By Sarah Pridgeon
A white paper is now available detailing the research behind Strata Energy’s proposal to change the leaching medium used to extract uranium at the Ross ISR Uranium Mine near Oshoto. The company is in the very early stages of seeking permission to revise its permit, says CEO Ralph Knode, but hopes the change will vastly increase the mine’s production rate.
The proposal, says Knode, is to change the medium used to leach uranium from the Ross deposit, known as lixiviant. Until now, an alkaline solution has been employed just as at most other Wyoming uranium sites, but research this year has increased Strata’s understanding of the deposit and made it clear there are key differences to other sites in the state, Knode explains.
Strata is currently permitted through the State of Wyoming and Nuclear Regulatory Commission to use alkaline and oxidant based medium, but this has not proved as fruitful as the company once hoped. Instead, Strata proposes to revise the permit to allow the use of low pH medium, which preliminary tests suggest may increase the recovery rate substantially.
“The research showed that we’re unlikely to achieve the results that we anticipated and that would be required for sustainable, long-term development. We said, ok, what do we do? We’ve got to look at how to change this,” Knode says.
“We are mining uranium every day, just not to the levels that we anticipated and that would make it commercially viable.”
The substance used would likely be sulfuric or citric acid with a pH equal to the acidity of lemon juice, Knode says, and the concentration would be around 1.4 percent in the groundwater.
Low pH mediums have been used in Wyoming before, though they are not currently in use, and there are no regulatory prohibitions on its use in the state. It is also used worldwide to recover a variety of minerals, says Knode, such as copper in Arizona and uranium in places such as Australia and China.
In fact, 96 percent of the 77 million pounds of uranium mined through in-situ leaching methods worldwide in 2015 came from facilities using low pH medium , Knode says.
The Ross ISR hit hard times not long after it began production, with uranium prices reaching a 12-year low in the second half of 2016 as the market became flooded with product. Last December, Strata’s parent company, Peninsula, announced that the Ross mine’s stage two expansion would be placed on hold until market conditions improved.
At present, Strata holds supply contracts at prices above the spot market. These in-place contracts are helping to bridge the gap while uranium prices remain low and position Strata to be able to respond when those prices rebound.
“That’s the only reason really that we’re able to keep our doors open right now,” Knode says.
The project was developed to be scalable, he explains, which gives Strata flexibility to capitalize on the still-recovering global uranium market and allows expansion in response to market conditions while reducing up-front capital costs.
“We’ve permitted the entire operation, all the way from the well fields through to drying and packaging the yellowcake, but we’ve not built the whole thing. We’ve only built what I call the front end of the plant, which is the ion exchange portion,” he says.
“That scalable development has really helped us a lot to get up and going.”
The advantages of switching to low pH mining include the potential to recover a higher percentage of uranium, a potential reduction in water consumption and shorter mining duration. It is also thought to allow a higher degree of natural attenuation during restoration, allowing the water to revert to its original state naturally.
“We think that the groundwater restoration can be accomplished more effectively after a low pH leach than after an alkaline leach in the same formation. That’s something we would obviously have to prove, but that’s what we’ve seen in the laboratory,” says Knode.
Changing to a low pH solution would not change Strata’s target to restore the groundwater to a standard equal to or better than it was before, according to statutory requirements, once the mine reaches the end of its life, Knode says.
“We’re not proposing to change that – we think we can do it as well or better than we’re already committed to,” he says, pointing out also that the company has been mining for two years and has not seen mining materials migrate outside the area of the wells.
The company will also continue its extensive groundwater monitoring network and program, testing wells twice per month and domestic wells within two kilometers quarterly, though the parameters of that testing may change slightly to ensure they are appropriate.
The Ross ISR Uranium Mine was and is an opportunity for the U.S. to expand its domestic production of energy and reduce its reliance on foreign sources, says Knode. Nuclear energy currently provides one fifth of the electricity in the United States.
The white paper now available on Strata’s website at stratawyo.com is intended to condense the information available so far into a single document and give specific evaluations of the environmental and human health aspects of using a low pH medium. Knode says the company wants to keep stakeholders informed and engaged and hopes the white paper will contribute to this goal.
“There’s a process here, and it’s a long process, and we’ve really just taken the first step. It’s been our company’s policy before I even walked through the door five years ago to be very open and transparent and responsive,” Knode says.
The process of amending the permit is expected to take between 18 and 24 months.