Cost Analysis as a Tool for the Development of Sc Recovery Processes from Bauxite Residue (Red Mud)

Process development for the recovery of rare earth elements (REEs) from production wastes is generally seen as one strategy to address potential supply shortages for these critical materials. However, very few reported process systems are both technologically feasible and economically viable. Herein, we propose a strategy which considers comprehensive cost analysis in the presence of irreducible uncertainty as a core strategy introduced early on at the process design stage for the recovery of scandium (Sc) from bauxite residue (red mud). The latter represents an important process example of REE recovery from what is typically considered a waste material. In particular, using both a classical and a probabilistic framework for cost model development and assessment, cost is considered as a key design parameter in addition to selectivity and yield to design processes primed for industrial applications. We further show that such an approach affords significantly enhanced prospects of economic viability to the proposed process system when comparatively evaluated against reported ones, thus promising to drive environmental remediation of red mud through recovery of a valuable material (Sc2O3) under enhanced environmental and economic performance profiles.