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-Ch1-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.