TORONTO (miningweekly.com) – Base metals producer Capstone Mining is on track to meet its 2015 production guidance and to beat its C1 cash cost guidance despite a 16% drop in copper output for the three months ended September.

The TSX-listed company, with mines in Canada, the US and Mexico, on Tuesday reported consolidated output of 22 100 t of copper for the three months ended September 30 and 66 900 t of copper in concentrate and cathode in the year-to-date periods, with additional by-products of zinc, molybdenum, lead, silver and gold.

"Production for the third quarter met our expectations and we remain on track to meet our overall 2015 production guidance, with Minto [in Canada] operating above expectations for the quarter and Pinto Valley [in Arizona] and Cozamin [in Mexico] overcoming earlier production challenges. We are particularly pleased that the operational improvements at Pinto Valley are starting to be realised, achieving a monthly throughput record for Capstone in September,” president and CEO Darren Pylot stated.

At Pinto Valley, production was on plan for the quarter and remained on track for the year with better-than-predicted block grades and recoveries continuing to offset throughput. In the third quarter, throughput was negatively affected by six days of downtime in August for repairs to the primary crusher.

Excluding the August down days associated with a single incident, throughput for the operating days in the quarter averaged 49 800 t/d and the month of September averaged 52 400 t/d, bettering the 52 000 t/d throughput target. The run rate exiting the quarter was strong, with throughput averaging 56 500 t/d for the last ten days of September and more than 55 300 t/d for the first ten days of October. The current mine plan called for the copper grade to increase to 0.38% for the fourth quarter.

At Cozamin, activities related to dilution control produced a significant improvement in grade for the quarter and recoveries returned to planned levels. Throughput improved each month during the quarter as the mine made good progress in catching up development and long-hole inventory shortfalls carried forward from earlier in the year. 

At Minto, grades and recoveries were on plan for the quarter as the mill returned to solely processing underground and stockpiled ore, while transitioning to the next openpit mining area. Throughput, however, significantly outperformed, allowing production to continue above plan in the third quarter.

The Yukon Water Board had issued the final water-use licence on August 5, with stripping of the Minto North openpit starting immediately. Stripping of Minto North was on schedule for first ore to be processed at the mill starting in December, with high-grade ore starting in the second quarter of 2016. The mill would continue to process underground and stockpiled ore while stripping was taking place.

Capstone's production guidance of 90 000 t of copper remained intact, with C1 cash cost lowered to between $1.95/lb and $2.05/lb of payable copper produced, net of by-product credits and selling costs, down from the $2/lb to $2.10/lb originally planned for 2015.