Field investigation of controlling acid mine drainage using alkaline paper mill waste

To verify in situ laboratory test results for the control of acid mine drainage using alkaline paper mill waste, five demonstration cells were built on the Ascot mine site in Sherbrooke (Quebec, Canada). A monitoring program was set up to record temperature, leached water quality, oxygen concentration and electrical conductivity. Monitoring results showed that mixing mine residues with alkaline paper mill waste and covering mine residues with paper mill waste allows an efficient control of acid mine drainage. The paper mill waste cover generates an alkaline front which results in metal precipitation as hydroxides. Also, an increase in pH results in an inhibition of bacterial catalytic activity. Chemical analyses conducted on the collecting water shows a high reduction of leaching metals to under ground water. Moreover, a significant reduction of diffusion of oxygen to the mine residue is observed.