Aluminum Chloride Leaching and Hydrolytic Disproportionation to Produce Alumina from Kaolin.
Metallurgical Society Inc 1988 :825-832.
In the work described in this paper, the Bureau of Mines extracted aluminum from calcined kaolin with aluminum chloride solution or substoichiometric amounts of hydrochloric acid. The leaching method produced solutions containing basic aluminum chloride salts, which require less energy for decomposition to alumina than the aluminum chloride hexahydrate (ach) produced in the Bureau of Mines clay-hcl process. Hydrolytic disproportionation at elevated temperature and pressure of the basic aluminum chloride solution produced hydrated aluminum oxide with very low chloride content and an aluminum chloride solution for recycle to leaching. Simulated two-stage counter-current leaching and the hydrolytic disproportionation of the resulting basic aluminum chloride solution were integrated. Buildup of silica and iron in solution and coprecipitation during disproportionation prevented recovery of a cell-grade alumina product; and aluminum recovery, under the conditions tested, was not adequate to achieve complete aluminum chloride leachant regeneration.
Metallurgical Society, Inc., 1988, PP. 825-832.