A Detailed Laboratory Scale Feasibility Study of Recovering Metallic Iron and Chromium from Chromium Contaminated Soils

One of potential technologies applicable to chromium-contaminated soils is thermal treatment, for example, the vitrification. Literature showed the reduction of hexavalent to trivalent chromium at high temperature, thus converting highly toxic and water-soluble compound into less toxic and water-insoluble compound. At high temperature, such as that of vitrification, both iron and chromium oxides can experience stepwise reduction to potentially recyclable metallic iron and chromium under reducing environment. Hence the objective of this study is to investigate the feasibility to reduce iron oxides in chromium-contaminated soils. Using solid carbon as reducing agent, the reduction to metallic iron was observable at 1200 °C. At 1400 °C, the addition of 15 % carbon by weight is required for complete reduction. The reduction is very rapid at this temperature. The information on reduction at high temperature should prove useful in providing background information in thermal treatment and also the potential recycling of metal from contaminated soils.