Midtier copper miner Taseko Mines expects to tick a major permitting box for its Florence Copper project, in the US, this week.

The company says it has been informed that the Arizona Department of Environmental Quality (ADEQ) will issue the draft aquifer protection permit (APP) for the Florence commercial production facility on Thursday.

The APP is one of two key permits required to advance the project to commercial production.

"The issuance of this important permit is a confirmation by the state regulator that the Florence Copper in-situ mining process is environmentally safe. We have proven this over the past 18 months while operating the test facility within all the stringent conditions set out in the current permit,” comments Taseko CEO Russell Hallbauer.

“We fully expect that following the 30-day public comment period, the ADEQ will be positioned to quickly issue the final permit."

The company has operated a test facility, which includes 24 injection, recovery and monitoring wells and an solvent extraction and electrowinning plant, for 18 months.

Hallbauer says the test facility has successfully demonstrated that Florence can produce high-quality copper cathode, within the stringent environmental guidelines of its permits. It also confirmed the project economics.

"Many of the modelled assumptions have been validated and we have used the data to develop strategies for solution chemistry, flow rates, reverse flow and the use of well packers for targeting solution flows. The hydrogeological model has been updated using the data collected over the past 18 months and is being used to refine our operating plan for the commercial phase," continues Hallbauer.

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.