Reduction of metals from sulfides

Existing notions on reduction of metals from oxides and sulfides are based on realization of dissociative processes associated with the formation of simple substances. Metal sulfides can be considered as compounds of oppositely charged species formed owing to totality of electrostatic and coordination binding in the Mez+-S2- system. Reduction of metals from such compounds with the use of donor properties of sulfide sulfur is an electrochemical process with the participation of the electrode pair Mez+ and S2- in the mode of internal electrolysis in the system, which provides utilization of elemental sulfur that is formed through chemical reactions. As an electrochemical medium, molten caustic soda is proposed. In its presence, elemental sulfur dispro- portionates with the preferential accumulation of sulfide and sulfate sulfur. The reaction causes irreversibility of the reduction process. © Allerton Press, Inc., 2007.