Cobalt Blue Holdings Ltd (ASX:COB, OTC:CBBHF) will proceed to the next stage of testing its proprietary minerals processing technology on Hudbay Minerals Inc’s Flin Flon tailings storage facility in Manitoba, Canada, after positive results from preliminary roasting test-work.
The completed roasting tests achieved greater than 90% conversion of the pyrite into pyrrhotite and elemental sulphur with these results warranting further evaluation.
In late June, COB entered into a test-work co-operation agreement with respect to Hudbay’s wholly-owned Flin Flon tailings storage facility.
READ: Cobalt Blue in tailings testing agreement with Canadian producer Hudbay Minerals
Hudbay estimates that the tailings facility contains in excess of 100 million tonnes from around 90 years of operations, which ceased in 2022.
Reprocessing opportunity
In 2021, Hudbay identified the opportunity to reprocess Flin Flon tailings and subsequently completed a confirmatory drilling program covering about two-thirds of the tailings facility.
Assay results from Hudbay’s drilling program indicated higher zinc, copper and silver grades than predicted from historical mill records while confirming the historical gold grade.
As part of the co-operation agreement, COB's processing technology is being used to assess the ability to recover gold, silver, copper, zinc, cobalt and sulphur from a pyrite/pyrrhotite concentrate produced from the tailings.
Positive roasting tests
A 50-kilogram sample of tailings from Flin Flon has been received with preliminary roasting test work completed. The sample contained:
- Approximately 0.8% zinc, 0.1% lead, 0.2% copper and 200 ppm cobalt; and
- Approximately 40% pyrite.
Laboratory scale ‘proof-of-concept’ test-work was completed including flotation, thermal decomposition of pyrite and leaching of kiln calcine.
The overall results successfully achieved >90% conversion of the pyrite into pyrrhotite and elemental sulphur.
These results will be used to design an overall flowsheet for the treatment of the tailings as part of the final test work.
COB’s processing technology
COB has been developing minerals processing technology for the extraction and recovery of cobalt and elemental sulphur from cobalt-pyrite feedstocks.
The technology is focused on the treatment of pyrite, to recover payable metals, elemental sulphur and generate environmentally stable iron oxide leach residues.
This process specifically avoids the simultaneous production of sulphuric acid, which normally occurs when roasting pyrite or leaching pyrite via pressure oxidation.
The technology has progressed to a Demonstration Plant scale in Broken Hill, Far West New South Wales.
During the execution of feasibility studies supporting COB's Broken Hill Cobalt Project (BHCP) this Demonstration Plant has completed more than 2,000/600 hours of kiln/autoclave operations at near commercial scale with resultant production of hundreds of kilograms of commercial cobalt chemicals.
Previously, COB had successfully evaluated the application of the technology to cobalt-pyrite feedstocks from other locations within Australia, namely North Queensland and South Australia.
One of company’s strategies
“Reprocessing mining waste containing pyrite and recovering metals remains a focus for our business, said COB’s chief executive officer Joe Kaderavek.
“Generally, the opportunities include cobalt-containing pyrite, along with other base and precious metal sulphides such as copper, zinc and gold.”
The technology is part of COB’s Cobalt in Waste Streams Project, one of three key strategies being pursued in the company’s integrated cobalt supply strategy to serve the growing global demand for clean, green energy systems.
What comes next?
If the final test work results meet expectations, then further discussions concerning the next stages of technical cooperation will be held.
Future collaboration may include larger-scale test work in parallel with potential commercial negotiations.