- •Recovered Paper and Recycled Fibers
- •Isbn: 3-527-30999-3
- •Introduction
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •2006, Isbn 3-527-30997-7
- •Volume 1
- •Isbn: 3-527-30999-3
- •4.1 Introduction 109
- •4.2.5.1 Introduction 185
- •4.3.1 Introduction 392
- •5.1 Introduction 511
- •6.1 Introduction 561
- •6.2.1 Introduction 563
- •6.4.1 Introduction 579
- •Volume 2
- •7.3.1 Introduction 628
- •7.4.1 Introduction 734
- •7.5.1 Introduction 777
- •7.6.1 Introduction 849
- •7.10.1 Introduction 887
- •8.1 Introduction 933
- •1 Introduction 1071
- •5 Processing of Mechanical Pulp and Reject Handling: Screening and
- •1 Introduction 1149
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •150.000 Annual Fiber Flow[kt]
- •1 Introduction
- •1 Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •Void volume
- •Void volume fraction
- •Xylan and Fiber Morphology
- •Initial bulk residual
- •4.2.5.1 Introduction
- •In (Ai) Model concept Reference
- •Initial value
- •Validation and Application of the Kinetic Model
- •Inititial
- •Viscosity
- •Influence on Bleachability
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Introduction
- •International
- •Impregnation
- •Influence of Substituents on the Rate of Hydrolysis
- •140 116 Total so2
- •Xylonic
- •Viscosity Brightness
- •Xyl Man Glu Ara Furf hoAc XyLa
- •Initial NaOh charge [% of total charge]:
- •Introduction
- •Isbn: 3-527-30999-3
- •Introduction
- •Isbn: 3-527-30999-3
- •Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •In 1950, about 50% of the global paper production was produced. This proportion
- •4.0% Worldwide; 4.2% for the cepi countries; and 4.8% for Germany.
- •1150 1 Introduction
- •1 Introduction
- •1 Introduction
- •Virgin fibers
- •74.4 % Mixed grades
- •Indonesia
- •Virgin fibers
- •Inhomogeneous sample Homogeneous sample
- •Variance of sampling Variance of measurement
- •1.Quartile
- •3.Quartile
- •Insoluble
- •Insoluble
- •Insoluble
- •Integral
- •In Newtonion liquid
- •Velocity
- •Increasing dp
- •2Α filter
- •0 Reaction time
- •Increasing interaction of probe and cellulose
- •Increasing hydrodynamic size
- •Vessel cell of beech
- •Initial elastic range
- •Internal flow
- •Intact structure
- •Viscosity 457
- •Isbn: 3-527-30999-3
- •1292 Index
- •Visbatch® pulp 354
- •Index 1293
- •1294 Index
- •Impregnation 153
- •Viscosity–extinction 433
- •Index 1295
- •1296 Index
- •Index 1297
- •Inhibitor 789
- •1298 Index
- •Index 1299
- •Impregnation liquor 290–293
- •1300 Index
- •Industries
- •Index 1301
- •1302 Index
- •Index 1303
- •Xylose 463
- •1304 Index
- •Index 1305
- •1306 Index
- •Index 1307
- •1308 Index
- •In conventional kraft cooking 232
- •Visbatch® pulp 358
- •Index 1309
- •In prehydrolysis-kraft process 351
- •Visbatch® cook 349–350
- •1310 Index
- •Index 1311
- •1312 Index
- •Viscosity 456
- •Index 1313
- •Viscosity 459
- •Interactions 327
- •1314 Index
- •Index 1315
- •Viscosity 459
- •1316 Index
- •Index 1317
- •Xylose 461
- •Index 1319
- •Visbatch® pulp 355
- •Impregnation 151–158
- •1320 Index
- •Index 1321
- •1322 Index
- •Xylan water prehydrolysis 333
- •Index 1323
- •1324 Index
- •Viscosity 459
- •Index 1325
- •Xylose 940
- •1326 Index
- •Index 1327
- •In selected kinetics model 228–229
- •4OMeGlcA 940
- •1328 Index
- •Index 1329
- •Intermediate molecule 164–165
- •1330 Index
- •Viscosity 456
- •Index 1331
- •1332 Index
- •Impregnation liquor 290–293
- •Index 1333
- •1334 Index
- •Index 1335
- •1336 Index
- •Impregnation 153
- •Index 1337
- •1338 Index
- •Viscose process 7
- •Index 1339
- •Volumetric reject ratio 590
- •1340 Index
- •Index 1341
- •1342 Index
- •Index 1343
- •1344 Index
- •Index 1345
- •Initiator 788
- •Xylose 463
- •1346 Index
- •Index 1347
- •Vessel 385
- •Index 1349
- •1350 Index
- •Xylan 834
- •1352 Index
Isbn: 3-527-30999-3
©2006 WILEY-VCHVerlag GmbH&Co .
Handbook of Pulp
Edited by Herbert Sixta
1
Introduction
Herbert Sixta
1.1
Introduction
Industrial pulping involves the large-scale liberation of fibers from lignocellulosic
plant material, by either mechanical or chemical processes. Chemical pulping
relies mainly on chemical reactants and heat energy to soften and dissolve lignin
in the plant material, partially followed by mechanical refining to separate fibers.
Mechanical pulping involves the pretreatment of wood with steam (and sometimes
also with aqueous sulfite solution) prior to the separation into fibrous material
by abrasive refining or grinding. Depending on its end-use, the material recovered
from such processes – the unbleached pulp – may be further treated by
screening, washing, bleaching and purification (removal of low molecular-weight
hemicelluloses) operations.
For any given type of production, the properties of the unbleached pulp are determined
by the structural and chemical composition of the raw material. The
variation in fiber dimension and chemical composition of some selected fibers is
detailed in Tab. 1.1.
By far, the predominant use of the fiber material is the manufacture of paper,
where it is re-assembled as a structured network from an aqueous solution. Fiber
morphology such as fiber length and fiber geometry have a decisive influence on
the papermaking process. A high fiber wall thickness to fiber diameter ratio
means that the fibers will be strong, but that they may not be able to bond as effectively
with each other in the sheet-forming process. Another property which is
important to fiber strength is the spiral angle of the longitudinal cellulose micelle
chains which constitute the bulk of the fiber walls. Moreover, certain chemical
properties of the fibers and the matrix material in which they are embedded must
also be taken into account.
3
Handbook of Pulp. Edited by Herbert Sixta
Copyright © 2006 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim
Isbn: 3-527-30999-3
1 Introduction
Tab. 1.1 Fiber dimensions and chemical composition of some selected
agricultural and wood fibers (adopted from [1–6]).
Cell dimensions Chemical Composition
Fiber type Length
[mm]
Diameter
[lm]
Cellulose
%
Pentosan
%
Lignin
%
Ash
%
SiO2
%
average range average range
Stalk fibers (grass fibers)
Cereal straw
(wheat, corn, rice)
1.4 0.4–3.4 15 5–30 29–35a 26–32a 16–21a 4–9a 3–7a
Bamboo 2.7 1.5–4.4 14 7–27 26–43a 15–26a 21–31a 1.7–5a 1.5–3a
Sugarcane bagasse 1.7 0.8–2.8 34 32–44a 27–32a 19–24a 1.5–5a 0.7–3a
Bast fibers (single fibers)
Flax 33.0 9–70 19 5–38 64.1d 16.7d 2d 2–5a
Hemp 25.0 5–55 25 10–50 78.3d 5.5d 2.9d 0.5d
Jute 2–5 20 10–25 59.4d 18.9d 12.9d 0.6d <1a
Kenaf 3.4d 1.5–11d 24d 12–36d 31–39a 21–23a 15–18a 2–5a
Leaf Fibers
Abaca (long) 3–12d 10d 6–46d 61a 17a 9a <1a <1a
Sisal (long) 3.3d 0.8–8d 21d 7–47d 43–56a 21–24a 8–9a 0.6–1.0a <1a
Seed and fruit fibers
Cotton lint (raw) 20–50c 8–19c 88–96e 0.7–1.6e <1a
Cotton linters
(second cut, raw)
2–3c 17–27c 80c 2c <1a
Wood fibers
Softwood 3.3 1.0–9.0 33 15–60 40–44b (25–29)b 25–31b
Hardwood 1.0 0.3–2.5 20 10–45 43–47b 25–35b 16–24b
Adopted from Refs. [1a, 2b, 3, 4c, 5d and 6e].
Values in parentheses indicate total hemicellulase.
1.2
The History of Papermaking
The history of papermaking can be traced back to about ad 105, when Ts’ai-Loun
created a sheet of paper using old rags and plant tissues. In its slow travel westwards,
the art of papermaking reached Arabia in the middle of the eighth century,
from where it entered Europe via Spain in the 11th century. By the 14th century, a
number of paper mills existed in Europe, particularly in Spain, France, and Germany.
For centuries, paper had been made from linen, hemp and cotton rags.
After cleaning, sorting and cutting, these were boiled with potash or soda ash to
remove the remaining dirt and color. The operation was continued in a “breaking
engine” by adding fresh water until the cloth was separated into single fibers.
4
1.2 The History of Papermaking
Until the paper machine was constructed in 1799 by Louis-Nicholas Robert, the
final sheet-formation process was carried out manually.
Throughout the 18th century the papermaking process remained essentially
unchanged, with linen and cotton rags furnishing the basic fiber source. However,
the increasing demand for paper during the first half of the 19th century could no
longer be satisfied by the waste from the textile industry. Thus, it was evident that
a process for utilizing a more abundant material was needed. Consequently,
major efforts were undertaken to find alternative supplies for making pulp. As a
result, both mechanical and chemical methods were developed for the efficient
production of paper from wood. Mechanical wood pulping was initiated in 1840
by the German Friedrich Gottlob Keller. The wood-pulp grinding machine was
first commercialized in Germany in 1852 (Heidenheim) on the basis of an
improved technology developed by Voelter and Voith. However, mechanical pulping
did not come into extensive use until about 1870 when the process was modified
by a steam pretreatment which softens the inter-fiber lignin. Paper made
from mechanical wood pulp contains all the components of wood and thus is not
suitable for papers in which high brightness, strength, and permanence are required.
The clear deficiencies compared to paper made from cotton rags made it necessary
to strengthen the development of chemical wood pulping processes, focusing
on the removal of accessorial wood components such as lignin and extractives.
The first chemical pulping process was the soda process, so-named because it
uses caustic soda as the cooking agent. This process was developed in 1851 by
Hugh Burgess and Charles Watt in England, who secured an American patent in
1854. A year later, the first commercial soda mill using poplar as raw material was
built on the Schuylkill River near Philadelphia under the direction of Burgess,
who served as manager of the mill for almost 40 years. Because this process consumed
relatively large quantities of soda, papermakers devised methods for recovering
soda from the spent cooking liquor through evaporation and combustion
of the waste liquor and recausticizing of the sodium carbonate formed. To compensate
for the losses, sodium carbonate had to be added to the causticizing unit.
Since the preparation of sodium carbonate from sodium sulfate was rather expensive
by using the Leblanc process, Carl Dahl in Danzig tried to introduce sodium
sulfate directly in place of soda ash in a soda pulping recovery system. This substitution
produced a cooking liquor that contained sodium sulfide along with caustic
soda. Fortunately, the pulp so produced was stronger than soda pulp and was
called “kraft” pulp, so named from the Swedish word for “strong”. The process,
which was patented in 1884 by Dahl, has also been termed the sulfate process
because of the use of sodium sulfate (salt cake) in the chemical make-up. As a
consequence, many soda mills were converted to kraft mills because of the greater
strength of the pulp. Kraft pulp, however, was dark in color and difficult to bleach
compared to the competing sulfite pulp. Thus, for many years the growth of the
process was slow because of its limitation to papers for which color and brightness
were unimportant. With the development of the Tomlinson [7,8] combustion furnace
in the early 1930s, and with the discovery of new bleaching techniques, par-
5