Drainage and fractionation of wood fibers in a flotation froth

Abstract

Understanding fiber fractionation in a froth is very important to the quality of recovered fibers in flotation deinking operations. Fiber length is a very important fiber quality parameter in paper-making. For example, long fibers tend to produce a paper with higher tear strength than short fibers. In this study, fibers in froth collected at different froth drainage times and from different heights were analyzed to obtain fiber length distributions. The length distribution of fibers in the collected froth showed a lower fraction of short fibers ( 0.8 mm) than those in the original pulp sample. The lengthweighted mean fiber length in the collected froth was 11% longer than the original TMP tested. A fiber length fractionation phenomenon was also observed along the froth vertical direction, that is, fiber collected from the upper part of a froth has a relatively lower fraction of short fibers and a longer mean fiber length than those collected in the bottom part of the froth or the original pulp. The fiber fractionation phenomenon revealed in this study indicated that flotation deinking selectively rejects more fibers greater than 2 mm compared with the original pulp sample, thus significantly impacting the quality of recovered fibers.

Citation

Zhu, J.Y.; Tan, Freya. 2005. Drainage and fractionation of wood fibers in a flotation froth. Progress in paper recycling. Vol. 14, no. 4 (Aug. 2005): p. 13-20.