Clean Air Metals (TSXV: AIR) has released a preliminary economic assessment for its 100%-owned Thunder Bay North project putting the after-tax net present value with a 5% discount at C$389 million ($303m) and the internal rate of return at 29.8%.
Payback from the start of commercial operation would take 2.4 years with the initial capital expenditure estimated at C$367 million.
The copper-nickel-platinum group (PGM) project is located 50 km northeast of Thunder Bay, Ontario.
The PEA was prepared by Nordmin Engineering and examines underground mining at an average rate of 4,450 t/d (3,600 t/d ore and 850 t/d waste). It also includes a new stand-alone milling complex and tailings management facility. The mill would be fed from both the Current and Escape deposits.
The Current deposit is accessed via a portal from the surface and would have a 12-month development period. Mining in the Current and Bridge zones would occur in the first three years of production. In the fourth year, mining would begin on the High Grade zone of the Escape deposit.
When both mines are in operation, each will produce 1,800 t/d ore for the mill. Both longhole open stoping and drift and fill mining are planned.
A conventional semi-autogenous grinding (SAG)-pebble mill-ball mill circuit is proposed for the mineral processing plant. This would be followed by flotation to produce two marketable concentrates – copper-PGM and bulk. The two products could be sent to separate regional smelters.
Over a 10-year life, the Thunder Bay project could generate C$2.2 billion in total revenues. Total metal production during that time is expected to be 629,000 oz. platinum, 618,000 oz. palladium, 111 million lb. copper, 57 million lb. nickel, 38,000 oz. gold, and 850,000 oz. silver (2.9 million oz. platinum-equivalent).
The combined indicated resource for the Current and Escape deposits is 14.6 million tonnes grading 1.54 g/t palladium, 1.58 g/t platinum, 0.20 g/t gold, 2.30 g/t silver, 0.42% copper, 0.23% nickel, 167 g/t cobalt, and 0.05% rhenium.
The inferred resource is 8.1 million tonnes grading 0.69 g/t palladium, 0.67 g/t platinum, 0.07 g/t gold, 1.07 g/t silver, 0.33% copper, 0.15% nickel, 138 g/t cobalt, and 0.01% rhenium.
(This article first appeared in the Canadian Mining Journal)