The study results have showed that peroxide-alkaline
delignification and bleaching by sodium chlorite
(instead of chlorine dioxide) is more appropriate for
bleaching sulfate hardwood pulp. ECF bleaching of
hardwood pulp according to the scheme Pa-E-Ch 1-Ch2-
OxA with a degree of penetration 94 Pep.u. results in
pulp whiteness - 88.9% with a very low pitch
concentration with insignificant decrease in mechanical
strength.
The proposed scheme of hardwood pulp bleaching
simplifies the bleaching technology by exclusion of EPO
under pressure and avoiding of additional construction of
facilities for production of chlorine dioxide using sodium
chlorate.