Geoelectrical Signatures of Acid-Generating Mine Waste Rock
Abstract
Acid mine drainage (AMD) contamination associated with waste rock piles (WRPs) at mining sites is a global concern, and understanding the generation and release of AMD from these piles is highly desirable. Traditional WRP monitoring techniques involve the installation of monitoring wells and periodic core sampling; however, these approaches are invasive, expensive and can only provide data with limited spatial and temporal resolution. An attractive alternative is non-invasive geophysical techniques that can provide non-invasive and continuous information on subsurface features and processes. This thesis aims to investigate the feasibility of the spectral induced polarization (SIP) method for monitoring changes in mine waste rock characteristics. Waste rock samples were obtained from three WRPs in the Sydney Coalfield in Nova Scotia, Canada. The properties of the waste rock were extensively characterized before kinetic column leaching and humidity cell experiments were performed on the samples with simultaneous tracking by SIP. Results show that the waste rock contained very low sulfide concentrations with SIP unable to capture distinct mineralogy changes during oxidation of the sulfides. However, SIP was extremely effective in monitoring the changes in the waste rock porewater characteristics associated with metal leaching and AMD flushing. Overall, this thesis improves our understanding of the capability of SIP to track changes in waste rock, while also introducing a robust approach for future experiments on waste rock and SIP.