Emerging Technology for Economic and Ecological Sustainability in the Rehabilitation of Metal Mine Tailings

摘要

Successful rehabilitation of tailings landforms of tens to thousands of hectares in size at base metal mines is critical to milling companies' 'social licence to operate'. Rehabilitation technology used is closely related to both the economic sustainability of the mining company and the ecological sustainability of the mined environment. Conventional technology to rehabilitate mine waste landforms is costly and constrained by the availability of soil (to reconstruct root zones) and clay materials (to reconstruct compressed layer). Depending on mine waste properties and site-specific resource availability, it is .not uncommon to cost A$0.1-0.5 M/ha for the establishment of conventional cover systems over mine waste domains, which.often accounts for large proportion of the total closure costs. This can lead to costs approaching several hundred millions dollars for rehabilitating larger tailings and acidic waste rock using conventional cover systems. The present extended abstract proposes a suite of new technologies to tackle the problems outlined above and discusses critical factors in successful rehabilitation from substrate levels to the whole landform performance, in two key aspects:1. in situ engineering of tailings soil to offset/reduce materials required,2. in situ chemical engineering of massive hardpan layer through alkali-activation and mineral gel cross-linking network mechanisms to encapsulate reactive tailings and achieving sustainable hydro-geochemicai stability in root zones. This aims at functionally replacing the roles of the compressed clay layer and capillary breaks in conventional covers. These technologies would improve both the economic and ecological sustainability of mine waste rehabilitation, thus addressing the triple-bottom line of mining and mineral processing industries not only in Australia but other countries.