Cobalt-pyrite concentrates were produced from 45 tonnes of ore samples that originated from the previous two drilling programs.
The results were in line with key outcomes obtained in the pre-feasibility study and add confidence that the target mass recovery to concentrate is about 20% and a target cobalt recovery from ore to concentrate of more than 90%.
Key metallurgical work program summary
The weighted average recovery of cobalt from the entire 44.5 tonnes of ore to cleaner gravity concentrate was 68%, from a weighted average head ore grade of 1,002 ppm.
Concentrate cobalt grade averaged 4,655 ppm and the mass recovery was 14.5%.
The results will be used by Cobalt Blue to optimise its process engineering design criteria and the produced concentrate will be used for thermal decomposition trials.
A follow-up program is expected later this year, with 40-50 tonnes of reverse circulation and diamond drill core samples stored in Broken Hill.
Summary of concentrate circuit mass and cobalt recoveries (flotation recoveries to be confirmed)
Ore was screened at 1,180 microns, with oversize crushed to meet the upper particle size threshold.
Samples were then passed over commercial-sized gravity spirals working in a rougher-cleaner sequence, with the tails then forwarded to flotation cells.
To date, 45 tonnes of ore have been gravity separated and final work is ongoing for recovery of sulphides from the gravity circuit tails.
The gravity rougher concentrate was reprocessed through a gravity cleaner circuit and the rougher tails were classified prior to scavenger flotation, whereas the cleaner tails were forwarded directly to flotation.
Results from the flotation circuit are expected to be finalised next month.