Lithium (Li, atomic no. 3) is a soft and lustrous metal with the lowest density of all metals. Often referred to as ‘white gold’ due to its market value and silver colour, it reacts vigorously with water. Lightest of the all solid elements, Lithium is toxic except in very small doses.
Lithium is abundant in the Earth’s crust but is very finely distributed. It is found combined in small amounts in nearly all igneous rocks and in the waters of many mineral springs. The concentration of lithium in seawater is 0.1 parts per million (ppm).
Lithium is critical in the context of modern technology development and the transition to clean energy as it is used in electronic devices, computer, and information and technology (IT) devices like laptops, cell phones, and electric and hybrid vehicles.
Discovered in 1817 by Johan August Arfwedson, a Swedish chemist, in the mineral petalite, lithium is found in mostly salt-flat brine deposits (continental brine deposits) and as salts in mineral springs; hard rock mineral pegmatite ores such as spodumene, lepidolite, and amblygonite; and sedimentary rocks. Continental brines and pegmatites are the main sources of lithium for commercial production.
Theoretically, lithium can also be extracted from lithium clays (the commercial scale production of lithium is yet to be realised).
Lithium in its occurrence is geographically restricted. It is mainly found in hard-rock ores of Australia and China; continental brine deposits (salars) of salt pans in South America—the Lithium Triangle (region of the Andes near the borders of Bolivia, Chile, and Argentina along the Atacama desert and neighbouring arid places); and China.
Continental brine deposits are more abundant than hard rock ores: the former represent about 60 per cent of global lithium resources though only about 40 per cent of production (as of 2022).
Bolivia leads with 21 million metric tonnes of lithium resources (as of 2021) but with no mines. Argentina follows with 19 million metric tonnes (6,200 mines) and Chile, produces around 9.8 million metric tonnes (26,000 mines). India has the sixth spot with 5.9 million metric tonnes of resources but with no mines.
Uses of Lithium
Of the lithium concentrates, chemical grade lithium is used to produce lithium chemicals which form the basis for the manufacture of lithium-ion batteries for laptops, mobile phones, and electric cars while the technical grade lithium is used in the manufacture of glass, ceramics, and heat-proof cookware.
The principal applications of the lithium metal are as follows.
- In metallurgy, active lithium is used as a scavenger element for the removal of non-metallic impurities such as oxygen, nitrogen, hydrogen, and carbon elements when refining metals like iron, nickel, and copper.
- Lithium metal is made into alloys with aluminium and magnesium for armour plating, aircraft, bicycle frames, and high-speed trains.
- It is used in organic synthesis to produce compounds like n-butyllithium (C4H9Li) an initiator of polymerisation for the production of synthetic rubber and other organic products such as pharmaceuticals.
- High-power rechargeable lithium storage batteries are used in electric vehicles and for power storage; smaller rechargeable lithium batteries are extensively used for cell phones, cameras, and other electronic devices.
Lithium is used as a coolant in heat transfer applications, especially in nuclear processes, with lithium-6 and lithium-7 isotopes used in the production of tritium and making solid fusion fuels used in hydrogen bombs (as lithium deuteride).
- Lithium is used in ceramics and glass industries; as a flux in silica processing (lithium oxide) and to make oven wares and lab wares; for storing hydrogen as a fuel (lithium hydride); as sorbents for gas streams (lithium chloride and lithium bromide); and for manufacturing optics for visibility in infra-red, ultra-violet, and vacuum ultraviolet ranges (lithium fluoride).
In green technologies lithium is crucial in the transition to renewable energy development.
As it is highly reactive and relatively light, lithium is ideal for clean technologies such as batteries in electric and hybrid vehicles—an alternative to fossil fuel-using motor transport that emit CO2 and other greenhouse gases. Lithium batteries from lithium carbonate or lithium hydroxide can store a large amount of energy in a small space and have efficient charging capabilities. Currently, batteries use around 39 per cent of total lithium production while the rest goes into ceramics and glass, lubricating greases, and medical and other applications.
Lithium energy storage capabilities make it useful for grid storage of renewable energy (solar and wind power) so that it can be stored and used as and when needed.
Some Facts about Lithium
Though lithium has no biological role, it leads the modern industrial and technological development trend.
In 2016, 43,000 metric tonnes of lithium were mined worldwide: this figure was three times higher by 2022, and by 2030, the amount mined could increase more than quadruple again.
Approximately, 2.2 million litres of water is needed to produce 1000 kg (one tonne) of lithium.
Not much lithium goes into the production of single items: a 300-kg battery (50 kWh) of a mid-sized model electric car contains only around eight kilograms of the metal.
The CO2 emissions for manufacturing an 80-kWh lithium-ion battery for the Tesla Model 3 would range very high between 2,400 kg and 16,000 kg.
Environmental Impact from Lithium Extraction
The environmental damage from the extraction of lithium begins at the preliminary stage itself: the energy to extract and process lithium from ores/brines mostly comes from CO2-emitting fossil fuels.
Various methods are used to extract lithium from rock mineral ores of spodumene, lepidolite, petalite, and zinnwaldite through acid, alkali, chlorination, and salt roasting.
Though rock mineral ores give lithium of higher quality (compared to brine), allow greater flexibility in processing and faster processing, and utilise low-cost traditional mining techniques, lithium extraction from them has some major disadvantages—it is a labour-intensive process; there is higher resource consumption intensity such as of sulphuric acid/sulphate, calcium oxide, and sodium carbonate; there is high pollutant discharge; it consumes lot of energy and a large amount of water.
The brine deposits are of three kinds: continental (salars or salt flats) geothermal brines, and oil fields.
The salar evaporation method is used to extract lithium from brine in salars or salt lakes. Brine is pumped from underground reservoirs into open air ponds, in which over 90 per cent of the original water content is lost through evaporation. The evaporation takes place in a succession of ponds. The concentrated brines are then transferred to a chemical plant for refining, the final product being lithium carbonate (Li2CO3).
Production from brine deposits is seen as the most effective, sustainable, and low-cost lithium production process today, but it has many disadvantages, such as using large volumes of water; pumping out brine lowering groundwater levels, while river courses and wetlands can dry up and lead to desertification; longer time to market the lithium mined due to longer build time and a long evaporation process; low lithium concentration derived; and the extraction process leaving behind hills of salt that contaminate the environment with toxic chemicals like diesel, magnesium, lime, and polyvinyl chloride (PVC).
Towards Minimising Environmental Damage: Exploring Options
The growth in clean and renewable energy use has increased the demand for lithium. So drastic advancements in lithium extraction sources and particularly technologies have become necessary.
In the future, saving lithium through recycling and sales would become necessary though not much recycling is done as of now.
Lithium mining from geothermal brines Geothermal brine is a hot, concentrated saline solution that has circulated through very hot rocks (due to high heat flow) and become enriched with elements including lithium, potassium, and boron. Geothermal brine waters are accessed via boreholes and they are pumped to the surface to extract lithium compounds using direct lithium extraction (DLE) technologies.
Geothermal lithium brines are found mostly in New Zealand, Iceland, Chile, and Germany (in the vicinity of densely populated areas).
Lithium extracted from geothermal brines is seen as a low-carbon alternative to lithium extraction from other sources. The energy for the extraction process comes from deep geothermal energy itself, so it is climate-neutral. However, along with oil brines, these brines have lower lithium concentrations and their occurrence is scarce (each of them accounts for only three per cent of the known global lithium resources).
The much-developed open evaporation technology cannot be used for extracting lithium from these dilute brines. Industrial plants for lithium extraction from geothermal brines do not exist on a large industrial scale.
DLE technologies Using DLE technologies to extract lithium from underground brines (solar and geothermal) does away with heavy use of fossil fuels and highly energy intensive processes in extraction. There are as many as 60 variants of DLE technology.
Some of the main DLE methods are as follows:
- Ion exchange systems separate ionic contaminants from solution through a physical-chemical process where undesirable ions are replaced by other ions of the same electrical charge. Essentially, the ion-exchange material acts as a sieve with an adjusted porosity that only allows lithium (and hydrogen) ions to pass through. The ion-sieve can then be washed with an acidic solution promoting the replacement of lithium ions with hydrogen ions.
- In adsorption, the most developed DLE technology, lithium chloride (LiCl) molecules are removed from the brine infiltrate within the atomic layers of an adsorbent. Some sorbents developed can recover over 90 per cent of the lithium present, without the need for an acid wash or other chemicals.
- Solvent or liquid-liquid extraction involves an organic solution (containing solvent and extractant) to extract lithium from brines either chemically or physically and transforming it into LiCl (or ions).
- Membrane-based technologies for lithium recovery use a combination of membrane processes such as nanofiltration, selective electrodialysis, and membrane distillation crystallisation. These, along with a conventional lithium precipitation process, can lead to lower cost of lithium extraction.
- Other methods include electrochemical ion pumping and thermal-assisted methods for brine concentration other than open air evaporation.
Lithium can be extracted from geothermal brines using DLE methods like solvents designed to collect lithium ions, membranes that only allow lithium ions to pass, electrochemical separation where lithium ions are drawn to charged electrodes, and adsorption of lithium using inorganic sorbents.
DLE has the potential to significantly:
- increase the supply of lithium from brine projects, nearly doubling lithium production with sustainability benefits;
- reduce the overall amount of time needed for the lithium extraction process;
- reduce the amount of fresh water used; and
- have a lower carbon footprint than traditional extraction methods.
The main drawbacks include
- the need to control and remove other materials in the brine that potentially interfere with the lithium extraction process (such as sodium and magnesium);
- unproven commercial viability of most DLE technologies; and
- where underground brines or freshwater are pumped to the surface, irreversible damage if connections between different groundwater aquifers, or between groundwater aquifers and surface waters, are not taken into account.
India
India is import-dependent for several elements such as lithium, nickel, and cobalt. India imported around Rs 26,000 crore of lithium between 2018 and 2021.
Lithium resources have been identified for mining but processing from these sources has not been initiated.
In 2021, preliminary surveys by the Atomic Minerals Directorate for Exploration and Research (AMD) indicated the presence of lithium resources of 1,600 tonnes in the Mandya district of Karnataka. In February 2023, the Geological Survey of India announced the discovery of some 5.9 million metric tonnes of lithium resources in the mountainous Salal-Haimana area, Reasi district, Jammu. The site has been identified as an ‘inferred resource’ of the metal, i.e., at a preliminary exploration stage.
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