Basically when a gravity process is able to recover more than 50% of gold, the potential presence of free or native gold is important. If the gold recovery is low, it is necessary to consider more alternatives such as flotation and cyanidation. There is a usual or common classification about gold ores based on its recovery by cyanidation. If the recovery is more than 90%, the ore is considered as free-milling ore. In the same way, a refractory ore is considered if the material gives low recovery by cyanidation and some extra process will be required to enhance the process performance.
In order to improve the performance is important to carry out mineralogical studies of gold behavior in various ores and metallurgical products in order to classify the ore and address issues and problems related to gold ore processing. It is widely used as a predictive and trouble-shooting tool in gold ore processing, and provides useful information on process selection, flowsheet development, recovery improvement, and reagent consumption optimization.
The main gold ore types are listed below,
- Placers
- Leachable
- Weathered
- Silver-gold
- Iron sulphide minerals
- Base metal sulphides
- Gold tellurides
- Non-sulphide gangue
- Carbonaceous ores
- Arsenic minerals
- Antimony minerals
- Tarnished Gold Particles