Hydrometallurgical technologies of processing arsenic raw materials

Abstract

Methods presented in Russian and foreign scientific literature sources for processing high-arsenic copper raw materials to convert arsenic into low-soluble and stable compounds are reviewed. Hydrometallurgical processing methods are shown to be applicable for converting environmentally hazardous components into inert solid wastes while avoiding the formation of gaseous emissions. The isolation of arsenic when processing raw materials involves its oxidation and precipitation in the form of low-soluble and stable compounds. Methods for arsenic oxidation using oxygen, hydrogen peroxide, ozone, mixture of oxygen and sulphur dioxide, sodium hypochlorite are compared. Methods of oxidation by iron and permanganate ions, bacteria (biooxidation), as well as by introducing an activated carbon catalyst, are also considered. Precipitation approaches include neutralization by lime, precipitation of sulphides, co-precipitation of arsenic with iron ions, precipitation of scorodite, and encapsulation technology. As a result of the performed analysis, the authors present a promising approach for solving the problem of processing high-arsenic copper concentrates to comply with standards governing arsenic emissions into the environment, including the comprehensive processing of these raw materials using autoclave oxidation. In addition to the ensuring effective precipitation of arsenic in the form of a low-toxic compound (scorodite), this method can be used to isolate valuable components (copper, gold, silver) with their subsequent extraction into individual finished products. The obtained results establish a direction for a further in-depth study of the problem.