Lithium has worldwide been proven of great energetic interest. One of the origins of lithium is salt lakes brine. Tunisia is marked by the presence of many saline systems containing lithium ranging from 20 mg/L to 50 mg/L. Nonetheless, extracting lithium from natural brine is really finding a needle in a haystack. This difficulty is basically due to the nuclear, electronic, and thermodynamic features of lithium as well as the other ions present in the brine. In this chapter, the authors study the technical and thermodynamic methods leading to the enrichment of lithium in brine, which in turn leads to its easy extraction. For this reason, techniques of extraction and their limitation were reviewed. In addition, the evaporation process of the brine is thermodynamic methods leading to an enrichment of with lithium in the brine due to the extraction of water molecules. Also, the precipitation of minerals including ions representing a noise of the lithium, especially magnesium, paves the way for easy extraction within lithium window.
TopIntroduction
Alkali metals are also called the lithium family (Quintero et al., 2021). Like other alkali metals sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), lithium has a single valence electron which is easily yielded to form a cation. For this reason, lithium is a good conductor of heat (Wong et al., 2022) and electricity (Anokhina et al., 2021) as well as a highly reactive element (Park et al., 2021), although it is the least reactive of the alkali metals. The low reactivity of lithium is due to the proximity of its valence electron to its nucleus (the two remaining electrons are in the 1s orbital, much less energetic and do not participate in chemical bonds). Molten lithium is significantly more reactive than its solid form (Harvey et al, 2021).
Lithium metal is soft enough to be cut with a knife. When cut, it has a silvery white color that quickly turns gray when oxidized to lithium oxide. Its melting point of 180.50 °C (453.65 K; 356.90 °F) and its boiling point of 1342 °C (1615 K; 2448 °F) which is the highest of all the alkali metals while its specific gravity of 0.534 is the lowest.
Lithium has a very low density (0.534 g / cm3), comparable to pine wood. It is the least dense of all solid elements at room temperature; the next lightest solid element (potassium, at 0.862 g / cm3) is 60% denser. Aside from helium and hydrogen, as a solid it is less dense than any other element in liquid form, being only two-thirds as dense as liquid nitrogen (0.808 g / cm3). Lithium can float on the lightest hydrocarbons and is one of only three metals that can float on water, the other two being sodium and potassium.
The coefficient of thermal expansion of lithium is twice that of aluminum and almost four times that of iron. Lithium is superconducting below 400 μK at standard pressure and at higher temperatures (over 9 K) at very high pressures (> 20 GPa). At temperatures below 70 K, lithium, like sodium, undergoes phase change transformations without diffusion. At 4.2K, it has a rhombohedral crystal system (with a repeat spacing of nine layers); at higher temperatures, it changes to face-centered cubic and then to body-centered cubic. At liquid helium temperatures (4K), the rhombohedral structure is predominant; multiple allotropic forms have been identified for lithium at high pressure.
Lithium has a specific heat capacity of 3.58 kilojoules per kilogram-kelvin, the highest of all solids. For this reason, lithium metal is often used in coolants for heat transfer applications. These physicochemical properties create analytical difficulties for the analysis and extraction of lithium. In this chapter, we are really going to analyze and extract lithium is really looking for a needle in a haystack.
TopGlobal Lithium Resources Estimation And Fields Of Application
Recently, the United States Geological Survey (USGS, 2021) estimated lithium resources at about 80 Million Tons (MT) distributed on 23 countries (12 major owners and 11 minor owners). Resources of major owners (Fig.2a) like Bolivia and USA are above 1 MT. On the other hand, resources of minor owners (Fig.2b) such as Peru and Spain are less than 1 MT. As a matter of fact, the production of lithium is not proportional to the existing reserves. Instead, other parameters including difficulty of extraction process make major owners not located in the production record.
Figure 2. Lithium resources (Mt) and major countries distribution