Red Chris Mine
Commodities: Copper (Cu), Gold (Au), and Silver (Ag)
Location: 80 km south of Dease Lake and 18 km southeast of the village of Iskut.
Geology and Type of Deposit: Red Chris is located on the west edge of the Intermontane Belt of the Canadian Cordillera. The ore is a copper-gold porphyry type deposit that occurs in the Late Triassic age Red Stock, a monzonite that intrudes older sedimentary and volcanic rocks. Copper-gold mineralization occurs in a vertical zone within the main stock body. The main minerals are chalcopyrite and bornite. Gold occurs as a native element and within sulphide minerals.
The Operation: The area was first explored in the 1950s. Exploration continued, including many seasons of drilling from the 1970s through the 1990s. Imperial Metals acquired the properties in 2006, continued with extensive drill programs in 2007 and 2008 to define the deposit, including its underground extension. This deposit became feasible to mine with access to power provided by the construction of the Northwest Transmission Line and Hwy 37 Transmission Line extension. Construction of this surface mine began in May 2012; it was completed in late 2014 at a cost of $669 million.
Red Chris is owned and operated by Red Chris Development Company, a subsidiary of Imperial Metals Corporation. The mine currently processes 30,000 tonnes per day. In 2016 it produced 83,614,000 pounds of copper, 47,088 ounces of gold and 190,624 ounces of silver. Based on current production rates, proven and probable reserves allow mining to continue until 2043.
Mining Method: Surface mining at Red Chris uses conventional open pit methods and is occurs in two zones in one pit. Blasted rock is loaded into haul trucks using an electric shovel, a hydraulic shovel or a front end loader. Trucks haul the ore to a crusher located next to the mill. Waste rock is hauled to a designated waste rock dump that stores either non-acid generating rock or potentially acid-generating rock which must be managed differently at the end of the mine life.
Mineral Processing: The ore runs through a primary gyratory crusher near the pit and is conveyed to a stockpile near the mill. It is conveyed into the mill building where is passes through a SAG, ball and pebble mill that pulverize the ore to fine sand. It exits the final mill as a slurry that is piped to flotation cells. In the cells (or tanks) the copper/gold concentrate floats to the surface. It is collected and cleaned in a sequence of float cells before being piped to a thickener cell and on to pressure filters that reduce water in the concentrate to 8%. The concentrate is stored in concrete bins until being trucked to port. Tailings from the flotation cells are sent to devices (cyclone) that separate coarse tailings from the fine ones. De-pyritized coarse tailings are used in construction of the tailings impoundment dam while the fines are deposited in the tailings impoundment.
Markets: Concentrate from Red Chris Mine is trucked to the Port of Stewart. At Stewart Bulk Terminals it There it is loaded onto bulk carriers and transported to smelters in Asia.
Community and Employment: Red Chris Mine employs 370 people. Half are from surrounding communities; over 35% are First Nations. A portion of the workforce travels in and out via charter from Vancouver airport to Dease Lake airport, and from there by shuttle bus to the mine. All employees who work at the mine stay in camp for the duration of their shift. Each has a private room, snacks and three meals daily. The camp also has a commissary, recreation facility, games room, fitness room, TV room, areas for socializing, and a room with public phones.
Environmental Considerations: Red Chris is located in the Todagin upland plateau along the northern margin of the Skeena Mountains. Before exploration began the main land uses were wildlife habitat that supported hunting, guide outfitting, trapping, and outdoor recreation. The main goal of the reclamation plan is to return areas disturbed by mining to their pre-mining land use and capability.
To compensate for fish habitat lost by construction of the tailings impoundment the mine made improvements to nearby Snapper Creek, replacing two culverts under Hwy 37 with a single span bridge so fish could easily use upstream habitat.
During operation the main consideration is protection of natural drainages. All water that is used or moves across the surface on the site is collected and directed to the tailings impoundment; this water is recycled and used in the mill again and again. During high seasonal precipitation or runoff there are also methods to collect extra surface water and groundwater seepage.
Reclamation at Red Chris will be ongoing during operation, for example, replanting areas that are no longer in use. When the mine closes the plan includes: 1) capping all waste rock dumps with till (soil) collected and stockpiled during construction and re-establishing vegetation on them; 2) allowing the pit to fill with groundwater; 3) leaving the tailings impoundment as an open pond to keep potentially acid generating sand under water forever, with the dams and pond edges revegetated; 4) removing all buildings and other structures, and regrading and replanting; 5) removing all structures placed to change water courses, like culverts, to re-establish the natural water ways; 6) removing, grading and replanting all mine roads not required for long term monitoring.