Carbonation of pulping liquor with subsequent partial oxidation of stripped hydrogensulfides

Claim 1

A METHOD OF PREPARING A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR USE IN THE SULFATE METHOD OF PREPARING CELLULOSE PULP, WHICH COMPRISES USING CARBON DIOXIDE FOR STRIPPING HYDROGEN SULFIDE FROM A GREEN LIQUOR CONTAINING SODIUM SULFIDE AND OBTAINED FROM SPENT LIQUOR PRODUCED IN THE SULFATE PULPING METHOD, AND THEREBY OBTAINING A STRIPPED GAS MIXTURE COMPRISING HYDROGEN SULFIDE AND CARBON DIOXIDE, PARTIALLY OXIDIZING TO ELEMENTAL SULFUR THE HYDROGEN SULFIDE IN THE STRIPPED GAS MIXTURE, USING AIR AS THW OXIDIZING AGENT, AND THEREBY FORMING A MIXTURE COMPRISING ELEMENTAL SULFUR, CARBON DIOXIDE AND HYDROGEN SULFIDE, SEPARATING THE ELEMENT SULFUR FROM THE GAS MIXTURE, TREATING THE REMAINING GAS MIXTURE WITH A CARBON DIOXIDE ABSOBENT, THEREBY REMOVING CARBON DIOXIDE FROM THE MIXTURE, AND OBTAINING A RESIDUAL GAS MIXTURE COMPRISING HYDROGEN SULFIDE AND A SMALL AMOUNT OF CARBON DIOXIDE, SEPARATING CARBON DIOXIDE FROM THE ABSORBENT, RECYCLING AT LEAST A PORTION OF SUCH CARBON DIOXIDE FOR STRIPPING HYDROGEN SULFIDE FROM THE GREEN LIQUOR, CONVERTING THE RECOVERED ELEMENTAL SULFUR TO SODIUM POLYSULFIDE, AND THEREAFTER USING THE POLYSULFIDE TO PREPARE A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR THE SULFATE PULPING METHOD.

Claim 2

A METHOD OF PREPARING A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR USE IN THE SULFATE METHOD OF PREPARING CELLULOSE PULP, WHICH COMPRISES USING CARBON DIOXIDE FOR STRIPPING HYDROGEN SULFIDE FROM A GREEN LIQUOR CONTAINING SODIUM SULFIDE AND OBTAINED FROM SPENT LIQUOR PRODUCED IN THE SULFATE PULPING METHOD, AND THEREBY OBTAINING A STRIPPED GAS MIXTURE COMPRISING HYDROGEN SULFIDE AND CARBON DIOXIDE, PARTIALLY OXIDIZING TO ELEMENTAL SULFUR THE HYDROGEN SULFIDE IN THE STRIPPED GAS MIXTURE, USING AIR AS THW OXIDIZING AGENT, AND THEREBY FORMING A MIXTURE COMPRISING ELEMENTAL SULFUR, CARBON DIOXIDE AND HYDROGEN SULFIDE, SEPARATING THE ELEMENT SULFUR FROM THE GAS MIXTURE, TREATING THE REMAINING GAS MIXTURE WITH A CARBON DIOXIDE ABSOBENT, THEREBY REMOVING CARBON DIOXIDE FROM THE MIXTURE, AND OBTAINING A RESIDUAL GAS MIXTURE COMPRISING HYDROGEN SULFIDE AND A SMALL AMOUNT OF CARBON DIOXIDE, SEPARATING CARBON DIOXIDE FROM THE ABSORBENT, RECYCLING AT LEAST A PORTION OF SUCH CARBON DIOXIDE FOR STRIPPING HYDROGEN SULFIDE FROM THE GREEN LIQUOR, CONVERTING THE RECOVERED ELEMENTAL SULFUR TO SODIUM POLYSULFIDE, AND THEREAFTER USING THE POLYSULFIDE TO PREPARE A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR THE SULFATE PULPING METHOD.