Fines from different pulps compared by image analysis

The study comprised methods for the analysis of the fines content and type, and the interrelations between different methods. An image analysing method was adopted for studies on different pulps. For TMP and chemical pulps image analysis correlated relatively well with results from the more tedious specific sedimentation Volume (SSV) method. Fines variations in mills are illustrated in some case studies. In TMP screening, accepts contained a higher percentage of fines than the corresponding feed and reject flows. In addition, the fibril content of the fines fractions changed during screening, so that fines in accepts were less fibrilla than the corresponding reject fines. In a GW process there was less variation in screening accepts. Therefore there seem to be fewer possibilities to control the fines and fibril contents in the outgoing GW pulp by combining screening accepts. For chemical pulps an increase in the fibril content is a measure of the generation of secondary fines. Monitoring fines in the process is probably a step towards better process and pulp performance control.