Optimisation of gold recovery by selective gold flotation for copper-gold-pyrite ores

Gold flotation is often overlooked as a processing option as the precious metal is viewed as being associated with the sulphide particles present in the ore, even when a proportion of the gold is free. Gold does float readily, however, and the free gold can be selectively floated away from an ore containing sulphides. This may be an alternative treatment route for gold room applications where fine gold losses can occur when treating gravity concentrates with pyrite and copper sulphides present. Floating gold from the sulphides could produce a directly smeltable product. Copper sulphides are selectively floated from pyrite ores at high pHʹs in excess of 11. It is less clear how the free gold behaves under these conditions. In addition, for extra gold recovery, further collectors are added, such as the monothiophosphates, which are known to be selective gold collectors. What form does this additional gold recovery take? These are some of the questions left unanswered from the literature. wer some of these questions, the effect of collector type, and various operating variables, including pH, grind size and collector additions on gold flotation performance were investigated. h pH, selectivity of gold against pyrite was possible with a number of collectors. However, there was no selectivity against chalcopyrite in the flotation tests performed. Increasing the pH using lime showed no gold depression. Fine gold was easily floated while some coarse gold reported to the flotation tail.