Pumping high-lithium brine

Sa.Ia.rs and Lakes. Brines having high lithium concentration are found in salars of northern Chile, southwestern Bohvia, and northwestern Argentina. Brines of lower lithium concentration are found in salars in the western United States and the Tibetan Plateau. Brines pumped from beneath the surface of the Salar de Atacama (Chile) and Silver Peak (Clayton Valley, Nevada) are used for commercial production of lithium uti1i2ing solar evaporation (see Chemicals frombrines). The concentration of selected ions in brines from salars and lakes of potential commercial interest worldwide are shown in Table 1. 

Recovery Process. Lithium is extracted from brine at Silver Peak Marsh, Nevada, and at the Salar de Atacama, Chile. Both processes were developed by Foote Mineral Corp. The process at Silver Peak consists of pumping shallow underground wells to solar ponds where brines are concentrated to over 5000 ppm. Lithium ion is then removed by precipitation with soda ash to form a high purity lithium carbonate [554-13-2]. At the Atacama, virgin brine with nearly 3000 ppm lithium is concentrated to near saturation in lithium chloride [7447-41 -8]. This brine is then shipped to Antofagasta, Chile where it is combined with soda ash to form lithium carbonate. 

Large lithium reserves are available in South America. A resource of special interest is the dried up salt lake Atacama, 2500 m above sea level in northern Chile. The main component is halite, rock salt, NaCl. In cavities a concentrated salt solution is present, in which the lithium content is as high as 0.15%. This solution is transported to nearby Antofagasta. In a chemical factory there the lithium carbonate is prepared from the chloride. This carbonate is an important export product. Lithium-containing brines are also available in Nevada in the USA. The brines are pumped from the ground through a series of open dams. Through solar evaporation over 12 to 18 months the brine increases its lithium concentration to about 0.6%. Soda is added and lithium carbonate precipitates. 

Brine can be pumped from the Salar s near-surface salt mass at relative high rates, such as >31.5 liter/sec (500-1000 gpm) without appreciable draw-down, although such high pumping rates would hasten the short-circuiting of brine from nearer the surface and from other areas of the Salar. The brine is saturated with salt, and contains variable concentrations of lithium, potassium, magnesium, sulfate and borate in different locations in the Salar (Tables 1.5 and 1.6 Fig. 1.12). The lithium concentration varies from about 1000-4000 ppm, and averages over 1500 ppm for the two commercial operations on the Salar. The total lithium... 

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