Bauxite Processing Via Sulfide Chemistry

Through the emergence of inert anodesInert anodes and clean electricity, greenhouse gasGreenhouse gases emissions related to aluminum electrolysisAluminum electrolysis may fall substantially. However, this shift does not mitigate sustainabilitySustainability challenges in upstream mineral processingProcessing. Today, the Bayer processBayer process for aluminaAlumina production is identified as a major contributor to ecotoxicity, fossil fuel resource depletion, and ozone depletion in the aluminumAluminum supply chain. This process also generates 2 to 3 tonnes of highly alkaline bauxite residueBauxite residue, or “red mudRed mud”, per tonne of metal produced. Significant quantities of critical elements and ironIron are also lost to red mudRed mud. Alternative approaches that improve sustainabilitySustainability and byproduct recoveryRecovery in aluminaAlumina production are clearly needed. Herein, we demonstrate a new sulfur-based process chemistry for bauxiteBauxite refining, enabling the formationFormation of distinct aluminumAluminum-rich oxide and ironIron-rich sulfide phases in the mineral matrix. These phases are predicted to be amenable to physical separation, enabling the recoveryRecovery of ironIron and other materials as sulfides that historically have been lost to red mudRed mud generation. This novel approach may leverage existing solid–gas roasting reactors and comminution/physical separation equipment.