Biogeochemistry, Bioextraction and Biorecovery of Rare Earth Elements

Lead Research Organisation: NERC British Geological Survey
Department Name: Minerals & Waste

Abstract

The rare earth elements (REEs) are a group of 17 metals (La-Lu, Y, Sc) that have been discovered to have a number of useful chemical and physical properties and have been harnessed by a range of industries. REEs have critical uses in production of electronic components used in every-day items (computers, smartphones etc), ceramics, alloys, magnets, LCD screens and even in contrast agents used in medical imaging, such as during MRI scans. Whilst REEs are found in ores all over the world, current methods for extraction and separation of REEs from ores only work efficiently with ores containing large amounts of REEs relative to the amount of rock present ("high-grade ores"), whereas the majority of REE ore deposits worldwide contain low amounts of REEs and high amounts of rock ("low-grade ores"). Without effective extraction methods for low-grade ores, the global REE supply chain is dependent upon the few countries that have high-grade ore deposits, such as China. This means that the UK and EU are importing enormous amounts of these metals from China each year, at great cost (REE prices increase daily) and with not just associated shipping costs but an environmental impact of that transit and a high "carbon footprint".
BioORE is a multi-disciplinary project lead by the University of Plymouth alongside the Universities of Manchester and Birmingham and the British Geological Survey, with the ultimate goal of exploring methods for extraction of REEs from low-grade ores found in the UK and EU, in order to try and provide us with a secure supply of these vital metals.
The University of Plymouth has developed a bioextraction procedure in which low-grade REE ores can be broken down by 'rock eating' bacteria in carefully controlled reactors, leaving behind a small amount of rock waste (that could be recycled) and a solution containing a mixture of REEs. This procedure is relatively inexpensive and does not use any harmful chemicals or product any pollutants -event the CO2 produced by the bacteria during the process is trapped for recycling and not released into the environment. A further biorecovery process has been co-developed by the Universities of Plymouth and Birmingham in which REEs can be recovered back out of the mixture produced in bioextraction in a selective manner - that is to say that the process separates out the metals from the solution. This is achieved using controlled reactors containing bacteria embedded in a type of plastic, over which the REE solution flows. The bacteria produce large amounts of phosphate during their metabolism, which reacts with REEs producing REE phosphate biominerals, which form crystals all over the cells in the plastic matrix. By using a range of different bacteria and different conditions, we can selectively biorecovery REEs from mixtures. The biominerals can either be used directly by industries that need them or can be further processed either chemically or biologically to meet industry's needs.
BioORE will bring together a range of international industries and will work with them to develop, optimise and scale-up these two biotechnologies with the goal of developing an effective method for REE extraction from low-grade ores. Use of a biotechnology is not only a means to fast and selective REE separation; it is also a 'green' technology, producing none of the harmful pollutants associated with current REE separation methods. These technologies will enable clean, 'green' REE production from low-grade ores found worldwide, permitting local production in countries that use them and reducing the CO2-burden associated to global transport.

Planned Impact

Rare earth element (REE) production is a multibillion dollar industry, with REE prices rising steeply, owing to major geopolitical issues regarding materials supply/security. REEs are major E-tech elements with vital roles in a range of technologies (below) but current extraction, refinery and separation processes are reliant on high-grade starting materials, limiting this to major ore deposits, which are not found globally. Recovery from low-grade starting materials (e.g. REE-bearing soils, low-grade ores) is inescapable on socioeconomic ground as demand for these valuable E-tech elements increases almost daily. BioORE strives to provide solutions to allow REE production from low-grade starting materials found globally through use of proven-in-principal biotechnologies, providing resource security and potentially stabilisation of market prices. Multiple nations across the globe have developed centres for REE research since 2005, striving to provide alternative extraction methods - it is critical that the UK and EU become stakeholders in research into security of supply of REE mineral resources and BioORE seeks to provide a potential route for EU REE production.
The latest global REE consumption data indicate they are used in alloy production (29%), electronics (18%), catalysis (18%), phosphors (12%), catalytic converters (9%), glass/ceramics (6%), magnets (5%) and other industries (3%), with over 400Gg in-use stock (Du & Graedel, 2011; US DOI/USGS 2010). The majority of REEs are currently produced in China (140Gg produced in 2007 alone and increasing annually) with virtually no production elsewhere. Though REE-bearing minerals can be found all over Europe, including the UK (monazites, xenotime, bastnaesite etc), they are often at low-grade and thus cannot be economically extracted using extant methodologies.
BioORE's main thrust is to develop means to resolve this issue of resource availability but lack of appropriate technology using coupled biological extraction and recovery methods. The geopolitical implications of an efficient extraction technology for low-grade resources coupled to a specific separation technology are immense and could open doors to REE production across the globe from local resources previously untapped. Leadership in this area will provide positive socioeconomic impact within the UK/EU during expansion in mineral supply. Increased mineral/resource security will develop from the ability to win REEs from a wider range of resources from a wider range of locations across the globe, breaking current geopolitical dominance. Additionally, with local supplies of REEs able to be tapped, mitigation of CO2-burdens associated with global REE transport will be possible.
Use of a biotechnology for REE production will negate the use of toxic solvents and associated pollution found in current technologies. A 'green' option for REE production will have impact on REE producing and consuming industries as well as on the environment and current and future inhabitants of Earth.
Immediate academic impacts will be new understanding of REE biogeochemistry, REE-microbe interactions, microbe-mineral interactions and REE biomineral production.
On the wider scale, BioORE will demonstrate the viability of 'green' mineral bioprocessing and will inform policy makers of the importance of exploring novel biotechnologies.

Publications

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Description The grant has allowed the development of a research consortia to build a strong cohort of scientists and industrial partners to submit a bid for the NERC Minerals Security of Supply research programme. The catalyst grant has identified microbiological avenues for accessing mineral resources that were previously uneconimically viable to extract.
Exploitation Route The research team that has been put together shows the multidisciplinary nature of science as we move forward. Other researchers will be able to use this grant as an example of how to weave together cohort of strong minded individual scientists into a team.
Sectors Chemicals,Electronics,Energy,Environment

 
Description The microbial avenues identified for accessing mineral supplies of critical elements have been used to build relationships with key industry partners.
First Year Of Impact 2012
Sector Other
Impact Types Economic