay

摘要

The Bureau of Mines has conducted extensive studies on the recovery of alumina from kaolinitic clay by a HCl leaching-HCl sparging process. The current study reports a modification of the process, which involves a double-leaching system. The first leach of the calcined clay is made at as high a HCl acid strength as possible so that the dissolution of aluminum chloride hexahydrate (AlCl3:6H2O) is suppressed. Most of the impurities, but very little aluminum, are soluble in the strong acid. A proposed flowsheet is presented, and the effect of bleedstream size on AlCl3:6H2O purity is discussed.