Column test investigation on the performance of monolayer covers made of desulphurized tailings to prevent acid mine drainage

Doyon mine (Quebec) explores the possibility of reprocessing concentrator tailings by environmental desulphurization, and using the desulphurized tailings as cover material for the existent tailings ponds to prevent acid mine drainage (AMD) generation. A laboratory study using instrumented columns was undertaken to evaluate the effectiveness of monolayer covers made of desulphurized tailings. The desulphurized tailings were placed in columns to evaluate the influence of residual sulphur content of the cover material, water table level, and thickness of the cover layer on water quality after repeated leaching. Configurations involving covers made of desulphurized tailings and water table located in the acid-generating tailings were able to control the production of AMD and to reduce the release of zinc and copper in the leachates by more than 87% and 98%, respectively. The covers also reduced the oxygen flux available under steady state conditions for reactive tailings oxidation by up to 96%.