Studies on use of oxidised white liquor in kraft pulping for prevention of digester corrosion and improvement in pulp quality

Abstract

Corrosion of process equipments was investigated by weight loss method under different polysulphide concentration. It was observed that the corrosion rate varies with polysulphide content in the cooking liquor, being higher at low concentration of polysulphide (1.5-2.5 g/l, as sulphur). At the polysulphide concentration above 19 g/l, as sulphur, it becomes constant. Under these conditions not only digester corrosion is prevented but pulp yield, having low kappa number and strength also increases in pulp yield by 2.7%, burst factor by 2.7%, breaking length by 10.1% and decrease in tear index by 1.5% as compared to kra ft pulping.