Treatment of chromium-containing sludge using sintering and ironmaking combined technology: A risk-reducing strategy for environmental impact

The efficient, safe and eco-friendly disposal of the chromium-containing sludge (CCS) has attracted an increasing concern. In this study, Co-processing of CCS was developed via employing sintering and ironmaking combined technology for its harmless disposal and resource utilization. Crystalline phase and valence state transformation of chromium (Cr), technical feasibility assessment, leaching risk, characteristics of sintered products, and pollutant release during CCS co-processing were investigated through a series of laboratory-scale sintering pot experiments and large scale industrial trials. The results showed that the content of Cr(VI) in sintered products first increased then decreased with increasing temperature ranges of 300 °C-800 °C, and reached a maximum of 2189.64 mg/kg at 500 °C. 99.99% of Cr(VI) can be reduced to Cr(III) at above 1000 °C, which was attributed to the transformation of the Cr(VI)-containing crystalline phases (such as, MgCrO