Fe(II)-induced transformation of Jarosite residues generated from zinc hydrometallurgy: Influence on metals behaviors during acid washing

Abstract

As hazardous materials, jarosite residues pose severe challenge to the environment due to the presence of coexistent metals. Although acid washing conducted in the industrial process could recover acid extractable metals, a significant amount of strongly surface-bound, entrapped, and lattice-incorporated metals in jarosite residues could not be extracted easily. Fe(II) has received increasing attention for its effect on triggering the release of elements, as well as the transformation of Fe minerals. This study, for the first time, aims to simulate acid washing to assess the acid extractable metals (Zn, Pb, and Cu) in an actual jarosite residue with and without Fe(II)-induced transformation. Metals (i.e., Zn, Pb, and Cu) showed enhanced acid extractability in the process of 2nd acid washing after Fe(II)-induced natrojarosite transformation to goethite, especially for Pb and Cu, the highest concentrations of which were 17 and 7-time as much as those before the transformation, respectively. In addition, it has been found that metals have different behaviors during Fe(II)-induced transformation and acid washing, possibly due to their different speciation in jarosite residue. This room-temperature and impurity-free strategy of Fe(II)-induced transformation has the potential for jarosite residues treatment and metal recovery.