Auroch Minerals Limited (ASX:AOU) has successfully been completed preliminary metallurgical testwork on the high-grade shallow nickel sulphide mineralisation directly south of the historic Nepean nickel mine at the Nepean Nickel Project in Western Australia.
Head assays were initially taken for the three composite drill-core samples with nickel grades up to 7.18% Ni for the massive sulphide sample.
Results from the metallurgical testwork indicated all samples responded well to conventional froth flotation, with rougher recoveries for nickel between 85% and 97%. Saleable concentrate grades in excess of 13% Ni were achieved for all three composite samples, albeit at a lower recovery (30%) for Sample 1, which is the subject of ongoing optimisation testwork.
All samples demonstrated minor non-sulphide nickel (NSNi) present. Sulphur speciation for the samples also indicated some degree of sulphide oxidation has occurred, consistent with the petrology which identified violarite as the dominant nickel sulphide species. No talc or deleterious elements were detected during the testwork.
Managing Director, Aidan Platel, said the results achieved during the preliminary metallurgical testwork programme are encouraging and further work would be expected to improve upon current results, especially with respect to Fe:MgO ratios of the final nickel concentrates produced.
He said the positive results from the testwork are an important milestone for the Nepean Scoping Study looking into the economic viability of a potential open-pit mining scenario of the known shallow high-grade nickel sulphide mineralisation, which commences within 50m from surface.
The company will now look to complete a JORC(2012)-compliant Mineral Resource Estimate (MRE) for the shallow high-grade nickel sulphide mineralisation at Nepean.
“We are very happy with the results from this first phase of metallurgical testwork at Nepean,” Mr Platel said.
“We knew we have very shallow, high-grade nickel sulphide mineralisation at Nepean that may potentially be extracted in an open-pit mining scenario, but because of the oxidation of the mineralisation being so close to surface, we were unsure if we would be able to produce a saleable grade nickel sulphide concentrate.
“The results are extremely encouraging and show that this shallow nickel sulphide mineralisation will indeed produce a saleable grade nickel concentrate, and furthermore that the nickel recoveries are more than acceptable.
“As such, the results justify continuing work on the Nepean Scoping Study, and the company will now commence work on updating the MRE for the shallow portion of the known nickel sulphide mineralisation at Nepean so that we can then begin work on mine designs and optimisation work on potential open-pit mining scenarios.”
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