Copper Mountain Mining has released a new technical report for its open-pit Copper Mountain mine in southern British Columbia. The report includes a new life-of-mine plan and a proposed mill expansion to 65,000 tonnes of ore per day, which would boost the mine’s estimated net present value to just over US$1 billion.

The company holds a 75 per cent interest in the mine – with Mitsubishi Metals holding the remaining 25 per cent – where it is currently conducting a mill expansion to 45,000 tonnes per day, up from 40,000 tonnes per day. By expanding the mill’s throughput to 65,000 tonnes a day, Copper Mountain says the mine will have an estimated after-tax net present value of US$1.01 billion with an eight per cent discount rate, assuming prices of US$3.15 per pound of copper, US$1,700 per ounce of gold and US$22 per ounce of silver. This represents a more than 60 per cent increase from the mine’s 2019 technical report, which estimated a net present value of US$619 million with an eight per cent discount rate.

According to the company, the expansion will not only increase throughput but will reduce operating costs, improve flotation performance and decongest concentrate dewatering. The initial capital costs are estimated at US$148 million with total sustaining capital for the life of mine estimated at US$255 million, according to the report.

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“The [expansion]... clearly underscores the mine's quality, and our team's ability to potentially grow reserves and value further,” Copper Mountain president and CEO Gil Clausen said. “In two years, we have more than doubled the mine life, grown the mine's productive capacity, increased net asset value and significantly decreased cash costs. Following the completion of this 2020 technical report, we will further refine the capital estimates of this project in preparation for a development decision.”

While the current mill expansion to 45,000 tonnes of ore processed per day includes adding a third ball mill to its current two, the new mill expansion plan includes installing a fourth ball mill and a regrind Metso Vertimill. The company will also replace the mine’s existing SAG mill with a high pressure grinding roll circuit, which will reduce unit milling costs by an estimated 25 per cent from the current expansion. 

Once completed, Copper Mountain is expected to mine a total of 400 million tonnes of ore, producing two billion pounds of copper, 978,000 ounces of gold and 6.7 million ounces of silver over a 21-year mine life, an increase of one year. The company also stated that it believes that future exploration could potentially further extend the mine’s life.

If undertaken, construction on the new expansion plan is estimated to finish by late 2023 and be working by early 2024.