Method of removing hydrogen sulfide from an aqueous solution of alkali sulfide

Claim 1

A METHOD FOR PREPAING A POLYSULFIDE-CONTAINING COOKING LIQUOR FOR USE IN THE SULFATE METHOD OF PREPARING CELLULOSE PULP, WHICH COMPRISES STRIPPING HYDROGEN SULFIDE FROM A GREEN LIQUOR CONTAINING SODIUM SULFIDE AND OBTAINED FROM SPENT LIQUOR PRODUCED IN THE SULFATE PULPING METHOD, BY INTRODUCING INTO THE GREEN LIQUOR A GAS CONTAINING A HIGH PROPORTION OF CARBON DIOXIDE AND LESS THAN 1% OXYGEN AND SELECTED FROM THE GROUP CONSISTING OF (A) FLUE GAS OBTAINED BY KILN CONBUSTION OF LIME MUD, AND (B) BLACK LIQUOR COMBUSTION GAS, FORMING A SOLUTION CONTAINING SODIUM CARBONATE AND SODIUM BICARBONATE, CONVERTING THE HYDROGEN SULFIDE TO SULFUR BY BURNING THE HYDROGEN SULFIDE IN THE CARBON DIOXIDE-CONTAINING STRIPPING GAS MIXTURE, SEPARATING THE ELEMENTAL SULFUR FROM THE CARBON DIOXIDE-CONTAINING COMBUSTION GAS MIXTURE AND VENTING THE CARBON DIOXIDE-CONTAINING COMBUSTION GAS MIXTURE TO THE ATMOSPHERE, CONVERTING THE SULFUR TO SODIUM POLYSULFIDES, AND USING THE SODIUM POLYSULFIDES TO PREPARE A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR THE SULFATE PULPING METHOD.

Claim 2

A METHOD FOR PREPAING A POLYSULFIDE-CONTAINING COOKING LIQUOR FOR USE IN THE SULFATE METHOD OF PREPARING CELLULOSE PULP, WHICH COMPRISES STRIPPING HYDROGEN SULFIDE FROM A GREEN LIQUOR CONTAINING SODIUM SULFIDE AND OBTAINED FROM SPENT LIQUOR PRODUCED IN THE SULFATE PULPING METHOD, BY INTRODUCING INTO THE GREEN LIQUOR A GAS CONTAINING A HIGH PROPORTION OF CARBON DIOXIDE AND LESS THAN 1% OXYGEN AND SELECTED FROM THE GROUP CONSISTING OF (A) FLUE GAS OBTAINED BY KILN CONBUSTION OF LIME MUD, AND (B) BLACK LIQUOR COMBUSTION GAS, FORMING A SOLUTION CONTAINING SODIUM CARBONATE AND SODIUM BICARBONATE, CONVERTING THE HYDROGEN SULFIDE TO SULFUR BY BURNING THE HYDROGEN SULFIDE IN THE CARBON DIOXIDE-CONTAINING STRIPPING GAS MIXTURE, SEPARATING THE ELEMENTAL SULFUR FROM THE CARBON DIOXIDE-CONTAINING COMBUSTION GAS MIXTURE AND VENTING THE CARBON DIOXIDE-CONTAINING COMBUSTION GAS MIXTURE TO THE ATMOSPHERE, CONVERTING THE SULFUR TO SODIUM POLYSULFIDES, AND USING THE SODIUM POLYSULFIDES TO PREPARE A POLYSULFIDE-CONTAINING PULPING LIQUOR FOR THE SULFATE PULPING METHOD.