Huge Yukon copper-gold mine heads to environmental review

Owned by Casino Mining Corporation, a subsidiary of Western Copper and Gold (TSX:WRN), the Casino mine is expected to produce over 400,000 ounces of gold per year and more than 200 million pounds of copper. Molybdenum and gold-silver doré bars would also be produced. Concentrates would be trucked to the port of Skagway, Alaska for ocean shipment. Up to 1,000 jobs would be filled at peak construction and the mine would employ about 600 people during its 22-year life, according to the company’s project page.

A 2013 feasibility study has the mine producing an average of 399,000 ounces of gold, 245 million pounds of copper, 15 million pounds of molybdenum, and 1.8 million ounces of silver per year during the first four years of production. At the time of the study, the copper price used to calculate the $1.8 billion net present value (after tax) was $3 a pound, and the gold price $1,400 an ounce. Both have dropped substantially, but according to Western Copper and Gold, the feasibility study “shows favourable economics, even at today’s low commodity prices.”

“Having the Casino Project moved to a Panel Review at this stage removes the uncertainty that the Project will be referred later in the assessment process, potentially saving the Company time and money. The decision will provide Western with an opportunity to engage the broader public in addition to Federal, Territorial and First Nation governments, and to demonstrate that the Casino mine can be built without significant adverse effects,” WRN said in a statement. The company’s stock rose 3.03 percent Friday following Thursday’s announcement.

Other interesting facts about the mine include:

• An on-site liquefied natural gas (LNG) power plant will be used to generate the needed 150 megawatts of power for mine operations. The LNG will be trucked to site from northeastern British Columbia.
• Freshwater will be supplied from the Yukon River, via a 17-km long pipeline with four booster stations at a rate of 3,400 m³/hr.
• The Tailings Management Facility will be located southeast of the Open Pit, in the valley formed by the headwaters of Casino Creek. The facility will be a 1,120 hectare area formed by the construction of two earth/rockfill/cyclone sand, zoned embankments. The facility will store 947 million tonnes of tailings produced by the processing plant, and 658 million tonnes of potentially reactive waste rock generated through mining. The main embankment will be 286 m high at the deepest section of the Casino Creek valley, and will be sequentially raised throughout operation by cyclone sand made from the tailings, to reduce the volume of tailings requiring storage. The facility will retain the tailings and waste rock in a sub-aqueous state to ensure geochemical stability of the waste material. According to CBC, the earth-fill dam would be one of the world’s highest dams, and the highest tailings dam.
• The Heap Leach Facility is on a southeast facing hill-slope south of the Open Pit and will stack and leach 157.5 million tonnes at a nominal rate of 9.125 million tonnes per year. The facility has been designed with special design and operational consideration to account for the cold climate, and the presence of extensive permafrost. It will be developed in five stages by loading in successive 8-m lifts upslope from a confining embankment to provide initial stability and minimize initial capital costs.