Note: Descriptions are shown in the official language in which they were submitted.
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CARBONACEOUS MATERIALS IN WATER SLURRIES
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to carbonaceous materials
in water slurries and more particularly to coal in water
slurries stabilized with ammonium salts of
naphthalenesulfonic acid formaldehyde condensates.
2. Description of the Prior Art
Transport is one of the major problems involved
in use of particulate carbonaceous materials such as coal.
One method of transport involves aqueous slurries.
However, aqueous slurries of finely ground coal containing
over 55 weight percent solids are difficult to pump with
slurry pumps. This is because as the solids level is
increased above 50 weight percent, water and solids tend
to separate causing coal particles to build up in various
areas in the pumping system. This dewatering of the
slurry causes blockage and jamming in the pumping system.
On the other hand, 'decreasing the welght percent
of water in aqueous coal slurries is desirable because
water is a major contributor to the cost of transport and
processing operations. The less water transported the
greater is the volume of coal that can be moved, resulting
in transport efficiencies. Further, water resources are
limited. Also, during burning of coal, a significant
amount of heat is required to vaporize the water. As the
weight percent of water decreases, the efficiency of the
coal burning process increases. Hence, use of higher
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weight percent solids aqueous carbonaceous slurries than
were heretofore feasible would be of great importance.
U.S. Patent No. 4,282,006 - Funk, August 4,
1981, describes a pipeline pumpable coal water slurry
having a high content of coal particles with a minimwm of
void spaces and a maximum of particle surface area to
enhance dispersing effects genera~ed by electrolytes
and/or dispersing agents added to the slurry. For
dispersing agents, see Column 29, line 53 to Column 31,
1 10 line 9, including condensed mononaphthalene sulfonic acid
and its sodium and ammonium salts (Column 30, lines 19 and
20).
Thus, in accordance with the present teachings, an im~
provement is provided in a water slurry of carbonaceous
materials composition comprising water and carbonaceous mat-
erials. The improvement which is provided is having presen-t
in the slurry an effective amount of ammonium salt of a
naphthalenesulfonic acid formaldehyde condensate sufficient
to reduce the viscosity, to improve pumpability and to mini-
mize ash or slag formation, the anioni~ portion of the salthaving an equivalent elution volume of size exclusion
chromatography of frc~ about 61~ to about 71% of ~ tc~tal elution.
DETAILED DESCRIPTION
The ammonium salt of naphthalenesulfonic acid
formaldehyde condensate, hereinafter referred to as
ammonium condensate for convenience, is present in the
slurry in amounts sufficient to reduce viscosity of the
slurry and improve its pumpa~ility. Concentration of the
ammonium condensate added, based on the total weight of
the carbonaceous materials water slurry, can be up to 10%
by weight, preferably from about O~Ol~/o by weight to about
5.0% by weight. For example, from about 0.05% by weight to
about 0.5% by weight of the ammonium condensate, based on
the total weight of the slurry, i.e., solids plus water,
can be used. Amount o the ammonium condensate is easily
determined by introctucing the condensate in an amount
sufficient to form a soft sediment. The resulting
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slurries will generally have from about 50 to about 80% by
weight solids or higher with the balance being water.
Ammonium salts of naphthalenesulfonic acid formaldehyde
condensates have the following advantages over sodium or
other metal salts of these condensates:
(a) Ammonium condensates do not contribute
to ash or slag formation during
combustion of slurry;
(b) Ammonium condensates have improved
performance as slurry stabilizers;
(c) Solutions of ammonium condensates
have lower manufacturing cost; and
; (d) Solutions of ammonium condensates
have improved cold storage stability.
~mmonium condensates are introduced into
slurries at any convenient point: during their preparation.
The term "carbonaceous materials", as used
herein, encompasses solid particulate carbonaceous fossil
fuel materials which may have been powdered or pulverized
to a size where at least 80% will pass through a 200 mesh
screen (U.S. Series). Useful carbonaceous materials
include bituminous and anthracite coals, coke, petroleum
coke, lignite, charcoal, peat, admixtures thereof and the
like. These materials are crushed and milled to obtain
finely divided particles suitable for use in pumpable
water slurries.
Water used in slurries may be taken from any
available source such as mine, well, river, or lake water
or desalinated ocean water having a sufficiently low
mineral salt content such that the electrochemistry of the
bound water layer and carrier water interface can be
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controlled and corrosion of milling facilities, pipelines
and furnaces will be minimized and controllable.
The ammonium salt of naphthalenesulfonic acid
formaldehyde condensate may be prepared by reacting
naphthalene with formaldehyde and sulfuric acid and
ultimately treating with ammonium hydroxide. Useful
processes are described in U.S. Patent No. 2,141,569 -
Tucker et al - December 27, 193~; U.S. Patent No.
3,193,575 - Nebel et al - July 6, 1965 and U.S. Patent No.
i 10 3,277,162 - Johnson - October 4, 1966.
A naphthalenesulfonic acid formaldehyde
condensate is a mixture of condensation products of
naphthalenesulfonic acid and formaldehyde. It can be
chromatographed by size exclusion chromatography through a
column containing pore sizes which selectively separate
molecular volumes according to size. The solvent chosen
for the acid in chromatography should minimize solute-
packing interaction and solute-solute interaction. The
chromatogram gives a true molecular volume profile when
the eluents are displayed on a detector-strip chart
recorder display. The chromatogram for a sample of the
sulfonic acid used in the examples is the same as that for
the sodium naphthaleneformaldehyde sulfonate in U.S.
Patent No. 3,9~4,491 - Adrian et al - May 4, 1976, and the
two anionic materials are identical. That is, the anionic
materials from the sulfonic acid have the same profile as
the anionic materials from the sodium naphthaleneformal-
dehyde sulfonate having lowest elution volumes of from
about 61 to about 70% of the total elution volume and
equivalent elution volumes of from about 61 to about 70%
of the total elution volume.
.
This chromatographic method was
described by Dr. Harold Edelstein in a paper entitled,
"Aqueous Gel Permeation Chromatograph of Some Naphthalene
Sulfonic Acid Formaldehyde Condensates" presented at the
Mini Symposium of the North Jersey Chromatography Group
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Subsection of the A.C.S. on March 6 9 1978 at Hoffman La
Roche Auditorium, Clifton N.J.
Evaluation of Stabilizers for
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Aqueous Carbonaceous Slurries
The following procedure is used in the
evaluation of ammonium salts of naphthalenesulfonic acid
formaldehyde condensates in aqueous coal slurries in the
examples given below. This procedure determines ability
of these ammonium condensates to disperse or -suspend coal
dust uniformly in water by measuring viscosity.
Ap~aratus Used
8 oz. paint can
Low shear mechanical mixer with a double blade
Spatula
Stormer viscometer
Reagents Used
Water of known record hardness
Coal dust - Reference coa:L is Pittston Coal, 80%
through 200 mesh (U.S. Series). Other types of
coal and grind sizes can be substituted.
Stabilizing agent
Procedure
1. A slurry of coal dust in water is prepared as
follows. Coal dust is slowly added to water
under agitation by a low shear mechanical mixer
with a double blade. Sides of the container are
scraped regularly while mixing. The slurry is
agitated for an additional hour to ensure
uniformity. The weight % solids in the slurry
is determined by difference.
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2. Viscosity of the aqueous coal slurry is
determined by weighing out 200 gram samples of
the slurry into 8 oz. paint cans. ~ specific
quantity of the ammonium condensate is added to
each can under vigorous agitation. A
concentration range of ammonium condensate of
from 0.10 to 1 gram/200 grams is used. Each can
can is closed tightly to prevent evaporation of
water.
3. Each can is opened and each slurry is stirred
with a spatula before viscosity measurements are
made with a Stormer Viscom2ter. Weights are
adjusted in order to find a reading as close as
possible to 30 seconds and the correct weight
for a 30-second viscosity is determined.
Readings are repeated twice after stirring each
time. Readings should not differ by more than 2
seconds. Readings are repeated until consistent
and the average of two readings taken. Readings
on slurries covering a broad concentration range
of ammonium condensate are taken to the point
where the ammonium condensate no longer reduces
viscosity of the slurry and/or coal precipitates
from the slurry.
4. Seconds and weight are converted into krebs
units. Krebs units are then converted to
centipoise readings.
For a fuller ~mderstanding of the nature and
advantages of this invention, reference may be made to the
following examples. These examples are given merely to
illustrate the invention and are not to he construed in a
limiting sense. All quantities, proportions and
percentages are by weight and all references to
temperature are C unless otherwise indicated.
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EXAMPLE I
Samples of coal water slurries were treated with
the quantities of solutions of sodium condensate (sodium
salt of naphthalenesulfonic acid formaldehyde condensate)
and ammonium condensate (ammonium salt of
naphthalenesulfonic acid formaldehyde condensate) shown in
the table below. The coal water slurries were 60% by
weight slurries of Pittston coal dust in tap water. A
sample of coal slurry on drying was found to contain 59.1%
solids. Quantity in the table is the quantity of additive
solution added to 200 g of coal water slurry. An
untreated sample of the coal slurry was used as the blank
and samples treated with sodium condensate were used as
the control. The additive solution used as a control was
a 34% sodium condensate solution. The other two additive
, solutions were a 40% ammonium condensate solution having a
pH of 6.5 and a 42.3% ammonium condensate solution having
a pH of 4Ø Samples of the blank, control and ammonium
condensate treated slurries were then evaluted by the
procedure described above to obtain the following results:
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Additive
Quantity Solution Additive (g) Stormer
(g3 (% by weight) Coal (g) wt sec KU cps
- Blank - 80032 132 4000
0.10 34% sodium 0.00028 30028 93 1230
condensate
0.15 34% sodium 0.00043 20030 82 925
condensate
0.20 34D/o sodium 0.00057 17529 76 766
condensate
0.25 34% sodium 0.00071 15025 66 460
condensate
0.35 34% sodium 0.00099 12531 68 500
condensate
0.10 40% ammonium 0.00033 20032 83 950
condensate
0.15 40% ammonium 0.00050 17529 76 766
condensate (30)
0.20 40% ammonium 0.00067 17530 77 800
condensate
0.25 40% ammonium 0.00083 12530 67 480
condensate
0.10 42.3% ammonium 0.00035 250 27 86 1033
condensate
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0.15 42.3% ammonium 0.00053 175 29 76 766
condensate
0.20 42~3% ammonium 0.00070 150 30 72 633
condensate
0.25 42.3% ammonium 0.00088 125 29 66 460
condensate
While the invention has been described with
reference to certain specific embodiments thereof, it is
understood that it is not to be so limited since
alterations and changes may be made therein which are
within the full intended scope of the appended claims.
