Patent ID: 6162408
Filing Date: 2000-12-19
Classification: D21C

Abstract:
A process for purifying ash from a recovery boiler, the process comprising:(a) providing ash consisting of sodium sulphate and contaminants comprising chlorides and potassium salts;(b) leaching the ash in an aqueous solution at a temperature of about the boiling temperature of the aqueous solution and dissolving a portion of the sodium sulphate of the ash in the aqueous solution;(c) returning the leached ash to a black liquor to be combusted;(d) cooling the aqueous solution to a temperature that is less than about 32.degree. C.;(e) crystallizing out the portion of the sodium sulphate from the aqueous solution;(f) separating the portion of the sodium sulphate from the aqueous solution; and(g) introducing the portion of the sodium sulphate to the black liquor.