Generic decision-making on the retreatment of copper tailings dams

Tailings dam retreatment can be considered as a profitable alternative when tailings contain relatively high metal contents. Moreover, because of low exploration, mining, processing and closure costs, and the recent rise in copper prices, retreatment may generate positive cash flow. Meanwhile revenue from metal extraction can offset rehabilitation cost leading to an improved long-term liability performance. A systematic approach and an Excel spreadsheet model are developed to evaluate economic profits, environmental and social benefits derived from retreatment, and to simulate human decision-making processes. Fuzzy logic and fuzzy-neural equations were employed in the model to deal with imperious and linguistic inputs, and to simulate human’s decision-making process. By user questionnaire and surveys, the model receives inputs data, which will be processed through four different modules to generate final outputs. Economic and Design Module completes conceptual processing flowsheet design, cost estimate, and economic analysis of base case and retreatment project. A Disposal and Reclamation Module is designed to select re-processed tailings disposal and reclamation methods, estimate cost and evaluate the environmental performance. A Risk Assessment Module is aimed at environmental and social risks evaluation of current tailings site. After receiving all the criteria on economic, environmental and social performance improvement, a Decision-Making Module is developed to provide user a recommendation. Generally speaking, this model is able to conceptually design activities from mining to reclamation; evaluate economic, environmental and social benefits; assist multi-criteria decision-making. Four hypothetical cases with different conditions have been processed to validate and verify the retreatment model. As indicated by model running results, the tailing retreatment module is an effective tool to assist in decision making. In addition, the system is working properly and efficiently on given inputs over a range and combination of values.Applied Science, Faculty ofMining Engineering, Keevil Institute ofGraduat