Recovery of Microelements

Lithium concentration in seawater does not exceed 0.17 mg/L. Nevertheless, the ocean is considered to be the most promising source of this element in the near future [107]. The overall inventory of lithium in the world s oceans is approximately 2.6x 10 tons [2]. With lithium so accessible, continual growth of lithium demand depends solely on new developments and expansion of its recovery from sea. 

Lithium is presently widely used for the production of ceramics, glass, in the aluminum industry, in ferrous metallurgy, in the chemical industry and in electrotechnics [ 108,109] Significant quantities of lithium 

Naturally occurring lithium ( 7% of Li ) needed for one solid phase blanket may vary from 5.5 to 46.8 kg/MW for one liquid blanket the need is for 1000 kg/MW [110]. 

According to predictions for the year 2000, the demand for lithium could reach 50,000-70,000 tons per year, in the Western European countries alone.This amounts to an increase by a factor of 10 from the present demand [111]. According to other estimates, the need for Li isotope in one thermonuclear reactor could be about 5000 tons per year [112]. 

The problem of lithium recovery from land-based hydromineral sources is very similar to the problem encountered in its recovery from seawater. Coprecipitation, extraction, and ion exchange, the methods used in both instances are practically the same. 

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Svanidze, A. G. Technological Schemes and Devices for Sorption Recovery of Microelements from Sea Water, Deponent VINITI USSR No. 8030-B85, Moscow, 1986. 

The world s oceans hold 1.37x10 of water (97.2% of the total amount of water of the hydrosphere). They cover 71% of the earth s surface, are actually the biggest reservoir on our planet, and contain many important minerals. The overall content of mineral matter in the oceans is estimated to be about 5 x 10 tons [1,2]. The seas contain virtually all of the naturally occurring elements and are the only universal source of mineral wealth that is available to most nations. For some of them it is the only source. Yet, most of the elements, the microelements, are available in very low concentrations, i.e., in parts per billion (ppb). The products being extracted from seawater with economic profit at present are sodium chloride, magnesium compounds, and bromine [2-4]. During the last two decades there has been growing interest in the possibility of commercial recovery of additional minerals from seawater [5] and brines [6]. 

Technical Devices for Uranium Recovery from Seawater The facilities known to exist for uranium extraction are of two types. The first type requires an external energy source. The second uses seawater motion (waves, tides, streams, etc.) as the natural source of energy. In the first type, the rate of energy expenditure per 1 ton of product (uranium or any other microelement with a concentration level in seawater of around 10 g/L) was 3x 10 kWh [229]. 

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