DefinePK

Abstract

ABSTRACT The laboratory studies of wood and pulping properties of chir pine trees of different age groups were described in the earlier articles in this series. These studies indicated the superiority of 36-45 year old trees for pulp manufacture. Therefore, 200 trees of this age were procured for pilot scale pulping and paper making tests. Approximately 41.5 tons of chir pine wood in green condition was chipped on multiple knife chippers with 0.7, 1.5, 95.0 and 2.8% production of knots, oversize, acceptable chips and fines respectively. Energy consumption was found to be 9.75 kWh per ton of green wood. Three digesters, each containing 6 tons of wood on oven dry weight basis were cooked. Average screened pulp yield was found to be 46.3%with a Kappa number of 25. After washing and screening, three stages bleaching of pulp was carried out by chlorination, alkali extraction and hypochlorite bleach. Facilities for the fourth stage were not available and therefore, a low pulp brightness of 750 GE was attained. The bleached supphate pulp was evaluated in the form of mixed furnish for the manufacture of different grades of paper and paperboard and its quality was compared with imported long fibre pulp used for the same purpose. The strength properties of paper and board containing chir pine pulp in the mixed furnish was comparable to that which had imported long fiber pulp. However, folding endurance and breaking length were lower in the former than the latter.