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From the synchrotron to the mine, and back again: A chemist’s tale

Date: 
Friday, December 14, 2018 - 14:00 to 15:00
Speaker: 
Dr. Andrew Grosvenor
Affiliation: 
University of Saskatchewan
Event Category: 
External Examiner Seminar
Location: 
Chemistry D200

Abstract:

One focus of the solid-state chemistry group at the University of Saskatchewan is to increase our understanding of materials by use of synchrotron radiation-based techniques. During the first part of this talk, I will discuss our on-going collaboration with Orano Canada to study how the tailings (solid waste) from the uranium mill located at McClean Lake, Saskatchewan change over time. Uranium ore bodies contain many mineral phases beside uranium oxide that need to be disposed of in a responsible fashion. Solid mining waste can be placed in a tailings management facility (TMF), which is designed to contain the waste elements and limit interaction with the external environment. To understand how a tailings facility will behave throughout the lifetime of the mining operations that feed the tailings management facility, and after the site has been decommissioned, it is important to understand the chemistry of the tailings and how they change with time.  This part of the talk will focus on our use of X-ray absorption spectroscopy and X-ray microprobe to identify the Mo- and Ca-bearing minerals in the TMF, and to determine how the concentration of these solid phases change over time.  During the final portion of the talk, I will discuss the recent studies that we have conducted on the corrosion of polymer-coated rebar in collaboration with multiple potash mining companies located in the Province of Saskatchewan. Corrosion prevention of concrete embedded steel reinforcing bar (rebar) presents a major concern because of concrete spalling. Concrete spalling occurs when concrete cracks and falls away as a result of the internal pressure applied by the increased volume of corroded rebar. The effect of concrete spalling is often exacerbated by the high chloride environments sometimes found in mining and industrial sites. Polymer coated rebar is one of the corrosion mitigation strategies that can be used to limit concrete corrosion Several techniques exist for the study of corrosion for polymer coated steel; however, they require the removal of the polymer film to effectively study the steel surface.  We have recently developed a method for collecting X-ray microprobe maps of the corrosion of steel at the polymer-steel interface without removal of the polymer coating, which will be discussed.