Note: Descriptions are shown in the official language in which they were submitted.
CA 02445340 2003-10-24
METifOD FOR THE PRODU-CTYON OF FIBER P
Cross Reference to Related Anplxcations
This is a continuation of prior PCT application No. PCT/,EP02/0161 l, entitled
"IvIETHOD FOR THE PRODUCTION OF WOODPULP", filed February 13, 2002.
BACKGROUND OF THE INVENTION
1. li5ield of the invention,
The present invention relates to a method for the production of fiber pulp for
further
utilization in the production of a fiber web, especially a paper or cardboard
web.
2. Description of the related arx.
Fiber pulp is produced is pulp mills through various methods. The raw
materials ate
natural raw materials, such as (predominantly) wood, straw, jute, etc. Wood
for example is
cooked in a cooking process and the pulp fibers are leached out and are
subjected to quality
improvement in further process steps (i.e. bleach, washing, etc.). At the end
of the process the
pulp is thickened, dried and transported to the paper mills, for example in
the form of bales.
There, the fiber pulps are again dissolved in Qulpe~rs and are prepared for
the paper
manufacturing process, for example refined and mixed with fillers. This can
occur thtough
direct addition of a filler, for exazuple calcium carbonate (CaC03), or
through loading of the
surfaces of the pulp fibers with a precipitated additive, for example, a
filler such as calcium
carbonate.
Loading with an additive, for example a filler, can occur through a chemical
precipitation
reacxi.an, especially through. a so-called "Fiber Loading'~'M" process, as
described in addition to
other publications, in U.S. Patent No. 5,223,090. In this type of "Fiber
LoadingTM" process at
least one additive, especially a filler is deposited onto the ru.oistened
fiber surfaces of the fibrous
material. The chemical precipitation reaction occurs preferably directly on
the fiber surfaces.
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The fibers can for example be loaded with calcium carbonate. Calcium oxide
and~ot calcium
hydroxide are added to the moist, disintegrated fibrous material so that at
least a part of this
associates itself with the water that is contained in the fibrous material.
The so treated fibrous
material is subsequently treated with carbon dioxide.
S When adding the medium containing the calcium oxide andlox the calcium
hydroxide to
the fiber stock suspension, a chemical reaction with exotherntal
characteristics occurs. The
calcium, hydroxide should preferably be added in liduid form (milk of lime).
'his implies that
the wager that is possibly embedded in or added to the fibrous materials of
the fiber stock
suspension is riot absolutely necessary for the start and devet.~pme,a ofthe
cremxcal aeavu~,u.
i0 SUMMARY OF THE ~1WENTION
~'he present invention provides a method ~or the production of fiber pulp that
will
increase tire efficiency of the utilized "Fiber Loadizxg''''~" process, as
well as the economic
efficiency of the raw material supply, especially i'or paper and cardboard
production.
The present inventive method provides for the production of pulp for
subsequent use in
15 the production of a fiber web, especially a paper or cardboard web. The
manufachired pulp is
first loaded with an additive by way of a chemical precipitation reaction. The
loaded pulp is then
dried at~d available for subsequent utilization or formulated into a suitable
~om1 for shipment.
The present inventive combination of the fiber pulp producctton with the
loading process
provides improved paper qualities. Since no drying occurs between the pulp
production process
20 and the loading procESS, more calcium hydroxide or calcium oxide can
penetrate through the
fiber walls, thereby allowing a greater filler content at the inner cell wall
suz~ace9 to be achieved
after the precipitation pzocess, and increasing the desired effect through
loading. Compared with
fiber pulp to which ~ller (calcium carbonate) was added in the conventional
method, the
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CA 02445340 2003-10-24
consistencies, optical characteristics, the specific volume (cm3/g) and the
porosity, as well as the
formation of the produced paper can be increased or improved.
An additional advantage of the present invention is that the fibers can be
loaded. centrally,
at the pulp mill. Therefore, only one single larger loading station for all
the pulp mill customers
combined is necessary. In contrast, if the loading process is decentralized,
then ata. individual
loading station is required for each customer. Overall, this loading process
is less ei~cient due to
cumulative longer downtimes and set-up times.
An additional advantage is found in that the pulp which is loaded with
precipitated filler
is easier to thicken and accordingly easier to dry. This results in pulp slabs
that are produ~.Pxi ~r
the pulp mill for shipment and that are generally several tithes thicket than
paper (> 1000 g/ma)
can be dried economically to a much higher level of dry content than
previously. Since
correspondingly less water needs to be ttansported, shipping costs are
reduced. At the same time
considerable energy savings are possible when producing the same shipping dxy
content.
A further advantage is that due to the combination ofthe pulp production and
the loading
processes, the strength potential of the fibers, and accordingly, the strength
of the paper that is
subsequently produced in the paper mill, can be considerably increased or,
that less fiber material
is required for a given paper consistency. On the one hand this is attributed
to the fact that
through the combination of the loading pxocess at the time of the pulp
production, considerably
more calcium carboxzate reaches the inside of the fibers since the fiber walls
are still soaked,
thereby facilitating penetration of, for example, milk of lime. On the other
hand it is also
attributed to that, for a desired filler content in the paper, a portion of
the filler is bonded inside
the lumen o~the fibers. Therefore the fiber bonding points oa the outside
surface of the fibers
ate not blocked.
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CA 02445340 2003-10-24
In accordance with an advantageous practical arrangement of the present
invention, the
fiber pulp is subjected to bleaching, either after, or in combination with the
fiber loading process.
At least one bleaching agent such as peroxide, chlorine, oxygen, ozone and/or
similar agents can
be added to the fiber pulp. Bleaching may also occur in multiple stages with
various bleaching
ageo~ts. It is especially advantageous that the bleaching process can be
combined after the "Fiber
Loading'''A'" process with the bleaching process that i,s generally conducted
in the pulp mill. This
reduces the expenditure for the chemical reagent preparation, as well as the
expenditure for
waste handling and reprocessing of the waste products accordingly.
Accordi..~.g to an advantageous armngem.~t of 'he present invention the fiber
pulp
possesses a dry content after the drying process that is greater than 80%,
especially greater than
85%, advantageously greater than 90% and preferably greater than 95%. If
necessary, the pulp
may be refined after the loading process, thereby still furfiher increasing
the level of &eeness and
strength potential. As already mentioned, the ~xber pulp can be loaded,
especially with
precipitated calcium carbonate.
The pulp production process can for example include the coolang of natural
fibers.
Advantageously, the pulp is supplied in the form of bales, rolls or similar
forms for filzther use ox
for shipment. The present invention is also applicable with semu-fiber pulp
and mechanical
pulps (stone ground wood, GMP, brown mechanical pulp, refiner mechanical pulp
RMP, thermo-
mechanical pulp TMP, C"TMP).
The present invention can be utilized advantageously with fiber pulps that are
produced
according to the sulfate process andlor according to the sulfite process. In
the sulfate pulping
process calcium hydroxide is used for the chemical recovery. l;lere too, a
clear syl~ergetic effect
is achieved by the present inventive combination of the relating process
steps. In addition, it is
advantageous when considering the economic supply of raw materials, a fiber
pulp that was
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CA 02445340 2003-10-24
produced according to the present inventive process is used in producing a
fiber web, especially
a paper or cardboard web.
When loading the fibers with, for example a filler, calcium carbonate (CaC03)
is
deposited on the moistened fiber surfaces by adding calcium oxide (Ca0) and/or
calcium
hydroxide (Ca(OI-1]Z) to the moist fiber material, whereby at least a part of
which can associate
itself with the water of the fibrous stock volume. The thereby treated fiber
material is they
treated with carbon dioxide (C02). The term 'moistened fiber surfaces" can
encompass all
moistened surfaces of the individual fibers. This specifically also includes
the scenario where
the fibexs are loaded w~~th calci~,~ carbonate or any other desired
precip;~ant cn tbcir ou~siu
surfaces as well as on their. inside (Lumen).
According to the present invention the fibers are loaded with the filler
calcium carbonate,
whereby the loading onto the moistened fiber surfaces occurs through a so-
called "Fiber
LoadingTM" process, as described in U.S. Patent No. 5,223,090. 1.n this "Fiber
Loading'iM"
process the carbon dioxide with the calcium hydroxide reacts to water and
calcium carbonate.
BRIEF DESC)~PT'ION OF THE D~tAWINGS
The above-mentioned and other features and advantages of this invention, and
the
manner of attaining them, will become more apparent and the invention will be
better understood
by reference to the following description of an embodiment of the invention
taken in conjunetivn
with the a,ccompaaying drawing, which is a schematic view of an embodiment of
the present
invention. 'fb~e exemplification set out herein illustrates one preferred
ernbodim.ent of the
invention, in one form, and such exemplification is not to be construed as
limiting the scope of
the invention, in any manner.
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CA 02445340 2003-10-24
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, an initial process step 10 includes a fiber pulp
preparation.
and production. The fiber pulp created through this production process is then
loaded with an
addifiive, for example a ~xller in a subsequent process step 12 by way of a
chemical precipitation
S reaction.
Especially calcium oxide and/or calcium hydroxide (slaked lime) is added to
the fiber
material irt such a way that at least a portion of this can, associate itself
with the water that is
contained in the fiber material, i.e. between the fibers, in, the hollow
fibers and in their walls, thus
ereatmg the following chemical reaction:
Ca0 + 1-IZO --> Ca(OH~
Slaking of caustic lime calcium hydroxide
The fiber material is then treated with. carbon dioxide (C02) in the relevant
reactor, so
that calcium carbonate (CaCO3) is extensively deposited on the moistened fiber
surfaces. This
results in the following chemical reaction:
Fiber Loading: Ca(OH)2 + COZ --~ CaC02 + H20
(Calcium carbonate + water)
Thickening and drying of the pulp (see process step 1.4) occurs following this
fiber
loading process. The loaded, thickened and dried pulp is then prepared for
application or for
shipment 16 (i.e. bales, roles, etc.).
While this invention has been described as having a preferred design, the
present
invention can be further modified within the spirit and scope of this
disclosure. This application
is therefore intended to cover any variations, uses, or adaptations of the
invention using its
general principles. Further, this application is intended to cover such
departures froze the present
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CA 02445340 2003-10-24
disclosure as come within known or customary practice in the art to which this
i.nventian pertains
and which fall within the limits of the appended claims.
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CA 02445340 2003-10-24
Component identification
Fiber pulp production process
12 Fiber loading process
14 Thickenixag~ Dry'mg
16 Shippin4g
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