METHOD OF BLEACHING HARDWOOD PULP AT STAGE (D) IN PRESENCE OF Mg(OH) Russian patent published in 2012 - IPC D21C9/14 

FIELD: chemistry.

SUBSTANCE: present invention relates to an improved method of bleaching cellulose, involving at least one bleaching stage which involves treatment of hardwood pulp with a bleaching agent containing ClO₂, in the presence of a weak base, for example Mg(OH)₂, preferably at pH from 3.5 to 6.5 and at temperature from 55°C to 85°C. Cellulose consistency ranges from 10% to 20% and curing time ranges from 10 minutes to 300 minutes. The invention also relates to a method of bleaching cellulose, having two or more bleaching stages, at least one, preferably two, of which involve treatment of cellulose with a bleaching agent containing ClO₂, in the presence of a weak base, for example Mg(OH)₂, preferably at pH from 3.5 to 6.5.

EFFECT: invention increases efficiency of bleaching cellulose, reduces expenses on bleaching, increases purity of cellulose and enables to obtain cellulose with high and stable brightness.

9 cl, 5 ex, 6 tbl, 7 dwg