Process for monosulfite recovery

Claim 1

THE METHOD OF CONVERTING SODIUM SULFIDE, TOGETHER WITH ANY SODIUM CARBONATE PRESENT IN SMELT LIQUOR OBTAINED FROM THE PULPING OF WOOD, TO SODIUM SULFITE, WHICH COMPRISES PASSING A STREAM OF CO2 IN INTIMATE CONTACT WITH SAID LOQUOR OF CARBONATE SAME WITH THE FORMATION OF SODIUM SALTS OF CARBONIC ACID AND H2S AND SIMULTANEOUSLY TO STRIP FROM SAID LIQUOR SAID H2S, THE QUANTITY OF CO2 UTILIZED BEING SUBSTANTIAL EXCESS OF THE STOICHIOMETRIC AMOUNT FOR CARBONATING SAID LIQUOR TO EFFECT A SUBSTANTIALLY COMPLETE STRIPPING OF SAID H2S FROM SAID LIQUOR BY CO2 SWEEPING, PASSING THE H2S-BEARING STREAM OF CO2 TO AN OXIDIZING ZONE WHEREIN SAID STREAM IS BROUGHT INTO CONTACT WITH SO2 WHEREBY TO OXIDIZE SAID H2S TO ELEMENTAL SULPHUR, REMOVING SAID SULPHUR FROM AND STREAM, ENRICHING SAID STREAM OF CO2 WITH SO2, AND UTILIZING SAID SO2-ENRICHED STREAM TO SULFITE THE ALREADY CARBONATED SMELT LIQUOR TO CONVERT THE CARBONATES PRESENT TO SULFITES AND TO OBTAIN SUBSTANTIALLY PURE CO2.