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ASX-listed Argonaut Resources has announced preliminary details of potential copper and cobalt production at the Nyungu copper-cobalt deposit in North-western Zambia.
The Nyungu copper-cobalt deposit is part of the Lumwana West project, located 65 km south of the DRC border in North-western Zambia.
Cobalt deposit
Existing drilling by Argonaut has defined between 12,000 and 24,000 t of contained cobalt at the Nyungu deposit in Zambia
Planned follow-up drilling at Nyungu is likely to increase cobalt and copper tonnage
Exploration upside
Peak cobalt in diamond drilling is: 81.5 m at 0.12% cobalt from 183 m, including 23 m at 0.21% cobalt from 218.5 m in drill hole NYRD046
Further drilling of shallow oxide and transitional zones and the northern, down-plunge extension of Nyungu Central in Zambia is likely to yield greater tonnages at encouraging grades
Argonaut has collected soil samples over the entire Lumwana West licence area in Zambia and each of these samples was analysed for a suite of elements, including cobalt. Several high-order cobalt soil anomalies have been identified for follow-up exploration
Peak cobalt in soil is 0.15%
Metallurgical test work
Potential exists for a two-stage, low capital cost, short lead-time copper-cobalt mine.
Stage one – dense media separation of cobalt oxide.
Stage two – heap leach and solvent extraction of copper and cobalt sulphides.
Metallurgical samples have been selected from existing drill core and these samples are being exported to Australia for testwork
Initial testwork will involve a mineralogical study of four mineralisation types
Follow-up metallurgical work may include:
- dense media separation of copper and cobalt oxide
- leaching of copper and copper-cobalt sulphide; and
- conventional flotation of copper-cobalt sulphide
Mining study
Preliminary open pit optimisation by RPM shows excellent deposit geometry via a very low stripping ratio.
Stripping ratio of 1.5 to 1 for the optimum pit at the current copper price; and stripping ratio of 2.3 to 1 to a depth of >300 m at 150% of the current copper price, indicating the deposit has a low sensitivity to stripping ratio.
RPM concluded the project had economic potential and warrants further studies.
Tenure
The Lumwana West large-scale exploration licence was recently reissued for a maximum period of 11 years.
Cobalt deposit
The Nyungu Copper-Cobalt Deposit was drilled by Argonaut in 2011 and 2012. 48 drill holes for 9,019 m were considered by RPM in its recent studies of Nyungu.
This drilling targeted copper mineralisation, rather than cobalt, due to the metal prices at the time.
Cobalt mineralisation tends to sit at the footwall of the Nyungu Central Deposit in a relatively predicable manner.
Cobalt grades are typically 0.1%. Wide, high grade-zones, such as 23 m at 0.21% cobalt, have been intercepted.
Three cobalt domains have been defined using wire-frames for estimation purposes. These cobalt domains sit within the envelope of copper mineralisation.
Copper and cobalt exploration targets
RPM have previously estimated exploration targets for both copper and cobalt mineralisation at Nyungu. Both Exploration Targets are estimated to JORC 2012 standards. Argonaut is planning to undertake a drilling program of at least 3,000 m as soon as possible.
