ABSTRACT
In a leaching process, regeneration of the chrome, which is a costly reagent, is essential. This chapter provides an account of various leaching processes. They are cyanide leaching, chlorine leaching, hypochlorite leaching, hypochlorous acid leaching, dichromate leaching, and electrochemical leaching. As in the case of any other leaching processes, the success of cyanide leaching of gold and silver ores depends on the nature of the ore and, of course, on the leaching of parameters such as solution pH, cyanide concentration, and temperature. The most popular and accepted method of recovering cyanide ions is the oxidation of the solution with agents like O2, O3, Cl2, H2O2, permanganate, and cupric ions. Cyanidation is taken as an efficient and economic method for silver recovery. There are silver ores which contain rather low amounts of base metals to justify the earlier-mentioned conventional treatment procedure.
