The DSP concentrate sinter-leach process for aluminium and sodium recovery 2: leaching behaviour

ABSTRACT The novel Sandy DSP Sinter-Leach process provides a lower energy intensity method for the recovery of sodium and aluminium lost to bauxite residue. The present study is an investigation into the leaching unit of this process. Two different sinter products designed to simulate major sintering process options were leached. Leaching temperature and time were varied for both feed materials and it was found that reductive sintering yielded a product with the highest leachability under all conditions. Higher concentrations of Ca2Fe2O5 in the sinter product was linked to deleterious side reactions in leaching, which significantly reduced the aluminium recovery. A set of chemical reactions are proposed to describe the leaching step and strategies to mitigate the side reactions are discussed.