The leak, since plugged, caused extensive flooding in the milling and primary crusher areas. Hardest hit was the crusher’s electrical switchgear, which suffered “significant damage.” Milling resumed about a week after the leak, with feed sourced from stockpiled ore, supplemented with ore run through portable crushers. Repairs to the switchgear took a little longer, but the power was reconnected on Feb. 15.
The mine’s open-pit and underground mining operations were not affected.
“I am pleased to report that operations are back in full swing here at Lac des les and that there was no environmental impact as a result of the leak,” said NAP chief executive Jim Excell in a statement. “Again, our team here has done an excellent job in managing this situation, while ensuring that the repair process was completed as quickly and seamlessly as possible.”
The latest crusher shutdown comes on the heels of an unscheduled shutdown in early January to replace the mainframe component. The work was done after the milling circuit suffered through intermittent stoppages throughout December, owing to operational issues with the crusher.
Those interruptions in the crushing cycle clipped fourth-quarter mill throughput and availability. The associated need to process stockpiled ore also pushed feed grades lower, and saw many chute blockages due to frozen rock chunks.
In the end, the mill managed to squeeze 36,833 oz. palladium out of 1.1 million tonnes of ore averaging 1.47 grams palladium per tonne, for an average recovery rate of 70.7%. That compares with the 39,532 oz. recovered from 1.3 million tonnes of similar-grade ore during the third quarter, when recoveries averaged just 62.9%. The improved recovery rate reflects ongoing improvements to the flotation circuit.
Overall, production in 2005 slipped by 43% from a year earlier to 177,167 oz. The average recovery rate rang in at 69.6%.
Looking ahead, palladium production is expected to increase in 2006 as the mine’s underground operations kick in during the first quarter. Underground mining will target the Main High Grade zone beneath the ultimate pit floor at a rate of 2,000 tonnes per day. The ore, averaging 6.62 grams palladium, will be combined with 13,500 tonnes per day from the open pit to yield a feed averaging 2.33 grams palladium per tonne. The underground operation will run for at least five years.
At the end of 2004, underground reserves stood at 3.5 million tonnes running 6.62 grams palladium, 0.4 gram platinum and 0.3 gram gold, plus 0.07% copper and 0.08% nickel, based on a cutoff grade of 4.5 grams palladium.
Another 600,000 tonnes of indicated resources grade 7 grams palladium, 0.4 gram platinum, 0.3 gram gold, 0.06% copper and 0.07% nickel. Inferred resources come to 5.4 million tonnes of 6.1 grams palladium, 0.3 gram platinum, 0.3 gram gold, 0.07% copper and 0.12% nickel.
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