Date of Award


Degree Name

Bachelor of Science


Paper Science and Engineering


The optimum displacement of black liquor in a Kraft pulp by a washwater can mean greater chemical recovery, reduced environmental impact, and less evaporator steam consumption. A laboratory apparatus was developed and used to test various washwaters to determine if any were more efficient at displacing the black liquor in a pad of Kraft pulp. These washwaters included tapwater, tapwater with varying amounts of a polyacrylamide polymer, and washwaters collected from various areas of a paper mill. The data generated in this project were used to calculate substance yield, dilution factor, and mobility ratio. There appeared to be no significant difference in the displacement of black liquor by any of the chosen paper mill washwaters. However, it was found that polymer additions at high concentrations significantly increased the displacement of black liquor from a pad of pulp. It was also found that increased temperature of the washwater reduced the effectiveness of the polymer solutions. Washwater, added in smaller aliquots, was more effective than if a large volume was added at one time, in displacing the black liquor.

Keywords: Washing, displacement, Kraft pulp, dilution factor, mobility ratio, channeling