Read the answers to the most frequently asked questions about lithium.
Lithium is the lightest metal. It has the symbol Li and an atomic number of 3, and comes just after hydrogen and helium in the periodic table. The metal is very reactive in its elemental form and is light enough to float in oil, making it an ideal battery material. Lithium metal never occurs freely in nature, and is usually found in ionic minerals such as petalite, lepidolite and spodumene within pegmatite rocks or in solution in salt brines. Despite being an abundant element in the earth’s crust there are few deposits globally where the lithium concentration is sufficient to make economic extraction a possibility. Due to its importance as a component of batteries used in electric vehicles, lithium is a much sought after critical raw material.
In the 1790s on the Swedish isle of Utö, a Brazilian statesman named José Bonifácio de Andrada discovered the first Petalite, a mineral which contained lithium. He was also the first to discover another important lithium containing mineral called spodumene from the same source.
In 1817, Johan August Arfvedson analysed the petalite further and realised it contained a previously unknown metal, which he named lithium. However it wasn’t until 1855 when Augustus Matthiessen, a British chemist, was able to isolate the lightest known metal. Lithium was first discovered in Cornwall in 1864 when saline water from United Mines was analysed by the Professor of Chemistry at Kings College London.
Fast forward to the present day and we find ourselves surrounded by devices powered using small, lightweight and efficient lithium rechargeable batteries. These include laptops and mobile phones, but increasingly electric vehicles and many other digital and electronic devices. It is the use of lithium in electric car batteries and in power storage batteries that is expected to lead to a huge increase in demand for the metal over the coming decades.
Lithium batteries also have a large role to play in renewable energy sources such as wind and solar energy storage, related industries which incidentally already have firm roots within the Cornish landscape.
- Until the commercial development of the lithium-ion battery in 1991, lithium was mainly used in ceramics, pharmaceuticals and other industrial applications. The rapid growth in demand for portable electronics has spurred similar growth in demand for lithium, whereby batteries accounted for approximately 50% of total demand in 2017. This source of demand is expected to grow extremely rapidly given the development of electric vehicles and batteries for power storage: technologies that are widely expected to revolutionise transportation and power distribution in the coming decades. Lithium is the ideal metal for batteries given its high electrode potential and low atomic mass, giving batteries a high charge- and power-to-weight ratio. A fully electric vehicle (such as a Tesla Model S) contains an estimated 63kg of lithium and so the growth and widespread uptake of electric vehicles is driving a global increase in demand for lithium. You can find out more about lithium-ion batteries here.
- As renewable energy sources are increasingly used to generate power, lithium is also used within grid-scale battery storage (required to even-out the supply of energy to the grid).
- It is also used as a flux within the ceramics and glass industries, within greases for lubrication and small amounts are used in the pharmaceuticals industry.
- You can find out more about other applications for lithium here.
- Lithium is found in trace element concentrations in most geological settings: the Earth’s mantle contains 1.6 parts per million (ppm) Li, oceanic crust 4.3 ppm Li and the average concentration in continental crust – the rocks we see at the Earth’s surface – is 20 ppm Li. It is the 30th most abundant element, behind copper but ahead of lead, tin and silver (USGS, 2017). In these trace concentrations, the lithium atoms tend to substitute for other ions (usually magnesium) in common rock-forming minerals, and only forms lithium minerals in rare circumstances. Despite the fact that lithium is a relatively common element it is very rarely found in economic concentrations, hence the global race to identify deposits where lithium can be economically extracted.
- Economic concentrations of lithium can be found in either hard rock sources (e.g. granite or clay) or in solution in lithium-enriched brines (such as the lithium rich salar deposits in Chile and Argentina). Both of these sources are currently exploited around the world but present very different challenges in terms of extraction.
- Table 1. Present and potential sources of lithium worldwide broken down by deposit type (Evans, 2012)
- The map below (Figure 2) which has been produced by the United States Geological Survey (USGS) shows the global distribution of lithium bearing hard rock deposits. These are broken down into lithium rich pegmatite despots (red dots) and lithium-enriched granites (yellow dots). Importantly the granite in Cornwall is one of only five such lithium-enriched granites worldwide (Based on US Geological Survey Lithium Deposit Map)
Lithium is currently extracted from hard rock and from brines. As the demand for lithium has begun to rise due to the development of electric vehicles, new deposits will be needed to fulfil such demand. This will require the development of new extraction methods to unlock ‘new’ deposit types of lithium that haven’t previously been utilised.
Hard rock mining entails drilling and blasting solid rock, before it is collected up, crushed and processed to extract the lithium bearing minerals from the rest of the rock. Lithium extraction from minerals such as spodumene and petalite requires a wide range of specialist processes in order to get lithium into the correct chemical composition and concentration required by the battery industry. Such chemicals are currently either lithium hydroxide or lithium carbonate.
Suitable extraction methods have been developed for many hard-rock deposits, but scientists are currently developing new extraction methods for clay minerals and other potential sources of lithium. Advances in processing techniques for hard rock sources have now made it possible to process other lithium-enriched minerals in hard rock such as zinnwaldite and other micas. The science of suitable extraction methods is still at an early stage but will be driven by the urgent need to commercialise different sources for lithium, especially in Europe.
Lithium-enriched brines form in a variety of geological settings and are largely derived from the contact between fluids and lithium enriched rocks. Lithium is a highly soluble ion and hence tends to leach out of rock into saline water very easily.
“Salar” Brine Deposits
Brines from closed sedimentary basins, such as ‘salar’ brines in South America, contain 58% of the world’s known lithium resources and for many years lithium has been extracted from such brines high in the Chilean Andes. This method requires the salt-rich waters to be pumped to the surface and then in to a series of evaporation ponds where solar evaporation concentrates the lithium brine over a period of around 18 months. Once the brine has become concentrated enough, the solution is pumped in to a recovery plant to first remove unwanted elements such as magnesium and boron, before sodium carbonate is added to precipitate out the lithium carbonate product.
Whilst this is currently an important source of lithium the extraction process relies on solar evaporation, given that the area is extremely arid and remote. Solar evaporation techniques are highly inefficient, generate significant volumes of waste and use large amounts of scarce, highly valuable water.
Figure 4. Solar evaporation brine processing (Lithium Americas)
Geothermal fluids are saline waters that circulate through hot crustal rocks and dissolve elements such as lithium from the rocks into solution. Such fluids were first identified in Cornwall in 1864 when miners looking for tin and copper hit large geological structures containing hot saline water. Given that this was deemed a scientific curiosity these fluids were analysed and found to contain high levels of lithium. Such occurrences were continually monitored and recorded until mining ended in Cornwall in 1998 and the mines where these hot springs had been accessed were flooded.
The presence of lithium enriched geothermal fluids in Cornwall relates to the fact that significant areas of the county are underlain by a very large body of lithium-rich granite. This granite remains hot at depth and has reacted with water circulating in the crust to produce lithium-enriched geothermal fluids which circulate to great depths below ground. Cornish Lithium believes that access to these fluids can be gained via extraction boreholes and that lithium can be extracted at surface in a small processing plant using advanced technologies such as ion-exchange membranes or reverse osmosis. A number of similar proprietary processes have been developed by companies such as Posco, Rincon (formerly Enirgi Group), Veolia, Tenova, PurLucid and Eramet. A typical flowsheet may be as seen in the following figure:
Lithium is our primary focus. However, as we build our knowledge of the geology, structures and mineralisation in Cornwall we are discovering areas which offer very good potential for other metals such as copper, cobalt, tin and other metals which are vital to the development of modern technologies such as batteries.
In its metallic form lithium is highly reactive hence it is never found in this form in nature. Lithium carbonate is the main product produced by the mining industry and is a stable white powder which is considered safe enough to be handled by people.
Lithium is used in small amounts by the pharmaceutical industry as a treatment for bipolar disorder; it is therefore considered safe for consumption in low doses
The environmental impacts depend on the extraction methods used. Cornish Lithium are planning to directly extract the lithium from the fluids in a processing unit that will have a footprint the size of a supermarket or medium sized industrial unit. Direct extraction of lithium from geothermal fluids using cutting-edge technology is the most environmentally responsible method available, and Cornish Lithium will strive to ensure that the impacts of the project are kept to a minimum.
At the United Downs Deep Geothermal Project (UDDGP) which is being developed by Geothermal Engineering Limited (GEL), flow tests have been carried out on the deep geothermal reservoir. Such work is vital in understanding the characteristics of the geothermal system and, as expected, the process generated a number of micro-seismic events in the reservoir at a depth of approximately 5km beneath the surface. All of the events were managed/ controlled by GEL and were within the regulatory limits that govern these types of projects. Press coverage at the time highlighted the importance of geothermal energy to the UK given that experts believe there is enough untapped energy in the granite below Cornwall alone to provide 10 per cent of Britain’s electricity, all of which would be renewable and zero-carbon. For further information, visit GEL’s website, scroll down and click on the Underground (Seismicity) section.