Mo Och Domsjo Aktiebolag

Mooch Domsjo Ab

Lars G Rudstrom

Jonas A Lindahl

A process is provided for the manufacture of bleached chemimechanical cellulose pulp in high yield of between 65 and 95% from particulate and preferably washed lignocellulosic material, such as wood chips, featuring the use of spent or waste bleaching liquid, preferably from a lignin-preserving bleaching process, in at least one stage of the process where a cooling and diluting liquid is required, such as during mechanical defibration of the material.

Process for manufacturing chemimechanical cellulose pulp in a high yield

Process and apparatus are provided for the preparation of improved high-yield cellulose pulps, such as semichemical, chemimechanical, thermomechanical, and mechanical pulps, which comprises mechanically defibrating a mixture of particulate lignocellulosic materials which have been partially pulped and softened to different extents. Part of the raw lignocellulosic material is particulate form is washed, moistened with steam, impregnated with pulping chemicals and pulped to a yield of from about 65 to about 92%. Another part is treated in similar manner but either not pulped at all or, if pulped, pulped to a lesser extent. The two parts are mixed without intermediate washing, after which the mixture is subjected to a vapor phase pulping by heating to a temperature within the range from about 90 to about 200.degree. C. under pressure to obtain softening of the lignin, and delignification, after which the resulting product is mechanically defibrated to form cellulose pulp.

Growing community of inventors

Husum, Sweden

Lars G Rudstrom