Ahlstrom MC Ozone Bleach Technology

Abstract

Ozone bleaching technology was developed in early 90's and introduced to mills for implementing TCF bleaching during 90's. Today ozone bleaching is used as part of ECF bleaching sequences, for instance, at UPM Kymmene Wisaforest, Finland and Modo Paper Husum, Sweden. The ozone based ECF pulp is called as ECF-light and is appreciated in Europe. In using ozone bleaching for ECF bleach sequences, it has been seen, ozone is effective to save bleaching cost and to add side-benefits of reducing pitch problems. At Wisaforest, in the ozone based ECF bleach mill, some part of bleach effluent is recovered to implement semi-closed system.Ahlstrom Machinery has developed an advanced unique ozone mixer, AMZ mixer, which is effective for selective ozone delignification, while mechanical damage to pulp is minimized. Further study on comparison between mill ozone systems with AMZ mixers and lab. ozone bleaching has indicated that mill ozone bleaching with AMZ mixer shows for better bleacheability at the same chemical charges. AMZ-MC ozone bleaching is today a fully proven technology.