Bioleaching of Scandium from Bauxite Residue using Fungus Aspergillus Niger

Abstract Bauxite residue (BR) is the main by-product of alkaline production alumina from bauxite containing significant amounts valuable metals such as scandium that belongs to rare-earth elements (REEs), classified by European Community critical raw materials (CRMs). BR considered a hazardous waste due its huge volume and high alkalinity making disposal serious universal environmental problem. The recovery Greek can be an excellent approach for management resource efficiency using environmentally friendly biometallurgical methods. In this work, bioleaching fungus Aspergillus niger was studied. Bioleaching experiments were performed Taguchi experimental design, in batch cultures with at various pulp densities (1, 5 10%, w/v), sucrose concentrations (40, 90 140 g/L) suspension 2, 4, 6% v/v under one-step condition subculturing. highest Sc equal 46%, achieved 20 days 1% density. Biosorption phenomena observed during leaching process. Lactic, acetic, oxalic citric organic acids identified. Graphical