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Decontamination of Whitewater Fines by Laboratory-Scale Flotation

Dcontamination de fines d’eau blanche par flottation en laboratoire

Dcontamination de fines d’eau blanche par flottation en laboratoire

Abstract: To our knowledge, mills have not yet developed strategies to selectively remove contaminated or aged fines from the wet end of the machine. To alleviate some of the drawbacks associated with non-selective means of cleaning whitewater, we have explored the use of dispersed air flotation. We carried out flotation tests on nine process water samples that were obtained from six different mills producing various types of paper or board. We found that laboratory flotation improved the quality of mill process water solids and increased the brightness of the handsheets made from whitewater fines by up to 2.4 units while reducing their extractives and ink content by up to 59% and 48%, respectively. Flotation selectively removed the smallest and most contaminated solids from paper machine waters. Decontamination of whitewater by flotation may lead to improved sheet properties, reduction in the use of papermaking and bleaching chemicals, improved paper machine runnability, and increased water system closure.

Paper presented at 94th PAPTAC Annual Meeting in Montreal, February 5-7, 2008

Full manuscript available at www.paptac.ca.