Alumina Miniplant Operations-Treatment of FeCl3-Loaded Stripping Liquor with Calcined Kaolin

摘要

The stripping of iron-laden solvent with hydrochloric acid in the iron-removal step of the clay-hydrochloric acid process for the extraction of alumina from calcined kaolinitic clay results in a loaded ferric chloride stripping liquor. Treatment of the stripping liquor at boiling with calcined kaolin to form insoluble Fe2O3(s) and a dilute AlCl3 solution was undertaken by the Bureau of Mines to characterize process problems and to aid in sizing of solids-liquid separation equipment. Variables identified as important in the chemical reaction were calcined kaolin particle size, ratio of calcined kaolin to FeCl3, and reaction time. The parameters were tested for significance and the interactions investigated. Fine calcine kaolin (-65 mesh) at a greater than 1:1 mole ratio of contained acid-soluble Al2O3 to Fe2O3 equivalent of the FeCl3 in the stripping liquor required less reaction time than coarser (-16 mesh) material. Solids-liquid separation of the reacted slurries by both settling and filtration requires flocculation.