Patent ID: 6231828
Filing Date: 2001-05-15
Classification: C01B,C11D

Abstract:
A continuous process for manufacturing sodium percarbonate by reacting hydrogen peroxide and sodium carbonate in an agitated reaction vessel containing a mother liquor at a temperature from 10 to 25.degree. C. with formation of sodium percarbonate which precipitates out of solution, the precipitated sodium percarbonate being separated from the mother liquor and recovered as product the process comprising:recycling a fraction of the mother liquor separated from the sodium percarbonate and containing residual hydrogen peroxide, and continuously feeding said fraction and particulate sodium carbonate into a dissolution tank maintained within a temperature range of from 20 to 50.degree. C., wherein the dissolution tank has a sodium carbonate concentration which does not exceed 95% of a saturated solution and rate of hydrogen peroxide decomposition is retarded;continuously withdrawing a solution from the dissolution tank and introducing said solution into the reaction vessel containing an aqueous suspension of sodium percarbonate particles in the mother liquor;continuously introducing a concentrated hydrogen peroxide solution into the reaction vessel; andcontinuously introducing particulate sodium carbonate into the dissolution tank or directly into the reaction vessel or introducing a portion of the sodium carbonate into the dissolution tank and a portion into the reaction vessel, quantities of hydrogen peroxide and sodium carbonate introduced being such that, in the reaction vessel, a mole ratio calculated as H.sub.2 O.sub.2 to Na.sub.2 CO.sub.3 is maintained within a range of more than 0.7:1 and less than 1.3:1, the mother liquor being free from salting out agent, and respective flow rates of hydrogen peroxide and sodium carbonate introduced and product withdrawn from the reaction vessel being such that a concentration of sodium carbonate in the reaction vessel is maintained within a range of 100 to 160 g/kg and concentration of hydrogen peroxide in the reaction vessel is maintained in the range of 25 to 65 g/kg.