Abstract: An improved freeze concentration system of the type in which a slurry of crystals and mother liquor are formed in a crystallizer and fed to the concentrated end of a gradient column. The crystals grow in size in the column as they move to the dilute end of the column. The dilute slurry is transferred to a holding tank where the crystals grow further and then to a wash column. A slurry of larger crystals from the holding tank or the column outlet are fed back to the column inlet so that crystals in the concentrated slurry dissolve and reform on the large crystals of the fed back slurry. The units can be connected in a multistage, counter-current system.