GB1197185A - Separation of Potassium Salts and Other Inorganic Compounds from Solutions also Containing Sodium Halide - Google Patents

Abstract

1,197,185. Separation of solid potassium chloride from brine. M. P. SWEENEY. 11 July, 1967 [11 July, 1966], No. 31049/66. Heading B1B. [Also in Division C1] Potassium chloride is separated from an aqueous solution of KC1 and NaCl by a process comprising flash evaporation of water from the solution, and' the addition to the solution of a water-miscible organic solvent such as .pyridine and/or N-methyl morpholine. In an example, a stream of hot makeup brine '(depleted of KC1) is used to dissolve KC1 from a mineral deposit comprising KCl and NaCl and the stream of return brine (rich in KC1) is concentrated by flash evaporation, the watervapour being condensed by contact with cool makeup brine. The flash evaporation causes precipitation of some of the KC1. The slurry is mixed with a solvent comprising pyridine and N-methyl morpholine, and the mixture is passed to a flash decanter where some of the solvent is vaporized, and the liquid cools with further precipitation of KC1. A concentrated slurry is removed from the base of the flash decanter, and is centrifuged to obtain the solid KC1 product. The liquid removed from the side of the flash decanter is warmed by condensation of solvent-vapour therein (see below), and then passed to a settling vessel where it separates into two liquid phases. The aqueous phase is stripped with steam to remove residual solvent, and the vapours are condensed in the liquid mixture flowing to the settler. The stripped solution is cooled by flash evaporation of water, and is recycled as makeup brine. The vapour evolved in the flash evaporation is condensed in the stream of organic phase leaving the settler, and the solvent vapours evolved from the organic phase are condensed in the stream of liquid mixture flowing to the settler. Other suitable organic solvents mentioned are the picolines, 3-methyl pyrrolidine, dimethylaminotetrahydrofuran, ethyl dimethyl amine, diethyl methyl amine, and dimethyl (2 methoxyethyl) amine. The precipitation of magnesium hydroxide from an aqueous solution is referred to.