A Modified Oxygen Consumption Test to Evaluate Gas Flux through Oxygen Barrier Cover Systems

摘要

The evaluation of an oxygen barrier cover performance is an integral part of many reclamation programs that aim at limiting acid mine drainage (AMD) production from sulphide tailings. The oxygen flux through the cover to the underlying reactive tailings should then be much smaller (by a factor of 1000 or more) than the flux into exposed (uncovered) tailings. Different techniques have been developed over the years to assess this flux. Given the limitations encountered when using available approaches to measure such low oxygen flux, the authors have developed a modified testing and interpretation method based on the oxygen consumption (OC) test, which is commonly used to determine oxidation rates of uncovered tailings. The proposed modifications to the OC testing procedure are presented in this paper, together with the new interpretation method. Typical tests results obtained with the modified OC method on an existing site, reclaimed using a layered cover with capillary barrier effects (CCBE), are presented and discussed. The results demonstrate that the modified oxygen consumption (MOC) test is an effective tool to assess the performance of oxygen barrier covers used to prevent AMD.