Disclosed is an improved method of separating a first salt and a second salt from an aqueous solution containing both salts and salt impurities, where the solubility of the first salt increases more with increasing temperatures than the solubility of the second salt, and at least a portion of the salt impurities precipitates as slower settling rate crystals than the settling rate of precipitated second salt. The solution is passed through a series of evaporators in which second salt and salt impurities are precipitated. The bottom of each evaporator communicates with an elutriation leg into which precipitated salts settle, and into which a fluidizing liquid is introduced to carry precipitated salt impurities back to the evaporators and from which second salt slurry is withdrawn. In the improved method, evaporator mother liquor effluent overflow having a temperature and salt composition near the temperature and salt composition of the solution in the evaporator communicating with the elutriation leg into which the fluidizing liquid is introduced is utilized as a fluidizing liquid (elutriant) in the potassium chloride recovery step.
A new process for recovery of common salt, potassium chloride, concentrated magnesium chloride with enriched bromide, and high purity magnesia from brine in an integrated manner, said process comprises preparation of calcium chloride by reaction of hydrochloric acid generated in the process with limestone, desulfatation of brine with calcium chloride, production of sodium chloride of superior quality in solar pans, solar evaporation of bittern thereby producing carnallite and end bittern, processing carnallite through established processes to produce potassium chloride, recovering end bittern containing highly concentrated magnesium chloride and enriched bromide and calcination of a part of the end bittern after solidification to produce high purity magnesia and hydrochloric acid utilizable in the process.
In a process of producing coarse pure potassium chloride crystals from feed solutions containing potassium chloride and other impurities, comprising cooling the solution under a vacuum in a plurality of stages connected in series, withdrawing by means of a conveyor the potassium chloride which has been crystallized in each stage, withdrawing the water vapors, collecting crystalline potassium chloride from the solution, drying the crystalline potassium chloride and separating the same into several fractions, compacting the fine fraction and cooling and aminating the end product, the potassium chloride content of the feed solution is increased in that potassium chloride from one or more of the stages containing solution at a low temperature is recycled to the feed solution before the latter enters the first stage. The temperature of the mixture of feed solution and recycled potassium chloride is maintained only slightly below the temperature of the feed solution, potassium chloride product is withdrawn at the desired rate from one or more of the stages which contain solution at a higher temperature, the vapors formed are withdrawn and are condensed by a direct or indirect cooling.
The invention concerns a method of preparing brine by dissolving salt in water, the salt containing sodium chloride but also calcium sulfate and/or other soluble impurities with a slower dissolution rate than sodium chloride, wherein the salt is supplied to a vessel including a grid for supporting a salt bed, water is supplied and flows through and wets at least a portion of the salt bed before it flows through the grid, whereby small solid particles form and pass through the grid whereafter they are separated from the solution, said small particles containing essentially no sodium chloride. The invention further concerns a device for making brine by dissolving salt in water, which device comprises a vessel containing a grid support, means for supplying solid salt, means for supplying water, means for the outflow of brine, and means for removing undissolved salt particles at the bottom of the vessel.
A process and apparatus for continuously removing soluble minor constituents from brines containing soluble major and minor constituents by use of a Helminthoid evaporator.
