Hudbay Minerals reported in May that its Constancia project in Peru achieved commercial production in late April,
seaborne copper concentrate shipments from the mine began a few weeks later, and both the mine and concentrator
were operating at or above design capacity. (Photo courtesy of Hudbay Minerals)

Throughput at the Constancia plant averaged 78,635 mt/d during April, just short of design capacity of 80,000 mt/d. “The ramp up has met management’s expectations with regards to throughput, recovery, and product quality,” Hudbay stated in its report of its first-quarter 2015 results. “The plant is performing as designed and throughput has occasionally exceeded design capacity due to favorable ore characteristics, with peaks of more than 90,000 mt/d. Copper recovery in April averaged a little more than 65%, which is in line with ramp-up design and expectations.”

Constancia production of copper concentrates is planned to average 82,000 mt/y over a mine life of 22 years. Project development capital totaled about $1.7 billion.

Hudbay’s focus in the initial stages of ramp up at Constancia was on ore throughput, with an aim to meet saleable concentrate specifications. In May, it shifted its focus to increasing copper recovery, while maintaining throughput and concentrate quality. A key component of improving copper recovery was expected to be a recently started concentrate regrind circuit.

Hudbay continues to expect Constancia operations to achieve steady-state design and feasibility level recoveries of copper in the fourth quarter of 2015. Assuming that the copper ramp up would continue as planned, Hudbay was planning to begin ramping up Constancia’s molybdenum concentrate separation circuit during the second quarter of 2015.

Constancia is a conventional surface mining operation. As of late April, the performance of its mining fleet was approaching design expectations. A mine dispatch system had been installed and was providing the necessary data to further optimize the fleet. Mine reconciliations were indicating that the long-term model was supported by field measurements. Management was confident that grade and geology characteristics were well represented in the long-term plan.

Constancia project development benefitted from access to existing roads, rail, a deep-sea port, and a power substation that support mine-site operations and the movement of copper concentrate from the site. Hudbay has secured 10-year port access and power supply agreements, as well as a 15-year tax and fiscal stability agreement, with the government of Peru.

Constancia’s proven and probable reserves totaled 620 million mt grading 0.32% copper, 92 g/mt molybdenum, 0.056 g/mt gold, and 3.07 g/mt silver as of January 1, 2014.