IMPORTANCE OF THE HARDWOOD CHIPS QUALITY FOR PULP PRODUCTION

The aim of this work was to underline the importance of hardwood chips quality for pulp production under the conditions of modern displacement sulphate cooking. The speed at which the cooking chemicals come into contact with particular wooden fibres is decisive for the optimal delignification process. This speed is given by chips quality - their dimensional, chemical and moisture uniformity. Quality of the hardwood chips was evaluated by gravimetric method (amount of impregnated liquor, yeld and content of undercook) and by chemical methods (residual effective alkali content and Kappa number). The recommendations are summarized and based on obtained knowledge of optimal delignification process of non-uniform hardwood chips: recommended thickness of well-impregnating and cooking sapwood chips is 3-4mm, recommended thickness of hardly impregnated and cooked heartwood is 2-3mm, constant ratio of sapwood and heartwood mixture (the recommended ratio is 4: 1), the maintenance of constant and high moisture of the chips entering into cooking replacement. The suitable combination of parameters stated above allows the production of high quality pulp from non-uniform chips.