NWT’s CanTung mine now in full swing

Only six months after the start of plant rehabilitation, North American Tungsten (NTC-V) has entered production at its wholly owned CanTung mine in the Northwest Territories, about 310 km northeast of Watson Lake in the Yukon.

The first ore was crushed in late January and milling has progressed at the daily throughput rate of 500 tonnes. This will gradually be increased to 700 tonnes by the end of February and thence to the full rate of 850 tonnes. The first shipment of concentrate left the mine in early February. North American Tungsten forecasts its annualized high-grade tungsten concentrate to exceed 3,000 tonnes.

“We have brought our CanTung mine into production over a short time frame, and although some investors and market-followers expected instant results and gratification, startup of production is a process rather than an event,” says company president Udo von Doehren. “In spite of harsh winter conditions, the process is going well and our operating team is to be commended for their enthusiasm and dedication in preparing the operation for full production.”

Last year, the company entered into agreements with two leading producers of tungsten products: Pennsylvania-based Osram Sylvania Products (a subsidiary of Siemens of Germany) and Stockholm-based Sandvik. The two companies pitched in a cash advance totalling US$3 million (to be repaid in 36 months) and agreed to buy, over three years, all of concentrate production from CanTung. This output is estimated to be 9,000 tonnes.

The agreements provide a guaranteed floor price and a scaled discount from quoted tungsten commodity prices, and Sandvik and Osram are entitled to participate in the development of any of North American Tungsten’s other tungsten interests, such as the MacTung mine, 160 km to the north.

CanTung’s reserves are pegged at 630,000 tonnes grading 1.82% tungsten trioxide. MacTung contains a measured, indicated and inferred resource of roughly 30 million tonnes grading 0.93% tungsten trioxide.

The CanTung deposit was discovered in 1958 by prospectors who identified scheelite mineralization hosted in a sulphide-bearing skarn. Over the following three years, crews delineated an open-pit deposit with reserves of 1.3 million tonnes grading 2.5% tungsten trioxide and 0.5% copper. The mine was commissioned in 1962 and operated until 1986, when low tungsten prices resulted in a shutdown. The mine produced high-grade scheelite concentrates in excess of 75% tungsten trioxide, as well as lower-grade concentrates averaging 35% tungsten trioxide. The product was shipped to markets in the U.S. and western Europe. In 1997, North American Tungsten purchased the CanTung mine and the MacTung property from Aur Resources (AUR-T).

The region is underlain by a series of late Proterozoic-to-Mississipian-aged sedimentary rocks of the Selwyn basin. The rocks range from argillite, with minor carbonates, to dolomite and quartzite. The mine area is characterized by a northwest-trending synclinal structure that is intruded by Cretaceous-aged quartz monzonite to granodiorite plugs.

The CanTung scheelite deposits were formed by metasomatism within the thermal aureole of a granodiorite-quartz monzonite intrusion. The main tungsten mineralization is hosted in a limestone unit that is folded into a recumbent anticline. The open pit was on the upper limb of the fold, whereas the underground E-zone is on the lower limb of the fold, about 300 metres. below the pit. Scheelite is the only tungsten mineral identified at CanTung; it is associated with pyrrhotite and minor chalcopyrite. Most of the remaining resources are underground, in the West Extension zone.