The Copper Mountain mine is an open-pit copper mining operation located in British Columbia, Canada. The mining property is under shared ownership between Copper Mountain Mining (75%) and Mitsubishi Materials (25%).
The mine produces copper concentrates along with silver and gold as by-products. It produced approximately 87.2 million pounds (Mlbs) of copper equivalent in 2019.
Although the first exploration activities at Copper Mountain were started in the late 1890s, Granby Consolidated Mining, Smelting and Power Company (Granby) acquired the property in 1923 and continued underground production until 1957.
Newmont Mining began open-pit operations at the site in 1968 that continued through 1996, while Copper Mountain Mining acquired the property in 2006 and initiated production in August 2011.
An expansion project to add a third ball mill to increase the mill capacity from 40kt/d to 45kt/d is currently underway with commissioning expected in late 2021.
In November 2020, Copper Mountain released a pre-feasibility study (PFS) to further expand the milling capacity to 65kt/d.
Project location and geology
The Copper Mountain mine is located approximately 2km south of Princeton and 180km east of Vancouver, in British Columbia, Canada. The mining property covers a total area of approximately 6,263 hectares.
The Copper Mountain mine is part of a northerly trending Mesozoic tectonostratigraphic Quesnel terrane, underlain by the volcanic, sedimentary, and coeval intrusive rocks of the Late Triassic, Nicola group.
The copper property is located on the eastern volcanic belt of the Nicola Group with intrusive Early Jurassic alkalic dykes, sills, irregular plugs, and zoned plutons of the Copper Mountain suite.
Mineralisation and reserves
Copper Mountain is an alkalic porphyry deposit hosted in structurally controlled, multidirectional veins and vein stockworks, featuring peripheral disseminations.
The mineralisation is subdivided into four types while the alterations occur in three main types defined as hornfels, sodic, and potassic.
The total proven and probable ore reserves at the Copper Mountain deposit were estimated to be approximately 410 million tonnes (Mt) grading 0.24% copper (Cu), 0.76% silver (Ag), and 0.11% gold (Au), as of September 2020.
The stockpile reserves were estimated to be approximately 52Mt grading 0.15% Cu, 0.45%Ag, and 0.04% Au.
The Copper Mountain mine uses the conventional open-pit methods of drilling, blasting, loading, and hauling.
The mining operations are carried out in 15m benches with varying slope angles of the pit walls based on lithology, alteration, and local ground conditions. The bench face angles vary between 70 and 73 degrees, while the berms range from 9m to 14m with the ramps up to 33.5m-wide.
The mining fleet comprises two 42m3 capacity electric shovels, two diesel shovels, 24 units of 220t haul trucks, and five drills.
The run-of-the-mine (ROM) ore undergoes primary and secondary crushing in a gyratory and cone crusher respectively.
The grinding circuit comprises a semi-autogenous grinding (SAG) mill operating in a closed circuit. The mill oversize is introduced into an FLS XL900 cone crusher while the undersize reports to two ball mills operating in parallel.
The ball mill product is introduced into a rougher flotation circuit to produce a rougher concentrate which is then pumped to a regrind mill for further liberation.
The regrind cyclone overflow is pumped to high column cells to produce the final copper concentrate.
A flash flotation circuit was installed in August 2018 to process the coarse liberated material and produce the final copper concentrate. A new cleaner flotation circuit with direct flotation reactor (DFR) cells was also commissioned in July 2019 to process flotation column concentrate.
The final concentrate product is introduced into the dewatering circuit comprising a high rate concentrate thickener, a concentrate storage tank, and a 62 plated filter press to produce a concentrated filter cake. Gold and silver are recovered as by-products in the final copper concentrate.
The filter cake concentrate is stored prior to being loaded on to trucks for transport to the port in Vancouver for export.
Access to the mining area is available from the town of Princeton via an 18.4km-long paved road and a 2.6km-long gravel road.
The mine receives power supply through a 138 kV transmission line from the Nicola Substation near Merritt, under an electricity supply agreement (ESA) with BC Hydro.
The water requirement for the project is pumped from the nearby Similkameen River and is also recycled from the tailings management facility (TMF).
Gisborne Industrial Construction was engaged as the general works contractor for the project in September 2009.
The feasibility study published under Copper Mountain Mining in July 2008 was prepared by Hatch.