# Lithium Concentrations in Saline Brines of the Shu-Sarysu Depression
## 1 Introduction  
According to experts in the field, there is a projected threefold increase in the demand for lithium by the year 2028, with an estimated annual consumption ranging from 550,000 to 600,000 tons [1]. Furthermore, there has been a substantial surge in the price of lithium carbonate between 2021 and 2022, soaring from USD 55,000 to USD 327,500 [2]. Various experts, as referenced in sources [3, 4], estimate the global lithium resources at a staggering 13 million tons, while the current global consumption stands at 65,000 tons annually. It is worth noting that 22% of the confirmed lithium resources are concentrated in pegmatite deposits, while the remaining 78% can be found in continental brine sources [1]. At present, the primary lithium producers are located in Latin American countries, Australia, and China [1, 2, 3, 4]. In Australia, the primary source of lithium comes from pegmatites, whereas in Latin American countries and China, lithium production relies on the exploitation of hydro-mineral resources (Salar de Atacama, Chile; Salar de Uyuni, Bolivia; Salar del Hombre Muerto, Argentina; a series of salt flats in the Qinghai-Tibet Plateau, China) [2, 3, 4, 5, 6]. An examination of the factors influencing the formation of salt flats in South America, Tibet, and Mongolia yields the following conclusion: the Li\({}_{2}\)O content within the waters of the final runoff reservoirs is governed by several factors, including the lithium content in the groundwater and subterranean waters, the level of brine mineralization, the tectonic and volcanic activity within these regions, as well as the prevailing climatic conditions. These combined factors can result in the repeated precipitation of highly soluble salts, ultimately leading to the enrichment of brine with lithium. Furthermore, the depressionsof tectonic origin that encompass the salt flats, along with their associated drainage basins, serve as natural geomorphological and structural traps where the accumulation of easily mobile and soluble components, such as lithium, takes place [4]. The findings from saline brine deposits highlight the importance of conducting exploration for critical elements, including lithium, in Kazakhstan. First of all, the Caspian basin, in which salt deposits have long been exploited for the extraction of halite, sylvive, gypsum, boron, and magnesite, is favorable for the exploration of lithium brine deposits in Kazakhstan. Saline brine deposits of this nature are extensively found in the region, including the desiccating Aral Sea, the Shu-Sarysu salt flats, and potentially the salt lakes in the Ertis River region. Nevertheless, the extraction of valuable components from Kazakhstan's salt flats has remained at a rudimentary stage, despite the fact that mineralized waters in many cases contain a diverse array of components [7]. Lithium is extracted from three types of deposits: \"hard-rock\" pegmatites, continental brines in \"salars\", and hydrothermally altered clays. Brine deposits account for around 75% of the world's lithium, due to lower costs of extraction [2; 3; 4; 5]. Li-rich brines are found predominantly in basins of internal drainage or salars which are mainly located in the Andes in the Lithium Triangle countries. They are endorheic basins, meaning that the only exit for the inflowing water is via evaporation. This means that water, rich in lithium, flows to the salars and is then evaporated, resulting in the deposition of minerals. Over long time periods (-Ma), high-density brines collect in a nucleus that contains economic concentrations of lithium which is then pumped out. Whilst extraction from rocks requires a hydrometallurgical process (crushing and heating), extraction from brines, i.e., saline aquifers, involves the pumping from the shallow subsurface and a set of solar evaporation ponds where the liquid solution is moved from one to another until a desired concentration, or \"purity\", is reached.