Centerra Gold reported that its Mount Milligan operation in British Columbia, Canada, initiated the restart of its mill operations at partial capacity on February 5. The mill is using one of three ball mills to minimize water requirements. 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 tons per year (t/d) 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 (TSF) from which the Mount Milligan mill draws all of its water requirements to supply milling operations. These steps included adding pumps to existing water wells, increasing pump sizes to increase the flow rate, and drilling additional wells. Current makeup water sources for the TSF are from normal surface run-off, groundwater wells internal to the TSF, and from base underdrain towers that access process water underlying the TSF.
The company said it 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 company said it has received an amendment to Mount Milligan’s Environmental Assessment Certificate to allow pumping of water from a nearby lake (Philip Lake) and has received the additional related permits. Centerra said it expects to commence drawing water from Philip Lake by the end of February.