USE OF EXHAUST GAS OF OZONE BLEACHING AND OXYGEN BLEACHING APPARATUS

PROBLEM TO BE SOLVED: To efficiently use an exhaust gas of ozone bleaching and to bleach kraft pulp by subjecting the exhaust gas of ozone bleaching to alkali scrubbing treatment to raise an oxygen concentration and using the gas as an oxygen source for oxygen bleaching. SOLUTION: An exhaust gas of ozone bleaching is subjected to alkali scrubbing treatment by an alkali scrubber 12 to remove an alkali soluble gas consisting essentially of carbon dioxide and the alkali treated exhausts gas increased in oxygen concentration is used alone or mixed with high-purity oxygen and used to utilize the exhaust gas of ozone bleaching. Preferably, an oxygen bleaching apparatus is constituted of the alkali scrubber 12 for removing the alkali soluble gas consisting essentially of carbon dioxide as an impurity in the exhaust gas of ozone bleaching, a means for adding an alkali agent to be used in the alkali scrubber 12 to a pulp slurry, a high-shear mixer 2 to mix the pulp slurry with the alkali treated exhaust gas, a means for supplying a high-purity oxygen gas to an alkali treated exhaust gas line, etc.