The Mining Method
The mineralized rock at Donlin Gold would require multiple steps in processing to extract the gold.
- Mineralized rock is first crushed, then ground in large mills to create a fine, silt-like powder.
- The gold-bearing minerals are then separated from other materials using a process called “flotation.”
- A process called “pressure oxidation” is used to oxidize the gold-bearing materials.
- The oxidized material is mixed with a cyanide solution in large tanks inside the mill. The gold dissolves in the cyanide.
- The dissolved gold is then collected onto activated carbon, and the cyanide solution is sent to a cyanide-detox unit. Any trace amounts of cyanide left in the tailings would break down further under natural conditions.
- The gold is then extracted from the carbon and refined into doré bars.