Thermal behaviour and performance of two field experimental insulation covers to control sulfide oxidation at Meadowbank mine, Nunavut

Abstract

Insulation covers are an appealing reclamation approach to control sulfide oxidation in tailings storage facilities located in the Arctic. In this study, the thermal behaviour and effectiveness of insulation covers for the reclamation of the Meadowbank mine’s tailings storage facility were assessed using both laboratory-based tests and field experimental cells. Oxygen consumption tests performed in controlled laboratory conditions indicated that a temperature of 0 °C is adequate to control Meadowbank’s tailings oxidation. Two instrumented experimental covers were constructed with 2 and 4 m of nonreactive waste rocks. Thermal monitoring of the experimental cells was conducted over 4.5 years and demonstrated a thermal regime dominated by heat conduction. The 2 m cover displayed temperatures at the tailings–cover interface greater than 0 °C for 94 to 124 days per year, whereas the tailings under the 4 m cover stayed below 0 °C year-round. Field oxygen consumption tests showed a reduction of 70%–90% in the oxygen uptakes measured for covered tailings compared to uncovered tailings. Calculations of yearly oxygen consumption fluxes showed oxygen fluxes less than 2 mol·m−2·year−1, confirming the effectiveness of the cover configurations to control sulfide oxidation.