Mapping mine tailings using airborne geophysical and hyperspectral remote sensing data

Mine tailings are the waste products from mining operations. Most mine tailings contain a considerable amount of reactive sulphides which can cause acid mine drainage (AMD) when exposed to air and water. AMD constitutes a threat both to the environment and to public health. Increased awareness of AMD has led to growing activities in mine-tailing monitoring and reclamation worldwide. Mining companies in Canada are required to provide information to provincial governments about their waste disposal and control activities. There is an urgent need to develop new automated ways to provide information on short- to long-term evolution of tailings, thus enabling the mining companies to monitor their tailings more effectively.; The overall goal of the thesis is to explore the potential of hyperspectral remote sensing and geophysical techniques for mapping variations within and immediately outside of the tailings. Data used for this study are from three sources: airborne geophysical data, hyperspectral casi and Probe-1 data, and field data.; This study has contributed to both the remote sensing data analysis techniques and the understanding of mine-tailing surface and subsurface processes. Specifically, this study has the following important findings: (1) Airborne magnetic and electromagnetic data can provide information regarding the subsurface distribution of mine tailings on the basis of sulphide mineral content. A procedure has been developed in this study to use these data sources for rapidly surveying large tailings areas. This procedure can minimize expenditures for mining companies when designing remedial plans for the closure of the mines. This study has also identified regions of enhanced conductivity that extend beyond the tailing containment area. This information indicates seepage pathways, and is important for monitoring the effectiveness of tailing containment structures. (2) High-spatial-resolution hyperspectral casi (Compact Airborne Spectrographic Imagery data, which cover the visible and near-infrared wavelength ranges, can be used to detect the occurrence of AMD and separate broad oxidation zones of the tailings. With broader spectral coverage, hyperspectral Probe-1 (an imaging spectrometer that covers the visible, near-infrared and shortwave infrared wavelength ranges) data can be used to reveal the mineral compositions of the tailings surface. (3) This study has revealed some of the limitations of the well-respected XRD (x-ray diffraction) analysis technique for detecting certain minerals. Alternatively, the image unmixing technique applied to high-resolution hyperspectral data can provide supplementary information about the mineral compositions of the samples. (4) This thesis provides guidelines, in the form of a table, as to how mining companies can use the techniques explored in this thesis to monitor mine tailings.