Processing calcium and magnesium carbonate slurry - from sulphite spent liquor utilisation by treatment with sulphur dioxide

摘要

Processing of carbonate slurries, esp. with Ca or Mg as base, from the ultilisation of sulphite spent liquors, comprises treatment of the slurry, in aq. suspension with 5-30% solid content, which gaseous SO2 and then using the soln. immediately and directly as liquor for the decompsn. of wood or adding to liquor already present. The process pref. is used in a base circulating system in the recovery of cellulose, SO2 being passed into the carbonate slurry on one side of the cycle and refined Na lignosulphonate spent liquor recovered on the other side. The carbonate slurry can be utilised without environmental pollution and with min. energy consumption. The Na lignosulphonate formed can be used as dispersant, e.g. in the prodn. of plant protective agents and dyes.