By Angelina Costain
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Geological Sciences PhD student Brett Moldovan. Photo by De-Tong Jiang |
If you look close enough, you just might be able to make out the path worn into the highway that leads from Saskatoon to Rabbit Lake. This is the path made by Brett Moldovan, PhD student in Geological Sciences at the U of S, who traveled the road countless times over the past six years while he completed his studies and worked full-time for Cameco.
If the truth were told, however, Moldovan has been wearing these paths much longer than the last six years. After receiving a BSc Chemistry in 1989 from the U of R, Moldovan worked in the mining industry for ten years, making tracks to both the Rabbit Lake and Key Lake uranium mines, before applying for graduate studies at the U of S to research arsenic in mine tailings.
Arsenic is an unwanted toxic impurity in base metal, uranium and gold bearing ores. The milling of these ores to extract the metal of interest results in the dissolution of arsenic from the host rock. This process often increases the toxicity and bioavailability of the arsenic. Bioavailability is the probability of a substance acting negatively upon the human body. The arsenic must therefore be processed in the mill before being transferred to the mine tailings management facility, both to make it less toxic, and to ensure that it does not leach from the tailings into the regional groundwater.
Using the Rabbit Lake uranium mine as his study site, Moldovan’s thesis involved the development of a scientific process to assess stability of contaminants of concern in mine wastes. Specifically, he wanted to determine the most effective way of stabilizing arsenic during the production of mine tailings and to assess the bioavailability and long-term stability of arsenic in these mine wastes.
The first stage of Moldovan’s research involved using synchrotron science to understand the chemical nature of arsenic in mine tailings. Then, creating a large mill-scale experiment at the Rabbit Lake mine for the second stage, Moldovan chemically treated several hundred thousand liters of arsenic-bearing process water to determine the best way to treat arsenic before putting into the tailings. The final stage involved conducting experiments and developing a three dimensional diffusive transport model to determine how arsenic migrates through tailings (and potentially reaches groundwater).
Moldovan’s research concluded that the arsenic within the mine tailings was properly treated in the mill, meeting regulatory requirements, and showing long-term stability with no impact on regional groundwater.
The interest in Moldovan’s research has been enormous, particularly in his use of synchrotron science. “It is a fundamental tool,” he says, “for understanding contaminants in all types of geological materials.” Before the synchrotron there had been no way of determining the chemical nature or stability of arsenic. However, his scientific process has since been used by several mining industrial companies to study not just arsenic, but other contaminants in the environment, as well.
Moldovan’s post-doctoral plans involve as much travel as ever. He says that he would like to continue teaching, conduct more synchrotron research, as well as continue working at Key Lake mine where he is now superintendent. He would also like to continue collaborative research with the U of S to investigate different areas of interest to the uranium mining industry.
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Angelina Costain is a student writer with the College of Graduate Studies and Research
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