The Toronto-based company said the step was part one of a staged expansion plan outlined in a July 2018 preliminary economic assessment aimed at increasing the production rate to 5,000t/d by 2020.

Installation of a refurbished mill, a 1,250kv electrical substation, secondary crusher and a hydrocyclone cluster that allows for finer grind sizes and is expected to provide a 6% increase in copper recoveries from 80% to 86%, have all now been completed.

"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," CEO Igor Gonzales said.

He added the expansion would result in reduced unit costs at Bolivar.

"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." 

Teh company also operates the Cusi mine in Mexico and the Yauricocha mine in Peru.

Sierra, with a market capitalisation of C$340.73 million, saw its shares gain 2.4% in Toronto Wednesday to C$2.14, before falling back to $2.10. The stock has a 12-month high of $3.