METHOD OF PROCESSING ALKALINE SULFATE-THIOSULFATE SOLUTION Russian patent published in 1995 - IPC

FIELD: chemical technology. SUBSTANCE: method involves sulfuric acid treatment of alkaline sulfate-thiosulfate solutions followed by their two-stage concentration and sodium sulfate separation at the every stage. After the second stage sodium sulfate is recovered to the head process, and mother liquid is fed to the crystallization of sodium thiosulfate. Sulfuric acid treatment of the parental solution is carried out by addition of sulfuric acid at the average rate 1-2.2 l H₂SO₄/kg NaOH x h, preferably at 1.3-1.7 up to the final pH value in the medium 6.5-8.5. Concentration of neutralized solution at the first stage is carried out up to the content of sodium thiosulfate 12.5-14.5, preferably 13-14. EFFECT: simplified process, improved labor conditions. 2 cl