Mineralogical and geochemical characterization of Nyamuliro Wolfram Mine Tailings, Rubanda District, Southwestern Uganda

Abstract

Nyamuliro Wolfram Mine is located in Rubanda District, Southwestern Uganda in the Akanyaru Ankole Supergroup geological formation. The selective mining methods used in Nyamuliro has generated huge volumes of tailings since 1970s. The artisanal and small-scale mining activities. Mineralogical characterization using X-ray Diffraction show that Nyamuliro wolfram mine tailings have several mineral types of quartz, alite, huanzalit, piemontite, halloysite, sanmartinite, muscovite, lizardite and pyromangite. Petrological analysis shows presence quartz, wolframite, pyrite, chalcopyrite, arsenopyrite and some sphalerite, ilmenite and gold. The geochemical characteristics of the tailings show a high concentration of wolfram (5.39-46.94 wt%) iron (27.54 to 64.97wt%, titanium (2.96 to 9.45 wt% for mine tailings and 2.22 to 6.18 wt% for metallurgical tailings) yttirium concentrations (0.10 to 0.66 wt% for mine tailings and 0.06 to 0.28 wt% for metallurgical tailings). Also in detectable amounts are other critical elements such as Nb, Ta, Zn, Pb,As and Hg. The high quartz content of the tailings makes them suitable for the manufacture of ceramics, cement and other industrial applications. The results also show that Nyamuliro wolfram tailings are viable secondary resources for wolfram and other critical metals including iron and gold. The presence of sulphide minerals and high concentration of heavy metals requires that the tailings are properly managed to avoid exposure that can lead to environmental pollution through acid mine drainage and release of heavy metals. The shaking table and process fines are likely harboring most of the heavy metals and critical metals. Recovering wolfram and other critical metals and minerals from these tailings at a profit will in turn provide solution for difficulty engineering and risks of slope collapse. It will also provide a robust plan to manage the formation of acid mine drainage and minimize the contamination of water bodies and soil within the mining communities.