Sulfur Dioxide – A Leachant for Oxidic Materials in Aqueous and Non-aqueous Media

Abstract

Leaching of various oxide materials using sulfur dioxide is documented in this review. Emphasis is given to the leaching of Fe(III), Mn(IV), Mn(III) oxides/hydroxides highlighting the mechanisms and kinetics of these systems. Treatment of magnesium oxide associated with serpentinic silicate tailings, copper–zinc containing silicate slags, nickel containing waste catalysts, roasted zinc sulfide concentrate and aqueous reduction of As(V) to As(III) are included. Acetone and aqueous SO₂ mixtures form α-hydroxy sulfonic acid, which is useful for leaching phosphate and uranium ores. Aspects related to leaching of some oxidic materials in organic solvents such as dimethyl sulfoxide (DMSO), dimethyl formamide (DMF) and acetonitrile in the presence of sulfur dioxide are also considered, since novel reactions in non-aqueous solvents may open up new opportunities for the treatment of complex materials.

Keywords::

• Sulfur dioxide
• oxidic material
• leaching
• aqueous
• non-aqueous