Pulping and bleaching OCC. Part Ⅱ. Oxygen delignification and bleaching

摘要

The course of oxygen delignification of pulps obtained from two kinds of OCC waste paper was studied. The susceptibility of these pulps to ECF and TCF bleaching processes was also compared with that of birch and pine kraft pulp. The final yield and the intrinsic viscosity of bleached pulps produced from OCC waste paper were determined and compared with the properties of pulps produced from birch and pine. The results showed that the susceptibility of OCC pulps produced from unprinted OCC to oxygen delignification and bleaching is good. The most important problem related to processing OCC into bleached pulps seems to be the cleaning of these pulps of coloured particles that give the pulps a grey colour. The study showed that the place (stage), as well as the method of removing these particles from OCC pulps may have a significant influence on the effectiveness of this process and the final yield of bleached OCC pulps.