Mt Thirsty Cobalt-Nickel Project
The Mt Thirsty Project located 16km north-northwest of Norseman, Western Australia. The Project is a 50/50 Joint Venture between Barra and Conico Ltd.
Cobalt-Nickel Oxide Deposit
The Project hosts the Mt Thirsty Cobalt Oxide Deposit (Table 1) which has the potential to emerge as significant producer of cobalt.
Extensive metallurgical test work in recent years has indicated that high recoveries of cobalt can be achieved via an efficient low temperature, atmospheric leaching process which uses sulphur dioxide (SO2) as the preferred reagent, resulting in a more practical and economic leaching method by specifically targeting cobalt attached to manganese oxides within the deposit.
Table 1: Mt Thirsty Cobalt Oxide Deposit Mineral Resource Summary (Un-cut)
This Mineral Resource was first disclosed under the JORC code 2004. It has not been updated since to comply with JORC 2012 on the basis that the information has not materially changed since it was last reported. Refer to ASX announcement 8/3/2011.
On 5 October 2017, the Mt Thirsty Joint Venture (MTJV) released the Scoping Study results, demonstrating a robust set of financial metrics over a 21-year mine life.
The Scoping Study returned a preferred case Net Present Value (NPV) of A$290 million (within a range of A$245 million to A$335 million) over a 21-year mine life with a low capital cost of A$212 million (incl. A$34 million contingency), with a healthy 21.5% Internal Rate of Return (IRR) and an expected 4-year pay back. Life of mine operating costs are projected to be A$43 per tonne of treated ore due to the very low reagent consumption.
The plant will employ an atmospheric sulphur dioxide leaching process with overall base case metal recoveries of 73% for cobalt and 21.5% for nickel. Planned optimisation testwork will focus on significantly improving metal recoveries.
The first 5 years of production will be targeting up 1,900 tonnes of cobalt and up to 1,760 tonnes of nickel. Over the life of the mine, up to 27,000 tonnes of cobalt and up 35,000 tonnes of nickel will be potentially produced.
Cobalt Price Sensitivity
The Mt Thirsty Cobalt Project is highly leveraged to cobalt prices with approximately 80% of revenue being from cobalt; far higher than other nickel laterite projects. Figure 1 illustrates the effect alternative long-term cobalt prices have on the Net Present Value (NPV) of the Scoping Study. All other variables from the Scoping Study are fixed in this analysis.
The Pre-Feasibility Study to commence in 2018 will test significant further upside value in all areas and de-risk the project.
Nickel Sulphide Mineralisation
In addition to the Cobalt-Nickel Oxide Resource, the Mt Thirsty Project has proven potential to host primary nickel sulphide mineralisation within the same ultramafic sequence that hosts the oxide resource.
The thick sequence of altered olivine-rich, cumulate-textured ultramafic rocks contain semi-massive, stringer and disseminated nickel sulphide mineralisation. The footwall contact where the best concentration of nickel sulphides might be expected has been systematically tested with RC and diamond drilling. RC drilling to date has returned nickel sulphide intersections including 6m @ 3.4% nickel, 2m @ 5.9% nickel, 2m @ 3.5% nickel and 1m @ 4.0% nickel.
Longitudinal section showing nickel sulphide intersections.