Mine waste or future resource? Integrating industrial ecology thinking into a mining project

Abstract

Growing demand for natural resources coupled with declines in ore grades globally areincreasing the environmental footprint of the extractive industry, in particular throughhigher energy and water consumption and waste generation. There are a variety ofsustainability frameworks that have been designed for the mining industry and each ofthese define principles and strategies to improve the industry’s sustainability performance.However, most of these frameworks are missing a key characteristic related to thefundamentally different nature of mining compared with other industrial activities: themineral resource itself. An important contribution to sustainable development by miningprojects is the way they manage to maximise value and minimise waste from ore deposits,each deposit having its own unique properties.Industrial ecology (IE) is a multidisciplinary field of research that studies the flows andstocks of material and energy within society, and their impact on the environment, with theaim of designing more sustainable production and consumption systems. This thesisapplies industrial ecology ideas and tools to the metal mining industry, and focuses onflows of mineralised material, observing the causes and consequences of mineral lossesoccurring at the mine site level.The IE framework developed has three main levels of analysis. The first level focuses onmine waste management. Mine waste management practices were reviewed andassessed in terms of whether they inhibit or enable future mineral resource recovery, orany other value creation from the local mineralised material. A new Mine WasteManagement Hierarchy ‘reduce – reprocess – downcycle – dispose’ was developed inaccordance with principles of waste minimisation and value maximisation, and illustratedwith examples from reported practices as well as academic research.In order to connect better the mine waste management system with the rest of the mine’smetabolism, the second level of the framework proposes a set of Material Flow Accounting(MFA) indicators, which provides a general view of the site’s internal mineral flows. Thisset places a particular emphasis on quantifying mineral losses, which occur throughdifferent dissipative mechanisms, and with an evaluation on whether these losses areirreversible or potentially recoverable. The MFA indicators have been applied on two case studies in Australia: the former goldand now abandoned mine, Mount Morgan in Queensland, and the copper mine, MountLyell in Tasmania. As both mine sites have had long histories, they have hosted severalmining ventures whose performances have been assessed and compared using the MFAindicators. Comparisons of the different mining ventures at each case study site allowedfor identifying the conditions for prolonging the life of mining operations and increasingmineral recovery, either from the ore deposit itself or by recycling mining waste. Suchoutcomes are desirable from a sustainability perspective in the sense that they take intoaccount both the exhaustibility of a non-renewable resource and the need to minimiseenvironmental impacts of mineral-rich waste material. The MFA results also allow forquantifying the consequences of unplanned and incomplete closures, long-terminterruptions in operations and poor waste management, which have all contributed toexacerbating mineral losses.The third and last level focuses on the role of governments in relation to the two casestudy sites. In particular, it was found that governments have a significant role to play, andthis was demonstrated through the strengthening of environmental regulations over thepast century, which has led to reduced mineral losses. However, the Queensland andTasmanian governments’ regulatory frameworks still could be improved in order to preventor better control the consequences of premature closures of mining projects. This wouldrequire stronger links between the relevant environmental protection and mining stategovernment departments. Using the Mine Waste Management Hierarchy as baseprinciples for best practices in mine waste management, and using the MFA indicators toassess the performance of mining projects during the approval process could both informpolicy-makers on potential ways to improve the current regulatory systems and helpstimulate a positive change in mining practices.