Phase change of chlorite in reducing atmosphere

Magnetizing roasting is an important pre-treatment technique for beneficiation of hematite and limonite ores. Reduction mechanisms of these iron minerals have been fully studied while the mechanism of reduction of chlorite is not well understood. In this study, a reduction roasting study examining the phase change of chlorite with roasting temperature was undertaken. The major finding from this study was that chlorite partially was reduced to magnetite by carbon at 750 ⁰C, and the newly formed magnetite was finely disseminated within quartz and olivine. It was demonstrated that these locked magnetite particles would be reported to iron concentrate by low intensity magnetic separation resulting in high impurity content, especially SiO2 and Al2O3 contents in the concentrate.