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Pulp and Paper 251

FIGURE 1 Overview of the recently completed bleached Kraft pulp mill built by Leaf River Forest Products in Mis-
sissippi. [Photo courtesy of Leaf River Corp.]

for wood pulping, and produced a range of pulp and pa- pulping liquor; (2) the Kamyr continuous digester, con-
per products with varying strength, printability, and other verting the industry from batch to continuous processes;
characteristics. (3) the sawmill debarker and chipper, making residues as
By 1900 a sufficient technology base was established to well as cordwood available as furnish; and (4) secondary
support the growth of the pulp and paper industry. Of par- innovations such as the diffusion washer and displacement
ticular importance was the Kraft process, and Kraft pulp- bleaching system.
ing has become the dominant method for liberating usable The thermomechanical pulping (TMP) invention in
fiber from wood. The domination of Kraft pulping became 1939, and the subsequent introduction of this technology
particularly pronounced after 1920. It was aided by the fol- from 1968–1973, and refiner mechanical pulping (RMP),
lowing inventions: (1) the Tomlinson furnace, permitting permitted the application of mechanical pulping systems
simultaneous energy and chemical recovery from spent to residue sources of wood. Their development spurred
the improvement of stone groundwood (SGW) pulping
by the introduction of pressurized groundwood (PGW)
TABLE I Dominant Process Inventions in the Pulp
and Paper Industry a systems.
This article is organized first to examine the issues as-
Year Pulping process invented
sociated with pulp mill raw materials. It then focuses on
1844 Groundwood mechanical pulping chemical pulping, mechanical pulping, bleaching, and pa-
1851 Soda pulping permaking. It is designed to overview the major technical
1866 Sulfite pulping concerns associated with these technologies.
1880 Semichemical pulp
1884 Kraft (sulfate) pulping II. FURNISH FOR PULP AND PAPER
1939 Thermomechanical pulp
a The dominant raw material for pulp and paper is wood ei-
From Libby, C. E. (1962). “Pulp and Paper Science and
Technology,” Vol. 1, Pulp. McGraw-Hill, New York. therharvestedspecificallyforpulpproductionorproduced