Column leaching test to evaluate the beneficial use of alkaline industrial wastes to mitigate acid mine drainage

This paper presents laboratory investigation to evaluate the capacity of basic residues to inhibit acid mine drainage. Coluirin tests have been set up with unoxidized tailings, oxidized tailings, waste rock, cement kiln dust, and red mud bauxite. Columns were also performed by leaching oxidized tailings mixed with 10 and 50% alkaline materials. Finally, column tests have been carried out to simulate layered comingling, covers, liners, and co-disposal of waste rock and fine tailings. The pH results obtained show that the addition of alkaline materials permits to keep near neutral conditions in the fine material layer. No significant difference in pH values was obtained with mixture of 10 and 50% alkaline material. When the fine-grained layer overlays reactive waste rock, a delay was observed before achievement of near neutral pH. In the cases where the fine-grained layer are below or mixed with the waste rocks, the near neutral pH values are directly reached.