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chloride is maintained only slightly below the temperature of the feed solution, potassium chloride product is withdrawn at the desired rate from one or more of the stages which contain solution at a higher temperature, the vapors formed are withdrawn and are condensed by a direct or indirect cooling.