USE OF HYDROGEN FOR IRON RECOVERY FROM BAUXITE RESIDUE (BR)

Abstract

Using direct hydrogen reduction in a rotary kiln without smelting and the dissolving of solid residues under high pressure in an autoclave, this study investigates pyrometallurgical and hydrometallurgical techniques for decarbonizing and recovering precious metals from bauxite residue. The aim of this paper is to provide decarbonizing methods for removing iron from bauxite residue, a Bayer process by-product that cannot be disposed of in an environmentally responsible way. Hydrogen is being researched as a cleaner substitute for conventional carbon-based reductive melting, which produced large CO₂ emissions. A rotary kiln's hydrogen reduction process recovers 99.9% of the iron as iron, which can then be separated from the solid residue that contains other valuable metals using magnetic separation. In contrast to very stable oxides like titanium oxide, silica, and aluminum oxide, we found that hydrogen can reduce iron oxide from bauxite residues to metallic iron. Sulfuric acid leaching of titanium, iron, and aluminum is highly effective when done in an autoclave at high pressure.