On-Line Charge Monitoring- A Wet-End Strategy, 1997 Papermakers Conference Proceedings

At the wet-end of paper machine, the interacting forces between particles and colloidally dissolved matter plays an important role to optimize runnability. While the zeta potential describes the electro-kinetic force of the fibers and fines only, the "anionic trash" is a collective term for colloidally dissolved anionic substances in a pulp furnish. It accumulates as the result of increasing water circuit closure, recycled fiber input, anionic additives in broke, and especially, as the result of a neutral papermaking process. It causes problems such as deposition and reduced performance of cationic aids. One way to decrease the amount of contraries is to outward transfer or to fix them through cationic fixing agents like alum or highly cationic polyelectrolytes. Besides the zeta potential of fines and fibers should be anionic for not destroying the sheet formation. The correlation of charge demand to paper machine parameters like breaks, retention and the built-up of agglomerates was studied.