U.S. patent application number 16/748830 was filed with the patent office on 2020-07-30 for method and system for dewatering and controlling foam in pulp and paper processes.
This patent application is currently assigned to Buckman Laboratories International, Inc.. The applicant listed for this patent is Buckman Laboratories International, Inc.. Invention is credited to Paul C. Brister, Philip M. Hoekstra.
Application Number | 20200240078 16/748830 |
Document ID | 20200240078 / US20200240078 |
Family ID | 1000004627135 |
Filed Date | 2020-07-30 |
Patent Application | download [pdf] |
![](/patent/app/20200240078/US20200240078A1-20200730-D00001.png)
United States Patent
Application |
20200240078 |
Kind Code |
A1 |
Hoekstra; Philip M. ; et
al. |
July 30, 2020 |
Method And System For Dewatering And Controlling Foam In Pulp And
Paper Processes
Abstract
Methods and systems are provided for dewatering an aqueous
cellulosic pulp slurry or mat of cellulosic fibers or sludge. The
method includes adding at least one anionic surfactant and at least
one amide of a carboxylic acid to cellulose containing material to
form a treated material and then dewatering the material. Besides
effective dewatering, the present invention also provides foam
control such as, but not limited to, the suppression of foam. Pulp
products containing the treatment compounds are also described.
Inventors: |
Hoekstra; Philip M.;
(Memphis, TN) ; Brister; Paul C.; (Memphis,
TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Buckman Laboratories International, Inc. |
Memphis |
TN |
US |
|
|
Assignee: |
Buckman Laboratories International,
Inc.
Memphis
TN
|
Family ID: |
1000004627135 |
Appl. No.: |
16/748830 |
Filed: |
January 22, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62797416 |
Jan 28, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 11/20 20130101;
D21C 9/18 20130101; D21H 11/14 20130101; D21C 9/1005 20130101 |
International
Class: |
D21C 9/18 20060101
D21C009/18; D21H 11/20 20060101 D21H011/20; D21H 11/14 20060101
D21H011/14; D21C 9/10 20060101 D21C009/10 |
Claims
1. A method for dewatering a cellulose-containing material, said
method comprising: adding at least one anionic surfactant and at
least one amide of a carboxylic acid to said cellulose-containing
material to form a treated cellulose-containing material; and
dewatering said treated cellulose-containing material to provide a
dewatered cellulose-containing material.
2. The method of claim 1, wherein said cellulose-containing
material is an aqueous cellulosic pulp slurry.
3. The method of claim 1, wherein said cellulose-containing
material is a mat of cellulosic fibers.
4. The method of claim 1, wherein said cellulose-containing
material is a sludge from a paper and pulp manufacturing
process.
5. The method of claim 1, wherein said anionic surfactant and said
amide of a carboxylic acid are added together to said
cellulose-containing material.
6. The method of claim 1, wherein said anionic surfactant and said
amide of a carboxylic acid are separately added to said
cellulose-containing material.
7. The method of claim 1, wherein the anionic surfactant is an
organic anionic surfactant.
8. The method of claim 1, wherein said amide of a carboxylic acid
comprises a dimethylamide of a fatty acid.
9. The method of claim 1, wherein said amide of a carboxylic acid
comprises a dimethylamide of a fatty acid having 14 to 18 carbon
atoms.
10. The method of claim 1, wherein said cellulose-containing
material is an aqueous cellulosic pulp slurry, and wherein said
method further comprising bleaching the aqueous cellulosic pulp
slurry after pulp forming and before the adding of the anionic
surfactant and said amide of a carboxylic acid.
11. The method of claim 1, wherein said cellulose-containing
material is an aqueous cellulosic pulp slurry, and wherein said
method further comprising thermally drying said
cellulose-containing material that is dewatered to form market
pulp.
12. The method of claim 1, wherein the anionic surfactant is a
sulfate surfactant, a sulfonate surfactant, a sulfosuccinate
surfactant, or any combinations thereof.
13. The method of claim 1, wherein the anionic surfactant is an
alcohol sulfate, an alcohol alkoxy sulfate, a sulfonate, a dialkyl
sulfosuccinate, a sulfosuccinic acid ester with an ethoxylated
alcohol, or a soluble or dispersible salt thereof, or any
combinations thereof.
14. The method of claim 1, said method further comprising bleaching
said cellulose-containing material before the adding of the at
least one anionic surfactant and the at least one amide of a
carboxylic acid.
15. The method of claim 1, said method further comprising adding at
least one enzyme to said cellulose-containing material before said
dewatering step.
16. The method of claim 1, wherein said amide of a carboxylic acid
is added in an amount to control foam height during said
dewatering.
17. The method of claim 1, wherein the at least one anionic
surfactant and the at least one amide of a carboxylic acid are
added to the pulp in a weight ratio of from about 90:10 to about
10:90.
18. The method of claim 1, wherein the anionic surfactant is added
to the pulp in an amount of from about 0.1 lb./ton dry fiber to
about 10 lb./ton dry fiber, and the amide of a carboxylic acid is
added to the pulp in an amount of from about 0.001 lb./ton dry
fiber to about 2 lb./ton dry fiber.
19. The method of claim 1, wherein said cellulose-containing
material is formed from hardwood chips, softwood chips, recycled
paper fiber, or any combinations thereof.
20. The method of claim 1, wherein the combination of treating the
pulp with the at least one anionic surfactant and at least one
amide of a carboxylic acid before said dewatering is effective to
provide at least one of the following: (i) increased dewatering of
a pulp slurry to a value which is at least 7.5% times greater than
the amount of water removed obtained without any treatment in the
pulp; (ii) reduced foam height during said dewatering compared to
foam height occurring with using the same anionic surfactant in the
absence of said amide of a carboxylic acid.
21. The method of claim 1, wherein said method is effective for
increasing obtained water removal to a value which is at least five
times greater than the water removal obtained without any treatment
of the pulp.
22. A dewatered cellulosic containing material dewatered by the
method of claim 1, said dewatered cellulosic containing material
comprising dewatered cellulosic containing material, said anionic
surfactant and said amide of a carboxylic acid.
23. The dewatered cellulosic containing material of claim 22,
wherein said dewatered cellulosic containing material is dewatered
pulp or dewatered sludge.
Description
BACKGROUND OF THE INVENTION
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of prior U.S. Provisional Patent Application No. 62/797,416,
filed Jan. 28, 2019, which is incorporated in its entirety by
reference herein.
[0002] The present invention is useful in the pulp and paper
industry and processes utilized in pulp and/or paper processes,
including, but not limited to, processes used in the production of
pulp, market pulp, and paper and byproducts of these processes
(e.g., sludge from the pulp and paper process). More particularly,
methods and systems are provided for dewatering, such as improving
drainage of products such as pulp or pulp slurries, paper, or any
surface that desires removal of water, whether a particulate
surface or mat. The dewatering effect can be achieved without
causing formation of an excessive amount of foam.
[0003] In the pulp making industry, cellulose-containing feed
material has been defibrated chemically, mechanically, or both, and
then typically is washed and at least partly dewatered after such
operations. In pulping processes in which the pulp is chemically
treated, such as by chemical digestion, bleaching, or other
chemical treatments, dewatering can be used to drain water and
separate free chemical from the fibers. Some pulp mills may be
integrated with a paper making plant, wherein the dewatering of the
product pulp may be limited such that slurry pulp or wet laid pulp
can be directly advanced to a papermaking machine at the same
production site. Other pulp mills produce market pulp in
non-integrated production operations. Market pulp can be a pulp
product which has been significantly dewatered in the final stages
of pulp processing. Market pulp further may be formed into bales or
rolls of dewatered pulp. The market pulp can be transported to
other locations for later use.
[0004] A particular process for producing market pulp which uses
diverse ionic compounds before pulp drying is described in U.S.
Pat. No. 8,916,024. According to the process of U.S. Pat. No.
8,916,024, pulp is treated with a combination of cationic and
anionic surfactants before drying, and more particularly, the
treatment involves treating pulp with a combination of at least one
cationic polymer and at least one anionic polymer effective to form
a polyelectrolyte complex in the treated pulp. U.S. Pat. No.
6,706,144 shows a method of dewatering an aqueous cellulosic pulp
slurry, which may be a market pulp slurry, wherein a mixture of one
or more nontoxic surfactants and one or more anionic surfactants is
added to the slurry.
[0005] While the chemicals used to enhance dewatering can be
effective, certain chemicals and their use in the process of
dewatering can generate excessive amounts of foaming. This is
particularly a problem with the use of certain surfactants. While
conventional defoamer agents have been tried, often times, a
trade-off occurs. The addition of a defoamer provides added cost.
In other cases, while the foam can be controlled, the enhanced
dewatering effects are reduced, thus a deleterious effect on the
dewatering of the pulp and other products. With the present
invention, there was an effort to design a method and system that
can maintain the enhanced dewatering effects of the pulp and/or
other products and yet control or suppress the undesired foam
formation. Further, a method and system that can have the defoamer
agent actually further enhance dewatering, besides controlling
foaming would be most desired. The present invention can achieve
this as described herein. Such an invention permits an increased
rate at which pulp dewatering can be accomplished in a pulp mill
and can significantly affect the overall line speed and production
capacity of the pulp mill or similar production facility.
SUMMARY OF THE PRESENT INVENTION
[0006] A feature of the present invention is to provide a method
for dewatering a cellulose-containing material.
[0007] A further feature of the present invention to provide a
method that improves one or more properties of a dewatering
process, such as improving dewatering performance and
efficiency.
[0008] Another feature of the present invention is to provide a
method that enhances dewatering of a cellulose containing material,
such as pulp, and further achieves foam suppression or foam control
during the dewatering process.
[0009] An additional feature of the present invention is to provide
a method where the foam can be controlled without negatively
affecting the enhanced dewatering effects. A further feature is to
provide a method and system that can maintain the enhanced
dewatering effects of the pulp and/or other products and yet
control or suppress the undesired foam formation.
[0010] Another feature is to provide a method and system that can
have the defoamer agent actually further enhance dewatering,
besides controlling foaming.
[0011] Additional features and advantages of the present invention
will be set forth in part in the description that follows, and in
part will be apparent from the description, or may be learned by
practice of the present invention. The objectives and other
advantages of the present invention will be realized and attained
by means of the elements and combinations particularly pointed out
in the description and appended claims.
[0012] To achieve these and other advantages, and in accordance
with the purposes of the present invention, as embodied and broadly
described herein, the present invention relates, in one embodiment,
to a method for dewatering a cellulose-containing material. The
method includes adding at least one anionic surfactant and at least
one amide of a carboxylic acid to a cellulose-containing material
to form a treated cellulose-containing material and the method
further includes dewatering the treated cellulose-containing
material to provide a dewatered cellulose-containing material. The
cellulose-containing material can be in the form of an aqueous
cellulosic pulp slurry or can be in the form of a mat of cellulosic
fibers, or can be in the form of a sludge from a paper and pulp
manufacturing process.
[0013] The present invention further relates to a method to dewater
a cellulose-containing material and at the same time control or
suppress foam or foam formation. The method includes adding at
least one anionic surfactant and at least one amide of a carboxylic
acid to a cellulose-containing material to form a treated
cellulose-containing material and the method further includes
dewatering the treated cellulose-containing material to provide a
dewatered cellulose-containing material, wherein the at least one
anionic surfactant and at least one amide of a carboxylic acid are
each present in effective amounts to improve dewatering properties
and improve in foam control and/or suppression.
[0014] The present invention further relates to a system for
producing pulp or market pulp comprising a supply of cellulosic
fibers; at least one pulp forming unit for forming pulp from the
cellulosic fibers; at least one feeding device for feeding at least
one anionic surfactant, to the pulp; at least one feeding device
for feeding at least one amide of a carboxylic acid to the pulp; a
dewatering device for mechanically removing water from the pulp;
and optionally a dryer for thermally removing water from the pulp
to provide pulp or market pulp.
[0015] The present invention further relates to a dewatered
cellulosic containing material containing a dewatered cellulosic
containing material, at least one anionic surfactant, and at least
one amide of a carboxylic acid. The dewatered cellulosic containing
material can be a dewatered pulp or dewatered sludge. In the
dewatered cellulosic containing material, the anionic surfactant
can be present in an amount of from 1 ppm to 1,000 ppm and the
amide of a carboxylic acid can be present in an amount of from 1
ppm to 1,000 ppm.
[0016] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are intended to provide a further
explanation of the present invention, as claimed.
[0017] The accompanying drawings, which are incorporated in and
constitute a part of this application, illustrate some of the
embodiments of the present invention and together with the
description, serve to explain the principles of the present
invention.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a graph showing foam height vs. time (seconds) for
a variety of treatments utilizing the present invention and one
comparative example.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0019] The present invention relates to a method for dewatering a
cellulose-containing material.
[0020] The present invention further relates to method for foam
control and/or foam suppression during a dewatering process of
cellulose-containing material and/or other part of a process in a
paper making or pulp making process (e.g., a step or part of a
process in a paper making or pulp making process wherein foam
control or foam suppression and/or drainage is desired).
[0021] The method of the present invention has the unique ability
to provide dual property improvements, namely, an improvement in
dewatering performance and an improvement in foam control and/or
foam suppression.
[0022] For instance, the method of the present invention has the
unique ability to provide dual property improvements, namely, an
improvement in dewatering performance and an improvement in foam
control and/or foam suppression, wherein each component used can
actually increase both properties collectively. It was unexpected
to discover that a particular class of foam-controlling additive,
when combined with an anionic surfactant(s), can achieve the same
degree or about the same degree (e.g., within 10%) of dewatering
improvement without the high amount of foam that usually forms or
occurs with the use of anionic surfactants. Thus, with the present
invention, the addition of anionic surfactant and an amide of a
carboxylic acid controls the foam problem while at the same time
not interfering with the desired dewatering effect.
[0023] The present invention includes a method that comprises,
consists essentially of, consists of, or includes adding at least
one anionic surfactant and at least one amide of a carboxylic acid
to a cellulose-containing material to form a treated
cellulose-containing material.
[0024] The method can further include dewatering the treated
cellulose-containing material to provide a dewatered
cellulose-containing material (or dewatered treated
cellulose-containing material).
[0025] For purposes of the present invention, the
cellulose-containing material can comprise, consist essentially of,
consists of, or be an aqueous cellulosic pulp slurry. For purposes
of the present invention, the cellulose-containing material can be
or include a mat of cellulosic fibers. For purposes of the present
invention, the cellulose-containing material can be or include a
sludge from a paper and pulp manufacturing process.
[0026] Regarding the adding of the anionic surfactant and the amide
of a carboxylic acid, the anionic surfactant and the amide of a
carboxylic acid can be added together as a pre-combined mixture or
can be added as separate components or compositions or streams to
the cellulose-containing material or tank or container holding the
cellulose containing material or added to an aqueous stream or
other industrial stream that contacts the cellulose containing
material. Agitation of the cellulose-containing material can
optionally occur before, during, and/or after the addition of the
anionic surfactant and the amide of a carboxylic acid.
[0027] As an option, the anionic surfactant and the amide of a
carboxylic acid can be added separately to the cellulose-containing
material. The separate additions can be at the same time of each
other, or at about the same time (e.g., within 15 seconds of each
other), or the anionic surfactant can be added before and/or after
the amide of a carboxylic acid, and/or the amide of the carboxylic
acid can be added before and/or after the anionic surfactant during
the method of the present invention. The time of such additions can
be within seconds or minutes of each other (e.g., within 15
minutes, within 10 minutes, within 5 minutes, within 1 minute or
other times more than or less than any of these time amounts).
[0028] Regarding the anionic surfactant, one or more than one type
of anionic surfactant can be used. The anionic surfactant can be an
organic anionic surfactant(s).
[0029] The anionic surfactant(s) can be one or more anionic
compounds and/or can be one or more anionic polymers. Examples
include, but are not limited to, an alcohol sulfate, an alcohol
alkoxy sulfate, a sulfonate, a sulfosuccinate, a sulfosuccinic acid
ester with an ethoxylated alcohol, and any soluble or dispersible
salts thereof, or any combinations thereof. A sulfonate refers to a
salt or ester of a sulfonic acid. A sulfosuccinate refers to a
sulfonate derivative of succinate (e.g., a salt or ester of
sulfosuccinic acid). For salts thereof, the counterion can be a
metal ion, such as an alkali metal (e.g., sodium, potassium). More
specific examples include, but are not limited to, a fatty alcohol
sulfate (e.g., C12-18 fatty alcohol sulfate), an alkyl alcohol
sulfate (e.g., C10-C16 alkyl alcohol sulfate), an ethoxylated
alcohol sulfate (e.g., ethoxylated C4-C12 alcohol sulfate), a
sulfonated fatty acid alkyl ester, an olefin sulfonate, a paraffin
sulfonate, an alkylbenzylsulfonate, and a dialkyl sulfosuccinate.
Additional examples include dodecyl alcohol sulfate, hexadecyl
alcohol sulfate, dodecyl ethoxy sulfate, tetradecyl ethoxy sulfate,
decylbenzene sulfonate, tetradecyl benzene sulfonate, tetradecyl
sulfonate, octadecyl sulfonate, 3-hydroxy-1-hexadecane sulfonate,
2-hexadecene-1-sulfonate, dioctylsulfosuccinate sodium salt, or
others. The anionic surfactant can be an anionic surfactant, which
is a sulfate surfactant, a sulfonate surfactant, a sulfosuccinate
surfactant, or any combinations thereof. To avoid any doubt, the
anionic surfactant is a separate component from the amide of a
carboxylic acid.
[0030] As an option, at least one anionic surfactant can be added
to the pulp in the processes of the present invention in an amount
from about 0.1 lb. to about 10 pounds (lb.) anionic surfactant/ton
dry fiber, or from about 0.2 to about 8 lb. charged compound/ton
dry fiber, or from about 0.3 to about 4 lb. anionic surfactant/ton
dry fiber, or from about 0.5 to about 3 lb. anionic surfactant/ton
dry fiber (on a solids/solids basis).
[0031] Regarding the amide of a carboxylic acid, one or more types
of an amide of a carboxylic acid can be used. For purposes of the
present invention, the amide of a carboxylic acid can be a
carboxylic acid amide(s). Any carboxylic acid containing from 12-18
carbon atoms is suitable. The amide of a carboxylic acid can be an
amide of a straight chain carboxylic acid. For instance,
N,N-dimethylamides of carboxylic acids can be prepared from
straight chain carboxylic acids containing from 12-18 carbon atoms.
The carboxylic acid part can be further characterized by having at
least one carbon to carbon double bond. Acids can include: oleic,
linoleic, linolenic, ricinoleic, and mixtures thereof. Also
suitable are mixed acids such as tall, castor, corn, cottonseed,
linseed, olive, peanut, rapeseed, safflower, sesame, and/or soybean
oils. A mixture of carboxylic acids commercially available as a
tall oil fatty acid is UNITOL ACD SPECIAL.
[0032] The amide of a carboxylic acid can be at least one compound
of formula I:
R.sub.3C(O)--N(R.sub.1)(R.sub.2) (I)
wherein R.sub.1 is a hydrogen or a substituted or unsubstituted
C.sub.1-C.sub.12 alkyl (such as a C.sub.1-C.sub.6 alkyl) group;
R.sub.2 is a hydrogen or a substituted or unsubstituted
C.sub.1-C.sub.12 alkyl (such as a C.sub.1-C.sub.6 alkyl) group; and
R.sub.3C(O)-- is a substituted or unsubstituted fatty acid residue
of 6 to 22 carbon atoms such as 8 to 12 carbon atoms.
[0033] The fatty acid residue, R.sub.3C(O)--, of compound I,
defined above, may be a substituted or unsubstituted residue of a
fatty acid which occurs in a vegetable oil. The vegetable oil may
be selected from tall oil, palm oil, soybean oil, cottonseed oil,
coconut oil, corn oil, peanut oil, canola oil, safflower oil,
sunflower oil, babassu oil, castor oil, linseed oil, olive oil, and
tung oil.
[0034] In general, the dialkylamides of any carboxylic acid having
8 to 22 carbon atoms can be used in the methods of the present
invention. Examples include those based on fatty acids having 18
carbon atoms such as stearic, oleic, linoleic, linolenic and
ricinolenic acid. An example of a dialkyl amide is N,N-dimethyl
oleamide.
[0035] A further example of an amide of a carboxylic acid is
carboxylic acid dialkyl amides, and more particularly dimethyl
amides, dibutyl amides, dioctyl amides, or di-2-ethylhexyl amides.
Specific examples include dialkyl amides, such as, capric acid
dimethyl amide, capric acid dibutyl amide, capric acid dioctyl
amide, capric acid di-2-ethylhexyl amide, caprylic acid dimethyl
amide, caprylic acid dibutyl amide, caprylic acid dioctyl amide,
caprylic acid di-2-ethylhexyl amide, capronic acid dimethyl amide,
capronic acid dibutyl amide, capronic acid di-2-ethylhexyl amide,
lauric acid dimethyl amide, lauric acid dibutyl amide, lauric acid
di-2-ethylhexyl amide, lactic acid dimethyl amide, lactic acid
dibutyl amide, and/or lactic acid di-2-ethylhexyl amide and/or
their blends.
[0036] The amide of a carboxylic acid can comprise, consists
essentially of, consist of, or be a dimethylamide of a fatty acid.
The dimethylamide of a fatty acid can have from 4 to 22 carbon
atoms, such as 14 to 18 carbon atoms.
[0037] The amide of the carboxylic acid can be added to the
cellulose containing material in an amount from about 0.001 to
about 2 pounds (lb.) per ton dry fiber, or from about 0.01 to about
1.5 lb./ton dry fiber, or from about 0.1 to about 1 lb./ton dry
fiber, or other amounts.
[0038] The amount of the amide of the carboxylic acid added
generally is an amount that causes at least some foam control or
suppression during the dewatering process. For instance, this can
be measured, as shown in the example, by a foam height measurement
test. With the present invention, the maximum foam height achieved
is reduced, for instance by at least 10 percent in height, as
compared to when no amide of carboxylic acid is present or compared
to when no defoaming agent is present at all, or compared to when
no amide of carboxylic acid is present but at least one anionic
surfactant is present.
[0039] As an option, no other class of defoaming agent is used in
the method of the present invention.
[0040] As an option, at least one anionic surfactant and at least
one amide of carboxylic acid can be added to the cellulose
containing material in a total amount of from about 0.2 lb./ton dry
fiber to about 12 lb./ton dry fiber, or from about 0.4 to about 10
lb./ton dry fiber, or from about 0.6 to about 8 lb./ton dry fiber,
or from about 1 to about 6 lb./ton dry fiber (on a solids/solids
basis), or other values.
[0041] As an option, at least one anionic surfactant and at least
one amide of a carboxylic acid can be added to the cellulose
containing material in a weight amount of from about 95 wt %:5 wt %
(anionic surfactant: amide of carboxylic acid) to about 5 wt %:95
wt %, such as 90:10 to 10:90, or 80:20 to 20:80, or 70:30 to 30:70
(each number in wt %). The amide of carboxylic acid can be present
in an amount of from about 50 wt % to about 90 wt %. The anionic
surfactant can be present in an amount of from about 50 wt % to 10
wt %. For each of these wt % provided here, the wt % are based on
the total weight of both components present.
[0042] The anionic surfactant and amide of carboxylic acid, for
example, can be added to the cellulose containing material, such as
pulp, sequentially by separate additions thereof at different
process locations or at different times at the same process
location, or they can be added concurrently at least in part at the
same process location (e.g., as separate feeds or as a
pre-mixture). As an option, pulp or market pulp can be produced by
sequentially adding at least about 80% up to 100% by weight of the
total added amount of the anionic surfactant after addition of the
at least one amide of carboxylic acid to the pulp before dewatering
the pulp. In such an option, the amide of carboxylic acid is given
the opportunity to interact first with the pulp fibers before
interactions are made with the anionic surfactant. The addition of
the at least one anionic surfactant and at least one amide of
carboxylic acid in this sequence can magnify the enhancements in
the foam control and dewatering performance that can be achieved.
As another option, at least a portion or all of the anionic
surfactant can be added to the pulp before the amide of carboxylic
acid is added to the pulp. With the present invention, compared to
pulp drainage seen without the addition of any anionic surfactant
or amide of carboxylic acid, or using just the anionic surfactant
alone or using the amide of carboxylic acid alone, to the pulp,
pulp drainage performance in combination with foam control in the
production of pulp or market pulp can be significantly increased,
such as by a factor of one, two, or three or more with processes of
the present invention. Further, as compared to use of only an
anionic surfactant alone or the use of an amide of carboxylic acid
alone, to treat the pulp, drainage efficiencies along with foam
control can be significantly increased, such as by about 10% to
about 200%, or other increases, by the combined addition of at
least one anionic surfactant and at least one amide of carboxylic
acid to the pulp. In addition, drainage rates with foam control can
be achieved that exceed the sum of the individual rates obtained
from use of the anionic surfactant alone or the amide of carboxylic
acid individually to treat a pulp. For instance, better drainage
and reduced foaming in the wire section of the pulp dryer can lead
to reduced moisture of pulp in the press section, and as a result,
steam consumption in the drying section can be significantly
reduced, which can provide energy savings. Further, improvements of
pulp dewatering and foam control provided by treatment of digested
pulp with the present invention prior to pulp drying can allow for
faster pulp throughout rates or speeds in the pulp mill, whereby
the productivity of the pulp mill can be increased. Free drainage
properties of the pulps treated with the present invention before
pulp drying can demonstrate good correlations with water retention
properties, such as in terms of water retention values or WRV, of
the treated pulps, which indicates that the treatment can yield
reliable nonrandomized results.
[0043] With the present invention, a lower amount of anionic
surfactant than conventionally used for a dewatering process, can
be utilized in view of the use of at least one amide of carboxylic
acid. For instance, the amount of anionic surfactant used can be
reduced by at least 10 wt %, at least 25 wt %, at least 50 wt % or
more and yet achieve the same or substantially the same (e.g.
within 15%, or within 10%, or within 5%, or within 1%) of
dewatering properties of the cellulose containing material.
[0044] In the method of the present invention, when the cellulose
containing material is an aqueous cellulosic pulp slurry, the
method can include a step of bleaching the aqueous cellulosic pulp
slurry after pulp forming and before the adding of the anionic
surfactant and the amide of a carboxylic acid.
[0045] In addition, or separately, in the method of the present
invention, when the cellulose containing material is an aqueous
cellulosic pulp slurry, the method can include a step of thermally
drying the dewatered cellulose-containing material. This step can
form a market pulp.
[0046] As a further example, the present invention can be utilized
in the production of market pulp. The pulp during the production is
treated with one or more anionic surfactants and with one or more
amide of a carboxylic acid to improve pulp dewatering performance
and efficiency thereof and/or foam control and/or foam suppression
and/or other properties. As used herein, "market pulp" refers to
mechanically dewatered pulps which are thermally dried. The market
pulp provides a dry form of product material which has useful
storage stability and can be more easily shipped and handled than
bulkier aqueous forms of pulp product. The market pulp can be
stored, transported, or both for subsequent use as a process
material used in other production processes. The market pulp
optionally can be securely wrapped as a unitized product for
shipping or transport for further processing, such as
papermaking.
[0047] The present invention further relates to a dewatered
cellulosic containing material dewatered by the method of present
invention. Due to the process that the cellulosic containing
material is subjected to, a unique cellulosic containing material
can be obtained.
[0048] In more detail, the present invention provides a dewatered
cellulosic containing material comprising, consisting essentially
of, consisting of, or is a dewatered cellulosic containing material
with the anionic surfactant and the amide of a carboxylic acid
present. The amount of the anionic surfactant and amide of the
carboxylic acid can be residue amounts or other amounts. The
dewatered cellulosic containing material can be a dewatered pulp or
dewatered cellulosic containing mat or dewatered market pulp or
dewatered sludge. The dewatered cellulosic containing material can
comprise from about 1 ppm to 1,000 ppm anionic surfactant(s) (e.g.,
from 10 ppm to 1,000 ppm, from 25 ppm to 1,000 ppm, from 50 ppm to
1,000 ppm, from 100 ppm to 1,000 ppm, from 100 ppm to 500 ppm, from
250 ppm to 500 ppm) and from about 1 ppm to 1,000 ppm of an
amide(s) of a carboxylic acid (e.g., from 10 ppm to 1,000 ppm, from
25 ppm to 1,000 ppm, from 50 ppm to 1,000 ppm, from 100 ppm to
1,000 ppm, from 100 ppm to 500 ppm, from 250 ppm to 500 ppm) and
the balance can be cellulosic materials (such as cellulosic fibers
or pulp), and these amounts can be based on dry weight of the
fibers or wet weight after dewatering and/or after dewatering and
drying. The dewatered cellulosic containing material can comprise,
for example, from about 0.001 to about 5 pounds (lb.) anionic
surfactant/ton dry fiber, or from about 0.01 to about 3 lb. anionic
surfactant/ton dry fiber, or from about 0.1 to about 2 lb. anionic
surfactant/ton dry fiber, or from about 0.2 to about 1 lb. anionic
surfactant/ton dry fiber (on a solids/solids basis), and the amide
of carboxylic acid can be contained in the cellulosic containing
material in an amount of from about 0.000001 lb. to about 1 lb./ton
dry fiber or from about 0.00001 lb. to about 0.1 lb./ton dry
fiber.
[0049] With the present invention, in general, these treatment
additives (i.e., anionic surfactant and the amide of carboxylic
acid) impact the dewatering performance (including foam control
and/or suppression) in significant and beneficial ways that would
not be expected from the use of either the anionic surfactant alone
or the amide of carboxylic acid alone, and in some options may
exceed additive expected effects from each individual component.
The combined treatment of the cellulose containing material with
the anionic surfactant and amide of carboxylic acid can provide a
synergistic effect on water removal (including foam control and/or
suppression) which is much better than either treatment alone and
much better than the additive effect expected.
[0050] It has been observed that the high basis weight of some pulp
sheets on a pulp dryer, for example, can be an impediment to good
drainage. It has been found that significant improvements in
dewatering performance at a pulp dryer can be provided in the
production of pulp or market pulp by treatment of pulps after
digestion or other mode of defibration, and any bleaching, and
before pulp drying, with the anionic surfactant and amide of
carboxylic acid used in combined treatment of pulps. Treatment of
the pulp prior to the pulp dryer with the combination of the
anionic surfactant and with the amide of carboxylic acid, for
example, can increase the free drainage rate of the pulp while
controlling foam and/or suppressing foam. Increasing the free
drainage rate of the pulp and controlling foam makes it feasible to
increase the production speed and capacity of the process for
producing market pulp. As an option, the pulp treatment methods and
systems of the present invention are not part of, nor integrated
with, a paper making machine.
[0051] As an option, at least one anionic surfactant and at least
one amide of carboxylic acid are added to treat the pulp before the
pulp is dewatered and dried in a pulp dryer. As an option, the
amide of carboxylic acid can be added to the pulp at a feed line
and the anionic surfactant can be added at a separate or same feed
line at the inlet side of the pulp dryer. The addition of at least
one anionic surfactant and at least one amide of carboxylic acid to
the pulp before the dryer can improve dewatering performance at the
dryer. As an option, for bleached pulp, at least one anionic
surfactant and at least one amide of carboxylic acid can be added
to the pulp anywhere after the bleach plant and before the dryer.
As another option, for unbleached pulp, at least one anionic
surfactant and at least one amide of carboxylic acid can be added
to the pulp anywhere after the digester and before the dryer. As an
option, the anionic surfactant is added to the pulp no earlier than
the addition of the amide of carboxylic acid to the pulp. As an
option, the anionic surfactant is added to the pulp at times which
can partially overlap with the addition times of the amide of
carboxylic acid. As an option, all amounts of the amide of
carboxylic acid are added to the pulp before the addition of all
amounts of the anionic surfactant to the pulp. As an option, about
80% to 100%, or from about 85% to 100%, or from about 90% to 100%,
or from about 95% to 100% by weight, of the total weight amount of
amide of carboxylic acid, is added to the pulp prior to the
earliest adding of the anionic surfactant to the pulp.
[0052] As an option, one or more enzymes can be additionally added
in the methods of the present invention to the cellulose containing
material. The enzyme can include, for example, an enzyme having
cellulolytic activity, hemi-cellulolytic activity, pectinolytic
activity, or glycosidasic activity. The enzyme can be a hydrolytic
enzyme which has activity that affects the hydrolysis of fiber
(e.g., hydrolytic activity), such as to accelerate the hydrolysis
of a chemical bond. The enzyme can be, for example, cellulase,
hemicellulase, lipase, pectinase, cellobiase, xylanase, protease,
mannanase, .beta.-glucanase, carboxymethylcellulase (CMCase),
amylase, glucosidase, galactosidase, laccase, or any combinations
thereof. A single type of enzyme or a combination of two or more
different types of enzymes can be used jointly with the anionic
surfactant(s). A cellulolytic enzyme composition can contain, for
example, from about 5% by weight to about 20% by weight enzyme.
These enzyme compositions can further contain, for example,
polyethylene glycol, hexylene glycol, polyvinylpyrrolidone,
tetrahydrofuryl alcohol, glycerine, and/or water, and/or other
conventional enzyme composition additives, as for example,
described in U.S. Pat. No. 5,356,800, which is incorporated herein
in its entirety by reference. If enzyme substrates are present with
dry powder forms of the enzymes, the substrates should not
adversely interact with or interfere with the pulp treatment or
other papermaking processes.
[0053] The enzyme can be added in an amount, for example, of from
about 0.0001% by weight to about 5% by weight enzyme based on the
dry weight of the pulp, or from about 0.0005% by weight to about
4.5% by weight, or from about 0.001% to about 4% by weight, or from
about 0.005% to about 3.5% by weight, or from about 0.01% to about
3% by weight, or from about 0.05% by weight to about 2.75% by
weight, or from about 0.1% by weight to about 2.5% by weight, or
from about 0.2% by weight to about 1.5% by weight, or from about
0.001% to about 0.1% by weight, or from about 0.005% to about 0.5%
by weight enzyme based on dry weight of the pulp, though other
amounts can be used.
[0054] As indicated, the combination of treating the pulp with at
least one anionic surfactant and at least one enzyme before
dewatering beneficially influences the drainage and dewatering
behavior of the treated pulps and further provides the control of
foam formation and/or provides foam suppression.
[0055] With the present invention, the combination of treating the
pulp with the at least one anionic surfactant and at least one
amide of a carboxylic acid before said dewatering can be effective
to provide at least one (or two or three or all) of the following:
[0056] (i) increased pulp free drainage (g/90 sec) to a value which
is at least 7.5% greater than free drainage value obtained without
any treatment in the pulp; [0057] (ii) reduced foam height during
said dewatering compared to foam height occurring with using the
same anionic surfactant in the absence of said amide of a
carboxylic acid. [0058] (iii) increased removal of water from the
cellulose fibers in the pressing process that occurs after
drainage. [0059] (iv) accelerated removal of water from the
cellulose fibers in a heated drying process that is used to produce
a dry pulp sheet.
[0060] With the present invention, the method can be effective for
increasing obtained free drainage to a value which is at least two
times, at least three times, at least four times, or at least five
times greater than free drainage value obtained without any
treatment of the pulp. Water removal measurements can be obtained
using a Mutek DFR-05 drainage/retention tester. The Mutek DFR-05
drainage freeness retention simulates the retention and drainage
conditions prevailing in a pulp or paper machine.
[0061] These and/or other effects of the present invention can be
provided by treatment of the pulp optionally without the need for
co-addition or the co-presence in the pulp under treatment of any
nonionic or cationically charged compounds, such as a nonionic
surfactant, a cationic surfactant, a cationic polymer, or a
cationic flocculant. As an option, the method of the present
invention can be conducted free or essentially free of nonionic
surfactant and/or cationically charged compounds and/or any
additional defoaming agent, since the beneficial effects obtained
by the present invention do not rely on the co-presence of such
nonionic surfactant or cationically charged compounds or additional
defoamers. With regard to added nonionic surfactants, as an option,
the pulp can be treated with less than 0.1 kg/metric ton dry fiber,
or less than 0.05 kg/metric ton dry fiber, or less than 0.01
kg/metric ton dry fiber, or less than 0.001 kg/metric ton dry
fiber, or less than 0.0001 kg/metric ton dry fiber or in the
absence of nonionic surfactant, based on total nonionic
surfactants. With regard to added cationically charged compounds,
as an option, the pulp can be treated with less than 0.1 kg/metric
ton dry fiber, or less than 0.05 kg/metric ton dry fiber, or less
than 0.01 kg/metric ton dry fiber, or less than 0.001 kg/metric ton
dry fiber, or less than 0.0001 kg/metric ton dry fiber or in the
absence of cationically charged compounds (e.g., cationic
surfactant(s), cationic polymer(s)), cationic flocculant(s), and
the like), based on total cationically charged compounds.
[0062] As an option, the indicated at least one anionic surfactant
and at least one amide of a carboxylic acid used to treat the pulp
to improve dewatering performance can be water soluble or water
dispersible compounds.
[0063] As an option, inorganic anionic coagulants can be used, such
as polyphosphates, anionic silica sol, or any combinations
thereof.
[0064] The methods of the present invention can be used to improve
dewatering of pulpable materials, including cellulosic pulpable
materials, noncellulosic pulpable materials, recycled paper waste
pulpable materials, or any combinations thereof. As an option, the
cellulosic pulpable materials can be lignocellulosic. The drainage
and dewatering improvements due to the pulp treatment according to
methods and systems of the present invention is not limited to
treating any particular type of pulp and can find application in
all grades of pulp. The treatable pulps can be chemical pulps,
mechanical pulps, or combinations of these types of pulps. As an
option, the treatable pulp is a chemical pulp at least in part. The
treatable pulp can be bleached or unbleached when treated. The
treatable pulp can include, for example, Kraft pulp, dissolving
pulp, fluff pulp, semichemical pulps (e.g., bleached
chemothermomechanical pulp or BCTMP), sulfite pulp, soda pulp,
organosolv pulp, polysulfide pulp, or other pulps, and any
combinations thereof. Nonchemical mechanical pulps, such as pulps
mechanically defibrated only, such as by use of disk or conical
refiners only for defibration of feedstock, also can be processed
with the indicated pulp treatment.
[0065] As used herein, "dried pulp" refers to laid, stacked, piled
or otherwise physically accumulated pulp which is sufficiently
dewatered to be exposed to air and unsuspended and non-immersed in
aqueous medium.
[0066] "Anionically charged compound" refers to a compound having a
net negative charge on the molecule in aqueous solution. The
anionically charged compound can be organic or inorganic. "Organic"
means the compound contains at least one C--H bond.
[0067] "Enzyme" refers to a protein that is capable of catalyzing a
chemical reaction.
[0068] "Surfactant" refers to an organic compound which can lower
the surface tension of a liquid, the interfacial tension between
two liquids, or that between a liquid and a solid.
[0069] "Anionic surfactant" refers to a surfactant having a net
negative charge on the molecule in aqueous solution. Accordingly,
the anionic surfactant can have only anionic moieties as the
charged groups thereon or may be amphoteric with a net anionic
charge for the overall molecule.
[0070] "Nonionic compound" refers to a compound that is amphiphilic
and has no charge group at either terminal end group thereof.
[0071] "Nonionic surfactant" refers to a surfactant that is
amphiphilic and has no charge group at either terminal end group
thereof.
[0072] "Cationically charged compound" refers to a compound having
a net positive charge on the molecule in aqueous solution. The
cationically charged compound can be organic or inorganic.
[0073] "Cationic surfactant" refers to a surfactant having a net
positive charge on the molecule in aqueous solution. Accordingly,
the cationic surfactant can have only cationic moieties as the
charged groups thereon or may be amphoteric with a net cationic
charge for the overall molecule.
[0074] "Cationic polymer" refers to a polymer having a net positive
charge on the molecule in aqueous solution. Accordingly, the
cationic polymer can have only cationic moieties as the charged
groups thereon or may be amphoteric with a net cationic charge for
the overall molecule.
[0075] "Kraft pulp" refers to chemical wood pulp produced by
digesting wood by the sulfate process.
[0076] "Fluff pulp" refers to a chemical, mechanical or combination
of chemical/mechanical pulp, usually bleached, used as an absorbent
medium in disposable diapers, bed pads, and other hygienic personal
products. Fluff pulp is also known as "fluffing" or "comminution"
pulp.
[0077] "Dissolving pulp" refers to a higher purity, special grade
pulp made for processing into cellulose derivatives including rayon
and acetate.
[0078] "Bleached chemothermomechanical pulp" or "BCTMP" refers to
bleached CTMP. "CTMP" refers to chemical-mechanical pulp produced
by treating wood chips with chemicals (e.g., sodium sulfite) and
steam before mechanical defibration.
[0079] "Unitize" refers to a process by which a plurality of market
fibers can be bundled or packaged together as a single unitary
product for handling.
[0080] "Defibration" refers to separation of wood fibers by
mechanical means, chemical means, or combinations of both.
[0081] Wood chips as a source of the cellulose containing material
or that is suitable for use in the production of pulp in the
present invention can be derived from hardwood tree species,
softwood tree species, or combinations thereof. Softwood tree
species include, but not limited to: fir (such as Douglas fir and
balsam fir), pine (such as Eastern white pine and Loblolly pine),
spruce (such as white spruce), larch (such as Eastern larch),
cedar, and hemlock (such as Eastern and Western hemlock). Examples
of hardwood tree species include, but are not limited to: acacia,
alder (such as red alder and European black alder), aspen (such as
quaking aspen), beech, birch, oak (such as white oak), gum trees
(such as eucalyptus and sweet gum), poplar (such as balsam poplar,
Eastern cottonwood, black cottonwood, and yellow poplar), maple
(such as sugar maple, red maple, silver maple, and big leaf maple).
These types of woods can be used individually or in any
combinations thereof. As an option, a combination of hemlock and
cottonwood particulates can be used. As an option, the wood chips
to be pulped include virgin wood material, such as at least 50% by
weight up to 100% by weight virgin wood material. As an option,
other pulpable material may be used or included in the feedstock,
such as recycled fiber materials, such as recycled fiber from
post-consumer waste, or non-wood materials, such as grasses,
agricultural residues, bamboo, Bast materials (e.g., Ramie, flax,
hemp), or any combinations thereof.
[0082] In addition to at least one anionic surfactant and at least
one amide of a carboxylic acid, the pulps may be treated with one
or more optional additives within the pulp making system as long as
they do not interfere with the indicated function of at least one
anionic surfactant and at least one amide of a carboxylic acid to
improve dewatering performance of the treated pulps and/or foam
control and/or foam suppression. A list of optional chemical
additives that can be used in conjunction with the present
invention include, for example, pH modifiers, dry strength agents,
wet strength agents, softening agents, debonding agents, adsorbency
agents, sizing agents, dyes, optical brighteners, chemical tracers,
opacifiers, and/or dryer adhesive chemicals, and the like.
Additional optional chemical additives may include, for example,
pigments, emollients, humectants, viricides, bactericides, buffers,
waxes, fluoropolymers, odor control materials, deodorants,
zeolites, perfumes, vegetable oils, mineral oils, polysiloxane
compounds, other surfactants, moisturizers, UV blockers, antibiotic
agents, lotions, fungicides, preservatives, aloe-vera extract,
and/or vitamin E, or the like. Suitable optional chemical additives
can be retained by the pulp fibers and may or may not be water
soluble or water dispersible. As indicated, cationically charged
compounds are not required to be additionally added or present in a
pulp treatment of the present invention.
[0083] Regarding paper making sludge and the present invention, the
manufacture of paper involves blending, in water, a pulp material
(generally wood fiber) with fillers, such as clay, and other
additives to create a stock slurry mixture referred to herein as a
pulp. The pulp is then processed through a papermaking machine to
form a sheet. The water is then extracted from the sheet and the
sheet is then pressed and dried, thereby forming a paper product.
The drained water contains an amount of fiber and filler material.
This material is collected for later processing; however, the
recovery is usually not complete. Discarded material and material
not captured for reuse are generally transported to a waste
treatment facility where still-remaining solids, e.g., the fibers
and filler materials, are removed. The cleaned water is discharged
back into the environment or communicated back to the papermaking
process for reuse. After dewatering using the method of the present
invention, the solids are contained in a concentrated, typically 40
wt %-60 wt % solids, papermaking sludge. The main components of
this sludge are fibers and clay filler material. As stated, the
methods of the present invention can improve the dewatering of this
sludge, and/or control foam.
[0084] The present invention will be further clarified by the
following examples, which are intended to be only exemplary of the
present invention. Unless indicated otherwise, all amounts,
percentages, ratios and the like used herein are by weight.
EXAMPLES
Example 1
[0085] Experiments were conducted to compare water drainage of pulp
treated using an anionic surfactant
(alpha-sulfo-omega-hydroxypoly(oxy-1,2-ethanidiyl)C10-16 alkyl
ether, sodium salt CAS 68585-34-2, AKA sodium laureth sulfate
(.about.3 moles EO)) alone, an amide of a carboxylic acid
(Dimethylamide of tall oil fatty acid--DMAFA) alone, and their
combination (at different weight ratios) as added to the pulp, and
compared to water drainage of untreated pulp. A control test also
was conducted with no chemical additive used on the pulp.
[0086] The following testing procedure was applied. A slurry of
bleached pulp to be tested was prepared with a consistency of about
1 percent by weight in tap water. Water removal from the slurry was
evaluated using a Mutek DFR-05 drainage/retention tester. A
selected volume of this slurry (500 mL) was added into a chamber
which has a screen at the bottom. Any anionic surfactant and/or
amide of a carboxylic acid included in a test sample was pre-mixed
with the slurry before addition to the chamber. The screen was a
metallic mesh screen (mesh size=600 mesh). When the test was
initiated, the water was allowed to drain from the slurry through
the screen. The amount of water that drained freely from the
sample, and the rate of drainage was monitored. No vacuum nor
pressure was applied for the first 30 seconds after initiating
drainage from the chamber. At 30 seconds after the drainage is
initiated, the testing apparatus (i.e., a DFR with forced
dewatering (controlled mechanical level)) was used to apply
pressure to the pad (i.e., the fiber mat collected on the screen).
Again, the rate of water being removed from the pad was measured.
At 50 seconds additional pressure was applied, and at 70 seconds
again additional pressure was applied. This procedure, including
the amount of pressure applied at each stage, mimics the dewatering
and pressing that occurs on a paper machine or on a pulp dryer.
Free drainage rates in g/30 sec and g/90 sec were determined based
on the measurements.
[0087] The results of these experiments are shown in the Tables.
The result after 30 seconds is known as free drainage, and the data
from 30 seconds after drainage was initiated is shown in Table 1.
Table 2 below shows raw data from a set of tests. The numbers in
Table 2 are based on the grams of water drained from a sample and
are reflected as wt % water removed and final consistency (in wt
%). Note that there may or may not be a large improvement in
drainage: the more important effect is the reduction in moisture in
the sheet after the complete process of drainage, pressing and
drying and at the same time, the control of foam. That is shown in
Table 2 and FIG. 1.
TABLE-US-00001 TABLE 1 wt % water removed Ratio anionic to DMAFA in
free drainage 100 anionic/0 DMAFA 70.30 80 anionic/20 DMAFA 69.49
60 anionic/40 DMAFA 69.09 40 anionic/60 DMAFA 70.51 20 anionic/80
DMAFA 68.69 0 anionic/100 DMAFA 68.28 Blank 67.88
[0088] The results shown in Table 2 is after 90 seconds and for the
total water removed after free drainage and the 3 additional
pressings.
TABLE-US-00002 TABLE 2 wt % water Ratio anionic to DMAFA removed
final consistency (%) 100 anionic/0 DMAFA 80.40 4.90 80 anionic/20
DMAFA 79.19 4.63 60 anionic/40 DMAFA 78.18 4.42 40 anionic/60 DMAFA
80.40 4.90 20 anionic/80 DMAFA 78.18 4.42 0 anionic/100 DMAFA 77.98
4.39 Blank 76.36 4.10
[0089] As shown in the data provided, the foam-controlling additive
when used alone without the anionic surfactant provides some
improvement in dewatering but nowhere near the results provided by
the anionic surfactant. However, when the foam-controlling additive
is combined with the anionic surfactant, the results are improved,
even reaching the same maximum positive effect in some cases. This
is an unexpected result, and the primary benefit is that the
dewatering is done without the high amount of foam that occurs when
there is only anionic surfactant used. Thus, the addition of an
anionic surfactant and a dimethylamide of a fatty acid controls the
foam problem while at the same time not interfering with the
dewatering effect. These experimental results show that treating a
pulp slurry with the combination of anionic surfactant and amide of
a carboxylic acid together can provide unexpected results.
Example 2
[0090] An additional experiment was conducted to compare the
control of foam (or foam suppression) from a simulation of
agitation that would occur during a dewatering process. Pulp was
prepared in the same manner as in Example 1. The same anionic
surfactant and amide of a carboxylic acid (foam suppressing
component) was used here as in Example 1. Table 3 sets forth the
amounts of each component for each sample (samples 1 through 10).
For each test run, a sample was added, the pulp slurry was agitated
in a recirculating apparatus to cause high agitation. The foam
height that formed over a time of 10 or more seconds was recorded
and plotted in FIG. 1. Table 3 shows a legend to better understand
the results shown in FIG. 1 which shows foam height over time for
10 samples with varying amounts of anionic surfactant and foam
suppressing agent (amide of a carboxylic acid). When the foam
exceeded 24 cm in height, the test was stopped for that sample.
Otherwise, the test was conducted for almost 200 seconds. As can be
seen in FIG. 1, excellent results were achieved when the wt % for
the foam suppressing component was 50 wt % or more (based on total
weight of anionic surfactant and foam suppressing component). Foam
control was also achieved for a period of time for samples where
the foam suppressing component was present in an amount of 30 wt %
to 50 wt % (based on total weight of anionic surfactant and foam
suppressing component).
TABLE-US-00003 TABLE 3 Sample wt % anionic wt % foam suppressing
component 1 100 0 2 90 10 3 80 20 4 70 30 5 60 40 6 50 50 7 40 60 8
30 70 9 20 80 10 10 90
[0091] The present invention includes the following
aspects/embodiments/features in any order and/or in any
combination: [0092] 1. The present invention relates to a method
for dewatering a cellulose-containing material, said method
comprising: [0093] adding at least one anionic surfactant and at
least one amide of a carboxylic acid to said cellulose-containing
material to form a treated cellulose-containing material; and
[0094] dewatering said treated cellulose-containing material to
provide a dewatered cellulose-containing material. [0095] 2. The
method of any preceding or following embodiment/feature/aspect,
wherein said cellulose-containing material is an aqueous cellulosic
pulp slurry. [0096] 3. The method of any preceding or following
embodiment/feature/aspect, wherein said cellulose-containing
material is a mat of cellulosic fibers. [0097] 4. The method of any
preceding or following embodiment/feature/aspect, wherein said
cellulose-containing material is a sludge from a paper and pulp
manufacturing process. [0098] 5. The method of any preceding or
following embodiment/feature/aspect, wherein said anionic
surfactant and said amide of a carboxylic acid are added together
to said cellulose-containing material. [0099] 6. The method of any
preceding or following embodiment/feature/aspect, wherein said
anionic surfactant and said amide of a carboxylic acid are
separately added to said cellulose-containing material. [0100] 7.
The method of any preceding or following embodiment/feature/aspect,
wherein the anionic surfactant is an organic anionic surfactant.
[0101] 8. The method of any preceding or following
embodiment/feature/aspect, wherein said amide of a carboxylic acid
comprises a dimethylamide of a fatty acid. [0102] 9. The method of
any preceding or following embodiment/feature/aspect, wherein said
amide of a carboxylic acid comprises a dimethylamide of a fatty
acid having 14 to 18 carbon atoms. [0103] 10. The method of any
preceding or following embodiment/feature/aspect, wherein said
cellulose-containing material is an aqueous cellulosic pulp slurry,
and wherein said method further comprising bleaching the aqueous
cellulosic pulp slurry after pulp forming and before the adding of
the anionic surfactant and said amide of a carboxylic acid. [0104]
11. The method of any preceding or following
embodiment/feature/aspect, wherein said cellulose-containing
material is an aqueous cellulosic pulp slurry, and wherein said
method further comprising thermally drying said
cellulose-containing material that is dewatered to form market
pulp. [0105] 12. The method of any preceding or following
embodiment/feature/aspect, wherein the anionic surfactant is a
sulfate surfactant, a sulfonate surfactant, a sulfosuccinate
surfactant, or any combinations thereof. [0106] 13. The method of
any preceding or following embodiment/feature/aspect, wherein the
anionic surfactant is an alcohol sulfate, an alcohol alkoxy
sulfate, a sulfonate, a dialkyl sulfosuccinate, a sulfosuccinic
acid ester with an ethoxylated alcohol, or a soluble or dispersible
salt thereof, or any combinations thereof. [0107] 14. The method of
any preceding or following embodiment/feature/aspect, said method
further comprising bleaching said cellulose-containing material
before the adding of the at least one anionic surfactant and the at
least one amide of a carboxylic acid. [0108] 15. The method of any
preceding or following embodiment/feature/aspect, said method
further comprising adding at least one enzyme to said
cellulose-containing material before said dewatering step. [0109]
16. The method of any preceding or following
embodiment/feature/aspect, wherein said amide of a carboxylic acid
is added in an amount to control foam height during said
dewatering. [0110] 17. The method of any preceding or following
embodiment/feature/aspect, wherein the at least one anionic
surfactant and the at least one amide of a carboxylic acid are
added to the pulp in a weight ratio of from about 90:10 to about
10:90. [0111] 18. The method of any preceding or following
embodiment/feature/aspect, wherein the anionic surfactant is added
to the pulp in an amount of from about 0.1 lb./ton dry fiber to
about 10 lb./ton dry fiber, and the amide of a carboxylic acid is
added to the pulp in an amount of from about 0.001 lb./ton dry
fiber to about 2 lb./ton dry fiber. [0112] 19. The method of any
preceding or following embodiment/feature/aspect, wherein said
cellulose-containing material is formed from hardwood chips,
softwood chips, recycled paper fiber, or any combinations thereof.
[0113] 20. The method of any preceding or following
embodiment/feature/aspect, wherein the combination of treating the
pulp with the at least one anionic surfactant and at least one
amide of a carboxylic acid before said dewatering is effective to
provide at least one of the following: [0114] (i) increased
dewatering of a pulp slurry to a value which is at least 7.5% times
greater than the amount of water removed obtained without any
treatment in the pulp; [0115] (ii) reduced foam height during said
dewatering compared to foam height occurring with using the same
anionic surfactant in the absence of said amide of a carboxylic
acid. [0116] 21. The method of any preceding or following
embodiment/feature/aspect, wherein said method is effective for
increasing obtained water removal to a value which is at least five
times greater than the water removal obtained without any treatment
of the pulp. [0117] 22. A dewatered cellulosic containing material
dewatered by the method of any preceding or following
embodiment/feature/aspect, said dewatered cellulosic containing
material comprising dewatered cellulosic containing material, said
anionic surfactant and said amide of a carboxylic acid. [0118] 23.
The dewatered cellulosic containing material of any preceding or
following embodiment/feature/aspect, wherein said dewatered
cellulosic containing material is dewatered pulp or dewatered
sludge.
[0119] The present invention can include any combination of these
various features or embodiments above and/or below as set forth in
sentences and/or paragraphs. Any combination of disclosed features
herein is considered part of the present invention and no
limitation is intended with respect to combinable features.
[0120] Applicant specifically incorporates the entire contents of
all cited references in this disclosure. Further, when an amount,
concentration, or other value or parameter is given as either a
range, preferred range, or a list of upper preferable values and
lower preferable values, this is to be understood as specifically
disclosing all ranges formed from any pair of any upper range limit
or preferred value and any lower range limit or preferred value,
regardless of whether ranges are separately disclosed. Where a
range of numerical values is recited herein, unless otherwise
stated, the range is intended to include the endpoints thereof, and
all integers and fractions within the range. It is not intended
that the scope of the invention be limited to the specific values
recited when defining a range.
[0121] Other embodiments of the present invention will be apparent
to those skilled in the art from consideration of the present
specification and practice of the present invention disclosed
herein. It is intended that the present specification and examples
be considered as exemplary only with a true scope and spirit of the
invention being indicated by the following claims and equivalents
thereof.
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