Collerina Cobalt , following on from the recent successful drill program which intercepted high grade nickel, cobalt and aluminium within wide mineralised intercepts, has now commenced its metallurgical test work program aimed at initially producing a mixed cobalt‐nickel sulphide precipitate which will be further economically enhanced through the production of HPA.
Approximately 45 kg of composite material representative of the main Homeville deposit have been received by Core Metallurgy’s lab in Brisbane. These samples will be crushed to 100% passing 25 mm then blended and split into representative sub‐samples with a sufficient amount milled until the sample is 90% passing 0.25 mm (nominal) for head characterisation and leaching tests.
The ground samples will then be blended and split into representative sub‐samples using a rotary splitter, a representative head sample will be riffle split for elemental characterisation including Al, Co, Cr, Fe, Mg, Ni, Sc and Si.
A series of four eight-hour atmospheric acid leaches in a 5 litre reactor at nominally 30% w/w solids density of the blended sample will be undertaken, during the course of the leach tests kinetic samples will be taken (nominally) at 2, 4 and 6 hours for analysis of both solid and liquid phases for determination of Al, Co, Cr, Fe, Mg, Ni, Sc and Si recoveries.
In the first stage, fresh ore is leached in a lower free acid solution, leaching the readily leachable material and producing a pregnant leach solution with relatively low residual acidity. The leach residue solids from the first stage are washed and forwarded to the second stage of leaching. In the second stage of leaching, concentrated sulphuric acid is used and the more tenacious material is leached by the higher concentration of acid. The leach solution from the second stage, with a much higher residual acid concentration, is recycled to the first stage leach as the acid source.
The CCAL will produce a low acidity leach solution. After appropriate pre‐treatment, the pregnant solution will be subjected to testing using a proprietary solvent extraction and refining process with an aim to produce 4N HPA (99.99% purity). The liquor remaining after aluminium extraction contains the cobalt and nickel values that would be recovered in the commercial plant to produce separate high purity nickel and cobalt products (metal, sulphate, carbonate, hydroxide or other forms).
The Collerina project lies about 40 km south of Nyngan in the central and western region of NSW, Australia, within the Lachlan Fold Belt which hosts a number of worldclass copper‐gold mines including the Cadia, Ridgeway and Northparkes operations. The district also hosts the globally significant Syerston Co‐Ni deposit owned by Clean Teq Holdings which contains a reported 109 Mt of 0.10% Co and 0.65% Ni. The deposit is currently under definitive feasibility study.
The mineralisation identified by the current drilling program is spatially associated with the previously announced JORC compliant nickel laterite resource of 16.3 Mt of 0.93% Ni and 0.05% Co at a 0.7% Ni cut‐off grade (4.4 Mt Indicated resource of 0.99% Ni and 0.06% Co and 11.9 Mt Inferred Resource of 0.91% Ni and 0.05% Co).
