SODA PULPING OF SAPWOOD

Abstract

Pulping of sapwood by soda and soda-anthraquinone (AQ) processes was done with varying cooking variables, namely cooking time, temperature, alkali concentration and liquor ratio. At 20% alkali concentration in 2 hours of cooking at 170 °C, sapwood produced pulp of about 42% yield with kappa number of about 25. The pulp yield was increased by 2—3% on ovendried (o.d.) wood with an addition of 0.1% AQ in soda liquor at the targeted kappa number of 25. The addition of AQ in soda liquor saved cooking time by 1 hour or alkali concentration by 2% on o.d. wood. The physical properties of sapwood pulp from soda-AQ process were greater than those of pulp from soda process.