CHLORIDE HYDROMETALLURGY

In hydrometallurgy, chloride solutions may be used instead of sulfate solutions. Due to complexation by chloride ions, most metals of interest in non-ferrous metallurgy are highly soluble in water. Potential series are different from the standard ones. Electrochemical reactions are highly reversible. The structure of metal deposits are worse for normal or intermediate metals but better for inert metals in chloride than in sulfate solutions. Solutions are highly conductive. Leaching of sulfides usually occurs more easily in chloride than in sulfate solutions. Regeneration of the leaching power can be achieved by oxidation or by pyrohydrolysis. Solvent extraction is a very powerful tool for purification of solutions. A number of processes have been proposed in chloride hydrometallurgy. So far, with one exception, only processes based on intermediate metallurgical products are still in operation. Recycling metallurgy and precious metals recovery will probably be developed next, followed later by complex sulfide concentrates processing.