ABSTRACT
Arsenic is one of the contaminants of concern frequently found in wastes from base metals (e.g. copper), uranium and gold mining and metallurgy. Waste rock generated during mining, tailings from mineral processing and metallurgy, exposed material in the final pit are examples of As sources. In these cases, the main arsenic-bearing minerals are arsenopyrite (FeAsS), arsenian pyrite (Fe(As,S)2, scorodite (FeAsO4.2H2O), amorphous or crystalline ferric arsenates (Nordstrom, 2012). Arsenopyrite is typically found in the final mine pit, in the flotation and hydrometallurgical tailings, and in waste rock material. Scorodite is found in the wastes and tailings of weathered orebody; it is a product of the hydrothermal oxidation of sulfides, for instance, in the pretreatment of refractory gold ores. In regions of former artisanal mining, arsenic is usually found as co-precipitates or adsorbed on the sediments.
