eNews November 2018

NMT Hydrology Student Studying Leaching at Old Uranium Mine Sites

by Thomas Guengerich, NM Tech Office of Communication and Marketing

SOCORRO, N.M. – New Mexico Tech doctoral student Alexandra Pearce is using an NM WRRI grant this year to study the potential for revamped uranium mining in northwest New Mexico.

The New Mexico Water Resources Research Institute, located at New Mexico State University, funded Pearce with a $6,000 grant. She is gathering and examining samples collected from deposits in the Grants Uranium District, which stretches from east of Laguna to west of Gallup. The district, though dormant since 2002, remains seventh in the world in uranium production. It supplied over a third of the United States’ uranium over 50 years, generating $4.7 billion in revenue.

“This grant has been an immense help because it should tide me over to cover all the analyses I have to do,” she said. “The NM WRRI funding covers a big part of the electron microprobe, leaching tests, and sundry other tests. This grant was a God-send. I am really grateful because I was wondering how I was going to fund this project.”

Pearce had previously received competitive scholarships and grants from N.M. EPSCoR, the N.M.  Geological Society, and SRK Consulting.

Pearce is combining in-depth mineralogical and geochemical characterizations with results from batch leaching tests to better understand the fundamental controls on metal leaching.

“There’s a lot of uranium remaining in New Mexico and it’s a multimillion dollar industry,” Pearce said. “In situ recovery is the best option for mining because there are no pits or tailings. If you have a good understanding of the hydrology, you can keep it pretty controlled. In situ recovery is the predominant method of uranium mining and it could be great for the state of New Mexico.”

Pearce has collected some samples from the Saint Anthony mine in Laguna, which is in the process of remediation. The majority of her samples are from cores drilled in the 1970s and 1980s, held by the N.M. Bureau of Geology’s core archives in Socorro.

She is characterizing her samples using thin-section petrography, electron microprobe analysis, infrared spectroscopy, and bulk geochemistry analyses.

So far, her work has shown that samples higher in organic matter release far less of their total uranium than those lower in organic matter. The next step in her research is to determine how to increase uranium yield from these high organic matter deposits.

A native of South Africa, Pearce earned two bachelor’s degrees from Penn State University in geobiology and geosciences with a hydrogeology option. She earned her master’s degree from St. Louis University in geoscience. She expects to graduate in May 2020.