Use of solid residues from civil construction as a covering system for acid mine drainage abatement in an abandoned pyrite mine

In Ouro Preto/MG, pyrite was exploited at an old mine from 1930 through 1967. Considered as one of the best resources of pyrite in Brazil, this mine was exploited in order to supply sulfuric acid for explosives manufacturing, at the President Vargas Plant in Piquete/SP. The mine site is abandoned and has slope instability and acid leakage generation as the main environmental liabilities. Lately, the site has been used for illegal deposition of all sorts of urban waste. The Ouro Preto Administration, on its turn, has the intention of using part of the mine site for the disposal of solid residues of civil construction. This paper presents the results of kinetic tests carried out, in leaching columns, to assess the acid mine drainage potential in samples collected from the mine site and to evaluate the possibility of controlling and minimizing acid generation by using solid residues as a covering system. Laboratory results show that cover with solid residues of civil construction was effective in the reducing the acidity, concentration of metals and sulfate.