Denison sees increasing prospects for Canadian ISL

The past year has seen the company begin the environmental assessment process for Wheeler River, and in December it received a positive project scoping decision from the Canadian Nuclear Safety Commission, Cates said. In addition, Denison last year completed a successful ISL field test programme to validate the permeability of the Phoenix orebody, which had been identified as the most significant technical risk for the Phoenix ISL operation. The programme included the completion of the first commercial-scale wells in the history of the Athabasca Basin intended for ISL mining. "The results from this test work show significant hydraulic connectivity within the test areas of the Phoenix orebody and have confirmed our ability to achieve bulk hydraulic conductivity values, in a commercial scale well," Cates said.

In addition, the company in February of this year announced results from a specialised core leach test showing uranium concentrations up to four times those used in the pre-feasibility study for the Phoenix operation. A metallurgical test programme using the mineralised drill cores recovered during the installation of test wells during the 2019 field test programme is ongoing, and will include core leach tests, column leach tests, bench-scale tests and metallurgical modelling.

"Taken together, these results have meaningfully increased our confidence in the application of ISR mining at Phoenix.  Today, the prospect of successfully bringing ISR mining to the Athabasca Basin is higher than it has ever been," Cates said. ISR - or in-situ recovery - is another term for ISL mining.

Wheeler River is described by Denison as the largest undeveloped uranium project in the eastern portion of the Athabasca Basin region, in northern Saskatchewan. It includes combined indicated mineral resources of 132.1 million pounds U3O8 (50,812 tU), plus combined inferred mineral resources of 3.0 million pounds U3O8. The project is host to the high-grade Phoenix and Gryphon uranium deposits, discovered by Denison in 2008 and 2014, respectively, and is a joint venture between Denison (90% and operator) and JCU (Canada) Exploration Company Limited (10%).

A pre-feasibility study completed in late 2018 considers the potential economic merit of developing the Phoenix deposit as an ISL operation and the Gryphon deposit as a conventional underground mining operation: ISL methods are only applicable to sandstone-hosted uranium deposits located below the water table in a confined aquifer, and the Gryphon deposit is not suitable for recovery by this technique.  Taken together, the project is estimated to have mine production of 109.4 million pounds U3O8 over a 14-year mine life.

According to World Nuclear Association, around half of the world's uranium is now produced using ISL mining methods. The technique has not as yet been used for uranium production in Canada.