With ongoing success at the test facility of the Florence copper project, in the US, dual-listed Taseko Mines has awarded the basic engineering contract for a commercial facility to professional services group Stantec.

In the last nine months, Vancouver-based Taseko has commissioned a 24-hole test wellfield consisting of injection, recovery and monitoring wells, while ramping up the solvent extraction and electrowinning plant to design capacity.

The process included the initial leaching period where hydraulic control of solutions 800 ft to 1 200 ft underground, in the orebody, remained compliant with environmental guidelines. At the same time, the process of recovering copper-rich solutions from the orebody has started.

“With steady-state operation now achieved, our focus has turned to testing different wellfield operating strategies, including adjusting pumping rates, solution strength, flow direction, and the use of packers in recovery and injection wells to isolate different zones of the orebody. Sweep efficiencies in the wellfield continue to outperform our expectations. Our technical team is using physical and operating control mechanisms to adjust solution chemistry and flow rates and is successfully increasing copper concentration in solution.

“The main recovery well is now producing copper in solution at an annualised rate of approximately 600 000 lb/y, and the expectation is for steady improvement, as the well matures. We are gaining valuable operating experience that will be used to reduce the ramp-up period for commercial wellfield operations,” said CEO Russell Hallbauer.

Taseko is also actively engaged with the Environmental Protection Agency and the Arizona Department of Environmental Quality to advance commercial operating permits, which are expected to be granted in the summer of 2020.

The Florence project will be one of the lowest-cost operations globally, when in commercial operation, with a cash cost of $1.10/lb of copper. Florence will produce an average of 85-million pounds a year of copper, increasing Taseko’s attributable yearly copper output to about 190-million pounds a year.

The project boasts a net present value of C$1-billion.