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Process of recovering sodium carbonate from spent pulping liquors

  • US 4,138,312 A
  • Filed: 05/16/1977
  • Issued: 02/06/1979
  • Est. Priority Date: 05/19/1976
  • Status: Expired due to Term
First Claim
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1. A process for the manufacture of cellulose pulp by means of a soda process in which spent liquors are concentrated by evaporation and the concentrated liquors are incinerated in a fluidized bed incinerator to produce a granular sodium carbonate incinerator product contaminated by chlorides, sulphates and potassium compounds, the incinerator product being dissolved in water and causticized in known manner to form white liquor comprising essentially sodium hydroxide, which white liquor is re-used in the said soda process to provide a closed system, the improvement comprising:

  • treating the incinerator product with water to form a slurry, agitating the slurry so as to dissolve incinerator product with its contaminants and at the same time crystallize substantially pure sodium carbonate monohydrate leaving a major proportion of the contaminants in solution, separating the substantially pure sodium carbonate from the liquor containing the contaminants, and washing the separated sodium carbonate with water;

    converting sodium carbonate remaining with the contaminants in solution to sodium bicarbonate by carbonation with carbon dioxide, separating the precipitate so formed from the mother liquor, and converting the precipitate thus recovered to substantially pure sodium carbonate;

    utilizing sodium carbonate recovered in the formation of white liquor; and

    discharging the contaminant bearing mother liquor from the system.

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