Lithium salts have found utility in various applications. For example, lithium nitrate is known for use in ceramics, pyrotechnics, salt baths, heat exchange media, refrigeration systems, rocket propellants and specialized concrete applications. Another useful lithium salt, lithium bromide, is known for use in pharmaceuticals, air conditioning systems, low temperature heat exchange media, drying agent, refrigeration systems, batteries, medicine and as a humectant.
The conventional method of producing many lithium salts is to combine either lithium carbonate or lithium hydroxide with acids containing the desired anion for the lithium salt. For example, the conventional method of producing lithium nitrate is to react lithium carbonate and/or lithium hydroxide with nitric acid. Nevertheless, this process requires high purity raw materials and very expensive plant equipment and metal of construction for the handling of the highly alkaline lithium salts and concentrated nitric acid.
Similarly, the conventional method of producing lithium bromide is to react hydrobromic acid with lithium hydroxide or lithium carbonate. The saturated solution on cooling precipitates lithium bromide monohydrate, which can be dried to the anhydrous salt. Nevertheless, hydrobromic acid is a very irritating colorless gas that fumes strongly in moist air. Furthermore, hydrobromic acid is classified under DOT regulations, as highly corrosive, and, highly irritative to eyes, skin and respiratory passages. Therefore, the production of lithium bromide using hydrobromic acid can be quite dangerous.
As described above, the use of highly acidic materials in the formation of lithium salts is undesirable as the materials are generally hazardous and require special equipment. Furthermore, the above processes generally do not produce high yields of the lithium salts being produced and therefore cannot be used where high purity lithium salts are desired. Therefore, there is a need to provide an inexpensive method of increasing the purity of the lithium salts without using highly acidic materials.
USPTO Backgrounds
USPTO Backgrounds