Dissolution of Iron Oxide Rust Materials using Oxalic Acid.

Abstract

The dissolution of iron oxides is an important hydrometallurgical process if it can be applied to industry. Some of the potential applications include cleaning of iron surface and removal of iron oxide from industrial minerals. In this study, the dissolution of hematite obtained from iron ores using oxalic acid was evaluated at different initial pHs, acid concentration and temperature. It was found that the dissolution of iron oxide rust was very slow at temperatures ranging from 25°C to 60°C, but increased rapidly as temperature became above 90°C. An increase in concentration of oxalic acid in the range of 0.048～0.476mol/l increased the dissolution rate, whereas the pH caused some passivation (at pH > 2.5) after improving the rate from pH 1 to pH 2.5. When the technique was applied to dissolving of the iron oxide rust, it was found that the iron oxides existing in the rust, which are mainly goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and iron hydroxide (Fe(OH)3) can be dissolved faster than with hematite.