Speciation and reduction potentials of metal ions in concentrated chloride and sulfate solutions relevant to processing base metal sulfides

The speciation, Eh-pH and Eh-log a_Cl- dependence of Fe(III), Fe(II), Cu(II), Cu(I), Ag(I), Pb(II), Zn(II), Ni(II), As(III), Sb(III), and Bi(III) ions in practical (high ionic strength) sulfate and chloride solutions are discussed. The emphasis is placed on those ions which form strong sulfato-, chloro-, and hydroxo-complex species. Measured potentials are compared with potentials calculated from reported association and stability constants to test the applicability of these constants in nonideal solutions and to characterize predominant species. Formerly Postgraduate Student, Murdoch University, Perth, Western Australia