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Dr Kathryn Moore

Small-scale mining

Since demand is increasing for a wide array of technology metals, there is a critical need to examine how mining solutions can be diversified and extended with minimal negative impacts. The current mining paradigm is centred around large-scale operations uting the economies of scale. But there are existing and feasible technologies for selective mining of small ore-deposits by small-scale operations. There is a difference between mining of small deposits and small-scale mining operations. Small deposits are necessarily described using geological and metallurgical terms, in order to engineer mining and processing solutions. The practice of mining small deposits transects historical and contemporary narratives: Many of the opportunities for future mining lie in former mining districts that were never exhausted of mineral deposits, but that suffered the impacts of mining that was not environmentally or socially regulated. Scale describes the size and complexity of mining operations and their social and environmental impacts, both positive and negative. Small-scale mining operations may be used on small ore deposits and also on large ore deposits for project staging reasons. The re-direction of small deposit mining is described by Moore et al (2020).

Small-scale mining will have smaller and shorter duration economic and environmental impacts than large-scale mining of low-grade ores. Opportunities exist to consider mining of small deposits as part of locally-diversified economies, remediated environments, and geographically-dispersed and secure raw materials supply. Small-scale mining is not supported by current trade, reporting and finance models. But increasing global demands for best practice, equitable distribution of opportunities and reduction of carbon emissions are external forces that may create a climate amenable to the expansion of mining of small deposits.

IMP@CT is an acronym for ‘Integrated mobile modularised plant and containerised tools for selective, low-impact mining of small, high-grade deposits’. The project was funded by the European Union’s Horizon 2020 research and innovation programme under grant No 730411 (2016-2020). The IMP@CT project partners investigated the potential to expand European capacity to access its regional resources, following from four key traits of the whole system:

  1. Risk of raw material supply disruption can be reduced by accelerating the response of mining to market demand, facilitated by access to multiple small deposits in Europe.
  2. A new mining paradigm is needed that does not rely on extensive investment and the economies of scale.
  3. Energy demand and mine waste should be reduced by limiting the volume of rock removed from the ground and crushed.
  4. Mining solutions should have a minimal footprint to support multiple land uses for high population density, and an ethical relationship with community.

The project partners developed technological readiness for non-artisanal, sustainable small-scale mining that would be suitable for extraction of metals from small ore deposits in Europe, based on understanding of minerals processing circuits (e.g. Segura-Salazar and Brito-Parada, 2021). A new selective underground mining tool was designed and developed with small size to reduce the size of underground workings and leave rock in place. The cutting head was designed to control the size of particles at the rock face, reducing the need for subsequent crushing of rock (Celtic Miner 4500 Midi). Waste material was further separated from metal-rich rock, prior to crushing by ore sorting technology (Rados). A portable processing plant was designed and developed to adapt to different ore deposits. All of the technological infrastructure was designed to be mobilised in 20-foot long containerised modules, so that it could be transported to ore deposits located in rugged terrains and rapidly deployed in a configuration that has a small environmental footprint. The component parts were integrated and tested on two mine sites in the west Balkans in 2019. The first deployment was at the Olovo lead mine in Bosnia and Herzegovina, where all processing occurred on site. The second deployment was at the Velicki Majdan processing site in Serbia, to process antimony ore from the nearby Zayaca mine.

The partners established boundaries within which to discuss what constitutes a ‘small deposit’, prioritizing the notion of ‘high-grade’. The researchers aimed to understand how small a deposit can be and remain viable to mine, and to gain some appreciation of the extent of opportunity for mining of small deposits in Europe. They adapted an existing search engine (EU-MKDP) that enables any end-users to identify and locate small, high-grade complex deposits. Europe is a region with a varied geological history, such that there are many and diverse small, high-grade ore deposits.

The partners interrogated the societal solutions that would facilitate the mining approaches (Sidorenko et al, 2020) and worked on prediction of environmental impacts (Knobloch and Lottermoser, 2020). Energy consumption reduction by selective mining, crushing and processing meant that the IMP@CT system could be powered as consistently and more cost-effectively in Europe by renewable energy provision, than by fossil fuels alone (Paneri et al, 2021). This is a significant development since the mining industry accounts for approximately 10% of world energy consumption. The environmental loads of mining are not limited to carbon emissions. The processing methods, the treatment of industrial water and the opportunity to use IMP@CT solutions to process and thereby remediate legacy wastes were all investigated. Life Cyclye analysis was perfomred from both environmental (Beylot et al, 2021) and societal (Mueller et al, 2021) perspectives.

The IMP@CT project showed that technical solutions are available now to accelerate decoupling of mining from negative environmental impacts and human well-being, in contribution to ambitious 2050 targets. The solutions will bridge the gap until more future-facing innovations are developed in the coming decades. However, the IMP@CT project also showed that small-scale mining solutions cannot succeed without reshaping of existing customary patterns of the governance of socio-economic impacts of mining. There are four key issues that must be addressed for the future development of small-scale mining on small, high-grade ore deposits in Europe:

  1. A positive relationship between mine and community must be prioritized, even in short-duration operations, underpinned by local micropolitical and cultural understanding.
  2. Permitting and licencing processes must continue to protect environment and society, while enabling mine operators to react swiftly to market opportunities.
  3. The role of short-duration mining must be placed within a diversified local or regional economic base, to protect the community from the withdrawal of the mining industry.
  4. Further innovation in handling of waste is required, since short duration mining operations must not create a long-term environmental legacy.
Some of the outputs of the IMP@CT project: