VANCOUVER (miningweekly.com) – Base metals producer Taseko Mines has received approval to proceed with construction of the first phase of its controversial Florence in situ copper project, in Arizona.

The US Environmental Protection Agency has issued a final underground injection control (UIC) permit for Taseko to proceed with the pioneering copper extraction method, effective from January 31, 2017.

The Phase 1 test facility will serve to optimise the copper recovery process and demonstrate its environmental integrity and reliability.

"Permitting any industrial project is a lengthy and challenging process, which is why the receipt of the UIC permit is a major milestone achieved by the company. There is a possibility that opposing parties will attempt to appeal the UIC permit, similar to the challenge made to the previously granted aquifer protection permit (APP), but we expect that the regulatory authorities will successfully defend their thorough process," president and CEO Russell Hallbauer stated.

Vancouver-based Taseko acquired the project through the $78.9-million takeover of Curis Resources and its in situ copper recovery and solvent extraction and electrowinning Florence project, in central Arizona, in 2014. The project had in 2013 received a final amended APP from the Arizona Department of Environmental Quality, authorising the construction, operation and closure of a 24-well mine.

Local town officials and residents opposed to the project fear contamination of the local water supply. The operation will mine underground copper by dissolving it with a sulphuric acid solution and pumping it to the surface for extraction from the solution.

The project has now successfully met all its regulatory obligations at both the state and federal levels. Including the UIC permit, and the APP, the project has received 19 permits and authorisations.

According to Taseko, the Florence deposit contains 2.4-billion pounds of copper in 340-million tons of probable reserves grading 0.358% copper, and represents a pre-tax net present value, at a 7.5% discount rate, of $725-million, with an internal rate of return of 36% using a long-term copper price of $2.75/lb. 

The project is expected to produce copper at direct operating costs of $0.80/lb and allows the copper to be recovered using a water-based solution to manufacture London Metals Exchange Grade A copper cathode.

Once commercial production is reached, the project will produce an average of 75-million pounds a year over 20 years.