AIChE Journal February 2022

Abstract

The Bayer process holds an exclusive status for alumina extraction, but a massive amount of caustic “red mud” waste is generated. In this work, three oxalate reagents: potassium hydrogen oxalate (KHC₂O₄), potassium tetraoxalate (KHC₂O₄·H₂C₂O₄), and oxalic acid (H₂C₂O₄) were investigated for the Al and Fe extraction process from NIST SRM 600 Australian-Darling range bauxite ore. More than 90% of Al and Fe was extracted into the aqueous phase in less than 2 h with 0.50 M  for all three reagents. The Fe and Al can be selectively precipitated by hydrolyzing the aqueous phase. By acidifying the Al and Fe free filtrate, 80% of the  can be precipitated as KHC₂O₄·H₂C₂O₄. Greater than 90% of the aqueous acid can also be recycled using a cation-exchange resin. The proposed closed-loop process is an energy-efficient, cost-effective, environmentally–friendly route for extracting Al and Fe from bauxite ore.

Citation

Ankit Verma, David R. Corbin, and Mark B. Shiflett. “Extraction of aluminum and iron from bauxite: A unique closed-loop ore refining process utilizing oxalate chemistry." AIChE Journal, 2022, 68, 2.