Forward-thinking on mine tailings
AREVA Resources Canada using synchrotron to study traces of molybdenum
"Our partnership with the U of S and Canadian Light Source to better understand our tailings at McClean Lake helps us provide assurance that the environment is protected over the very long term," states Dale Huffman, AREVA Resources’ Vice President Safety, Health, Environment and Quality.
The company, a leader in clean nuclear energy, uses synchrotron techniques to investigate the life cycles of elements of concern, such as lead, arsenic, and molybdenum, at miniscule concentrations impossible to observe with conventional techniques.
Uranium ore mine tailings, or milling waste, at McClean Lake is stored in a repurposed open pit mine, where layers of tailings represent the evolution of uranium mill tailings over time. Drilling down into these layers gave the U of S-AREVA team an opportunity to directly observe tailings at different stages in their lifetimes.
"We want to know how the materials that contain these elements of concern are changing over time, and if they reach a point where they form an insoluble product in which case everything would stay put," says Dr. Andrew Grosvenor, the U of S lead on the project.
By shining the Canadian Light Source’s bright light on 25 differently-aged tailings samples, the team could see even slight fluctuations in molybdenum-containing materials over time. While a thermodynamic model predicted that the formation of solid molybdenum materials would eventually stop the element from dissolving into water, this was the first study to test and confirm this model.
The result will be invaluable to the long-term care of the site, and researchers are prepared to move on to other elements of concern.
"Once you understand the geochemical reactions that are occurring then you can start to predict what will be occurring over the next 50, 100, or 1,000 years in the environment," says Grosvenor.
This post first appeared as a press release for the Canadian Light Source.
Blanchard, Peter ER, John R. Hayes, Andrew P. Grosvenor, John Rowson, Kebbi Hughes, and Caitlin Brown. "Investigating the geochemical model for molybdenum mineralization in the JEB Tailings Management Facility at McClean Lake, Saskatchewan: A X-ray absorption spectroscopy."Environmental science & technology (2015). DOI: 10.1021/acs.est.5b00528