Sulfate pulping process by mixing soft wood with hard wood

Abstract

The invention discloses a sulfate pulping process by mixing soft wood with hard wood. The process comprises the following steps: preparing materials; steam-cooking by a sulfate process; washing and screening; and bleaching. The process is characterized in that soft wood and hard wood chips are evenly mixed based on the weight ratio of (7-8): (2-3), and then are transferred to a digester for steam-cooking and pulping by the sulfate process. In the process, mixed steam cooking is carried out on the soft wood and the hard wood by a vertical digester without equipment remodeling, and other process flows are basically same as those for producing masson pine sulfate soft wood pulp, thus widening adaptability of a steam-cooking system to raw materials, and relieving pressure of the wood fiber raw materials; and compared with the masson pine pulp, the quality of the wood pulp obtained through mixed steam-cooking is not obviously lowered under the condition that the proportion of poplar wood does not exceed 30%.

Description

technical field [0001] The invention relates to a kraft mixed cooking pulping process, in particular to a mixed pulping process of coniferous wood and broad-leaved wood. Background technique [0002] The paper industry is an important basic raw material industry closely related to the development of the national economy and social undertakings. The consumption level of paper and cardboard is a symbol to measure the level of modernization and civilization of a country. [0003] my country is a country with serious shortage of timber resources. Since virgin wood pulp is significantly better than non-wood fiber in terms of water filtration performance and tear strength, China needs to consume a large amount of wood pulp fiber every year. In 2009, wood pulp consumption reached 18.66 million tons, of which imported wood pulp reached 13.15 million tons. Therefore, how to improve the self-sufficiency rate of wood pulp and reduce the dependence on imported wood pulp is a major...

AI Technical Summary

Problems solved by technology

Since the lignin content of poplar is generally about 22%, while that of masson pine is about 29%, and the fiber length of poplar is shorter than that of masson pine, the average length of poplar fiber is 0.86mm, and that of masson pine is 3.61mm. There are too many differences, so the two raw materials are mixed and cooked. If the conditions are not controlled properly, the poplar wood will be over-cooked and the masson pine will be under-cooked.