St George Mining (ASX: SGQ) reports that it has confirmed potential for commercially-attractive nickel and copper concentrates following a metallurgical program at its flagship Mt Alexander Project in Western Australia’s north-eastern Goldfields.
The testwork produced ‘high-grade’ nickel and copper concentrates with strong credits for PGEs, cobalt, and gold from the Stricklands Deposit. This included nickel concentrate grading 11.5% Ni with 3.32 g/t Pd, 0.65 g/t Pt, and 0.61% Co, and copper concentrate grading 27.8% Cu with 12.4 g/t Pd, 1.9 g/t Pt, and 2.6 g/t Au.
Importantly, the concentrates produced did not contain any deleterious elements that could affect saleability.
The detailed metallurgical programme was completed by XPS, a Glencore Company, with internationally recognised credentials as leaders in metallurgical processing solutions for nickel-copper sulphide mineralisation.
Addressing the results, St George Mining Executive Chairman John Prineas said: “Our mineralisation at Mt Alexander has a unique combination of high-grade nickel, copper, cobalt and platinum group metals which we believe has potential to produce concentrates of exceptional value.
We are very pleased that the detailed metallurgical programme by XPS has confirmed that widely-used flotation techniques can produce separate clean concentrates for nickel and copper, with both concentrates also showing high payable credits for other metals including palladium, platinum, gold and cobalt.
“These results, supported by a flowsheet for potential commercial production, are an important milestone for the starter mine concept at Mt Alexander”
These results, supported by a flowsheet for potential commercial production, are an important milestone for the starter mine concept at Mt Alexander. Further optimisation work will be considered as we progress marketing studies with potential off-take customers.
With the prices for all metals in our commodity suite at historical highs, we will also look to expand the area of known mineralisation to include additional high-grade massive sulphide lenses intersected in previously announced drilling as well as untested targets at shallow depth surrounding the Stricklands Deposit.”
Testwork was undertaken on mixed massive and disseminated sulphide ore from the Stricklands Deposit at the Mt Alexander Project, replicating a potential life-of-mine ore. The ore samples were confirmed as amenable to processing with conventional flotation methods using standard re-agents.
A sequential flotation flowsheet was employed consisting of a copper float, followed by a nickel float. A rougher stage was followed by three cleaner stages and locked cycle testing.
Within locked-cycle flotation testing, the copper recovery was a combined 95.9% to the copper and nickel concentrates, of which 80.9% of the copper occurred in a 27.8% Cu concentrate. Nickel concentrate grade was 11.5% Ni with a nickel recovery of 68.7% to the nickel concentrate, equivalent to 95% of the nickel sulphide mineral content of the ore. Precious metals recoveries to the combined concentrates were 74% for Au, 59% for Pd, and 47% for Pt with both concentrates carrying the precious metal content.
Overall, the nickel and copper concentrates produced are considered of high quality which would be commercially attractive to potential offtake partners.
The Mt Alexander Project is located 120km south-south-west of the Agnew-Wiluna Belt, which hosts numerous world-class nickel deposits. The Project comprises six granted contiguous exploration licences, along with a seventh granted exploration licence located to the south-east of the core tenement package.
The Cathedrals, Stricklands, Investigators, and Radar nickel-copper-cobalt-PGE discoveries are held in a joint venture by St George (75%) and Western Areas Limited (25%). St George is the manager of the project, with Western Areas retaining a 25% non-contributing interest (tenement E29/638 only) until there is a decision to mine. All other project tenements are owned 100% by St George.
The company reports that additional optimisation work would be expected to further enhance concentrate grades and metal recoveries in a production scenario.
Images: St George Mining Limited
