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You are here : Home > Training > EFPG Days > 8- Ozonisation of high kappa pulps (slides 1-8)

Last update : August 12, 2003

			Second Session : The Yield Issue
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					VIII - Ozonation of high kappa pulps New possibilities (slides 1-8) Dinah Nyangiro (EFPG)

	1 - State of the art   Environmental protection legislation: levels of bleaching process waters containing suspended solids, dissolved organic matter and AOX   Process economy: water, wood and reagent consumption, effluent treatment   Oxygen delignification industrial practice: increase selectivity, yield, reduced AOX and reagent costs   Ozone is a powerful oxidant with no AOX production: possible alternative to oxygen delignification   Use of ozone to substitute chlorine dioxide has proved very promising: reduction of chlorine dioxide load				2 - Objective DEVISE NEW METHODS OF OZONE APPLICATION TO INCREASE OZONATION SELECTIVITY

	3 - Oxygen delignification   Oxygen delignification upstream before bleach plant is a common industrial practice   OO- delignification stage significantly reduces the boiler load, as wood consumption for constant bleached pulp production is reduced   AOX level (directly proportional to KN of pulp going into the bleach plant) reduces as the kappa number into bleach plant is lower				4 - Conventional kraft pulping yield Screened yield on wood for kraft pulping process, as a function of kappa number. For kappa numbers less than 30 KN, yield loss or shrinkage was 0.27% per unit kappa drop (yield - kappa line gradient). Data from: Homer 96/PPT

	5 - Pulping with conventional bleaching Screened yield on wood as a function of kappa number for pulping with conventional bleaching. Data from: Homer 1996/PPT				6 - Pulping with oxygen delignification Screened yield on wood as a function of kappa number for pulping with oxygen delignification. High KN of 40 to 50 instead of the conventional 30 KN, followed by an oxygen delignification: up to 2% pulp yield increase. Data from: Homer 1996/PPT

	7 - Ozonation conditions      HC ozonation, 20°C at pH 2, kraft softwood (Norwegian spruce)   2% (on OD pulp) ozone charge at 70 g/m3 concentration   kraft pulp at 52 kappa number				8 - Ozone delignification Comparison of ozone treated pulp yields (for 60 and 27 KN pulps) with kraft pulping process yield. Variation of overall yield with kappa number.

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