TO STUDY THE EFFECT OF DIGESTER ADDITIVE ON KAPPA NUMBER, PULP YEILD & EFFLUENT LOAD IN ORIENT PAPER MILLS, AMLAI

Abstract

Two major operational problems in the pulp mills are relatively low pulp yield and high level of rejects. Conversion of some rejects into accepts can increase pulp yield without sacrificing pulp quality. To improve this conversion, the penetration and diffusion of cooking liquor into the wood chips was enhanced by adding a surface-active material to the cooking liquor. Surfactants improve strength properties by loosening of resinous materials in wood chips. This study details the effect of blend of surfactant on cooking liquor penetration and diffusion. In order to optimize the dose of digester additive designated as "DA" combined cooking is carried out with different dosage of additive for raw material mix consisting 65% bamboo & 35% mixed- hardwoods (Eucalyptus, subabool, casurina, sal & other tropical-hard woods). Bleachable grade pulp were prepared by kraft cooking of mixture of bamboo & mixed hardwoods in the ratio of 65:35 respectively. The pulps were bleached under CEPHD sequence for pulp brightness 87- 88 % P.V. and analyzed for fibre classification and physical strength properties. Characteristics of effluent at each stage of bleaching were analyzed for different parameter to examine the benefits of additive. As expected reduction in chlorine consumption due to lowering of kappa reduced shrinkage, color reversion (P.C. No.) & improve pulp viscosity and strength properties. Reduction of COD, suspended solids, dissolved solids and chloride content was observed in the effluent generated at the bleach plant.