Strata gets draft approval for low-pH uranium recovery recovery

Strata Energy has taken a significant step towards securing approval to change practices at its uranium mine in Crook County. The company hopes to switch to a low-pH lixiviant that would vastly improve recovery rates at the Lance Projects near Oshoto.

The Department of Environmental Quality (DEQ) announced last week that it has issued an initial draft decision to approve Strata’s license amendment application, which would allow the company to switch to a low-pH lixiviant in the in-situ recovery (ISR) process.

Strata submitted its request a year ago, explaining at the time that its permit to mine only authorizes the use of alkaline and oxidant solutions. The ore deposit, however, has proven only moderately amenable to these alkaline solutions since recovery efforts began in December 2015.

Because of this, the overall recovery rates proved to be below targeted levels. A series of bench-scale tests in late 2017 showed that significantly more uranium could be recovered using low concentrations of sulfuric acid.

In November, Strata was granted permission to perform a small-scale field trial using low-pH lixiviant as part of the DEQ’s consideration of the company’s amendment request.

“Strata is still in the middle of the Field Leach Trial (FLT), but so far the trial has been successful,” says Melissa Butcher, Communications Specialist on behalf of Strata.

“Strata has finished the operational phase of the FLT and is now moving into the restoration phase. The results of the FLT will be publicly available once we submit the Interim Operations Report to WDEQ at the conclusion of the trial.”

According to a press release from Strata, the demonstration area used for the trial consists of three adjoining recovery patterns that had previously been operated to “economic exhaustion” using the alkaline lixiviant, “but are now yielding substantially elevated solution uranium grades and correspondingly higher recovery rates”. Data so far suggests an increase in uranium head grades from less than ten mg per liter to around 50 mg per liter.

Strata believes the demonstration has shown not only that the low-pH lixiviant can be successfully used at the site, but that the results achieve the boost in recovery that the company seeks.

“We are very pleased with the results to date from our low pH field demonstration, with the mining phase of the demonstration meeting all key performance objectives and validating the Company’s extensive laboratory results which demonstrated that substantially increased amounts of uranium can be extracted efficiently from this ore body using low pH chemistry,” commented Wayne Heili, Managing Director/CEO of parent company Peninsula Energy, in the press release.

The next state of the process to amend Strata’s permit to mine is a public comment period, open until June 15. During this time, information and the application can be reviewed in the Land Quality Division offices of the DEQ in Sheridan and Cheyenne, or at the County Clerk’s Office in Sundance.

Written comments or objections must be sent to the Administrator of the Land Quality Division of the Department of Environmental Quality, 200 West 17th Street, Suite 10, Cheyenne, WY 82002 before close of business on June 15. Only the amendment is open for public review, not the permit to mine itself.

If, during the public comment period, an objection is received that specifically requests a public hearing and is found to have been made by an aggrieved party as defined by Wyoming statute, a public hearing will then be held.

“DEQ may still elect to make changes to the license based on public comment without a public hearing,” notes Butcher.

Once the comment period closes on June 15, says Butcher, and assuming a public hearing is not requested, the target is for final approval to take around 30 days, although it may take longer.

If final approval is granted, she continues, a detailed implementation plan has been spelled out in the amended permit to mine.

“Strata must accomplish the four stages of the implementation plan to be fully operational with low pH; this could take months or years, depending on meeting the criteria to move from one stage to the next. Stage 1 of the IP is essentially the Field Leach Trial,” she says.

“The implementation plan is also incorporated into the amended Source Materials License, a copy of which [has been] delivered to County Clerk’s office…and is available for public review.”