Title:
METHOD OF PNEUMATICALLY CONVEYING COAL AND APPARATUS THEREFOR
United States Patent 3857490
Abstract:
A pneumatic conveyor system comprising an input duct through which particles of coal are drawn by a vacuum produced by a paddle wheel - like impeller positioned behind the input duct. A screen is positioned between the impeller and the input duct which separates the finer from the coarser particles. The finer particles are allowed to pass through the screen, into the impeller and are then jetisoned out the opposite side into an exhaust duct. The coarser particles are deflected downward by the screen and are collected in the housing below the impeller. A series of these pneumatic conveyors can be linked together so that the impeller of one conveyor provides the suction for the previous conveyor to remove the coarser particles from the bottom of the previous conveyor to the input duct of a subsequent conveyor causing them to impinge upon the screen of that conveyor and thus removing additional fine particles. The exhaust duct of one conveyor which carries the finer particles, is attached to the exhaust duct of the subsequent conveyor thus transferring the fine particles from conveyor to conveyor, separate from the coarser particles. As many of these conveyors as are desired may be utilized to move coal from one location to another.
US Patent References:
Combined boll-cotton beating, cleaning, vacuum, and dropping machine
Noisworthy - September 1930 - 1775599
Cotton cleaner
Rust - January 1944 - 2339295
Apparatus for mining coal
Reeder - May 1945 - 2375689
Combined boll-cotton beating, cleaning, vacuum, and dropping machine
Noisworthy - September 1930 - 1775599
Cotton cleaner
Rust - January 1944 - 2339295
Apparatus for mining coal
Reeder - May 1945 - 2375689
Application Number:
05/323700
Publication Date:
12/31/1974
Filing Date:
01/15/1973
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
299/18, 299/8
International Classes:
B07B7/06; B65G53/14; B65G53/60; B07B7/00; B65G53/04; B65G53/34; B01D46/12
Field of Search:
209/250,355 299/7,8,18 302/23,28,58,59
Primary Examiner:
Blunk, Evon C.
Assistant Examiner:
Carson, Scott W.
Attorney, Agent or Firm:
Cushman, Darby & Cushman
Claims:
I claim
1. A pneumatic coal conveying system comprising: a plurality of spaced housings disposable within a mine shaft and interconnected so as to extend from a position adjacent the face of the shaft from which coal is being removed to a remote location;
2. A pneumatic coal conveyor as defined in claim 1 wherein a casing is provided around a portion of said impeller means sealing off said impeller means from said housing except for said screen means and providing a passage from said impeller means to said exhaust duct.
1. A pneumatic coal conveying system comprising: a plurality of spaced housings disposable within a mine shaft and interconnected so as to extend from a position adjacent the face of the shaft from which coal is being removed to a remote location;
2. A pneumatic coal conveyor as defined in claim 1 wherein a casing is provided around a portion of said impeller means sealing off said impeller means from said housing except for said screen means and providing a passage from said impeller means to said exhaust duct.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a means for conveying coal from the point where it is mined within a mine shaft to a remote location, and more particularly to a pneumatic-type of coal conveyor wherein the particles of coal are transferred to the remote location by suspension in a stream of air.
2. Prior Art
Many means have been devised for removing coal from the area directly adjacent to where it is being mined to some remote area where it may be more easily handled. Such devices have been provided for safety reasons as well as commercial expediency in handling the mined coal. It has been known for a considerable length of time that the minute particulate matter which is produced by the mining of coal, when suspended in the air inside the mine shaft creates a highly explosive condition. Thus, many devices which have been designed for removing coal from the mining area had the removal of such minute particulate matter as a primary goal in their design.
One of the more practical means of reducing the amount of particulate matter in the area surrounding the mining is to use a pneumatic system employing principles similar to a vacuum cleaner. Such a device is disclosed in U.S. Pat. No. 2,375,689. It is to be noted that this particular device is to be utilized for the containment of pulvarized coal and that the fan-type propeller arrangement utilized therein is actually intended to so pulverize the larger particles of coal being mined. Such a device is common in that it utilizes a fan-type of propeller blade directly in the line of coal transmission and rotating perpendicular thereto, thus requiring the coal to pass through the fan blade at right angles to the direction of rotation of the fan so that it must strike the blades. Unless the fan is designed for such severe treatment, it will be quickly worn out by the abrasive action of the stream of coal passing through it. Another similar type of fan-blade propeller device is shown in U.S. Pat. No. 1,385,447.
Because of the difficulty of using such a device with particles of greater than miniscule dimensions, conveyors of the type shown in the U.S. Pat. No. 1,227,128 were devised which provide impeller blades adjacent to an opening in a duct, thus creating a suction in order to draw the particulate material through the duct and subsequently propel it beyond the impellers through an output duct. Such devices are relatively larger in size, and due to the indirect effect of the impeller - created suction, are fairly inefficient.
Additionally, it is to be noted that all of the types of devices described above for use in conveying coal in particulate form are incapable of separating the finer particles of coal which create the explosive hazzard from the larger granular material which is the commercially usable product.
One of the major difficulties with the fan-type impeller is that the blades rotate in a direction substantially perpendicular to the direction of air and particle flow as mentioned above. Such a condition will result in either the impeller being damaged or the particles will be pulverized as a result of the impact with the impeller. In instances where it is not desirable to reduce the granular size of the particles, it is not advantageous to use such a system. In such a case, the second method referred to above, i.e., such as that disclosed in the U.S. Pat. No. 1,227,128 could be utilized. However, in addition to its reduced efficiency, there is still no means for separating the finer particles from the coarser particles. As a result of such inability to separate the particles of different density, it is generally necessary to wash the coal after it has been removed from the mine in order to remove the amount of dust attached to the coarser particulate material. It should be noted that this then naturally adds an additional step of drying the coal before it can be commercially used.
SUMMARY OF THE INVENTION
The present invention overcomes the above-described difficulties by providing a pneumatic conveyor which can be utilized within the mine shafts adjacent to the face where the coal is being mined and which may be extended as far through the tunnel system as is desired to remove the coal therefrom. The present invention also separates the finer particulate material from the coarser particles thereby reducing or eliminating the steps of washing and drying the coal after it has been mined.
The apparatus of the present invention basically comprises a housing having an input duct, exhaust duct, and an output duct, and which housing further contains an impeller for incuding an airflow in said input duct and said exhaust duct. The impeller is positioned between the input duct and the exhaust duct and a screen is disposed between the impeller and the input duct. The invention can be utilized in series whereby the input duct of a first conveyor is extended directly to the area adjacent the mining of the coal and thereby accumulates the particles of coal mined and conveys them to the housing where they impinge upon the screen which in turn allows the smaller particles to proceed through the screen into the impeller and out the exhaust duct, and which screen prevents the coarser particles from proceeding therethrough thus causing them to be deflected to the lower portion of the housing wherefrom they are removed through the output duct by suction. The suction on the output duct can be provided by the next adjacent conveyor by attaching the output duct of the first conveyor to the input duct of the next conveyor, and so on, in series, for as many conveyors as is desired to remove the coal from the place where it is being mined to a remote location.
The impeller is a paddle-wheel like member which in addition to producing air flow, thus creating a suction, can transfer the finer particulate matter which comes through the screen to the exhaust duct without appreciable damage since the impeller is moving in a direction parallel to the flow of particulate matter.
The screen, which is positioned between the impeller and the input duct is parallel to the impeller but at an angle to the duct so that larger particles of coal which impinge on the screen are deflected downward into the bottom of the housing. An additional advantage of the present pneumatic coal conveyor in comparison to hydraulic types of conveyors is that the screening system here utilized will not be as easily clogged since it is a common problem with such systems that the coal mixes with whatever fluid (such as water) is being utilized and creates a paste-like mixture which tends to clog the screen, reducing its effectiveness for separating the particles.
The method of the present invention can be practiced with suitable apparatus such as that disclosed in the present application and basically includes the steps of:
1. vacuuming the coal by means of an air stream away from the vein where it is being mined,
2. transporting the coal to a location remote from the vein,
3. separating larger particles of coal from smaller particles and allowing the smaller particles to travel on while the larger particles are collected,
4. vacuuming the larger particles away by a second air stream, and
5. transporting the larger particles away in the second air stream.
By referring to the description of the apparatus of the present invention and how it functions, the basic steps of the method can be easily followed and, therefore, further clarification is believed to be unnecessary.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic elevation view, illustrating the preferred positioning of the parts in the pneumatic coal conveyor apparatus of the present invention.
FIG. 2 is a pictorial schematic elevation view showing a portion of a mine tunnel with a mining apparatus in position and a series of pneumatic coal conveyors of the present invention extending through the tunnel.
DETAILED DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the conveyor is schematically illustrated in FIG. 1, and comprises essentially an impeller 10, a housing 12 an input duct 14, an output duct 16 an exhaust duct 18 and a screen member 20.
Impeller 10 is positioned between input duct 14 and exhaust duct 18 so as to create a flow of air from input duct 14 to output duct 18. Impeller 10 is preferably a paddle-wheel like member constructed with a series of vanes which extend perpendicular to the direction of air flow previously indicated.
Screen 20 is positioned in front of the input duct 14 and is disposed at an angle such that particles impinging thereon, as they exit from input duct 14, will be deflected to the lower portion of housing 12. Screen 20 is attached at its lower portion to a cage-like member 22 which substantially surrounds impeller 10 except for the openings created by screen 10 and exhaust duct 18. Member 22 should be attached to housing 12 to prevent air flow and thus particle flow, from the impeller directly into the housing.
A limit switch 17 can be positioned in housing 12, at the entrance of exhaust duct 16, so as to provide a means for automatically stopping impeller 10 when an excess of large particulate material accumulates in exhaust duct 16 so as to clog and prevent air flow therethrough. Such a switch may be utilized to not only stop impeller 10 but to also shut down the coal digging apparatus as well until the system has been cleared.
Referring now to the manner in which the invention functions, as some type of digging apparatus 26, as is shown in FIG. 2, removes coal from the face of a mine shaft it produces fine-grained dust-like particles as well as the coarser particles of the size which the apparatus 26 is intended to produce as it removes the coal from the source. Both the fine and coarse grained particulate material are removed from the digging apparatus 26 by a vacuum created in input duct 14, all of which material impinges upon screen 20 as it first enters housing 12. The mesh, i.e., the dimensions of the holes in the screen 20, will determine the size of the particulate material which will be allowed to pass through screen 20, and thus, be conveyed by impeller 10 to exhaust duct 18. It should be noted, however, that although a fine mesh is desirable for the removal of only the dust-like particles, a fine mesh will also tend to clog faster than a coarser mesh so that the mesh selected should be coarse enough to only prevent those large particles being mined from entering the exhaust duct 18.
The coarser particles which are not allowed through screen 20 are deflected into the lower portion of housing 12 and are picked up in the air flow created in duct 16 by a subsequent impeller attached thereto and which will be described below.
Cage-like member 22 is provided to prevent the finner particulate matter which passes through screen 20 from continuing on around impeller 10 and proceeding out through output duct 16. Cage 22 therefore, must be a solid member which is attached to housing 12 and provides a substantially complete enclosure for impeller 10 except for the opening provided for screen member 20 and exhaust duct 18.
FIG. 2 illustrates the manner in which the pneumatic conveyor of the present invention is utilized in series with other identical units of the conveyor in order to provide a means for transferring the particulate material, both fine and coarse, from the face of the mine where it is being excavated. The pneumatic coal conveyors 28, 30 and 32 are indicative of the manner in which such conveyor systems may be connected together to form a substantially longer conveyor which can extend to some other part of the mining tunnel and even to the surface where it may be transported by truck or some other system to be utilized or further processed.
A digging apparatus 34 can be adapted to be directly attached to an input duct 14 whereupon the particulate matter vacuumed into the duct, as a result of the suction created by impeller 10, will be transported therethrough and into the first pneumatic conveyor 28 which operates in the manner previously described with reference to FIG. 1. Thereupon the finer particulate matter is separated out from the coarser material in the manner also previously described, and the finer particles are propelled along the exhaust duct 18 by the vacuum created by the impeller in conveyor 30. In the same manner, the coarser particles are propelled through output duct 16 and are moved therethrough by the vacuum created by the impeller in conveyor 30. This process continues for as many pneumatic conveyor units as are utilized, and additionally, since the coarser particles which move through the series of conveyors impinge upon screen 20 in each such conveyor additional fine particulate matter not previously removed may then be added to the flow of finer particulate material being propelled through duct 18. Therefore, the more units that are utilized in series the greater the possibility of removing all of the fine particulate matter which is an undesirable by-product of the mining process so far as the commercial value of the coarser particulate material is concerned.
Although the foregoing description illustrates the preferred embodiment of the present invention and the method of practice thereof, it will be apparent to those skilled in the art that variations are possible. All such variations as would be obvious to those skilled in this art are intended to be included within the scope of this invention.
1. Field of the Invention
This invention relates to a means for conveying coal from the point where it is mined within a mine shaft to a remote location, and more particularly to a pneumatic-type of coal conveyor wherein the particles of coal are transferred to the remote location by suspension in a stream of air.
2. Prior Art
Many means have been devised for removing coal from the area directly adjacent to where it is being mined to some remote area where it may be more easily handled. Such devices have been provided for safety reasons as well as commercial expediency in handling the mined coal. It has been known for a considerable length of time that the minute particulate matter which is produced by the mining of coal, when suspended in the air inside the mine shaft creates a highly explosive condition. Thus, many devices which have been designed for removing coal from the mining area had the removal of such minute particulate matter as a primary goal in their design.
One of the more practical means of reducing the amount of particulate matter in the area surrounding the mining is to use a pneumatic system employing principles similar to a vacuum cleaner. Such a device is disclosed in U.S. Pat. No. 2,375,689. It is to be noted that this particular device is to be utilized for the containment of pulvarized coal and that the fan-type propeller arrangement utilized therein is actually intended to so pulverize the larger particles of coal being mined. Such a device is common in that it utilizes a fan-type of propeller blade directly in the line of coal transmission and rotating perpendicular thereto, thus requiring the coal to pass through the fan blade at right angles to the direction of rotation of the fan so that it must strike the blades. Unless the fan is designed for such severe treatment, it will be quickly worn out by the abrasive action of the stream of coal passing through it. Another similar type of fan-blade propeller device is shown in U.S. Pat. No. 1,385,447.
Because of the difficulty of using such a device with particles of greater than miniscule dimensions, conveyors of the type shown in the U.S. Pat. No. 1,227,128 were devised which provide impeller blades adjacent to an opening in a duct, thus creating a suction in order to draw the particulate material through the duct and subsequently propel it beyond the impellers through an output duct. Such devices are relatively larger in size, and due to the indirect effect of the impeller - created suction, are fairly inefficient.
Additionally, it is to be noted that all of the types of devices described above for use in conveying coal in particulate form are incapable of separating the finer particles of coal which create the explosive hazzard from the larger granular material which is the commercially usable product.
One of the major difficulties with the fan-type impeller is that the blades rotate in a direction substantially perpendicular to the direction of air and particle flow as mentioned above. Such a condition will result in either the impeller being damaged or the particles will be pulverized as a result of the impact with the impeller. In instances where it is not desirable to reduce the granular size of the particles, it is not advantageous to use such a system. In such a case, the second method referred to above, i.e., such as that disclosed in the U.S. Pat. No. 1,227,128 could be utilized. However, in addition to its reduced efficiency, there is still no means for separating the finer particles from the coarser particles. As a result of such inability to separate the particles of different density, it is generally necessary to wash the coal after it has been removed from the mine in order to remove the amount of dust attached to the coarser particulate material. It should be noted that this then naturally adds an additional step of drying the coal before it can be commercially used.
SUMMARY OF THE INVENTION
The present invention overcomes the above-described difficulties by providing a pneumatic conveyor which can be utilized within the mine shafts adjacent to the face where the coal is being mined and which may be extended as far through the tunnel system as is desired to remove the coal therefrom. The present invention also separates the finer particulate material from the coarser particles thereby reducing or eliminating the steps of washing and drying the coal after it has been mined.
The apparatus of the present invention basically comprises a housing having an input duct, exhaust duct, and an output duct, and which housing further contains an impeller for incuding an airflow in said input duct and said exhaust duct. The impeller is positioned between the input duct and the exhaust duct and a screen is disposed between the impeller and the input duct. The invention can be utilized in series whereby the input duct of a first conveyor is extended directly to the area adjacent the mining of the coal and thereby accumulates the particles of coal mined and conveys them to the housing where they impinge upon the screen which in turn allows the smaller particles to proceed through the screen into the impeller and out the exhaust duct, and which screen prevents the coarser particles from proceeding therethrough thus causing them to be deflected to the lower portion of the housing wherefrom they are removed through the output duct by suction. The suction on the output duct can be provided by the next adjacent conveyor by attaching the output duct of the first conveyor to the input duct of the next conveyor, and so on, in series, for as many conveyors as is desired to remove the coal from the place where it is being mined to a remote location.
The impeller is a paddle-wheel like member which in addition to producing air flow, thus creating a suction, can transfer the finer particulate matter which comes through the screen to the exhaust duct without appreciable damage since the impeller is moving in a direction parallel to the flow of particulate matter.
The screen, which is positioned between the impeller and the input duct is parallel to the impeller but at an angle to the duct so that larger particles of coal which impinge on the screen are deflected downward into the bottom of the housing. An additional advantage of the present pneumatic coal conveyor in comparison to hydraulic types of conveyors is that the screening system here utilized will not be as easily clogged since it is a common problem with such systems that the coal mixes with whatever fluid (such as water) is being utilized and creates a paste-like mixture which tends to clog the screen, reducing its effectiveness for separating the particles.
The method of the present invention can be practiced with suitable apparatus such as that disclosed in the present application and basically includes the steps of:
1. vacuuming the coal by means of an air stream away from the vein where it is being mined,
2. transporting the coal to a location remote from the vein,
3. separating larger particles of coal from smaller particles and allowing the smaller particles to travel on while the larger particles are collected,
4. vacuuming the larger particles away by a second air stream, and
5. transporting the larger particles away in the second air stream.
By referring to the description of the apparatus of the present invention and how it functions, the basic steps of the method can be easily followed and, therefore, further clarification is believed to be unnecessary.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic elevation view, illustrating the preferred positioning of the parts in the pneumatic coal conveyor apparatus of the present invention.
FIG. 2 is a pictorial schematic elevation view showing a portion of a mine tunnel with a mining apparatus in position and a series of pneumatic coal conveyors of the present invention extending through the tunnel.
DETAILED DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the conveyor is schematically illustrated in FIG. 1, and comprises essentially an impeller 10, a housing 12 an input duct 14, an output duct 16 an exhaust duct 18 and a screen member 20.
Impeller 10 is positioned between input duct 14 and exhaust duct 18 so as to create a flow of air from input duct 14 to output duct 18. Impeller 10 is preferably a paddle-wheel like member constructed with a series of vanes which extend perpendicular to the direction of air flow previously indicated.
Screen 20 is positioned in front of the input duct 14 and is disposed at an angle such that particles impinging thereon, as they exit from input duct 14, will be deflected to the lower portion of housing 12. Screen 20 is attached at its lower portion to a cage-like member 22 which substantially surrounds impeller 10 except for the openings created by screen 10 and exhaust duct 18. Member 22 should be attached to housing 12 to prevent air flow and thus particle flow, from the impeller directly into the housing.
A limit switch 17 can be positioned in housing 12, at the entrance of exhaust duct 16, so as to provide a means for automatically stopping impeller 10 when an excess of large particulate material accumulates in exhaust duct 16 so as to clog and prevent air flow therethrough. Such a switch may be utilized to not only stop impeller 10 but to also shut down the coal digging apparatus as well until the system has been cleared.
Referring now to the manner in which the invention functions, as some type of digging apparatus 26, as is shown in FIG. 2, removes coal from the face of a mine shaft it produces fine-grained dust-like particles as well as the coarser particles of the size which the apparatus 26 is intended to produce as it removes the coal from the source. Both the fine and coarse grained particulate material are removed from the digging apparatus 26 by a vacuum created in input duct 14, all of which material impinges upon screen 20 as it first enters housing 12. The mesh, i.e., the dimensions of the holes in the screen 20, will determine the size of the particulate material which will be allowed to pass through screen 20, and thus, be conveyed by impeller 10 to exhaust duct 18. It should be noted, however, that although a fine mesh is desirable for the removal of only the dust-like particles, a fine mesh will also tend to clog faster than a coarser mesh so that the mesh selected should be coarse enough to only prevent those large particles being mined from entering the exhaust duct 18.
The coarser particles which are not allowed through screen 20 are deflected into the lower portion of housing 12 and are picked up in the air flow created in duct 16 by a subsequent impeller attached thereto and which will be described below.
Cage-like member 22 is provided to prevent the finner particulate matter which passes through screen 20 from continuing on around impeller 10 and proceeding out through output duct 16. Cage 22 therefore, must be a solid member which is attached to housing 12 and provides a substantially complete enclosure for impeller 10 except for the opening provided for screen member 20 and exhaust duct 18.
FIG. 2 illustrates the manner in which the pneumatic conveyor of the present invention is utilized in series with other identical units of the conveyor in order to provide a means for transferring the particulate material, both fine and coarse, from the face of the mine where it is being excavated. The pneumatic coal conveyors 28, 30 and 32 are indicative of the manner in which such conveyor systems may be connected together to form a substantially longer conveyor which can extend to some other part of the mining tunnel and even to the surface where it may be transported by truck or some other system to be utilized or further processed.
A digging apparatus 34 can be adapted to be directly attached to an input duct 14 whereupon the particulate matter vacuumed into the duct, as a result of the suction created by impeller 10, will be transported therethrough and into the first pneumatic conveyor 28 which operates in the manner previously described with reference to FIG. 1. Thereupon the finer particulate matter is separated out from the coarser material in the manner also previously described, and the finer particles are propelled along the exhaust duct 18 by the vacuum created by the impeller in conveyor 30. In the same manner, the coarser particles are propelled through output duct 16 and are moved therethrough by the vacuum created by the impeller in conveyor 30. This process continues for as many pneumatic conveyor units as are utilized, and additionally, since the coarser particles which move through the series of conveyors impinge upon screen 20 in each such conveyor additional fine particulate matter not previously removed may then be added to the flow of finer particulate material being propelled through duct 18. Therefore, the more units that are utilized in series the greater the possibility of removing all of the fine particulate matter which is an undesirable by-product of the mining process so far as the commercial value of the coarser particulate material is concerned.
Although the foregoing description illustrates the preferred embodiment of the present invention and the method of practice thereof, it will be apparent to those skilled in the art that variations are possible. All such variations as would be obvious to those skilled in this art are intended to be included within the scope of this invention.