A view into the Trelavour pit. Most of the original roads and berms are still in place allowing for easy rehabilitation.

E&MJ heads to site with the company that’s putting UK lithium extraction on the map

By Carly Leonida, European Editor

For the estimated five million tourists who visit Cornwall, a small county in the far southwest of England, each year, mining is considered a tourist attraction; scars of its industrial past which gave rise to the distinctive engine houses that dot its landscape, and fictional TV characters like Ross Poldark.

The vast majority have no idea that mining is still a vital part of the county’s economy and that the land they stand on provides some of the brightest potential for the UK’s transition to responsibly produced, low-carbon energy technologies.

In June 2023, I made the 480-kilometer (300-mile) journey from London to Falmouth to attend the Sustainable Minerals ’23 conference and learn about cutting-edge developments in the production and recycling of critical minerals.

“There’s a burgeoning mineral extraction industry in Cornwall again, and we all share responsibility for spreading the message and garnering wider public support for what the sector’s doing as part of the renewable energy transition,” Lucy Crane, ESG and Sustainability Manager at Cornish Lithium, told the audience in her keynote presentation.

While critical metals, specifically lithium, only accounts for a tiny sliver of the global market for mined materials, its use in lithium-ion batteries for electric vehicles (EVs) deems it critically important. Current extraction and refining activities are confined to just a handful of countries, some of which carry geopolitical implications for sourcing. S&P Global puts total global lithium supply today at about 960,000 metric tons of lithium carbonate equivalent (LCE) per year (mt/y).

By 2028, which is only five years away, that will need to ramp up to 2 million mt/y of LCE, and this requirement is expected to double by 2030 as EV production kicks into gear. Based on that, the mineral extraction industry will need to bring on about 250,000 mt of new supply each year. With an average time of 16 years from discovery to production for most resources, that’s going to be difficult… but not impossible.

“Given these challenges, we need to look for new mineral deposits in more remote places, to consider deposit types that weren’t previously considered economically viable, and to apply innovative technologies to extract them,” said Crane.

Cornish Lithium is doing all of the above. For a more in depth look at its plans, I joined Crane at Trelavour, the company’s open-pit lithium project near St Austell.

“We’re reevaluating Cornwall in light of the energy transition, seeing which minerals are present and if they could potentially be extracted,” she told me as we toured the facility. “Lithium is our key focus at the moment and we aim to provide a responsible domestic supply. In the UK, the automotive sector is really important to the economy, it directly and indirectly supports around 860,000 jobs.

“With the new EU rules of origin coming into force, the UK government needs to be more proactive at supporting that industry if it wants to keep those jobs. To qualify for low or tariff-free trade with the EU, a lot of the value within EVs — namely the batteries — must be produced in the UK. If we can extract some of those materials domestically, then that’s only going to be a positive thing, both from a geopolitical and a carbon footprint perspective.”

A third drilling campaign is currently underway in the pit.

The Cornish Advantage

Cornish Lithium’s business model is two-pronged: first, it has a hard rock, open-pit extraction project — Trelavour in North Cornwall. And second, it’s investigating the extraction of lithium from geothermal brines — hot ground waters which circulate at depth through the fractured granites that make up the Cornubian batholith — at a clutch of other sites.

“The contexts of these projects are very different,” Crane explained. “But the principles are the same — to apply innovative technologies to create a local and sustainable source of lithium to support British manufacturing. We can extract lithium from both micas and geothermal waters. There are a few projects in China that are using direct lithium extraction (DLE) technology to produce lithium from brines at a commercial scale, but no one is doing it domestically yet. We hope to be the first. With little to no wastage and low impact on the environment, the DLE process utilized is sustainable and has a low carbon footprint.”

Cornish Lithium is currently a privately owned company. It has mineral rights agreements in place across a good chunk of Cornwall (in the UK, mineral rights are privately held). Around 600 km2 of these are onshore, including some with the Tregothnan Estate, and approximately 400 km2 are situated offshore. Its CEO, Jeremy Wrathall made their acquisition a priority after establishing the company in 2016, so it has an early mover advantage in that sense.

“We know that the geological structures we’re investigating host geothermal waters at depth, and we know that those structures extend offshore for tens of kilometers” Crane explained. “We have a 10-year agreement with the Crown Estate for the offshore rights that we’re about 18 months into and, over time, we’ll whittle the search areas down. We’re currently doing desktop studies and are very mindful of proving the processes and technologies onshore before even considering their application offshore. It just gives us more optionality.”

The Cornish Lithium team currently comprises around 70 people, most of whom are based in Cornwall, although the corporate team is situated in London. The company has raised approximately £20 million (US$25.5 million) in seed investment, including through three rounds of crowd funding, which gave local community members a chance to take a stake in the business.

“We’re going through another financing round at the moment. A private equity fund called TechMet joined us as an investor about 18 months ago, and their focus is investing in clean energy technologies. It’s great that investors are expanding their scope to incorporate mining as part of the solution to climate change,” said Crane.

Cornish Lithium is investigating whether water from the flooded Trelavour pit could be treated and fed into local water supplies.

Mining Never Really Left

Most people associate mining in Cornwall with metals like tin, copper and tungsten. While these elements and their mineralization drove the golden age of British mining from the 1700s until the last tin mine — South Crofty — closed its doors in 1998, mining for other minerals has persisted and continues to be an important part of the Cornish economy.

Granites underly much of southwest England and, where they outcrop at the surface, some have undergone a weathering process called kaolinization. The resulting kaolin (aka china clay) is a vital component in ceramics, medicine and even cosmetics. Twenty years ago, approximately 10,000 people across Cornwall were directly employed by the mining industry. That number has now fallen to around 700, although Cornish Lithium has high hopes that its operations and the growth of neighboring companies, like Cornish Metals and British Lithium, will trigger a revival.

“Mining has a really big multiplier effect in terms of employment,” said Crane. “It’s estimated that for every person employed directly by mining, a further 3-6 indirect jobs are created in areas such as services, consultancy and equipment.”

This can only be a good thing given that, according to Eurostat (the European Union’s data agency), Cornwall is the second poorest region in the whole of northern Europe.

“From our perspective, it’s a good place to be, because there’s still a huge amount of mining expertise in Cornwall despite the decline in employment,” said Crane. “There are over 100 local consultancy and service companies in the Cornwall Mining Alliance and we’ve got the Camborne School of Mines — one of the best mining schools in the world — right on our doorstep. The mining community here is still very strong.”

A drilling contractor at work at Trelavour.

Reinvigorating Trelavour and Trelith

Trelavour, Cornish Lithium’s flagship hard-rock project, is a brownfield site. The associated processing plant, which is called Trelith, adjoins the Parkandillack processing site which belongs to china clay behemoth, Imerys. It was once the operation’s bleaching and bagging plant and this works in Cornish Lithium’s favor, because much of the infrastructure, including buildings and an underutilized rail line, are still in good shape and ready to be reconditioned.

The Trelavour pit sits approximately 500 m away from Trelith and is still classed as an operational mine which, from a planning and social licensing perspective, makes restarting the operation simpler.

“We’re currently doing our third round of drilling in the pit,” said Crane. “The first two rounds of reverse circulation and diamond drilling fed into the scoping study that we produced in 2022, and we’re adding another round to increase our confidence in the resource and obtain further geotechnical information.”

She added that there are environmental and economic benefits to Trelavour being an existing pit. Firstly, the company won’t be disturbing a virgin environment.

Crane explained: “We recently employed a full-time ecologist alongside working with local environmental consultancies to conduct baseline assessments of the site. That data is important, because we want to do right by both people and the environment from the get-go. Also, from a financial perspective, a lot of the groundwork in the pit has already been done for us; many of the haul roads and berms already exist and can be rehabilitated with relatively low investment. We’ve done a substantial amount of work already.

“The railway line at Trelith also needs some work, but it connects to the mainline with options for easy access to industrial docks at Falmouth, Plymouth and Fowey which, ideally, we’ll use for shipping our lithium hydroxide product.”

Tata, owner of British automotive manufacturer, Jaguar Land Rover, recently confirmed plans to build an EV battery gigafactory at the Gravity Business Park in Somerset which sits about 160 km northeast of Trelith. It’s a good example of a potential future customer.

The onsite lab at United Downs, Cornish Lithium’s flagship geothermal project.

“There’s also decent power supply to this whole area and a high number of renewable energy projects nearby too,” said Crane. “We’re looking at power purchase agreements with the ambition of wholly powering Trelavour and Trelith with renewable energy but, in a worst-case scenario, the grid in Cornwall is supplied with approximately 40% renewable energy anyway.

“To keep the carbon footprint and local traffic low, we’re looking at options like using conveyors between the pit and processing site, situating the primary crusher in the pit, and maybe even a fleet of battery-electric vehicles.”

Harnessing Innovative Technologies

The resource defined in Cornish Lithium’s 2022 scoping study stands at 51.7 million mt at 0.24% lithium oxide — that’s roughly 300,000 mt of LCE. It has a low- to zero-strip ratio and the lithium-rich G5 granite which the company is targeting lies mainly in the top 200 m of material, which lends itself perfectly to open-pit extraction.

The company is currently engaging consultants for the environmental and social impact assessment (ESIA) and feasibility studies, work on which will kick off in the fall. Over a 20-year mine life, the project aims to produce around 8,000 mt/y of battery-grade lithium hydroxide. The Faraday Institute estimates that the UK alone will need 80,000 mt/y of lithium by 2030, so Trelavour could potentially account for 10% of UK supply.

The brines are stored in bowsers before and after testing.

“The UK will still need to import lithium but, if we can reduce the impact of that by 10%, then so much the better,” said Crane. “Something we’re really keen on is being as resource efficient as possible.

“We want to build circular economy into our operations from day one, so we’re investigating markets for potential byproducts, including kaolin, the quality of which we’ve already tested with Imerys. Aggregates could also be produced from the first stage of processing — which constitutes crushing grinding, froth flotation and separation — and then the L-Max process, which forms our second stage of processing, will allow us to produce cesium, potash, amorphous silica and gypsum too.”

L-Max was developed by Australian firm, Lepidico, to extract lithium from lepidolite and other lithium micas. Cornish Lithium has an exclusive license to use the technology across the St Austell area. Following concentration, the mica is subject to leaching. The lithium salts are brought into solution and then selectively precipitated by adjusting its temperature and pH. The benefits of L-Max include its low energy requirements, it only uses low-cost, conventional reagents like sulphuric acid and lime as well as steam, and it employs commonly used industrial equipment. It also does away with the need for high-temperature roasting which would increase the operation’s carbon footprint significantly.

“We’re doing some tests to see whether the by-product fines could be used in producing marine concrete for the offshore wind industry as well,” Crane added. “The feedback we’ve had from investors so far is that they’re impressed with how much detail we’ve gone into at this early stage. Details on mineral processing are not usually required at the scoping stage.”

Lepidico is currently scaling up an L-Max plant at a site in Namibia, and Crane said that Cornish Lithium has been able to learn a lot from watching that project.

“We also received some funding from the UK Government in 2022 to build a demonstration scale L-Max plant here at Trelith,” she told me. “The equipment is arriving over the next six months, and we’ll be trial mining about 1,000 mt of material to put through that. The plan is to have the plant operational for 3-4 months by mid-2024. That will allow us to run the process continuously and de-risk the technology for when we scale up to a commercial sized plant.”

That test work, which is covered by current Cornish Lithium’s current permits, is also the reason why the company is able to skip the prefeasibility stage and head straight to a feasibility study which, again, will speed development significantly.

“It’s an ambitious schedule for design and construction,” said Crane. “We’re aiming to reach production by the end
of 2026.”

From Hard Rock to Water

Over many millennia, the granite (and country rock) that underlies much of Cornwall has been subject to various episodes of faulting and mineralization. As saline geothermal brines coursed (and continue to course) through these faults, they precipitated valuable minerals forming pockets, or lodes, of mineralization.

The faults and vein sets which trend northeast-southwest are associated with the tin and copper mineralization which put Cornish mining on the map. A perpendicular set of faults crosscut these areas of mineralization — hence their colloquial name ‘cross courses’ — and these were more recently reactivated than the main tin and copper lodes which they cross.

Cornish Lithium is currently investigating different combinations of DLE and water treatment technologies. The rigs are setup in shipping containers for ease of movement.

It’s these cross courses and the waters that flow through them that are responsible for the aforementioned engine houses which people the world over associate with Cornish mines; as underground tin and copper operations intersected these faults during the 1700s and 1800s, geothermal waters filled the lower mine workings and needed to be pumped out for both practical and safety reasons.

“It was a welfare issue,” Crane explained. “Because of the stifling heat and humidity and lack of ventilation, some of the deeper levels could only be worked for 15 minutes at a time, and so mines began to document where these hot springs occurred as well as their temperatures and flowrates. In 1864, Professor Miller from King’s College in London took a sample from one of the hot springs at United Downs — the area was being worked by United Mines at the time — analyzed it and wrote an academic paper which stated that these hot springs could be a potential source of lithium.

“We know now that lithium is hosted in the geothermal waters which are flowing through the permeable structures cutting the granite, and we believe that they become enriched as a result of flowing through the lithium-enriched granite. The lithium is leached from the surrounding rock into solution, and is present as dissolved lithium chloride.”

To date, Cornish Lithium has drilled three geothermal boreholes to test and prove its theory. The first two are at United Downs — the company’s flagship geothermal site, near to the town of Redruth. These were diamond-core drilled in 2019 to approximately 1 km depth, initially to test one geological structure that was known to be highly permeable. However, the area was more prospective than anticipated, and the company ended up testing eight permeable intervals, sampling waters from each of them, and downhole wireline tests were run to capture additional geological information.

Following this, the search area was widened, and a third borehole drilled in 2022 at Twelveheads, a site near Chacewater, approximately 3 km from United Downs. This hole was drilled to nearly 2 km depth and targeted a particular geological structure that was thought to intersect the borehole at 1,600m. The exploration area has now been stepped out again and, when I visited in early June, drilling at Cornish Lithium’s Blackwater site stood at around 700 m depth.

“The sites are staggered across a 5 km radius from United Downs, and the idea is to demonstrate regional prospectivity,” Crane explained. “In addition to sampling the geothermal waters, we’re also undertaking all the classic mineral exploration activities like core logging, so we have a complete picture of the geothermal system.

“Our concept, in simplified terms, is to drill boreholes to between 1.5 and 2 km depth, pump these fluids to the surface, and put them through a DLE plant and also a heat exchanger, because at that depth, the waters are around 70°C. That heat could be used by local businesses or to heat glass houses for food production.”

Lithium from ‘deep’ geothermal waters (over 5 km) are even hotter, which means there is potential for the production of zero-carbon electricity which could be used to power DLE plants for zero-carbon lithium production.

Finding the Optimal DLE Setup

Each of Cornish Lithium’s geothermal sites (of which there are currently four) will eventually produce about 500 to 1,000 mt/y of lithium which, for one site is relatively small, but cumulatively, it’s significant and, importantly, it’s a model that’s scalable.

“We want to have a number of low-impact, low-footprint operations dotted across Cornwall, ideally on the edge of brownfield sites like industrial estates,” Crane told me.

Core samples showing the clear difference in geological structure between the competent granites (right hand cores) and the permeable quartz-rich veins which cross cut them (left hand cores).

She added that Cornish Lithium has been trialling different combinations of DLE and water treatment technologies to find a combination that best suits the geothermal brines they’re handling.

“We received some funding two years ago for this, and initially we tried an ion exchange technology from a French company called Geolith,” she said. “We were pleased with the results, and we’re now testing some adsorption and reverse osmosis technologies too with the aim of building our ideal flowsheet. We’ve got the technologies setup in a series of shipping containers at United Downs. They’re modular so can be swapped out easily, and all of the technologies apart from the DLE element are fairly standard.

“What we’ve found so far, is that the optimal technology setup is very context specific. So, what works best on a Cornish geothermal water is likely going to be different to what works on French or Californian geothermal waters. It’s highly dependent on the salinity and the total dissolved solids.”

There are DLE technologies out there that are suited to high salinity, but the waters Cornish Lithium has tested to date have quite low salinity levels (lower than seawater, for instance) and, while they contain elevated levels of lithium, they have relatively low levels of calcium and other cations, which is helpful when the aim is to selectively remove one element.

The DLE part of the process is essentially a purification step for the lithium chloride and then reverse osmosis is used to concentrate it. Once batch testing of the chosen flowsheet has been proven, the plan is to build a demonstration plant in the next 18 months (permit depending) to allow continuous testing to be evaluated.

Initially, Cornish Lithium plans to sell the lithium chloride concentrate straight, as there’s already domestic demand for this product.

“We’re doing some economic modelling at the moment,” said Crane. “Once we’ve got five or more of these plants up and running, and we’re producing about 5,000 mt/y of lithium chloride, then it might make sense for us to do secondary refining ourselves.”

Crane also announced in her Sustainable Minerals ‘23 presentation that Cornish Lithium has signed on as a partner for the ReBlend project, one stream of which aims to test if DLE technologies could potentially be used to extract lithium from black mass in battery recycling. The company is providing geothermal brine to the project, as well as inputting DLE expertise, which ties in perfectly with its focus on research and innovation as well as circular economy.

A sample of granite displaying a high degree of faulting and mineralization.

Putting ESG First

Cornish Lithium is now working alongside the UK Environment Agency and hydrogeologists to determine what to do with the geothermal waters post-extraction. Because only the lithium ions will be removed, there is relatively little change to their chemical composition, and so the waters could potentially be reinjected into the boreholes or used to create a source of potable water.

The old Trelavour pit is currently flooded, and the company is also investigating whether that large volume of water could potentially benefit local communities rather than being discharged into the local water system; the county, which is famed for its green landscapes, is experiencing an extended drought and potential new water supplies are not to be dismissed.

“It’s great that the innovative technologies we’re testing could help to bring us closer to local communities, and engagement continues to be a really important part of the design process,” said Crane. “We’re running regular drop-in sessions so that people can come and learn more about us and what we’re doing, and we take a stand at the Royal Cornwall Show — a local agricultural event — alongside a number of other local events each year, so that people can come and meet us and ask questions.”

In 2022, Cornish Lithium invested £41,000 into local community projects and initiatives, and it has a similar sized budget for 2023.

“We try to employ as many local people as possible, and we’ve got a procurement policy which prioritizes local suppliers,” added Crane. “We recently engaged E4Tech, a sustainability consultancy, to do a gross value-add calculation for us. They estimated that, once in production, Trelavour alone would add about £800 million in gross value add (GVA) directly to the Cornish economy, and there will of course be indirect value added too.”

A 20-year mine life not only offers people from the local area a chance to learn valuable skills and have a sustainable career locally; but given that a host of new mining projects are in various stages of design and development across England by the likes of Cornish Metals, British Lithium and Northern Lithium, that experience could also allow employment elsewhere in the UK too.

“We also have an extensive schools outreach program to encourage younger generations into mining,” Crane added proudly. “We’re working really hard to educate people, not only about what we’re doing, but also to open their eyes to the future opportunities that the mining industry can offer.”