MEDIUM-CONSISTENCY BLEACHING WITH HIGH-CONCENTRATION OZONE GAS IN THEPAPRICAN PILOT-PLANT AND A COMPARISON WITH LABORATORY BLEACHING .2. OZONE BLEACHING RESULTS - THIS PART PRESENTS EXPERIMENTAL DETAILS AND ADISCUSSION

The initial operation of the medium-consistency pilot plant at Paprica n has shown that variation in results can be minimized by ensuring a c lean gas injector surface and decreasing air entrainment in the feed p ulp. A good correlation has been found between the amount of carbon di oxide and carbon monoxide formed by reaction of ozone with the pulp an d the decrease in Kappa number. A comparison with laboratory bleaching showed the variability in the pilot plant operation was higher. Compa ring medium- and high-consistency bleaching in the laboratory also sho wed that the efficiency of ozone use declined at medium consistency wi th charges above 0.5% ozone on o.d. pulp.