Chemical Leaching of Sulfidic Mining Waste, Plombières Tailings Pond, Eastern Belgium: Insights from a Mineralogical Approach

Abstract

Historic sulfidic mine waste material poses both an economic opportunity and an environmental threat (e.g., acid mine drainage). Due to low metal content in the mine waste and complex mineralogy, metal extraction of metal of interest is challenging. The Plombières tailings pond in eastern Belgium was selected as a case study to determine the potential for metal extraction of targeted metals from three different types of mine waste (metallurgical waste, brown, and yellow tailings). Material from this historic tailing originates from the exploitation and pyrometallurgical processing of the Mississippi Valley-type ores. The examined mine waste contains amounts of lead and zinc which can be potentially recovered by developing a hydrometallurgical method, which is selective for zinc and lead with respect to iron. From the three selected chemical extraction techniques, i.e., sulfuric acid, methanesulfonic acid, and sodium hydroxide solutions, the best results were given by sodium hydroxide solution leaching, due to negligible concentration of Fe in pregnant leaching solution, and leached metals were not precipitated into new mineral phases. Pb and Zn showed, however, a leaching efficiency of only 22% (0.0–63.6%) and 14% (0.0–29.1%) in average respectively. Furthermore, this study investigated how the mineralogy of mine waste material influences the leaching efficiency of the samples. Regardless of the lixiviant and the material, the highest leaching efficiency of Pb and Zn was achieved for samples where abundant Pb and Zn minerals were present. In samples where no Pb- or Zn-bearing minerals were detected, leaching efficiency was lower or negligible.