Every given pulp source in the pulp and paper industry contains a certain amount of so called fines defined as the fraction passing through a mesh with an opening diameter of 76 µm. The amount depends on the pulping process (mechanical/chemical) and on subsequent mechanical treatment (accounting for secondary fines) in stock preparation and can range up to a mass ratio of 25%. Their morphological, chemical and technological properties differ distinctly from the corresponding fibre fraction and making use of these differences can be a way to gain added value from the given source. In the past, several researchers have already proposed approaches to enhance properties of the final product or the production process itself by especially dealing with fines fractions. A prerequisite to address this topic is a convenient method to separate the fines fraction from the source and comprehensive morphological, chemical and technological characterisation of these fines.<br/>In this work we present a continuous method to separate the fines fraction from the fibres in the laboratory scale to produce amounts up to 100 g of pure fines material with reasonable effort. We will discuss statistically significant morphological characterisation based on a flow cell and microscope imaging and some exemplary results on fines from different sources. We will also discuss differences in chemical composition compared to the fibre fraction and the implied impact on the pulping and bleaching process. For reliable evaluation of the impact of these fines in papermaking products a method providing sheets with defined fines content is needed. Such a method will be presented together with exemplary results on the technological properties of different fines from different sources. Finally some possible applications in the pulp and paper industry will be outlined based on the presented results.

Characterisation of pulp fibre fines and their technological properties

251st National Meeting (2016)

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