Improved Deresination Agents: Laboratory and Mill Results, 1997 Pulping Conference Proceedings

Surfactants are used in some pulp mills to reduce resin content, particularly in sulfite pulping mills for pulps destined for conversion to synthetic fibers such as rayon. In some alkaline pulping mills, alcohol ethoxylates are used as pitch control agents. (Due to environmental concerns, some mills have switched from alkylphenol ethoxylates to alcohol ethoxylates for these applications. Our objective was to determine the effectiveness of alcohol ethoxylates and alcohol ethoxylate-containing formulations in deresination applications.

Laboratory results indicate that, when in comparing an alcohol ethoxylate and a nonylphenol ethoxylate used commercially for deresination, the alcohol ethoxylate provided lower interfacial tension and increased laboratory deresination efficiency.

A proprietary alcohol ethoxylate was then tested and adopted for commercial use in two North American mills manufacturing high grade dissolving pulp. Detailed months-long testing in one mill indicated the finished pulp resin content did not change when the mill switched to the alcohol ethoxylate from a nonylphenol ethoxylate. Compared to the nonylphenol ethoxylate, the alcohol ethoxylate surfactant provided the following operating benefits:

· substantially lower levels of residual surfactant in mill effluents

· less foaming was observed in the secondary clarifier when using the alcohol ethoxylate resulting in lower defoamer consumption

· lower solids carryover from both the anaerobic and aerobic water clarification units

· increased methane production from the anaerobic water clarification unit