Blue Mining Strategically Integrates Circular Economy

The mining industry faces a complex and pressing challenge driven by an increasing demand for raw materials and a socially demanding and globalized world. The extraction of primary raw materials has gained importance as one of the cornerstones of humanity’s sustainable development, significantly because the necessary raw materials to evolve towards a sustainable future as copper, lithium, nickel and cobalt could be sourced by 2050 only in 10 % by recycling. Therefore, the remaining needed 90 % must be sourced by primary extraction (1). Furthermore, raw material extraction is faced nowadays with higher environmental and safety standards and regulations. In addition to the industry’s efforts toward responsible mining, these challenges offer the opportunity to enhance “blue mining” as a sustainable holistic approach that integrates the principles needed to plan sustainable, reliable and responsible mines for today’s and future generations incorporating circular economy as one of its principles.

1  Motivation

Various factors, including environmental impact, resource scarcity, social responsibility, and economic uncertainty, shape the contemporary landscape of the mining industry. The production of minerals necessary to meet the demand from clean energy technologies is estimated to increase by 500 % in 2050 for critical minerals such as graphite, lithium and cobalt (2, 31). Easily accessible, high-grade ore deposits tend to be depleted, forcing mining companies to develop into deeper and more complex deposits. This has mostly affected the evolution of resources into reserves, influenced as well by a shift on investors value systems towards more sustainable practices, fluctuations in commodity prices and geopolitical uncertainties. Alternatives to develop novel approaches to solve this issue are currently under development such as Modular Mining Systems for scalable and adaptable mining projects (3). This concept is based on modular architecture for designing modern mines and centers on a future full electric, zero-entry, low-emissions, scalable and adaptable mine. Many mining companies have taken important steps to become more sustainable, implementing measures like progressive closure strategies, rehabilitation programs and developed renewable energy projects. This is enhanced by a stricter regulatory framework and ESG policies. In the European Union (EU), regulations such as the Critical Raw Materials Act and the Net Zero Industry Act promote mining. These see mining as important for the energy transition and promote more sustainable ways of working in the industry (4, 5). Embedded in social memory however are particularly negative environmental impacts, such as landscape sprawl, depletion of local water resources, water pollution and emission of greenhouse gases. Despite the efforts, the public image has not yet changed. In order to change this perception, the industry must do a better job of communicating their sustainable practices and the steps they are taking towards a more responsible and sustainable future, advocating for transparency and fostering trust.

Disruptive technologies and new developments such as digitalization, automation and electrification drive the digital transformation (DT) in mining. Nonetheless, their implementation can result in an increase in capital expenditure which limits their propagation to the overall industry. Strategies to democratize the DT such as retrofitting for autonomous operation of machinery and agnostic systems for mine digitalization are currently under development. Furthermore, implementing new technologies can be a daunting task for any company. This is where change management (CM) comes when implementing disruptive technologies. It involves preparing an organization for changes, identifying potential resistance to change and effective communication. It helps to ensure that the implementation is successful and the benefits of the new technology are maximized. Without CM, the implementation of new technologies can be chaotic and problematic, causing more harm than good. Moreover, the DT requires mining engineers, electrical, mechatronics, software and affine required disciplines with a deeper understanding of information systems. Skills that could be supplied by a younger workforce born in this digital era. Unfortunately, the industry faces the enormous challenge of attracting a younger generation that is not interested in raw materials extraction. The need for action is hereby intensified by an aging active workforce on the way to retirement and the forecast of a rising demand for critical minerals.

In this challenging environment, the further development of the concept of blue mining offers a promising solution. This requires a fundamental shift from the traditional linear economy approach to a sustainable, circular economy strategy. For the mining industry, this means the introduction of innovative technologies, the increased recovery of materials from waste and the consistent questioning and application of circular principles along the entire life cycle of a mine. This transition will not only help reduce environmental impacts, but also improve the economic stability and social acceptance of the mining industry.

2  Blue mining in the context of the circular economy

Blue mining is a concept developed by the Institute of Mining of Clausthal University of Technology (CUT), Clausthal-Zellerfeld/Germany, presented at the 6th International Conference on Sustainable Development in the Minerals Industry, in 2013 to reshape sustainability practices in mining. The term “blue mining” was inspired by the definition of the blue footprint and comes, from the German, “Blaupause” which stands for responsible mining in which sustainability is incorporated from the very first planning phase.

In general, blue mining describes mines that are sustainable, energy-efficient and ergonomic as an operation that

• operates in an energy-efficient and ergonomic manner;
• pursues full automation; and
• support sustainability by promoting the continuous use of mine sites during and after extraction.

Integrating these principles into the early stages of mining existence requires a fundamental redesign of mine planning towards an integrative mine planning approach. The idea of multi-use mines is also consistent with the central goal of the circular economy to use energy but also further resources and products repetitive times throughout their life cycle. Converting mines into multifunctional facilities during and after the production phase helps to promote resource efficiency and thus supports the core objective of circularity. Furthermore, this term includes the subsequent use beyond extraction, namely, in the case of optimization of energy use, as a possible energy supplier. Hereby, the operation could return the energy used during the extraction phase even after the extractive life spam of the mine has been reached. The integration of this concept must therefore be considered for mine planning over the entire life of a mine or deposit (6 to 15). This concept is supported by three stages. In the first stage, different opportunities considering the aspects of blue mining are identified and evaluated according to the project inherent situation. Then, synergies and conflicts of the interaction of the selected opportunity are identified. Finally, in the third stage, the detailed plan for integration is developed and assessed maximizing synergies and minimizing the conflicts that might occur (6  to 16).

The Department of Underground Mining Methods and Machinery at CUT has been involved in several research projects since more than ten years ago, integrating the concept as an alternative for planning post-mining strategies. Since 2011, different approaches have been researched regarding using abandoned mines in Germany (7 to 15, 32). These include the Energy and Water Storage Harz (EWAZ) and Water Storage Harz 2050 (WSH2050) projects. In EWAZ, alternatives for the after-use of underground and surface mines have been evaluated for water-stress regions, including an integrative approach using the forecast of flooding and drought periods in the affected region. The WSH2050 project focused on water quality development using a hydro-analytical water management tool to identify potential uses of mining infrastructure to support water management in the Upper Harz Mountains (17). Integrating mine infrastructure for energy and water storage and using alternative energy sources in the blue mining approach illustrates how resource efficiency can be promoted in mining, which is a central concern of the circular economy.

The concept of the circular economy revolves around a sustainable model of production and consumption. It promotes the sharing, leasing, repairing, refurbishing and recycling of existing materials and products, with the aim of extending the life cycle of these items as much as possible. By doing so, the amount of waste generated is significantly reduced creating further value (19). CUT has involved in this endeavor by adopting circular economy as guiding principle for research, teaching and technology transfer developing a holistic circular economy framework (Figure 1).

While mining is not the first industry that comes to mind when thinking about the circular economy, it is not entirely foreign to the concept. Moreover, as discussed in the Responsible Mining Leadership Forum 2023 held in England by the International Council on Mining and Metals (ICMM), the processes that currently take part in mining have not been built to support a circular economy. In fact, mining can play a role in it by extracting, reusing and re-purposing valuable raw materials from waste and discarded products. According to the framework of circular economy, redesigning products and processes stand for a key component when pursuing circularity. Considering the challenges, the mining industry is facing, disruptive technologies, developments and concepts, are changing completely the current way we plan, conduct and develop mining. To achieve this, new concepts are integrated into strategic mine planning having clear goals and objectives from the “blue print” of a mine leading to a maximization of resources beyond the mere life of the extractive mine (Figure 2).

Therefore, the advanced blue mining concept has implemented two changes: one is the addition of two more sustainability principles, water and circularity, to the previous energy and ergonomics aspects. Additionally, the early implementation of all aspects was complemented by integrative mine planning. The last is based on optimizing processes to minimize the resources that enter the mine and reduce the resulting outputs for every element part of mine planning. This way, advanced blue mining integrates and enhances circularity and sustainability setting a framework for the operation of sustainable mines that can increase and improve the image of mining as a sustainable and responsible extractive industry.

3  New aspects of blue mining

Experiences gathered in the integration of blue mining in research projects at CUT proved the relevance of integrative mine planning for the implementation of the concept. Planning is a vital aspect of mining operations and it involves a range of procedures and processes that must be adequately integrated to ensure a project’s success. From exploration and resource assessment to production scheduling, every stage of the mining process must be planned and executed with precision and accuracy. By integrating all the aspects involved in blue mining into integrative mine planning, mining companies can achieve better outcomes in terms of safety, efficiency, profitability and sustainability. By introducing water management optimization in early stages i.e., the most profitable areas for water use and optimization can be identified (see Chapter 3.2). Similarly, integrating circularity and circular economy principles since early stages can help mining companies optimize production and minimize the impact on the environment.

3.1  Integrative mine planning and circularity

Integrative mine planning entails all planning stages of traditional mine planning. It integrates circular economy and blue mining based on the principle of reducing inputs and minimizing outputs throughout the complete mining value chain. Integrative planning stands for the optimization of the use of resources and processes as a crucial step in achieving better sustainable results and improving overall efficiency. Integrative mine planning provides a clear view of the different resources required in the mining operation and provides a controlled overview on the generated outputs (Figure 3).

Considering the impacts of all elements and processes, planners can identify opportunities and forms to optimize their usage in mining. Therefore, figure 3 delineates the interconnections reached with circularity. In the following, selected circularity opportunities are introduced, however the mined material resulting of the extraction, as a product, has not been included here since its recovery is to be maximized. Considering waste rock as an example, discarded material can be used in the construction of facilities or as road construction material within and outside the mine site. Whenever is possible, alliances can be established to nearby quarries for processing and screening, to reduce costs for development drifts and to establish a new source of sustainable construction materials (20). For energy as an input, different sources of energy interact within one mining operation and can be composed by a mix of fossil fuels, compressed air and electricity. Depending on the type of operation, one type of energy source will have a higher demand than the others. Traditional and ongoing operations can have a higher demand on fossil fuels meanwhile modern operations, on the other hand, will have a higher demand of electricity. Either way, scope 1 and 2 emissions are generated. To better manage the generated emissions, different strategies can be implemented for reduction ranging from technological changes towards electrification and automation, to optimization of processes based on ventilation on demand (VoD) to reduce energy consumption since VoD can result in possible annual energy savings of up to 50 % (21). In the case of scope 2 emissions, some mining operations as Olympic Dam mine of BHP in Australia, have opted to source electricity from renewable sources going off-grid. This has resulted in lower costs, independence from the electrical network, elimination of blackout risk for remote operations and drastic emission reductions. Off-grid mines powered by renewable sources can drive down energy costs by up to 25 % in existing operations and 50 % in the case of new mines (22).

Moreover, in the field of energy generation, special attention must be set on blue mining, integrative planning, circularity and post-mining. The evolution of off-grid operations can have a positive impact not only during the mining operation but also after extraction has ceased. Hereby, after-use of mining facilities and infrastructure can be planned since early stages to support regional development for the post-mining era. Research at CUT has identified that one of the limiting factors when re-purposing abandoned or closed mines is the high capital cost required to rehabilitate and adapt the available infrastructure for the after-use. Integrative mine planning of post-mining strategies can create secondary profitable opportunities for mining operations since the necessary additional infrastructure can be developed along the mine life using fewer resources and reducing costs for the closure phase. The alternatives evaluated in the EWAZ project are a clear example of the opportunities of integrative mine planning and the potential of blue mining for regional development providing a circular alternative for regional energy management. Currently, the interconnection of mining facilities and renewable energy generation has been researched in Germany, Austria, Australia, Sweden, Netherlands, the USA, South Africa and Italy (23, 24, 25, 26).

Furthermore, an innovative alternative for scope 1 emissions reduction is the economic capture of diesel particles and carbon capture from methane in underground, surface and abandoned mines. The last is often associated to coal mining but can also be found in salt, potash, trona, diamond, gold, base metals and lead mines worldwide during mine operation and remain present as a latent risk in post-mining stages. In the case of ventilation air methane (VAM), two emerging technologies that enable carbon capture are regenerative thermal oxidation (RTO) and catalytic thermal oxidation (CTO). Another significant development is an initiative from Rockburst Technologies, an Australian start up, with their patent-pending Transcritical CO₂ Pulverization (tCO₂) technology where carbon dioxide is used for rock breaking in comminution reaching estimated energy saving levels of up to 55 % when compared to traditional methods (27). Moreover, the early integration of carbon capture and emission reduction policies in relation to carbon credits stand therefore as a profitable opportunity for methane extraction in mining operations (28). In the case of general consumables and spare parts management, circular initiatives have started by only introducing products in the mining environment that can be reused, refurbished, transformed or recycled to reduce the carbon footprint of the mine.

For a better overview on the possibilities of circularity in mining, table 1 includes the elements part of integrative mine planning and showcases them as inputs, outputs and proposes linked circularity opportunities.

3.2  Integrated Water Management in the framework of Blue Mining

The change in climate influences the global water cycle, so that by the year 2070, a total of 44 million Europeans will be affected by water scarcity. It is expected that the increasing water demand from various industries, including mining, will lead to more conflicts over water usage. To obtain a “social license to operate” and ensure long-term profitability, the mining industry must prioritize sustainable and circular water management (29). The concept of “Integrated Water Management” (IWM) has therefore evolved in the mining industry and other water-intensive sectors in recent decades to emphasize the need for comprehensive, sustainable and efficient use of water resources. This concept of sustainable and circular water management is also at the core of the Blue Mining Initiative.

IWM in mining represents a comprehensive approach to sustainably and responsibly utilize water resources throughout the entire life cycle of mining. This involves careful planning, accurate assessment, sustainable preservation, professional treatment and continuous monitoring of water usage. The primary goal of this approach is to minimize the impacts of mining operations on local water resources, protect water quality and ensure sustainable water management practices to reduce the operation’s water footprint without compromising production. Core elements of integrated water management include:

• Optimized use and reuse of water resources.
• Treatment and purification of waste water to remove contami­nants and ensure its return to the system and ecosystem.
• Avoidance of interference with natural watercourses and the preservation of biodiversity.
• Continuous monitoring of water sources and reserves to detect negative impacts early and enable optimal proactive planning.
• Employee and stakeholder awareness and education about the importance of water protection and management.
• Transparent involvement of the local community in decision-making processes to consider the needs and rights of all parties.

For the development of appropriate management strategies in mining, a profound understanding of both the climatic and hydro-geological conditions and water use in the five main life cycle phases of mining operations is essential. The required amount of water varies depending on the type of mine, applied technologies and processes, environmental regulations and regional water availability. Therefore, the five central phases – exploration, planning, production, closure, and post-mining (Figure 4) – are qualitatively examined in terms of varying water demand and changes in water quality.

3.2.1  Exploration

During the exploration phase, water demand is low, but there is a crucial initial evaluation of the water requirements for the project. A careful assessment of the hydrogeological conditions and the watersheds near the mineral deposit is carried out to identify early risks to local water resources. This process involves collecting and analyzing information about existing bodies of water, their watersheds and flow paths, as well as meteorological, geological and environmental data. The goal of these studies is to understand the hydrological system before mining activities commence and gather enough information to predict the qualitative and quantitative impacts of mining on local water resources. Additionally, other water users and stakeholders in the vicinity must be identified to proactively address and avoid usage conflicts.

Special precautions should already be taken during the exploration phase to minimize potential negative impacts on local water resources. This means that drilling campaigns must be carefully planned since misdirected drilling can have long-term effects on the water cycle and potential contamination. Therefore, the use of environmentally friendly drilling techniques and the careful handling of chemicals and resulting contaminated waters in accordance with local guidelines and laws are of paramount importance to minimize environmental risks.

In the initial phase, the overarching objective of the water management strategy is defined, which can vary depending on climatic conditions. In arid regions, the focus is on optimizing water supply, while in humid areas, facilities to prevent uncontrolled runoff, landslides or dam failures during periods of heavy rain flow are of particular importance. During exploration, the potential for water use during and after the operational phase should be identified. The specific usage strategy depends on the (hydro)geological environmental conditions, such as water availability, mineral composition, rock strength and geothermal gradients. Where possible, exploration drill holes should be strategically located so that, ideally, they continue to serve a purpose after exploration, such as being used as groundwater monitoring points in the mine’s monitoring plan.

3.2.2  Planning and construction

In the phase during which the detailed design of both the operational areas and the water is created, planning must also consider the future uses of this infrastructure after mine closure. It is essential to identify potential re-usage options early on. This allows for proactive technical planning, proper sizing and ensuring the stability of the infrastructure from the outset. These considerations should be integrated into a comprehensive mining plan that also includes details about underground mine service water systems, mining cooling systems, as well as plans for managing water inflows and civil construction with mechanical, electrical and instrumentation design.

With the start of construction at the mining site, the water infrastructure is simultaneously built, bringing the first visible environmental impacts, including changes in topography, surface runoff and hydraulic alterations in the aquifers. The water management and monitoring program evolve into a detailed description of the water system, providing more precise information about estimated water flows from various plant units and the mining area. At this stage, the critical factors of mining operations that have the highest water demand or the most significant impact on water quality are identified. It is important to examine whether process loops can be optimized and whether certain operational areas can function with lower water quality to reduce freshwater usage.

3.2.3  Production

During the operational phase of a mine, continuous data collection on water quality and quantity is of paramount importance. This data serves to update water balance models and management plans. Moreover, strict monitoring and reporting to the relevant authorities, as well as feedback to stakeholders in the watershed, are conducted. To sustainably utilize water during the operational phase, it is divided into three categories: process and gray water, natural water sources and waste water. Each of these categories requires specialized monitoring systems and, if necessary, treatment measures. Likewise, in this phase, various usage options for water are significant to minimize water demand while reducing the ecological footprint. Besides its use in ore processing, as cooling water, or for dust control, with appropriately designed infrastructure, water can be utilized for energy generation and storage for renewable energy production in solar or wind park facilities. The integration of these into mining operations simultaneously contributes to the energy efficiency of a site. Throughout the entire operation, water demand and water quality development must be monitored and reviewed at regular intervals. Adjustments may be necessary to account for changes in water availability, such as seasonal fluctuations. Water management strategies that extend beyond raw material extraction and are implemented during the operational phase should also present potential utility in the post-mining phase to avoid costly and time-consuming modifications.

3.2.4  Closure and post-mining

The closure phase of a mine marks the transition from raw material extraction to the post-mining phase. Careful planning and control of water management during the transition to the post-mining phase are essential, as this period can span several decades, and it is imperative to ensure the quality of life for the local population and the ecological integrity of the environment. In this phase of IWM, the focus is on water treatment and management after mine closure, with the aim of gradually reducing water demand and ensuring long-term water quality with minimal cost and monitoring effort. Traditionally, the emphasis during the closure phase has been on restoring the original environmental conditions. This approach, while environmentally friendly, is often not feasible, especially when significant hydrological interventions, such as redirecting surface water systems, have been made. For the closure concept, it is essential to minimize not only environmental impacts but also consider socio-economic aspects that involve the needs of the surrounding communities and other end-users.

For IMW, this means not only careful monitoring and ensuring water quality but also integrating the identified water usage potentials and existing infrastructure into regional energy and water supply systems. Possible usage options may include:

• geothermal energy;
• hydroelectric power generation;
• energy storage;
• electrochemical energy conversion;
• recovery of valuable materials;
• drinking water;
• process water;
• irrigation;
• aquaculture/hydroponics (using water in hydroponic systems for plant cultivation or in aquaculture for fish farming).

A comprehensive risk assessment for each usage option is essential, including considering the temporal development of water quality and quantity. Even though usage strategies in the post-mining phase should be considered during the mine planning phase. It should be reviewed whether the existing infrastructure and the geology influenced by mining are suitable for the intended use. Especially since the rock engineering properties may have changed significantly as a result of mining activity.

Finally, IWM in mining ensures that water resources are responsibly and sustainably utilized throughout the entire life cycle of a mine, with a focus on protecting local water resources and minimizing the water footprint. Key to effective water management is a deep understanding of both environmental conditions and water usage in the different phases of mining operations. Particularly during the closure and post-mining phase, it is crucial not only to consider environmental compatibility but also to consider economic and social aspects, including the needs of the surrounding communities, and create synergies to minimize usage conflicts. Ultimately, a forward-looking, integrated water management strategy can ensure that mining sites continue to make a positive contribution to regional water supply and energy generation even after their closure.

4  Conclusions and outlook

The blue mining concept represents a promising approach to lead the mining industry into a more sustainable and efficient future. The emphasis on responsible mining practices reflects the fundamental principle of the circular economy to develop sustainable business models that are more competitive for the contemporary shift the mining industry is facing. Both concepts complement and recognize the need to minimize environmental and social impacts while advancing economic development. Nevertheless, several challenges stand in the way of the successful implementation of the blue mining concept. A key challenge is the uniqueness of each mining site, which makes generalized application of the concept difficult. Each mining site has specific circumstances that need to be considered, such as different laws and regulations in different regions, which requires tailoring. In addition, accurate redesign of material cycles is critical, but requires transparent insight into current data that is not always readily available. Production and consumption data must be available in sufficient quality and digitally to perform a sound analysis. If such data is available, it can be used in comprehensive life-cycle assessments to identify optimization opportunities for each input and output of a mine. Finally, moving from linear to dynamic planning approaches requires close collaboration with government agencies and consideration of environmental constraints. This is necessary to ensure that the mining industry receives the necessary approvals and support to successfully implement the new approaches. If this transformation succeeds, the industry’s tarnished image can be improved in the long term.