Process for pumping a carbonaceous slurry

A process for pumping a carbonaceous slurry which contains at least about 60 volume percent of solids is disclosed. The slurry used in this process has a carbonaceous consist with a particle size distribution in substantial accordance with a specified CPFT formula. The slurry is pumped in a substantially laminar regime, at a Reynolds number of less than about 2100.

TECHNICAL FIELD 
A process for pumping a carbonaceous slurry which contains at least about 
60 volume percent solids is disclosed. In this process, the slurry is 
pumped in a substantially laminar regime. 
BACKGROUND OF THE INVENTION 
Coal is a major source of energy in the United States. It is increasing in 
importance because of its abundance within the United States and because 
of the security and balance of payments problems which arise from reliance 
upon foreign oil. 
Transport problems constitute one of the major difficulties in the use of 
coal. Many attempts have been made to solve this problem by preparing 
slurries of coal with carrier liquid and pumping said slurries from one 
point to another. However, the prior art processes which relate to the 
pumping of carbonaceous slurries suffer from several distinct 
disadvantages. In the first place, they generally cannot utilize more than 
about 50 weight percent of carbonaceous material in the slurry to be 
pumped; above this critical amount, the slurry ususally becomes 
unpumpable. In the second place, the slurry must be pumped in a turbulent 
regime, thus increasing the amount of energy consumed by the process; 
unless such turbulent regime pumping occurs, the slurry undergoes an 
unacceptable amount of settling. 
3.(a). Prior art teachings regarding the solids content of a coal water 
slurry and its effect upon pumpability. 
The prior art appears to disclose that, in coal-water slurries, when the 
solids content exceeds a certain critical value, the slurry becomes 
unpumpable. 
An early patent, issued in September of 1920, places this critical value at 
about 20 weight percent of coal. U.S. Pat. No. 1,390,230 of Bates 
discloses that "Attempts have been made to carry or force coal through 
pipes by means of water, but owing to rapid sedimentation it has been 
possible to convey as a maximum only about 20% by weight of particles 
under considerable head of water travelling some twenty feet per second. 
Save under such exceptional circumstances or in rivers, water has not 
served as a carrier to transport coal. Only very small amounts may be made 
into a colloidal with water, and so made naturally stable for 
transportation." (At lines 48-59 of page 1) 
In May of 1957, when Clancey et al. issued U.S. Pat. No. 2,791,471, this 
"critical value" was placed somewhat higher. At lines 13-19 of Column 2 of 
this patent, it is taught that " . . . coal at the slurry preparation 
terminal . . . is mixed with water to form a slurry . . . . The resulting 
slurry should contain about 35 to 55 percent coal by weight." A similar 
disclosure appears in U.S. Pat. No. 2,791,472 of Barthauer et al., which 
also issued in May of 1957. At lines 45-49 of the Barthauer et al. patent, 
it is disclosed that "Coal selected for pipeline shipment is crushed to a 
suitable size consist, screened and mixed with water to form the slurry 
for transportation. The resulting slurry should contain about 35 to about 
55 percent coal by weight." 
In January of 1960, Wasp et al. issued U.S. Pat. No. 2,920,923. In this 
patent, they discussed the prior art Clancey et al. process and stated 
that "Certain hydraulic principles relating to pipeline transportation 
have been set forth in U.S. Pat. No. 2,971,471. A commercial pipeline, 
embodying these hydraulic principles, has been constructed in Ohio . . . . 
This coal is mixed with an equal weight of water to comprise a 50 percent 
aqueous coal slurry." (Lines 24-38 of Column 1) 
In January of 1963, U.S. Pat. No. 3,073,652 was issued to Reichl. The 
Reichl patent appears to disclose that the aforementioned "critical value" 
of solids content could be as high as 60 weight percent. At lines 30-40 of 
column 1 it is stated that "The coal particles, that is both the fine and 
coarse particles, are mixed with water to form a coal-water slurry having 
a solids concentration of between 35 and 60 percent by weight coal 
particles. It has been discovered that a slurry prepared as described 
above is dynamically stable in that the tendency of the larger sized coal 
particles to settle out of the slurry is reduced . . . . " However, as is 
taught in the Cole et al. patents, the coal concentrations taught in 
Reichl appear to be calculated on a "wet basis" and, thus, apparently 
correspond to "dry basis" coal concentrations of up to about 45 weight 
percent. 
In February of 1965, U.S. Pat. No. 3,168,350 was issued to Phinney et al. 
In the Phinney et. al. patent, reference is again made to the prior art 
Clancey et al. process disclosed in U.S. Pat. No. 2,791,471. With regard 
to the prior art process, Phinney et al. stated that "The process employed 
to transport the coal as an aqueous slurry through this commercial 
pipeline is set forth in U.S. Pat. No. 2,791,471 . . . . The coal 
particles having the above size distribution and nominal top size are 
mixed with water to prepare a slurry comprising 35-55 percent by weight of 
the coal particles and the remainder water." (Lines 25-37 of column 1) 
In December of 1976, a U.S. patent issued which disclosed that, at above a 
solids content of 50 percent of coal (dry basis), a slurry is unpumpable. 
U.S. Pat. No. 3,996,026 of Cole disclosed that "Ordinarily, a pumpable 
slurry of solid fuel or coal requires the addition of water to the 
powdered fuel to form a slurry containing not more than about from 40 to 
45 wt. % coal. As the solids content increases above this range the slurry 
becomes increasingly difficult to pump and at about 50% solids content, it 
is unpumpable (at lines 29-36 of column 1). Cole also teaches that the 
as-mined coal contains a substantial amount of moisture and, unless it is 
dried, a slurry containing 50 weight percent of such as-mined coal in fact 
contains substantially less than 50 weight percent of coal. At lines 37-47 
of his patent, he discloses that "Actually such slurries contain in excess 
of 50% water as there is a considerable amount of water in coal as mined . 
. . . The coal or solid fuel also contains chemically bound water . . . 
depending on the type of solid fuel, a pumpable slurry may contain as 
little as 30 to 35 wt. % solids on a dry basis." 
In May of 1978 yet another patent issued disclosing that a pumpable 
coal-water slurry could contain no more than about 40 to about 45 weight 
percent of coal. U.S. Pat. No. 4,088,453 disclosed that "The amount of 
water necessary to form a pumpable slurry depends on the surface 
characteristics of the solid fuel . . . in the case of a slurry made up of 
solid fuel particles most of which will pass through a 200 mesh sieve it 
has been found that ordinarily, a pumpable slurry must contain from 55 to 
60 wt. % water." (Column 1, lines 25-46) 
In August of 1978, U.S. Pat. No. 4,094,035 issued to Cole et. al. It also 
contained disclosure that a coal-water slurry with more than 50 weight 
percent of coal was unpumpable; the portion of U.S. Pat. No. 3,966,026 
quoted hereinabove was included verbatim in the Cole et. al. U.S. Pat. No. 
4,104,035 patent. 
In summary, the prior art appears to indicate that the coal content of 
coal-water slurries generally must be maintained at less than about 50 
weight percent in order for these slurries to be pumpable. 
3.(b). Prior art teachings regarding the solids content of a coal-water 
slurry and its effect upon stability. 
The prior art appears to disclose that the use of a high solids content in 
a coal-water slurry has an adverse affect upon the stability of the 
slurry. U.S. Pat. No. 4,242,098 discloses that "Aqueous slurries of finely 
ground coal containing more than about 55 weight percent solids are 
difficult to transport using conventional slurry pumps because as the 
solids level is increased above about 50 weight percent the water and 
solids tend to separate causing coal particles to build up in various 
areas throughout the pumping system." (Column 1, lines 15-21) 
3.(c). Prior art teachings regarding the solids content of a coal-oil 
slurry and its effect upon pumpability. 
U.S. Pat. No. 3,907,134 teaches that the use of more than 50 weight percent 
of coal in a coal-oil mixture has an adverse effect upon the pumpability 
of the mixture. At lines 41-50 of Column 1, it is disclosed that "The fuel 
oil and particulate carbonaceous material are preferably mixed in metered 
amounts . . . . For most users about 5 weight percent of coal or less is 
not normally economically interesting, and above 50 weight percent of 
pulverized coal begins to cause undesirable flow characteristics in the 
slurry." 
U.S. Pat. No. 3,846,087 discloses that, with regard to carbon-oil slurries, 
" . . . major problems are encountered in maintaining the carbon-oil 
slurry pumpable when the carbon content thereof exceeds about 4 weight 
percent in naphtha, gas oil, lube oil, shale oil, decanted oil, gasoline, 
crudes deficient in +1000.degree. F. boiling material or in hydrogen 
deficient in +1000.degree. F. boiling material. Above this figure, the 
slurry does not flow and upon heating only becomes more gel-like" (lines 
8-15 of Column 1). 
3.(d). Prior art teachings about pumping a coal-liquid slurry in a 
turbulent regime. 
The prior art appears to disclose that most coal-liquid slurries must be 
pumped in a turbulent flow regime. "Turbulent flow" has been defined as 
"a. Fluid motion in which random motions of parts of the fluid are 
superimposed upon a simple pattern of flow . . . . b. A fluid flow in 
which there is an unsteady motion of the particles, the motion at a fixed 
point being inconstant. Turbulent flow occurs at a speed above the 
critical velocity of Reynolds." A dictionary of mining, mineral, and 
related terms, edited by Thrush (U.S. Department of the Interior, 1968), 
page 1175. The "Reynolds' critical velocity" " . . . is that at which the 
flow changes from laminar to turbulent, and where friction ceases to be 
proportional to the first power of the velocity and becomes proportional 
to a higher power--practically the square." A dictionary of mining, 
mineral, and related terms, supra, page 279. It appears that the prior art 
teaches that, in order to pump a coal-fluid slurry, it must be pumped at a 
speed above the critical velocity of Reynolds. 
U.S. Pat. No. 2,920,923 of Wasp et al. discloses that there is a "minimum 
non settling velocity" which is required to prevent settling of solids in 
a moving slurry. This minimum settling velocity is required because " . . 
. the transportation of slurries is made possible by the existence of 
turbulent eddy currents which continually resuspend the coarser particles 
of the slurry." (Column 4, lines 27-30) 
U.S. Pat. No. 3,206,256 of Scott discloses that "The transportation of such 
granular material is known and presents the problem of maintaining the 
granules in suspension within the carrier liquid. Thus, when as is usually 
the case, the particles have a density greater than that of the carrier 
liquid they tend to settle to the bottom of the pipe line unless the flow 
velocity is sufficient to create the turbulence required to counteract 
settling . . . " (Column 1, lines 22-28). 
U.S. Pat. No. 3,268,263 of Van Olphen discloses that " . . . the 
transportation of granular materials . . . in a carrier liquid through a 
pipe line is known. Such transportation presents the problem of 
maintaining the granules in suspension within the carrier liquid due to 
the different, usually greater density of the granules. The settling 
problems, considerations affecting settling rates, and certain remedies . 
. . are considered in the U.S. Pat. Nos. 2,929,923 to Wasp et al. and 
2,610,900 to Cross. As is evident from these disclosures, the granules are 
kept in suspension within the carrier liquid through turbulence, and for 
each system there is a `minimum non-settling velocity,` which must be 
maintained if settling is to be avoided." (Column 1, lines 21-36) 
U.S. Pat. No. 3,514,217 of Reiss discloses that "When transporting solids 
as a slurry in a pipeline, the flow velocity of the slurry must be 
maintained above some critical value, V.sub.c, in order to fully suspend 
the solid. If the flow velocity falls below the critical velocity, solids 
will settle on the bottom of the pipe. This is known as unstable slurry 
flow and may result in the pipeline becoming plugged . . . " (Column 1, 
lines 28-34) 
It is the object of this invention to provide a process for pumping a 
high-solids content (60-82 volume percent) carbonaceous slurry in the 
laminar regime. 
SUMMARY OF THE INVENTION 
A process for pumping a carbonaceous slurry comprising the steps of 
providing a specified carbonaceous slurry and pumping said slurry in the 
laminar regime is disclosed. The slurry used in the process of this 
invention contains from about 60 to about 82 volume percent of 
carbonaceous solid material, from about 18 to about 40 volume percent of 
carrier liquid, and from about 0.01 to about 4.0 weight percent of 
dispersing agent; the carbonaceous solid material in the slurry has a 
particle size distribution substantially in accordance with a specified 
CPFT formula; and the slurry has a Brookfield viscosity at 100 r.p.m. of 
less than 5,000 centipoise.

DETAILED DESCRIPTION OF THE INVENTION 
6.(a). A grinding mixture which can be used to prepare a carbonaceous 
slurry. 
The slurry used in the pumping process of this invention can be prepared by 
grinding a grinding mixture until a slurry with certain specified 
properties is obtained. 
In one aspect of this invention, a grinding mixture is provided. This 
grinding mixture contains from about 60 to about 82 parts by volume of 
carbonaceous material, from about 18 to about 40 parts by volume of 
carrier liquid, and from about 0.01 to about 4.0 parts, by weight of dry 
carbonaceous material, of dispersing agent; the pH of this grinding 
mixture is from about 5 to about 12. 
The grinding mixture can be provided either prior to or during grinding. In 
one embodiment, the carbonaceous material, carrier liquid, and dispersant 
are mixed to provide the grinding mixture, and the mixture so provided is 
then ground to produce a stable slurry. The aforementioned materials can 
be mixed by means well known to those skilled in the art including, e.g., 
blending them together, grinding them together, and combinations of 
blending and grinding them together. In another embodiment, all of the 
carbonaceous material desired in the grinding mixture is mixed with less 
than all of the carrier liquid and/or dispersant desired in the grinding 
mixture, and the incomplete mixture is then ground while the remainder of 
the carrier liquid and/or the dispersant is added during grinding; in this 
embodiment, the desired grinding mixture is generated in situ during 
grinding. In another embodiment, less than all of the carbonaceous 
material desired in the grinding mixture is mixed with carrier liquid and 
dispersant, and the incomplete mixture is then ground while the remainder 
of the carbonaceous material is added during grinding; in this embodiment, 
the desired grinding mixture is also generated in situ during grinding. 
Other embodiments will be apparent to those skilled in the art. Any 
embodiment wherein the specified grinding mixture is present and is ground 
to produce the specified slurry described which is then pumped in the 
laminar regime is within the scope of applicant's invention. 
As used in this specification, the terms "mixed" and "mixing" refer to the 
steps of combining or blending several masses into one mass and includes, 
e.g., blending, grinding, milling, and all other steps by which two or 
more masses are brought into contact with each other and combined to some 
extent. Conventional means for mixing viscous materials can be used in the 
process of this invention. Thus, by way of illustration and not 
limitation, one can use batch mixers such as change-can mixers, stationary 
tank mixers, gate mixers, shear-bar mixers, helical blade mixers, 
double-arm kneading mixers, screw-discharge batch mixers, intensive 
mixers, roll mills, bulk blenders, Littleford-Lodige mixers, cone and 
screw mixers, pan muller mixers, and the like; one can use continuous 
mixers such as single-screw extruders, the Rietz extruder, the Baker 
Perkins Ko-Kneader, the Transfer-Mix, the Baker Perkins Rotofeed, 
twin-screw continuous mixers, trough and screw mixers, pug mills, the 
Kneadermaster, and the like. 
In the process of this invention, a specified slurry is provided and 
pumped. Thus, e.g., in one embodiment, a mixture comprising from about 60 
to about 82 volume percent of one or more solid carbonaceous materials 
(such as, e.g., coke and/or coal) and one or more carrier liquids (such 
as, e.g., water and/or oil) is ground until a slurry with specified 
properties is obtained, and the slurry is then pumped. Said carbonaceous 
material/carrier liquid mixture is hereinafter referred to in this 
specification as the "grinding mixture". 
The grinding mixture is preferably comprised of at least one carbonaceous 
solid material. As used in this specification, the term "carbonaceous" 
refers to a carbon-containing material and includes, by way of 
illustration and not limitation, coal, coke, graphite, charcoal, char, and 
the like. The preferred carbonaceous materials are carbonaceous fuels. 
In one preferred embodiment, the carbonaceous solid is coal. By way of 
illustration, anthracite, semi-anthracite, medium, and high-volatile 
bituminous, sub-bituminous and lignite coals may advantageously be used to 
practice the invention. 
The coal for use in the process can be obtained in a dry or wet form and 
mixed with fluid to form a coal-fluid mixture. Preferably, the coal for 
making a fine particle sized fraction is wet milled in known ways to 
prevent dust and explosion hazards, while optionally adding dispersing 
agent(s) to the fluid. The wet milled coal fraction can be milled with all 
the water, or it can be mixed with sufficient additional water to make a 
slurry when it is further mixed with a coarser crushed coal fraction. 
In view of the manner in which coal fractures during milling, coal 
particles will have irregular shapes which, however, are of a body (or 
maximum side-to-side thickness) such that the sub-sieve sized discrete 
particles will pass through a specified mesh of a sieve. The size of the 
discrete particle can be expressed in terms of a spherical diameter which, 
as used herein, is defined as a U.S. sieve size of from 4 mesh (4760 
.mu.m) to 400 mesh (38 .mu.m) through which a coal particle from a sample 
of coal or coal-water slurry will pass. For particles finer than 200 mesh 
(74 .mu.m), the size of the particles can be determined by means of a 
sieve, or a sedimentometer, or a scanning electron microscope (SEM), or 
the like. 
In one preferred embodiment, the carbonaceous solid material is coke. Coke 
is the solid, cellular, infusible material remaining after the 
carbonization of coal, pitch, petroleum residues, and certain other 
carbonaceous materials. The varieties of coke, other than those from coal, 
generally are identified by prefixing a word to indicate the source, e.g., 
"petroleum coke". To indicate the process by which a coke is manufactured, 
a prefix also is often used, e.g., "beehive coke". 
High temperature coke can be used in this invention. As is known to those 
skilled in the art, this coke can be prepared from bituminous coal. Most 
of this type of coke is made in slot-type recovery ovens. In general, this 
type of coke contains from about 0.6 to about 1.4 weight percent of 
volatile matter and has an apparent specific gravity of from about 0.8 to 
about 0.99. 
Foundry coke can also be used in this invention. In general, the volatile 
matter in this type of coke is less than about 2 weight percent. 
Low temperature coke and medium temperature coke can also be used in this 
invention. 
Pitch coke can be used in this invention. Pitch coke is made from coal-tar 
pitch; it has about 1.0 percent volatile matter, and it generally contains 
less than 0.5 percent sulfur. 
Petroleum coke can be used in this invention. There are at least two types 
of petroleum coke: delayed coke and fluid coke. Delayed coke generally 
contains from about 8 to about 18 weight percent volatile matter, has a 
grindability index of from about 40 to about 60, and has a true density of 
from about 1.28 to about 1.42 grams per milliliter. Fluid coke generally 
contains from about 3.7 to about 7.0 weight percent of volatile matter, 
has a grindability index of from about 20 to about 30, and has a true 
density of from about 1.5 to about 1.6 grams per milliliter. 
In another preferred embodiment, the carbonaceous solid material is char. 
Char is the non-agglomerated, non-fusible residue from the thermal 
treatment of solid carbonaceous materials. Coal char is obtained as a 
residue or a coproduct from low-temperature carbonization processes; such 
a char typically contains from about 1 to about 5 weight percent of 
volatile matter. 
In another preferred embodiment, the carbonaceous material is charcoal. 
Charcoal is the residue remaining after the destructive distillation of 
wood. 
In yet another embodiment, the carbonaceous material is solvent refined 
coal. 
In general, any carbonaceous fuel can be used as the solid carbonaceous 
material in this invention. 
Mixtures of carbonaceous solids also can be used. By way of illustration 
and not limitation, one can use a mixture of at least one coarse 
carbonaceous fraction which contains less than about 30 weight percent of 
volatilizable hydrocarbons (such as, e.g., anthracite or low volatile 
bituminous coal) and at least one fine carbonaceous fraction which 
contains more than about 35 weight percent of volatilizable hydrocarbons 
(such as, e.g., lignite or high volatile bituminous coal). One can use a 
mixture of two or more of said coarse carbonaceous fractions and one of 
said fine fractions, one of said coarse carbonaceous fractions and two or 
more of said fine fractions, or two or more of said coarse carbonaceous 
fractions and two or more of said fine fractions. In this embodiment, the 
grinding mixture is preferably comprised of from about 2 to about 50 
weight percent of solid carbonaceous material which has a median particle 
size of from about 0.5 to about 40 microns and from about 50 to about 98 
weight percent of solid carbonaceous material which has a median particle 
size in excess of 40 microns. 
In one embodiment of this invention, the grinding mixture is comprised of 
at least two consists of carbonaceous material. As used in this 
specification, and in the prior art, the term "consist" means the particle 
size distribution of the solid phase of the carbonaceous material/fluid 
slurry. For example, in the prior art, the term "8 mesh.times.0", when 
used with reference to a coal-water slurry, indicates coal with a graded 
size, or consist, of coal particles distributed in the range of 8 mesh and 
zero, or 2360 microns.times.zero microns. Similarly, the term "about 1180 
microns.times.0.05 microns" indicates coal with a nominally measurable 
graded size, or "consist", of coal particles distributed in the range of 
from about 1180 microns to a measurable colloidal size, e.g., at least 
about 0.05 microns. The term "about 1180 microns" is nominally equivalent 
to a U.S. Series 16 mesh sieve, substantially as defined in "Handbook of 
Chemistry and Physics", 54th Edition, 1973-1974, CRC Press, Cleveland, 
Ohio, page 143, "Standard Test Sieves (wire cloth)", the disclosure of 
which is hereby incorporated by reference into this specification. Unless 
otherwise stated in this specification, the weight of carbonaceous 
material is on a moisture-free or "dry basis" herein. Thus, e.g., the 
"solids" in as-mined carbonaceous material include, e.g., carbonaceous 
material and ash. Thus, there is a considerable amount of bound water in 
coal as mined; the volume of this water in the coal is not included in the 
solids weight in order to calculate the volume percent of "dry solids" in 
the grinding mixture used in the process of this invention. Thus, as used 
herein, the term "dry basis" refers to coal (and/or other carbonaceous 
material) which is substantially free of carrier liquid. Carbonaceous 
material is considered to be dry after it has been air dried by being 
exposed to air at a temperature of at least 70 degrees Fahrenheit and a 
relative humidity of less than humidity of less than 50 percent for at 
least 24 hours. 
In one preferred embodiment of this invention, at least two consists of 
carbonaceous material are mixed with carrier fluid to prepare the grinding 
mixture. Both of said consists of carbonaceous material can be produced by 
wet grinding; thus, e.g., one of the consists can be produced by grinding 
coal at a high solids content (60-82 volume percent) in the presence of 
water and optionally, surfactant, the second of the consists can be 
produced by grinding coal at a lower solids content (30-60 volume percent) 
in a ball mill or a stirred ball mill, and the first and the second coal 
consists can be ground together with each other (and, optionally, with one 
or more additional consists produced by wet and/or dry grinding) at a 
solids content of from about 60 to about 82 volume percent in the optional 
presence of from about 0.01 to about 4.0 weight percent of dispersant and 
water. Alternatively, both of said consists of carbonaceous material can 
be produced by dry grinding; thus, e.g., one of the consists can be 
prepared by grinding one pulverized coal (i.e., coal which has been milled 
or ground to a consist of about 20 mesh by 0) in, e.g., a ring roller 
mill, a second or more of the consists can be prepared by dry grinding a 
second pulverized coal in, e.g., a micronizer fluid energy (jet) mill, and 
the two ground dry fractions are then blended in a blending tank at a 
solids concentration of from 60-90 volume percent with water and, 
optionally, 0.01 to 4.0 weight percent of dispersant at a high shear 
stress in a mixer such as a Greerco in-line mixer. 
Alternatively, at least one of said consists can be produced by wet 
grinding, and at least one of said consists can be produced by dry 
grinding; thus, e.g., one of the consists can be produced by wet grinding 
coal at a low solids content (30-60 volume percent) in the presence of 
water and, optionally, dispersant, a second of the consists can be 
produced by dry grinding pulverized coal in either a micronizer fluid 
energy (jet) mill, or a ring roller mill, and the consists produced by wet 
and dry grinding are then blended in a blending tank at a solids 
concentration of 60-82 volume percent water and, optionally, 0.01 to 4.0 
weight percent of dispersant at a high shear stress in a mixer such as a 
Greerco in-line mixer. 
Alternatively, one can prepare the grinding mixture by wet grinding (or 
regrinding) slurry comprised of carbonaceous material to produce the fine 
consist for the mixture. Thus, by way of illustration, a fine consist can 
be prepared by regrinding a "final slurry" product at a concentration of 
from about 40 to about 60 weight percent solids (and preferably at from 
about 45 to about 55 weight percent of solids) in, e.g., a stirred ball 
mill until the median particle size of the slurry is from about 4 to about 
20 microns. The coarse consist can be produced by dry crushing (in, e.g., 
a roll crusher, a gyratory crusher, a cage mill, etc.) the carbonaceous 
material to a nominal 3/8".times.0 size so that the median particle size 
of the coarse fraction exceeds 40 microns. The coarse and fine fractions 
can then be combined with each other, carrier liquid, and dispersing agent 
to produce a grinding mixture comprised of from about 60 to about 82 
volume percent of carbonaceous material, from about 18 to about 40 volume 
percent of carrier liquid, and from about 0.01 to about 4.0 weight percent 
of dispersion dispersing agent. 
The fine consist in this particular embodiment can alternatively be made by 
regrinding a dry pulverized coal at a concentration of from about 40 to 
about 60 weight percent solids until the median particle size of the fine 
consist is from about 4 to about 20 microns. 
The aforementioned processes are all illustrated in FIG. 2. 
It will be apparent to those skilled in the art that there are many other 
arrangements wherein two consists of carbonaceous material can be mixed 
with carrier liquid to produce the grinding mixture; they are intended to 
be within the scope of the invention. 
The solid carbonaceous material in the preferred grinding mixture consists 
essentially of at least one fine solid carbonaceous material and at least 
one coarse solid carbonaceous material. From about 2 to about 50 weight 
percent of the solid carbonaceous material in the grinding mixture can be 
comprised of fine solid carbonaceous material with a median particle size 
of from about 0.5 to about 40 microns; it is preferred that from about 4 
to about 40 weight percent of the solid carbonaceous material in the 
grinding mixture be comprised of fine solid carbonaceous material with a 
median particle size of from about 1 to about 30 microns; and it is even 
more preferred that from about 6 to about 30 weight percent of the solid 
carbonaceous material in the grinding mixture be comprised of fine solid 
carbonaceous material with a median particle size of from about 2 to about 
20 microns. From about 50 to about 98 weight percent of the solid 
carbonaceous material in the grinding mixture can be comprised of coarse 
solid carbonaceous material with a median particle size greater than 40 
microns. 
The preferred grinding mixture can contain one fine carbonaceous solid 
fraction or several fine carbonaceous solid fractions, which may be the 
same or different carbonaceous materials; regardless of whether one or 
several such fine fractions are present in this grinding mixture, from 
about 2 to about 50 weight percent of the solid carbonaceous material in 
this grinding mixture has a median particle size of from about 0.5 to 
about 40 microns. 
The preferred grinding mixture can contain one coarse carbonaceous solid 
fraction or several coarse carbonaceous solid fractions, which may be the 
same or different carbonaceous materials; regardless of whether one or 
several such coarse fractions are present in this grinding mixture, from 
about 50 to about 98 weight percent of the solid carbonaceous material in 
this grinding mixture has a median particle size greater than about 40 
microns. It is preferred that the grinding mixture be comprised of from 
about 60 to about 96 weight percent of said coarse solid carbonaceous 
material, and it is more preferred that said grinding mixture be comprised 
of from about 70 to about 94 weight percent of said coarse solid 
carbonaceous material. 
The grinding mixture can be comprised of discrete fine fraction(s) and 
coarse fraction(s) of solid carbonaceous material. Alternatively, the 
grinding mixture can be comprised of a single fraction of carbonaceous 
material, which was produced by mixing said coarse fraction(s) and said 
fine fraction(s). As long as a particle size analysis of the solid 
carbonaceous material in the preferred grinding mixture reveals that from 
about 2 to about 50 weight percent of said material has a median particle 
size of from about 0.5 to about 40 microns, and that from about 50 to 
about 98 weight percent of said material has a median particle size 
greater than 40 microns, then the consists of carbonaceous material are 
suitable for use in the preferred grinding mixture of this invention. The 
particle size analysis of the carbonaceous material will show substantial 
undulation at one or more points in the entire CPFT plot where two or more 
size distributions have obviously merged. 
The carbonaceous solid is preferably mixed with from about 0.01 to about 
4.0 weight percent (based upon dry weight of carbonaceous solid) of 
dispersing agent to produce said grinding mixture. In the case where at 
least two consists of carbonaceous solid material are mixed with liquid, 
(1) both of the consists can be dry ground and mixed with liquid and 
dispersant, (2) the dispersant can be mixed with the liquid, and the dry 
ground consists can be mixed with the liquid-dispersant mixture; (3) one 
of the consists can be dry ground, a second of the consists can be wet 
ground with part or all of the dispersant, and the ground consists can be 
mixed with the balance of the liquid and dispersant which was not 
theretofore mixed with the consists, or (4) some or all of the dispersant 
can be wet ground with one or both of the consists, and the ground 
consists can then be mixed with the liquid and the balance of the 
dispersant which was not therefore mixed with the consists; (5) one or 
more consists can be wet ground with no dispersant and insufficient total 
water and then blended with dispersant and the balance of the water and/or 
other consist blends. 
The grinding mixture used preferably contains from about 60 to about 82 
volume percent of one or more carbonaceous solid materials. It is 
preferred that said grinding mixture contain from about 64 to about 81 
volume percent of said carbonaceous solid material. In a more preferred 
embodiment, the grinding mixture contains from about 75 to about 80 volume 
percent of said solid carbonaceous material. 
The grinding mixture used generally has a pH of from about 5 to about 12. 
It is preferred that the pH of the grinding mixture be from about 7 to 
about 11. 
The grinding mixture used is comprised of one or more liquids. As used in 
this specification, the term liquid refers to a substance which undergoes 
continuous deformation under a shearing stress. The liquid used in the 
grinding mixture preferably performs at least two functions--it fills the 
interstitial pores of the carbonaceous solid material, and it provides the 
vehicle for separation of the particles of the carbonaceous solid material 
to minimize collisions between said particles; thus, the preferred liquid 
is a carrier liquid. 
By way of illustration and not limitation, some of the liquids which can be 
used in the slurry pumped in the process of this invention include water; 
waste industrial solvents such as, e.g., effluents from waste disposal 
plants, contaminated waste water containing hydrocarbons from e.g., 
oil-separation processes, and the like; aromatic and aliphatic alcohols 
containing 1-10 carbon atoms, such as methanol, propanol, ethanol, 
butanol, phenol, mixtures thereof, and the like; pine oil; petroleum 
liquids such as, e.g., number 2 fuel oil, number 4 fuel oil, number 6 fuel 
oil, gasoline, naphtha, mixtures thereof, and the like; hydrocarbon 
solvents such as, e.g., benzene, toluene, xylene, kerosene, and 
derivatives thereof; acetone; aniline; anisole; halobenzenes such as; 
e.g., bromobenzene and chlorobenzene; nitrobenzene; carbon tetrachloride; 
chloroform; cyclohexane; n-decane; dodecane; 1,1,2,2-tetrachloroethane; 
ethyl bromide; 1,2-dichloroethylene; tetrachloroethylene; 
trichloroethylene; ethylene chloride; ethyl ether; ethyl iodide; glycol; 
n-hendecane; n-heptane; 1-heptanol; 1-hexanol; methylene halides such as, 
e.g., methylene chloride, methylene bromide, and methylene iodide; 
n-octadecane; n-octane; 1-octanol; n-pentadecane pentanol; and the like. 
The aforementioned list is merely illustrative, and those skilled in the 
art will recognize that many other liquids can be used. 
In one preferred embodiment, the liquid used is carrier water. As used in 
this specification, the term "carrier water" means the bulk of free water 
dispersed between the carbonaceous particles and contiguous to the bound 
layers on the particles, and it is to be distinguished from bound water. 
The term "bound water" means water retained in the "bound water layer", as 
defined and illustrated in Kirk-Othmer, Encyclopedia of Chemical 
Technology, 2d Edition, Vol. 22, pages 90-97 (at p. 91). 
When the liquid mixed with the carbonaceous solid is water or is comprised 
of from about 5 to about 99 weight percent of water, it is preferred that 
the temperature of the solids-liquid mixture be maintained at from ambient 
to about 99 degrees centigrade during mixing to insure that the water does 
not substantially vaporize. 
When water is added to a carbonaceous powder comprised of finely divided 
particles, and if the water "wets" the powder, a surface water film is 
adsorbed on each particle which is known to be structurally different from 
the surrounding "free" or bulk water, in that the film may be described as 
"semi-rigid", or "bound water film". Depending on the fundamental 
electrical potential of the surface, this "semi-rigid" or bound water film 
may be of several molecules thickness. 
Mixtures of at least two liquids can be used in the grinding mixture. Thus, 
by way of illustration and not limitation, one may use mixtures of water 
and ethanol, water and petroleum liquids, and the like. One can use 
mixtures comprised of from about 1 to about 99 volume percent of alcohol 
and from about 99 to about 1 volume percent of water. In one preferred 
embodiment, the mixture is comprised of from about 1 to about 15 volume 
percent of alcohol with the remainder of the liquid consisting essentially 
of water. It is preferred that the alcohol be liquid and monohydric and 
that it contain from about 1 to about 10 carbon atoms. Suitable monohydric 
alcohols are listed on page 265 of Fieser and Fieser's "Advanced Organic 
Chemistry" (Reinhold, N.Y., 1961), the disclosure of which is hereby 
incorporated by reference into this specification. 
In one preferred embodiment, the grinding mixture is comprised of at least 
about 60 volume percent of carbonaceous solid material and from about 18 
to about 40 volume percent of carrier liquid. In one aspect of this 
embodiment, at least about 90 weight percent of the carrier liquid is 
water and less than about 10 weight percent of the carrier liquid is 
petroleum liquid. In this aspect, it is preferred that the petroleum 
liquid be selected from the group consisting of naphtha, high gas oil, low 
gas oil, catalytic cracked recycle oil, mixtures thereof, and other 
similar petroleum products. Vegetable oils, such as corn, bean, or pine 
oil, may also be used to replace part or all of the petroleum liquid. 
The grinding mixture is preferably comprised of from about 18 to about 40 
volume percent of one or more carrier liquids. It is preferred that the 
grinding mixture contain from about 19 to about 36 volume percent of one 
or more carrier liquids. In the most preferred embodiment, the grinding 
mixture is comprised of from 20 to about 25 volume percent of one or more 
carrier liquids. 
In addition to the aforementioned carbonaceous solids, carrier liquid(s), 
and dispersant, the grinding mixture also can contain from about 0 to 
about 10 volume percent of other additives sometimes present in coal-water 
slurries such as, e.g., inorganic electrolytes, etc. 
The grinding mixture preferably contains from about 0.01 to about 4.0 
weight percent of dispersing agent, based upon the weight of dry 
carbonaceous solid material. In one embodiment, however, no dispersing 
agent is present in the grinding mixture. The grinding mixture can contain 
the amount and type of dispersing agent which is most effective for it. 
Means for determining the identity and amount of the most effective 
dispersing agent for a given mixture will be described below for a 
coal-water mixture, it being understood that the technique described is 
applicable to other mixtures such as, e.g., coke-water, graphite-water, 
etc. 
In general, for any given system, the identity of effective dispersing 
agents can be determined by measuring the effects of the dispersant upon 
the system at a given dispersant concentration; viscosity versus shear 
rate of the stirred coal-water slurry is measured while titrating with 
increasing amounts of the dispersing agent, and the point at which the 
slurry viscosity ceases to decrease is noted. For any given dispersant(s), 
and system, the most effective concentration is the one which gives the 
minimum viscosity under a given set of test conditions, and the efficiency 
of different dispersants can be compared by testing them with a given 
system under comparable concentration and test conditions. Thus, for 
example, one can grind a sample of coal in a laboratory size ball mill 
with porcelain or steel balls in water at 50 weight percent solids, e.g., 
for 24 hours or until all of the particles in the coal are less than 10 
microns in size; other grinding devices known to those skilled in the art 
may also be used such as vibroenergy mills, stirred ball mills, or fluid 
energy mills. Small samples (about 500 milliliters apiece) of the system 
can then be deflocculated by adding various dispersing agents to the 
samples dry or preferably in solution dropwise, blending the mixture at 
any consistent blending energy (which may be gentle as mixing by hand, or 
at very high shear energy which will improve dispersion), and then 
measuring the viscosity at some constant shear rate by, e.g., using a 
Brookfield RVT viscometer at 100 revolutions per minute. The dispersing 
agent (or combination of dispersing agents) which is found to produce the 
lowest viscosity for the system at a given shear rate and dispersing 
agent(s) concentration is the most effective for those conditions. This 
technique is described in detail in my U.S. Pat. No. 4,282,006, the 
disclosure of which is hereby incorporated herein by reference. 
FIG. 1 illustrates one means of evaluating the effectiveness of surfactants 
for any given solid material. The curves of FIG. 1 represent data obtained 
using both a purported nonionic polymer CW-11 made by the Diamond Shamrock 
Process Chemicals Co. and an anionic lignosulfonate Polyfon-F made by 
Westvaco, Inc., adsorbed on an Australian coal. The fine coal ground to 
about 100% finer than 10 microns is slurried in distilled water at 0.01 
weight percent solids. Aliquots are placed in test tubes, and increasing 
amounts of any candidate surfactant are added to each test tube. The test 
tube samples are thoroughly mixed and inserted into a sampler carousel. 
The Pen Kem System 3000 Electrophoretic Mobility Analyzer automatically 
and sequentially samples each test tube and measures the electrophoretic 
mobility of the coal particles and the specific conductance of the carrier 
liquid; pH can also be measured on each sample. In FIG. 1 the left 
ordinate gives the calculated zeta potential of the particles in 
millivolts, the right ordinate gives the specific conductance in micromhos 
of the carrier liquid. These variables are both measured as a function of 
the percent addition of each surfactant on a dry coal basis which is 
plotted on the abscissa. FIG. 1 shows that the purported nonionic CW-11 
surfactant does have some anionic character. CW-11 has a zeta potential of 
-50 mv at 300% addition at 0.01% dry coal. Polyfon-F has a zeta potential 
of -55 mv at 200% addition on 0.01% dry coal. Furthermore, the specific 
conductance of the Polyfon-F at -55 m.v. zeta potential is greater than 
CW-11 at -50 m.v. These data establish Polyfon-F as a more chemically 
effective surfactant for use on this particular Australian coal. 
The amount of dispersing agents which can be used will vary, depending upon 
such factors as the concentration of the coal in the slurry, the particle 
size and particle size distribution, the amount of ash minerals (i.e. 
clays and other minerals present), the temperature of the slurry, the pH, 
the original zeta potential of the particles, and the identity of the 
dispersing agent(s) and its concentration. In general, the dispersing 
agent preferably is present in the slurry, at from 0.01 to 4.0 weight 
percent based on the weight of dry coal. Procedurally, in determining the 
amount of a specific dispersing agent needed, a series of measurements can 
be made of viscosities versus shear rates versus zeta potential for a 
series of solids-liquid slurries containing a range of amounts of a 
particular dispersing agent for a constant amount of solids-liquid slurry. 
The data can be plotted and used as a guide to the optimum quantities of 
that agent to use to obtain near maximum or maximum zeta potential for 
that system. The coordinate of the chart at which the viscosity and/or 
zeta potential is not changed significantly by adding more agent is 
selected as an indication of the optimum quantity at maximum zeta 
potential, and the amount is read from the base line of the chart. The 
viscosity and amount read from the titration chart is then compared with 
an equivalent chart showing a correlation between viscosity, amount, and 
maximum zeta potential. As amount of electrolyte and/or dispersing 
agent(s) required to provide a maximum or near maximum zeta potential and 
a selected viscosity can then be used to make a solids-liquid slurry. 
Any dispersing agent which disperses the carbonaceous particles in the 
water can be used. As is known to those skilled in the art, the dispersing 
agent can be inorganic. Thus, for example, sodium hydroxide can be used 
with some carbonaceous materials. The dispersing agent can be, and 
preferably is, organic, i.e., it contains carbon. The dispersing agent is 
preferably an anionic organic surfactant. 
It is preferred that the dispersing agent used be an organic compound which 
encompasses in the same molecule two dissimilar structural groups, e.g., a 
water soluble moiety, and a water insoluble moiety. It is preferred that 
said dispersing agent be a surfactant. The term "surface-active agent", or 
"surfactant", as used herein indicates any substance that alters energy 
relationships at interfaces, and, in particular, a synthetic or natural 
organic compound displaying surface activity including wetting agents, 
detergents, penetrants, spreaders, dispersing agents, foaming agents, etc. 
The surfactant used is preferably an organic surfactant selected from the 
group consisting of anionic surfactants, nonionic surfactants, cationic 
surfactants, and amphoteric surfactants. It is preferred that the 
surfactant be either anionic or cationic. In the most preferred 
embodiment, the surfactant is anionic. 
It is preferred that the molecular weight of the surfactant used be at 
least about 200. As used herein, the term "molecular weight" refers to the 
sum of the atomic weights of all the atoms in a molecule. 
In one preferred embodiment, the surfactant is anionic and its solubilizing 
group(s) is selected from the group consisting of a carboxylate group, a 
sulfonate group, a sulfate group, a phosphate group, and mixtures thereof. 
By way of illustration, one of these preferred anionic surfactants is a 
polyacrylate having the general formula: 
##STR1## 
wherein n is a whole number of at least 3 and M is selected from the group 
consisting of hydrogen, sodium, potassium, and ammonium. 
In another preferred embodiment, the surfactant is cationic and its 
solubilizing group(s) is selected from the group consisting of a primary 
amine group, a secondary amine group, a tertiary amine group, a quaternary 
ammonium group and mixtures thereof. 
In yet another embodiment, the surfactant is amphoteric. In this 
embodiment, the surfactant has at least one solubilizing group selected 
from the group consisting of a carboxylate group, a sulfonate group, a 
sulfate group, a phosphate group, and mixtures thereof; and the surfactant 
also has at least one solubilizing group selected from the group 
consisting of a primary amine group, a secondary amine group, a tertiary 
amine group, a quaternary ammonium group, and mixtures thereof. 
In one of the more preferred embodiments, the surfactant used is comprised 
of at least about 85 weight percent of a structural unit of the formula: 
##STR2## 
wherein R.sub.1 and R.sub.2 are independently selected from the group 
consisting of alkyl of from about 1 to about 6 carbon atoms and hydrogen; 
a, b, c, and d are integers independently selected from the group 
consisting of 0, 1, 2, 3, 4, 5, 6, 7, and 8, and X.sub.2 and X.sub.3 are 
independently selected from the group consisting of a carboxylate group, a 
sulfonate group, a sulfate group, a phosphate group, a nitro group, a halo 
group selected from the group consisting of chloro, bromo, fluoro, and 
iodo, --CN, an alkoxy group containing from 1 to about 6 carbon atoms, and 
a group of the formula --R.sub.3 OR.sub.4 wherein R.sub.3 and R.sub.4 are 
an alkyl containing from about 1 to about 3 carbon atoms. The starting 
materials which can be used to prepare these surfactants are well known to 
those skilled in the art and include, e.g., naphthalene--.alpha. sulfonic 
acid (dihydrate), naphthalene-.beta.-sulfonic acid (monohydrate), 
.alpha.-nitronaphthalene, .beta.-nitronaphthalene, .alpha.-naphthylamine, 
.beta.-naphthylamine, .alpha.-naphthol, .beta.-naphthol, .alpha.-naphthoic 
acid, .beta.-naphthoic acid, .alpha.-chloronaphthalene, 
.alpha.-bromonaphthalene, .beta.-bromonaphthalene, 
.beta.-chloronaphthalene, .alpha.-naphthonitrile, .beta.-naphthonitrile, 
1,5-dinitronaphthalene, 1,8-dinitronaphthalene, .beta.-methylnaphthalene, 
1-nitro-2-methylnaphthalene, 2-methylnaphthalene-6-sulfonic acid, 
2,6-dimethylnaphthalene, .beta.-6-methylnaphtholpropionic acid, 
1,6-dibromo-2-naphthol, 6-bromo-2-naphthol, 1,6-dibromonaphthalene, 
6-bromo-2-naphthol, and the like. Again, it is preferred that at least one 
of the atoms in this surfactant be an alkali metal selected from the group 
consisting of sodium, potassium, ammonium, and mixtures thereof. One of 
the most preferred surfactants from this group is the alkali metal salt of 
a condensed mononaphthalene sulfonic acid. This acid, whose preparation is 
described in U.S. Pat. No. 3,067,243 (the disclosure of which is hereby 
incorporated by reference into this specification), can be prepared by 
sulfonating naphthalene with sulfuric acid, condensing the sulfonated 
naphthalene with formaldehyde, and then neutralizing the condensate so 
obtained with sodium hydroxide. This alkali or NH.sub.4.spsb.+ metal salt 
of a condensed mono naphthalene sulfonic acid is comprised of at least 
about 85 weight percent of a repeating structural unit of the formula: 
##STR3## 
wherein M is an alkali metal selected from the group consisting of sodium, 
potassium, and ammonium and a is an integer of from 1 to 8. Comparable 
compounds with a benzene rather than naphthalene nucleus also can be used. 
Examples of anionic organic surfactants which have been found particularly 
advantageous are also described below. In some cases, mixtures of two or 
more of these surfactants beneficially can be used. 
Some of the surfactants sold by the Diamond Shamrock Chemical Company of 
Morristown, N.J. can be used in this invention. Thus, by way of example, 
one can use surfactants such as Lomar D (the sodium salt of a condensed 
mono naphthalene sulfonic acid), Lomar PW (sodium neutralized naphthalene 
sulfonic acid), Lomar PWA (ammonia salt of a condensed mono naphthalene 
sulfonic acid), A23, Nopcosperse VFG (condensed alkyl naphthalene 
sulfonate), and Nopcosperse VEO (polymerized alkyl naphthalene sulfonate). 
Some of the surfactants sold by the R. T. Vanderbilt Company of Norwalk, 
Conn. can be used in this invention. Thus, by way of example, one can use 
Darvan #1 (sodium naphthalene sulfonic acid formaldehyde), Darvan #2 
(sodium salts of polymerized substituted benzoid alkyl sulfonic acids), 
and Darvan #6 (sodium salts of polymerized alkyl naphthalene sulfonic 
acid). 
Some of the surfactants sold by the Westvaco-Polychemicals, Charleston 
Heights, S.C. can be used in this invention. Thus, for example, one can 
use Reax 88B (sodium salt of a chemically modified low molecular 
weight-kraft lignin polymer solubilized by 4 sulfonate groups), Reax 15B 
(sodium salt of sulfonated modified kraft lignin), Reax 100M (reaction 
product of selected modified kraft lignins with a high sulfonic acid group 
content), and Polyfon 0 (sugar-free, sodium-based sulfonates of Kraft 
lignin). 
Some of the surfactants sold by the WR Grace & Co., Organic Chemicals Div., 
Lexington, Maine can be used in this invention. Thus, by way of 
illustration, one can use Daxad 11, 11G, 15, or 19 (sodium salts of 
polymerized alkyl naphthalene sulfonic acids), Daxad 30 or 31 (sodium salt 
of a carboxylated polyelectrolyte), or Daxad 32 (ammonium salt of a 
carboxylated polyelectrolyte). 
Some of the surfactants sold by the Rohm & Haas Company of Philadelphia, 
Pa. can be used in this invention. Thus, for example, one can use, Triton 
X-100 (octylphenoxy polyethoxy ethanol), Triton N-101 (nonylphenoxy 
polyethoxy ethanol), Tamol 731 (sodium salt of polymeric carboxylic acid), 
Tamol 850 (sodium salt of polymeric carboxylic acid), and Tamol SN (sodium 
salt of condensed naphthalene sulfonic acid). 
Some of the surfactants produced by the Hamblet & Hayes Co. of Salem, Mass. 
can be used in this invention. Thus, e.g., one can use Tek Tan ND 
(condensed naphthalene sulfonate). 
Some of the surfactants made by the National Starch and Chemical Corp. of 
Bridgwater, N.J. can be used in this invention. Thus, one can use Versa TL 
70 (an anionic polyelectrolyte of sodium polystyrene). 
Some of the surfactants made by the Thompson-Hayward Chemical Co. of Kansas 
City, Kans. also can be used in this invention. Thus, for example, one can 
use T-DET N-100 (nonylphenol-100 mole ethylene oxide adduct), T-DET N-50 
(nonylphenol-50 mole ethylene oxide adduct), T-DET N-14 (nonylphenol-14 
mole ethylene oxide adduct), T-DET N-9.5 (nonylphenol-9.5 mole ethylene 
oxide adduct), T-DET C-40 (polyethoxylated castor oil with 40 moles of 
ethylene oxide), and the like. 
Renex 30, a polyoxyethylene (12) tridecyl ether manufactured by the ICI 
Corp. of Wilmington, Del., also can be used in this invention. 
Some of the Dupanol surfactants manufactured by the E. I. duPont De Nemours 
& Co. of Wilmington, Del. also can be used in this invention. Thus, one 
can use Dupanol WA and Dupanol WAQ (both sodium lauryl sulfate). 
Some of the surfactants made by the Scher Chemicals, Inc. of Clifton, N.J. 
also can be used in this invention. Thus, one can use cocamidopropyl 
betaine. 
One class of surfactants which can beneficially be used in this invention 
are the polyalkyleneoxide nonionic surfactants having a hydrophobic 
portion and a hydrophilic portion, wherein the hydrophilic portion 
comprises at least about 100 units of ethylene oxide. These surfactants 
are disclosed in U.S. Pat. No. 4,358,293, the disclosure of which patent 
is hereby incorporated by reference into this specification. 
The polyalkyleneoxide nonionic surfactants suitable for use in the 
invention include the glycol ethers of alkylated phenols having a 
molecular weight of at least about 4,000 of the general formula: 
##STR4## 
wherein R is substituted or unsubstituted alkyl of from 1 to 18 carbon 
atoms, preferably 9 carbon atoms; substituted or unsubstituted aryl, or an 
amino group, and n is an integer of at least about 100. The substituents 
of the alkyl and aryl radicals can include halogen, hydroxy, and the like. 
Other suitable nonionic surfactants are the 
poly(oxyethylene)poly(oxypropylene)-poly(oxyethylene) or as otherwise 
described propoxylated, ethoxylated propylene glycol nonionic surfactant 
block polymers having a molecular weight of at least about 6,000 of the 
general formula: 
EQU HO(CH.sub.2 CH.sub.2 O).sub.a [CH(CH.sub.3)CH.sub.2 O].sub.b (CH.sub.2 
CH.sub.2 O).sub.c H 
wherein a, b and c are whole integers and wherein a and c total at least 
about 100. 
Still other polyalkyleneoxide nonionic surfactants suitable for use in the 
invention are the block polymers of ethylene and propylene oxide derived 
from nitrogen-containing compositions such as ethtylene diamine and having 
a molecular weight of at least about 14,000 of the general formula: 
##STR5## 
wherein R.sub.1 is an alkylene radical having 2 to 5 carbon atoms 
preferably 2; R.sub.2 is alkylene radical having 3 to 5 carbon atoms, 
preferably 3; a, b, c, d, e, f, g and h are whole integers; and e, f, g 
and h total at least about 100. 
One of the preferred surfactants is 
##STR6## 
wherein M is alkali metal (and most preferably is sodium) and n is less 
than 200 and, preferably, less than 100. 
While, in one embodiment, the use of the sodium, potassium, or ammonium 
salts of condensed mononaphthalene sulfonic acid is preferred, it is to be 
understood that the condensed mononaphthalene sulfonic acid can be used 
with the addition of sodium, potassium, or ammonium alkali to form the 
corresponding alkali metal salt of that acid in situ. 
Yet another of the surfactants which can be used in this invention is an 
anionic, alkylaryl sulfonate which is liquid and has an HLB number of from 
about 8.0 to about 15.0. 
Yet another preferred surfactant is a lignin-based dispersing agent which 
is water soluble and which contains a sulfite lignin which ranges in 
molecular weight from about 1,000 to about 50,000 and whose basic lignin 
unit is a substituted phenylpropane. This lignin can be generated by the 
acid sulfite wood pulping process. 
Yet another preferred surfactant is a lignin-based dispersing agent which 
is water-soluble and which contains an alkali lignin isolated from sulfate 
pulping black liquor generated in the alkaline sulfate wood pulping 
process. 
Yet another class of preferred surfactant is a complex polymerized organic 
salt of sulfonic acids of the alkylaryl type such as, e.g., sodium 
naphthalene sulfonic acid formaldehyde, sodium salts of polymerized alkyl 
naphthalene sulfonic acid, and the like. 
Another preferred class of surfactants is the lignosulfonates. These 
lignosulfonates have an equivalent weight of from about 100 to about 350, 
contain from about 2 to about 60 phenyl propane units (and, preferably, 
from about 3 to 50 phenyl propane units), and are made up of cross-linked 
polyaromatic chains. Some of the preferred lignosulfonates include those 
listed on page 293 of McCutcheon's "Emulsifiers and Detergents), North 
American Edition (McCutcheon Division, MC Publishing Co., Glen Rock, N.J. 
1981) and in the other portions of McCutcheon's which describes said 
lignosulfonates, the disclosure of which is hereby incorporated by 
reference into this specification. In one preferred embodiment, the 
lignosulfonate surfactant contains from about 0.5 to about 8.0 sulfonate 
groups. In this preferred embodiment, one species has 0.5 sulfonate 
groups, one has one sulfonate group, one has two sulfonate groups, and one 
has four sulfonate groups, and one has 7.5 sulfonate groups. 
Applicant does not wish to be bound to any particular theory. However, he 
believes that a dispersing agent in a aqueous slurry system might perform 
at least three functions. In the first place, it is believed that a water 
soluble dispersing agent, which also serves as a wetting agent (such as an 
organic surfactant), functions to promote the wettability of the 
carbonaceous particles by water. As used herein, the term "wetting" 
indicates covering or penetrating the carbonaceous particle surface with a 
bound water layer. Such a wetting agent might or might not be needed, 
depending upon the surface chemistry of the particle, its hydrophobicity, 
and the associated electrochemistry of its inherent bound water layers. 
For example, inherent bed moisture, oxidation state of the particle, and 
chemical compounds already present in natural carbonaceous deposits may 
allow wetting of the ground material by added water. 
In the second place, a dispersing agent might function to promote 
deflocculation of carbonaceous particles, preferably in the presence of 
advantageous electrolytes. As used herein, the term "deflocculating" 
indicates dispersion of particles, preferably of colloidal sized 
carbonaceous particles. Thus, e.g., a "deflocculating agent" includes a 
dispersing agent which promotes formation of a colloidal dispersion of 
colloidal sized particles in a solids-liquid slurry. It has been found 
that the presence of large, monovalent cations--such as Na.sup.+, 
Li.sup.+, or K.sup.+ --tend to promote deflocculation of colloidal sized 
carbonaceous particles in a solids-liquid slurry. However, higher valence 
cations--such as Ca.sup.+2, Al.sup.+3, and Mg.sup.+2 --tend to cause said 
particles to flocculate under certain conditions. Consequently, an organic 
anionic surfactant which wets the carbonaceous particles and contains a 
residual Na.sup.+ and/or K.sup.+ and an Li.sup.+ can be a very effective 
deflocculant for the slurry. 
In the third place, in some cases the dispersing agent enhances the 
pumpability of the system. It is believed that this effect occurs because 
of enhancement or inhibition of the bound, or semi-rigid, water layer 
because the dispersing agent provides a cation as a counterion for the 
bound water layer, thereby affecting the yield pseudoplastic index (slope 
of a plot of log viscosity versus log shear rate) of the mass. Preferably, 
the cation provided by the dispersing agent is NH.sub.4.spsb.+, Na.sup.+ 
and/or K.sup.+. Consequently, it is preferred to incorporate an 
advantageous electrolyte, such as an ammonium or alkali metal base, into 
an aqueous slurry to increase deflocculation of the slurry and thus 
improve its yield pseudoplasticity. 
It is preferred that the dispersing agent(s) used in the system provide one 
or more ions to the system. As used in this specification, the term "ion" 
includes an electrically charged atom, an electrically charged radical, or 
an electrically charged molecule. 
In one preferred embodiment, the dispersing agent(s) used in the system 
provides one or more counterions which are of opposite charge to that of 
the surface of the carbonaceous particles. The charge on the surface of 
the carbonaceous particles in water is generally negative, and thus it is 
preferred that said counterions have a positive charge. The most preferred 
positively charged ions are the sodium and potassium cations and the 
ammonium radical. 
In one embodiment it is preferred that the dispersing agent(s) used in the 
system be a polyelectrolyte which, preferably, is organic. As used in this 
specification, the term "polyelectrolyte" indicates a polymer which can be 
changed into a molecule with a number of electrical charges along its 
length. It is preferred that the polyelectrolyte have at least one site on 
each recurring structural unit which, when the polyelectrolyte is in 
aqueous solution, provides electrical charge; and it is more preferred 
that the polyelectrolyte have at least two such sites per recurring 
structural unit. In a preferred embodiment, said sites comprise ionizable 
groups selected from the group consisting of ionizable carboxylate, 
sulfonate, sulfate, and phosphate groups. Suitable polyelectrolytes 
include, e.g., the alkali metal and ammonium salts of polycarboxylic acids 
such as, for instance, polyacrylic acid; the sodium salt of condensed 
naphthalene sulfonic acid; polyacrylamide; and the like. 
In one preferred embodiment, the slurry system contains from about 0.05 to 
about 4.0 weight percent by weight of dry solids in the slurry, of an 
electrolyte which, preferably, is inorganic. As used in this 
specification, the term "electrolyte" refers to a substance that 
dissociates into two or more ions to some extent in water or other polar 
solvent. This substance can be, e.g., an acid, base or salt. 
In a more preferred embodiment, the slurry system is comprised of from 
about 0.05 to about 2.0 weight percent of an inorganic electrolyte. In the 
most preferred embodiment, said system is comprised of from about 0.1 to 
about 0.8 weight percent of said electrolyte. In the most preferred 
embodiment, the system contains from about 0.1 to about 0.5 percent of 
inorganic electrolyte. 
Any of the inorganic electrolytes known to those skilled in the art can be 
used in the coal-water system Thus, by way of illustration and not 
limitation, one can use the ammonia or alkali metal salt of 
hexametaphosphates, pyrophosphates, sulfates, carbonates, hydroxides, and 
halides. Alkaline earth metal hydroxides can be used. Other inorganic 
electrolytes known to those skilled in the art also can be used. 
In one preferred embodiment, the inorganic electrolyte is of the formula 
EQU M.sub.a Z.sub.b 
wherein M is an alkali metal selected from the group consisting of lithium, 
sodium, potassium, rubidium, cesium, and francium; b is the valence of 
metal M; a is the valence of anion Z; and Z is an anion selected from the 
group consisting of hexametaphosphate, pyrophosphate, silicate, sulfate, 
carbonate, hydroxide, and halide anions. It is preferred that Z be 
selected from the group consisting of carbonate, hydroxide, and silicate 
anions. The most preferred electrolytes are selected from the group 
consisting of potassium carbonate, sodium hydroxide, and Na.sub.2 
SiO.sub.3.9H.sub.2 O. 
It is preferred that the slurry system contain both said dispersing 
agent(s) and said inorganic electrolyte(s) and that from about 0.05 to 
about 10.0 parts (by weight) of the inorganic electrolyte are present for 
each part (by weight) of the dispersing agent(s) in the system. 
It is preferred that the total concentration of both the dispersing 
agent(s) and/or the inorganic electrolyte be from 0.05 to 4.0 weight 
percent. 
In one preferred embodiment, the grinding mixture is comprised of 
dispersing agent(s) and inorganic electrolyte agent(s) which, when 
dissolved in water, provide electrically charged ions to the mixture. The 
amount of electrically charged ions preferably present in the mixture 
ranges from about 0.01 to about 2.5 weight percent, based upon weight of 
dry carbonaceous materials and most preferably is from about 0.05 to about 
2.0 weight percent. Said concentration of electrically charged ions can be 
calculated by first calculating the weights of the ions in each of the 
dispersing agent(s) and the electrolyte agent(s), adding said weight(s), 
and then dividing the total ion weight by the weight of the dry coal. 
By way of illustration, in one embodiment 0.75 grams of sodium hydroxide 
and 0.75 grams of sodium decyl benzene sulfonate were added to a mixture 
comprised of 100 grams of dry coal. The weight of the sodium ion provided 
by the caustic was equal to 22/40.times.0.75 grams; and it equals 0.4125 
grams. The weight of the sodium ion provided by the sodium decyl benzene 
sulfonate was equal to 22/294.times.0.75 grams; and it equals 0.0561 
grams. The total weight of the sodium ion provided by both the caustic 
electrolyte and the sulfonate dispersing agent was 0.4686 grams. Thus, the 
slurry contained 0.468 weight percent of sodium ion. 
In one embodiment, the grinding mixture used is dilatant. A discussion of 
dilatant materials appears at page 5-38 of Perry and Chilton's "Chemical 
Engineers' Handbook", Fifth Edition (McGraw-Hill Book Company, New York, 
1973), the disclosure of which is hereby incorporated into this 
specification by reference. In general, as is known to those skilled in 
the art, dilatant materials exhibit rheological behavior opposite to that 
of pseudoplastics; their apparent viscosity increases with increasing 
shear rate. 
Some examples of dilatant materials are starch or mica suspensions in 
water, quicksand, and beach sand. Extensive discussions of dilatant 
suspensions, together with a listing of dilatant systems, are given by 
Bauer and Collins ("Thixotropy and Dilatancy" in Eirich, "Rheology", Vol. 
4, Academic, New York, 1967); Green and Griskey, (Trans. Soc. Rheology 
12(1), 13-25, 27-37, 1968); and Griskey and Green (Am. Inst. Chem. Engrs. 
J., 17, 725-728, 1971). The disclosure of said Bauer et al., Green et al., 
and Griskey et al. references are hereby incorporated by reference into 
this specification. 
It is preferred that the pH of the grinding mixture be from about 5 to 
about 12 and, preferably, from about 7 to about 11. The pH of the grinding 
mixture can be adjusted by means well known to those skilled in the art 
such as, e.g., by adding alkali metal hydroxide (such as sodium hydroxide 
and/or potassium hydroxide) to the grinding mixture until its pH is within 
the target range. 
The grinding mixture can be produced by means well known to those skilled 
in the art. One such means will be described below, it being understood 
that other comparable means also can be used. 
In one process, the grinding mixture is prepared by a process comprising 
the steps of (1) preparing a slurry without fines which slurry contains 
from about 40 to about 60 weight percent of solid carbonaceous material; 
(2) grinding said slurry to a fine grind until the median particle size of 
the carbonaceous particles in the slurry is from about 0.5 to about 40 
microns; (3) crushing dry coal until at least 98 weight percent of its 
particles are smaller than 50 mesh (300 microns), provided that the median 
particle size of the crushed coal exceeds about 40 microns; and (4) 
blending the ground slurry and the crushed coal in specified proportions, 
together with dispersant. 
In the first step of this process, a carbonaceous slurry comprised of from 
about 40 to about 70 volume percent of carbonaceous solid material and 
from about 60 to about 30 volume percent of carrier liquid is prepared; it 
is preferred that the slurry contain from about 35 to about 65 volume 
percent of carbonaceous solid material and from about 65 to about 35 
volume percent of carrier liquid. The slurry can be produced by grinding a 
mixture containing from about 40 to about 70 volume percent of solid 
carbonaceous material and from about 70 to about 40 volume percent of 
carrier liquid. 
In the second step of this process, the slurry from step one of the process 
is fine ground in a fine grinder until the median particle size of its 
particles of solid carbonaceous material is from about 0.5 to about 40 
microns and, preferably, from about 1 to about 30 microns. It is most 
preferred to fine grind the slurry until the median particle size of its 
particles of solid carbonaceous material is from about 2 to about 20 
microns. The slurry can be fine ground by means well known to those 
skilled in the art. Thus, by way of example, the slurry can be fine ground 
in a stirred ball mill, a colloid mill, a vibratory mill, etc. 
In the third step of this process, dry carbonaceous material is separately 
ground until its median particle size is greater than about 40 microns and 
about 98 percent of its particles are smaller than 3/8 inch. One may start 
with any size dry coal in this step and grind it. 
In the fourth step of this process, the fine and coarse carbonaceous 
fractions are mixed until a grinding mixture with the desired composition 
is obtained. 
6. (b). Preparing the carbonaceous slurry with the grinding mixture. 
As indicated above, the aforementioned grinding mixture can be provided by 
mixing solid carbonaceous material, carrier liquid, and dispersing agent. 
Thereafter, the grinding mixture can be wet ground until a slurry with 
specified properties is produced. Thus, in general, the grinding can be 
continued to produce a stable, solids-liquid slurry comprising a consist 
of finely-divided particles of solid carbonaceous material dispersed in 
said liquid, wherein: 
(a) said slurry is comprised of at least about 60 volume percent of said 
solid carbonaceous material (dry basis), less than about 40 volume percent 
of said liquid, and from about 0.01 to about 4.0 weight percent (based on 
weight of dry solid carbonaceous material) of dispersing agent; 
(b) said slurry has a yield stress of from about 3 to about 18 Pascals and 
a Brookfield viscosity at a solids content of 70 volume percent, ambient 
temperature, ambient pressure, and a shear rate of 100 revolutions per 
minute of less than 5,000 centipoise; 
(c) said consist has a specific surface area of from about 0.8 to about 4.0 
square meters per cubic centimeter and an interstitial porosity of less 
than 20 volume percent; 
(d) from about 5 to about 70 volume percent of said particles of said 
carbonaceous material are of colloidal size, being smaller than about 3 
microns; 
(e) said consist of finely-divided particles of solid carbonaceous material 
has a particle size distribution substantially in accordance with the 
following formula: 
##EQU1## 
wherein: 1. CPFT is the cumulative percent of said solid carbonaceous 
material finer than a certain specified particle size D, in volume 
percent; 
2. k is the number of component distributions in the consist and is at 
least 1; 
3. X.sub.j is the fractional amount of the component j in the consist, is 
less than or equal to 1.0, and the sum of all of the X.sub.j 's in the 
consist is 1.0; 
4. n is the distribution modulus of fraction j and is greater than about 
0.001; 
5. D is the diameter of any particle in the consist and ranges from about 
0.05 to about 1180 microns; 
6. D.sub.s is the diameter of the particle in fraction j, measured at 1% 
CPFT on a plot of CPFT versus size D, is less than D.sub.L, and is greater 
than 0.05 microns; 
7. D.sub.L is the diameter of the size modulus in fraction j, measured by 
sieve size or its equivalent, and is from about 10 to about 1180 microns; 
and 
8. no more than about 0.05 volume percent of the particles in the slurry 
consist have a diameter less than about 0.05 microns; 
(f) the net zeta potential of said colloidal size particles of solid 
carbonaceous material is from about 15 to about 85 millivolts; and 
(g) the concentration of solid carbonaceous material in said slurry, the 
interstitial porosity of said consist, the specific surface area of said 
consist, and the zeta potential of said colloidal size particles of solid 
carbonaceous material are interrelated in accordance with the following 
formula: 
EQU V.sub.s +P.sub.s +SA+(240/ZP)=H 
wherein: 
1. V.sub.s is the percent, by volume, of solid carbonaceous material in 
said slurry; 
2. P is the porosity of said consist in the slurry, in percent; 
3. S.A. is the specific surface area of said consist in said slurry, in 
square meters per cubic centimeter; 
4. Z.P. is the net zeta potential of said colloidal size particles of 
carbonaceous material in said consist, in millivolts, and 
5. H is from about 75 to about 98. 
The slurry produced by the grinding process has a yield stress of from 
about 3 to about 18 Pascals. It is preferred that the yield stress be from 
about 5 to about 15 Pascals, and it is more preferred that the yield 
stress be from about 7 to about 12 Pascals. As is known to those skilled 
in the art, the yield stress is the stress which must be exceeded before 
flow starts. A shear stress versus shear rate diagram for a yield 
pseudoplastic or a Bingham plastic fluid usually shows a non-linear hump 
in the rheogram at the onset of flow; extrapolating the relatively linear 
portion of the curve back to the intercept of the shear stress axis gives 
the yield stress. See, for example, W. L. Wilkinson's "Non-Newtonian 
Fluids, Fluid Mechanics, Mixing and Heat Transfer" (Pergamon Press, New 
York 1960), pages 1-9, the disclosure of which is hereby incorporated 
herein by reference. Also see Richard W. Hanks, et al's "Slurry Pipeline 
Hydraulics and Design" (Pipeline Systems Incorporated, Orinda, Calif., 
1980), pages II- 1 to II-10, the disclosure of which is also hereby 
incorporated herein by reference. 
The Brookfield viscosity of the slurry is less than about 5,000 centipoise. 
The Brookfield viscosity is tested after the solids concentration of the 
slurry is adjusted to a solids content of 70 volume percent (the slurry is 
either diluted or concentrated until it has this concentration of solids) 
at ambient temperature, ambient pressure, and a shear rate of 100 
revolutions per minute. It is preferred that the viscosity of the slurry 
be less than 4,000 centipoise. It is more preferred that the viscosity of 
the slurry be less than 3,000 centipoise. In an even more preferred 
embodiment, the viscosity of the slurry is less than 2,000 centipoise. In 
the most preferred embodiment, the viscosity of the slurry is less than 
1,000 centipoise. 
The term "Brookfield viscosity", as used in this specification, describes 
viscosity as measured by conventional techniques by means of a Brookfield 
Synchro-Lectric Viscosimeter (manufactured by the Brookfield Engineering 
Laboratories, Stoughton, Mass., U.S.A.). 
The solids-liquid slurry produced contains a consist of finely divided 
particles of solid carbonaceous material dispersed in said liquid. Said 
consist has a specific surface area of from about 0.8 to about 4.0 square 
meters per cubic centimeter. It is preferred that said specific surface 
area be from about 0.8 to about 3.0 m.sup.2 /c.c. It is more preferred 
that the specific surface area be from about 0.8 to about 2.4 m.sup.2 /cc. 
In an even more preferred embodiment, the specific surface area is from 
about 0.8 to about 2.0 m.sup.2 /cc. 
As used in this specification, the term "specific surface area" refers to 
the summation of the surface area of equivalent spheres in the particle 
size distribution as measured by sieve analysis and sedimentation 
techniques; the particle size distribution of the consist in the slurry is 
first determined, it is assumed that all particles in the consist are 
spherical, and then one calculates the surface area based on this 
assumption. As used herein, the term "consist" refers to the particle size 
distribution of the solid phase of the solids-liquid slurry. 
For any given consist, one can determine the particle size distribution by 
means well known to those skilled in the art. For measuring particle sizes 
and for determining particle size distributions of pulverized and fine 
grind carbonaceous particles used for preparing a carbonaceous slurry, the 
following two means of measuring particle sizes can be used and are 
preferred: 
1. U.S. Series sieves Nos. 16, 20, 30, 40, 50, 70, 100, 140, 200, 270, are 
used to determine weights of carbonaceous particles passing through each 
sieve in the range of about (-) 1180 .mu.m to (-) 53 .mu.m. The cumulative 
volume percents of particles, dry basis, finer than (CPFT) a particular 
stated sieve size in microns is charted against the sizes in microns on a 
log-log chart, referred to herein as a "CPFT chart", to indicate the 
nature of the particle size distribution of 16 mesh.times.270 mesh 
particles. 
2. A Sedigraph 5500L (made by Micromeritics, Co., Norcross, Ga., U.S.) is 
used to measure particle sizes and numbers of particles in the 
carbonaceous material and in the slurry in the range of (-) 75 .mu.m to 
about 0.2 mm. The Sedigraph 5500L uses photo-extinction of settling 
particles dispersed in water according to Stoke's law as a means for 
making the above determinations. Other instruments, such as a Coulter 
Counter or combinations of the Leeds & Northrup Microtrac Particle 
Analyzers can also be used for similar accuracy. The results can be 
plotted on a CPFT chart. Although these data do not necessarily extend to 
the size axis at 1% CPFT, the "D.sub.s at 1%" can be determined by 
extrapolating the CPFT chart line to this axis and reading the intercept. 
This number, although not the true D.sub.s, can be effectively used in the 
computer algorithm to determine % porosity and specific surface area. 
In addition to the above methods, particle size measurements can be 
estimated from methylene blue index measurements to obtain an approximate 
determination of the wgt. % of colloidal particles of size below 1 mm. 
Such a procedure is described in A.S.T.M. Standard C837-76. This index can 
be compared with the surface area calculated by the CPFT algorithm. 
Once the particle size distribution of the consist is determined, it is 
assumed that each particle in the consist is spherical with a surface area 
of .pi.D.sup.2 ; the diameter D of the particles in each class of 
particles in the consist is known; and the surface area of the particles 
in each class is calculated and summed. 
The consist in the slurry has an interstitial porosity of less than about 
20 volume percent. It is preferred that said interstitial porosity be less 
than about 15 volume percent, and it is more preferred that said 
interstitial porosity be less than about 10 percent. The interstitial 
porosity is a function of the volume between the interstices of the 
particles in the slurry consist. For any given space full of particles, 
the interstitial porosity is equal to the "minimum theoretical porosity" 
in accordance with the equation presented below. 
EQU Minimum Theoretical Porosity=40% (1-[1/VA]) 
where VA is as defined by the following modified Westman-Hugill algorithm: 
##EQU2## 
wherein: A.sub.i =Apparent volume of a monodispersion of the i.sup.th size 
particle, 
X.sub.i =Mass fraction of the i.sup.th size particles, 
VA.sub.i =Apparent volume calculated with reference to the i.sup.th size 
particles, 
n=Number of particle sizes, and 
VA=Maximum value of VA.sub.i =Apparent volume of the mixture of n particle 
sizes. 
To determine the interstitial porosity of any consist, the particle size 
distribution of said consist can be determined by the method described 
above with reference to the measurement of the specific surface area. 
Thereafter, it is assumed that each particle in the consist is spherical, 
the volume of the particles is calculated in accordance with this 
assumption, and the interstitial porosity of the consist is then 
calculated in accordance with the above formula. It is noted that this 
calculated porosity is less than the true porosity of a consist as 
measured, for example, by liquid loss-due to the non-spherical morphology 
(shape) of the particles, and by invocation of D.sub.s at 1%. 
The slurry produced by the process of this invention contains a consist 
which is comprised of at least about 5 weight percent of colloidal 
particles, and, preferably, from about 5 to about 70 weight percent of 
colloidal particles. As used herein, the term "colloidal" refers to a 
substance of which at least one component is subdivided physically in such 
a way that one or more of its dimensions lies in the range of 100 
angstroms and 3 microns. As is known, these are not fixed limits and, 
occasionally, systems containing larger particles are classified as 
colloids. See Encyclopedia Of Chemistry, 2d Edition, Clark et al 
(Reinhold, 1966), page 203, the disclosure of which is hereby incorporated 
herein by reference. 
It is preferred that, in the carbonaceous consist used in the slurry, at 
least 5 weight percent of the carbonaceous particles are smaller than 
about 3.0 microns. It is preferred that from about 5 to about 70 weight 
percent of the carbonaceous particles in said consist be smaller than 3.0 
microns. In one preferred embodiment, from about 5 to about 30 weight 
percent of the carbonaceous particles in said consist are smaller than 3.0 
microns. In another preferred embodiment, from about 7 to about 20 weight 
percent of the particles in said consist are smaller than 3.0 microns. 
The slurry produced comprises a compact of finely-divided carbonaceous 
particles dispersed in fluid such as, e.g., finely-divided coal particles 
dispersed in water. The term compact, as used in this specification, 
refers to a mass of finely-divided particles which are closely packed in 
accordance with this invention. 
The particles in the compact of said slurry have a specified particle size 
distribution which is substantially in accordance with the aforementioned 
CPFT formula, wherein CPFT is the cumulative percent of the carbonaceous 
solid finer than a certain specified particle size D, in volume percent; k 
is the number of component distributions in the consist, is at least 1, 
and preferably is from about 1 to about 30, and most preferably is 1; 
X.sub.j is the fractional amount of the component j in the consist, is 
less than or equal to 1.0, and the sum of all X.sub.j 's in the consist is 
1.0; n is the distribution modulus of fraction j, is greater than about 
0.001, preferably is from about 0.001 to about 10.0 and more preferably 
from 0.01 to about 1.0, and most preferably is from about 0.01 to about 
0.5; D is the diameter of any particle in the consist and ranges from 
about 0.05 to about 1180 microns; D.sub.s is the diameter of the smallest 
particle in fraction j (as measured by extrapolating the CPFT chart line, 
if necessary, to one percent CPFT using data from sieve analyses plus the 
Micromeritics Sedigraph 5500L) and is generally greater than 0.05 microns 
but is less than D.sub.L, and no more than about 0.05 volume percent of 
the particles in the slurry consist have a size less than 0.05 microns; 
D.sub.L represents the diameter of the largest particle in fraction j 
(sieve size or its equivalent), it ranges from about 10 to about 1180 
microns, preferably is from about 30 to about 420 microns, and most 
preferably is from about 100 to about 300 microns; D.sub.L is the 
theoretical size modulus of the particle size distribution; when CPFT is 
plotted against size, the D.sub.L value is indicated as the intercept on 
the upper X axis of the CPFT/D plot. However, as is known to those skilled 
in the art, because of aberrations in grinding the coarse end of a 
particle size distribution, the actual top particle size is always larger 
than the D.sub.L obtained by, e.g., the particle size equation described 
in this case; thus, e.g., a D.sub.L size modulus of 250 microns will 
usually produce a particle distribution with at least about 98 percent of 
the particles smaller than 300 microns. Consequently, slurry has a compact 
with a particle size distribution which is substantially in accordance 
with the CPFT equation; minor deviations caused by the actual top size 
being greater than the D.sub.L are within the scope and spirit of this 
invention. 
When k is 1, the aforementioned equation simplifies to: 
##EQU3## 
when k is 2, the equation becomes: 
##EQU4## 
wherein: X.sub.1 +X.sub.2 =1.0 (i.e., the sum of the fractional parts is 
equal to the whole); when D is less than or equal to D.sub.s.sbsb.1, the 
first term in the parentheses (term I) is equal to 0.0; when D is greater 
than or equal to D.sub.L.sbsb.1, the first term in the parentheses (term 
I) is equal to 1.0; when D is less than D.sub.S.sbsb.2, the second term in 
the parentheses (term II) is equal to 0.0; when D is greater than 
D.sub.L.sbsb.2, the second term in the parentheses (term II) is equal to 
1.0. 
The reason for the aforementioned constraints of the terms in parentheses I 
and II is that each of these terms refers to the equation of one of the 
two components. 
In order to sum the fractional parts of the two component distributions, 
the above considerations must be included since particles of a certain 
size may be represented between the effective D.sub.S and D.sub.L of the 
total distribution but not between the D.sub.S or D.sub.L of one of the 
component distributions. Thus, the values in parentheses I and II are 
subject to the limitations that, when D is less than or equal to D.sub.s, 
the value for the term is 0.0 and when D is greater than D.sub.L.sbsb.j, 
the value of the term is 1.0. 
The equation given above for when k is 2 is simply the sum of two 
components where the fraction of component j.sub.1 is X.sub.1 and the 
fraction of component j.sub.2 is X.sub.2. Since, in this case, X.sub.1 and 
X.sub.2 make up the whole distribution, their sum must equal 1.0. 
In accordance with the above reasoning, when k=3, the equation becomes: 
##EQU5## 
When k=4, there is a fourth term in the equation equal to 
##EQU6## 
In the slurry produced, it is preferred that no more than 0.5 weight 
percent of the solid carbonaceous particles in the slurry have a particle 
size less than 0.05 microns. It is preferred that at least 85 weight 
percent of the carbonaceous particles in the slurry have a particle size 
less than 300 microns. It is more preferred that at least 90 weight 
percent of the carbonaceous particles in the slurry have a particle size 
less than 300 microns. In the most preferred embodiment, at least 95 
weight percent of the carbonaceous particles in the slurry have a particle 
size less than 300 microns. 
In a preferred embodiment, the fluid is water and the colloidal sized 
carbonaceous particles in the slurry have a net zeta potential of from 
about 15 to about 85 millivolts. The following discussion of zeta 
potential will refer to a coal-water slurry, it being understood that the 
discussion is equally applicable to, e.g., coke-water slurries, 
graphite-water slurries, etc. 
It is preferred that the colloidal sized particles of coal in the 
coal-water slurry have a net zeta potential of from about 15 to about 85 
millivolts. As used herein, the term "zeta potential" refers to the net 
potential, be it positive or negative in charge; thus, a zeta potential of 
from about 15.4 to 70.2 millivolts includes zeta potentials of from about 
-15.4 to about -70.2 millivolts as well as zeta potentials of from about 
+15.4 to about +70.2 millivolts. In a more preferred embodiment, said zeta 
potential is from about 30 to 70 millivolts. 
As used in this specification, the term "zeta potential" has the meaning 
given it in the field of colloid chemistry. Concise discussions and 
descriptions of the zeta potential and methods for its measurement are 
found in many sources including, T. M. Riddick, U.S. Pat. No. 3,454,487, 
issued July, 1969; Douglas et al., U.S. Pat. No. 3,976,582 issued Aug. 24, 
1976; Encyclopedia of Chemistry, 2nd edition, Clark et al., Reinhold Publ. 
Corp. 1966, pages 263-265; Chemical and Process Technology Encyclopedia, 
D. M. Considine, editor-in-chief, McGraw-Hill Book Company, N.Y., pages 
308-309; Chemical Technology: An Encyclopedic Treatment, supra, Vol. VII, 
pages 27-32; Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd 
Edition, Vol. 22, pages 90-97; and T. M. Riddick, Control of Colloid 
Stability Through Zeta Potential, Zeta-Meter, Inc. New York City. The 
disclosures of the aforementioned documents are hereby incorporated into 
this specification by reference. 
"Zeta potential" may be measured by conventional techniques and apparatus 
of electroosmosis such as those described, e.g., in Potter, "Electro 
Chemistry"; Cleaver-Hume Press, Ltd.; London (1961). Zeta potential can 
also be determined by measuring electrophoretic mobility (EPM) in any of 
several commercial apparatuses. In the present invention, a Pen Kem System 
3000 (made by Pen Kem Co. Inc. of Bedford Hills, N.Y.) was used for 
determining zeta potential in the examples herein. This instrument is 
capable of automatically taking samples of coal particles and producing an 
EPM distribution by Fast Fourier Transform Analysis from which the average 
zeta potential can be calculated in millivolts. 
The zeta potential is measured using very dilute samples of the &lt;10 .mu.m 
sized coal particles in the coal compact of the coal-water slurry. 
It is preferred that the zeta potential of the colloidal sized coal 
particles in the coal consist of the slurry be negative in charge and be 
from about -15.4 to about -70.2 millivolts. It is more preferred that said 
zeta potential be from about -30 to about -70 millivolts. 
In one embodiment, it is preferred that the zeta potential of said 
colloidally sized coal particles be "near maximum". "Near maximum zeta 
potential", as used in this specification, means a value of zeta 
potential, measured at constant electrical conductivity, below the maximum 
zeta potential as defined and discussed in the references cited in the 
portion of this specification wherein the term "zeta potential" is 
defined. It is sometimes necessary to normalize the zeta potential values 
with respect to the electrical conductivity of the carrier fluid because 
zeta potential is limited by the electrical conductivity of the carrier 
fluid. The near maximum zeta potential should be of a millivoltage 
sufficient to provide the coal particles with a repulsive charge great 
enough to disperse the coal particles in the coal-water slurry. In this 
embodiment, it is preferred that the zeta potential on the colloidal coal 
particles be from about 20 to about 95 percent of the maximum zeta 
potential. It is more preferred that the zeta potential on the colloidal 
coal particles be from about 40 to about 80 percent of the maximum zeta 
potential for this embodiment. 
The maximum zeta potential may be determined by measuring the Brookfield 
viscosity of the slurry at different zeta potentials. For a given system, 
maximum zeta potential has been reached when further increases in the 
surfactant concentration in the slurry do not further decrease the 
Brookfield viscosity of the system at 100 rpm. 
One preferred means for measuring the zeta potential is to grind a sample 
of coal in either a laboratory size porcelain ball mill with porcelain 
balls in distilled water at 30 weight percent solids for approximately 24 
hours or in a steel ball mill with steel balls at 30 weight percent solids 
for 16 hours or until all of the particles in the coal are less than 10 
microns in size. Small samples of this larger sample can then be prepared 
in a known way by placing them in a vessel equipped with a stirrer with a 
sample of water to be used as a carrier in the coal-water slurry. Various 
acidic and basic salts are then added in incremental amounts to vary the 
pH, and various concentrations of various candidate dispersing agent 
organic surfactants likewise are added in incremental amounts (e.g., grams 
per gram coal, both dry basis), alone or in combinations of two or more. 
These samples are then evaluated in any electrophoretic mobility, 
electroosmosis, or streaming potential apparatus to determine electrical 
data, from which the zeta potential is calculated in a known way. Plots of 
zeta potential, pH, and specific conductance vs concentration may then be 
made to indicate candidate surfactants, or combinations thereof to be used 
to produce the optimum dispersion of coal particles in the carrier water 
below the amount at which dilatency may be reached. 
Several typical means of producing the slurry are illustrated in FIG. 2. In 
a wet grinding method, carbonaceous material is charged to crusher 10 and 
crusher 12. In one embodiment, it is preferred that one carbonaceous 
material be charged to crusher 10 and another carbonaceous material be 
charged to crusher 12. In another preferred embodiment, different types of 
the same carbonaceous material are charged to crushers 10 and 12. In this 
latter embodiment, the carbonaceous material charged to crushers 10 and 12 
can be, e.g., coal, a coal fraction which contains less than about 30 
weight percent of volatilizable hydrocarbons (such as, e.g., anthracite or 
low volatile bituminous coal) can be charged to crusher 10, and a coal 
fraction which contains more than about 35 weight percent of volatilizable 
hydrocarbons (such as, e.g., lignite or high volatile bituminous coal) can 
be charged to crusher 12. 
Any of the crushers known to those skilled in the art to be useful for 
crushing carbonaceous material can be used as crusher 10 and/or crusher 
12. The same crusher can be used for crushers 10 or 12, or different 
crushers can be used. Thus, by way of illustration and not limitation, one 
can use, e.g., a rod mill, a gyratory crusher, a roll crusher, a jaw 
crusher, a cage mill, and the like. Generally, the carbonaceous material 
is crushed to a size of about 1/4".times.0, although coarser and finer 
fractions can be used. 
The crushed material from crusher 10 is fed through line 14. The crushed 
material from crusher 12 is fed through line 16. Part or all of the 
crushed material from crusher 10 can be mixed with part or all of the 
crushed material from crusher 10 by passing the crushed material in line 
14 and/or the crushed material in line 16 through transfer line 18. 
Alternatively, transfer line 18 can be closed, the crushed material from 
crusher 10 can be fed directly to mill 26, and the crushed material from 
crusher 12 can be fed directly to dry grinder 24. 
The crushed material from either crusher 10 or 12 can be sampled and 
measured for pH in the ph meter 13, which will be discussed later, thus 
establishing a baseline for the entire control circuit discussed later. 
The crushed material from crusher 10 can be fed through line 14 to mill 26. 
Mill 26 can either be a tumbling mill (such as a ball mill, pebble mill, 
rod mill, tube mill, or compartment mill), or a non-rotary ball or bead 
mill, such as stirred mills (including the Sweco dispersion mill, the 
Attritor, the Bureau of Mines mill described in U.S. Pat. No. 3,075,710), 
vibratory mills such as the Vibro-Energy mill, the Podmore-Boulton mill, 
the Vibratom, and the like. In general, the various processes and 
apparatuses which can be used to mill the crushed material are well known 
to those skilled in the art and are described in e.g., Perry and Chilton's 
Chemical Engineer's Handbook, Fifth Edition (McGraw Hill, New York, 1973) 
at pages 8-16 to 8-44 (crushing and grinding equipment), the disclosure of 
which is hereby incorporated by reference into this specification. 
In one preferred embodiment, mill 26 is a ball mill which, preferably, is 
run at a reduced speed. In this embodiment, the mixture is ground at said 
high solids content of from about 60 to about 82 volume percent of 
carbonaceous material and at a ball mill speed of from about 50 to about 
70 percent of the ball mill critical speed. Thus, for example, the 
grinding mixture can be ground in a ball mill at a speed of from about 50 
to about 70 percent of the ball mill critical speed. The critical speed of 
the ball mill is the theoretical speed at which the centrifugal force on a 
ball in contact with the mill shell at the height of its path equals the 
force on it due to gravity, and it is defined by the equation 
EQU N.sub.c =(76.6/D) 
wherein N.sub.c is the critical speed (in rpm), and D is the diameter of 
the mill (feet) for a ball diameter that is small with respect to the mill 
diameter. It is preferred to run ball mill 26 at less than about 60 
percent of its critical speed and, more preferably, at less than about 55 
percent of its critical speed. The use of reduced critical speed grinding 
produces a slurry with improved viscosity and stability properties. 
In general, mill 26 will have sufficient carbonaceous material and liquid 
fed to it so that it will contain from about 60 to about 82 volume percent 
of carbonaceous material. Crushed material is fed to mill 26 through line 
14. Alternatively or additionally, milled carbonaceous material (which 
might or might not contain carrier liquid, such as water) from mill 26 can 
be recycled through line 40 back into mill 26; this recycled milled 
carbonaceous material can be either fine milled material which passes 
through a sieve bend 38 and/or coarser milled material which does not pass 
through sieve bend 38. Alternatively or additionally, milled carbonaceous 
material from mill 46 (which preferably contains carrier liquid) can be 
recycled into mill 26 through lines 48, 58, and 60, or into mill 46 
through line 61. Alternatively or additionally, carbonaceous material 
(which preferably contains carrier liquid) which has been mixed in high 
shear mixer 64 can be recycled back into mill 26 through lines 66 and 60, 
or into mill 46 through lines 61. 
Carrier liquid is fed to mill 26 through line 20. A sufficient amount of 
said carrier liquid is fed into the mill 26 so that, in combination with 
all of the other feeds to mill 26, a solid-liquid mixture which contains 
from about 60 to about 82 volume percent of carbonaceous material is 
produced. 
The mill 26 will have sufficient solids and liquid fed to it so that it 
will contain from about 60 to about 82 volume percent of solid 
carbonaceous material. Generally, one should charge from about 0 to about 
10 volume percent more solid carbonaceous material to mill 26 than he 
desires in the final slurry product, subject to the qualification that in 
no event should more than 82 volume percent of such material be charged to 
the mill. 
Dispersing agent can be added to mill 26 through line 22. For a given 
material, dispersant, and solids content, a given amount of dispersant 
will optimize zeta potential; and this amount can be determined in 
accordance with the screening tests described in this specification. In 
general, a sufficient amount of dispersant is added through line 22 and/or 
line 62 and/or line 88 so that the slurry in mill 26 contains from about 
0.01 to about 4.0 weight percent of one or more dispersing agents, based 
on weight of dry carbonaceous material. 
A portion of the milled slurry from mill 26 is passed via line 28 through 
viscometer 30, density meter 32, ph meter 33, and line 27 back to line 28; 
a portion of the slurry passed to density meter 32 is also passed to 
particle size distribution analyzer 34. The function of viscometer 30, 
density meter 32, ph meter 33, and particle size distribution analyzer 34 
is to continually monitor the quality of the slurry being produced in mill 
26 so that, if necessary, the process can be adjusted the feeds of solids 
and/or solids-fluid slurry and/or liquid and/or dispersant and/or ground 
carbonaceous material and/or solid-liquid slurry to the mill. 
Any of the viscometers known to those skilled in the art can be used as 
viscometer 30. Thus, by way of illustration, one can use a Nametre 
Viscometer. The viscometer 30 indicates the viscosity of the ground 
slurry. If the viscosity of the ground slurry is higher than desired, then 
either mill 26 is not grinding the coal to produce a sufficiently high 
surface area and low porosity, and/or the amount or type of dispersing 
agent used is insufficient to produce a sufficiently high zeta potential 
on the colloidal carbonaceous particles; and the underflow slurry should 
be subjected to further tests (in density meter 32, ph meter 33, particle 
size distribution analyzer 34). 
Any of the density meters known to those skilled in the art can be used as 
density meter 32. Density meter 32 indicates the density of the slurry, 
which directly varies with its solids content. If the density of the 
slurry is lower or higher than desired, then it is possible that the 
particle size distribution of the carbonaceous compact in the underflow 
slurry is lower or higher than desired. In this case, the slurry should be 
subjected to further tests in particle size analyzer 34 to determine what 
the particle size distribution of the underflow slurry is and its 
attendant surface area and porosity are. 
Any ph meters known to those skilled in the art, such as, e.g., Leeds & 
Northrup in-line ph meter, can be used as ph meter 33. The ph meter 
measures the hydrogen ion concentration of the slurry, which can vary with 
water quality, the oxidation state of the carbonaceous or pyrite surfaces, 
soluble ingredients within the carbonaceous material, or errors in 
dispersant additions. 
Particle size distribution analyzer 34 analyzes the particle size 
distribution of the compact of the underflow slurry. Any of the particle 
size distribution analyzers known to those skilled in the art, such as, 
e.g., Micromeritics Sedigraph 5500L, Coulter Counter, Leeds and Northrup 
Microtrac Particle Analyzers, can be used as analyzer 34. From the data 
generated by analyzer 34, the specific surface area and the porosity of 
the compact of underflow slurry can be determined. 
Ground slurry from mill 26 is passed through line 28 to sieve bend 38. 
Sieve bend 38 may be 40 mesh sieve which, preferably, allows underflow 
slurry of sufficient fineness (such as, e.g., less than 420 microns) 
through to line 29 into mill 46 where it is subjected to further grinding; 
alternatively, all or part of this fine ground slurry can be recycled into 
mill 26 via line 40. Overflow particles which are greater than 420 microns 
are recycled via line 40 back into mill 26, where they are subjected to 
further grinding. 
The ground slurry from mill 26 which passes through sieve bend 38 can be 
passed through line 29 to mill 46. Mill 46 can be a rod mill, a ball mill, 
or a stirred ball mill; it preferably is a ball mill. It is preferred that 
the slurry be passed to mill 46 until at least about 95 volume percent of 
the particles in the slurry have particles less than about 20 microns, 
and, more preferably, less than about 15 microns; in the most preferred 
embodiment, the slurry in mill 46 is ground until at least 95 volume 
percent of the particles in the slurry have diameters less than about 5 
microns. Additional liquid and/or dispersant can be added to mill 46 via 
line 59 if necessary. 
A portion of the ground slurry from mill 46 is passed through a control 
circuit comprised of viscometer 50, density meter 52, and particle size 
distribution analyzer 54, pH meter 53, and line 56, wherein the slurry is 
analyzed as described above for the slurry passing from line 28 into 
viscometer 30, density meter 32, ph meter 33, and particle size 
distribution analyzer 34. The feed to mill 46 can be adjusted, as 
required, by feeding crushed carbonaceous material from a dry grinding 
mill 24 and/or by adjusting the feeds to mill 26. 
Slurry from density meter 52 is returned through line 56 to line 48. Part 
or all of ground slurry from mill 46 can be passed through lines 48, 58, 
and 60 back to mill 26, wherein it is fed as a recycle stream. 
Alternatively, or additionally, part or all of ground slurry from mill 46 
can be passed via line 61 to mill 46 as a recycle stream. Alternatively, 
or additionally, part or all of ground slurry from mill 46 can be passed 
into high shear mixer 64. Any of the high shear, high intensity mixers 
known to those skilled in the art can be used as high shear mixer 64 
and/or high shear mixer 86. Thus, by way of illustration and not 
limitation, one can use for the high shear mixer(s) a Banbury mixer, a 
Prodex-Henschel mixer, a Welex-Papenmeir mixer, and the like. These 
high-shear, intensive mixers are described on page 19-17 of Perry and 
Chilton's Chemical Engineer's Handbook, (McGraw Hill, New York, 1973), the 
disclosure of which is hereby incorporated by reference into this 
specification. 
Dispersing agent is passed through line 62 to high shear mixer 64 to 
optimize the zeta potential of the colloidal particles of the slurry in 
the mixer. A sufficient amount of dispersing agent is charged to this 
mixer so that the final coal slurry product contains from about 0.01 to 
about 4.0 weight percent of dispersant, based on the weight of dry coal. 
Some or all of the product from high shear mixer 64 can be recycled via 
lines 66 and 60 to ball mill 26, or via line 61 to mill 46. Alternatively 
or additionally, some or all of the product from high shear mixer 64 can 
be fed through line 68 to hopper 70 and thence to Moyno pump 74 for 
volumetric blending. 
The "Moyno pump", also referred to as a "progressive cavity" or "moving 
cavity" pump, is well known to those skilled in the art. It consists of a 
convoluted hardened steel rotor and an inverse convoluted elastomeric 
stator so designed that as the rotor turns it maintains full contact with 
the stator on one side and only point to point contact with the stator on 
the other side. This produces a sealed cavity which moves in the direction 
of discharge as the rotor turns. Using a variable speed drive this pump 
can deliver variable volume flow rates at reasonable pressures and at high 
viscosities. Using a pair of pumps as 74 and 75 allows accurate blending 
volumetrically of two converging streams of fluids. This is described on 
pages 19-14 to 19-23 of Perry & Chilton's Chemical Engineers Handbook, 5th 
edition, supra. 
The function of the Moyno pump in the process is to deliver the proper 
volumetric proportions of two streams from lines 68 and 42 or hoppers 70 
and 72 to line 73 to low shear blender 76 via line 73. The blend from 
blender 76 is then transferred via line 77 using Moyno pump 78 through 
line 80 to a cleaning apparatus 82. 
Material from Moyno pump 74 can be fed through line 73 to low shear blender 
76. Any of the low shear blenders known to those skilled in the art can be 
used. Thus, by way of illustration and not limitation, one can use a 
twin-blade conical mixer (Atlantic Research Corp.), a double-arm kneader 
mixer (Baker Perkins Inc.), a helical ribbon mixer, gate mixers, Poly-Eon 
continuous reactors (Baker Perkins), the Rietz Extructor, Ko-Kneader 
(Baker Perkins), Transfer mix (Sterling Extruder Corp.), Rotofeed (Baker 
Perkins), ZSK (Werner-Pfleiderer), Halo-flite Processor (Joy Mfg. Co.), 
Kneadermaster (Patterson Industries Inc.), etc. Thereafter, the product 
from low shear blender 76 can be fed through line 77 to Moyno pump 78 and 
thence through line 80 to cleaner 82. 
Cleaned slurry from cleaner 82 can be passed through line 83 to high shear 
mixer 86. Alternatively, or additionally, cleaner 82 can be bypassed in 
whole or in part and product from Moyno pump 78 and/or mill 24 can be 
passed through lines 17 and 84 to high shear mixer 86. Required amounts of 
dispersant and liquid are fed in lines 88 and 90, respectively to the high 
shear mixer. A final control circuit, comprised of viscometer 94, density 
meter 96, line 92, particle size distribution analyzer 98, zeta meter 100, 
ash and sulfur analyzer 102 and ph meter 103, allows one to analyze a 
portion of the slurry being produced in high shear mixer 86 so that 
appropriate adjustments can be made in the feeds. 
Any of the zeta meters known to those skilled in the art can be used as 
zeta meter 100. Similarly, any of the ash and sulfur analyzers known to 
those skilled in the art can be used as analyzer 102. 
FIG. 2 also illustrates a dry grinding process for making the slurry. In 
this process, which may be used separately and/or in conjunction with the 
wet grinding process, crushed solid carbonaceous material from crusher 12 
is passed through line 16 to dry grinder 24; part or all of the material 
from crusher 12 may alternatively be passed through transfer line 18 to be 
mixed with solid carbonaceous material from crusher 10 and thence passed 
through line 14 to mill 26. Any of the dry grinders known to those skilled 
in the art can be used as grinder 24. Thus, by way of illustration and not 
limitation, one can use a hammer mill. Thus, e.g., one can also use ball 
mills or the ring roller mills described on pages 8-33 and 8-34 of Perry 
and Chilton's Chemical Engineer's Handbook, 5th edition, supra. It is 
preferred to grind the crushed material in dry grinder 24 until it is 
pulverized, that is until it is a consist of about 40 mesh by 0. 
The pulverized solid carbonaceous material from dry grinder 24 can be 
passed through line 44 to mill 46 wherein it may be mixed with the feed 
from line 29 (or, alternatively, not mixed with any such additional feed) 
and thereafter processed as described hereinabove. Alternatively, or 
additionally, part or all of the pulverized material from dry grinder 24 
can be passed through line 15 and line 14 to mill 26. Alternatively or 
additionally, part or all of the pulverized carbonaceous material from dry 
grinder 24 can be passed through line 17 and fed directly into high shear 
mixer 86, where it is blended with liquid and dispersant and ground to 
make carbonaceous material-liquid slurry. 
In another embodiment, illustrated in FIG. 2, part or all of the underflow 
slurry which passes through sieve 38 can be passed through line 42 to 
hopper 72 and thence to Moyno pump 75. The product from Moyno pump 75 is 
then passed through line 73 to low shear blender 76 and processed as 
described above. 
The operation of the control circuit comprised of viscometer 94, density 
meter 96, particle size distribution analyzer 98, zeta meter 100, and ash 
and sulfur analyzer 102 will now be described, it being understood that 
the other control circuits in the process operate in a similar manner. 
In FIG. 2, control ciruits are shown which are comprised of a viscometer, a 
densitometer, a particle size analyzer, and a pH meter. As will be 
apparent to those skilled in the art, fewer or more such control circuits 
can be used in the process, and the control circuits can be located at 
points in the process other than those indicated in FIG. 2. 
A typical control circuit is comprised of viscometer 30, densitometer 32, 
particle size analyzer 34, and pH meter 33. This circuit continually 
monitors the viscosity, density, consist particle size distribution, and 
pH of the slurry, and it adjusts the process so that these factors are 
properly interrelated. 
If the density of the slurry is not within the target range, or if the 
viscosity is too low, then the control circuit determines this and adjusts 
the ratio of the solids flow rate in the process to the liquids flow rate 
in the process, thereby adjusting the solids/liquids ratio. 
If the viscosity of the slurry is higher than the target range, then the 
control circuit determines this and adjusts the dispersant concentration 
(insufficient dispersant can cause a viscosity increase), the solid and/or 
the liquid flow rate (an insufficient liquid flow rate will cause the 
solids/liquids ratio to be too high, and will thus cause the viscosity to 
increase), the pH (if the pH of the grinding mixture is too low, the 
viscosity might be too high), and/or the particle size distribution. The 
pH of the grinding mixture can be adjusted by adding more dispersant 
and/or a pH adjusting agent such as, e.g., caustic. It is to be understood 
that all of these factors are interrelated, and that the control circuit 
can, and preferably does, monitor and adjust all of these factors 
simultaneously. 
For any given solids-slurry system, the target particle size distribution 
can be determined by analyzing "ideal" slurry and determining its particle 
size distribution; an "ideal" slurry is one which has the required solids 
content and viscosity and which fits into the equations described 
elsewhere in this specification. The particle size distribution of this 
"ideal slurry" can be determined on two Leeds and Northrup Microtrac 
Particle Analyzers--the Extended Range Analyzer (300--3 .mu.m) and the 
Small Particle Analyzer (21--0.1 .mu.m). The percent of the particles in 
the slurry consist which are less than 300 microns, 212 microns, 150 
microns, 106 microns, 75 microns, 53 microns, 38 microns, 27 microns, etc. 
can be determined. Then, armed with this particle size profile for the 
ideal slurry, the particle size analyzer in the control circuit can 
continually analyze the particle size distribution of the slurry in the 
process and, if it is less than ideal, the control circuit can adjust the 
process accordingly. In general, the percent of the particles in the 
slurry consist which are less than a certain specified particle size can 
be adjusted by adjusting the relative feed rates of the solids and the 
liquids fed to the system. For example, if the particle size analyzer 
indicates that the percent of the particles in the consist less than 212 
microns is not within the target range, this can be adjusted by varying 
the dry carbonaceous material feed rate. For another example, a change in 
the entire particle size distribution of the slurry consist, including the 
percent less than 212 .mu.m, can be made by varying the solids/liquids 
ratio, i.e., by adjusting the volume percent solids in the grinding 
mixture. 
Of particular importance in the particle size distribution analysis is the 
control of the "n" and the specific surface area of the slurry consist. 
The "n" in the particle size distribution equation is proportional to the 
difference between the weight percent concentrations of two selected 
channels in the Microtrac FR analyzer; the difference between the weight 
percent concentrations of, e.g., particles less than 150 microns and 
particles less than 53 microns can be determined for the aforementioned 
"ideal" slurry; and, armed with this "ideal difference" between said 
concentrations, the particle size analyzer can continually determine this 
difference for the slurry in the process and, if it varies from the ideal, 
the control circuit can adjust the relative feed rates of the solids and 
liquids fed to the system. The specific surface area of the consist in the 
slurry is proportional to the difference between the weight percent 
concentrations of two selected channels in the Microtrac SPA analyzer; the 
difference between the weight percent of, e.g., particles less than 1.01 
and 0.34 microns can be determined for the aforementioned "ideal slurry"; 
and, armed with this "ideal difference", the particle size analyzer can 
continually determine this difference for the slurry in the process and, 
if it varies from the ideal, the control circuit can adjust the relative 
feed rates of the solids and liquids fed to the system. 
The control system described in FIG. 2 is capable, thus, of continually 
monitoring and adjusting the slurry solids content, the slurry viscosity, 
the particle size distribution of the slurry consist, the "n" of the 
slurry consist, and the specific surface area of the slurry consist. 
As indicated above, if the viscosity of the slurry is higher than the 
target rate, the control circuit determines this and can adjust the 
dispersant concentration and/or the solid flow rate and/or the liquid flow 
rate and/or the pH. Alternatively, or additionally, the control circuit 
can adjust the amount of reground carbonaceous fine material being 
recycled to the grinding mill; an insufficient amount of colloidally sized 
carbonaceous material in the slurry consist will cause the viscosity of 
the slurry to be too high, and the addition of finely ground carbonaceous 
material to such a slurry tends to reduce its viscosity. For example, if 
viscometer 30 determines that the slurry in mill 26 is too viscous, it can 
cause finely ground carbonaceous material from mill 46 and/or high shear 
mixer 64 to be recycled through line 60 to mill 26, thereby increasing the 
amount of fine material in the grinding mixture in mill 26 and tending to 
lower its viscosity. For example, if viscometer 94 determines that the 
slurry in high shear mixer 86 is too viscous, it can cause finely ground 
carbonaceous material from mill 46 and/or high shear mixer 64 to be 
recycled through line 60 to mill 26, thereby increasing the amount of fine 
material in the slurry ultimately fed to high shear mixer 86 through line 
84; it can recycle finely ground carbonaceous material from mill 46 
through lines 48, 58, 60, and 61 back into mill 46; it can recycle finely 
ground carbonaceous material from high shear mixer 64 through lines 66, 58 
and 48 back into high shear mixer 64; it can recycle finely ground 
carbonaceous material from mill 26 through lines 28 and 40 back into mill 
26; it can do any combination of the aforementioned steps; and the like. 
The aforementioned means of increasing the amount of finely ground 
carbonaceous material in mills 26 and 46 and mixers 64 and 86 are only 
illustrative, and those skilled in the art upon an examination of FIG. 2 
will appreciate other means which can be used. 
Thus, the control circuit can adjust the viscosity of the slurry in mill 26 
by adjusting the amount of carbonaceous material fed through line 14, the 
amount of carbonaceous material fed through lines 16 and 18, the amount of 
carbonaceous material fed through line 15, the amount of carrier liquid 
fed through line 20, the amount of dispersant fed through line 22, the 
amount of finely ground carbonaceous material recycled through lines 28 
and 40, the amount of finely ground carbonaceous material recycled through 
lines 48, 58, and 60, the amount of finely ground carbonaceous material 
recycled through lines 66 and 60, and/or the pH. Thus, the control circuit 
can adjust the viscosity of the slurry in mill through lines 66 and 60, 
and/or the pH. Thus, the control of the grinding mixture in mill 46 can be 
done by adjusting any or all of the aforementioned factors influencing the 
slurry viscosity in mill 26, (for the properties of the slurry coming out 
of mill 26 influence the properties of the slurry formed in mill 46), and, 
additionally or alternatively, the amount of carbonaceous material fed to 
mill 46 through line 44, and the amount of carbonaceous material fed to 
mill 46 through line 29. Thus, the control circuit can adjust the 
viscosity of the slurry in high shear mixer 64 by adjusting any or all of 
the aforementioned factors influencing the slurry viscosity in mills 26 
and 46 (for when the properties of these slurries are changed, they change 
the properties of the slurry in mixer 64) and, alternatively or 
additionally, the amount of dispersing agent added through line 62, and 
the amount of finely ground carbonaceous material recycled through lines 
66 and 58 to mixer 64. Thus, the control circuit can adjust the viscosity 
of the slurry in high shear mixer 86 by adjusting any of the 
aforementioned factors influencing the slurry viscosity in mill 26, mill 
46, and high shear mixer 64, and, alternatively or additionally, the 
amount of dispersing agent fed to mixer 86 through line 88, the amount of 
carrier liquid fed to mixer 86 through line 90, the amount of dry 
carbonaceous material fed to high shear mixer through line 17, the amount 
of finely ground carbonaceous material fed through line 42 to hopper 72, 
the pH of the slurry in mixer 86, and the like. 
Cleaner 82, referred to in FIG. 2, can be any of the carbonaceous-slurry 
cleaning apparatuses known to those skilled in the art. Thus, by way of 
illustration and not limitation, one can use the electrophoretic deashing 
cell illustrated on page 3 (FIG. 3) of Miller and Paker's Bureau of Mines 
Report of Investigations 7960 (United States Department of the Interior, 
Bureau of Mines, 1974), the disclosure of which is hereby incorporated by 
reference into this specification. Thus, one can clean said slurry by 
passing it onto a sedimentation device, such as a lamella filter, where it 
is allowed to settle. Thus, one can effect magnetic separation of the 
slurry and/or combine such magnetic separation with sedimentation in the 
form of a pre- or post-treatment step. 
In one preferred embodiment, cleaner 82 involves the cleaning process 
described in U.S. Pat. Nos. 4,186,887, and 4,173,530, the disclosures of 
which patents are hereby incorporated by reference into this application. 
In this preferred embodiment, it is preferred that no dispersing agent be 
added to the carbonaceous material-fluid mixture until after the mixture 
has passed through cleaner 82 into high shear mixer 86, at which time the 
required amount of dispersant is added; thus, in this preferred 
embodiment, no dispersing agent is added to mill 26. 
In one preferred embodiment, the carbonaceous solid material in the 
grinding mixture (and in the slurry produced therefrom) contains less than 
about 5 weight percent of ash. The term "ash", as used in this 
specification, includes non-carbonaceous impurities such as, e.g., 
inorganic sulfur, various metal sulfides, and other metal impurities as 
well as soil and clay particles. The fraction of ash in the carbonaceous 
material can be calculated by dividing the weight of all of the 
non-carbonaceous material in the slurry solids by the total weight of the 
slurry solids (which includes both carbonaceous and non-carbonaceous 
material). 
It is preferred that the slurry have a pH from about 5 to about 12 and, 
preferably, from about 7 to about 11. Conventional means may be used to 
adjust the pH of the slurry so that it is within these ranges. 
In one preferred embodiment, the slurry possesses a unique property; its 
viscosity decreases at a constant shear rate with time, at an increasing 
shear rate, and at an increasing temperature; this property greatly 
enhances the pumpability of the slurry. 
In one embodiment, the slurry is a yield-pseudoplastic fluid. The term 
"yield pseudoplastic fluid", as used in this specification, has the usual 
meaning associated with it in the field of fluid flow. Specifically, a 
yield pseudoplastic fluid is one which requires that a yield stress be 
exceeded before flow commences, and one whose apparent viscosity decreases 
with increasing rate of shear. In a shear stress vs. shear rate diagram, 
the curve for a yield pseudoplastic fluid shows a non-linearly increasing 
shear stress with a linearly increasing rate of shear. In a "pure" 
pseudoplastic system, no yield stress is observed so that the curve passes 
through the origin. However, most real systems do exhibit a yield stress, 
indicating some plasticity. For a yield pseudoplastic fluid, the viscosity 
decreases with increased shear rate. 
In an even more preferred embodiment, the slurry produced by the process is 
also thixotropic, i.e., its viscosity decreases with time at a constant 
shear rate. Furthermore, in this embodiment, the slurry has a negative 
temperature coefficient of viscosity, i.e., its viscosity decreases with 
increasing temperature. 
6. (c). Pumping the carbonaceous slurry in the laminar regime. 
The carbonaceous slurry provided for the process of this invention is 
unique, for it can be readily pumped at a high solids content (from about 
60 to about 82 volume percent) in the laminar regime. 
In the pumping process of this invention, the rate of flow of the 
carbonaceous slurry can generally be varied from 0 feet per second (at 
which point the slurry is not being pumped and is quiescent) up to the 
maximum design capacity of the pipeline system; the fact that the slurry 
is stable under both static and dynamic conditions allows one to vary the 
slurry flow rate and, consequently, the rate at which the slurry is 
delivered. This is particularly advantageous to the slurry user because it 
allows for variations in the consumption rate. 
In the pumping process of this invention, it is preferred that the slurry 
be pumped in the laminar flow regime. As used in this specification, the 
term "laminar flow" refers to flow in which the streamlines remain 
distinct from one another over the entire length; the streamlines need not 
be straight or the flow steady, as long as the above criterion is 
fulfilled. Laminar flow occurs when the Reynolds number in the system is 
less than about 2100. The Reynolds number is a dimensionless quantity 
which is proportional to the ratio of inertial force to viscous force in a 
flow system. 
The Reynolds number for any given system may be calculated by means well 
known to those skilled in the art. Thus, by way of illustration and not 
limitation, for a Newtonian fluid at a constant flow rate the following 
equation applies: 
##EQU7## 
N.sub.Re =the Reynolds number, and is from about 0 (at which point the 
slurry is quiescent) to about 2100; 
D=the internal diameter of the pipe the slurry is being pumped through, in 
feet, and generally ranges from about 0.083 feet (one inch) to about 4.0 
feet; 
V=the velocity at which the slurry is being pumped through the pipe, in 
feet per second, and generally ranges from about 0 (at which point the 
slurry is quiescent) to about 1200 feet per second; 
.rho.=the fluid density of the slurry, in pounds per cubic feet; and 
.mu.=the fluid viscosity of the slurry, in pounds per cubic feet-second, 
and is generally equal to cps/1488. 
A discussion of the Reynolds number is presented in, e.g., Moody, 
"Transactions of American Society of Mechanical Engineers", 66, 671(1944), 
the disclosure of which is hereby incorporated by reference into this 
specification. 
Table 1 indicates what the slurry velocity must be for a coal-water slurry 
whose coal has a specific gravity of 1.3 g/cc. solids content of either 60 
or 80 volume percent and at differing slurry viscosities in pipelines of 
differing diameters in order to achieve a Reynolds number of 2100 or less. 
As indicated by this table, e.g., for the 500 cps slurry, the slurry 
velocity must vary from 2.3 feet per second (for pumping the 80 volume 
percent slurry in the 4.0 foot pipeline) to 2.4 feet per second (for 
pumping the 60 volume percent slurry in the 4.0 foot pipeline). 
TABLE 1 
______________________________________ 
Velocity in feet per second of slurries 
in order to attain Re = 2100 
Solids concentration 
60 vol % solids 
80 vol % solids 
Pipe diameter 
4 in 1 ft 4 ft 4 in 1 ft 4 ft 
______________________________________ 
Slurry viscosity 
500 cps 28.8 9.58 2.4 27.4 9.12 2.3 
1000 cps 58 19.2 4.8 55 18.2 4.6 
5000 cps 288 96 24 274 91 23 
______________________________________ 
Laminar flow behavior corresponds to a Reynolds number below about 2100. 
Turbulent flow behavior corresponds to a Reynolds number greater than 
about 3,000. For carbonaceous slurries with solids contents greater than 
about 60 volume percent, it is improbable to achieve Reynolds numbers 
greater than 2,100 in very small pipes. However as pipe diameter increases 
and slurry viscosity decreases, the turbulent regime can eventually be 
reached. For example a 60 volume % slurry with a viscosity of 1000 cps can 
be pumped at up to 9.5 ft/sec in a 2 ft diameter pipe within the laminar 
regime. Thus, because the prior art taught that carbonaceous slurries must 
be pumped in a turbulent regime, the prior art also frequently taught that 
carbonaceous slurries with high solids content (such as, e.g., those 
containing greater than 60 volume percent of solids) were unpumpable. 
That the applicant's slurry can be pumped in the laminar flow regime is 
quite unexpected and advantageous. Laminar flow pumping is more 
economical. It involves a lower pipeline pressure drop, one may use 
thinner pipe, and there is less erosion of the pipe by the slurry being 
pumped through it. 
Any of the pumps known to those skilled in the art may be used in the 
process of this invention. It is preferred to use one or more pumps which 
do not degrade the chemistry or the particle size distribution of the 
slurry. Thus, in general, it is preferred to use one or more pumps which 
are oversized to minimize the number of strokes per unit and to reduce the 
velocity of the moving parts of the pump. In this embodiment, one should 
preferably choose a large, slow-moving pump to achieve a given flow rate 
rather than a small, fast-moving pump. 
Some of the pumps which can be used in the pumping process of this 
invention include positive displacement pumps. Positive displacement pumps 
(and those which approach positive displacement) will ideally produce 
whatever head is impressed upon them by the restrictions to flow on the 
discharge side. Actually, neglecting slippage, the maximum head attainable 
is determined by the power available in the drive and the strength of the 
pump parts. 
Reciprocating pumps can be used in the pumping process of this invention. 
Some suitable reciprocating pumps include, e.g., double-acting 
steam-driven reciprocating pumps, duplex double-acting steam-driven 
plunger pumps, the Aldrich-Groff variable-stroke power pump, the Milton 
Roy plunger-type metering pump, the Shriver-actuated diaphragm pump, the 
Dorr-Oliver pneumatically activated diaphragm pump, and the like. 
Descriptions of these pumps are contained on pages 6-11 through 6-13 of 
Robert H. Perry's and Cecil H. Chilton's "Chemical Engineer's Handbook, 
5th Edition (McGraw Hill, New York, 1973), the disclosure of which is 
hereby incorporated by reference into this specification. 
Screw pumps can be used in the pumping process of this invention and, in 
one embodiment, are preferred. Thus, by way of illustration, one can use a 
Warren-Quimby two-rotor screw pump; in this two-rotor version, the liquid 
is fed to either the center or ends, depending upon the direction of 
rotation, and progresses axially in the cavities formed by the meshing 
threads or teeth. One can use a three-rotor version of such a moving 
cavity pump, where the center rotor is the driving member while the other 
two rotors are driven. One can use a Moyno single-rotor screw pump in 
which a male metal rotor of unique design rotates without clearance in an 
elastomeric stationary female sleeve. These screw pumps are described on 
page 6-14 of said "Chemical Engineer's Handbook", supra, the disclosure of 
which is hereby incorporated by reference into this specification. 
The above description of pumps is merely illustrative, and those skilled in 
the art will recognize that other pumps which do not degrade the chemistry 
and/or the particle size distribution of the slurry can also be used; the 
use of these other pumps are within the scope of the claimed invention. 
FIG. 3 represents a schematic of a pump loop which can be used to test the 
pumping characteristics of the slurry used in the process of this 
invention. Pump loop 120 is comprised of pressure transducers 122 and 124, 
tubing 126, and Moyno pump 128. The pressure transducers 122 and 124 can 
be any of the pressure transducers known to those skilled in the art; they 
determine the pressure drop between them, if any, the slurry undergoes 
during pumping. Tubing 126 is preferably 1.0 inch tubing which is 21.0 
feet long between pressure gauges 122 and 124. Moyno pump 128 is a single 
rotor pump with a capacity of 7 gallons per minute. The test loop is 6.0 
feet wide, i.e., the distance 130 between the top and the bottom of tubing 
126 is 6.0 feet. 
FIG. 4 represents a schematic of another pump loop which can be used to 
test the pumping characteristics of the slurry used in the process of this 
invention. Pump loop 140 is comprised of Moyno pump 142, pinch valves 144 
and 146, Nameter viscometer 148, thermocouple 150, hose 152, pipe 154, 
flow meter 156, nipple 158, pipe 160, density meter 162, reducer 164, pipe 
166, union 168, hose 169, and sump 170, and mill discharge sump 171. Moyno 
pump 142 is preferably model #2E0E51-CDQ. Hose 152 is preferably 7'6" long 
between points 172 and 174, preferably has a 2.0 inch internal diameter, 
and preferably is made out of polyvinyl chloride plastic. Pipe 154 is 1.5" 
internal diameter pipe. Flow meter 156 preferably is a magnetic flow meter 
such as, e.g., a Brooks magnetic flow meter. Pipe 160 preferably has a 2.0 
internal diameter. Pipe 166 preferably has a 1.5" internal diameter. Union 
168 preferably is a 1.5" union. Hose 169 is preferably a 15.0 foot long 
hose with a 2.0" internal diameter which connects with mill discharge sump 
170. 
In one embodiment of the process of this invention, the slurry is 
periodically inverted (flipped over) while it is being pumped in the 
pipeline. This is accomplished by disposing a static mixer at specified 
points within the pipeline to invert the slurry every so often. In this 
embodiment, it is preferred to dispose from about 2 to about 10 static 
mixers between each of the pumping stations on the pipeline. The static 
mixer used can be any of the static mixers known to those skilled in the 
art and, preferably, is a single flight static mixer. 
One of the static mixers which can be used in the process of this invention 
is illustrated in FIG. 5. This mixer is sold under the trade name of 
"Static Mixer" by the Kenics Corporation, and it consists of one or more 
alternatehand helical elements juxtaposed at 90 degrees to one another 
inside a tubular housing. Fluid media passing through the mixer are forced 
to mix themselves through a progression of divisions and recombinations 
with 2.sup.n layerings per n elements. This "Static Mixer" is available in 
a variety of materials of construction and in sizes of from 1/8" diameter 
to several feet in inside diameter. In the embodiment shown in FIG. 5, 
mixer 190 is comprised of inlet 192 (not shown), housing 194, outlet 196, 
and mixing element(s) 198. Mixing elements 198 are shown in more detail in 
FIG. 6. The direction of flow of fluid through mixing element(s) 198 is 
shown in FIG. 6 by arrows 200, 202, and 204. 
The static mixer used in the process of this invention can be comprised of 
several mixing elements (or "flights"), or just one flight. It is 
preferred that the mixer be comprised of only a single flight. 
In another embodiment of the process of this invention, while the 
carbonaceous slurry is being pumped, additional dispersant is added to it. 
Elsewhere in this specification, applicant teaches how to determine what 
the optimum dispersant concentration may be for any given slurry. The 
carbonaceous slurry provided to the pump will have a given amount of 
dispersing agent in it. In this preferred embodiment, up to about 20 
weight percent (by weight of dispersing agent originally added) of 
additional dispersing agent can be added to carbonaceous slurry as it is 
being pumped. The dispersing agent can be added to the slurry by any means 
known to those skilled in the art. Thus, e.g., it can be injected directly 
into the pipeline as the slurry is traversing it. Thus, e.g., it can be 
added to the suction side of the pump. Thus, e.g., a portion of the 
additional dispersing agent can be added at the suction side of each of 
the pumps in the pipeline, provided that the total amount of dispersing 
agent added for all of the portions does not exceed about 20% of the 
dispersing agent originally present in the slurry. 
The following examples are presented to illustrate the claimed invention 
but are not to be deemed limitative thereof. Unless otherwise stated, all 
parts are by weight and all temperatures are in degrees centigrade. 
EXAMPLES 
EXAMPLE 1 
Preparation of Coal Samples for Measurements 
(a) Sieve analysis 
Although any standard procedure may be used to measure particle sizes of 
coal particles from a coal and then to calculate the particle size 
distribution, the procedure used in obtaining data discussed herein will 
be described. 
A weighed sample, e.g. 50 grams dry weight of coal is dispersed in 400 m.l. 
of carrier water containing 1.0 weight % Lomar D based on a weight of 
coal, dry basis, and the slurry is mixed for 10 minutes with a Hamilton 
Beach mixer. 
The sample is then remixed very briefly. It then is poured slowly on a 
stack of tared U.S. Standard sieves over a large vessel. The sample is 
carefully washed with running water through the top sieve with the rest of 
the stack intact until all sievable material on that sieve is washed 
through the sieve into the underlying sieves. The top sieve is then 
removed and each sieve in the stack, as it becomes the top sieve, is 
successively washed and removed until each sieve has been washed. The 
sieves are then dried in a dryer at 105.degree. C. and the residue on each 
is weighed in a known way. 
(b) Sedigraph analysis 
A separate sample finer than 140 mesh sieve size is carefully stirred, and 
a representative sample (about 200 m.l.) is taken for analysis. The rest 
may be discarded. 
About 2 eyedroppers of the dilute slurry are further diluted in 30 m.l. of 
distilled water with 4 drops of Lomar D added. This sample is stirred 
overnight with a magnetic stirrer. Measurement is then made with the 
Sedigraph 5500L. 
The Sedigraph 5500L uses photoextinction to measure particles. It 
essentially measures projected area of shadows, and the data must be 
converted to volume-%-finer-than. The data from the sieve and Sedigraph is 
combined to prepare a CPFT chart. D.sub.s at 1% is read from the CPFT 
line. 
EXAMPLE 2 
335 pounds of Upper Freeport coal with a Hardgrove grindability index (HGI) 
of about 88 and a specific gravity of 1.36 gm/c.m..sup.3, 94.5 pounds of 
water, 0.1 weight (153 grams) percent (by weight of coal) of sodium 
hydroxide and 0.7 weight percent (1060 grams) of "Lomar D" (the sodium 
salt of a condensed alkyl mononaphthalene sulfonic acid sold by the 
Diamond Shamrock Process Chemicals, Inc. of Morristown, N.J.) were charged 
to a Kennedy Van Saun 3 foot diameter.times.5 foot long ball mill 
(manufactured by the Kennedy Van Saun Co. of Danville, Pa.). The ball mill 
had 35 volume percent of a 2.0 inch top Bond ball charge comprised of 34 
weight percent of balls of 2.0 inch diameter, 43 weight percent of balls 
of 1.5 inch diameter, 17 weight percent of balls of 1.25 inch diameter, 
and 6 weight percent of balls of 1.0 inch diameter. 
The ball mill was run at a speed of 33 revolutions per minute, which 
corresponded to 70 percent of the critical speed of the mill. Grinding was 
conducted in the mill under these conditions until about 98.5 weight 
percent of the particles passed through a 50 mesh screen. The slurry so 
produced contained 78 weight percent of solids. 
The slurry produced in the ball mill was divided into three portions. The 
first portion, the slurry produced in the ball mill, had about 98.5 weight 
percent of its particles pass through a 50 mesh (300 micron) sieve; it was 
subjected to pumping tests as is. The second sample was passed through a 
70 mesh (210 micron) sieve; the material which passed through the sieve 
was subjected to pumping test. The third sample was passed through a 100 
mesh (150 micron) sieve; the material which passed through the sieve was 
subjected to pumping tests. 
The 50 mesh sample was then separated into three separate portions. The 
first portion was diluted until its solids content was 75 weight percent. 
The second portion was diluted until its solids content was 70 weight 
percent. The third portion was diluted until its solids content was 65 
weight percent. 
The 70 mesh sample was then separated into four separate portions. The 
first portion was diluted until its solids content was 75 weight percent. 
The second portion was diluted until its solids content was 71.5 weight 
percent. The third portion was diluted until its solids content was 70 
weight percent. The fourth portion was diluted until its solids content 
was 65 weight percent. 
The 150 mesh sample was separated into three separate portions which were 
diluted to solids contents of 71.5 weight percent, 70 weight percent, and 
65 weight percent, respectively. 
Calcium chloride flocculant was added to the various samples. To the 50 
mesh samples were added 14.14.times.10.sup.-4, 9.06.times.10.sup.-4, and 
4.99.times.10.sup.-4 grams of calcium chloride per gram of coal to the 65 
weight percent, 70 weight percent, and 75 weight percent samples, 
respectively. To the 70 mesh samples were added 2.52.times.10.sup.-4, 0, 
and 0 grams of calcium chloride per gram of coal to the 65, 70, and 75 
weight percent samples, respectively. To the 100 mesh samples were added 
12.62.times.10.sup.-4 and 5.44.times.10.sup.-4 grams of calcium chloride 
per gram of coal to the 65 weight percent and 70 weight percent samples, 
respectively. 
Each of the 50 mesh, 70 mesh, and 150 mesh samples was then subjected to 
pumping tests in the pump loop shown in FIG. 3. The pump loop was 
comprised of a single rotor Moyno Pump model number 2E OE51-CDQ, two 
pressure transducers (which were 21 feet apart), and 1 inch tubing 
connecting the two transducers (see FIG. 3). The Moyno pump was started up 
and initially run for 10 minutes; then the pump was shut down for 10 
minutes; then the pump was started up and run for three minutes; then the 
pump was shut down for quiescent time intervals of from 5 to 15 minutes to 
allow any thixotropic gel structure to rebuild. Then the pump was run 
continuously for 20 minutes. With one exception (the -300 micron, 75 
weight percent slurry), this last step was done after allowing the slurry 
to cool for about 16 hours; for the -300 micron, 75 weight percent slurry, 
the test was done immediately. After each slurry was subjected to the 
pumping test, the sample was analyzed to determine whether its particle 
size distribution had changed. 
Table 2 shows the results obtained with the 50 mesh (-300 micron) slurries. 
Table 3 shows the results obtained with the 70 mesh (-210 micron) 
slurries. Table 4 shows the results obtained with the 100 mesh (-150 
micron) slurries. 
TABLE 2 
______________________________________ 
Mesh size Slurry After Pumping 
(.mu.m) Initial at 75% at 70% 
at 65% 
______________________________________ 
-12 (1680) 100.00 100.00 100.00 
100.00 
-16 (1190) 100.00 100.00 99.96 100.00 
-20 (844) 99.99 99.99 99.88 100.00 
-30 (595) 99.97 99.98 99.84 99.94 
-40 (420) 99.90 99.96 99.81 99.96 
-50 (300) 99.46 99.70 99.60 99.76 
-70 (210) 97.37 98.36 98.43 98.64 
-100 (150) 90.90 93.82 94.37 94.73 
-140 (105) 82.96 86.33 87.21 87.76 
-200 (74) 72.84 76.67 77.37 78.00 
-270 (53) 65.89 70.61 71.36 71.66 
-325 (44) 62.26 66.39 67.45 68.01 
______________________________________ 
TABLE 3 
______________________________________ 
Mesh size 
Slurry After Pumping 
(.mu.m) Initial at 75% at 71.5% 
at 70% at 65% 
______________________________________ 
-12 (1680) 
100.00 100.00 100.00 100.00 100.00 
-16 (1190) 
100.00 100.00 100.00 100.00 100.00 
-20 (844) 
99.98 100.00 100.00 100.00 100.00 
-30 (595) 
99.96 100.00 100.00 100.00 100.00 
-40 (420) 
99.94 99.99 99.99 99.98 99.99 
-50 (300) 
99.82 99.92 99.95 99.91 99.93 
-70 (210) 
99.15 99.37 99.55 99.56 99.59 
-100 (150) 
96.00 96.54 96.92 97.24 97.16 
-140 (105) 
89.38 90.37 90.74 91.41 91.22 
-200 (74) 
80.43 81.43 82.01 82.94 82.67 
-270 (53) 
72.55 74.84 74.17 76.57 74.92 
-325 (44) 
70.24 72.02 71.97 73.00 72.41 
______________________________________ 
TABLE 4 
______________________________________ 
Mesh size Slurry After Pumping 
(.mu.m) Initial at 71.5% at 70% 
at 65% 
______________________________________ 
-12 (1680) 100.00 100.00 100.00 
100.00 
-16 (1190) 100.00 100.00 100.00 
100.00 
-20 (844) 100.00 100.00 100.00 
100.00 
-30 (595) 100.00 100.00 100.00 
100.00 
-40 (420) 100.00 100.00 100.00 
100.00 
-50 (300) 99.98 99.96 99.99 100.00 
-70 (210) 99.95 99.94 99.89 99.99 
-100 (150) 99.62 99.68 99.36 99.82 
-140 (105) 99.71 97.95 97.56 98.45 
-200 (74) 91.90 92.15 91.44 93.20 
-270 (53) 83.61 83.94 82.36 85.22 
-325 (44) 80.57 80.97 78.21 82.31 
______________________________________ 
As can be seen from these tables, there is a tendency to increase the fines 
content with no change in the top size of the consist. This indicates that 
comminution is not occurring, but rather that deagglomeration of fines is 
occurring. This improves the stability of the slurry, but may require 
additional dispersant to maintain low viscosity. Injection of additional 
dispersant as described above may be desirable. 
EXAMPLE 3 
In this Example, a sample of Island Creek Dorothy coal with a Hardgrove 
grindability index (HGI) of 46 was used. In substantial accordance with 
the procedure described in Example 2, it was wet ground in a Kennedy Van 
Saun 3'.times.5' ball mill until at least 99.2 weight percent of its 
particles were smaller than 50 mesh and 64.9 weight percent of its 
particles were smaller than 200 mesh. Sufficient water and coal were 
charged to the mill so that the ground slurry contained 75 weight percent 
of solids. The ground slurry was then diluted to a solids concentration of 
71.36 weight percent; this diluted slurry had a Brookfield viscosity, at 
100 r.p.m., of 1268 centipoise. 
The diluted slurry was then further diluted to 60% solids and then reground 
in a Union Process Attritor (model C-10, manufactured by the Union Process 
Company of Akron, Ohio). The Attritor stirrer was run at a speed of about 
312 r.p.m. using 1/4" steel balls. A paste-like reground product was 
obtained. 
Fifteen weight percent (15.0%) of the reground slurry and 85 weight percent 
(85.0%) of 4 mesh.times.0 Island Creek Dorothy coal were wet ground in 
said Kennedy Van Saun ball mill together with water. 
Five experiments were conducted. In the first of these, the slurry was 
ground until 99.07 weight percent of the particles were less than 50 mesh 
and 68.6 weight percent of the particles were less than 200 mesh; this 
slurry has a Brookfield viscosity at 100 r.p.m. of 1540 centipoise at 
73.01% solids. In the second of these, the slurry was ground until 99.01 
weight percent of the particles were less than 50 mesh and 66.88 weight 
percent of the particles were less than 200 mesh; this slurry had a 
Brookfield viscosity at 100 r.p.m. of 2048 centipoise at 73.61% solids. In 
the third of these, the slurry was ground until 98.12 percent of the 
particles were smaller than 50 mesh and 63.6 percent of the particles were 
smaller than 200 mesh; the slurry had a Brookfield viscosity of 2280 
centipoise at 73.58 percent solids. In the fourth of these, the slurry was 
ground until 98.75 weight percent of the particles were smaller than 50 
mesh and 65.56 weight percent of the particles were smaller than 200 mesh; 
this slurry had a Brookfield viscosity at 100 r.p.m. of 1340 centipoise at 
72.69 percent solids. In the fifth of these, the slurry had a Brookfield 
viscosity at a solids content of 71.28 weight percent and 100 r.p.m. of 
952 centipoise. The five slurries produced in these experiments were 
combined to produce a slurry which had a Brookfield viscosity at a solids 
content of 71.28 weight percent of 1632 centipoise. 
The slurry of this Example was tested in the pumping loop described in FIG. 
4. The results of these tests are described in Table 5. The starting 
slurry is described again as 0 hours pumped. Then the slurry was pumped 
for 4 hours at the designated conditions and then for 18 more hours at 
different pumping conditions. After the total 22 hours elapsed time, 0.5% 
Lomar D was added to the slurry which was pumped for an additional 12.3 
hours. During each of these runs, the pump speed was varied somewhat. In 
each case the average gallons per minute (gpm) and pump revolutions per 
minute (rpm) were measured. The slurry velocity was calculated for each 
speed. During these runs the maximum slurry throughput, pump speed, and 
slurry velocity were also recorded to obtain a sense of the worst 
conditions. The properties of the slurry after the pumping test are shown 
as the Brookfield viscosity at 100 r.p.m. and the % less than 200 mesh for 
the size consist. This shows that there is an increase in viscosity due to 
the increase in surface area associated with either comminution or 
deagglomeration which requires additional dispersant. The last column 
shows the number of times the slurry passes through the pump. This, of 
course, shows the extreme severity of the test. No practical delivery 
system would ever be designed to pass the same material repeatedly through 
the same pump so many times. A variable speed drive connected to the pump 
would allow throttling due to the stability of this slurry in the laminar 
regime so that a throttling recirculating bypass loop would not be 
desired. 
TABLE 5 
__________________________________________________________________________ 
Average Final Properties 
pump Maximum 
visc. @ Number 
Hours 
% vel 
pump 100 % &lt; 200 
pump 
pumped 
Solids 
gpm 
rpm 
fps 
gpm 
rpm 
hrs 
rpm mesh cycles 
__________________________________________________________________________ 
0 71.6 870 
65.8 -- 
4 71.6 
14.8 
125 
2.7 
14.8 
125 
4 1000 
66.9 460 
22 71.6 
25 215 
4.6 
50 425 
0.4 
4450 
70.3 3820 
34.3 72.1 
37 313 
6.8 
50 425 
0.3 
5600 
72.4 7535 
__________________________________________________________________________ 
EXAMPLE 4 
The procedure of Example 3 was substantially repeated, with the exception 
that a Pittsburgh coal with a Hardgrove grindability index (HGI) of about 
66 was used. The coal was wet ground until 98.94 weight percent of its 
particles were smaller than 50 mesh. A slurry containing 75 weight percent 
solids was obtained, and it was diluted to 70 weight percent solids; the 
Brookfield viscosity of the diluted slurry at 100 r.p.m. was 840 
centipoise. 
The diluted slurry was further diluted to 60 weight percent and then 
reground in the Union Process Attritor in accordance with the procedure of 
Example 2. Fifteen weight percent of the reground slurry and 85 weight 
percent of 4.times.0 United Eastern Pittsburgh coal were wet ground in the 
Kennedy Van Saun ball mill in five separate experiments, which are 
summarized below in Table 6. 
TABLE 6 
______________________________________ 
viscosity 
@ 100 % &lt; 50 % &lt; 200 
% Solids r.p.m. mesh mesh 
______________________________________ 
72.70 2640 98.93 70.68 
72.49 1900 98.86 70.16 
72.45 2540 98.99 71.05 
72.53 1324 98.43 70.04 
72.00 1940 NA NA 
Avg 72.43 2069 
______________________________________ 
The five samples were combined to produce a sample which had a Brookfield 
viscosity at 100 r.p.m. and 72.43 weight percent solids of 2069 
centipoise. In accordance with the procedure of Example 2, this slurry was 
tested in the pumping test loop described in Example 3. Table 7 summarizes 
the results obtained. 
TABLE 7 
__________________________________________________________________________ 
Final 
Average Properties 
pump Maximum visc. @ Number 
Hours 
% vel 
pump 100 % &lt; 200 
pump 
pumped 
Solids 
gpm 
rpm 
fps 
gpm 
rpm 
hrs 
rpm mesh cycles 
__________________________________________________________________________ 
0 70.9 
-- -- -- -- -- -- 1225 
70.0 -- 
5 71.0 
23.5 
203 
4.4 
30 262 
2.67 
5800 
74.5 768 
7.5 70.2 
30 262 
5.7 
40 346 
0.75 
1592 
NA 1377 
__________________________________________________________________________ 
EXAMPLE 5 
16.3 pounds of Pittston Moss number 1 coal with a Hardgrove grindability 
index (HGI) of about 58, 4.5 pounds of water, 51.8 grams Lomar D (0.7 
weight percent), and 3.7 grams (0.05 weight percent) of sodium hydroxide 
were charged to an Abbe ball mill with lifters to form a grinding mixture 
comprising 78 weight percent of coal. The ball mill used was a 16" Abbe 
ball mill (model Double No. 2, manufactured by the Paul O. Abbe Company of 
Little Falls, N.J.); it had 35 percent volume of 2.0 inch top Bond ball 
mill size and was run at a speed of 34 revolutions per minute, which 
corresponded to 51 percent of the ball mill critical speed. The grinding 
mixture was ground until at least about 98.8 weight percent of the coal 
particles in the slurry were smaller than 50 mesh. The slurry was diluted 
to a solids concentration of 73 weight percent, and its Brookfield 
viscosity was measured at this concentration under ambient temperature and 
pressure conditions; the viscosity of the slurry was 900 centipoise. 
In accordance with the procedure described in Example 1, the particle size 
distribution of the 73 weight percent slurry was determined. The ball 
charge was removed from the aforementioned Abbe 16" ball mill, and 2.5 
gallons of the 73 weight percent slurry were charged into the Abbe 16" 
ball mill. Each ball mill lifter was approximately 1/2" deep.times.1/2" 
wide and extended the 12" length of the ball mill, and there were four 
such lifters welded into the ball mill. The purpose of the lifters was to 
simulate severe conditions during pumping. No balls were added to the mill 
since the purpose of this experiment was to provide a severe test of the 
treatment a slurry would receive travelling through a pipe which may have 
a rough interior surface. The Abbe ball mill with the lifters was run for 
210 hours with the 2.5 gallons of the slurry in it at 50 revolutions per 
minute. Then the slurry was removed from the ball mill, its viscosity was 
tested, and its particle size distribution was analyzed in accordance with 
the procedure described in Example 1. 
The viscosity of the slurry after the simulated pumping test was 2000 
centipoise. The particle size distribution of the slurry before and after 
the simulated pumping test is shown in Table 8. 
TABLE 8 
______________________________________ 
Weight percent of the 
coal particles smaller 
Particle size, than the stated mesh size 
in microns Before test 
After test 
______________________________________ 
0.24 0.07 0.16 
0.34 0.48 0.72 
0.43 1.96 2.45 
0.66 3.81 4.46 
1.01 5.89 6.63 
1.69 8.45 9.29 
2.63 11.00 11.91 
3.73 13.90 14.92 
5.27 17.49 18.83 
7.46 21.38 22.89 
10.55 26.65 28.32 
14.92 32.32 34.72 
21.10 37.06 40.23 
23.57 39.02 42.21 
28.43 42.51 45.71 
34.28 46.26 49.45 
41.34 50.30 53.43 
44.00 51.71 54.82 
49.84 54.64 57.69 
53.00 56.14 59.15 
60.10 59.31 62.23 
72.47 64.33 67.08 
74.00 64.92 67.64 
105.00 75.55 76.03 
149.00 85.21 86.24 
297.00 98.71 98.85 
595.00 99.99 99.99 
841.00 100.00 100.00 
______________________________________ 
EXAMPLE 6 
The procedure of Example 5 was substantially followed, with two exceptions. 
Petroleum coke was used instead of Pittston Moss #1 coal to prepare the 
slurry for the test, and the slurry initially produced in the Abbe ball 
mill (before the simulated pumping test) contained 80 weight percent of 
coke. This slurry was then diluted to a concentration of 76 weight percent 
and a viscosity of 900 centipoise before it was subjected to the simulated 
pumping test. The viscosity of the 76 weight percent slurry after the 
simulated pumping test was 700 centipoise. Table 9 shows the particle size 
distribution of the coke slurry before and after the simulated pumping 
test. 
TABLE 9 
______________________________________ 
Weight percent of the 
coke particles smaller 
Particle size, than the stated mesh size 
in microns Before test 
After test 
______________________________________ 
0.24 0.08 0.13 
0.34 0.74 0.87 
0.43 2.99 3.05 
0.66 5.76 5.67 
1.01 8.79 8.51 
1.69 12.45 12.05 
2.63 15.97 15.54 
3.73 19.84 19.34 
5.27 24.24 23.70 
7.46 28.72 28.20 
10.55 34.40 34.31 
14.92 39.90 39.90 
21.10 43.99 43.66 
23.57 45.97 45.64 
28.43 49.46 49.14 
34.28 53.15 52.85 
41.34 57.06 56.78 
44.00 58.41 58.13 
49.84 61.19 60.93 
53.00 62.59 62.35 
60.10 65.56 65.33 
72.47 70.18 69.99 
74.00 70.71 70.53 
105.00 78.48 78.38 
149.00 87.23 87.34 
297.00 98.98 98.92 
595.00 99.98 99.99 
841.00 99.98 99.99 
1190.00 99.99 99.99 
1680.00 100.00 100.00 
______________________________________ 
It is to be understood that the foregoing description and Examples are 
illustrative only and that changes can be made in the ingredients and 
their proportions and in the sequence and combinations of process steps as 
well as other aspects of the invention discussed without departing from 
the scope of the invention as defined in the following claims.