Is a sustainable UK lithium supply chain viable?

IOM3 Content Cafe
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26 Nov 2019

Lithium is considered essential for a low carbon economy. How can the UK ensure a sustainable supply?

Lithium is the ‘Irreplaceable Element of the Electric Era’, according to Volkswagen, and is therefore, uniquely, the metal that allows the world to move towards a low carbon future. As we progress rapidly towards electric vehicles and battery storage of renewable power significantly more lithium will be needed for use in lithium ion batteries (LIBs).

Europe is destined to become the second largest consumer of lithium after China as it races to switch from internal combustion engine vehicles to electric vehicles (EVs). The automotive sector is one of Europe’s most important industries, providing 6.1% of total EU employment1, building 16.5m passenger vehicles per year and worth a staggering 90.3bln Euros annually. The automotive industry in the UK is also of crucial importance, providing employment for an estimated 186,000 people1 and building 1.6m vehicles per annum.

In order for this vital industry to survive, the switch to EVs must be made quickly, and the necessary battery plants and other infrastructure built as soon as possible. The big problem with this ambitious undertaking is that Europe currently produces no battery grade lithium at all, and hence the race is on to identify suitable sources of domestic supply.

Historically, manufacturers relied on purchasing the necessary raw materials for automotive production anywhere in the world, but this simplistic picture is now clouded by concerns around ethical supply and the carbon footprint of shipping battery raw materials thousands of miles before assembly into a battery pack. Investors in all industries are increasingly worried by such issues and will ultimately withdraw funding should a company not comply with environmental, social and governance hurdles.

Lithium supply is currently dominated by Australia, South America (Chile; Argentina) and China but these sources are geographically distant from Europe. Shipping lithium concentrates to China for processing and then shipping lithium carbonate back to Europe for assembly into a battery is not ideal given the associated carbon footprint. It has been estimated that the raw materials in the battery of an electric vehicle have travelled as much as 50,000km before you even get into the driving seat. To add to the concerns regarding sustainability, the fact that China and the US are currently involved in a bruising trade war has given rise to global concerns over security of supply, especially in Europe given the growing dependence on foreign raw materials.

The question therefore becomes: can Europe, and in our case the UK, source its own secure, sustainable, lithium?

The race is on across Europe to identify possible sources of this metal that was hitherto regarded as a curiosity rather than a metal of vital industrial and national importance. In the case of the UK, it has long been known that lithium is present in the granite that outcrops across Cornwall and Devon but until very recently this had not been considered as a possible economic solution. Unfortunately, mineral exploration in Cornwall has been woefully neglected (except china clay) over the last 30 years since the collapse of the International Tin Council and the consequent collapse of the county’s metal mining industry. This said, the re-evaluation of historical documents in combination with the application of modern knowledge of lithium deposits has indicated great potential for lithium extraction from both brine and hard rock in Cornwall.

Sheeted veins of Li-bearing greisens at Cligga Head, an abandoned W-Sn mine and sample collection from ScotlandThe geology is right

The UK has hitherto been considered as a geological blank spot for lithium, but this is largely a factor of very limited mineral exploration in the country for at least 20 years. The exclusion of the UK as a possible lithium source is despite work in 1864 by Professor Miller of Kings College London indicating that the lithium bearing brines encountered during mining operations in Cornwall could be of importance.

Investigative work on such sources continued until the mid-1990s, possibly due to the need for lithium in atomic weapons. There is anecdotal evidence indicating that lithium minerals were mined in Cornwall during WW2 at Trelavour Downs for chemicals needed for submarine air-conditioning.

The enormous Cornubian granite batholith that underlies most of Cornwall is listed by the US Geological Survey as one of only five large scale lithium enriched granite complexes worldwide and therefore should be considered a prime target for further investigation, however,  there has been no imperative to make this happen. Only now is the real potential becoming recognised and further exploration work is commencing. However, Cornwall isn’t the only location in the UK where lithium containing rocks are present and a recent paper (by Gourcerol et al3) identified potential lithium bearing strata in Fe-Mn deposits in mid Wales and pegmatites in NE Scotland and Northern Ireland. Furthermore, lithium has been historically identified in brines associated with the North Sea oil fields.

Geothermal brines

The presence of high levels of lithium in geothermal brines deep beneath the surface of Cornwall was first identified when Miller sampled water that was ‘issuing in great quantities’ in deep Cornish mines and commented that ‘The occurrence of so large an amount of lithium, being eight or ten times as much per gallon as has been found in any spring hitherto analysed, invests this water with unusual interest and importance.’ Samples of such geothermal springs continued to be taken right up until the closure of Cornwall’s last deep mine in 1998.

In 2016 Cornish Lithium was founded to investigate whether these deep geothermal waters could be a possible source of supply for the UK. The company successfully secured agreements with mineral owners over a large area of Cornwall and has assembled historical and contemporary data into a detailed model of the subsurface in areas which are considered prospective.

The company has also been evaluating the use of newly developed Direct Lithium Extraction (DLE)2 technologies that allow lithium to be extracted from brines in an efficient and environmentally friendly manner without the use of solar evaporation. There are a number of European companies and research organisations actively developing innovative processes for the extraction of lithium, particularly from brines.

An example of this research is that undertaken by Eramet (France) where research is at an advanced stage using an "active solid" to concentrate lithium from the brine. This solid acts like a sponge which is then washed with water to release lithium (in solution) which then undergoes nanofiltration and reverse osmosis. Lithium carbonate is precipitated by reaction with sodium carbonate. Yields of >85% have been achieved in relatively short time spans and the process, developed by Eramet in liaison with IFP Energies Nouvelles and Seprosys, is currently being commercialised. Although developed initially for use with South American brines there is optimism for believing that this or similar innovative technology can be implemented to treat hydrothermal brines found in Europe. Such processes have strong synergies with the geothermal energy industry given that heat can be utilised in the lithium extraction process. A deep geothermal project has this year been drilled in Cornwall may give rise to important synergies between the two industries given the green credentials of lithium and an always on source of renewable power.

Any lithium industry based on extraction from hard rock is likely to focus on lithium bearing mica minerals such as zinnwaldite and petalite given that they are known to occur in various concentrations in the Carnmenellis Granite in Cornwall. While this will create new challenges for mineral processing and extraction, processing options are available, although, inevitably, pilot scale test work will be required to commercialise these routes.

Cornwall Council has indicated a willingness to see a renaissance in mining, therefore providing significant political support. Ongoing studies are evaluating other Li-bearing rocks in the UK but given that Cornwall is already host to a large-scale open-pit china clay mining industry and has a long history of metal mining and it would seem to be the ideal destination for a possible new UK industry focussed on lithium extraction.

National imperative

The UK government, via Innovate UK and the Faraday Battery Challenge Fund, has recently funded a study to examine the possibility of establishing a lithium industry in the UK – from the extraction of suitable minerals right through to battery grade lithium chemicals. This project has been called Lithium for the UK or Li4UK and is a joint study between Wardell Armstrong, the Natural History Museum and Cornish Lithium Ltd.

The project is expected to build upon the experience gained during the EU funded FAME project  - Flexible And Mobile Economic processing technologies - (Euro 7.4mln) which included possible lithium extraction methods in the European context. The Li4UK project began at first principles and conducted a literature search of possible UK occurrences followed by a sampling campaign covering various locations across the UK.

These samples are being analysed to establish mineralogy and lithium tenor. Whilst some interesting occurrences have been identified across the UK the study is expected to focus heavily on Cornwall due to the presence of a large lithium enriched granite and a long-established tradition of mining.

This initial Li4UK work has established that both brine and hard rock sources of lithium exist in the UK, with the hard rock occurrences including spodumene and lithium bearing micas holding zinnwaldite and lepidolite, as well as other lithium bearing minerals such as petalite. A similar picture is emerging in Europe, with spodumene having been identified in Portugal, Finland and Austria and lithium bearing micas having been identified in Germany, Portugal, Spain and the Czech Republic.

Mineral processing techniques to produce lithium mineral concentrates from possible European sources are under evaluation, but relatively little work regarding conversion of these concentrates into battery grade lithium compounds such as lithium carbonate or perhaps more importantly lithium hydroxide has been done. Lithium bearing brines have also been identified in the Rhine Graben area of Germany and the EU has launched a grant funded project into possible extraction from such sources (EuGeLi Project).

Lepidolite froth flotationLithium extraction

Work to identify possible geological sources of lithium is only the first step and this has to be closely followed by work to establish possible extraction methodologies, especially as several European occurrences are currently regarded as unconventional. Commercial lithium chemical processing plants exist in China and Australia (converting Australian spodumene) but there are currently no full-scale commercial conversion plants operating using lithium mica as feed.

The first stage of processing lithium ore is, generally speaking, no different from many other mineral processing techniques and involves physical beneficiation to increase the lithium content. Ores containing lithium bearing minerals including spodumene, lithium micas (lepidolite and zinnwaldite) or other minerals such as petalite or amblygonite, are initially processed using comminution to liberate the individual minerals and the lithium bearing minerals are then separated on the basis of their physical, electrical or magnetic properties, to form a concentrate. Froth flotation and/or magnetic separation can be used to form these concentrates where the Li2O content is increased from the ≈ 1% in the ore to <10%.

Practically all lithium bearing ore minerals in Europe are silicates and hence require chemical processing once physical separation has been achieved. Much research is currently underway to identify suitable processing methods for European ore sources and many different methods have been proposed to recover lithium from hard rock minerals.

The most common methods currently proposed use a combination of roasting (up to 1,100⁰C) and leaching with various chemicals to get lithium into solution. Once soluble, lithium compounds can be precipitated, but it is important to note that the battery industry demands that such compounds are of high purity with battery grade compounds being at least 99.5% pure.

The definition of battery grade is evolving although it is noted that the London metal Exchange (LME) is working towards defining a lithium compound (or compounds – as both lithium carbonate and lithium hydroxide may feature) for LME trading. Given the growing importance of lithium worldwide it is vital that lithium compounds can be freely traded based on definitions of purity, but such standards are still under discussion and it is therefore considered unlikely that LME trading will commence until at least 2020.

Due care

Given recent studies and re-examination of historical data it is now becoming apparent that the UK could host a lithium industry and could supply domestic, and possibly even European, battery demand. Funding for further work to define possible UK sources of supply and the necessary processing methods will have to come from the international investment community, or from government, and as such it is imperative that evaluation work is conducted rigorously and to acceptable global industry standards.

It is therefore vital that work is conducted in a systematic and careful manner with oversight from recognised experts globally. Before detailed exploration commences the necessary sampling, mineralogical testing and assaying procedures must be correctly established, or there is a very real danger that projects will face criticism and ultimately fail. Rushing in to drill holes before such preliminary work is done would be a grave mistake that could threaten the credibility of the entire, nascent, industry.

Author affiliation

1.            Cornish Lithium Limited – Tremough Innovation Centre, Penryn, Cornwall TR10 9TA

2.            Natural History Museum – Cromwell Road, London SW7 5BD

3.            Wardell Armstrong International Limited – 46 Chancery Lane, London WC2A 1JE

Together these three entities comprise the Li4UK Consortium.

Submitted November 2019

References:

1.            European Automobile Manufacturers Association. The Automobile Industry Pocket Guide 2019/20

2.            https://finfeed.com/features/explainer-overview-direct-lithium-extraction-dle-geothermal-brines/

3.            Gourcerol B., Gloaguen E., Melleton J., Tuduri J., Galiegue X.: Re-assessing the European lithium resource potential – A review of hard-rock resources and metallogeny. Ore Geology Reviews, V. 109, June 2019, Pages 494-519. https://doi.org/10.1016/j.oregeorev.2019.04.015