The evaluation of acid mine drainage by kinetic procedures and empirical models for field scale behaviour

Acid mine drainage is an important environmental hazard due to its serious chemical contamination to the surface and groundwater resources. To provide enough and representative data for developing restoration techniques, this time-dependent geochemical process should be investigated based on kinetic principles. Thus, the kinetic column test generally utilized in the earlier studies without any accepted procedures related to the column dimension and properties of materials such as particle size and mass of samples to be tested for this purpose. To overcome the dissimilarities between the mass release rate of contaminants specified in the laboratory and in the field, and to upscale laboratory-based measurements to the field, kinetic column tests were performed by using different columns filled with crushed coarse and fine ore samples. The fluctuations of pH values and the concentration of various constituents were determined during kinetic column tests. The effluents of columns turned to acid after a lag time of between 21 and 65 weeks depending on the column dimensions and particle size. Statistically significant predictive models for upscaling geochemical behaviour of AMD processes were presented based on simple and multiple regression analyses among column dimensions and main parameters controlling the rate of acid generation.