Process for solar concentration of lithium chloride brine

Abstract

By evaporation employing solar energy, a brine having a lithium chloride concentration greater than that of a brine whose vapor pressure under ambient conditions is substantially equal to the partial pressure of moisture in the atmosphere above the brine is obtained. The process by which such result is accomplished involves the use of a pond system consisting of a series of shallow ponds of relatively large surface area to which a dilute lithium chloride brine is introduced. The flow of the brine through the pond system is controlled so that, at a point intermediate the points of introduction of the brine to and withdrawal of the brine from the pond system, the concentration of the brine is such that its vapor pressure under ambient conditions is substantially equal to the partial pressure of the moisture in the atmosphere immediately above the pond system. This more concentrated brine is then caused to flow through the remainder of the pond system at a rate such that the temperature thereof, as a result of exposure to solar energy, exceeds that of the atmosphere above the pond system whereby additional water is evaporated from the brine to further increase the lithium chloride concentration of the brine. The concentrated lithium chloride brine is recovered and may be used to generate impure lithium chloride monohydrate or further purified to provide relatively pure anhydrous lithium chloride or the monohydrate.