The Lumwana West project is located in the Central African Copperbelt, North-Western Province, Zambia. The area is prospective for large tonnage, low to medium grade copper/cobalt deposits. There are several major mines nearby to Lumwana West that are hosted in similar geological settings.
Argonaut, via its 90% held subsidiary, Mwombezhi Resources Ltd, has been successful in intercepting broad copper and cobalt intercepts at the Nyungu deposit and has defined a series of large, prospective targets that have now undergone first-pass drill testing.
Nyungu Copper-Cobalt Deposit
The Nyungu Copper-Cobalt deposit was drilled by Argonaut in 2011 and 2012. 48 drill holes for 9,019m targeted copper mineralisation, rather than cobalt, due to the metal prices at the time.
Initial drilling targeted fresh copper sulphide mineralisation i.e. copper mineralisation below the weathered (oxide and transitional) zones. Cobalt mineralisation tends to sit at the footwall of the Nyungu Central deposit in a relatively predictable manner, typically with grades of 0.1%. Wide high-grade zones, such as 23m at 0.21% cobalt, have been intercepted. Three cobalt domains have been defined using wireframes for estimation purposes. These cobalt domains sit within the envelope of copper mineralisation.
The Nyungu Central deposit plunges gently to the north. Existing drill holes targeted this plunging mineralisation to approximately 300m below the surface. The cobalt grades increase down-plunge and copper grades stay roughly consistent.
The preliminary mining study clearly demonstrates that deeper drilling is now warranted at Nyungu Central due to the low stripping ratio, favourable deposit geometry and increased cobalt value. This drilling will increase the contained tonnages of both copper and cobalt.
Argonaut has engaged RPM to carry out a Resource estimation to JORC standards for the Nyungu copper-cobalt deposit. Argonaut will report on the outcome of this work once a final report has been completed. A Resource estimation would replace the Exploration Target estimation summarised below.
Argonaut has commenced a scoping economic study into three potential processing flowsheets. These flowsheets involve:
- Crush > grind > flotation > sale of concentrate
- Crush > grind > flotation > roasting > leaching > SX/EW > sale of copper metal
- Crush > grind > flotation > albion process > precipitation > SX/EW > sale of copper metal
Data to achieve a meaningful economic projection is being generated at present and economic results will become available progressively.
Revised Exploration Target
The estimation of an Exploration Target including cobalt as well as copper was announced by Argonaut in March 2017. The revised Exploration Target is:
||Tonnage Range (Mt)
||Grade Range (%)
||Contained Metal Range (kt)
||130 to 180
||0.45 to 0.65
||580 to 1,150
||15 to 20
||0.08 to 0.12
||12 to 24
The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource.
* Copper Exploration Target announced to the ASX by Argonaut on 9 April 2013.
^ Cobalt Exploration Target announced to the ASX by Argonaut on 28 March 2017.
The March 2017 Exploration Target is estimated to JORC 2012 standards.
Resource and exploration drilling commenced in July 2021 at the Nyungu Central and Nyungu South deposits (Figure 1). Resource drilling at Nyungu Central will infill spacing from 200m to 100m to provide density of drilling to JORC resource standards (Figure 2).
Figure 1. The Nyungu Central and Nyungu South deposits are defined by broad copper intercepts
Figure 2. Nyungu Central cross sections showing existing and planned drill holes