Introduction to Lithium
Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and it must be stored in mineral oil or an inert atmosphere. Due to its reactivity, lithium never occurs freely in nature but is always found in compounds.
Everyday Uses of Lithium
Lithium compounds and the pure metal are integral to various modern technologies and products.
Rechargeable Batteries
One of the most widespread applications of lithium is in rechargeable lithium-ion batteries. These batteries power numerous portable electronic devices, including smartphones from manufacturers such as Apple, Samsung, and Huawei, as well as laptop computers and tablet devices used globally. Lithium-ion batteries are also critical for electric vehicles produced by companies like Tesla, BYD, and Volkswagen, contributing significantly to reduced carbon emissions in transportation systems across continents.
Ceramics and Glass Production
Lithium carbonate and lithium oxide are used as fluxes in the production of high-strength ceramics and specialized glass. The addition of lithium compounds lowers the melting point of silica, reducing energy consumption during manufacturing. This results in more durable and heat-resistant glass and ceramic products, including cookware like CorningWare, certain telescope lenses, and oven doors, which are utilized in households and industries worldwide.
Lubricating Greases
Lithium stearate is a common ingredient in high-performance lubricating greases. These greases are valued for their broad operating temperature range and resistance to water, making them suitable for demanding applications. They are extensively used in automotive components, heavy industrial machinery, and aircraft, ensuring smooth operation and reducing wear and tear in diverse environments from North American factories to Asian mining operations.
Air Purification and Humidity Control
Lithium hydroxide is employed to absorb carbon dioxide in critical environments, such as spacecraft including the International Space Station (ISS) and submarines from various navies. Lithium bromide is utilized in absorption chillers for air conditioning systems, providing dehumidification and cooling in large buildings, hospitals, and industrial facilities in humid climates, for instance, in Southeast Asia or the Caribbean.
Pharmaceutical Applications
Lithium salts, primarily lithium carbonate, are used in psychiatric medicine to treat mood disorders like bipolar disorder. Prescribed under medical supervision, lithium compounds help stabilize mood swings. This therapeutic application is recognized and utilized by healthcare systems globally, providing significant benefits to patients in numerous countries.
Natural Occurrence of Lithium
Lithium is not found as a free element in nature due to its high reactivity. It exists in various minerals and brine deposits around the world.
Lithium is primarily concentrated in two main types of natural sources:
- Brine Deposits: These are underground reservoirs of saltwater highly concentrated with dissolved lithium salts. The largest and most economically significant brine deposits are found in the “Lithium Triangle” of South America, which encompasses the Salar de Atacama in Chile, the Salar de Uyuni in Bolivia, and the Salar del Hombre Muerto in Argentina. Significant brine resources also exist in China and the United States.
- Hard Rock Deposits: Lithium is also found in igneous rocks, particularly within pegmatites, which are coarse-grained intrusive igneous rocks. The most common lithium-bearing mineral is spodumene (LiAlSi2O6). Major hard rock deposits are located in Australia (e.g., Greenbushes mine in Western Australia), Canada (e.g., Quebec), China (e.g., Sichuan province), and the United States (e.g., North Carolina).
Extraction and Industrial Processing
The methods for extracting lithium vary depending on whether it is sourced from brine or hard rock.
Brine Extraction
Extraction from brine typically involves a series of solar evaporation ponds. Brine is pumped from underground reservoirs to the surface and directed into large, shallow ponds. Sunlight and wind naturally evaporate the water, progressively concentrating the lithium salts over months or even years. As the brine concentrates, other salts (like sodium chloride and potassium chloride) precipitate out, leaving a lithium-rich solution. This concentrated solution is then transported to a processing plant where further chemical treatments are applied, often involving the addition of sodium carbonate, to precipitate out lithium carbonate (Li2CO3), a primary industrial lithium product. This process is extensively used in Chile and Argentina.
Hard Rock Mining
For hard rock deposits, minerals such as spodumene are extracted through conventional open-pit or underground mining techniques. The mined ore is then crushed and beneficiated through froth flotation to separate the spodumene from other minerals, yielding a spodumene concentrate. This concentrate is then heated to very high temperatures (roasting) to transform the lithium mineral into a more soluble form. Following roasting, the material is typically leached with sulfuric acid to extract the lithium. The resulting lithium sulfate solution is then purified, and lithium carbonate or lithium hydroxide is precipitated through chemical reactions. This method is prominent in countries like Australia and Canada.