Although primarily conceived as an alternative to the use of cyanidation for refractory and carbonaceous ores and concentrates, the Neomet Gold Process has a number of advantages.
| Operation | Pressure Oxidation (POX) | Bacterial Leaching | Roasting | Albion/ Activox | Nitric Acid | Neomet Chloride |
|---|---|---|---|---|---|---|
| Feed | Concentrate | Concentrate | Ore or Concentrate | Concentrate, ultra fine grind | Concentrate | Ore or Concentrate |
| Arsenic | Type II mineral, ferrihydrite finish, stable | Ferrihydrite, stable only if sufficient Fe in solution at time of precipitation | Arsenic trioxide, separate treatment plant required plus separate source of iron to make stable residue | Ferrihydrite, stable only if sufficient Fe in solution at time of precipitation | Scorodite, ferrihydrite finish, stable | Scorodite, no finish necessary |
| Residue disposal | Dedicated area, non-reducing | Dedicated area, non-reducing | Dedicated area, non-reducing | Dedicated area, non-reducing | Dedicated area, non-reducing | Dedicated area, non-reducing |
| Effluent issues | None if no K or Na dissolves | Bacteria cultures leaking into water table | Weak acid from scrubbers or acid plant | None if no K or Na dissolves | Nitrates leaking into environment | Chlorides into environment. However, wash efficiency so high, that such is minimal |
| Alkali metals | Potential to form KOH and NaOH on lime neutralization, which will slowly decompose As minerals. Potential to form jarosites, consuming acid and iron. | Potential to form KOH and NaOH on lime neutralization, which will slowly decompose As solids. Potential to form jarosites, consuming acid and iron. | No issues | Potential to form KOH and NaOH on lime neutralization, which will slowly decompose As solids. Potential to form jarosites, consuming acid. | Potential to form KOH and NaOH on lime neutralization, which will slowly decompose As minerals. Potential to form jarosites, consuming iron, but helping control sulphate balance. | K and Na separated, chloride recovered. Not mixed with As solids, therefore no impact. |
| Aluminium | Forms alunites, consumes acid, scaling issues | Will dissolve, consumes acid and lime | No issues | Will dissolve, consumes acid and lime | Will dissolve, consumes acid and lime | Dissolves, recovered with hematite. Can be recovered as alumina if sufficient present |
| Gold recovery | Cyanide in separate leach circuit, requires cyanide destruction. Long residence time (24-96 hours) | Cyanide in separate leach circuit, requires cyanide destruction. Long residence time (24-96 hours) | Cyanide in separate leach circuit, requires cyanide destruction. Long residence time (24-96 hours) | Cyanide in separate leach circuit, requires cyanide destruction. Long residence time (24-96 hours) | Cyanide in separate leach circuit, requires cyanide destruction. Long residence time (24-96 hours) | Direct from chloride leach as pure gold. Rapid turnaround time |
| Silver recovery | Along with gold as doré metal | Along with gold as doré metal | Along with gold as doré metal | Along with gold as doré metal | Along with gold as doré metal | Separately as pure silver or together with gold. |
| By-products | None | None | None | None | None | Can recover any PGMs, Ga, Sc, etc. |