The Effects of APMP Process Variables on Aspen Pulp Yields and Properties, 2007 International Mechanical Pulping Conference

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It is well known that to produce mechanical pulp from hardwood shaving reasonable strength properties, some kind of alkali pretreatment before refining is necessary (CCS, CTMP or APMP). It has been shown clearly that APMP is a better process than the others interm of overall pulp property development, process consumption, yield and other process costs. In addition, APMP is demonstrated to be a very flexible process in which pulp yield and properties can be changed easily by varying the process conditions. Int his paper an attempt was made to investigate the effects of some process variables on APMP pulp yield and properties of two poplar species from Iran: P. alba and P. nigra and their different blend ratios. Two stage impregnation was used and the process conditions have been varied in away to make a balance between hydrolysis and brightening reactions with the aim to produce APMP pulp with target bightness of about 80% and pulp yield ranges of 86 to 89%. Total chemicals used in the pretreatment varied: sodium hydroxide being 67% and hydrogen peroxide being 56% with usage ratios of 40, 50 and 60%, and 20 to 40% of total charge in the first impregnation stage, respectively (all based on OD chips), plus fixed amounts of peroxide stabilizer chemicals.