Optimisation of metal extraction from chromium ore processing residue in New Jersey, USA

The feasibility of extracting metals from chromium (Cr) ore processing residue (COPR) was investigated. COPR samples collected from four sites in New Jersey, USA (sites A, B, C and D) were mixed with 15% carbon by weight with different percentages of sand to neutralise the basic oxide in COPR and heated under a reducing environment to extract metals. At 15% and higher sand additions, a pool of melted metal was formed underneath the slag for some test batches. In this research, knowing the chemical composition of COPR and the depth of melt, the chemical engineering tools of phase and viscosity diagrams were used to compute the type and amounts of additives needed to optimise and compute the temperature and duration of melt to achieve maximum metal separations. With optimisation, as much as 30% by weight of metal was extracted from the initial mass of COPR collected from sites C and D when those melting mixtures contained 20% or more sand by weight. On average, the metal phase contained ∼90% of combined amounts of iron (Fe), chromium and titanium (Ti).