Reagent | Toxicity | Advantages | Disadvantages |
Cyanide | Very high | High dissolution rate | Environmental issues |
Agua Regia | High | High dissolution rate | No feasible large scale applications |
Chlorination | Medium | Proven technology | No feasible large scale applications |
Good efficiency | High temperatures required | ||
Bromine & Iodine | Low | High dissolution rate | High reagent costs |
Thiocyanate | Medium | Recyclable | No feasible large scale applications |
Limited availability | |||
Thiosulfate | Medium | Cheap reagent | Detoxification costs |
High reagent consumption | |||
Thiourea | Medium | Proven technology | Dissolution of heavy metals besides gold |
High dissolution rate and speed | |||
Bacteria | Low | Reduction of reagent consumption | Slow reaction |
Higher leaching yield | Difficult process control |