Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF INCREASING EFFICIENCY OF CHEMICAL ADDITIVES IN
PAPERMAKING SYSTEMS
FIELD OF THE DISCLOSURE
100011 The present disclosure relates to a method for increasing
efficiency of chemical
additives in papermaking systems. More specifically, the method manages an
amount of soluble
lignin in the process water of the pulping and papermaking systems though use
of specific
polymers.
BACKGROUND
100021 There is a need for papermakers to maximize the efficiency of
chemical additives in
various systems such as paper mills utilizing virgin pulp, highly or fully
closed recycled linerboard
mills, minimize fresh water consumption in pulping and papermaking, and
minimize the effluent
discharge. There is also a need for pulping efficiency increase, e.g. pulp
yield increase, brown
stock washing efficiency increase, energy efficiency increases in black liquor
evaporators and
other. The problem with declines in chemical efficiency of additives is
universal. The scarcity of
fresh water sources and ever increasing costs for fresh water use and effluent
discharge drive
papermakers in reducing fresh water consumption and recycling process water.
Many recycle
linerboard (RLB) mills today consume 5 m3 or less fresh water per 1 ton paper
produced.
100031 The amounts of dissolved impurities in water can grow
exponentially and cause many
problems in paper production. The problems include formation of deposits,
increase of smell, and
high levels of VFA, COD and conductivity. Increased levels of dissolved and
colloidal components
harm the efficiency of chemical additives e.g. strength, retention and
drainage polymers, sizing
agents etc. As a result, papermakers have to increase the consumption of
chemical additives.
However, at some point, an increase in polymer load does not help in reaching
the desirable
performance, especially in fully closed paper mills.
100041 Virgin linerboard mills though consume more fresh water than
those of recycle
linerboard mills, still face the same issues with reduced chemical efficiency.
In many virgin
linerboard mills chemical additives do not function well and in some cases
they do not function at
all.
100051 Efficiency of chemical additives such as retention and
drainage polymers, dry strength
agents, sizing agents, and waste water treatment polymers can increase with
removal of anionic
trash and more specifically with removal of soluble lignin species.
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[0006] Lignin, in addition to cellulose and hemicellulose, is one of
the main constituents of
wood. Lignin is a natural, highly aromatic and hydrophobic polymer. For the
production of printing
grade paper, most of the lignin gets disintegrated and removed from cellulose
by Kraft pulping.
Additional amounts of lignin are further reduced by series of bleaching and
washing stages.
However, for production of packaging paper grades, other pulp sources are
used. These include
virgin pulp, mechanical pulps, semi-chemical mechanical pulps, and recycled
fibers such as OCC
(old corrugated containers), and the like. These grade pulps may include
significant amounts of
lignin.
[0007] The prior art describes several compositions or applications
for the improvements in
lignocellulosic paper quality. The prior art deals with residual lignin and/or
other contaminants
present in the fiber or on the surface of the fiber. However, no prior art
addresses issues of soluble
lignin in process water and the effects of process water containing high
amounts of soluble lignin
on papermaking processes. The efficiency of chemical additives will suffer
regardless of the
presence of contaminants in the fiber if the quality of process water is
compromised.
100081 Moreover, the presence of soluble lignin fragments in process
water is quite
problematic due to the accumulation of significant fractions of low molecular
weight lignin
species. The smaller soluble lignin fragments present in mill process water do
not have enough
affinity for cellulose fibers and hence continue to circulate in mill water
systems. Accordingly,
there remains an opportunity for improvement.
BRIEF SUMMARY
[0009] This disclosure addresses the issue of soluble dissolved
colloidal lignin in mill process
waters via a polymeric approach. This disclosure more specifically provides a
method of
increasing chemical efficiency of chemical additives in a papermaking system.
The method
includes the steps of providing thick stock pulp comprising soluble lignin,
process water, and at
least about 2% by weight of cellulosic fiber based on total weight of thick
stock pulp, and adding
at least one organic polymer to the thick stock pulp to reduce the amount of
soluble lignin therein.
Moreover, the organic polymer is chosen from cationic polymers, non-ionic
polymers and
combinations thereof.
[0010] This disclosure also provides an additional method of
increasing chemical efficiency
of chemical additives in a papermaking system. This method includes the steps
of providing thick
stock pulp comprising soluble lignin, process water, and at least about 2% by
weight of cellulosic
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fiber based on total weight of thick stock pulp, and adding at least one
inorganic coagulant to the
thick stock pulp to reduce the amount of soluble lignin therein.
BRIEF DESCRIPTION OF THE DRAWINGS
100111 The present disclosure will hereinafter be described in conjunction
with the following
drawing figures, wherein like numerals denote like elements, and
[0012] FIG. 1 is Table 1 referenced in the Examples and showing ABS, lignin
ppm, and % lignin
reduction as a function of treatment type;
[0013] FIG. 2A is Table 2 referenced in the Examples and showing lignin ppm in
water as a
function of treatment type and number of treatments;
[0014] FIG. 2B is a bar graph referenced in the Examples and showing % lignin
reduction as a
function of treatment type;
[0015] FIG. 3 is Table 3 referenced in the Examples and showing ABS, lignin
ppm, % lignin
reduction, COD ppm, and % COD reduction, as a function of treatment type;
[0016] FIG. 4A is Table 4 referenced in the Examples and showing % drainage
improvement as a
function of thick stock and thin stock treatment and polymer treatment;
100171 FIG. 4B is a bar graph referenced in the Examples and showing drainage
in seconds as a
function of treatment;
[0018] FIG. 4C is a bar graph referenced in the Examples and showing %
improvement of drainage
polymer efficiency as a function of treatment;
[0019] FIG. 5A is a table referenced in the Examples and showing lignin ppm, %
lignin reduction,
Mutek charge, and % reduction, as a function of treatment;
[0020] FIG. 5B is a line graph referenced in the Examples and showing lignin
reduction as a
function of date of measurement;
[0021] FIG. 6A is Table 6a referenced in the Examples and showing lignin ppm,
% lignin
reduction, turbidity, and % reduction in turbidity, as a function of treatment
type;
[0022] FIG. 6B is a line graph referenced in the Examples and showing lignin
reduction as a
function of date of measurement;
[0023] FIG. 6C is a line graph referenced in the Examples and showing pitch
control dosage as a
function of date of measurement;
100241 FIG. 6D is a line graph referenced in the Examples and showing sizing
agent dosage as a
function of date of measurement; and
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100251 FIG. 6E is Table 6e referenced in the Examples and showing various
properties measured
before and after various experimental trials.
DETAILED DESCRIPTION
100261 A method of removing soluble lignin in a papermaking system
is disclosed. The method
allows for an increase in chemical efficiency of papermaking additives
including strength
additives, retention and drainage polymers, sizing agents and others. In
addition, the novel method
allows for improvements in pulping sections as well by reductions in water use
in brown stock
wash. The present disclosure discloses a method for soluble lignin removal
from thick stock pulp
in papermaking process. The method includes adding a cationic or non-ionic
polymer to the thick
stock pulp. The method may also include adding and/or an inorganic coagulant a
cationic or non-
ionic polymer to the thick stock pulp of a papermaking system in highly closed
papermaking
systems. Lignin reduction from thick stock pulp and its fixation onto fiber
results in significant
improvements of chemical additives efficiency including those of strength,
sizing, retention and
drainage agents. In various embodiments, the thick stock pulp includes less
than about 5, 4, 3, 2,
1, 0.5, or 0.1, wt%, or is totally free of, an enzyme, e.g. a laccase enzyme
or any other enzyme
known in the art. Alternatively, the thick stock pulp may include any enzyme
known in the art in
the amounts set forth above. In various non-limiting embodiments, all values
and ranges of values
including and between those set forth above are hereby expressly contemplated
for use herein.
100271 Lignin reductions and its fixation to the fiber in thick
stock may also result in
improvements in pulping sections. These improvements could stem from
reductions in water use
in brown stock washings. These improvements could also include more efficient
pulp wash,
increased efficiency in black liquor evaporators, increased efficiency in
pulping and pulp yield
increase.
100281 With increasing degree of water closure, either due to
regulatory restrictions or water
scarcity, the efficiency of chemical additives declines. The decrease in
chemical efficiency, and in
some cases a complete lack of performance of polymeric additives, is generally
attributed to
organic contaminants, loosely defined species in the mill process waters
collectively referred to as
anionic trash. The anionic trash typically includes of extremely short fibers
called fines, degraded
starch, degraded or modified chemical additives such as polymers as well as
soluble dissolved
colloidal lignin. These components affect the performance of chemical
additives, in particular
cationic polymers, differently. Using a model white water system, based upon
the compositional
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analysis of several commercial recycled paper mills, the applicants
investigated the effect of
several troublesome components on cationic polymers. Lignin, although not the
most prevalent
species in mill process waters, showed the most adverse impact on chemical
efficiency.
100291 Lignin levels in process water may accumulate in highly
closed recycled paper mills.
They can also be very high in relatively open virgin mills due to insufficient
pulp wash. In either
case, lignin levels can be high enough to fully or partially deactivate
polymeric additives and hurt
their performance.
100301 The disclosure addresses the issue of soluble lignin in thick
stock pulp via a polymeric
approach. Soluble lignin can be removed from the papermaking process water by
a treatment
comprising addition of non-ionic and/or cationic polymers to the thick stock
pulp. As used herein,
the terminology dried furnish solids may be alternatively described as oven
dried cellulosic fiber.
100311 The non-ionic polymers useful in the disclosure include, but
are not limited to, poly-
oxazoline, polyethylene oxide (PEO), copolymers of polyethylene oxide or
polypropylene oxide
(PO), copolymers of polyethylene oxide and polypropylene oxide (E0/P0),
polyvinylpyrrolidone,
polyethylenimines (PEI) and/or their combinations. The PEO can be a homo-
polymer of ethylene
oxide, or a copolymer of ethylene oxide with propylene oxide and / or butylene
oxide. A
homopolymer of polyethylene oxide is the most typical. Examples of such
products are available
as dry powder products from Solenis LLC (Wilmington, DE) as Perform PB 8714
and Dow
Chemical (Midland, MI) as Ucarfloc 300,302, 304, and 309. The PEO homopolymer
is also
available as a slurry, where the PEO is dispersed in a medium. The medium can
be any one or
more of ethylene glycol, propylene glycol, poly(ethylene glycol),
poly(propylene glycol), glycerol,
and the like and or their combinations. Examples of a PEO slurry include Zalta
M_F 3000 from
Solenis LLC (Wilmington, DE).
100321 The non-ionic or cationic polymers useful in the present
disclosure can be of Formulas
I or II or III.
{-B (Formula I)
-FB-co-Cd- (Formula II)
{-CI- (Formula III)
100331 B represents one or more different nonionic repeat units
formed after polymerization
of one or more nonionic monomers.
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100341 C represents one of more different cationic repeat units
formed after polymerization of
one or more cationic monomers.
100351 The nonionic polymer segment B in Formulas I and II is a
repeat unit formed after
polymerization of one or more nonionic monomers. Exemplary monomers
encompassed by B
which are useful for the present disclosure include, but are not limited to,
acrylamide;
methacrylamide; N-alkylacrylamides, such as N-methylacrylamide; N,N-
dialkylacrylamide, such
as N,N-dimethylacrylamide; methyl methacrylate; methyl acrylate;
acrylonitrile; N-vinyl
methylacetamide; N-vinylformamide; N-vinylmethyl formamide; vinyl acetate; N-
vinyl
pyrroli done and mixtures of any of the foregoing. The disclosure contemplates
that other types of
nonionic monomer can be used, or more than one kind of non-ionic monomer can
be used.
Preferable nonionic monomers used are acrylamide; methacrylamide, N-
vinylformamide.
100361 The cationic polymer segment C in Formula II and III is the
repeat unit formed after
polymerization of one or more cationic monomers. Exemplary monomers
encompassed by C
which are useful for the present disclosure include, but are not limited to,
cationic ethylenically
unsaturated monomers such as the diallyldialkylammonium halides, such as
diallyldimethylammonium chloride; the (meth)acrylates of dialkylaminoalkyl
compounds, such as
dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethyl
aminopropyl
(meth)acrylate, 2-hydroxydimethyl aminopropyl (meth)acrylate, aminoethyl
(meth)acrylate, and
the salts and quaternaries thereof; the N,N-
dialkylaminoalkyl(meth)acrylamides, such as N,N-
dimethylaminoethylacrylamide, and the salt and quaternaries thereof and
mixtures of the
foregoing. Most typical are diallyldimethylammonium chloride (DADMAC) and
dimethylaminopropyl (meth)acrylamide (DIMAPA), dimethylaminoethyl
(meth)acrylate
(ADAME) and the salt and quaternaries thereof and mixtures of the foregoing.
100371 Another method to produce the cationic polymer of structure
II is by polymerization of
the monomer(s) followed by hydrolysis. The level of hydrolysis can be
expressed as
hydrolysis" or -hydrolysis %" on a molar basis. A hydrolyzed polymer can thus
be described by
as "% hydrolyzed." Moreover the level of hydrolysis can be approximated. For
the purposes of
applicants' disclosure, a poly(vinylamine) that is referred to as "50%
hydrolyzed" means from
about 40 to about 60% hydrolyzed. Likewise, a poly(vinylamine) that is about
100% hydrolyzed
means from about 80 to about 100% hydrolyzed. The hydrolysis reaction results
in the conversion
of some or all of the monomer(s) to amines, as controlling the hydrolysis
reaction can vary the
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resultant percentage of monomers having amine functionality. Poly(vinylamine)s
are useful in the
present disclosure. Examples of monomers used to make a poly(vinylamine)
include, but are not
limited to, N-vinylformamide, N-vinyl methyl formamide, N-vinylphthalimide, N-
vinylsuccinimide, N-vinyl-t-butylcarbamate, N-vinylacetamide, and mixtures of
any of the
foregoing. Most typical are polymers prepared by the hydrolysis of N-
vinylformamide. In the case
of copolymers, nonionic monomers, such as those described above, are the
typical comonomers.
Alternatively, poly(vinylamine) can be prepared by the derivatization of a
polymer. Examples of
this process include, but are not limited to, the Hofmann reaction of
polyacrylamide. It is
contemplated that other synthetic routes to a poly(vinylamine) or polyamine
can be utilized.
100381 Polymer dispersions such as described in US patent 7323510,
which is expressly
incorporated herein by reference in various non-limiting embodiments, can be
used in the present
disclosure. For example, a dispersion containing (i) a high molecular weight
cationic
polyacrylamide with a weight average molecular weight of greater than about
1,000,000, and (ii)
a highly charged (derived from greater than about 50%, typically about 60%
cationic monomers)
low molecular weight cationic dispersant polymer with a molecular weight of
between about
100,000 and about 500,000 can be used in the disclosure. Typical cationic
monomers for the
components of the dispersion are those listed for polymer segment C. In
various non-limiting
embodiments, all values and ranges of values including and between those set
forth above are
hereby expressly contemplated for use herein.
100391 The molar percentage of B:C of nonionic monomer to cationic
monomers of Formula
II may fall within the range of about 99:1 to about 1:99, or about 80:20 to
about 20:80, or about
75:25 to about 25:75 or about 40:60 to about 60:40 or about 99:1 to 50:50, and
most typical are
about 99:1 to about 90:10 where the molar percentages of B and C add up to
about 100%. It is to
be understood that more than one kind of nonionic or cationic monomer may be
present in Formula
II or III. In various non-limiting embodiments, all values and ranges of
values including and
between those set forth above are hereby expressly contemplated for use
herein.
100401 The cationic or non-ionic polymers used in the disclosure can
be manufactured and
supplied to the end user as a dry or granular powder, an aqueous solution, a
dispersion, or an
inverse emulsion.
100411 The molecular weight of the cationic or non-ionic polymers
can be from about 100,000
to about 10 million Da, typically greater than about 250,000. The molecular
weight of the cationic
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or non-ionic polymers can be from about 400,000 to about 10 million Da.
Usually higher molecular
weight of non-ionic polymer provides more efficient soluble lignin removal.
For instance when
using non-ionic polymers or dispersion polymers a molecular weight of about 1
million or greater
is typical. For highly charged (greater than 60% cationic monomer) cationic
polymers (DADMAC
or DIMAPA or EPI-DMA) molecular weight can be from about 100,000 to up to
about 1,000,000,
or typically from about 200,000 to up to about 500,000. Typically for low
charged cationic
polymers (10 mole percent or less of cationic monomer) molecular weight can be
from about
1,000,000 to up to about 10,000,000 Daltons. In various non-limiting
embodiments, all values and
ranges of values including and between those set forth above are hereby
expressly contemplated
for use herein.
100421 The non-ionic or cationic polymer dosage can be from 0.01 lbs
to 10 lbs. of polymer
solids per ton of oven dried pulp (e.g. dry furnish solids) or about 0.01 to
about 10, or about 0.05
to about 5, or about 0.1 to about 3 lbs, or about 0.1 to about 2 lbs. of
polymer solids (e.g. active
organic polymer) per ton of oven dried pulp (e.g. dry furnish solids). In
various non-limiting
embodiments, all values and ranges of values including and between those set
forth above are
hereby expressly contemplated for use herein.
100431 Soluble lignin removal may be further enhanced by combining
non-ionic or cationic
polymers with addition of inorganic cationic coagulants like polyaluminum
chloride, alum
(aluminum sulfate), aluminum chlorosulfate, aluminum chlorohydrate,
ferric(III) chloride,
ferric(III) sulfate, iron (II) chloride, iron (II) sulfate, polyferrous
sulfate, any other aluminum or
iron based cationic coagulant known to those of skill in the art. Inorganic
cationic coagulants
addition dosage can be from about 0.01 lb to about 12 lb of dry solids per
dried fiber solids, or
more specifically from about 0.05 to about 6 lb of dry solids per dried fiber
solids. In various non-
limiting embodiments, all values and ranges of values including and between
those set forth above
are hereby expressly contemplated for use herein.
100441 Soluble lignin reductions are accompanied with drop in
negative Mutek charge of both
lab generated or paper mill process waters. Mutek charge is defined as a
surface charge of colloid
species in the filtrate. Since soluble lignin is one of significant
contributors to negative Mutek
charge, soluble lignin reductions are expected to reduce negative Mutek charge
of process water
by at least about -50 l.tequiL, possibly by about -100 l.tequ/L, or by about -
200 pequ/L or more.
100451 Soluble lignin reductions in thick stock pulp by a polymer or
polymer combination
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treatment results in chemical efficiency improvements. These include but not
limited to the
efficiency of retention and drainage polymers, strength agents, sizing agents
and others.
100461 Soluble lignin reductions in thick stock pulp are expected to
have benefits not only in
chemical efficiency increase but also in the operations of primary clarifiers,
anaerobic and aerobic
digester plants, on waste water treatment overall due to removal of species
which are hard to
oxidize and remove by traditional methods of water remediation. Soluble lignin
removal and hence
chemical efficiency increase is also expected to reduce fresh water use and
water closure increase.
100471 Soluble lignin removal is expected to reduce COD (chemical
oxygen demand) of
process water and COD of waste water stream, including COD fractions which are
harder to
oxidize (or reduce) and which often require tertiary treatment with the use of
oxidizing agents.
That in its turn is expected to make waste water treatment more effective and
less expensive.
100481 Polymer can be applied to the thick stock pulp or parts of
the papermaking where
process water is mixed with cellulosic fiber, i.e. in a thin and/or thick
stock. The polymers can also
be added to the thin stock, where the thick stock is mixed with the process
white water at the
primary fan pump. Polymer addition points in the thin stock can include, but
are not limited to, the
inlet or discharge sides of the primary or secondary fan pump, cleaners, or
the inlet or discharge
of the pressure screen.
100491 However, the best efficiency is achieved by application of a
polymer product of a
combination of polymer products directly to a thick stock, e.g. blend chest,
machine chest. Thick
stock pulp may be defined as a mixture of process water and cellulosic fiber
with fiber consistency
to be about 2% or higher, e.g. from about 2 to about 3, about 3 to about 4,
about 2 to about 4, or
about 4, %. Application of a polymer in a thick stock enables soluble lignin
removal onto fiber and
thus into finished paper. Thin stock pulp may be defined as a mixture of
process water and
cellulosic fiber with fiber consistency to be less than about 2%, 15%, 1%, or
0.5%. In various
non-limiting embodiments, all values and ranges of values including and
between those set forth
above are hereby expressly contemplated for use herein.
100501 The proposed treatment can be found beneficial for polymer
additive efficiency in RLB
paper mills which utilize mainly OCC, also virgin mills utilizing unbleached
Kraft pulp (UKP),
semi-chemical mechanical pulps like neutral sulfite semi-chemical (NSSC),
combinations of
recycled and virgin pulps (e.g. NSSC/OCC), also deinked pulp (DIP), mechanical
pulps like
thermal mechanical pulp (TMP), recovered newspaper, recovered tissue or other
fiber sources.
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100511 Also provided is a method of increasing efficiency of
chemical additives in a
papermaking system comprising adding at least one polymer and at least one
inorganic coagulant,
to the thick stock pulp to reduce the amount of soluble lignin in the thick
stock pulp.
100521 In various embodiments, the method can provide additional
benefits to the pulping
sections of papermaking processes, though pulping sections precede the
papermaking machine and
the suggested soluble lignin treatment in the thick stock. This is because
effective lignin
management can allow for less condensed and/or fresh water use in brown stock
washings and
hence result in reductions of condensed and/or fresh water use. In addition,
the method may result
in higher solids in black liquor from washing processes.
100531 Black liquor volume reductions can also result in less energy
spending in black liquor
evaporators due to higher organic and inorganic solids in black liquor and
lower water usage in
brown stock wash. Black liquor evaporation is an energy intensive process. In
this process, black
liquor is condensed from about 15% solids to about 70% and higher by passing
through several
black liquor evaporators in which water is removed stepwise by evaporation to
steam. Even small
increases in % solids of the original black liquor can result in significant
energy savings.
100541 Alternatively, the method can also help producing more pulp
and/or result in increasing
a number of cooks or a cooking efficiency increase because brown stock washing
becomes more
efficient with lignin fixation and removal in the papermaking section. For
example, a pulp yield
increase could be about 1% to about 2%, about 3% to about 4%, about 4% to
about 6%, about 7%
to about 8 %, about 9 to about 10% or higher, or from about 1 to about 10,
about 2 to about 9,
about 3 to about 8, about 4 to about 7, or about 5 to about 6, %, depending on
the needs of the
pulping and papermaking. Due to effective lignin management, the pulping
section can have more
leverage in cooking pulp to lower the Kappa number value.
100551 In various embodiments, this disclosure describes the use of
polymer(s) in the thick
stock of a papermaking section, e.g. in a blend chest, machine chest, or stuff
box, or via
simultaneous application at various points in the papermaking process.
However, this method may
also be beneficial in application of lignin fixation polymer or polymers in
alternative segments of
the papermaking or pulping sections. These could include application of lignin
fixation polymers
to the last stages of brown stock washing, e.g. drum displacement (DD) washing
or last stages of
a bleach plant, e.g. after extraction stages, or before or after dewatering
stages, or in the thin stock
of the papermaking process.
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[0056] In a bleaching plant, after pulp is bleached and washed, it
is dewatered (using a decker)
and usually stored in a hi density (HiD) storage chest until it is needed by
the papermill. The
application of lignin fixation and removal polymers could be beneficial if
added after the washing
but before the dewatering decker since at that point most of the impurities
would be removed with
washing water. Lignin fixation and removal polymers can also be added after
pulp thickening,
though the contact time could by significantly higher at that point.
[0057] If no bleaching stages are used, then a storage tank of
unbleached pulp after brownstock
washing and dewatering could be utilized as a location wherein polymer(s) are
added for lignin
fixation and removal. Alternatively, polymer(s) can be added to the last
stages of brown stock
washing. This approach also could allow using less water in brownstock washing
or shorter time
of washing (or both), overall allowing for a pulp production rate increase.
Additional Embodiments.
[0058] In various embodiments, this provides a method of increasing
chemical efficiency of
chemical additives in a papermaking system. The method also provides for
improvements in a
pulping section in the form of increased efficiency in pulp production,
increased efficiency in pulp
wash and black liquor recycling upon burning in boilers as well as increased
steam production.
The method includes the steps of providing thick stock pulp comprising soluble
lignin, process
water, and at least about 2% by weight of cellulosic fiber based on total
weight of thick stock pulp,
and adding at least one organic polymer to the thick stock pulp to reduce the
amount of soluble
lignin therein. Moreover, the organic polymer is chosen from cationic
polymers, non-ionic
polymers and combinations thereof This method also provides an additional
method of increasing
chemical efficiency of chemical additives in a papermaking system. This method
includes the
steps of providing thick stock pulp comprising soluble lignin, process water,
and at least about 2%
by weight of cellulosic fiber based on total weight of thick stock pulp, and
adding at one polymer
and at least one inorganic coagulant to the thick stock pulp to reduce the
amount of soluble lignin
therein.
[0059] In one embodiment, the organic polymer is cationic. In
another embodiment, the
cationic polymer has the general formula II: [ B co C-], wherein B represents
one or more different
nonionic repeat units formed after polymerization of one or more nonionic
monomers and C
represents one of more different cationic repeat units formed after
polymerization of one or more
cationic monomers. In another embodiment, the molar percentage of B: C of
nonionic monomer to
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cationic monomer of Formula II is about 99:1 to about 1:99, or about 80:20 to
about 20:80, or
about 75:25 to about 25:75 or about 40:60 to about 60:40 or about 99:1 to
about 50:50. In a further
embodiment, the molar percentage of B:C of nonionic monomer to cationic
monomer of Formula
II is about 99:1 to about 90:10. In still another embodiment, the organic
polymer has the general
formula II: [ C-], wherein C represents one of more different cationic repeat
units formed after
polymerization of one or more cationic monomers. In a further embodiment, the
cationic or non-
ionic polymer is chosen from cationic polyacrylamides, polyvinylamines,
polyethyleneimines,
diallyldimethylammonium chloride polymers, trialkylamminoalkyl
(meth)acrylamide polymers,
epi chl orohydrin-dim ethyl amine copolymers, polyethyl en eoxi de polymers,
polyethyl en eoxi de
/polypropyleneoxide copolymers, poly-oxazolines and combinations thereof.
Alternatively, the
cationic polyacrylamides is derived from at least one monomer chosen from
diallyldimethylammonium chloride, N,N,N-trialkylamminoalkyl (meth)acrylate,
N,N,N-
trialkylamminoalkyl (meth) acrylamide, epichlorohydrin-dimethylamine and
combinations
thereof. Moreover, the cationic polymer may include a polyvinylamine, wherein
the
polyvinylamine is derived from at least one monomer chosen from N-
vinylformamide, N-vinyl
methyl formamide, N-vinylphthalimide, N-vinylsuccinimide, N-vinyl-t-
butylcarbamate, N-
vinylacetamide, and mixtures of any of the foregoing, wherein typically at
least one monomer is
N-vinylformamide. In another embodiment, the cationic polymer is a polymer
dispersion
comprising (i) a high molecular weight cationic polyacrylamide and (ii) a low
molecular weight
highly changed cationic dispersant polymer. In yet another embodiment, the
weight average
molecular weight of the non-ionic or cationic polymer is from about 100,000 to
about 10 million
Da and typically about 400,000 to about 10 million Da. Alternatively, the
organic polymer is non-
ionic. Moreover, the weight average molecular weight of the non-ionic polymer
may be from about
400,000 to about 10 million Da and typically about 1,000,000 to about
10,000,000 Da. In various
non-limiting embodiments, all values and ranges of values including and
between those set forth
above are hereby expressly contemplated for use herein.
100601 In other embodiments, the disclosure provides a method of
increasing efficiency of
chemical additives in a papermaking system comprising adding at least one
organic polymer to the
thick stock pulp to reduce the amount of soluble lignin in the thick stock
pulp; wherein the organic
includes polyethyleneoxide polymer with a weight average MW of greater than
about 1,000,000
and less than about 10 million daltons. Alternatively, the disclosure provides
a method of
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increasing efficiency of chemical additives in a papermaking system comprising
adding at least
one organic polymer to the thick stock pulp to reduce the amount of soluble
lignin in the thick
stock pulp; wherein the organic polymer includes cationic polyacrylamide with
a weight average
1\4W of greater than about 200,000 and less than about 10 million daltons. In
other embodiments,
the organic polymer is added to the thick stock pulp in an amount of from 0.01
lbs to 10 lbs. of
polymer solids per ton of oven dried pulp (e.g. dry furnish solids) or about
0.01 to about 10, or
about 0.05 to about 5, or about 0.1 to about 3 lbs. of polymer solids (e.g.
active organic polymer)
per ton of oven dried pulp (e.g. dry furnish solids). In still other
embodiments, the at least one
organic polymer are added to the thick stock pulp, wherein the thick stock
pulp may be a slurry of
process water and cellulosic fiber with a consistency of about 2% or higher.
Alternatively, the at
least one organic polymer and at least one inorganic coagulant are added in a
simultaneous or
concurrent manner to the thick stock pulp, wherein the thick stock pulp may be
defined as a slurry
of process water and cellulosic fiber with a consistency of about 2% or
higher. In further
embodiments, the organic polymer includes a homopolymer. Alternatively, the
organic polymer
includes a copolymer. In various non-limiting embodiments, all values and
ranges of values
including and between those set forth above are hereby expressly contemplated
for use herein.
100611 In still other embodiments, the removal of soluble lignin is
monitored by reduction in
absorbance in UV-VIS spectra at about 280 nm and the reduction in absorbance
is about 5% or
higher after about 24 hours as compared to the system before the laccase and
the cationic or non-
ionic polymer were added to the thick stock. Alternatively, the thick stock
pulp includes a
cellulosic fiber source, wherein the cellulosic fiber source is chosen from
OCC, deinked pulp,
virgin fiber, mechanical pulp, unbleached Kraft pulp or the mixtures thereof
Still further, the thick
stock pulp can include a cellulosic fiber source, wherein the cellulosic fiber
source includes
recycled paper. In other embodiments, at least one chemical additives in the
papermaking system
is chosen from retention and drainage polymers, strength agents and sizing
agents and
combinations thereof. In still further embodiments, COD is reduced by at least
about 5% in the
process water or waste water streams as compared to the COD compared to the
system before the
cationic or non-ionic polymer or polymer combinations were added to the thick
stock. Even
further, the method may further include addition of inorganic coagulants to
the thick stock. In other
embodiments, the inorganic coagulants are chosen from aluminum sulfate,
aluminum chloride,
aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, iron
(III) chloride, iron
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(III) sulfate iron (II) chloride, iron (II) sulfate, polyferrous sulfate, and
combinations thereof. In
various non-limiting embodiments, all values and ranges of values including
and between those
set forth above are hereby expressly contemplated for use herein.
[0062] This disclosure also provides a method that includes the
steps of providing thick stock
pulp comprising soluble lignin, process water, and at least about 2% by weight
of cellulosic fiber
based on total weight of thick stock pulp, and adding the at least one organic
polymer and at least
one inorganic coagulant to the thick stock pulp to reduce the amount of
soluble lignin therein. In
other embodiments, the inorganic cationic coagulant is added to the
papermaking system in an
amount of from about 0.01 lb to about 12 lb of dry solids per ton of dried
fiber solids, or more
specifically from about 0.05 to about 6 lb of dry solids per ton of dried
fiber solids. In various non-
limiting embodiments, all values and ranges of values including and between
those set forth above
are hereby expressly contemplated for use herein.
[0063] In various embodiments, this disclosure provides a method of
increasing efficiency of
chemical additives in a papermaking system wherein the method includes the
step of providing
thick stock pulp comprising soluble lignin, process water, and at least about
2% by weight of
cellulosic fiber based on total weight of thick stock pulp, and adding at
least one organic polymer
to the thick stock pulp to reduce the amount of soluble lignin therein.
Moreover, the organic
polymer is chosen from cationic polymers, non-ionic polymers and combinations
thereof. In
another embodiment, the thick stock pulp includes at least about 3 or 4% by
weight of the cellulosic
fibers based on a total weight of the process water. In such embodiments, the
cellulosic fibers are
derived from NSSC pulp, OCC pulp, deinked pulp, virgin fiber, mechanical pulp,
unbleached
Kraft pulp or combinations thereof. In a further embodiment, the organic
polymer is cationic and
has the general formula II: [B-co-C] (II) wherein B is one or more nonionic
repeat units formed
after polymerization of one or more nonionic monomers, C is one or more
different cationic repeat
units formed after polymerization of one or more cationic monomers, and -co-
is indicative of the
polymer being a co-polymer of B and C. In another embodiment, a molar
percentage of B:C of the
nonionic monomer to the cationic monomer of Formula II is about 75:25 to about
25.75. In still
another embodiment, the organic polymer has the general formula III: [-C-]
wherein C is one or
more different cationic repeat units formed after polymerization of one or
more cationic
monomers. In a further embodiment, the organic polymer is chosen from cationic
polyacrylamides,
polyvinylamines, polyethyleneimines, diallyldimethylammonium chloride
polymers,
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trialkylamminoalkyl (meth)acrylamide polymers, epichlorohydrin-dimethylamine
copolymers,
polyethyleneoxide polymers, polyethyleneoxide-polypropyleneoxide copolymers,
poly-
oxazolines, and combinations thereof. In still a further embodiment, the
cationic polyacrylamides
are derived from at least one monomer chosen from diallyldimethylammonium
chloride, N,N,N-
trialkylamminoalkyl (meth)acrylate, N,N,N-trialkylamminoalkyl (meth)
acrylamide,
epichlorohydrin-dimethylamine and combinations thereof. In another embodiment,
the cationic
polymer includes a polyvinylamine derived from at least one monomer chosen
from N-
vinylformamide, N-vinyl methyl formamide, N-vinylphthalimide, N-
vinylsuccinimide, N-vinyl-t-
butyl carb am ate, N-vinyl acetami de, and combinations thereof. In yet
another embodiment, the
organic polymer is a polymer dispersion comprising (i) a high molecular weight
cationic
polyacrylamide having a weight average molecular weight of greater than about
1,000,000 g/mol
and (ii) a low molecular weight cationic dispersant polymer derived from
greater than about 50
wt% of cationic monomers and having a weight average molecular weight of from
about 100,000
to about 500,000 g/mol. In an additional embodiment, the weight average
molecular weight of the
non-ionic or cationic polymer is from about 100,000 to about 10 million Da. In
another
embodiment, the organic polymer is non-ionic and has a weight average
molecular weight of from
about 1,000,000 to about 10,000,000 Da. In another embodiment, the organic
polymer is a
polyethyleneoxide polymer having a weight average molecular weight of greater
than about
1,000,000 and less than about 10 million Da. In a further embodiment, the
organic polymer is
cationic polyacrylamide having a weight average molecular weight of greater
than about 200,000
and less than about 10 million Da. In another embodiment, the organic polymer
is added to the
thick stock pulp in an amount of from about 0.05 to about 5 pounds of the
organic polymer (e.g.
active organic polymer) per ton of dried furnish solids, i.e., oven dried
cellulosic fiber. In a further
embodiment, the reduction in the amount of soluble lignin in the thick stock
pulp is evidenced by
at least a 5% reduction in absorbance in a UV-VIS spectra measured at about
280 nm after 24
hours as compared to process water that is free of the at least one organic
polymer. In another
embodiment, the process water exhibits a chemical oxygen demand that is
reduced by at least
about 5% as compared to the chemical oxygen demand of process water that is
free of the at least
one organic polymer. In a further embodiment, the method includes the step of
adding an inorganic
coagulant to the thick stock pulp wherein the inorganic coagulant is chosen
from aluminum sulfate,
aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum
sulfate, iron
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OM chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate,
polyferrous sulfate, and
combinations thereof. In various non-limiting embodiments, all values and
ranges of values
including and between those set forth above are hereby expressly contemplated
for use herein.
100641 This disclosure also provides for a method to achieve
improvements in pulping section,
e.g. increasing pulping yield and efficiency, improvements and energy
reductions in black liquor
evaporators, reductions in water use in brown stock washing etc. These
improvements are reached
by providing thick stock pulp comprising soluble lignin, process water, and at
least about 2% by
weight of cellulosic fiber based on total weight of thick stock pulp, and
adding at least one organic
polymer to the thick stock pulp to reduce the amount of soluble lignin
therein. Moreover, the
organic polymer is chosen from cationic polymers, non-ionic polymers and
combinations thereof
100651 In still other embodiments, the method further includes the
steps of providing thin stock
pulp, and adding the at least one organic polymer to the thin stock pulp
simultaneously with the
step of adding the at least one organic polymer to the thick stock pulp.
100661 In further embodiments, the method of this disclosure
increases pulp yield by at least
about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5
or 10% (or greater) as measured
in tons of pulp produced per day. For example, because this method is more
efficient than other
methods, additional pulp can be produced at the front end of the process,
i.e., before the step of
providing the thick stock pulp. The increase in pulp yield can be determined
as compared to a
comparative process that does not utilize the at least one organic polymer of
this disclosure. In
various non-limiting embodiments, all values and ranges of values including
and between those
set forth above are hereby expressly contemplated for use herein.
100671 In other embodiments, the method further includes the step of providing
a black liquor that
has a percent solids that is at least 0.5% higher than a comparative method
that does not utilize the
at least one organic polymer. Said differently, the instant disclosure allows
for "dirtier" solutions
to be utilized. In various embodiments, the black liquor that can be utilized
in this method can
have a percent solids that is at least about 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5,
4, 4.5, 5, percent greater
(or even more) than a comparative method that does not utilize the at least
one organic polymer.
This increase in solids means that dirtier black liquor streams can be
utilized. This reduces
production times, complexities, and costs. In various non-limiting
embodiments, all values and
ranges of values including and between those set forth above are hereby
expressly contemplated
for use herein.
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EXAMPLES
[0068] Polymer products used in this testing are Product A (water
dispersion of cationic
polyacrylamide, 28% actives), and Product B (25% active polyethylene oxide
dispersion product),
Product C (40% active, polydadmac based product), Product D (24% active
polyethyleneimine),
Product E (13% active anionic acrylamide), Product F (20% active amphoteric
acrylamide), and
Product G (water dispersion of cationic polyacrylamide, 33% actives) all
Solenis LLC products.
Addition levels of polymers are given in pounds (or kg) of active polymer per
ton of dried paper.
In the lab setting polymer products are dissolved in water to make 2,500 ppm
solutions prior to
their additions to process water or stock.
[0069] Testing was conducted using thick stock pulp (OCC, UKP, TMP)
having a 3.6 to 4%
consistency from blend chests of paper machines and white water collected from
headbox or a
synthetic furnish was made by mixing cellulosic fiber with synthetic white
water. The pH of the
thick stock and white water samples varied within 6.0 to 7.5.
[0070] Synthetic white water used for testing was made by addition
of several inorganic
components (calcium chloride, sodium sulfate, and sodium acetate) and organic
components
(anionic starch, soluble lignin, sodium polyacrylate, sodium oleate, acetic
acid and galactauronic
acid). The conductivity of the resulting mixtures was from 4,700-5,000 uS/cm
and pH was from
6.1-6.5. Experiments were conducted on a 250 or 500 g scale with a moderate
mixing and
temperatures approximately 40-45 C. If OCC (old corrugated containers) of 4%
consistency were
used as a fiber source, they were refined to 340 C.S.F. freeness before use.
[0071] UV-VIS absorbance for all examples was done as follows. After
the treatment, fiber
slurries were filtered thorough 355 micron sieves and filtrates were diluted
10 fold and analyzed
by UV-VIS spectrometry at 280 nm for soluble lignin content. Based on UV-VIS
absorbance
values % soluble lignin reductions were calculated.
[0072] Mutek charge was measured using a Mutek PCD-02 Particle
Charge Detector using
polydadmac 0.001 mol/L solution as a titrant. Filtrates were diluted 5 fold
before Mutek
measurements. Turbidity was measured by TD-300 from Hach and reported in FTU
units.
Example 1
[0073] Unbleached Kraft pulp (UBK) from a paper mill having a 4%
consistency was used for
the testing. 250 g of pulp samples were placed in a 45 C bath for thermal
equilibration and then
were treated with 1 lb/ton of six different polymers individually. These
polymers are Polymers A-
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F described above.
[0074] After the samples were stirred for an additional 10 min, they
were then removed from
the bath, cooled to room temperature, and filtered through a 355 micron sieve.
The filtrates were
assessed for the lignin content by UV-VIS measurements. % Lignin reduction was
calculated vs
samples with no treatment. The Lignin values and % lignin reductions are
summarized in the Table
1 set forth in FIG. 1.
[0075] The testing results indicate that specific polymers are more
efficient in lignin fixation
and removal from process water (filtrate). The list includes cationic (Polymer
A) and non-ionic
(Polymer B) polymers. Anionic polymers (Polymer E) or amphoteric polymers
(Polymer F) are
not efficient in lignin removal from process water.
Example 2
[0076] Dewatered OCC fiber and synthetic white water was used in the
testing. Cellulose fiber
and white water were combined to generate thick stock consistency close to 4%.
Thick stock
treatment testing was extended into 3 cycles in which 4% consistency stock was
treated with 1
lb/ton Polymer A and mixed for 30 min in every cycle and then filtered.
100771 The experiment was implemented in 2 ways: after each cycle
white water was isolated
form the thick stock cellulosic fiber by gravity filtration. Then filtered
white water was re-used in
successive steps with fresh pulp (this is represented as Treatment 1 line in
Table 2 of FIGS. 2A
and 2B) or the same fiber was reused in successive 3 steps (this is
represented as Treatment 2 line
in Table 2 of FIGS. 2A and 2B). All collected filtrates were analyzed for
lignin content. In either
case, a gradual reduction in soluble lignin content was observed with final
reductions of close to
70%.
100781 Finally, the testing was repeated in 1 step test where thick
stock was treated all at ones
with 3.0 lb/ton of Polymer A, then thick stock was filtered, and filtrate
analyzed for lignin content.
Lignin reductions were close to previous runs (this is represented as
Treatment 3 in Table 2 of
FIGS. 2A and 2B).
100791 These examples illustrate that lignin reductions happen in
similar manner regardless if
the fresh pulp is used in several steps for lignin fixation and removal or the
same pulp is used in
one or several steps of lignin removal. In a paper mill setting more gradual
(stepwise) reductions
in soluble lignin can be expected since "treated" process water can be
combined with "not-treated"
water for stock dilutions.
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Example 3
100801 Synthetic white water was used in this testing. Dewatered OCC
fiber was added to
white water to generate thick stock consistency close to 4%. Then, 500 g
samples were placed in
a 45 C bath for 30 min wherein some samples were not treated, others were
treated with 11b/ton
of Polymer A, 21b/ton of Polymer A, or with 3.0 lb/ton Polymer A. After 30
min, all samples were
removed from the bath, cooled to room temperature and filtered through a 355
micron sieve.
Filtrates were collected and analysed by UV-VIS at 280 nm for soluble lignin
determination.
Additionally, filtrates were analysed for COD content. The results are
summarized in Table 3 of
FIG. 3 and indicate that lignin reductions with polymer thick stock treatment
translate into
additional 12, 14 and 21 % reductions in COD content of white water. The
example illustrates that
effective lignin reductions with polymer treatment result in significant
reductions in COD content
of process water as well.
Example 4
100811 Thermomechanical (TMP) pulp of 4% consistency was used in the
testing below. The
TMP stock was split into three parts. The first part was not treated, the
second part was treated
with 11b/ton of Polymer D and the third part was treated with 11b/ton of
Polymer A. After the
treatment thick stock samples were placed in 45 C warm bath for 30 min. Then
the samples were
filtered, and filtrates were collected and used in drainage testing.
100821 The drainage activity was determined utilizing a Dynamic
Drainage Analyzer, test
equipment available from AB Akribi Kemikonsulter, Sundsvall, Sweden. The test
device applies
a 300 mbar vacuum to the bottom of the separation medium. The device
electronically measures
the time between the application of vacuum and the vacuum break point, i.e.
the time at which the
air/water interface passes through the thickening fiber mat. It reports this
value as the drainage
time. A lower drainage time is typical. 500 ml stock is added to the DDA and
the drainage test is
conducted at a total instrument vacuum of 300 mbar pressure.
100831 For drainage testing, dewatered TMP fiber (25% consistency)
was added to treated or
non-treated filtrates to generate fiber/water slurry of 0.7% consistency.
Drainage tests were
conducted with no drainage aid, with addition of Polymer D at 1 and 2 lb/ton
and with addition of
Polymer A at 1 and 2 lb/ton. Drainage results (in seconds) as well as %
Improvements (for polymer
efficiency) are summarized in the Table 4 and the graphs of FIGS. 4A-C. Figure
4B shows
drainage times with thick stock pre-treatments by Polymer D and Polymer A.
Figure 4C shows
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drainage polymer efficiency increase (%) with thick stock pre-treatments using
Polymer D and
Polymer A. % Improvement(s) were calculated based on difference between
drainage times of
non-treated sock and treated stock over the drainage time of non-treated stock
using the following
formula:
% Improvement = T2-T1 Ti
100%,
wherein Ti and T2 are drainage times without and with polymer aid,
respectively.
100841 Without thick stock pre-treatments, drainage times with
Polymer A and Polymer D
(43.21 and 44.65 sec, respectively) were very similar to the drainage time of
a sample without any
additive (46.93 sec). % Improvements (i.e. drainage aid efficiency) of both
polymers at 1 lb/ton
were quite low, 4.86% and 7.93% respectively.
100851 Thick stock pre-treatment with 1 lb/ton Polymer A followed by
addition of Polymer A
to thin stock as a drainage aid resulted in drainage time reductions from
43.21 sec down to 27.07
sec (11b/ton) and 20.95 sec (21b/ton). Overall drainage polymer efficiency
improved by 42-55%.
However, thick stock pre-treatment with 1 lb/ton Polymer D did not result in
drainage time
improvements. Drainage times changed from original 44.65 sec to 51.07 sec with
addition of
11b/ton Polymer D and 52.20 sec with 21b/ton. Drainage polymer efficiency
declined by 9-11%.
100861 This example illustrates that only specific polymers are
efficient in chemical efficiency
increase. In this case Polymer A was very efficient in drainage time
reductions and drainage
polymer efficiency increase.
Example 5
100871 Unbleached Kraft pulp (UBK) of 4% consistency from
containerboard mill was treated
with Polymer G at 0.25, 0.50, and 1.0 kg/ton. After polymer additions, 500 g
thick stock samples
were stirred for an additional 20 min at 45 C and then filtered. Filtrates
were analyzed for lignin
content and Mutek charge. Lignin and Mutek charge values (in ppm and gequ/l,
respectively) as
well as Lignin and Mutek charge reductions (in %) are summarized in Table 5 of
FIG. 5A. Data
indicate that Polymer G product is efficient in lignin reduction and lignin
reductions increase with
polymer load increase. Since lignin is a major contributor to Mutek charge,
effective lignin
removal from process water is accompanied with significant reductions in Mutek
charge as well.
100881 After lab evaluations lignin management technology was
applied in paper mill. In the
course of several days Polymer G was added in 1.0 kg/ton dosage to thick stock
of containerboard
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production process utilizing UBK pulp. Addition of Polymer G resulted in
lignin reductions up to
30%. Lignin reductions in its turn enabled machine speed increase and allowed
for the gradual
reduction in strength polymer feed up to 20%. The use of auxiliary anionic
polymer was fully
eliminated. As a strength polymer, a polyvinylamine based product along with
an auxiliary anionic
polymer can be used. Machine speed increased while maintaining paper strength
(SIFT)
requirements.
[0089] The graph of FIG. 5B shows the decline in soluble lignin in
top ply and base ply white
waters. Production consists of two production lines with two Fourdrinier
machines, PM #3 and
PM #4. In the course of the experiment, Polymer G was added to thick stock
consistency pulp of
the base ply before the refiner, whereas for the top ply the polymer treatment
was added to the
thick stock after refiner, right before machine chest. Soluble lignin
reduction trends indicate that
after refiner addition is more effective than that of before refiner. More
specifically, FIG. 5b shows
lignin reductions in white water collected from headbox areas of paper
machines producing base
and top ply for PM#4. This illustrates that even partial reduction in lignin
in process water with
application of lignin fixation polymer product(s) can result in significant
improvement in
papermaking: machine speed increase and strength additive efficiency increase.
Example 6
[0090] In this example, both lab tests and paper mill trials have
been carried out. The lab
testing was run using unbleached Kraft pulp (UBK). UBK pulp is produced by
batch cooking in
pulping section of integrated paper mill. Then it is used by two paper
machines PM#1 and PM#3
in the production of packaging paper.
[0091] In the lab testing, UKP pulp samples were treated with
Polymer G at 0.25, 0.50, and
1.0 kg/ton. After polymer additions 500 g thick stock samples were stirred for
an additional 20
min at 45 C and then filtered. Filtrates were analyzed for lignin content and
turbidity. Lignin and
turbidity values (in ppm, and FTU units) as well as Lignin and Turbidity
reductions (in %) are
summarized in Table 6a of FIG. 6A.
[0092] Lignin management technology was applied to a papermaking
process in a paper mill
as well. Polymer G was added to thick stock of two paper machines (PM#1 and
PM#3) at 0.9-1.2
kg/ton dosage. As a result of polymer treatments significant lignin reductions
in process waters of
both paper machines have been observed. Graph 6b of FIG. 6B shows lignin
reductions on one of
the paper machines (PM#1). More specifically, this graph includes a top line
representing lignin
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levels in process water in headbox of paper machine producing base ply and a
bottom line that
represents shows average lignin levels in process waters in headbox of paper
machine producing
top ply of two-ply paper production of PM#1. Average lignin levels were close
to 400 ppm before
the trial (before July) and they dropped to average of 150 ppm (from early
July) after addition of
Polymer G. Similar lignin reductions were observed on PM#3. Overall, Lignin
reductions were
close to 62% on PM#1 and 57% on PM#3.
[0093] Application of Polymer G to thick stock led to significant
reductions in lignin in process
water and that allowed for further improvements in papermaking process. Those
improvements
included significant reductions in Turbidity, 28 to 62% (see Table 6e of FIG.
6E). With lignin
reduction, water use in brown stock washing has been reduced by 20%. That
change resulted in
conductivity increase from 2800 to 3500 uS/cm and higher. This allows for use
of lesser amounts
of pitch/stickies contaminant control agents (Detac DC786C + Perform DC1871,
both Solenis
products) by 67% (see, e.g. Graph 6c of FIG. 6C) and for lesser amounts of
sizing agent (AKD
(alkyl ketene dimer)) by 25% (see, e.g. Graph 6d of FIG. 6D). Overall paper
machine runnability
improved. Major parameters on strength were in the desired specs.
100941 More specifically, graph 6c of FIG. 6C illustrates a decline
in use of pitch/stickies
control agents (Detac DC786C + Perform DC1871) with effective reduction in
lignin content of
process water. The top line indicates addition daily average dosages and grey
line indicates
monthly average values. Moreover, graph 6d of FIG. 6D illustrates a decline in
use of AKD (alkyl
ketene dimer) sizing agent with effective reduction in lignin content of
process water. The top line
indicates addition daily average dosages and grey line indicates monthly
average values. Table 6e
of FIG. 6E illustrates improvements observed in the pulping and papermaking
sections with the
application of lignin management Polymer G.
[0095] In addition to improvements in papermaking section,
significant advancements have
been achieved in pulping section. Reduction in water use in brown stock
washing resulted in
reduction black liquor volumes. That in its turn allowed for more wood chips
cooks and cellulose
production increase, see results in Table 6e. Average amounts of pulp produced
per day rose to
8.7%, with the highest value per day reaching to 12%. In addition, reductions
in brown stock
washing volumes resulted in 1.5% increase in % solids of black liquor. This
change resulted in
improvements in black liquor evaporators efficiency, steam production increase
(16.4%) and oil
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consumption reductions (25%). Lignin management in papermaking section allowed
for cellulosic
pulp production increase, energy savings and fresh/condensed water usage
reduction.
100961 While at least one exemplary embodiment has been presented in
the foregoing detailed
description, it should be appreciated that a vast number of variations exist.
It should also be
appreciated that the exemplary embodiment or exemplary embodiments are only
examples, and
are not intended to limit the scope, applicability, or configuration in any
way. Rather, the foregoing
detailed description will provide those skilled in the art with a convenient
road map for
implementing an exemplary embodiment. It being understood that various changes
may be made
in the function and arrangement of elements described in an exemplary
embodiment without
departing from the scope as set forth in the appended claims.
100971 Moreover, all individual components, method steps,
conditions, physical properties,
etc. that are described above are hereby expressly contemplated for use
together in one or more
non-limiting embodiments even though they may not be described together above.
In other words,
all combinations of the aforementioned components, method steps, conditions,
physical properties,
etc. are hereby expressly contemplated for use in various non-limiting
embodiments.
23
CA 03196967 2023- 4- 28
