Modelling leachate generation and mobility from copper sulphide tailings – An integrated approach to impact assessment

The long-term management of the large volumes of solid wastes produced during mining and minerals processing represents a significant challenge to these resource-based industries. While ensuring geotechnical stability is imperative, it is the continued generation and mobility of contaminated leachate that is potentially the most serious and pervasive environmental issue faced. Yet, wastes from these industries remain poorly characterised and the mechanisms of leachate generation and the eventual fate of contaminants poorly understood. An integrated approach to solid waste impact assessment has been developed and is partly demonstrated here for porphyry-type copper sulphide tailings. Particular attention is given to leachate generation modelling informed by detailed waste characterisation, which together with fate and transport modelling forms the basis of the approach. The strength of this methodology is that it begins to quantify the complex interrelations between the process generating the waste, the waste deposit and its management, and the resulting environmental impact.