BRITISH COLUMBIA – Chieftain Metals of Toronto says the completed feasibility study is “robust” for its Tulsequah Chief zinc-gold-copper deposit 100 km south of Atlin. The study yielded a pre-tax net present value (8%) of $192.7 million and an internal rate of return of 16.5%. The post-tax NPV (8%) will be $146.0 million and IRR 14.9%.
Chieftain said the study considered a 2,000-t/d underground mine with a nine year life. Pre-production capital costs will total $439.5 million, with an additional $64.0 million in sustaining capital. Closure costs, net of salvage value, will be $6.2 million.
The Tulsequah probable reserve totals 6.45 million tonnes grading 5.59% Zn, 2.30 g/t Au, 1.12% Cu, 1.04% Pb and 81.38 g/t Ag. During the mine life, the study expects that 403,900 oz of gold, 11.97 million oz of silver, 601.5 million lb of Zn, 135.5 million lb of Cu, and 93.0 million lb of lead will be recovered.
The underground mine will be adjacent to and below the old workings that were operated by Cominco from 1951 to 1957. The new mining areas will be accessed through the existing 5200 and 5400 level adits. A spiral ramp that will accommodate haul trucks will be developed to a vertical depth of 750 metres with mining levels cut at 30-metre vertical intervals. The primary mining method will be sub-level stoping, although a small amount of mechanized cut-and-fill stoping will take place. Backfill will consist of paste (cemented as necessary) and unconsolidated loose waste rock.
The 2,000-t/d mill will be based on a conventional flotation flowsheet. It will operate two shifts per day, 365 days per year with an expected availability of 92%. Copper, lead and zinc concentrates as well as gold-silver doré will be produced. The tailings facility will be built 5 km north of the mine in the valley of Shazah Creek.
More details from the Tulsequah Chief feasibility study are available at ChieftainMetals.com in the news release dated Dec. 11, 2012.