The Gunnison copper project, in southern Arizona, remains on schedule for first copper production before the end of the year, TSX-listed Excelsior Mining confirmed on Thursday, reporting that the drilling of the production wellfield had been completed.
A total of 41 production wells had been successfully drilled, toa depth of nearly 400 m each. The company said that all wells were open within the copper orebody.
The developer would complete the installation of the necessary infrastructure and instrumentation, including stainless steel pumps in the recovery wells, in the coming weeks.
“We are rapidly closing in on the completion of the entire construction process,” commented COO Roland Goodgame.
“The most critical component of our construction schedule has always been the drilling of the production wellfield; this key milestone has now been completed, thereby allowing us to remain on track for copper production later this year.”
Working in parallel to the drilling of the injection and recovery wells, 16 compliance and monitoring wells surrounding the production wellfield had also been completed.
Further, the primary header station, which contained piping connections and the controls needed to monitor and adjust flow rates, had been constructed and was ready for commissioning.
The Gunnison project is permitted to produce 125-million pounds a year of copper cathode.
The feasibility study projected an after-tax net present value of $807-million and an internal rate of return of 40%, using a $2.75/lb copper price and a 7.5% discount rate.
Excelsior's share price gained 3% to close at C$0.95 a share on Thursday.