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The combination of HCl-based dry digestion of bauxite residue and multi-stage circulation of the leach liquor was studied. The proposed processing technology allows to achieve a high selectivity for rare-earth elements with a limited co-dissolution of silica (< 5 wt%). The scandium concentration increased from 7 mg L-1 in stage 1 to 19 mg L-1 in stage 5, while the concentration of yttrium, lanthanum and neodymium increased from an average value of 7 mg L-1 in stage 1 to an average of 18 mg L-1 in stage 5, more than twice the concentration observed for single-stage leaching after dry digestion, and four times higher than the concentration achieved by a conventional direct acid leaching method. The water consumption was reduced by 60% in comparison to the conventional direct acid leaching method. ispartof: pages:433-439 ispartof: Proceedings of the 2nd International Bauxite Residue Valorisation and Best Practices Conference, Athens (Greece), 7-10 May 2018 pages:433-439 ispartof: 2nd International Bauxite Residue Valorisation and Best Practices Conference location:Athens (Greece) date:7 May - 10 May 2018 status: published |
