The behaviour of carbonaceous matter in cyanide leaching of gold

The current work shows that the carbonaceous coating had a significant detrimental effect on gold dissolution when gold was pre-ground with the carbonaceous ore. Sulphide coating on gold surfaces appeared to hinder gold dissolution to a lesser extent. The dissolution of gold foils artificially coated with the natural carbonaceous matter extracted from Stawell ore was also substantially retarded. In comparison, graphite had a much lower coating ability on gold. The addition of free carbonaceous matter to pre-ground non-carbonaceous sulphide gold ores did not have much effect on gold cyanidation. However, the carbonaceous matter ground with the non-carbonaceous sulphide ores significantly reduced gold leaching kinetics and recoveries.