Excelsior Mining reported in early February that, following the first month of mining operations, it has collected a significant amount of data that will support optimization programs that are currently being implemented at its Gunnison in-situ recovery (ISR) copper project in Cochise County, Arizona, 65 miles southeast of Tucson.
Included in these programs are improved preventive maintenance to limit pump and wellfield downtime; retrofitting of injection wells with pumps, allowing them to be used as recovery wells when needed; and reconfiguration of wellheads and related piping to allow for both injection and recovery operations in each well. This latter addition will make the wellfield entirely reversable in terms of fluid flow, thereby allowing for greater flexibility during operations.
Excelsior has decided to implement these changes during the ramp-up period to assist with production optimization. These changes are not material in terms of capital outlays, but the work is expected to push first copper production into the second quarter of 2020.
Fluids recovered from ISR operations will be treated through existing SX-EW processing facilities at the previously operated Johnson Camp mine a little more than a mile from the wellfield. The plant will produce copper cathode sheets, with product sales now expected to begin during the second quarter of 2020.
The availability of the Johnson Camp processing facilities allowed the Gunnison project to come in at low initial capital expenditures of $49 million.
The Gunnison project is targeting an initial production rate of 25 million pounds per year (lb/y) of copper, expanding to eventual production of 125 million lb/y. Mine life is projected at 24 years at all-in sustaining costs of production of $1.33/lb of copper produced.
Excelsior President and CEO Stephen Twyerould said, “Our initial copper recoveries are highly encouraging, and the implementation of these improvement programs keeps us focused on achieving long-term, low-cost copper production as soon as possible. We remain absolutely confident in our capacity to deliver low-cost copper production while maintaining our commitment to safety and the environment.”