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Achievements in Industrial Ozone Bleaching

Pr. Emil Germer, Saint-Petersburg State Forest Technical Academy.
Alexis Métais, ITT Wedeco.
Dr. Jean-Christophe Hostachy, ITT Wedeco.

Corresponding author: Alexis.Metais@itt.com

Abstract

First industrial production of ozone bleached pulp started almost 20 years ago in connection with increasing environmental pressure and the Total Chlorine Free (TCF) wave. Like many other new technologies, ozone bleaching did not immediately reach its optimal efficiency from a technical viewpoint, but had to face several issues during its early years. By improving mixing technology, better understanding ozone chemistry on pulp components and tuning the whole process, the so-called ECF-Light bleaching sequences - including an ozone stage - made it possible to deliver a pulp quality similar or better than is produced by conventional ECF bleaching.

Today the choice of ozone may still be motivated by ecological requirements but it is mostly justified by the economical savings resulting from chemical reduction. Actually, both targets are reached simultaneously when implementing an ozone bleaching stage, whilst pulp quality is either maintained or improved.

Using results from several industrial sites, this article describes process improvements in ozone bleaching since 1992 and shows why ozone should now be considered as the keystone of modern pulp bleaching processes.

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