Process of producing kraft pulping liquor by the oxidation of white liquor in the presence of lime mud
AssigneePulp and Paper Research Institute of Canada
InventorGilles Dorris
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Abstract
Sodium sulfide or hydrosulfide is oxidized to produce sodium polysulfide and sodium hydroxide. Under appropriate conditions, the oxidation may be pursued further to convert all the sodium sulfide into sodium thiosulfate. The oxidation is carried out at or above atmospheric pressure in a mixed reactor or in a pipeline reactor, by sparging oxygen or air, in a mixture of white liquor and lime mud particles produced in the recausticizing plant of a kraft mill.
Claims13
In a process of producing kraft cooking liquor for addition to a digester for enhancement of the yield derived from pulping of wood chips in which all the black liquor obtained from kraft digested pulp is concentrated and burned, the resulting smelt is dissolved in water to produce a kraft green liquor, causticizing the resulting kraft green liquor with lime in a causticizer to produce a kraft white liquor for use in digestion, mixed with lime mud particles whose major component is calcium carbonate, the improvement comprising the steps of:
- oxidizing the produced liquor mixed with lime mud particles in the causticizer or in a pipe line reactor directly connected to the causticizer, the liquor being oxidized consisting essentially of kraft white liquor to convert sodium sulfide in said white liquor to sodium polysulfide and sodium hydroxide,
- wherein the oxidation of said white liquor is effected by injecting small bubbles of an oxygen containing gas through a sparger into a suspension of said lime mud particles in said white liquor while agitating said suspension.
Dependencies are inferred from the claim text.