Note: Descriptions are shown in the official language in which they were submitted.
~ ~1 8 ~
COAL SLURRY COMPOSII'ION
BACK~ROUND OF THE INVENTION
This inven-tion relates generally to aqueous slurry
compositions of coal. More specifically, the invention
relates to a coal slurry composition which is an aqueous
slurry composition of coal powder having a specific
particle size distribution, possesses excel]ent disper-
sion stability, and, moreover, does not form a hard cake
by consolidation of sediments tending to occur when left
standing for a long period, that is, has excellent
stability when left to lie still.
In recent years, diversification of energy sources
and ensuring of stable supplies of energy have become
important problems because of reasons such as limits to
the reserves of petroleum, which has heretofore been
used in greatest quantity as an energy source and the
consequent rise in prices of petroleum products. In
viewof these circumstances, the effective utilization of
coal, which is still available in great reserves and is
not maldistributed but exists throughout the world, is
being reconsidered.
In the case o coal, however, since it is a solid,
differing from petroleum, transporta-tion thereof through
pipelines is not readily possible, whereby coal is
markedly disadvan-tageous in handling. Further, since
coal, in general, contains a great ash content in
. . . _
g ~
comparison with petroleum, there arise problems such
as lower calorific value and the need -to dispose of
fly ash. Accordingly, with the object of overcoming
these difficulties in handling coal, various studies
are being made on methods of pulverizing coal, dis-
persing it in water to render it into slurry form, and
using the slurry.
However, a slurry of this character is accompanied
by the problems of a great increase in viscosity when
the coal concentration is increased, which results in a
loss in fluidity, a drop in transfer efficiency when,
conversely, the coal concentration is decreased, and,
further, high cost also in the water removal step, and
it is difficult to discover a suitable coal concentra-
tion. This is attributable to agglomeration in thewater of the coal particles in the coal-water slurry,
which causes an increase in the slurry viscosity and a
reduction in its fluidity. In a coal-water slurry, the
smaller the coal particles are, the better is the dis-
persion stability, but the cost of fine pulverizationincreases with increase in the degree of fineness of
pulverization.
When a surface-active agent (hereinafter referred
to as a surfactant), which is a dispersant, is added to
a coal-water slurry, the surfactant is adsorbed on the
interfaces of the coal particles and the water and gives
rise to such effects as separation of the coal particles
away from each other and prevention of the coal particles
from mutually agglomerating, whereby the surfactant can
be expected to create a good dispersion state~ As dis-
persants of this character, alkyl (phenyl) ether sulfate
(Japanese Patent Laid Open Publication No. 20090/1981),
sulfonated products of polycyclic aromatic compounds
having in some cases a hydrocarbon group as a substituent
and salts thereof (Japanese Laid Open PubLication No.
21636/1981) and others have been proposed.
However, in the case where these dispersants are used,
while the fluidity is improved, sediments which set-tle
when the slurry is left standing for a long period con-
solidate and form a hard cake, which has been a great
problem in actual practice.
SU~ARY OF THE INVENTION
Accordingly, we have carried out a research direct-
ed toward obtaining a coal-water slurry in which the
above described problems have been solved, and which has
excellent fluidity and has no tendency to form a hard
cake, that is, has excellent stability when left standing
(hereinafter referred to as "static stability"). As
a result, we have arrived at and developed this invention.
According to this invention, briefly summarized,
there is provided a coal slurry composition comprising,
essentially:
(a) a coal powder of which 71 to 85 percent by weight
are coal particles of particle sizes of 74~ or smaller,
1 ~ 8 ~
and which, moreover, has a particle size distribution
such that, when said distribution is represented on a
Rosin-Ra~nler chart, the gradient (in terms of the
value of tan ~) of the straight line joining two points
respectively corresponding to the quantity (percent by
weight) of particles of particle sizes less than 44~
and to the quantity (percent by weight) of particles of
particle sizes less than 74~ is 0.4 to 0.9;
(b) at least one species of surfactant selected
from the group consisting of sulfonated products of
naphthalene and creosote oils, salts thereof and addi-
tion condensation products thereof with an aliphatic
aldehyde, and addition condensation products of amino-
triazines containing a sulfonic acid group with an
aliphatic aldehyde, and salts thereof; and
(c) water.
The precise reasons why the coal-water slurry of
this invention has excellent fluidity and static
stability are not entirely clear but are thought to be
as follows. In a coal powder wherein the coal particle
si~e distribution has been specially adjusted as in the
above mentioned component (a), the fine coal particles
are adsorbed around the coarse coal particles to form a
loose network structure. As a result, the separation
by settling of the coarse coal particles is suppressed,
and the standing stability becomes good. Furthermore,
the fine coal particles enter into the gaps between the
coarse coal particles, whereby a state close to that
of maximum-density filling is attained, and for this
reason the slurry has fluidi-ty even with a high coal
concentration. The surfactant which is the component
Ib) is an anionic surfactant and, being adsorbed in
great quantity on the coal ma-terial within the coal
particles in the coal-water slurry, imparts an electric
charge, thereby improving the dispersibility of the
coal particles in the slurry and thus increasing the
fluidity.
The coal-water slurry of this invention, because
of the above described constitution, has good fluidity
and excellent static stability. The phrase "good
static stability" as used herein includes the case
wherein the sediments are soft and are easily re-
dispersed. Particularly, in contrast to a coal-water
slurry of the prior art obtained by using only a dis-
persant, in which, when left standing, sediments form a
consolidated hard cake, in the coal-water slurry of this
invention, a hard cake of this nature is not formed.
For this and other reasons, the industrial worth of this
invention may be said to be very high.
The nature, utility, and fur~her features of this
invention will be more clearly apparent from the follow-
ing detailed description commencing with a considerationof general aspects of the invention and concJuding with
a presentation of preferred embodiments thereof including
--5--
cj ~
synthesis examples and examples cf practice when read
in conjunction with the accompanying drawings, briefly
described below.
~RIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is an example of a Rosin-Rammler chart
indicating the particle size distribution of coal powder
used in the preparation of a coal slurry composition,
the nlimbers (No.) in this chart correspondiny to the
numbers of the coal powder components la) usecl in Example
1 set forth hereinafter; and
FIG. 2 is a simplified elevation showing a rod
penetration testing apparatus for use in evaluating
the static stability of coal slurry compositions.
DETAILED DESCRIPTION OF THE INVENTION
Composition
The coal slurry composition of this invention com-
prises com~onents (a), (b) and (c) stated hereinabove.
The preferable proportions of the components in the
co~l slurry composition of this invention are as follows.
Throughout the following description and in the accompany-
ing drawings, quantities expressed in percent (%) and
parts are by weight. The preferable proportion of the
component (a), coal powder, is 50 to 80%; that of the
component (b~, surfactant, is 0.01 to 5%; and that of
the component (c), water is 15 to 45%. Particularly,
60 to 75% of the component (a), 0.03 to 2.0% of the
t ~
component (b), and 25 to 35% of the ccmponent (c) are
more preferable.
Coal owder
Particles of the coal powder used in this inven-
tion of particle sizes of 74 microns (~) or smallerare in a proportion of 71 to 85 percent. When direct
combustion of the slurry is considered, it is preferable
that particles of particle sizes of 74~ and smaller be
in a proportion of 75 to 80 percent. Furthermore, it is
necessary that this coal powder have a particle dis-
tribution such that the value of -tan ~. (alpha) is 0.4
to 0.9, preferably 0.5 to 0.8, where tan ~ is the slope
or gradient of the straight line joining the point
indieating -the quantity (percent) of partieles of partiele
sizes smaller than 44~ and the point indieating the
quantity (percent) of particles of partiele sizes smaller
than 74~ when plotted on a Rosin-Rammler ehart.
As long as these eonditions are satisfied, the line
indieating the partiele size distribution obtained by
~0 plotting on this ehart may be straight line, a eurved
line, or a eombination of a straigh-t line and a eurved
line. Furthermore, it may be a line having a point of
infleetion. In addition, the eoal powder used may laek
a partiele size fraetion which has been separated through
elassification processing.
As shown in FIG. 1, in a Rosin-Rammler chart, the
abscissa represents particle size (diameter) on a
s ~ ~
logarithmic scale, and the ordinate represents
quan-tity passing through (percent) on a special scale.
This kind of chart is being widely distributed by
Nippon Funtai Kogyo Kyokai (Japan Powder Industries
Association) and other organizations.
In general, in the case where a coal is pulverized
simply in a ball mill or the like, the coal powder
obtained will not satisfy the particle size distribu-
tion conditions as described above and has a relatively
narrow particle size distribution of a value of tan ~
of the order of l.0 to 1.2. With a coal powder having
a particle size distribution of this character, an
aqueous slurry having excellent dispersion stability
coupled with excellent standing stability, which is the
object of this invention, will not be obtained.
In order to obtain coal powder having a par-ticle
size distribution as described above which can be used
in this invention, it is necessary to resort to a
specially devised powder preparation method and not to
use a simple pulverizing method. For example, a method
such as that wherein a plurality of pulverizing machines
are used in parallel to produce a suitable particle size
distribution or that wherein, after pulverization with
a pulverizing machine, classification with sieves is
carried out can be adopted. The pulverizing machine may
be of any suitable form such as a ball mill, COlloid mill,
or attritor. The pulverizing method may be dry-type
pulveriza-tion or wet-type pulverization in water.
We have found tha-t a coal concentration in the
coal slurry composition of 50 to 80 percent, parti~
cularly 60 to 75 percent, is desirable. If this con-
centration is too low, the calorific value of theslurry will drop, and, at the same time, direct com-
bustion will become difficult. On the other hand, if
the concentration is excessively high, the slurry
viscosity wi]1 become excessively high, and the slurry
fluidity will kecome poor. Although the optimum con-
centration differs with the specie of coal and its
particle size, a concentration within the above stated
ranges will be found to be suitable in almost all cases.
~his invention is applicable to coals such as anthracite,
bituminous coal, sub-bituminous coal, brown coal and
the like.
Dispersion aid-Surfactants
As mentioned hereinabove, an aqueous slurry of coal
powder of a specified particle size distribution is
stabilized, when the slurry comprises an anionic surfact-
ant (Component b) of a restricted group as set forth below,
to have dispersion stability, static stability and
fluidity which are remarkably higher than those obtain-
able when the dispersion is stabilized with a surfactant
of another grOup.
As to such surfactants, mention is made to sulfonated
products of naphthalene or creosote oils, salts thereof
and addition condensation products thereof with an
aliphatic aldehyde; and addition condensation products
of an aminotriazine with an aliphatic aldehyde contain-
ing the sulfonic acid group and salts thereof. Examples
of the salts of the sulfonated products include alkali
metal salts such as sodium or potassium salt, alkaline
earth metal salts such as calcium or magnesium salt, and
ammonium and amine salts. In production of these sur-
factants, the sulfonation step, the step of condensation
with an aliphatic aldehyde and the step for convertion
into a salt can be conducted in any sequencial order.
Among these surfactants, those which have formaldehyde
addition-condensed therewith are especially effective,
wherein the degree of addition-condensation of formalde-
hyde is preferably 1.2 to 30, more preferably 1.2 to lO.
When the degree of addition-condensation of formaldehyde
is lower than 1.2, the benefit afforded by the conden-
sation is not very high, and when the degree of addition-
condensation is higher than 30, on the other hand, the
product is not very practicable due to poor solubility.
The term "degree of addition-condensation" or simply
"degree of condensation" means the number of aryl rings
such as naphthalene rings in the condensate produced.
The term "creosote oils" used in the present inven-
tion means neutral oils having a boiling point of 200C
-10--
or higher derived from the tar produced from dry distil-
lation of coal or an alkylated product thereof. Creosote
oi.ls have heretofore been defined in several ways, but
JIS (Japanese Industrial Standards) K 2439 (1978) tells
that a creosote oil is a mixture of fractions not lower
than middle oil region derived from distillation of coal
tar, and is a product produced by blending fractions of
middle oil, heavy oil, anthracene oil,etc., from which
crystallizable ingredients such as naphthalene and
anthracene and some other ingredients such as phenols and
pyridines have been removed. Creosote oils available on
the market in Japan are classified into types No.l, No.2
and No.3, creosote oil type No.l, for example, being a
mixture of various compounds which meets such a specifi-
cation that specific gravity is 1.03 or higher, moisture
content is 3% or lower, and comprises 25% or lower of a
fraction having a boiling point of 235C or lower, and
40% or higher of a fraction having a boiling point of 235
to 315C, the content of a fraction which is distilled
off at 315C or lower being 50% or higher.
In the practice of the present invention, any of the
creosote oils specified under JIS K 2439 (1978) and
fractions obtained by distillation of the creosote oil
such as those having a boiling point of 200 to 250C, of
240 to 260C, of 250 to 270C, or of 270 to 300C are
usable. The alkylated products of the creosote oils or
the fractions obtained therefrom are also usable and are
included in the term 'icreosote oils". In production of
the alkylated products, any suitable alkylation process
can be resorted to. Sulfonation by means of fuming or
conc. sulfuric acid in the presence of an alcohol
results in concomitant alkylation. Examples of alcohols
for alkylation includes monohydric alcohols of from 3 to
8 carbon atoms.
The addition-condensation products of aminotri-
azines with an aliphatic aldehyde which have a sulfonate
group are addition-condensation products of amino-S-
triazines. Examples of the products include -those
produced by a process taught in Japanese Patent Publica-
tion No.21659/1968. The addition-condensation products
are obtained by addition-condensing an amino-S-triazine
such as melamine, hexamethylol melamine, acetoguanamine
or benzoguanamine with an aliphatic aldehyde, preferably
formaldehyde, and sulfonating the condensate obtained with
a sulfonating a~ent such as sulfurous acid, sulfuric acid,
sulfonic acid, hydrogen sulfurous acid, or a salt thereof,
disulfite, dithionite, or pyrosulfite salt, or by addi-
tion-condensing an amino-S-triazine sulfonic acid with
an aldehyde, preferably formaldehyde. In one preferable
embodiment of the present invention, the amino-S-triazine
addition-condensation product is a sulfonated melamine
resin which is produced from melamine-formaldehyde
condensate sulfonated by Na2S2O3 or NaHSO3 to introduce a
sulfonate group thereinto.
-12-
Production of the slurries-water content
The coal-water slurry of coal ~owder in accordance
with the present invention can be produced by any suit-
able process or method. The process or method may, in
general, comprise providing coal powder of a specified
particle size distribution and processing the coal powder
to form an aqueous slurry which contains the specified
surfactant.
The content of water (Component(c)) in the slurry in
accordance with the present invention is signifi.cant. If
the water content is low, the dispersion stability will
not be improved even if a surfactant, which is the
Component (b), is added, and only a slurry of inferior
fluidity can be obtained. On the other hand, when water
is used in a proportion of 15 percent or more, preferably
25 percent or more, the dispersion stability is remark-
ably improved, and the fluidity also becomes excellent.
However, when water is used in a great quantity, the
calorific value decreases, and direct combustion also
becomes difficult, and for this reason, a large content
of water should be avoided. Accordingly, it is desirable
that the water content be 15 to 45 percent, particularly
25 to 35 percent.
PREFERRED EMBODI~ENTS OF THE INVENTION
In order to indicate more fully the nature and
utility of this invention, the following examples o~
synthesis of some surfactants (Component (b)) and a
f. ~
specific example of practice of the coal-water slurry
of this invention are set forth, it being understood
that these exa~ples are presented as illustrative and
are not intended to limit the scope of the invention.
Synthesis Example 1
567 parts o-f 37% formalin is adjusted to have pH
4.5 with caustic soda, and 294 parts of melamine is
then added thereto. The mixture is heated to 75C into
a clear solution. The solution is cooled to 45C, and
222 parts of Na2S2O3 is then added there-to. To the
product is then added 332 parts of water and the product
produced is adjusted to have pH 10.5 with caustic soda.
The solution is then heated at 80C for 2 hours. The
solution is cooled to 50C, and is admixed with 2116
parts of water and 70 parts of conc. sulfuric acid.
The mixture is heated at 50C for 5 hours, and is adjust-
ed to have pH 8.7 with caustic soda.
The solution thus obtained has a solid content of
ca. 20%, a viscosity of 37 cp at 25C, and is miscible
with water in various proportions.
Synthesis Example 2
567 parts of 37~ formalin is adjusted to have pH 4.5
with caustic soda, and 294 parts of melamine is then
added thereto. The mixture is heated to 75C into a clear
solution. The solution is cooled, and 222 parts of
Na2S2O3 is then added thereto. To the solution is added
332 parts of water, and the solution is then adjusted to
-14-
have pH 9.0 with caustic soda. The solution is heated
at 80C for 2 hours. ~he solution is diluted with 2000
parts of water and is then cooled. The solution has
a viscosity of 26.2 cp. and a solid content of ca.
20~.
Synthesis Example 3
Acetone guanine sulfonic acid is admixed with 30%
formalin in a mole ratio of 1:4.0, the mixture produced
is heated to 70C, is adjusted to have pH 4.0 with
caustic soda, and is then heated at 90C for 2 hours.
The solution thus obtained, which is miscible with water
in various proportions, has a viscosity of 346 cp. at
20C and a solid content of ca. 50%.
Synthesis Example 4
Benzoguanamine sulfonic acid is admixed with 30~
formalin at a mole ratio of 1:4Ø The admixture is then
heated to 70C, adjusted to have pH 4.0, and is then
heated at 90C for Z hours. The solution thus produced,
which is miscible with water in various proportions,
has a viscosity of 2330 cp. at 2nC and a solid content
of ca. 50%,
Example 1
1) Preparation of coal powder
A ball mill of 30-cm diameter was charged with
magnetic balls (comprised of a mix-ture in a ratio of
1:1 of l-cm diameter balls and 0.5-cm diameter balls)
in a quantity corresponding to approximately 1/2 of the
~ ~s :~ s ~
interior volume of the ball mill and 2 kg oE Tatung
coal in one instance and Miike coal in another instance.
The compositions of these coals are shown in Table 1.
Pulverization was then carried out by rotating the
ball mill at 50 rpm for 1 hour in each instance. The
coal powder thus obtained was classified with sieves
of 45-, 100-, 200-, and 350-mesh sizes, whereupon it was
found to have a particle size distribution as shown in
Table 2.
With Tatung coal and Miike coal and by a similar
method, pulverization and classification by sieving of
a great quantity of coal were carried out, and five
lots of coal powder divided respectively into particles
remaining on a 48-mesh sieve, those of 48- to 100-mesh
size, those of 100- to 200-mesh size, those of 200-
to 325-mesh size, and those passing through a 325-mesh
sieve were obtained. These five lots of powder were
blended in the proportions set forth in Table 3 thereby
to prepare a plurality of coal powder samples respective-
ly of specific particle size distributions. The pro-
perties of these coal powder samples are shown in Table
4, and a Rosin-Rammler chart for some of these coal powder
samples is shown in FIG. 1. The sieve used for classifi-
cation is the Tyler Sieve shown in, for example, PERRY:
CHEMICAL ENGINEERS HANDBOOK.
-16-
Table 1. Coa.1 composition
Elementary analysis
Coal mine Country _ _ (dr 7 basis)
Coal C _ H _ N S
Coal Tatung Chl~.a 4 5 7 00.9
. sample Mlike Jap 4.8 6 70.9 25.9
Table 2
Particle size distribution (wt.%)
Remaining¦ Passing
on a 48- ¦48 - 100 100 - 200 200 - 325 through a
mesh ¦ mesh mesh mesh 325-mesh
sieve* ¦ sieve
Component 39 23 18 8 12
_
No.9 6 ~ 19 25 18 32
* Tyler sieve
~ ~8~
Ta~le_
__ _
Blending proportion (wt.~)
Component Remaining _ _ _ Passing
(a), No. on a 48-48 - 100 100 - 200 200 - 325 through
mesh mesh mesh mesh 325-mesh
sieve _ _ sieve
2 18 22 25 12 23
__ l
3 6 ]9 1 25 118 32
___ I
4 0.5 6.5 1 18 20 55
_ . _ _
27 11 ]2 8 42
6 17 15 18 13 1 32
7 - 6 7 1 12 8 6'
l .
8 2 7 16 11 64
, I
0.5 6.5 1 18 1 20 55
I
11 6 7 12 8 67
-18~
4. ~
Tab e 4
_ ._
Gradient, tan ~,of
Component Coal 74-~ particles line joining points
(a), No. sample and smaller of wt.~ passing
No.(wt.%) through 44~ and of
wt % passing throuch
1* 1 20 1.0
2* " 35
3* ll 50
0 4* ll 75
~ ~ u.
8 " ll 0.7
9* 2 50 1.0
~ 75 5
* Comparison product
-19-
3, ~
2) Production of coal slurry
Aqueous solutions of the surfactant components
indicated in Tab]es 5 and 6 and various surfactant
components prepared in the aforedescribed synthesis
examples were prepared by adding specific quantities
of the surfactants to water. To each of these aqueous
solutions, specific quantities of the coal powders,
which are the components (a), prepared in section 1)
set forth above. Each mixture thus obtained was agitat~
ed for 5 minutes in a mixer "Homomixer" (mfd. by Tokushu
Kikako, Japan) operated at 5,000 rpm to prepare a coal
slurry composition of a specific concentration. The
blending proportions of the components are set forth in
Table 6.
-20-
Table 5. (1) Components Ib), surfactants
Component _
(b), No. Compound
b-1-(lj naphthalenesulfonic acid Na salt
" " (2) formalin condensate of b-1-(1)
(degree of condensation 2)
" " (3) (ditto)
(degree of condensation 4)
. ' " (4~ (ditto)
(degree of condensation 8)
" " (5) naphthalenesulfonic acid
" " (6) formalin condensate of b-1-(5)
(degree of condensation 2)
" " (7) (ditto)
(degree of condensation 4)
" " (8) (ditto)
(degree of condensation 8)
-21-
3 ~
Table 5 (2)
Component ¦ Compound
No. I
b-3-(1) sulfonation product (Na salt) of creosote ( 1)
oil
" " (2) formalin condensate of b-3-(l)(degree of con-
densation 2)
" " (3) (ditto) ( " " 4 )
" " (4) (ditto) ( " " 6)
" " (5) sulfonation product (Na sa]t) of butylated
creosote oil
" " (6) formalin condensate of b-3-(5) (degree of
condensation 2)
" " (7) sulfonation product (Na salt) of hexylated
creosote oil
" " (8) formalin condensate of b-3-(7) (degree of
condensation 4)
(9) sulfonation product (Na salt) of creosote oil
formalin condensate (degree of condensation 3)
" " (10~ sulfonation product (Na salt) of creosote oil-
naphthalene mixture (1:1 by wt.)
" " (11) formalin condensate (Na salt) (degree of con-
densation 4) of sulfonation product (Na salt)
of creosote oil - butylnaphthalene mixture
(1:1)
" " (12) formaline condensate of b-3-(10) (degree of
condensation 4)
c-l sodium lignosulfonate
c-2 polyoxyethylenenonylphenylester (EO: 7 mol)
c-3 sodium alkylbenzenesulfonate (alkyl group
C = 12)
* creosote oil type 1.
-22-
s3
3) Evaluation of fluidity and static _tability
The viscositi.es at 25 C of the coal slurry com-
positions prepared in section 2) were measured, and the
respective fluidities were evaluated. A lower viscosity
of slurry has better fluidity.
Next, the static stabillties of the coal slurry
compositions were evaluated by using a glass rod inter-
penetration testing apparatus of the construction and
size shown in FIG. 2. In FIG. 2, the unit of height
dimensions is millimeter (mm). Each of the coal-water
slurries 2 prepared as described hereinbefore in section
2) was left standing in a 500-cc measuring (graduated)
cylinder 3 for one day. Thereafter, the time for inter-
penetration of a vertical glass rod 1 of 50-g weight
through each slurry composition was measured and taken
as the measure of its static stability. That is, if
the sedimentary substances in the slurry form a hard
cake and consolidate, the interpenetration time will be
long, and, in an extreme case, the glass rod will stop
at an intermediate point. On the other hand, when the
slurry has good static stability and does not separate,
or, even if it separates somewhat, the sediments are
soft, the interpenetration time will be short. The
results of this test are shown in Table 6.
-23-
g
~ r _ I T- ~r
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~ h ~ _ _ _ _ _ _ _ _ _ t - _
~ ~ ~ o ~ ~ ~
V ~ 0 (^') -K ~ ~ . . .
h K l l l l l la) O = = = O ~ L'~
o '~ R.. ~ ~1
CQ O t~ l O h
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r-l -K X X X X X X O O <3 O O O O O
.
_ _ __ _ _ _
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~1 O ~I p A = = = = = t~ `J ~ ~\1~ ~ ~ r-l
~>
~D _ O _ _ __ _
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~2 ~ O ~ o = _ _ = = ~1 = _ = = _ _ _
0 ~ Q _
E~ ~Oo o o
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O ~_)
~ _ ____ __
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// O - ~ h :~
// C~ h ~ ~5
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-24 -
~ ~ ~ - -
~ ~ : l ~ o o o o o o o o o o
~ lo
c) ~ ~ ~
.~ ,~ ~ I l l ~ o o ~r ~ o o ~ ~ ~ o
v~ a~
~
~ ~ x x x o o o ~ o o ~ o o o o
~ -- -
~ ~ o o o o o o o o o o o o
~1 ~1 O CO C~ r--l L') CO 111 ~1 CO ~ O L'')
U~ S~ O Ir) ~ ~D ~ O O O O O t- t~l
O ~ Q ~ O = = ~ ~1 _ L') ~1 ~1 ~I
t~l,. 0-`1 ,
~D ~ _ _ _ _ _ _
Q ~ ~ O ~
n~ ~ O ~ ~1 = = = = _ = = = = = = = =
E~ ~ ~ Q
a) o o o
~ a _ _ _ _ _ _ _ _ .,.
~D ~J e~ ~1 t~l ~) L') ~D r-- CO
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