Abstract: Disclosed is a method of reducing the sodium chloride content of potassium chloride by forming an aqueous slurry of potassium chloride feed crystals having a wide particle size distribution with an average diameter of about 0.1 to about 50 microns in a liquor saturated with potassium chloride and undersaturated with sodium chloride, which is at least 50% saturated with sodium chloride, whereby the smaller of the feed crystals dissolve and potassium chloride grows on the larger of the feed crystals to form product crystals removing the product crystals from the slurry. Also disclosed is an apparatus for carrying out this process.

Abstract: A method of operating a plurality of electrolytic diaphragm cells utilizing interruptable or off-peak electrical power varying from a higher electrical load level to a lesser electrical load level and subsequently returning to a selected higher electrical load level is described, which comprises the steps of:(a) reducing the brine feed into each cell in an amount at least about proportional to the scheduled electrical load reduction,(b) reducing the electrical load from a higher level to a lower level over a time period of not less than about 20 minutes,(c) operating the cells at such lower electrical load level until additional current is available, and, when additional current is available,(d) increasing the brine feed into each cell to between about 100 and about 150 percent of the original feed rate,(e) increasing the electrical load level to a selected higher level over a period of not less than about 10 minutes,(f) adjusting the brine feed to the original feed rate, and(g) maintaining the caustic concen