Method and apparatus for moving coal including one or more intermediate periods of storage

Finely divided coal is slurried with liquid carbon dioxide and pumped from a source (mine, dump, railway car, etc.) to a loading pier where, after deslurrying, the coal is pneumatically carried by gaseous carbon dioxide into a storage facility or directly to a waterborne carrier. The coal is maintained under a blanket of carbon dioxide gas during storage and transport. When the waterborne carrier, which may be an ocean going vessel or an inland waterway vessel, reaches its destination, the coal is removed using carbon dioxide gas and then delivered to storage or a use point. If the use point is some distance away, the coal may be reslurried with liquid carbon dioxide and pumped to its final destination.

This invention relates to method and apparatus for moving coal, including 
one or more intermediate periods of storage, e.g., by waterborne carrier; 
and more particularly to moving coal, including the use of a waterborne 
carrier, using carbon dioxide, in gaseous and liquid form as a 
transporting agent. 
The ever-increasing emphasis on the use of so-called "steam coal" as a 
replacement for oil as a boiler fuel and as an energy source for many 
other applications points up the need for improved method and apparatus 
for transporting the coal, both within the United States and from the 
United States to foreign countries. At present the transporting of coal by 
waterborne carriers, e.g., ocean-going colliers or internal waterway 
barges, requires the delivery of the coal to a port by rail and the 
subsequent loading of the coal at the port onto the waterborne carrier by 
mechanical loading means. To provide the necessary coal transport point at 
a coal-loading pier requires additional railroad lines and switching 
facilities, and specialized dumping equipment, conveyors and port-loading 
equipment, as well as the auxiliary facilities necessary to maintain all 
of this equipment in operation. Similar equipment is, of course, required 
at a coal receiving port. Moreover, many ports which could otherwise be 
used to ship or receive coal are not usable for the purpose because the 
channels leading into them are not deep enough to handle the larger 
coal-carrying vessels. The costs involved in constructing new coal-loading 
piers or enlarging the present ones, as well as of deepening channels 
where necessary, are extremely high, and the operation of such facilities 
once installed is labor intensive. Finally, the construction and use of 
such facilities present environmental problems, both with regard to the 
handling of the coal and the dredging of channels. 
It would therefore be desirable to have improved method and apparatus for 
transporting coal, including the use of a waterborne carrier, which 
minimize the requirements for new pier construction and channel 
modifications and which thus offer within a relatively brief period of 
time the possibility of materially increasing the capacity to ship coal 
both within the United States and intercontinentally. 
It is therefore a primary object of this invention to provide an improved 
method for moving coal which includes the use of a waterborne carrier. It 
is another object to provide a method of the character described which 
minimizes the amount of construction required at a coal-loading pier by 
eliminating the need for dumping equipment, for mechanical conveyors 
capable of handling coal in lump form, and for additional railroad 
facilities. It is an additional object to provide a method for moving coal 
which is particularly suited to automated operation, is flexible in its 
adaptability to a wide range of situations and is capable of handling all 
types of coals. A further object of this invention is to provide a method 
for moving coal which offers the possibility of minimizing or even 
eliminating serious environment problems associated with both the handling 
of the coal itself and with the need to provide deeper harbor channels. 
Another primary object of this invention is to provide improved apparatus 
for moving coal which includes the loading and/or unloading of coal on a 
waterborne carrier such as an ocean-going collier or an internal waterway 
barge. It is still a further object to provide apparatus of the character 
described which eliminates the need for dumping equipment, mechanical 
conveyors, mechanical port loading and unloading equipment and extensive 
additional rail facilities along with the auxiliary facilities required to 
operate such equipment. An additional object is the providing of such 
apparatus which is particularly suited for operation as an essentially 
completely automated, closed and pollution-free system. 
Other objects of the invention will in part be obvious and will in part be 
apparent hereinafter. 
The invention accordingly comprises the several steps and relation of one 
or more of such steps with respect to each of the others, and the 
apparatus embodying features of construction, combinations of elements and 
arrangement of parts which are adapted to effect such steps, all as 
exemplified in the following detailed disclosure, and the scope of the 
invention will be indicated in the claims. 
According to one aspect of this invention there is provided a method of 
transporting coal, including one or more intermediate periods of storage, 
comprising the steps of providing coal in finely divided particulate form; 
storing the finely divided coal in a storage space under a protective 
blanket of gaseous carbon dioxide; introducing the coal into or 
withdrawing the coal from the storage space by pneumatically pumping it 
with gaseous carbon dioxide; and pumping the coal as a coal/liquid carbon 
dioxide slurry to or from the vicinity of the storage space before 
introducing the coal into or after withdrawing the coal from the storage 
space. 
According to another aspect of this invention there is provided a method of 
loading coal onto a waterborne carrier, comprising the steps of providing 
coal in finely divided particulate form in a coal/liquid carbon dioxide 
slurry; removing the coal from the slurry; pneumatically pumping the coal 
onto a waterborne carrier; and maintaining a protective gaseous blanket 
over the coal in the carrier. 
According to a further aspect of this invention there is provided a method 
of unloading coal from a waterborne carrier characterized by the step of 
pneumatically pumping coal with gaseous carbon dioxide or air from a 
waterborne carrier to a predetermined point. 
Yet another aspect of this invention is the providing of a system for the 
transportation of coal including one or more intermediate periods of 
storage, comprising, in combination, storage means to store coal in finely 
divided particulate form under a protective blanket of gaseous carbon 
dioxide; pneumatic pumping means arranged to convey the coal into or 
withdraw the coal from the storage means by penumatically pumping it with 
gaseous carbon dioxide; slurrying means arranged to form a pumpable 
coal/liquid carbon dioxide slurry; deslurrying means arranged to separate 
the coal from the slurry; and slurry pumping means arranged to pump the 
slurry from said slurrying means to deslurrying means, the order of means 
in the system being the slurrying means, the slurry pumping means, the 
deslurrying means and the pneumatic pumping means to convey the coal into 
the storage means, and the pneumatic pumping means, the slurrying means, 
the slurry pumping means and the deslurrying means to withdraw the coal 
from the storage means. 
According to a still further aspect of this invention there is provided 
apparatus for loading coal onto a waterborne carrier, comprising, in 
combination, coal supply means to provide coal in finely divided 
particulate form; slurrying means arranged to form a pumpable liquid 
carbon dioxide slurry with the coal; deslurrying means arranged to 
separate the coal from the slurry and located in the vicinity of an 
anchorage for the carrier; slurry pumping means arranged to pump the 
slurry from the slurrying means to the deslurrying means under conditions 
of temperature and pressure to maintain the carbon dioxide in liquid form; 
and pneumatic pumping means arranged to convey the coal dispersed in 
gaseous carbon dioxide from the deslurrying means onto the waterborne 
carrier. 
According to a final aspect of this invention there is provided apparatus 
for unloading coal from a waterborne carrier characterized as comprising 
pneumatic pumping means arranged to discharge coal in finely divided 
particulate form dispersed in gaseous carbon dioxide or air from a 
waterborne carrier through conduit means to a predetermined point.

In the method of this invention, liquid and gaseous carbon dioxide are used 
as carriers for the coal in the form of finely divided particulate 
material. The coal forms a pumpable slurry with the liquid carbon dioxide 
and can be pneumatically conveyed in gaseous carbon dioxide. In order to 
be handled in this manner the coal particules must be sized to pass a U.S. 
50-mesh screen, i.e., the particles should be not greater than about 300 
microns in diameter. A minor percentage (e.g., up to about 40% by weight) 
of the coal may be sized fine enough to pass a 325-mesh screen (40 microns 
in diameter). It is, however, preferable to use coal having a controlled 
particle size distribution, this distribution being optimized for the 
viscosity of the liquid carbon dioxide being used as detailed below. The 
size distribution of the coal particles should preferably be that which 
give rise to a stable slurry, i.e., a slurry from which the coal particles 
will not settle out to any appreciable degree. This allows a pipeline 
containing slurry to be shut down and have the flow therethrough restarted 
by only restarting the pump. 
The use of liquid carbon dioxide to form a pumpable slurry has distinct 
advantages over a coal/water slurry, including the elimination of the need 
to deplete critical water supplies in a number of coal-producing Western 
states and the difficulties inherent in separating the coal from the water 
slurry at the point of storage and/or use. Moreover, it allows the making 
of slurries with those types of coals having high concentrations of 
water-reactive alkaline constituents. 
In U.S. Pat. No. 4,206,610 I have disclosed a novel method for transporting 
coal which comprises suspending coal in finely divided form in liquid 
carbon dioxide to form a coal/liquid carbon dioxide slurry and pumping the 
slurry from a coal source point to a coal use point through a pipeline 
under conditions of temperature and pressure to maintain essentially all 
of the carbon dioxide in liquid form. According to a preferred embodiment 
of this method, the carbon dioxide is maintained at a temperature between 
about -20.degree. C. and 30.degree. C. and at a pressure between about 20 
and about 150 atmospheres. This patent also discloses a novel apparatus 
for transporting coal in finely divided form from a coal source point to a 
coal use point which comprises, in combination, slurry forming means at a 
coal source point to form a coal/liquid carbon dioxide slurry; deslurrying 
means at a coal use point to deslurry the coal/liquid carbon dioxide 
slurry to provide coal for combustion and essentially coal-free carbon 
dioxide; and slurry pipeline means connecting the slurry forming means and 
the deslurrying means arranged to carry the coal/liquid carbon dioxide 
slurry under conditions of temperature and pressure to maintain 
essentially all of the carbon dioxide in liquid form. 
I have now found that the use of a coal/liquid carbon dioxide slurry in 
conjunction with gaseous carbon dioxide makes it possible to handle, store 
and move coal, including transportation on a waterborne carrier, without 
the need for the presently used equipment now used at coal loading and 
unloading piers. Moreover, it is possible to load a coal-carrying vessel 
anchored at a point remote from the pier or dock itself, thus eliminating 
the need for deepening harbor channels, for the vessel may remain out of 
the harbor in deep water in a manner similar to the present practice of 
unloading oil tankers. 
FIGS. 1A and 1B diagram the method and apparatus making up the coal 
handling system of this invention used in loading onto a waterborne 
carrier. The alternative embodiments available will become apparent from 
the following detailed description of FIGS. 1A and 1B. 
The coal to be handled may originate at any suitable source point 8, e.g., 
at the coal mine itself, at a coal dump removed from the mine or directly 
from some form of conventional coal moving equipment such as a railroad 
car. The coal is prepared for slurrying at a preparation point 9 by 
reducing it to the desired particle size distribution, e.g., by grinding 
or other well-known technique and, if necessary, classifying with respect 
to particle size. Such preparation and handling follow standard procedures 
and may be carried out in conventional, commercially available equipment. 
The coal in finely divided particulate form is then slurried at 10 with 
liquid carbon dioxide supplied from a suitable source 11, e.g., a 
pressurized storage vessel. The carbon dioxide may, if desired, be 
obtained by burning coal and recovering it in essentially pure form from 
the combustion gases; or it may be recycled from a slurry delivery point; 
or any suitable combination of such sources may be used. 
Although the pressure of the liquid carbon dioxide in the slurry as it is 
pumped through the coal/liquid carbon dioxide pipeline 12 will range 
between about 20 and about 150 atmospheres and the temperature will range 
between about -20.degree. C. and 30.degree. C., liquefaction and storage 
of the carbon dioxide need not be carried out within this range since 
adjustments in pressure and temperature may be made as the liquid carbon 
dioxide is conducted from storage to the slurrying equipment. 
FIGS. 2 and 3 illustrate two embodiments of method and apparatus suitable 
for forming the coal/liquid carbon dioxide slurry. One embodiment, based 
on slurrying successive batches of coal, is illustrated in FIG. 2. As will 
be seen in FIG. 2, there are provided a number of pressurizable coal bins 
100, 101, and 102 which are connected to a coal storage bin 103 through a 
coal conduit 104 having a valve 105 and communicating with a main conduit 
106. Branch conduits 107, 108, and 109, having valves 110, 111 and 112, 
respectively, lead from main conduit 106 to the pressurizable coal bins. A 
liquid carbon dioxide storage vessel 113 provides both gaseous carbon 
dioxide, through line 114 and valve 115, and liquid carbon dioxide, 
through line 116, pump 117 and valve 118, to the pressurizable coal bins, 
by way of branch conduits 119, 120 and 121 having valves 122, 123 and 124, 
respectively. Each of the coal bins is equipped with a suitable stirring 
means 125, 126 and 127 and each has a slurry discharge line, 128, 129 and 
130, controlled by valves 131, 132 and 133, respectively, and 
communicating with main slurry pipeline 12. 
The operation of the apparatus of FIG. 2 in forming the required 
coal/liquid carbon dioxide may be illustrated in the following example in 
which it is assumed that pressurizable coal bin 100 is to be used. To 
begin, all valves except 105 and 110 are closed and coal is pumped or fed 
by gravity into bin 100 to a predetermined level. Valve 105 is then closed 
and valve 115 is opened to allow high-pressure gaseous carbon dioxide to 
flow into bin 100 and pressurize it to the desired level. Subsequently, 
valve 115 is closed and valve 122 is opened to permit liquid carbon 
dioxide to be pumped into bin 100 and to be slurried, by stirring, with 
the pressurized coal. After a sufficient quantity of liquid carbon dioxide 
has been pumped into bin 100, valves 122 and 110 are closed and valve 131 
is opened to discharge the coal/liquid carbon dioxide slurry into main 
slurry pipeline 12 for transport through the pipeline. By using each 
pressurizable coal bin in turn in the manner described, it is possible to 
provide an essentially continuous supply of slurried coal to pipeline 12. 
It is, of course, within the scope of this invention to use any number of 
pressurizable coal bins in this batch process embodiment. 
Another embodiment of the slurrying method and apparatus is illustrated in 
FIG. 3 and is designed to continually form the required pressurized slurry 
using a single pressurizable coal bin 140 equipped with stirring means 
141. In coal conduit 142 connecting coal storage 103 and bin 140 are two 
(or more) screw conveyors 143 and 144 of a type which permits a pressure 
drop to be maintained thereacross. These screw conveyors are pressure 
staged in order to provide coal under the desired pressure to bin 140 
e.g., at about 60-65 atmospheres. Pressurizing is conveniently carried out 
by using pressurized, boiled-off gaseous carbon dioxide from carbon 
dioxide storage vessel 113. The resulting pressurized coal and the 
pressurized liquid carbon dioxide are introduced simultaneously into bin 
140 for mixing and discharge into main slurry pipeline 12. 
The pressurized coal/liquid carbon dioxide slurry pumped through the main 
slurry pipeline 12 (FIG. 1A) should be maintained at a temperature between 
about -20.degree. C. and about 30.degree. C. and under a pressure between 
about 20 atmospheres and about 150 atmospheres. It will be appreciated 
that within these temperature and pressure ranges, the carbon dioxide is a 
liquid. Under these conditions there is no appreciable extraction by the 
liquid carbon dioxide of hydrocarbons, sulfur or other noncarbonaceous 
constituents from the coal. Moreover, coals containing an appreciable 
alkaline content are left unchanged in composition. Nor is any appreciable 
quantity of H.sub.2 CO.sub.3 formed which might present a chemical 
corrosion problem. 
Moreover, the finely divided coal does not agglomerate in liquid carbon 
dioxide, a fact which is in direct contrast to the situation which obtains 
in the case of coal/water slurries. Rather, the finely divided coal is 
easily dispersed in liquid carbon dioxide and remains dispersed during 
transport. The viscosity of a coal/liquid carbon dioxide slurry at about 
12.5.degree. C. is approximately one-tenth to one-thirtieth of that of a 
coal/water slurry at ambient temperature and at the same solids 
concentration, a fact which materially decreases the friction forces along 
the slurry pipeline. This, in turn, decreases the pressure drop and hence 
the power required to pump the slurry. Finally, coal can be loaded to a 
much higher weight percent level in liquid carbon dioxide than in water. 
For example, it can be loaded up to about 50% to about 55% percent by 
weight in water (i.e., one hundred pounds of slurry contains from about 50 
to 55 pounds of finely divided coal); whereas this figure can be as high 
as about 75 to about 80 in pounds of coal per 100 pounds of a coal/liquid 
carbon dioxide slurry. Generally, a loading range of between about 60% and 
80% by weight will be preferred in the practice of this invention. 
If the slurry pipeline 12 is of an appreciable length, e.g., more than 
several miles, it is preferably buried underground below the frostline to 
minimize problems of icing and/or relatively large variations in 
temperature with changing seasons. At such depths, the average ambient 
temperature is normally between about 10.degree. C. and about 16.degree. 
C., a temperature range essentially midway between the specified broad 
range of between about -20.degree. C. and 30.degree. C. It is, of course, 
possible to insulate the pipelines to maintain the slurry temperature at a 
level which is not in equilibrium with that of the ground in which it is 
laid. 
The velocity of the coal/liquid carbon dioxide slurry as it is pumped 
through the pipeline preferably ranges between about 1 and about 6 feet 
per second, the optimum velocity chosen depending upon such factors as 
coal composition, coal size distribution, ambient temperature, loading 
level, and the like. 
It will be necessary for any pipeline extending over a relatively long 
distance, e.g., over about 100 miles, to have one or more intermediate 
booster pumping stations 14 associated with it to maintain the desired 
pumping pressure and slurry velocity. Such pumping stations may also be 
used to provide any necessary adjustments in temperature, e.g., makeup 
refrigeration or added heat to the slurry through out-of-contact heat 
transfer with a suitable refrigeration system, e.g., liquid nitrogen, or 
with a suitable heat source such as combustion gases. 
Once the coal/liquid carbon dioxide slurry reaches the end of the pipeline, 
it is necessary to separate the carbon dioxide from the coal by 
deslurrying it at point 15 prior to its being placed in storage or to its 
transfer directly to a vessel. In deslurrying it is preferable that no 
appreciable amount of solid carbon dioxide is formed since it is not 
desirable to introduce this solid material into a storage elevator or into 
the compartments of a ship or barge. Thus, although it is possible to 
remove the carbon dioxide by merely releasing the pressure on the 
coal/liquid carbon dioxide slurry, this is not a preferable technique for 
deslurrying since it results in the formation of solid carbon dioxide with 
its attendant disadvantages in storage and/or separation. 
Since the slurry is a solid-liquid mixture, it is possible to use such 
conventional dewatering equipment as solid bowl centrifuges or 
liquid-solid cyclone separators operating under pressure to deslurry the 
coal. This method has the advantage of requiring a relatively small amount 
of energy to reliquefy any vaporized carbon dioxide before recycling. 
FIG. 4 diagrams a preferred method and apparatus for accomplishing the step 
of deslurrying. The apparatus will be seen to comprise a pressurized spray 
tower 150 having one or more spray heads 151, a supply of gaseous carbon 
dioxide 152 at a predetermined temperature in fluid communication through 
gas line 153 with the slurry pipeline 12, a cyclone separator 154 and a 
bag filter 155 (optional). A gas line 156 connects tower 150, cyclone 
separator 154 and bag filter 155. The deslurried coal from spray tower 
150, cyclone separator 154 and bag filter 155 is collected for pneumatic 
transport to storage elevators, or similar storage means, and/or to the 
waterborne carrier as described below. 
In operation of the deslurrying means of FIG. 4, the liquid carbon dioxide 
of the slurry is expanded to reduce the pressure to that level at which 
essentially all of the carbon dioxide will vaporize out of the slurry. 
Sufficient gaseous carbon dioxide at an elevated temperature is added to 
the slurry from carbon dioxide gas supply 152 prior to the introduction of 
the slurry into spray tower 150 to provide for at least a portion of the 
heat lost in the expansion of the slurry, thus preventing solidification 
of any appreciable amount of the carbon dioxide. Any solids remaining in 
the carbon dioxide withdrawn through line 156 are removed in the 
pressurized cyclone separator (of which there may be more than one) and in 
the bag filter, if included. These solids may be returned to the coal if 
desired. A portion of the gaseous carbon dioxide from filter 155 may be 
recycled through expander 157 and heater 158 to carbon dioxide gas supply 
152. As will be apparent from the following continued description of FIG. 
1, several options are available for handling the carbon dioxide, both 
liquid and gas, recovered in deslurrying. 
Returning now to FIG. 1A, all or a portion of the deslurried coal may be 
stored prior to loading on a waterborne carrier; or all of a portion of it 
may be loaded directly onto the carrier. The deslurried coal which is to 
be stored is pneumatically transported in line 16 to suitable coal storage 
means such as, for example, a series of elevators 17, 18 and 19, through 
line 20 with suitable branches 21, 22 and 23 controlled by valves 24, 25 
and 26. (It will be appreciated that the drawing in FIG. 1 using lines and 
valves represents a simplification of the system herein described and that 
it is designed to represent several different embodiments of the 
invention. The actual choice of lines, and means to control the flow of 
the various materials therethrough, is well within the skill of the art). 
Sufficient gaseous carbon dioxide is maintained in storage elevators 17-19 
to provide a protective blanket over the coal contained therein. The 
amount of carbon dioxide used will be determined by conventional practice 
for gas blanketing. The remaining gaseous carbon dioxide used in the 
pneumatic transport of the coal is withdrawn through lines 27, 28 and 29 
(the flow through which is controlled by valves 30, 31 and 32, 
respectively), and filters 33, 34 and 35 (which remove entrained coal) 
into a carbon dioxide recycle line 36 for recycling as a coal-carrying 
medium. Carbon dioxide gas resulting from the deslurrying step may also be 
used for this purpose as shown by line 37 of FIG. 1A. For the pneumatic 
pumping of the coal, it is dispersed in the gaseous carbon dioxide from 
whatever source as it flows through line 16. 
When stored coal is to be loaded onto the waterborne carrier 40, shown to 
have a series of compartments 41, 42 and 43, the appropriate valve 44, 45 
or 46, associated with coal elevators 17, 18 and 19, respectively, is 
opened to discharge the coal into vessel loading line 47. Carbon dioxide 
gas, from a source 48, is led into line 47, through line 49 and valve 50, 
to provide the carrier medium for the coal. Coal line 47 is movable from 
vessel compartment to compartment and it may be of such a length that the 
vessel may stand out from the harbor in deep water during loading. 
As in the case of land-based storage, the coal in the vessel compartments 
will have a protective blanket of carbon dioxide in essentially the same 
amounts, that required in standard practice. This necessitates the removal 
of the excess gaseous carbon dioxide from the compartments through a 
suitable line 51 which can lead back to the carbon dioxide gas supply 
means 48 for recycling. As shown in more detail in FIG. 5, each 
compartment may have a permanent gas line 52 incorporating a valve 53 and 
being sized and arranged for connecting, through adapter means 54, to main 
gas line 51 having a filter 55. 
If all or a portion of the deslurried coal pneumatically carried in line 16 
is to be loaded directly onto carrier 40, then the coal/gaseous carbon 
dioxide mixture is taken through line 60, having valve 61, directly to 
vessel loading line 47 and the appropriate valves in the lines running to 
and from the storage means are closed. The excess gaseous carbon dioxide 
is returned from the vessel compartments to carbon dioxide gas supply 
means 48 as previously described. 
It is, of course, within the scope of this invention to discharge all or a 
portion of the gaseous carbon dioxide into the atmosphere at any suitable 
point in the system. However it will generally be preferable to maintain 
the system as an essentially closed, recycling one, both to save any 
energy which might be required to generate the carbon dioxide lost by such 
discharging and to ensure that the environment associated with the system 
remains free from any coal dust. FIG. 1B also shows, through the use of 
dotted lines, the possible use of air, taken in through line 62, valve 63 
and compressor 64, as a carrier for the coal in vessel loading line 47. If 
air is used in this capacity then it may be discharged from the vessel 
compartments into the atmosphere after the coal particles are filtered 
out, and gas return line 51 may be eliminated. 
As will be seen from FIGS. 1A and 1B, the carbon dioxide recovered from 
deslurrying which is not used in pneumatically transporting the coal to 
storage or to the vessel may be handled in one or more of several ways. 
Thus it may be taken by valved line 70 to carbon dioxide gas supply 48, it 
may be carried by valve 71 to a use point, or it may be taken by valved 
line 72 to a liquefier 73 from where it may be conveyed through line 74 to 
a use point or through a liquid carbon dioxide pipe line 75, running 
parallel with coal/liquid carbon dioxide slurry pipeline 12, back to 
liquid carbon dioxide supply 11 at the coal source point for use in slurry 
formation at 10. At the coal source point, all or only makeup carbon 
dioxide may be supplied from a suitable source 77 and liquefied at 78 for 
use in slurry formation. 
The coal transport system of FIGS. 1A and 1B lends itself to well-known 
techniques to provide a partially or completely automated operation which 
may be, if desired, controlled by a suitably programmed computer. Such 
automated control may begin at the coal source point or at any desired 
point within the system. 
Once the waterborne carrier has reached its destination, the coal is 
unloaded and transported to a desired destination. As will be seen from 
FIGS. 6A and 6B, this may be a use point within the vicinity or nearby the 
unloading point, it may be a storage facility, or it may be a remote use 
point in which case the coal may be slurried with liquid carbon dioxide 
and moved through a pipeline. 
Gaseous carbon dioxide from a source 165 is introduced through line 166 
into a ship compartment 42 as a pneumatic carrier for the coal contained 
therein. The coal/gaseous carbon dioxide mixture is carried through line 
167 to one of several connecting lines. Thus the directions of flow shown 
in FIG. 5 are reversed, line 166 corresponding to line 51 and line 167 to 
line 47. Filter 55 is, of course, not used. Assuming first that the coal 
is to be stored at or near the harbor, the coal is carried through line 
168 to one of the coal storage elevators 169, 170 or 171 through branch 
conduit 172, 173 or 174 by proper actuation of valve 175, 176 or 177. 
These elevators are equipped with gaseous carbon dioxide discharge lines 
178, 179 and 180, having filters 181, 182 and 183 and being connected to 
carbon dioxide recycle line 184 going back to source 165. 
Coal is drawn from one or more of storage elevators 169, 170 or 171 through 
discharge valve means 185, 186 or 187 into coal delivery line 188 and is 
moved therethrough pneumatically with carbon dioxide from supply means 
189. Alternatively, air pumped in through line 190 by compressor 191 may 
be used. The coal/gaseous carbon dioxide mixture may then be delivered to 
a use point 195 from where all or part of the gaseous carbon dioxide may 
be recovered through line 196, having filter 197, and line 198 leading to 
gaseous carbon dioxide supply 189. This carbon dioxide may also be 
discharged through line 199 or taken by line 200 to a liquefier 201. 
If the ultimate use point for the coal is remote from the harbor and/or the 
coal storage means, then it may be taken as a coal/gaseous carbon dioxide 
mixture directly from the waterborne carrier via line 205, shown to have 
valve means 206, or from storage via delivery line 188 to a line 207 in 
fluid communication with coal slurrying means 208, such as illustrated in 
FIGS. 2 and 3. The gaseous carbon dioxide used in pneumatically 
transporting the coal to slurrying means 208 may be withdrawn through line 
209 and filter 210 to a liquefier 211 to provide the liquid carbon dioxide 
required to form a pumpable slurry. 
As described above, the slurry is then pumped through pipeline 215, using 
one or more booster pumping means 216 where necessary, to deslurrying 
means 217 associated with a use point. Liquid carbon dioxide may be 
returned by pipeline 218 to the slurry forming means 208 or it may be 
conveyed by line 219 to some use point. Likewise, any gaseous carbon 
dioxide in line 220 may be disposed of in any desired manner. 
Automatic control of all or a portion of the various embodiments of the 
coal unloading and disposition system of FIGS. 6A and 6B are also, of 
course, feasible. As in the case of loading the coal on the waterborne 
carrier, the unloading of it may be done while the carrier remains 
anchored in deep water. 
It will be seen that by transporting coal in finely divided particulate 
form using a unique combination of liquid and gaseous carbon dioxide it is 
possible to eliminate the need for a vast amount of complicated mechanical 
equipment heretofore required at coal-loading and unloading piers and to 
substitute for them lines which may be underground and which may even 
extend beyond the harbor to waterborne carriers anchored along the coast. 
The equipment required to load or unload a ship or barge in the practice 
of this invention--deslurrying or slurrying means, coal storage means and 
carbon dioxide storage and supply means--need not, in fact, be located at 
the pier, but can be placed in any suitable site. Moreover, because of the 
type of equipment used and the moving of the coal in fluid media, the 
method and equipment of this invention are particularly suited to 
automated operation. Finally, the system offers the possibility of being 
essentially pollution free. 
It will thus be seen that the objects set forth, among those made apparent 
from the preceding description, are efficiently attained and, since 
certain changes may be made in carrying out the above method and in the 
constructions set forth without departing from the scope of the invention, 
it is intended that all matter contained in the above description or shown 
in the accompanying drawings shall be interpreted as illustrative and not 
in a limiting sense.