Characterization and mobilization of toxic metals from electrolytic zinc waste

The natural and forced mobilization of lead, cadmium and arsenic in zinc hydrometallurgy waste is studied with the purpose of establishing potentially environmentally damaging levels and associated risks in uncontrolled situations. Differential X-Ray diffraction is used to study, in simulated environmental situations, the relevant role played by several mineralogical and amorphous phases. The study of potential mobility shows that all the samples considered are susceptible of releasing a significant amount of potentially toxic elements (PTEs) depending of the particular environmental conditions. Two situations can be considered the most problematic: the natural mobilization of the released cadmium and zinc as a result of rain, and a change in the redox conditions caused by an anoxic environment (flooding and/or incorporation of organic matter). The presence of massive quantities of soluble salts increases the hazard potential of these residues, mobilizing the PTEs and creating a potential carcinogenic risk caused by a possible oral intake for both children and adults.