Separation of an aqueous solution by the improved vacuum freezing high pressure ice melting process

A process of subjecting an aqueous mixture to freezing and melting operations that comprises:

• 1. a first step of simutaneously flash vaporizing and freezing an aqueous mixture derived from the feed mixture (A-solution) in a first zone (Zone-1) under a reduced pressure to thereby form a low pressure water vapor and a mass of ice;
• 2. a second step of simultaneously melting a mass of ice derived from the ice formed in Step 1 and the ice obtained in Step 3 in a second zone inside of a heat conductive conduit (Zone-2) and desublime the low pressure water vapor obtained in Step 1 in a third zone outside of the heat conductive conduit (Zone-3) to thereby simultaneously form a melt phase in the second zone and a desublimate in the third zone by
• (a) admitting the low pressure water vapor from Zone-1 to Zone-3 under a pressure lower than the triple point pressure of water, and
• (b) maintaining the ice under a sufficiently high pressure such that the melting temperature of the ice is lower than the desublimation temperature of water vapor,
• the heat released in the desublimation operation being utilized
• in the high pressure melting of ice;
• 3. a third step of simultaneously dissovling the desublimate in a dissolving solution (B-Solution) in Zone-3 and solidifying water in Zone-2 to thereby form a C-solution and ice in the two zones respectively by
• (a) pressure isolating Zone-3 from Zone-1,
• (b) bringing a quantity of the dissolving solution in contact with the desublimate in Zone-3, and
• (c) reducing the pressure in Zone-2 so that the freezing temperature in Zone-2 is higher than the dissolution temperature in Zone-3,
• the heat released in the freezing of water in Zone-2 being utilized
• in supplying the heat needed in dissolving the desublimate in Zone-3.