METHOD OF EVAPORATION OF AQUEOUS ALKALI-SALT SOLUTIONS Russian patent published in 2003 - IPC

FIELD: chemical industry; methods of concentration of aqueous alkali-salt solutions containing sodium chloride (170-180 g/cu dm) and sodium hydroxide (120-130 g/cu dm). SUBSTANCE: aqueous alkali- salt solutions are produced in the course of chlorine diaphragm electrolysis of saturated solutions of sodium chloride which are subjected to evaporation. Crystalline waste of polyester process are proportioned into starting alkali-salt solution to be evaporated in the amount of 5-6 mg per cu dm of starting solution. Polyesters are just mixture of varying composition, %: sodium dihydrophosphate, 40-45; polyesters M-1000, 50-52 and water being the remainder. Addition of waste of polyester process reduces consumption of heating steam facilitating evaporation process and increasing sizes of common salt crystals. EFFECT: enhanced efficiency. 2 cl, 2 tbl