Wyoming approves first use of low pH ISL uranium production

05 August 2019

Peninsula Energy Ltd has completed the regulatory process for the use of low pH in-situ uranium recovery at the Lance uranium projects in Wyoming, becoming the only operator authorised to use the technique in the USA.

Wellfields and header houses at Lance's Mine Unit 1 (Image: Peninsula Energy)

The Wyoming Department of Environmental Quality (WDEQ) formally approved an amendment to the Lance source materials licence on 31 July, notifying Peninsula Energy Ltd subisidiary Strata Energy Inc the following day. The authorisation confirms that low pH in-situ leach (ISL) methodology complies with the regulatory standards and requirements under the state regulator's purview.

Peninsula CEO Wayne Heli described low pH recovery - widely used elsewhere in the world - as a "proven and effective" method. The company began the process to amend Lance's licences in 2017, after tests showed that using an acidic rather than alkaline mining solution could potentially transform the project's operating performance and costs. "The final implementation of this initiative is anticipated to bring significant benefit for our shareholders," Heli said.

ISL, also known as solution mining, involves recovering minerals from a suitable orebody by dissolving them and pumping the pregnant solution to the surface where the minerals can be recovered. Consequently there is little surface disturbance and no tailings or waste rock generated. The orebody must be permeable to the liquids used, and located so that they do not contaminate groundwater away from the orebody. The choice of leaching solution - acidic or alkalinic - depends on the geology of the ore, but leaching using an acidic solution gives higher uranium recovery with lower operating costs than alkaline leach.

Peninsula wound down production from the Ross Permit Area at Lance during the second quarter of 2019 in preparation for the transition to low pH operations and alkaline operations are now idled, the company said on 31 July. It will now focus on an ongoing low pH field demonstration which is required under the amended Permit to Mine and must be completed before commercial operations can begin. The start of commercial scale low pH operations will be determined by "the timing and extent of improvement in the uranium market conditions and the companies' requirements for produced uranium," Peninsula said.

Ross was one of four US ISL uranium plants in production during the second quarter of 2019, according to US Energy Information Administration data published on 1 August. The other operations are Lost Creek, Nichols Ranch and Smith Ranch-Highland. All four are in Wyoming. The four operations produced a total of 44,569 pounds U3O8 (17.1 tU) during the quarter, down 24% from the first quarter of 2019 and down 88% from the second quarter of 2018.

Researched and written by World Nuclear News