Leaching Study of Guinean Bauxite Tailings in aqueous HCl Solution for the Extraction of Aluminum

Abstract

Primary aluminum production is dependent on the Bayer process for Al2O3 refining and the Hall–Héroult process for Al production. Both these processes face serious sustainability challenges, while the overall Al supply chain is inflexible and prone to disruptions. One solution to the aforementioned challenges is the adoption of alternative Al2O3 production processes from a variety of primary and secondary raw materials. This research paper explores the potential use of bauxite tailings as an alternative secondary resource for alumina production, with an aqueous HCl process technology. Bauxite tailings are solid waste produced during the mining and beneficiation of certain bauxites before their digestion in the Bayer process. The research was conducted in two stages. Initially, 24 h trials using aqueous 5.9 M HCl solution and a 5:100 g/mL solid-to-liquid (S/L) ratio revealed complete dissolution of Al and near-complete dissolution of Fe. In the second stage, investigations involving higher S/L ratios under the same conditions confirmed that an S/L ratio of 20:100 g/mL represented the optimal parameters for bauxite tailings leaching, producing a 36.8 g/L Al and 25.2 g/L Fe concentration solutions. The PLS produced under the optimum conditions is suitable for downstream processing for the production of AlCl3·6H2O.