METHOD OF BLEACHING SULPHATE PULP Russian patent published in 2012 - IPC D21C9/10 

FIELD: textiles, paper.

SUBSTANCE: method of bleaching sulphate pulp involves stages of delignification and afterbleaching in two stages with sodium chlorite with intermediate alkaline extraction in the presence of hydrogen peroxide. Delignification is carried out with hydrogen peroxide in an acidic medium in the presence of sodium molybdate catalyst at a rate of 1.0-5.0% H₂O₂, H₂SO₄ 1.0%, 0.5% of Na₂MoO₄ by weight of absolutely dry pulp at a temperature of 75-95°C for 120 -150 min and the mass concentration of 10%. Then alkaline treatment is carried out at a rate of NaOH 1.5% by weight of absolutely dry pulp at a temperature of 60-70°C for 60-90 min.

EFFECT: method increases ecological way of the process of bleaching.

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