The interaction of wood and mechanical pulping equipment .1. Fibre development and generation of fines

The effects of grinding and refining on the development of pulp fibres and on the quality of the fines were studied. Seven softwood species in which fibre properties were different were selected and studied. Wood quality was defined in terms of coarseness and length of fibres in the native wood. Pulping processes used were groundwood (SGW), pressure groundwood (PGW), atmospheric refining (RMP), and thermomechanical pulping (TMP). It was found that refining makes fibres more slender and flexible than grinding because the fibre cell wall is peeled off during refining. The amount of fines generated during depends on both specific energy and wood species. Refiner fines have a greater surface than groundwood fines. The differences between the properties oi fibres-and lines produced in refining and grinding are explained on the basis of these different mechanisms.