Metal extraction from chromium contaminated soils

The feasibility of separating metal from chromium contaminated soils was investigated. Soil samples were mixed with 15% by weight of carbon as a reducing agent and different percentages of sand to neutralize the basic oxides in soils as the metal separation was observed only when sand was added. At 15% sand content and higher, a pool of melted metal was formed underneath the slag for some tests. As much as 30% by weight of metal was extracted from the initial mass of soils collected from two sites when their mixtures contained 20% by weight of sand. At this composition, the least dissolution of metal in the oxide phase was also reported. The composition of metal depend on original composition of the soil. On average the metal phase contained ~ 90% of Fe, Cr, and Ti combined. Readily available tools such as phase and viscosity diagrams, were also used to predict the behavior of the compositions upon melting. They proved to facilitate selecting proper mix compositions to achieve optimum metal separation.