Static tests response on 5 Canadian hard rock mine tailings with low net acid-generating potentials

It is crucial for mining operators to predict the acid-generating potential of their mine wastes as early as possible in a mine development project, because of the high remediation costs of acid-generating tailings and the risks of environmental issues associated with an incorrect classification of the wastes. However, many tailings having low net acid-generating potentials fall into the uncertainty zone of the static test. Different chemical and mineralogical static test results are compared in this paper for 5 Canadian hard rock mine tailings having low net acid-generating potential, in order to help determine which method is more appropriate for such tailings. Static test methods showed significant result variations (NNP or NP/AP) for each tailings tested, demonstrating the need to develop tools to identify the most appropriate technique for a given mine waste. Thus, static test selection guidelines were developed based on mineralogical considerations for each test. A modification to the Lawrence and Scheske method based on the Paktunc CNP method is proposed in order to improve its accuracy, which enables to account for the presence of oxidizable cations (such as iron and manganese) within the minerals.

► NP prediction procedures compared for low NP and AP tailings from hard rock mines.
► Ankerite and calcite are dissolved during modified Sobek II test.
► Siderite is partially dissolved in modified Sobek II test, while siderite is not.
► A modification to the Lawrence -Scheske method is proposed based on Paktunc CNP.
► A static test selection flowsheet is proposed based on tailings characteristics.