Methodological approach for mineralogical characterization of tailings from a Cu(Au,Ag) skarn type deposit using QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy)

Abstract

Skarn type deposits are important potential resources for Cu, Au, and Ag as well as other strategic metals, which require accurate characterization of the mineralogy, texture and grade for successful processing and environmental management. The mineralogy of these deposits and of the resulting tailings has traditionally been examined using transmitted light microscopy, cathodoluminescence, X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. In the present study, the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN (R)) technology was applied to rapidly acquire spatially resolved mineralogical data from tailings associated with a Cu(Au,Ag) skarn type deposit. The resulting modal and textural data provided relevant additional information on the distribution of the ore minerals, including detail on the trace minerals, grain size distributions, and mineral associations. The following benefits of detailed mineralogical knowledge from this study can be pointed out it improves the lithotyping of these complex deposit types and will benefit their ore processing strategies; it allows inferences to be made about the environmental behavior of the tailings, namely the acid mine drainage potential; it provides data about deportment of penalty and toxic elements, which are specifically As, Te, and Sb. Thus, particular applications of QEMSCAN include assessments of the acid consumption of the mineral assemblages (mainly assured due to calcite and dolomite) and of the abundance, distribution and mobility of potentially toxic elements, such as As.