On the Use of Laboratory References for Predicting and Measuring the Performance of Bleach Plant Operations. Part I, 1996 International Pulp Bleaching Conference Proceedings

Bruno Marcoccia

Ahlstrom Kamyr, Inc.

Beth Sweeney

Ahlstrom Kamyr, Inc.

Randy Lowe,

Econotech Services Ltd

Bleach plant performance with respect to pulp strength was measured in six North American mills by performing fiberline audits. The audits consisted of collecting pulp samples from key stages in the fiberline and then comparing their physical properties to those of corresponding lab reference pulps. Mill brownstock and semi-bleached pulps were also bleached to final brightness in the lab so that samples collected from various stages of a fiberline could be compared to one another on a consistent, fully bleached basis. Results from the six audits are summarized and reported. It was determined that lab brownstock pulps are not suitable references: the use of lab brownstock as a reference resulted in underestimation of fiber-line performance and, in one case, obscured a significant loss of strength across one stage of the fiberline. Fiberline performance with respect to pulp strength is best measured on a fully bleached basis. For softwood market kraft pulps produced with oxygen delignification and either high or 100% chlorine dioxide substitution, the final bleached pulp strength was typically about 90% of the value of the corresponding lab reference pulps. Of the 10% difference between mill and lab pulps, between 0 and 5% was found to occur across the bleach plants.