Canada’s Denison Mines Corp is going to press ahead with its evaluation of in-situ recovery (ISR) mining of an Athabasca Basin uranium resource on behalf of the Midwest Joint Venture after reporting “positive” results from a concept study.
Denison has 25.17% of the JV with French nuclear fuel cycle company, Orano Group, which owns the balance.
Midwest, near the Denison and Orano-owned McClean Lake uranium mill in the eastern part of the Athabasca Basin region in northern Saskatchewan, has an exploration and development history going back more than 50 years. Orano Canada previously examined openpit mining of the main deposit.
The JV area has two outlined deposits: Midwest Main and Midwest A. Both are said to have high-grade cores of mineralisation surrounded by lower-grade, fracture-controlled “envelopes” of mineralisation mostly contained in sandstone.
Midwest Main has an estimated 453,000 tonnes grading 4% U308 indicated and 793,000t at 0.66% inferred in a zone about 600m long, 10-100m wide, with mineralisation bands 5-10m thick.
Midwest A is about 450m long, 150-235m below surface, and 10-60m wide on average.
Denison’s flagship eastern Athabasca Basin uranium project is 95%-owned Wheeler River, which it describes as the largest undeveloped uranium project in the area.
“Since the completion of the Wheeler River pre-feasibility study in 2018, Denison has invested in the development of a highly skilled and motivated Saskatoon-based technical team that has demonstrated industry leadership in the evaluation of the application of the ISR mining method to high-grade uranium deposits in the Athabasca Basin,” Denison CEO David Cates said.
“We are encouraged by the results of the Midwest concept study, and we are pleased to continue the further evaluation of the potential application of the ISR mining method to Midwest, with the support of our partner Orano.”
Denison said ISR mining accounted for a significant portion of uranium mine production globally and was generally considered the lowest-cost uranium mining method in the world because it eliminated surface disturbances and costs associated with physically removing ore and waste from the ground.
It also removed a need for conventional tailings treatment and storage.
The method saw a lixiviant – a mining solution – injected into the ore zone through a series of drill holes, or injection wells. The lixiviant leached the uranium as it travelled through the ore zone and was then recovered as a uranium bearing solution which was pumped back to surface via a series of recovery wells.
The solution was sent to a surface processing plant for chemical separation of uranium.
After removal of the uranium, the lixiviant was reconditioned and returned to the wellfield for further use.
Denison has a current market value of about US$825 million.