REACTIVE TRANSPORT MODELLING OF THE GENERATION OF ACID MINE DRAINAGE: ENCOURAGING RESULTS AND LIMITING FACTORS

The model MIN3P is a general-purpose reactive transport model that simulates the interactions of mass transport and geochemical reactions in variably-saturated media. MIN3P has been applied to mine tailings environments in previous studies, and has proven successful in small-scale simulations. MIN3P has been used to model a portion of the INCO Copper Cliff tailings impoundment to demonstrate the application of the code to a larger scale setting. Over a decade of field work at the site has allowed calibration of the conceptual model. This conceptual model includes variably-saturated flow conditions, diffusive gas transport, mineral dissolution and precipitation (including equilibrium reactions and kinetically limited reactions), and redox reactions (including reaction kinetics). The complexities of the physical and chemical characteristics of the impoundment, and the absence of fundamental thermodynamic and rate expression data for some of the phases present, limit the implementation of the conceptual model. The agreement between observed and simulated flow, geochemical, and mineralogical results, however, indicates that MIN3P is able to describe most conditions observed in the field.