From abstract: This U.S. Bureau of Mines (USBM) research simplified an earlier hydrogen chloride (HCl) leachsparge process developed by the USBM to recover reduction-grade alumina from domestic kaolin clay. Improvements were made by decreasing the initial leaching acid concentration from 25 to 20 pct, decreasing the leaching time from 1 to 2 h to 15 to 30 min, eliminating the solvent extraction step for Fe removal, and eliminating the step to recover the Al content of the bleedstream circuit. A 10-cycle bench-scale experiment of the simplified process showed that the ferric chloride (FeC 3) concentration built up to 9.3 g/L in the recycle stream. This did not interfere with any of the unit operations or final alumina product purity because Fe forms stable soluble chloride complexes when sparged with HC and is easily washed from the large aluminum chloride hexahydrate (ACH) crystals. The reduced leaching time and acid concentration did not decrease Al extraction.