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Mount Milligan restarting after freeze-up halted operations

After being shut down for close to six weeks, the Mount Milligan mine is ramping up its operations.

The mine was shut down December 27 because it was having trouble getting enough water. Drier-than-normal conditions from March to August together with a limited amount of spring snowmelt resulted in lower than expected water volumes at the mine’s tailings storage facility. Added to that, cold weather around Christmas froze what water it had.

It sought an amendment to its Environmental Assessment to allow it to pump water from nearby Philip Lake.

The company has initiated restart of mill operations at partial capacity.

At this time, the mill is utilizing one ball mill to minimize water requirements, according to a company news release. During the restart phase, the company anticipates a ramp-up period and there may be periodic commissioning downtime.

Mill operations are expected to achieve sustainable mill throughput levels of approximately 30,000 tonnes per day by mid-February.

During the recent shutdown the company completed a number of steps to increase the flow of water into the tailings storage facility from which the Mount Milligan mill draws all of its water requirements to supply milling operations. Such steps included adding pumps to existing water wells, increasing pump sizes to increase the flow rate, and drilling additional wells. Current make-up water sources for the tailings pond are from normal surface run-off, groundwater wells internal to the facility, and from base underdrain towers that access process water underlying the tailings pond.

The company expects to restart the second ball mill in April, returning mill operations to full capacity, when additional fresh water becomes available from surface run-off after the spring melt. The return of mill operations to sustainable levels, on one or both ball mills, is dependent on the performance of the make-up water sources noted above and the overall water balance in the tailings pond.

As a further longer-term mitigation measure, the Company has now received an amendment to Mount Milligan’s Environmental Assessment Certificate to allow pumping of water from nearby Philip Lake and has received the additional related permits. The Company expects to commence drawing water from Philip Lake by the end of February.

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