Integrated Modular Plant and Containerised Tools for Selective, Low-impact Mining of Small High-grade Deposits

Periodic Reporting for period 3 - IMPaCT (Integrated Modular Plant and Containerised Tools for Selective, Low-impact Mining of Small High-grade Deposits)

Période du rapport: 2019-06-01 au 2020-11-30

The current resource production paradigm supports large-scale and low-grade mining of world-class ore deposits. Global financing models are not suited to the extraction of the specialist metals required in small quantities for technological innovation, because it will not generate a large enough return. A diversity of mining solutions is required that continue to scale up extraction for bulk metals, find new mechanisms for by-product recovery, or facilitate extraction of technology metals from small-scale and high-grade ore deposits. However, in all cases, mining must operate to minimise negative environmental, social and economic impacts, to reduce waste, energy and water consumption.

The IMP@CT project proposes a solution that develops a new switch on-switch off (SOSO) mining paradigm to improve the viability of small complex ore deposits. Our whole systems approach centres around technological innovations in mining equipment design and mine planning that would reduce the feasibility studies required, throughput of extracted material, infrastructure, land use, resource consumption and waste. Successful business models for SOSO mining require that mining and processing technologies can be adapted to multiple deposits and commodities. Risks that are associated with the approach concern geological uncertainty, metallurgical variability and social acceptance. Our overall objectives were to demonstrate that the concept of SOSO mining is viable using case studies in the West Balkans, and to understand the wider settings in which it can work in Europe.

The entire mining system produced lead concentrate in Bosnia and Herzegovina, at the Olovo mine site and then antimony concentrate from an ore deposit in Serbia, in a way that is conductive to low carbon production, environmental management and low impact on society.

The potential for production from small, high-grade ore deposits in Europe can be viewed using a dedicated data layer in the existing EU Minerals Knowledge Data Platform (EU-MKDP) (http://minerals4eu.brgm-rec.fr/minerals4EU/). Rapid screening of the “Small scale complex deposits” is of use to exploration and mining companies, and other stakeholder groups. Enhanced data acquisition at the outset of exploration is supported by an initial petrographic reporting strategy that includes semi-quantitative mineral liberation data. The early identification of challenges for processing and subsequently valorisation of a deposit allows the operator to focus on the most prospective deposits. A small-spaced geostatistical sampling approach was used to further describe variability ore veins as a means to determine business risk.

Mining and processing units were design to fit and/or operate in 20 foot long containers. The cutting head of the selective mining tool controlled particle size, thereby reducing the need for primary crushing. Operational challenges arising from reduced run-of-mire after selective mining were examined using a one-container comminution circuit, deployed to site in half a day. An XRF ore sorter of reduced dimensions for a one-container module created sufficient high-grade stockpile of ore for the gravity beneficiation plant to operate in semi-continuous mode. The mobile processing test facility comprises four twenty-foot containers connected by walkways and modified for attachment of jigs and spirals, with flexible piping and electrical configuration for adaptability to different mine sites and run-of-mine feed. It was deployed in just three days, such that the system has proven ability to respond to market demands, where there is adequate licensing in place.

Tests at the Olovo lead mine site (Bosnia and Herzegovina) constituted in-situ processing activity. The second test site was the processing site at Veliki Majdan, treating ore from Zajača antimony mine in a satellite mining and processing model. Samples and data were generated to test simulations of ‘switch on’ or ‘switch off’ (SOSO) mining and processing, where limited knowledge existed of variable ore deposits. Objects were tracked through the different stages of the process using a combination of advanced scanning and liberation analysis. Process flowsheets arising from desk studies and metallurgical testwork supported operations at test sites, were used to consider alternative antimony deposits and legacy wastes, and underpinned review of the suitability of chemical reagents for adaptable process solutions.

Environmental life cycle analysis showed that electricity generation was the key environmental hotspot, though other environmental impacts also required consideration. For SOSO mining, modelling showed that renewable energy or mixed renewable-energy diesel solutions were amenable to off-grid operations and more cost-effective than diesel-only energy provision. Water quality was predicted using a rapid infra-red technique and a treatment plant for industrial water was designed for increased modularity and portability. A research framework for evaluating the social impacts of switch on – switch off mining and social life cycle analysis were used to investigate perceptions of SOSO mining and measures that can be put in place by the mining operator. Community expectations for generations of employment in mining operations were largely informed by positive perceptions of past industrial operations in historic mining districts. The concept of small-scale mining was defined for a European context in terms of societal impact, as distinct from small deposit mining. Recommendations and training were devised to protect workers within a mature health and safety culture for SOSO mining.

Unless commercially sensitive, the results of the project are published, in preparation for publication/review, and/or disseminated at conferences and stakeholder workshops, including to industrial stakeholders. Policy-level dissemination included a meeting with ministers in Sarajevo ahead of on-site test work and circulation of a policy brief to the UK government ahead of the G7 summit and COP26. Dissemination to the public has culminated in an art collaboration and book publication: ‘Of Earth – For Earth. The meaning of a mine’.

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 order to realise ambitious 2050 CO2 emissions targets. We demonstrated 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:

1. A positive relationship between mine and community requires local micropolitical and cultural understanding.
2. Permitting and licencing processes need to both protect environment and society and enable mine operators to react swiftly to market opportunities.
3. The withdrawal of short-duration mining in a diversified local or regional economic base requires management.
4. Further innovation in handling of waste is required, since short duration mining operations must not create a long-term environmental legacy.

First deployment of the IMP@CT minerals processing facility at Olovo mine, Bosnia and Herzegovina

Periodic Reporting for period 3 - IMPaCT (Integrated Modular Plant and Containerised Tools for Selective, Low-impact Mining of Small High-grade Deposits)

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