Semiconductor electrochemistry and hydrometallurgical dissolution processes

The basic concepts of semiconductor electrochemistry are reviewed. In particular, the relationship between atomic orbitals, molecular orbitals and the band model of solids is highlighted. By using the fact that redox couples in aqueous solution can also be assigned energy levels, electrochemical reactions at the solid/aqueous interface can be viewed conveniently in terms of charge transfer between energy levels. Application of these concepts to selected hydrometallurgical dissolution systems then follows, including the role of lattice substitution and nonstoichiometry in the dissolution of oxides and sulfides, the role of surface states (i.e. localized energy levels at the solid/aqueous interface) on the reduction of oxidizing agents during sulfide dissolution, and the electronic structural basis of sulfur versus sulfate formation in sulfide dissolution reactions.