Nihon Cellulose Co., Ltd.

Kabushiki Kaisha Toa Kogyo

K.i. System Co., Ltd.

Akira Ako

Sadao Kitagawa

Kazumasa Koike

A pulp production process can produce pulp at high yield without using sodium sulfide and high-temperature/high-pressure conditions if compared with the Kraft process and also collect lignin. Pulp is produced by processing wood chips for hydrophlicization at room temperature, using a dilute caustic soda aqueous solution, selectively partially modifying lignin in dilute nitric acid and digesting the wood chips by means of a dilute caustic soda aqueous solution under the atmospheric pressure. Lignin is agglomerated and sorted out from the isolated black liquor.

Method for production of pulp

Lignin and alkali are efficiently sorted out of alkaline black liquor discharged from the paper manufacturing/pulp and paper manufacturing industries and the treated water is made as purified water. Acid is added to the black liquor and its pH is adjusted to 2.5 to 3.5. An aggregating agent is added to have lignin contained in the black liquor settled and the black liquor is separated into lignin and clean water. Ozone gas, preferably in the micro bubble state, is given to the clean water for contact reaction.

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Yokosuka, Japan

Akira Ako