While all of the processes we use exist in mining around the world - we have brought them together in an innovation that is unlocking cobalt from pyrite in these steps:
Concentrate
Ore is crushed to approx. 1 mm, and a pyrite concentrate is recovered using a combination of gravity and flotation unit operations.
Calcine
The pyrite concentrate is thermally treated under an inert atmosphere to produce artificial pyrrhotite (calcine) and elemental sulphur. The sulphur is condensed from the kiln off-gas and turned into solid prills.
Leach
The pyrrhotite is forwarded to a low-temperature, low-pressure autoclave for leaching. The leach residue is removed by filtration and further processed for sulphur recovery by remelting. The leach solutions are advanced through various minor metals removal steps (precipitation, ion exchange, and solvent extraction) to remove iron, copper, zinc, manganese. The cobalt and nickel are precipitated as a mixed-hydroxide (MHP) intermediate.
Product Recovery
The MHP is then refined for production of high purity cobalt sulphate heptahydrate.