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Title
Influence of the cooking conditions on the properties of first-thinning scots pine (Pinus sylvestris) kraft pulp
Authors
Riika Rautiainen and Raimo Alen
Received
May 27, 2009
Published
Volume 43 Issue 7-8 July-August
Keywords
kraft pulping, delignification, first-thinning, pulp properties, Scots pine
Abstract
Kraft pulping of first-thinning Scots pine (Pinus sylvestris) was investigated under varying conditions to clarify the simple relationships between the principal cooking parameters (active alkali, sulfidity and cooking time) and the basic pulp properties (yield and kappa number). It was found out that, regardless of sulfidity (25 or 40%), an increase in the active alkali (25 ? 30% on wood as NaOH) resulted – for the same cooking time – in a more effective removal of lignin (of about 10%), but also in a pronounced yield loss (4- 6%). On the other hand, when aiming at the same target kappa number (of about 25), the cooking time at the maximum temperature (170 °C) could be decreased by about 35%, at the same active alkali increase.
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