Valorization of acid mine drainage treatment sludge as remediation component to control acid generation from mine wastes, part 2: Field experimentation

• Sludge may be integrated in an AMD prevention and control strategy at Doyon mine site.
• Results from two seasons of field test cells monitoring are presented.
• Waste rock-sludge mixture over waste rock reduced AMD from the waste rock.
• Tailings-sludge mixture over tailings was efficient as oxygen barrier.

The possibility of using acid mine drainage (AMD) treatment sludge as a cover component to control AMD generation from mine wastes was investigated through laboratory characterization and kinetic column testing (companion paper). The results showed that mixtures of sludge and waste rock, and sludge and tailings, may be integrated in an AMD prevention and control strategy at Doyon mine site (northwestern Quebec, Canada). In order to further investigate these scenarios in realistic climatic conditions, instrumented field test cells were installed on site to evaluate the performance of the mixtures to control AMD generation from tailings and waste rock under natural field conditions. The main findings from two seasons of monitoring are presented in the paper. The waste rock-sludge mixture placed over waste rock was able to reduce the generation of AMD from the waste rock, therefore confirming lab results, and was able to produce a neutral effluent with low concentrations of dissolved metals. The tailings-sludge mixture placed over tailings, with an evaporation protection layer, maintained a high volumetric water content and reduced sulphide oxidation from the tailings as exhibited by a neutral effluent. Monitoring of the field cells will continue to provide valuable information on the possible sludge valorization options.