Junior nickel-copper-PGE explorer St George Mining has confirmed the potential to produce two commercially viable concentrates with metallurgical test work at the company’s Stricklands deposit displaying nickel grades of 11.5 per cent with 3.32 grams per tonne palladium, 0.65 g/t platinum and 0.61 per cent cobalt. Additionally, copper showed a 27.8 per cent yield with 12.4 g/t palladium, 1.9 g/t platinum and 2.6 g/t gold.
Importantly no deleterious elements that could affect the saleability of the concentrates were identified.
Metallurgical test work was undertaken at the Stricklands deposit within the company’s flagship high-grade Mt Alexander project, located in the north-eastern goldfields. Test work utilised composites of massive and disseminated ore from Stricklands with the aim of replicating a potential life-of-mine ore scenario.
Samples used for test work contained approximately 90 per cent fresh sulphides with the key mineralogical difference showing a primarily pentlandite and pyrrhotite hosted fresh rock sample versus a violarite and pyrite dominated specimen in oxidised ore. The theoretical metallurgical recovery rates are deemed to be very similar between oxidised and fresh sulphide bearing rock.
The major factor affecting recovery potential is the proportion of disseminated ore due to silicates in disseminated ore being non-recoverable nickel carriers.
Ore samples were tested using conventional flotation methods and standard re-agents and have been confirmed as amenable to the industry-standard processes.
The detailed test work was undertaken by a subsidiary of Glencore, XPS, who have internationally recognised credentials as leaders in metallurgical processing solutions within the nickel-copper sulphide space.
Whilst the work has been busily happening behind the scenes, St George has been examining a new opportunity to add further shallow nickel-copper sulphide mineralisation to the potential resource inventory with minimal additional cost.
A massive sulphide lens located approximately 350m to the west of the main Stricklands project area has been prioritised for a drill out to boost resource estimate numbers.
Assays are still pending from a program undertaken in 2021 targeting massive sulphides at the company’s Cathedrals project nearby with fresh massive nickel-copper sulphides starting 20m below surface.
With metallurgical test work showing some very positive outcomes for the Stricklands deposit – St George has the confidence to go full steam ahead towards a drill out to get a resource estimate wrapped around Stricklands. With nickel experiencing unprecedented highs off the back of supply concerns, St George may have chosen the right commodity at the right time.
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By Matt Birney
