The plant uses the company's patented minerals processing technology to treat pyrite feedstocks for recovery of 85-90% of cobalt in the form of mixed hydroxide precipitate or cobalt sulphate.

In the tests, the 500t parcel was milled, from 4mm top size to 1.5mm top size with a roller mill, to simulate the use of a high-pressure grinding roll mill in the circuit.

Feed rates to the kiln were 150-200kg per hour.

That produced 125t of concentrate with grades ranging from 500-1000 parts per million, which was then sent through the gravity circuit for upgrading.

Cobalt in ore was upgraded to about 4300 in concentrate, with mass rejection of 75% to tailings.

Cobalt Blue CEO Joe Kaderavek said a further 2500-3000t of ore are expected to be concentrated over the next four weeks.

"The approximate five-times grade improvement from concentration is a key project enabler," he said.

"Phase one of this large-scale work is continuing to confirm expectations."

Kaderavek said as part of the second phase of test work, a ball mill would be used to supply the circuit with a finer feed material, with a float circuit to also recover fine fractions of pyrite.

"Further work is ongoing to improve off-gas handling for recovery of the sulphur," he said.

"The next unit block for operations are the leach and mixed hydroxide precipitate production circuits during October."