Highland Valley Copper Mine, British Columbia, Canada

Highland Valley copper / molybdenum mine is located 75km southwest of Kamloops, British Columbia, Canada. The Valley pit has yielded more than 1,100Mt of ore in its lifetime.

Highland Valley Copper was created as a partnership between Rio Algom and Cominco in 1986 to combine the Bethlehem and Lornex mines. Following the merger between Teck and Cominco in 2001, the 2000 takeover of Rio Algom by Billiton and Billiton's subsequent merger with BHP, the mine was then majority owned by Teck Cominco (63.9%) and BHP Billiton (33.6%). At the beginning of 2004, Teck Cominco exercised its pre-emptive rights over BHP Billiton's holding when the latter put it up for sale, and is now 97.5% owner of Highland Valley.

In both 2004 and 2005, mill throughput exceeded 50Mt/y, with the operation achieving a record average throughput of 138,800t/d in 2005.

GEOLOGY

Highland Valley is a low-grade (0.4% Cu) porphyry copper-molybdenum deposit associated with the younger intrusive phases of the early to mid-jurassic, calc-alkaline Guichon Creek batholith.

As of the end of 2005, proven and probable ore reserves totalled 318Mt grading 0.43% copper and 0.008% molybdenum. Mineral resources added a further 151.9Mt at 0.37% copper and 0.005% moly.

OPEN-PIT MINING

Open-pit mining is used in both the Lornex and Valley pits, with around 90% of the ore coming from the Valley pit. Three computerised Bucyrus 49R drills prepare blast hole patterns while nine P&H 4100A 37 yd³ electric shovels load ore into a fleet of Komatsu haul trucks for transport to in-pit crushers. In 2001, eight of the 170t-capacity trucks were replaced by six new 215t haulers. Additional support is provided by three water trucks, eight road graders, eight tracked bulldozers, three rubber-tyred bulldozers and one front-end loader.

The mine uses two semi-mobile in-pit crushers to minimise haul distances. Several kilometres of conveyors carry up to 12,000t/h of crushed ore to three stockpiles at the Highland mill. Pit operations are monitored and controlled by a Modular Mining Systems computerised dispatch system designed to maximise mine production. In addition minute-by-minute mapping is achieved by combining GPS navigation and survey with GIS mapping techniques.

ORE PROCESSING

The Highland mill, the world’s third largest copper concentrator, was constructed in the late 1980s by combining the original Lornex and Highmont mills. The complete Highmont mill was moved by road 10km from its former site to a new position adjacent to the Lornex plant.

The crushed ore enters two grinding stages in five parallel grinding lines incorporating two fully-autogenous mills, and three semi-autogenous (SAG) mills grinding a total of 5,400t/h. The second stage consists of eight ball mills reducing ore to sand-sized particles which feed the flotation circuits. The primary flotation stage extracts copper and molybdenum from the slurry before copper and molybdenum are separated. The molybdenum concentrate is mixed with a leaching brine in sealed, pressurised, heated vessels where residual copper is dissolved, leaving a high-grade molybdenum concentrate. Lastly, the copper and molybdenum concentrates are filtered and dried in gas-fired driers for shipping. Three 1m-diameter pipelines take the tailings 7km overland from the mill to the Valley tailings pond.

CONCENTRATE TRANSPORT

Copper concentrate is transported in bulk 40km to the rail yard at Ashcroft, then by rail to north Vancouver and finally by ship to overseas smelters. The molybdenum concentrate is packaged on site for shipment.

ENVIRONMENT

In 1997, Highland Valley Copper was presented with the 1996 British Columbia Reclamation Citation Award in the metal mining category for its outstanding achievement in reclaiming 1,000ha and planting 700,000 native trees and shrubs. Work to establish fish stocks in different water bodies on the property is continuing to be successful.

PRODUCTION

Output in 2004 totalled 170,300t of copper in concentrates and 4,850t of molybdenum in concentrates from 50.6Mt of ore milled. Including waste rock, the total materials-handling requirement was 65.8Mt.

In 2005, ore production remained at 50.6Mt, with the head grade rising slightly to 0.39% copper. Higher recoveries helped boost copper production to 179,000t, plus 2,860t of molybdenum. The mine was the largest single contributor to Teck Cominco’s operating profits in 2005, at US$613m.

THE FUTURE

In early 2007, Teck Cominco committed C$300m to extending the mine’s life to 2019, with further expansion to the Valley open pit and renewed production from the Highmont pit, which has higher moly grades but lower copper than at Valley. This will release a further 247Mt of ore containing some 680,000t of copper and 9,500t of moly for production over a six-year period from 2013 to 2019. The company had earlier budgeted C$190m to extend the mine’s life from 2008 to 2013, involving increased waste stripping in the Valley pit.

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