The most generally employed method for gold recovery from ores is cyanide technique by means of which more than 70% metal are produced. The technique is based on treatment of ores by aqueous solution of NaCN or other organic cyanides in the presence of oXy￡en. The process proceeds in accordance with the following expression: 4Au + 8NaCN + 2H2O + O2 => 4NaAu(CN)2 + 4NaOH With allowance for cheapness of all reagents including water as solvent, the cyanide method has essential drawbacks - low selectivity of the process. Along with gold and silver the considerable amounts of copper, zinc, iron cobalt manganese other accompanying elements are recovered on treatment of initial ore. osses of noble metals due to separation of leached ore from process solutions; necessity for concentrating of process solutions; low process effectiveness on treatment of strong ores; high toxicity of cyanide compounds Non-cyanidable forms of gold in ores of different origin represent a metal covered by dense thin layer of iron hydroxide films and disseminations into rock-forming minerals Therefore, additional expenses are required for special protection measures, control over content of hazardous components and the environmental protection concerned with treatment of cyanide-containing waste. The trend universally adopted in industry and directed to more severe requirements imposed on the ecological safety increases production costs of enrichment facilities, adds to risk of penal sanctions and thus decreases profitability of ore tieatment by cyanide process. So, in the last ten years the investigations are underway on searching some new reagents as cyanide substituents and on developing the systems to leach noble metals from ores.
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