Tailings and Mine Waste Conference

Application of high-resolution microscopy methods to the analysis of fine-grained and amorphous treatment sludges Martin, Alan J.; Fawcett, Skya; Kulczycki, Ezra; Loomer, Diana; Al, Tom; Rollo, Andrew


Lime addition is a common method for the treatment of acid mine drainage (AMD) whereby neutralization promotes a reduction in acidity and the precipitation of metals as voluminous sludges that may contain gypsum, calcite and a spectrum of other phases. Due to the extremely fine-grained and often amorphous (i.e., non crystalline) character of sludge solids, the composition of these materials has been difficult to elucidate. Traditional methods, such as X-Ray Diffraction (XRD) and optical microscopy, have proved largely ineffective. In order to provide further insight into the solid-phase characterization of neutralization sludges, samples from mine sites across Canada were examined by high resolution microscopy techniques, including Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and X-ray Absorption Spectroscopy (XAS). The results revealed sludge-specific host phases, including relatively pure Feoxyhydroxide, amorphous Mg-Al-(Fe) hydroxysulphate and amorphous metal hydroxides. The data indicate that the nature of metal phase associations is strongly dependent on AMD influent composition.[All papers were considered for technical and language appropriateness by the organizing committee.]

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