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Patent 1122730 Summary

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(12) Patent: (11) CA 1122730
(21) Application Number: 1122730
(54) English Title: FLOCCULATION OF SUSPENDED SOLIDS OF MULTIVALENT CATIONS WITH ANIONIC FLOCCULANTS CONTAINING SULFONATE IONS
(54) French Title: FLOCULATION DE SOLIDES EN SUSPENSION DE CATIONS MULTIVALENTS, AVEC DES FLOCULANTS ANIONIQUES CONTENANT DES IONS SULFONATES
Status: Term Expired - Post Grant
Bibliographic Data
(51) International Patent Classification (IPC):
  • C2F 1/56 (2006.01)
(72) Inventors :
  • HALVERSON, FREDERICK (United States of America)
(73) Owners :
  • AMERICAN CYANAMID COMPANY
(71) Applicants :
  • AMERICAN CYANAMID COMPANY (United States of America)
(74) Agent: SMART & BIGGAR LP
(74) Associate agent:
(45) Issued: 1982-04-27
(22) Filed Date: 1979-10-16
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
12,274 (United States of America) 1979-02-15

Abstracts

English Abstract


27,591
Title: FLOCCULATION OF SUSPENDED SOLIDS OF MULTIVALENT
CATIONS WITH ANIONIC FLOCCULANTS CONTAINING
SULFONATE IONS
ABSTRACT OF THE DISCLOSURE
Aqueous dispersions of solids containing multivalent
cations are more readily flocculated with polymeric anionic
flocculants containing sulfonate ions than similar flocculants
containing only carboxylate ions.


Claims

Note: Claims are shown in the official language in which they were submitted.


27,591
I CLAIM:
l. A process for flocculating suspensions of solids
containing multivalent cations which comprises adding to an aque-
ous suspension of such solids an effective amount of an anionic
polymeric flocculant comprising from about 65 to about 99 mole
percent of repeating units derived from acrylamide, from about
1 to about 25 mole percent of repeating units derived from a
vinylsulfonic acid, and from 0 to about 10 mole percent of re-
peating units derived from acrylic acid, the mole percent of
units obtained from acrylic acid being less than the mole per-
cent of units derived from said vinylsulfonic acid and the poly-
meric flocculant having a Brookfield viscosity of at least about
2.60 centipoises.
2. The process of Claim 1 wherein said vinylsulfonic
acid is acrylamidomethylpropanesulfonic acid.
3. The process of Claim 1 wherein said repeating
units derived from acrylic acid is 0 mole percent.
4. The process of Claim 1 wherein said Brookfield vis-
cosity is at least about 3.30 centipoises.
5. The process of Claim 3 wherein said anionic poly-
meric flocculant comprises 3 to 15 mole percent of vinyl-
sulfonic acid.
6. The process of Claim 1 wherein said suspended
solids is Florida phosphate slimes.
7. The process of Claim 6 wherein said vinyl-
sulfonic acid is acrylamidomethylpropanesulfonic acid.
8. The process of Claim 6 wherein aid repeating
units derived from acrylic acid is 0 mole percent.
9. The process of Claim 6 wherein said Brookfield
viscosity is at least about 3.30 centipoises.
-18-

10. The process of Claim 8 wherein said anionic
flocculant comprises 3 to 15 mole percent vinylsulfonic acid.
- 19 -

Description

Note: Descriptions are shown in the official language in which they were submitted.


;2t73~
27,591
This invention relates to an improved process for
flocculating suspensions of sol ds containing multivalent
cations. More particularly, this i~vention relates to such a
process wherein the flocculant employed is a water-soluble
anionic polymer containing as its source of anionicity the
sulfonate ion.
Flocculants are reagents which are added to suspen-
sions of solids to cause the solids to flocculate and-settle.
A highly effective type of flocculant is the polymeric type
since this type can be prepared in numerous variations as des-
ired. Typically, polymeric flocculants are of three types,
nonionic, cationic, and anionic. The particular ty~e of floc-
culant to be used in a given application will generally depend
upon the nature of the surface of the suspended solids.
To provide nonionic polymers, nonionic monomers such
as acrylamide are polymerized under conditions which lead to a
nonionic polymer. Polymers containing amine groups, primary,
secondary, tertiary, and quaternary types provide typical cat-
ionic flocculants with increased charge increasing in the order
given. For anionic polymers, carboxylic acid groups are intro-
duced into the polymer. Polymers containing sulfonic acid
group were also introduced as anionic flocculants. Compari-
sons of polymers containing carboxylic acid groups with poly-
mers containing sulfonic acid groups did not distinguish be-
tween the two types of acid groups with respect to flocculant
performance in certain applications. From these comparisons,
there appears to be no advantage arising from the use of sul-
fonic acid groups as the source of anionicity.
Accordingly, there concinues to exist the need for
improved processes for flocculating suspensions of solids con-

~l22~30
taining multivalent cations that provide better performance than
can be obtained with processes employing anionic flocculants
containing carboxylic acid grou2s as the sole source of anion-
icity. The provision for such processes would fulfill a long-
felt need and constitute a singificant advance in the art.
In accordance with the present invention, there is
provided a process for flocculating suspensions of solids con-
taining multivalent cations which comprises adding to an aqueous
suspension of such suspended solids an effective amount of an
anionic polymeric flocculant comprising from about 65 to about
99 mole percent of repeating units derived from acrylamide,
from about 1 to about 25 mole percent of repeating units derived
from a vinyl sulfonic acid, and from 0 to about 10 mole percent
of repeating units derived from acrylic acid, the mole percent
of units obtained from acrylic acid being less than the mole
percent of units derived from said vinylsulfonic acid and the
polymeric flocculant having a Brookfield viscosity of at least
about 2.~0 centipoises.
The process of the present invention provides more
rapid flocculation of suspensions containing multivalent cations
at a given flocculant dosage than can be achieved with proces-
ses employing anionic flocculants deriving their anionicity
solely from carboxylic acid grol!~s. The process of the present
invention also provides equal performance at lower flocculant
dosages than can be obtained with processes employing anionic
flocculants deriving their anionicity solely from carboxylic
acid groups. These results are surprising in view of the fact
that polymers containing either type of anionic ~roup are sub-
stantially equivalent in performance when used in applications
where multivalent cations are absent and suspension is not too
acidic.
- 2 -

2t73~
27,591
As indicated, the process of the present invention
involves the use of an anionic flocculant deriving its anioni-
city from a content of sulfonic acid groups. Polymeric floc-
culants useful in the process of the present invention are
readily prepared using known processes.
A particular preferred type of anionic flocculant is
one containing repeating units derived from acrylamide and a
vinyl sulfonic acid, the latter constituting about 1 to 25 mole
percent, preferably 3 to 15 mole percent, of the total polymer
composition. A preferred vinyl sulfonic acid monomer is acryl-
amidomethyIpropanesulfonic acid.
~ The polymeric flocculants used in the process of the
present invention will have molecular weights useful in floccu-
lating applications according to conventional teachings. Parti-
cularly useful flocculants are those that have Brookfield viscos-
ities of at least about 2.60 centipoises, preferably at least
about 3.30 centipoises. Brookfield viscosity is the viscosity of
a 0.08% solution of the polymer in 1 normal NaCl at 25C. with pH
adjusted to 8-.5 determined with a Brookfield viscometer using the
UL adapter and the spindle rotating at 60 RPM.
In carrying out the process of the present invention,
an aqueous solids suspension containing multivalent cations is
selected for treatment. A particularly preferable multivalent
cation suspension is that represented by Florida phosphate slimes.
Other suspensions containing Ca+2, Al+3, Fe+3, Fe+2, Mg+2, Be+2
or the like may also be effectively treated. Florida phosphate
slimes contain Ca+2 cations as well as other multivalent cations
in suspension. Many colored wastes are treated with alum or fer-
ric chloride to precipitate the colorants from solution. These
precipitates which remain suspended contain Al+3 or Fe+3 cations.

~22~3~)
To flocculate the solids in these aqueous suspensions,
an effective amount of the specified anionic flocculant is add-
ed to the suspension. This addition is generally made in a man-
ner which provides uniform distribution of the flocculant
throughout the suspension so as to obtain maximum flocculation
of solids. Mixing may be an added operation or may be inherent
in processing, such as addition to a moving stream of suspen-
sion en route to a settling tank. An effective amount of floc-
culant is that amount which produces the desired level o~ floc-
culation and will vary widely depending upon many factors such
as the nature of the suspension, the specific flocculant em-
ployed, the extent of flocculation or settIing rate desired,
and the like. Generally, the amount of flocculant will follow
conventional dosages except that the present invention allows
for reductions in such dosages in appropriate instances. Usual-
ly a dosage of about 0.01 to 1.0 milligram of flocculant per
liter of suspension will be effective.
The invention is more fully illustrated in the exam-
ples which follow wherein all parts and percentages are by
weight unless otherwise specified. The following procedures
were employed in evaluating performance of the process.
PHOSPHATE SLIMES SETTLING TEST
Florida phosphate slimes are adjusted to a solids
level of 1.0~ with water and 1000 ml. of the resulting suspen-
sion are placed in a one-liter graduated cylinder. The desired
weight of polymer flocculant is prepared as a solution in 50 ml.
deionized water. This flocculant solution is admixed with the
slimes in the cylinder with agitation to ensure thorough mix-
ing of slimes with flocculant, the agitator is removed, and
time during which the solids/liquid level settles from the
-- 4 --

~L~ZZ73~
1000 ml. mark to the 800 ml~ mark is recorded. The distance
between these two marks varies between cylinders, but in the
set for these experiments it is 7.20+0.08 cm. Average rate of
settling over this distance is given in units of cm./sec.
COLOR REMOVAL
~rest Procedure
A Phipps-Bird six place gang stirrer, equipped with
3/4" x 1 3/4" paddles, was used for jar tests. Five hundred
milliliters of the water to be treated were added to each of
six 600 ml. beakers and placed on the stirrer. With the pad-
dles rotating in the water at 150 rpm, a specified amount of
alum (as a 1% solution) was added to each beaker, the additions
being as near to simultaneous as possible. Stirring at 150 rpm
was continued for 30 seconds after alum addition, then was
reduced to 40 rpm. At the end of 3 minutes stirring was in-
creased to 150 rpm, and the high molecular weight anionic poly-
mer was added to each beaker as a solution in 30 ml. deionized
water. Stirring at 150 rpm was continued for-30 seconds,
then reduced to 40 rpm for 3 minutes, at which time stirring
was stopped and paddles were raised out of the beakers.
Floc size was estimated during the latter part of the
stirring period, on a scale of 1 to 10, with 1 representing
flocs smaller than 0.5 mm, and 10 representing flocs lcm or
larger. The contents of the six beakers in a set (those being
~5 treated simultaneously) were compared visually in terms of rate
of settling of flocs, and ranked from 1 to 6, with 1 being the
most rapid in the set. Residual soluble color was monitored
by removing supernatant from each beaker at the end of five
minutes, and measuring the optical density of a 4 cm path.
Solution color removal is determined primarily by the precipi-

~lZ;~:~30
.
tation with aluminum, rather than by anionic flocculant addi-
tion, and so does not vary much for a fixed alum addition.
HUMATE WASTES--SETTLING TE5T No .
-
Seven hundred milliliters of humate wastes are placed
in a 1 liter graduated cylinder. Fifty milliliters of 1~ FeSO4
7H20 solution are diluted to 150 milliliters total volume, and
then added to the graduated cylinder with agi~ation to insure
uniform mixing. The polymeric flocculant then is added to the
cylinder as a solution in 150 ml of deionized water, with mix-
ing to provide adequate dispersion of the polymer solution
throughout the suspension for about 5-10 seconds. Following
addition of the polymeric flocculant, very mild agitation is
provided by three 1/8" diameter stainless steel fingers posit- -
ioned equidistantly along the circumference of a circle with a
radius about one half the internal radius of the cylinder, ex-
tending from the top to bottom of the cylinder, and moved
along the path of the circle at a rate of one revolution per
minute. The height of the solidsjliquid interface is recorded
as a function of time after addition of polymeric flocculant.
HUMATE WASTES-SETTLING TEST No. 2
Seven hundred milliliters of humate wastes are
placed in a 1 liter graduated cylinder. The pH is adjusted to
7.0 with 0.5N NaOH. Fifty milliliters of 1~ FeSO4.7H2O solu- -
tion are diluted with deionized water, in an amount necessary to
provide a total volume of 850 ml in the graduated cylinder when
added to the humate wastes~ This ferrous sulfate solution is
added to the cylinder with agitation to insure thorough mixing.
A solution containing 5 mg polymeric flocculant in 150 ml deion-
ized water then is added slowly to the cylinder (over about
10-15 seconds), with agitation to provide thorough mixing of
-- 6 --

Z;~730
flocculant with the suspension. Following addition of the
polymeric flocculant, very mild agitation is provided by three
1/8" diameter stainless steel fingers extending from top to
bottom of the cylinder, and traversing a cylindrical path in
the cylinder with a radius about one half the radius of the
cylinder. Each finger completes one traversal along the peri-
phery of the circle per second. The height of the solids/
liquid interface is recorded as a function of time after ad-
dition of flocculant. The rate of settling is computed from
the number of minutes required for the interface to settle one
centimeter below the 1000 ml mark on the graduated cylinder.
EXAMPLES 1 and 2
Following the Settling Test procedure, rates of set-
tling at pH 7.5 as a function of flocculant dosage (mg polymer/
g dry slime solids) over a commercially viable range were
determined and the results are given in Table I which follows
which also indicates the polymer composition and Brookfield
viscosity.
.

1~2Z73(~
TABLE I
SETTLING RATES OF FLORIDA PHOSPHATE SLIMES
Exam-Exam- Comp. Comp.
ple 1 ple 2 A B
Polymer Composition (Mole %)
Acrylamidomethylpropane-
sulfonic acid ~15 7 0 0
Acrylic Acid ~ 0 0 12 7
Acrylamide 85 93 88 93
Brookfield Viscosity(cps.)3.3 3.4 3.9 3.4
Settling Rates cm/sec.
Dosage mg/g 0.025 0.045 - - -
0.050 0.140 0.062
0.075 0.200 0.105
0.100 0.270 0.160 0.072
0.125 - 0.205 0.100
0 150 - - 0.135 0.115
0 175 - - 0.195 0.135
0 200 - - - 0.165
0 225 - - - 0.195
Q As sodium salt.
The results given in Table I above indicate the super-
ior settling rates achieved at lower polymer dosages using
polymers containing ionicity derived from sulfonate groups.
EXAMPLES 3 - 6
Comparisons in performance can be made via dosages
necessary to achieve a fixed settling rate from plots of the
settling rate at various polymer dosages. Using this procedure,
the polymer dosage required to provide a settling rate of
0.144 cm./sec. (17 ft./hr.) was determined using the same slimes
as in Examples 1 and 2. The dosage value (D) is given below
in Table II along with polymer compositions and Brookfield
, viscosities.
- 8 -

~22730
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EXAMPT~E 7
Using phosphate slimes obtained from another source,
settling tests to determine the dosage requirements for a set-
tling rate of 0.144 cm./sec. were determined operating at pH=
7.85 . The polymers employed and the dosage requirements are
given in Table III which follows.
TABLE III
DOSAGE REQUIREMENTS FOR SETTLING
OF FLORIDA PHOSPHATE SLIMES
_ Example
Polymer Composition (Mole %) 7 Comp. G
Acrylamidomethylpropane-
sulfonic acid 4
Acrylic Acid 2 7
Acrylamide 94 93
Brookfield Viscosity (c~s) 3.4 3.4
Dosage for 0.114 cm./sec.
settling rate (mg/g) 0.125 0.310
EXAMPLES 8 - 10
Using the procedure color removal described above,
the effluent tested was a deep amber colored suspension with
low solids from a paper mill in North Carolina. The suspension
pH was adjusted from 7.8 to 6.5 with sulfuric acid. Alum add-
ition was at a level of 350 ppm. A series of tests were run
with aliquots of the suspension using flocculants at various
dosages. The flocculant of Examples 8-10 contained 7 mole per-
cent acrylamidomehtylpropanesulfonic acid and 93 mole percent
acrylamide. The Comparative Flocculant G contained 7 mole per-
cent acrylic acid and 93 mole percent acrylamide. Details and
results are given in Table IV.
-- 10 --

~L~l22730
TABLE IV
COLOR REMOVAL USING ALUM
FOLLOWED BY FLOCCULA~ION
_
Flocculant
Brookfield Dosage Floc Perform-
Example Viscosity (Mg/l) Sizeance Rank
(cps)
8 3.4 0.1 3 3
9 3.4 0.2 5 2
3.4 0.3 6
G, run 1 3.4 0.1 2 6
G, run 2 3.4 - 0.2 2 5
G, run 3 3.~ 0.3 2 4
Thus, 0.1 mg/l of the flocculant of the invention pro-
vides more rapid clarification than 0.3 mg./l. of the compara-
tive flocculant.
EXAMPLES 11 - 13
The procedure of Examples 8-10 was repeated in every
material detail except for the flocculants employed. The floc-
culant of Examples 11-13 contained 5 mole percent acrylamido-
methylpropanesulfonic acid and 95 mole percent acrylamide~ The
Comparative Flocculant H contained 3.5 percent acrylic acid and
96.5 percent acrylamide. Details and Results are given in
Table V,
TABLE V
COLOR REMOVAL USING ALUM
FOLLOWED BY FLOCCUhATION
-
Flocculant
Brookfield Dosage Floc Perform-
Example Viscosity ~ /1) Size an~ce_Rank
- (cps)
11 3.6 0.1 5 3
12 3.6 0.2 6 2
13 3.6 0.3 7
H, run 1 3.5 0.1 3 6
H, run 2 3.5 0.2 4 5
H, run 3 3.5 0.3 4 4
Again, 0.1 mg/l of the flocculant of the invention pro-
vides more rapid clarification than 0.3 mg/l of the comparative
-- 11 --

~;Z730
flocculant.
EXAMPLES 14 - 16
Again repeating the procedure of Examples 8-10 in
every material detail, two additional flocculants were evaluated.
The flocculant of the invention contained 15 mole percent acryl-
amidomethylpropanesulfonic acid and 85 mole percent acrylamide.
- The Comparative Flocculant I contained 12 mole percent acrylic
acid and 88 percent acrylamide. Details and results are given
in Table VI.
TABLE VI
COLOR REMOVAL USING ALUM
FOLLOW~D BY FLOCCULATION
Flocculant
Brookfield Dosage Floc Perform-
ExamPleViscosity (Mq/l) Size ance Rank
( cps )
14 3.3 0.1 2 3
3.3 0.2 3 2
16 3.3 0.3 4
I, run 1 3.9 0.1 1 5
I, run 2 3.9 0.2 1 6
I, run 3 3.9 0.3 1 4
EXAMPLES 17 - 19
Again repeating the procedure of Examples 8-10 in
every material detail, two additional flocculants were evalu-
ated. The flocculant of Examples 14-16 contained 15 mole per-
cent acrylamidomethylpropanesulfonic acid and 85 mole percent
acrylamide. The Comparative Flocculant J contained 15 mole per-
cent acrylic acid and 85 mole percent acrylamide. Details and
25results are given in Table VII.
- 12 -

~122730
TABLE VII
COLOR REMOVAL USING ALUM
FOLLOWED BY FLOC~ULATION
Flocculant
Brookfield Dosage Floc Perform-
Example Viscosity (Mg/l) Size ance Rank
(cps)
17. 4.0 0.1 4 3
18 4.0 0.2 5 2
19 4.0 0.3 7
J, run 1 4.6 . 0.1 1 6
J, run 2 4.6 0.2 1 5
J, run 3 4.6 : 0.3 1 4
_X~M-PL~S 20-22
Again following the procedure of Examples 8-10 in
every material detail, two additional flocculants were evaluated~
The flocculant of Examples 0-22 contained 7 mole percent
acrylamidomethylpropanesulfonic acid and 93 mole percent acryl-
amide. The Comparative Flocculant K contained 7.7 mole percent
acrylic acid and 92.3 mole percent acrylamide. Details and
results are given in Table VIII.
TABLE VIII
COLOR REMOVAL USI~G ALUM
FOLLOWE~ ~Y FLOCCULATION
Flocculant
BrookfieldDosage Floc Perform-
Example Viscosity(Mg/l) Size ance Rank
( cps )
4.7 0.1 4 3
21 4.7 0.2 5 2
22 4.7 0.3 6
K, run 1 4.4 0.1 2 6
K, run 2 4~4 0.2 2 5
K, run 3 4.4 0.3 2 4
EXAMPLES 23-25
Again following the procedure of Examples 8-10 in
every material detail, two additional flocculant~ were evalu-
ated. The flocculant of Examples 23-25 contained 5 mole percent
acrylamidomethylpropanesulfonic acid and 95 mole percent acryl-
- ~3 -

1~22~730
amide. The Comparative Flocculant L contained 4 mole percent
acrylic acid and 96 mole percent acrylamide. Details and res-
ults are given in Table IX.
TABLE IX
- 5 COLOR REMOVAL USING ALUM
FOLLOWED BY FLOCCULATION
Flocculant
Brookfield Dosage Floc Perform-
Example Viscosity (Mg/l) Size ance Rank
(cps)
23 4.8 0.1 5 3
24 - 4.8 0~2 8 2
4.8 0.3 9
- L, run 1 4.2 0.1 1 6
L, run 2 4.2 0.2 2 5
L, run 3 4.2 0.3 2 4
EXAMPLE 26
Following the Humate Wastes-Settling Test No. 1,
humate wastes from effluent stream to settling pond 20 grams
solids per kilogram of substrate and pH 5.9 were treated with two
flocculants in separate runs. Details and results are given
below.
TABLE X
SETTkING RATES OF HUMATE WASTES
Example Comparative
- Polymer Composition (Mole%) 26 Example M
Acrylamidomethylpropane-
sulfonic acid~(AMPS)7 0
Acrylic Acid~ (AA) 0 7.7
Acrylamide (AM) 93 92.3
Brookfield Viscosity 4.7 4.4
Note 0As sodium ~alt
The polymer of Example 26 provided an average settling
rate of 0.24 centimeter per minute over 7.2 centimeters at a
dosage of 0.36 milligrams polymer per gram of solids. For the
- 14 -

Z730
same settling rate, the polymer of Comparative Example M re-
quired a dosage of 5 milligrams of polymer per gram of solids.
E~AMPLE 27
Following the procedure of Example 26, two additional
5polymers were evaluated. Details and results are given below.
TABLE XI
SETTLING RATES OF HUMATE WASTES
Example Comparative
Polymer Composition (Mole %) 27 Examp-e N
AMPS ~ 15 0
- .10
AA ~ 0 15
AM 85 - 85
Brookfield Viscosity4.0 4~6
For a settling rate as in Example 26, 0.36 mg/gram
solids of the polymer of Example 27 was required. For the same
settling rate, 5 mg/gram solids of the polymer of Comparative
Example N was required.
EXAMPLE 28
Again following the procedure of Example 26, two
additional flocculants were evaluated. Details and results are
given below.
TABLE XII
SETTLING RATES OF HUMATE WASTES
Example Comparative
Polymer Composition tMole ~) 28 Example O
AMPS ~ 5
AA ~ o 3 5
AM 95 86.5
Broo~field Viscosity 3.6 3~5
-- 15 --

~;2Z730
For a settling rate as in Example 26, the dosage re-
quired for the pol,vmer of Comparative Example 0 was four times
that required for the polymer of Example 28.
EXAMPLES:29 - 32
The procedure of Humate Wastes-Settling Test No. 2
was followed using eight polymer flocculants in separate runs,
four of the invention and four comparative. Details and
Results are given below~
- 16 -

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Representative Drawing

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Administrative Status

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Event History

Description Date
Inactive: Expired (old Act Patent) latest possible expiry date 1999-04-27
Grant by Issuance 1982-04-27

Abandonment History

There is no abandonment history.

Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
AMERICAN CYANAMID COMPANY
Past Owners on Record
FREDERICK HALVERSON
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 1994-02-15 1 10
Cover Page 1994-02-15 1 26
Claims 1994-02-15 2 42
Drawings 1994-02-15 1 6
Descriptions 1994-02-15 17 494