1. Cyanide Consumption in Dissolving Gold. The cyanidation plants has been using sodium cyanide to dissolve the gold from the ore in order to recover the gold from the leaching solution. The formula is as follows: 2Au+4NaCN+O2+2H2O2Na Au 2+2NaOH+H2O2. 2Au+4NaCN+H2O22Na Au 2+2NaOH. From the electrochemical reaction, it can be ...
The best gold extractions and lowest cyanide consumption were reached when no ferrocyanide was found in the solution after 6 hr. In the presence of the optimum lead concentration, a starting pH of about 9.6 using about 2 lb. lime per ton, in the presence of suitable buffers, gave the best results.
The consumption of cyanide during processing operations is a major economic cost in the extraction of gold from its ores, while the discharge of cyanide wastes may result in significant environmental pollution. Many factors influence the levels of consumption and discharge of cyanide, including ore mineralogy and lixiviant solution chemistry.
Because cyanide leaching is very efficient, it allows profitable mining of much lower ore grades. Mining lower grade ore requires the extraction and processing of much more ore to get the same amount of gold. Partially due to cyanide, modern mines are. much larger than before cyanide was used;