Pilot-plant experience with ozone in TCF bleaching of eucalypt pulp

A commercial mill producing totally-chlorine-free (TCF) and elemental-chlorine-free (ECF) kraft pulp from eucalypts sought to add an ozone stage to its bleach line. TCF bleach sequences with ozone stages were tested at two pilot plants using oxygen-delignified pulp from the mill. Brightness exceeding 89% ISO was obtained with lower chemical consumption than the mill's commercial ECF and TCF pulps bleached without ozone treatment. The ozone charge and the pulp consistency during ozone bleaching greatly affect chemical consumption and product quality