METHOD FOR PROCESSING OF ALKALI SULFATE-THIOSULFATE SOLUTIONS Russian patent published in 1995 - IPC

FIELD: processing of alkali sulfate-thiosulfate solutions. SUBSTANCE: method involves treatment of origin solutions by gaseous mixture which contains hydrogen sulfide and sulfur dioxide. The process is followed by two-stepped concentration of solution and crystallization of sodium sulfate and sodium thiosulfate. Said treatment is carried out in two steps, pH of medium at the first step being 6.5-9.5, pH at the second step being 9.5-13. Method is carried out in counterflow regime of gaseous stream and solution, solution after the first step being fed for further processing. Waste gases of production of sodium sulfite are used as said gaseous mixture. EFFECT: simplifies the process, decreases cost of the process, increases yield of sodium thiosulfate. 2 cl