The firm said after successfully completing commissioning and ramp-up of phase I, it will go into commercial production on February 1.
This is based on plant performance reporting over 85% of planned throughput capacity, copper recoveries above 80% and concentrate grades of approximately 20% Cu.
Optimisation work continues whilst expansion projects are under construction, with phase I and phase II into one project.
Numis Securities said: “This should maximise synergies and potential result in further capex savings and a shorter delivery schedule.”
The merger of the expansion projects should have some tangible cost benefits plus commissioning of the expansion should start ahead of the original plan of mid-2016, it added.
Alberto Lavandeira, chief executive, said: “Achieving commercial production is a very significant milestone for the company and all credit must be given to the teams participating in the fast-track development of the project following receipt of the key permits in early 2015.”
Shares were 1.8% higher at 97p on Friday.