This article is a combination of two papers that will be presented at Life-of-Mine 2016, which was held in Brisbane from 28-30 September 2016.
The mining industry should embrace the circular economy to improve its sustainability and create value.
The concept of the circular economy has been gaining traction both in Europe and China.
In Europe, the Ellen MacArthur Foundation sees its mission as accelerating the transition from a linear take-make-dispose economic model to a circular model that is restorative and regenerative by design and aims to keep products, components and materials at their highest utility and value at all times. Furthermore, the European Commission has adopted a Circular Economy Package, including revised legislative proposals on waste, to stimulate Europe’s transition towards a circular economy to boost global competitiveness, foster sustainable economic growth and generate new jobs. China’s Circular Economy initiative is effectively a sustainable consumption and production program utilising cleaner production, industrial ecology and life cycle management approaches to meet the national challenges of maintaining rapid economic growth while simultaneously enhancing environmental quality and maintaining social progress. A key characteristic of both of these circular economy initiatives is to design out, re-use or minimise the generation of waste.
By definition, the mining sector is represented by linear rather than circular activities through its supply of resources to society. However, being one of the world’s largest waste generators, the sector can adopt similar logic to that of the circular economy to improve its sustainability performance. Waste is a critical issue along the whole metals value chain, from mining waste to eventual end-of-life products such as scrap steel from construction and demolition waste or the growing problem of electronic waste. While the mining industry has only made a limited contribution to the circular economy so far, the current market conditions, which are prompting calls for greater innovation, make the timing right for the industry to boost its contribution by utilising and generating value from mining waste or making it available as a feedstock from which other industries can harness value.
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Mining in the circular economy
Each waste stream along the metal value chain has its own set of environmental issues. For example, the concerns around tailings dams differ from those related to electronic waste. The opportunity to create value and reduce environmental liability from waste streams along the value chain is potentially one way that the mining and metals industry could make substantial contributions to the circular economy and, in doing so, improve sustainable development.
The circular economy (along with other related sustainability concepts) provides a system perspective of waste elimination through the rethinking and redesign of products and processes along the value chain and between supplier networks. One approach to accelerate the uptake of the circular economy is by introducing new innovative business models that deeply embed its principles into the way that companies generate and capture economic value (Table 1). Circular business models are disruptive, innovative business models aiming to drive the sustainability of the whole business network (system) through circularity (Forum for the Future, 2016).
In many cases, the most challenging (and massive) waste stream within the metals supply chain is upstream (ie mining waste). Due to significantly lower grades for most extracted minerals and metals, tailings can account for up to 99 per cent of crushed and ground ores (Edraki et al, 2014). In addition, there is also a ‘hidden’ unaccounted flow of waste rock and overburden (Mudd, 2010).
Different strategies for managing mining waste can be characterised in terms of their ability to decrease the risks and consequences of environmental legacy and in generating economic value out of waste. An example of such characterisation is presented in Figure 1, which is based on multiple sources of information including, but not limited to, Edraki et al (2014), Franks et al (2011) and McLellan et al (2009).
An integrated, multidisciplinary approach to mining and metal waste is needed. Without such an approach, it will not be possible to account for the different social, economic and environmental dimensions of sustainability, engage with the network of actors within the metal supply chain and look beyond short-term economic benefits and risk-averse behaviour to target the supply of restorative and regenerative resources in a circular economy model.
Applying the circular economy to the sustainable mining challenge
The key tenets of the circular economy are utilising resources efficiently, limiting final waste disposal and reducing losses of valuable material. There are various opportunities to implement circular flows at the mine site level, which would result in enhancing mineral extraction, reducing mineral losses to mining waste and mitigating some of the environmental impacts related to mine waste disposal. In particular, acid and metalliferous drainage (AMD) occurs as a result of sulfide minerals remaining in mining waste because of inefficiencies in the extractive process. Recovering these minerals or stockpiling mineralised waste material in a way that enables future recovery while controlling leakage may contribute to an improvement in the site’s environmental health and result in economic gain. Making the most of the waste material and the minerals within it contributes to enhancing the overall resource extraction at a mine site. As a result, this would reduce the need for new mines to some degree.
Research work at the Sustainable Minerals Institute at The University of Queensland has produced a framework that allows a mine site’s performance to be assessed with regards to the circular flow of minerals. This framework has two sections:
- the first establishes a set of material flow indicators (MFIs) – such as Mineral Losses to New Waste, Total Mineral Losses to Waste, Extraction Inefficiency and Circularity – that are relevant to a mine project during operation
- the second examines the mine’s entire life cycle on a more qualitative basis.
Distinguishing these two dimensions is relevant as there can be more than one mining project over a mine’s entire life. A vast majority of mining projects close or cease operations before the mineral resource is exhausted, often without any planning for future use of the remaining mineralised material (Laurence, 2011). Observing the mine’s entire life cycle allows for a better understanding of the consequences on mineral losses due to operating interruptions. This qualitative and holistic perspective also provides the opportunity to investigate alternatives in business models.
The history of the Mount Morgan mine site in Central Queensland is characterised by three distinct mining projects. While the initial operations focused on mining the orebody, the two latest projects are dedicated to mine waste reprocessing. Results from the aforementioned framework indicated that the previous project for reprocessing mining waste did not make a significant positive contribution to the site’s environmental state. However, the current proposed project is much more promising, highlighting significant differences in the extractive strategies of the two projects. By taking a life cycle perspective, it is possible to show that poor waste management, premature closure and inefficient extractive strategies can amplify mineral losses (either temporarily or permanently) through resource sterilisation and AMD.
The developed MFIs are a first step in quantifying the performance of a mining project regarding the sustainable management of its natural resource. The lack of long-term consideration for the whole life of the mine and the uncertainty of mining projects due to market conditions can significantly contribute to irreversible mineral losses. The identification of practices and strategies that anticipate the future use of material beyond the life of a mining project and/or contribute to making mining projects economically viable in the longer term (and consequently avoid interruptions) will assist in preventing these issues.
Future pathways to the circular economy
Further investigation and research to heighten the industry’s participation in the circular economy is necessary in certain key areas. Technical solutions for re-use are a key area, and there has already been significant work in this area. For instance, bauxite residue (or red mud) utilisation has been actively investigated for more than a decade (Paramguru, Rath and Misra, 2004). Research is still required on new and emerging technologies. Other critical areas that need addressing include:
- the potential reduction in environmental liability and legacy issues from mining waste re-use
- the resulting feasible community benefits due to lower environmental risks
- the opportunity for local enterprise development from mining waste utilisation
- smarter reverse logistics to provide cost-effective transportation of the higher economic value chain options (see Figure 1)
- more innovative business models to help create value from mining waste coupled with updated regulation that promotes greater resource utilisation.
To make a transformational change to managing mining waste, all of these factors need proper analysis to determine the most feasible pathways that both consider economic, technical, environmental and social factors and contribute to the circular economy.
The authors would like to thank Carbine Resources, in particular Russell Dann and Patrick Walta, for their generous contribution to the Mount Morgan case study. The authors would also like to acknowledge the support of the Wealth from Waste Research Cluster, a collaborative program between CSIRO, the University of Technology, Sydney, The University of Queensland, Swinburne University of Technology, Monash University and the Center for Industrial Ecology at Yale University.
Edraki M, Baumgartl T, Manlapig E, Bradshaw D, Franks D M and Moran C J, 2014. Designing mine tailings for better environmental, social and economic outcomes: a review of alternative approaches, Journal of Cleaner Production, 84:411-420.
Forum for the Future, 2016. Circular economy business model toolkit [online]. Available from: www.forumforthefuture.org/project/circular-economy-business-model-toolkit/overview
Franks D M, Boger D V, Côte C M and Mulligan D R, 2011. Sustainable development principles for the disposal of mining and mineral processing wastes, Resources Policy, 36:114-122.
Laurence D, 2011, Establishing a sustainable mining operation: an overview, Journal of Cleaner Production, 19:278-284.
McLellan B C, Corder G D, Giurco D and Green S, 2009. Incorporating sustainable development in the design of mineral processing operations – review and analysis of current approaches, Journal of Cleaner Production, 17:1414-1425.
Mudd G M, 2010. The environmental sustainability of mining in Australia: key mega-trends and looming constraints, Resources Policy, 35:98-115.
Paramguru R K, Rath P C and Misra V N, 2004. Trends in red mud utilization – a review, Mineral Processing and Extractive Metallurgy Review, 26:1-29.