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II
Mechanical Pulping
Jurgen Blechschmidt, Sabine Heinemann, and Hans-Ulrich Suss
Handbook of Pulp. Edited by Herbert Sixta
Copyright © 2006 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim
ISBN: 3-527-30999-3
©2006 WILEY-VCHVerlag GmbH&Co.
Handbook of Pulp
Edited by Herbert Sixta
Introduction
Jurgen Blechschmidt and Sabine Heinemann
There are two technological principles to produce paper pulp from wood, namely
Mechanical processes or chemical processes. Whereas in chemical pulping the
yields are only about 45–55%, mechanical pulping uses about 80–95% of the fiber
Wood. Whilst this represents a source for the economic potential of mechanical
Pulps, the higher yield results in certain unfavorable properties compared to
Chemical pulp. Thus, fromthe sameportion ofwood, a double quantity of mechanical
Pulp is produced compared to chemical pulp. The increasing demand for paper and
Board has led to a permanent increase in mechanical pulp production (Fig. 1.1).
Fig. 1.1 Worldwide development of mechanical pulp production [1].
Among the total amount of paper pulp produced, mechanical pulp accounts for
about 20%.
Although mechanical pulping is a thermomechanical process, chemical processes
May also play a certain role. The mechanical defibration of wood is carried
Out in two different ways (Fig. 1.2), namely as a grinding process or as a refining
Process. The following definitions have been formulated for the products of those
processes:
Handbook of Pulp. Edited by Herbert Sixta
Copyright © 2006 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim
ISBN: 3-527-30999-3
_ Mechanical pulp: this is manufactured by mechanical defibration
Using a variety of mechanical procedures.
_ Stone groundwood: this is manufactured from round logs in a
Grinder.
_ Refiner mechanical pulp: this is manufactured by the mechanical
Defibration of wood chips in a disc refiner.
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Composition in sulfate and sulfite | | | Fig. 1.2 An overview of the basic mechanical pulping procedures. |