A method of adding alkali to the pulp to provide high-purity oxygen delignification

摘要

The present invention relates to an oxygen delignification method for treating wood pulp to yield a solid tallignified pulp.;The decolorized pulp 8 is mixed with the aqueous alkaline solution 10, 14A in a low-stiffness state so that the alkaline material can be distributed substantially uniformly throughout the pulp. Thereafter, the viscosity of the pump is increased to about 15% or more, and the pulp containing the alkali having high viscosity is treated with oxygen (21) to be delignified (20). The total amount of alkaline material applied to the pulp is from 0.8 to 7% by weight, based on the weight of the oven dried pulp. As a result, high-strength, low-lignin pulp is formed and bleached with high lightness with a reduced amount of compound.