Conversion of chromium ore processing residue to chrome steel

In Hudson County, New Jersey, there are more than two million tons of leftover chromite ore processing residues (COPR). Part of COPR was used as construction fill materials spreading the problem to a larger area. High solubility of some chromate compounds along with their toxicity is threatening the environment as well as human health. The primary objective of this manuscript is to demonstrate an efficient and optimum way to recover chromium and iron from COPR in the production of chrome steel or stainless steel. In this research, COPR was thermally treated to recover iron with chromium. The research applied techniques used in steel manufacturing to extract metallic iron and chromium from COPR. An extensive experimental program was performed using a Thermo-Gravimetric Analyzer (TGA) to thermally treat the processed chromium contaminated soils with additives at varying temperatures and under reducing environment. The optimum chemical composition of COPR and additives to be used in the melts was evaluated based upon the thermodynamic properties of the mixture to ensure good phase separation, least amounts of iron and chromium oxides in the slag and minimum variability of final product (steel or iron with chromium). The impact of other oxides on the steel making process was evaluated to minimize the adverse impact on the process. The research demonstrated the feasibility of the proposed process. Copyright ASCE 2008.