Alumina miniplant operations-separation of aluminum chloride liquor from leach residue by horizontal belt filtration.
Sorensen-RT; Sawyer-DL Jr.
Boulder City, NV: U.S. Department of the Interior, Bureau of Mines, RI 8831, 1983 Dec; :1-44
The Bureau of Mines has investigated the recovery of alumina by hydrochloric acid leaching of calcined kaolinitic clay. Bench-scale studies indicated that horizontal belt filtration was a practical method for separating the siliceous residue from aluminum chloride liquor generated in the leaching step. Mini-plant-scale continuous testing was performed to evaluate the filter circuits and to compare filtration response of different calcined kaolin feed materials and of different agitator-baffle designs in the leaching reactors. Soluble alumina recovery with a single filter ranged from 94 pct with minus 10-mesh feed to more than 96 pct with minus 35-mesh or misted feed. Process advantages were confirmed for the calcined misted kaolin feed material prepared by a Bureau-developed misting process. With two filters in series, an overall filtration rate of 100 lb solids/hr.Ft-2 of filter area was attained with a soluble alumina recovery of more than 99 pct. More than 99.5 pct alumina recovery was obtained with a thickener and a two-filter circuit for either the minus 35-mesh or the misted feed. Modifications in leaching reactor design made to decrease particle-to-particle attrition were successful and significantly increased filtration rates and decreased flocculant requirements.
Aluminum oxide; Materials recovery; Filtration; Leaching; Clays; Chemical reactors; Revisions; Performance evaluation; Design criteria; Flocculants
IH; Report of Investigations
NTIS Accession No.
Boulder City, NV: U.S. Department of the Interior, Bureau of Mines, RI 8831