There have been some advances in operating aspects of flotation. Also, selectivity, recoveries and concentrate grades have changed according to the complexity of the gold ore and the operation. It is important to indicate that the cost of obtaining these selectivity and recoveries can be reduced. Thus, it is notable that nearly all the collectors and employed today were or are obtained from reagents developed forty years ago. This is due to their efficiency and relatively cheapness. Some manufacturers are used to promote especial reagents (especially collectors), but the performance is influenced by several aspects and probably for this reason gold flotation plants have a xanthate such as potassium amyl xanthate as the main collector and its collection is difficult to replace. Weak collectors only reinforce the collecting action of xanthates. It has been detected that existing reagents that are out of the basic and ideal requirements. Unsatisfied needs include optimal recovery non-sulphide copper minerals containing precious metals, improved selectivity in some separations, improved recoveries for mixed oxide-sulphide ores and free gold and reduced lime consumptions that usually accounts for half of total reagent costs and complicates downstream processing. A good example is the gold-copper operation of Cerro Corona in the north of Peru. The ore body contains oxide copper minerals with important contents of gold and its recovery by flotation is extremely low.
Maybe, the acceptation that flotation is an electrochemical process has drawn many researches in that direction. Essentially, the main objective is to create a oxidation-reduction condition in the slurry where the collector will only adsorb on the gold-bearing mineral surface. Since each mineral has different respond at different potential, it can be depressed or floated just modifying the potential. A series of gold-bearing minerals can be selectively floated from each other. The main advantage of potential control is related to the consumption of reagents. Also it has been noted that an excess of calico ions in solution tend to reduce the flotation of gold-bearing minerals. For this reason, many manufacturers of flotation reagents have been focused on developing new reagents based on the potential mechanism as part of ongoing research into mining chemicals applied to recovery of gold by flotation.
Cyanidation has been used extensively for a long time and the chemistry of the process is basically the same. The main problem with the consumption of cyanide is related to the presence of cyanicides or minerals that are dissolved the first moments. Oxide copper minerals are the typical case and the mine must identify and coordinate the presence of the undesirable minerals in the process. In other circumstances the consumption of cyanide must not be a problem, and especially in heap leaching operations whose application is based on low operating costs. Other consideration oriented to reduce costs is related to recycle the barren solution in order to use the free cyanide and remaining alkalinity. Try to get the equilibrium is important.