Process and apparatus for preparing a potassium chloride mixture

A potassium chloride mixture with grains of different sizes is extracted in a first stage with an unsaturated solution at an elevated temperature, whereby the finest grains are completely dissolved and the coarse proportions are caused to start dissolution, the purified medium fraction is transported into a second process stage and the previously dissolved amount of KCl is crystallized there onto the purified grains at a lower temperature, forming a product of high purity with a balanced grain size and a narrow grain spectrum.