Purification by crystallization with a volatile refrigerant

Claim 1

THE PROCESS FOR SEPARATING DEMINERALIZED WATER FROM AN AQUEOUS SALT SOLUTION, WHICH COMPRISES COOLING SAID SOLUTION TO NEAR ITS FREEZING POINT, INTRODUCING INTO DIRECT CONTACT WITH SAID SOLUTION IN A FREEZING ZONE A LIQUID REFRIGERANT HAVING A HIGHER VAPOR PRESSURE THAN WATER, SAID FREEZING ZONE BEING MAINTAINED UNDER CONDITION SOF TEMPERATURE AND PRESSSURE WHICH PERMIT SAID REFRIGERANT TO EXPAND, VAPORIZE, AND MOVE UPWARDLY THROUGH SAID SOLUTION THEREBY FORMING ICE CRYSTALS IN SAID SOLUTION, REMOVING A CONCENTRATED SLURRY OF ICE CRYSTALS AND SALT SOLUTION FROM AN UPPER PART OF SAID FREEZING ZONE AND SEPARATING SALT SOLUTION FROM SAID ICE CRYSTALS IN A SEPARATING ZONE, SEPARATELY REMOVING A CONCENTRATED SALT SOLUTIN FROM THE LOWER PORTON OF SAID FREEZING ZONE, TRANSFERRING SAID ICE CRYSTALS TO A CONDENSING ZONE, REMOVIG REFRIGERANT VAPORS FROM SAID FREEZING ZONE, COMPRESSING REFRIGERANT VAPORS FROM SAID FREEZING ZONE, INTRODUCING RESULTING COMPRESSED REFRIGERANT VAPORS INTO HEAT EXCHANGE RELATIONSHIP WITH SAID ICE CRYSTALS IN SAID CONDENSING ZONE, WHEREIN SAID COMPRESSED REFRIGERANT VAPORS ARE LOWERED IN TEMPERATURE AND CONDENSED TO FORM LIQUID REFRIGERANT AND SAID ICE CRYSTALS ARE MELTED TO FORM WATER, AND RECOVERING WATER RESULTING FROM SAID MELTING FROM SAID CONDENSING ZONE.