The project, first announced in 2018, included the installation of a refurbished mill, electrical substation with 1,250kVa capacity, and a secondary cluster to permit a finer grind size option so it may achieve a 6% boost in recoveries from 80% to 86%.

The ramp up of production is now under way and will take the mine and mill from 3,000t/d to 3,600t/d this quarter and, ultimately, 5,000t/d by the middle of 2020. Company president and CEO Igor Gonzales said its first increase goal is on track due to the early completion of the Piedras Verdes mill.

"The expansion at Bolivar represents the first of many exciting milestones for Sierra Metals in 2019 as we continue toward our goal of creating additional value to the company and its shareholders," he said.

"With increased production capacity at Bolivar mine, we remain focused on our brownfield exploration programme and the importance of continuing to add to our reserves and resources. With the discovery of future resource additions, we believe that this expansion will allow for potential new copper pounds discovered to be incorporated into production plans earlier than if the company had maintained a lower capacity level."

Sierra Metals operates three total mines in Peru and Mexico - Bolivar in Chihuahua as well as Cusi and Yauricocha.