Using a cobalt price of about US$84,000 per tonne, Kalongwe has a pre-tax net present value of $186 million and an internal rate of return of 99%.

Last year the company used $40,000/t, with a copper price of $3 per pound modelled in both instances.

Nzuri described its cobalt pricing assumptions as "still conservative".

Cobalt is currently trading at about $92,000/t having reached levels around $95,000/t last month - after having been little more than $20,000/t early in 2016.

Nzuri is currently undertaking a front-end engineering design program due to be completed next quarter, with funding options also being evaluated and a feasibility study on a SXEW development set for the September period.

The company expects to be in production in 12 months after project funding is secured.

Kalongwe's initial annual production profile is put at 18,657t of copper and 1370t of cobalt, with capex still $53 million and cash costs falling from $1.35/lb of copper (net of cobalt credits), to 85c/lb.

Shares in Nzuri were up 4% to A36.5c in morning trade, capitalising the company at $98 million.

Nzuri had $6 million cash at the start of April.