Air Conditioners / Gas and Air Treatment
Concentrated lithium bromide brines (54 %) are widely used in aqueous solution as an absorption medium in industrial absorption refrigeration systems. The principle is based on the latent heat involved in the transfer of water between the vapor and the liquid phase. The solution can almost be recycled indefinitely, since the lithium bromide itself is stable. This technology is gaining in importance, since it is a viable substitute for chlorofluorocarbons which are known to be detrimental to the ozone layer.
These refrigerating units are used mainly in hotels, apartment buildings, hospitals, etc. for air conditioning and process cooling.
Similarly, lithium chloride solutions are used in industrial humidity control and drying systems of comparable construction. They are largely used in photographic processing, laboratories, food processing, pharmaceutical manufacturing, etc. These systems have the added advantage that the lithium chloride destroys microorganisms, bacteria, etc.
Such aqueous solutions in absorption machines are corrosive and therefore inhibitors, such as lithium chromate, lithium nitrate or lithium molybdate, need to be added.
Anhydrous lithium hydroxide and peroxide serve for the removal of carbon dioxide from the air. They are used specifically in closed systems such as submarines and space shuttles.
Numerous aluminum smelters in the world add lithium carbonate (1 - 3 %) to the cryolite (Na3AlF6) bath to realize several benefits: reduction of the bath temperature as well as energy savings through higher conductivity and lower viscosity. The production capacity of a smelter can be slightly increased at the same operating conditions. However, the environmental benefits are even more important: the fluorine emissions can be reduced by 20 to 30 % allowing conformance to higher standards. The more modern facilities use a more acidic bath (high AlF3) composition instead and better scrubbing systems. These facilities do not require the addition of lithium.
Both pure and doped (with beryllium or strontium) lithium tetraborate and metaborate are used as fluxing agents for the quality control of cements and ores functioning as an internal standard in X-ray spectroscopy and optical emission analysis.
Batteries and Accumulators
Besides the well known application of lithium metal in primary lithium batteries (anode material for high energy density cells), numerous lithium salts are used as electrolytes in primary and secondary lithium batteries. These salts include lithium chloride, bromide, iodide, perchlorate, and nitride. In nickel metal hydride accumulators, lithium hydroxide maintains the conductivity of the electrolyte by precipitating carbon dioxide as lithium carbonate.
Several lithium salts such as lithium carbonate, lithium sulfate and lithium hydroxide are used as additives for fast setting cements, floor screeds, joint sealing mortars, and cement based adhesives. These lithium compounds accelerate the setting and hardening of aqueous binding systems based on high alumina cement. This is of particular importance when other additives used in formulations have the disadvantage of retarding the hardening process below the actual required properties.
Dyes and Pigments
Lithium hydroxide finds application as an additive for dyestuffs as well as increasing the brilliance for specific pigments.
A very high purity lithium carbonate is manufactured for solid ion conductors and monocrystals used in the electronics industry. Such carbonate is furthermore a source of a raw material for the production of anode material used in lithium ion batteries (lithium cobalt oxide, lithium manganese oxide).
The use of lithium carbonate in the enamel, ceramic and glass industry has become a major industrial application. Lithium oxide (Li2O) is formed in the glass. It is beneficial to the melting process since it decreases the melting point, viscosity, and thermal expansion. Additional benefits include improvement of the chemical durability, density and workability. One well-known application is the manufacture of glass ceramic cooking ranges. Lithium oxide shows the same properties in enamels and ceramics. Optical glass ceramics for high performance telescopes require extremely low linear thermal expansion. Once again lithium carbonate finds application in this field. A famous example is the manufacture of the very large telescope (VLT) which has been manufactured in Germany. In addition to the carbonate other lithium salts such as chloride, fluoride, phosphate, silicate or sulfates are also used in specific applications.
This is the largest industrial application for lithium hydroxide. Lithium hydroxide serves to produce lithium stearate, mainly lithium 12-hydroxy-stearate. Such high temperature resistant greases show good viscosity properties up to 200 °C and are widely used in motor vehicles, aircraft and heavy machinery. Their main advantage is water resistance and a wide range of working temperatures.
A traditional application for lithium metal rods is degassing copper, rods of lithium metal, packed in copper cartridges are also used for oxidizing the impurities in a liquid copper bath. Lithium chloride and fluoride can be used as an additive to salt baths for dip brazing and open furnace soldering. The carbonate is used in welding powders and welding rod coatings.
Lithium niobate is one of the most versatile and well-developed active optical materials. The crystal finds wide application in electro-optics, acousto-optics, nonlinear optics and guided-wave optics. Fundamental properties making lithium niobate suitable for such uses include a wide transparency range, high electro-optic and nonlinear optic coefficients, very high electro-mechanical coupling coefficients, and chemical and mechanical stability.
Specific optical products, such as windows for spectroscopy, use lithium carbonate or fluoride in the glasses composition.
Organic Chemistry and Pharmaceutical Industry
A wide range of lithium products are used as versatile chemical tools for the synthesis of pharmaceuticals, agrochemicals, flavors, fragrances and other organic intermediates. Compounds containing a carbon-Li bond serve as strong, nucleophilic bases to generate carbanions by proton abstraction and lithium-halide exchange. The most commonly used reagents are butyllithium and hexyllithium which are available on a large industrial scale. Special organolithium compounds like methyllithium, phenyllithium and lithiumacetylide-ethylendiamine can be used for the introduction of the corresponding organic group. Organolithium amides like lithium diisopropylamide (LDA) or lithium-bis(trimethylsilyl)amide (LHMDS or LiNSi) are also strong bases, but in contrast to butyllithium, are non-nucleophilic. The classic reaction with these bases is the formation of an enolate. Broad variety of Grignard reagents is used for the introduction of the corresponding alkyl or aryl group as well as special sterically hindered alkali metal alkoxides. Lithium metal, dissolved in liquid ammonia, is a versatile reducing agent for the partial reduction of aromatics especially in the preparation of steroids and vitamins. Other wide application are hydrides.
Lithium salts can also be useful for synthetic organic transformations. Lithium amide is used as a base for condensation and alkylation reactions, lithium bromide allows dehydrohalgenations and lithium hydroxide can be used for saponification reactions. Some lithium salts are active ingredients used in the pharmaceutical industry for the treatment of maniac depressive (Bipolar) diseases. The most important product of this category is lithium carbonate pharmaceutical grade.
Several lithium salts are used in photographic developers. These include lithium chloride, sulfate and sulfite.
Rubber and Plastics
One of the largest industrial applications of butyllithium is its well-known property as an initiator for anionic polymerization reaction leading to various types of synthetic rubbers and plastics. One of the major applications is the production of low styrene-butadiene-styrene copolymers (SBS) which are used mainly in the manufacture of footwear. These polymers are also used in the formulation of bitumen (road pavement and roofs) as additive in polystyrene (makes it softer and increases the crack resistance) as well as adhesives. When the styrene content is in the range of 70 % the product is no longer considered an elastomer, showing plastic properties. These high styrene polymers are used for medical components, toys, food packaging, cups and garment hangers, etc.
Nuclear fusion is a process in which light nuclei fuse together to form heavier ones: during this process a very large amount of energy is released. In the core of the Sun, the lightest and most abundant element hydrogen, is converted into helium at a temperature of 15 million degrees. Because of its low reactivity cross section this reaction is not relevant on earth. Hence for a fusion reactor it is planned to use instead the two isotopes of hydrogen: deuterium (D) and tritium (T), which fuse together much more readily than any other combination of light nuclei according to the following reaction:
D2 + T3 → He4 + n + 17.6 MeV
Deuterium is very abundant on the earth and can be extracted from water (0.034 g/L). One liter of water contains the equivalent energy of 300 L of petroleum fuel. Tritium does not occur naturally but it can be produced from lithium using the neutrons from the D-T fusion reactions. The two isotopes of natural lithium contribute to this breeding of tritium according to the reactions:
Li6 + n → He4 + T3 + 4.8 MeV
Li7 + n → He4 + T3 + n - 2.5 MeV
The global reaction, for D-T, then becomes:
D + Li → 2 He4 + energy + neutrons…
The relative abundances of the two lithium isotopes Li6 and Li7 are 7.4 % and 92.6 %, respectively. The geological resources of lithium in the earth are large enough to provide energy for several thousand years without counting the lithium in the sea water.
Lithium hypochlorite is used to clean and stop biological activity in the swimming pools or other similar facilities.
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