Results of Vegetation Survey as a Part of Neutralizing Lime Sludge Valorization Assessment

The use of the lime neutralization process is a common technique to treat acid mine drainage (AMD) generated by sulphidic mine wastes. The AMD-contaminated water collected on the mine site is neutralized by addition of air, lime and flocculant. The sludge generated by the treatment is stored in specifically designed storage ponds. A multidisciplinary project is being conducted to investigate if sludge may be valorized as a material for mine site reclamation. The Doyon-Westwood mine site, operated by IAMGOLD, has two sludge ponds which were colonized by vegetation shortly after sludge deposition. One objective of the study was to investigate metal bioaccumulation risk by plants, to evaluate the sludge's suitability as vegetation growth medium. Ten functional groups of plants were found on the sludge ponds. Arborescent species were among the most frequent vascular plants on the sludge ponds. Chemical analyses of tissues from three arborescent species (leaves, branches, wood and roots) have indicated that the trees growing on the sludge were not affected by the deficit of major nutrients. The metal concentrations in the plant tissues sampled on the sludge ponds fit in the range of those from a al analyses of plant tissues did not reveal any bioaccumulation. The sludge shows a significant potential as a vegetation growth medium.