Trevali reduced its production guidance for its Caribou mine, pictured, after encountering challenging rock conditions that endangered the safety of workers. Courtesy of Trevali Mining

Trevali Mining is downgrading production at its Caribou zinc-lead-silver mine in New Brunswick as a result of challenging rock conditions.

Trevali said in a Tuesday press release that, the state of the rock conditions at Caribou changed to the point that work could not be continued at its current pace without putting the safety of the mine’s workers at risk.

A shift from cemented rock fill to unconsolidated fill on the hanging wall rock forced the company to slow the mining rate while it explores engineering solutions to accelerate production from the fourth quarter of this year through to next year.

As a result, Trevali has revised its 2018 production guidance for the mine. Silver production has remained unaffected, but zinc production has shrunk 17 per cent – 70 to 75 million pounds, down from 86 to 90 million pounds – and lead production has been cut by 12 per cent, to a range of 23 to 25 million pounds, down from 27.1 to 28.4.

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Operating costs at the mine have also grown as a result of the slowdown, increasing to US$63 to $69 per tonne from US$55 to $61 per tonne previously.

“It is incredibly disappointing that the Caribou mine has been forced to slow down, however this was a necessary step in order to ensure the safety of our workforce and enhance the long-term economics of the mine,” Trevali president and CEO Mark Cruise said in a statement. “This strategic direction was made with a view of establishing a stronger foundation for the operation to deliver on expectations in 2019 and beyond.”

Trevali said it is currently on track to reach production guidance benchmarks at its Peruvian Santander and Namibian Rosh Pinah mines, with its Burkanese Perkoa mine exceeding its guidance for the year, which the company says will allow it to meet its initial consolidated zinc production guidance for the year.

Caribou currently reports proven and probable mineral reserves of 5.22 million tonnes with grades of 6.34 per cent zinc, 2.37 per cent lead, and 71.20 grams per tonne of silver. The mine officially started production in 2016 and has a five- to six-year life.