Laboratory strength results of DZ bleaching on a variety of pulps

Production of ECF bleached pulps utilizing ozone, chlorine dioxide, oxygen and hydrogen peroxide is gaining acceptance as a cost effective and highly flexible method to produce excellent quality pulps with minimal environmental impact. This paper examines the most recent developments in Ozone-ECF bleaching from the standpoint of bleach chemistry, process implementation and effluent characteristics. Emphasis is placed on the development of ozone application techniques, the strength of laboratory bleach sequences and modeling of full scale mill costs. Ozone bleaching has not always delivered adequate strength results when applied as a full Z stage in both TCF or ECF bleaching. ECF bleaching sequences of(ZD/DZ) Eop D E D has consistently delivered equal if not better strength results than D-0. This paper will review our lab findings on a variety of pulps.