Polysulfide Pulping of Southern Hardwood Employing the MOXY and Green Liquor Crystallization Processes, 1994 Pulping Conference Proceedings

J. ER Jiang, K. R. Crofut, D. B. Jones

Polysulfide (PS) pulping employing the MOXY and green liquor crystallization processes was studied in the laboratory. It was found that a lower liquor sulfidity, associated with the application of the MOXY and green liquor crystallization processes, did not appear to affect the effectiveness of PS, nor the pulp viscosity in extended modified cooking of southern hardwood. Addition of 1.5% PS was found to increase the hardwood pulp yield by about 1.2% on wood. Under the conditions studied, pulp yield increases from addition of 1.5% PS and of 0.1% AO appeared to be additive. PS pulping at the lower sulfidity did not show any significant effect on physical properties of the pulps.

These preliminary results suggest that the process of green liquor crystallization can be employed with white liquor (WL) oxidation, such as the MOXY process, for the generation of PS. This method of PS production is particularly suitable for modified cooking involving multiple WL additions.