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A Basic Chloride Method for Extracting Aluminum from Clay.
Bremner-PR; Nicks-LJ; Bauer-DJ
MISSING :8 pages
As part of a program to devise alternative technologies for producing alumina from domestic resources, the Bureau of Mines investigated the leaching of calcined kaolinitic clay to form basic aluminum chloride solutions. Bench-scale experiments were conducted for single-stage batch leaching with alcl3 solution and three-stage countercurrent leaching with substoichiometric hcl. Variable conditions of clay calcination and leaching were studied to determine their effects on aluminum extraction and pregnant liquor composition. With clay calcined at the best temperature of 850 deg c, extraction of more than 93 pct of the aluminum was achieved. The basic chloride pregnant liquors were crystallized and yielded the compound 5alcl3.8Al(oh)3.37.5H2o, which can be thermally decomposed to alumina with 61.6 pct of the energy required for decomposition of alcl3.6H2o. In comparison with the leaching operation in an hcl- clay process, the basic chloride system offers substantial advantages in energy consumption and equipment size requirements.
IH; Report of Investigations