US3784256A

US3784256A - Dust control in longwall mining

Info

Publication number: US3784256A
Application number: US00258563A
Authority: US
Inventors: J Katlic
Original assignee: Allied Chemical Corp
Current assignee: Honeywell International Inc
Priority date: 1972-06-01
Filing date: 1972-06-01
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: GB1408099A; AU5640173A; DE2326168A1; FR2186858A5

Abstract

Method and apparatus for removing dust ladened air from the vicinity of a moving mining machine engaged in longwall mining, wherein a conduit maintained at reduced pressure is parallel and fixedly positioned with respect to the path of operation of the longwall mining machine, and the machine activates ports in the section of the conduit adjacent to the mining machine irrespective of the location of the machine within its field of locomotion. The air is exhausted from the conduit and directed to the fallen roof area of the mine.

Description

o ilmted States Patent 1191 1111 3,784,256 Katlic 14 1 Jan. 8, 1974 [5 DUST CONTROL IN LONGWALL MINING 3,700.284 10/1972 Agnew 299/12 x [75] Inventor: John E. Kath-c, Mad1son, NJ. Primary Examiner-Erhest R. Purser [73] Assignee: Allied Chemical Corporation, New Att0rney-Gerard P. Rooney et al.

York; NY. 22 Filed: June 1, 1972 [57] ABSTRACT Method and apparatus'for removing dust ladened air [21 1 Appl' 258563 -from the vicinity ofa moving mining machine engaged in longwal] mining, wherein a conduit maintained at 52-1 U.S. (:1. 299/12, 299/43 reduced Pressure is parallel and fixedly positioned 511 lm. c1. E2lc 35/22 with respect to the P Of Operation of the lengwall [58] Field of Search 299/12, 43-46 mining machine. and the machine activates ports in the section of the conduit adjacent to the mining ma- [5 Reference-S Cited chine irrespective of the location of the machine UNITED STATES PATENTS within its field of locomotion. The air is exhausted 3 225 678 2/1965 D 299/12 X from the conduit and directed to the fallen roof area ensmore 3,7l2,678 1/1973 Amoroso of the 2,749,105 6/1956 Sibley 299/!2 X 25 Claims, 8 Drawing Figures DIRECTION or MINING OPERATION PATH c} OPERATION OF SHEARER-LOADER FATENTEDM 8 19m SHEET 1 BF 8 1 6 zoEEmmo 292506 to ICE @225 lo zoFQmEQ AmxUOIQV mPKOnEDm uOOm PATENTEU JAM 81374 SHEET 2 0? 8 PMENTED 3.784256 saw 7 0F 8 TO 608 OR T DUST COLLECTOR DUST COLLECTOR TO 608 OR PMENTED JAN 81974 SHEEI 8 BF 8 11' DUST CONTROL IN LONGWALL MINING BACKGROUND OF THE INVENTION l. FIELD OF THE INVENTION This invention relates to a method of removing dust in mines, particularly that produced by mining machines, and by the movement of roof supporting chocks as employed in the longwall mining of underground coal and mineral deposits.

ll. DESCRIPTION OF THE PRIOR ART Dust formation in mines has long been recognized as a serious problem, and many different methods are employed to reduce the concentration of suspended dust in the air. In coal mines, dust is particularly dangerous because of the possibility of dust explosions, and in all mines itconstitutes a serious threat to the miners who must contend with it. I

With the advent of longwall mining methods the problem has increased because of the rapidity of the mining operation, and the vigor with which rotary ranging drums of shearer-loaders, and the picks of longwall plows, bite into-the column being mined.

Briefly, longwall mining is practiced by driving parallel entries into the mineral formation to be mined, connecting the entries with one or more primary passages, thereby defining a mainpillar to be mined, supporting the roof of a primary passage by means of movable roof supports or chocks," mining the exposed face of the main pillar under the protection of the roof supporting structures, removing the mined material and advancing the supporting structure so that it remains adjacent and parallel to the mine face as it recedes.

As the chocks are moved toward the receding mine face, they leave an area without roof support. The unsupported roof collapses, and often the floor heaves to fill the space with broken pieces of rock such as shale. The collapsed material in the fallen roof area is known as gob."

In longwall mining a mining machine such as a shearer-loader having power driven rotary toothed drums, or a plow with extending picks, passes back and forth before the mine face, removing a quantity of the material being mined at each pass. The mined material falls into a face conveyor" which is adjacent and parallel to the longwall, and is moved at intervals as the wall recedes. The conveyor continuously removes the loose material as it is mined from the longwalLand generally the conveyor guiderails serve as a track forthe mining machine in its travel before the longwall, usually a distance of about 400 to 600 feet. v

The relatively narrow passageway between the face conveyor and the gob which is protected by the roof supporting chocks serves as a man-way. In order to deflect that portion of the falling mined material (which' would otherwise drop into the manway), back to the conveyor, a relatively high separating plate is placed between the conveyor and the man-way known as the spill-plate. This spill-plate, which is generally a part of the conveyor assembly, frequently includes more than just the barrier. It usually has a rectangular cross section with the side toward the longwall being the highest, and acting as the deflecting plate. This long structure serves to house power cables for the longwall system, and includes a trough, one side of which serves as the deflector. This trough carries the power cable and water hose attached to the mining machine, accepting and playing it out, as the moving machine requires. In

spill plate assemblies of this design there is often wasted space, either between the cable carrying conduit and the trough, or beneath both. As the machine cuts into the longwall, considerable dust is generated, and this is partially controlled by water sprays employed at the point of cutting. Considerable dust is also generated by the movement of the roof supporting members, or chocks.

Individual fans are often placed along the route of the mining machine, but none of these precautions are entirely satisfactory. Not only are such fans not adequate for the job to be performed, but the sound level they produce at the point where the mining operation is progressing, is highly undesirable. This is especially true in view of the limited space within which the operating personnel are required to work. While it is required that the amount of dust associated with longwall mining be significantly and progressively reduced, the means to achieve this reduction to the necessary degree, are not now available to the mining industry.

SUMMARY OF THE INVENTION I have now found a method of effectively removing dust ladened air from the immediate vicinity of the mining machine, including the area within which dust is generated by the movement of the roof supporting chocks, and to do this with a minimum of sound production. A rigid conduit is positioned parallel to the path of operation of the mining machine, and the pressure reduced within by the connection thereto of the intake of at least one device for moving large volumes of air. Preferably, a motor driven centrifugal blower of large capacity is connected to one end of the conduit whereas the other is blankedoff, or alternately, a blower is connected to each end of the conduit. If this is done, it is preferable to divide the conduit in two sec tions by a partition or other means, with one blower servicing one section.

Ports are placed along the wall of the rigid conduit covered with coverplates o r flaps, normally in a closed position with respect to the port, but capable of being activated or opened by the mining machine as it approaches, being maintained in the open position while the mining machine is adjacent, and closed or released by the machine when it is .no longer adjacent. The dust ladened air at atmospheric pressure flows into the open ports at the point where the dust is being generated. This is true not only of thedust generated by the mining machine, but by the movement of the roof machine passes.

A special feature of this invention is that the conduit can be designed into the spill plate assembly previously described, and the spill plate assembly can be increased in size both in height and cross section without detriment, to provide a conduit of sufficient cross section to be highly effective. A suitable conduit can preferably be incorporated into the spill plate assembly, using the bottom of the trough generally used for accepting and playing out power cable and water hose to the mining machine as the top of the conduit, the top of the passageway carrying the power cables as the bottom of the conduit, and the spill plate and adjacent plate which completes the structure as the two sides of the conduit. Of course, other arrangements may be used if desired, to secure the desired conduit or air passage. The conduit preferably has a cross sectional area of at least about I28 sq. in.. as would be obtained by a cross section of 8 X l6 inches, but the greater the area of the cross section, and the greater the freedom from inter nal obstructions, the greater the effectiveness of the system.

One embodiment of my invention includes the placement of at least one dust collecting device between the blower and the point where the air is to be discharged, preferably into the gob. This will further reduce the dust, the hazards associated therewith, and in some instances will provide a dust, such as coal dust, having some economic value. Whether or not dust collecting devices are included in the system, it is preferable that the air exhausted from the system be conducted into the fallen roof area or gob.

There are many ways in which the ports may open or be activated. They may swing in, swing out, lift up, slide right, left. or down. They may consist of long plates or flaps, or they may be small louver boards covering slots, or overlapping, to open or close, venetian blind fashion. depending on the need for local dust removal. They may operate electrically by photoelectric control depending on the dust density for activation, or more inexpensively, by mechanical movement based on the approach and departure of the mining machine along its path of operation.

In the accompanying illustrations various flaps are shown of simple design, easily removed for cleaning or maintenance and mechanically activated in simple fashion. Designs are shown wherein the dust in the conveyor may be sprayed with water, and the conduit can be flushed free of dust deposits by an internal water spray, without, if desired, even removing the flaps.

Finally, in one embodiment perforations in the flaps or in the conduit wall adjustable or fixed effective cross sectional area are included, so that a degree of dust collection can be had throughout the length of the conduit independent of the moving spot draft or ventilation which is achieved in the preferred embodiment of my invention.

DESCRIPTION OF THE DRAWINGS This description is directed to the accompanying drawings wherein like reference characters refer to like parts throughout the several views.

FIG. 1 is a perspective view illustrating the manner in which the conduit of the present invention may be adpated to the removal of dust ladened air in the longwall mining of underground mineral deposits. A preferred method of positioning the conduit with respect to the mining machine, face conveyor and spill plate is shown. The diagramatic representation of one end of the mining machine is presented in this instance as a shearer-loader. The conduit is an integral part of the spill plate which also is shown as providing a passageway for the required electrical power cables for the longwall mining system, and atrough for the take-up of electrical cables and water hose to the shearer-loader. A shoe extending from the mining machine is depicted in the act of activating the adjacent flaps, in the near face of the conduit, to their open position. Those flaps not adjacent to the machine are shown in their normally closed position. Also shown, is one of several types of shields which may if desired, be attached to the mining machine to overhang the open flaps when ofthe top opening variety, to prevent large pieces of mined material entering the open ports in the conduit, Alternately, a shield can be affixed to the spill plate throughout its length as shown in FIG. 4.

FIG. 2 is a break-away perspective view of a modification of the flap arrangement of the conduit of FIG. 1. The flaps when pressed, move inwardly to admit the surrounding dust ladened air into the zone of lower pressure. Spring biasing means are shown, having sufficient strength to retain the flaps in their normally closed position against the pressure differential which tends to open them. Also shown are three modifications of the member extending from the mining machine, to exert the activating force against the flaps.

FIG. 3 is a perspective view of another modification of the flap arrangement of the conduit of FIG. 1. One of the plates is shown as foraminous to allow the collection of dust ladened air. When all the plates are perforate, dust ladened air is drawn into the conduit throughout its entire length at all times when the system is in operation. These flaps are designed so as to regain their closed position by gravity, and are not dependent on the pressure differential to maintain them in the closed position. One flap has been removed to show its design. Also shown is one modification of the bearing surface of the support member. Since the bearing surface in this embodiment accepts the rotating pivot of two adjacent plates, it may be fully or partially divided, thus centering the flaps more precisely within their area of operation, and preventing the edge of one flap from interfering with the edge of the adjacent flap. This figure also presents a cross sectional view of a conduit similar to that above, with the exception that the floor of the conduit slopes slightly downward toward the bottom edge of the flaps. A cross section of a pipe is also shown, extending the length of the conduit, and containing perforations or jets, so that water can be passed therethrough to wet down dust or flush dust or particulate accumulations out of the conduit.

FIG. 4 is a perspective view of still another modification ofthe conduit of FIG. I. The flaps open at the top, and therefore require bias to close. This bias may be supplied by various means such as by springs, or by shifting the center of gravity so that the flaps rotate to the closed position when free to move. A flap, weighted so as to shift the center of gravity, is shown. The weight, being parallel to the air stream within the conduit, offers little obstruction to its flow. Since the machine preferably includes an extending member to close the flaps as it passes beyond them, the pressure differential will keep them closed when the system is in operation. When there is no pressure differential as during shut down, latches can be included, as shown, to retain the flaps in the closed position. Also shown in this drawing is one of several different types of shields that may be attached to the spill plate, if necessary, to prevent chunks of mined material from entering the conduit when outwardly opening flaps are used.

FIG. 5 is a perspective view of a modification of the conduit of FIG. 4 in which the pivot point of each flap is placed a sufficient distance forward, so that the center of gravity will fall behind the pivot point even when the flap is in the open position, thus causing it to rotate by gravity from the open position to the closed position. The design of one of the easily removable flaps is shown.

FIG. 6 represents an elevated cross sectional view of the conduit of FIG. 5 taken through line 6-6, both with the flap in the open and closed position. A memher extending from the machine is indicated, forcing the flap into the open position. Also shown is a type of shoe which may be attached to the machine to move an unbiased flap from the open to the closed position.

FIG. 7 is a diagramatic representation of the conduit of FIG. 1 with a device at each end for exhausting air from the conduit for transmission to a selected area. In this instance, rotary centrifugal blowers are used, and the air is transmitted to the fallen roof area, or gob." A flexible conduit is shown between the conduit and blowers. Although not necessary, it is preferable so as to minimize the transmission of vibration from the blowers, and to permit the placement of the blowers at any selected point. Where blowers are used to service both ends of the conduit, it is preferable to divide the conduit into two independent sections by a dividing partition or other means, therebymaintaining the reduced pressure in each section by means of the device for moving large volumes of air, such as a motor driven centrifugal blower, connected thereto.

FIG. 8 is a diagramatic representation of the conduit and the blower assembly of the present invention, but with a dust collector interposed between the blower and the point to which the air is to be finally exhausted, preferably the fallen roof area or gob. A collector of the cyclone type is depicted. In coal mines, a salable dust may be recovered, and the possibility of dust explosions minimized. In other types of mines the dust often has value, and the dust nuisance is further reduced.

Referring now to a modification of the present invention, as illustrated in FIG. 1, which constitutes a preferred embodiment for use in longwall mining systems: numeral 1 represents the mining machine, in this case a shearer-loader with ranging cutting drum. The longwall, not shown, is in the foreground. Face conveyor 2 removes the material mined by the rotating cutting drum (picks on the drum not shown). Spill plate 3 prevents mined material from tumbling into the roof support area just on the far side of the spill plate. The passageway 4 carrying electric power cables for the longwall mining system is shown as below conduit 5. Supports 7 are fabricated to permit the bottom portion of flaps 8 to swing inwardly, and also to allow the unobstructed passage of activating shoe 9, attached to machine 1, in its passage back and forth before the longwall. In the embodiment shown, support 7 is also fabricated to supply a groove or half-bearing surface 11 for the flaps, and the bearing is sufficiently wide to accommodate the rotating pivot surface of both adjacent flaps. As will be shown in FIG.- 3, this bearing surface may be divided to insure a wellcentered, free swinging flap. The trough or channel inthe spill plate for taking up the electric power cable and water hose is shown as I2.

lf trouble is encountered with large pieces of mined material entering the conduit through flaps designed to open outwardly, this can be prevented by protecting the area with a shield such as 13, connected to the mining machine along its length, just over the open ports. Pieces caught by the shield drop through openings 14 to the conveyor. Alternately, a shield may be connected to the conduit as illustrated in FIG. 4.

Referring to FIG. 2, the flaps are hinged at the bottom edge, so they may be pressed inwardly by members such as 9, 15 or 16 extending from, or activated by, the mining machine. Many variations of this extending member are applicable. Three are shown. A shoe 9 is illustrated, which may be a sliding member, or it may have on its contact surface, roller bearings 17 or wheels, rollers, balls or the like. An extending member 15 consisting of a roller or wheel could be used. Another modification 16 is a wheel or roller, having sufficient bias to overcome the bias of the flap, yet able to pass over any irregularities it might encounter.

There are many ways in which the flap may be I hinged. The method shown permits easy removal by unfastening strip 18, and tilting the plate. Various types of springs may be used to supply bias to overcome the air pressure on the plate due to the lesser pressure within. Coil springs 19 are shown, although single leaf springs are quite adequate. The flaps are shown as stopped in their rotation by strip 21, although lugs or pins could serve as well.

H6. 3 depicts flaps which have swivel surfaces 22 above the midpoint of the flap, so that when these flaps are suspended from bearing surfaces 11 in supports 7, they hang in a normally closed position, thus blocking the flow of air into the conduit. The force of gravity therefore provides the necessary bias.

Although spindles could be used, extending from the plates as pivots, fabricating the flaps as shown can achieve the same effect in a simple manner; The notches 24 are of such size as to clear the extending hook 25, and to fit snugly about it when in the normally closed position. These flaps are opened by pressure on the upper portion by an extending member from the mining machine. Supports 7, which support both the channel 12 and the flaps are fabricated with slant sections 26, so as to permit the upper surface to swing back a limited amount within conduit 5.

As a preferrred embodiment, the floor of the conduit 28 of cross section 27 slants slightly downward toward the bottom edge of flap 8. This serves a double purpose, for any dust of particles which settle out at the floor 28 will tend to accumulate along the edge of the closed flap and when the flap is first partially opened, the inward rush of air will cause much of this material to again become airborne. Furthermore, it will simplify cleaning, for if the flaps are lifted off their hooks, the conduit can easily be hosed free of any accumulations. Alternately, such flushing can be accomplished generally without even removing the flaps, by admitting water through pipeline 29, having multiple perforations or nozzles 31.

As shown, two adjacent flaps 8 hang from one support 7. These flaps will swing with no danger of interference, if the bearing surfaces are divided in some manner to insure that the flaps remain precisely centered. Such division may be achieved in many different ways, as by tabs, pins, or raised portions. In this figure a separating surface 32 is shown.

It may be desired to maintain an inflow of dust ladened air throughout the length of the conduit, in addition to a more massive or voluminous flow at the point where the machine is mining. This inflow through the length of the conduit may be achieved by openings in the flaps, or in the conduit wall, here represented as perforations 33 in the flaps.

FIG. 4 depicts flaps which have swivel surfaces 22 i below the midpoint of the flap, so that when they are suspended from bearing surfaces 11 in supports 7, they require bias or other means to maintain themselves in a normally closed position, particularly when the system is shut down and a pressure differential does not exist to maintain them in this position. A latch 23 is shown. which will maintain flaps in their normally closed position once they are closed by an extending member attached to, or activated by, the mining machine. Such a latch will keep the flap in closed position even during periods of shut down, but it will readily unlatch when a superior force is applied to the section of the flap below the pivots by a member extending from or activated by the mining machine.

A flap of the type shown as 41 can be maintained in its normally closed position by spring bias, but one of type 34 will gravitate to its normally closed position in consequence of weight 35 which maintains the center of gravity on the conduit side of the axis even when it is in the open position. When the flap is opened by pressure on the portion below the axis, air enters the conduit through opening 36. Edges 37 are rounded so as to substantially effectuate a uniform radius from the axis to the lower edge, and prevent binding against the floor of conduit 38.

Shield or grate 39 which extends the length of that portion of the conduit which is parallel to the path of operation ofthe mining machine, is designed to prevent pieces of mined material inadvertently falling into the conduit through those flaps which otherwise provide such access when in their open position. Alternately, a shield serving the same purpose may be attached to the mining machine itself, as shown in FIG. 1. This arrangement is preferable, as a shorter length is obviously required. Either type of shield may divert such pieces of mined material to the face conveyor.

FIG. illustrates another variation wherein the flaps are designed to gravitate from the open to the closed position. Pivot shafts 41, which may if desired consist of a continuous rod across the front of the flap, are placed sufficiently distant from the flap on the side away from the conduit, to displace the center of gravity to the conduit side of the axis, even when the flap is in the open position. Thus, if unimpeded, the flap will gravitate to the normally closed position.

FIG. 6, numeral 42 represents a cross section of the conduit of FIG. 5 taken through line 6-6 with the flap in the closed position, whereas 43 represents the same, with the flap in the open position. Pivoting shaft 41 is sufficiently far to the right, so that even with the flap in the position of drawing 43, the center of gravity is to the left of the axis, and the unimpeded flap rotates to the closed position 42. Extending member 15, attached to or activated by the mining machine, is shown in the act of pressing flap 8 in drawing 43 into the open position. Shoe 44 represents one of many types of devices which, attached to or activated by the mining machine, would urge an open flap into its closed position. This may be a sliding shoe, or it may include rollers, wheels, balls or the like. Roller bearings along the contact surface of a shoe. as shown at 45 are satisfactory.

Referrring now to FIG. 7, the conduit is shown with the intake of an air moving device, such as a motor driven centrifugal blower 40 connected to one or both ends ofthe conduit. The blowers are connected by flexible conduit 46. This not only serves to minimize the amount of vibration, which is transmitted from the blower assembly to the conduit, but also permits the placement of the blowers at any point desired, with respect to the conduit.

If a blower is connected to each end of the conduit, it is preferable to divide the conduit into two separate conduits by a partition (not shown) or by other suitable means.

The air exhausted by the blowers is preferably conducted into the fallen roof area or gob."

With reference to FIG. 8, the situation is the same as that of FIG. 7, except that a dust collector has been interposed between the exhaust from the blower or blowers, and the fallen roof area. A cyclone dust collector 47 is shown, having an air lock gate 48 such as a star valve, so that the collected solids may be removed at 49. Frequently the dust collected has economic value. In any case its removal further reduces the dust level of the area, and in the case of a combustible dust such as coal dust, minimizes the possibility of a dust explosion.

EXAMPLE OF THE PREFERRED EMBODIMENT A spill plate assembly is constructed, adapted for use with an Eickhoff Shearer-loader, which has a topside trough with steel plate floor for receiving and playing out water hose and electric power cable to the shearerloader as it moves back and forth across the longwall being mined. At the bottom section of the spill plate assembly, a passageway is provided for power cables required for the longwall mining system. Between the two there is a conduit extending the full length of the spill plate which in this instance is 500 feet in length. There is, however, a removable partition at about the midpoint of the conduit, thus dividing it into two sections, open for connection at either end. The distance between the roof and floor of this conduit is 20 inches and the distance between its side walls, 10 inches. The side of the conduit toward the conveyor consists of a series of rectangular ports, the side of each being defined by a support of special design, 1 inch thick and 20 inches high which serves to support the' top of the trough toward the conveyor, and to provide pivot points for the flaps. These supports are spaced at 15 inches intervals by centers, and are similar in appearance to those of the accompanying drawing FIG. 3.

The supports are fabricated from abrasion resistant steel containing about 2 percent manganese, (U.S. Steels USS-TI), and stand upright in the conduit. Their lower cross section is rectangular, being 1 inch wide and 1% inches deep. A front I inch edge coincides with the edge of the floor of the conduit facing the conveyor. This rectangular section of the support extends perpendicularly upward from the floor of the conduit for 14 inches, at which point a substantially constructed hook extends outwardly from the conduit for a distance of 1%. The inner curve of the hook has a radius of 9/32 inch, and at its lowest point is 15 inches above the floor of the conduit. The axis of this semicylindrical curve is in a line parallel to the lower edge of the conduit, but overhangs it in the direction of the conveyor by one-quarter inch.

The portion of the support retains its rectangular cross section above the hook, but slants backward, tangentially from the surface of the curve of the hook by 30 from the perpendicular. This is to allow the upper portion of the flap, pivoting from the hook, to swing inwardly unobstructed. It is also to allow the activating projecting member attached to the mining machine to move in its path, unobstructed by the supports. The upper surface of the support, 20 inches from the lower surface and parallel to it, is securely attached to the undersurface of the trough, thereby providing support. The semi-cylindrical inner surface of the hook, which is to provide a bearing surface for two adjacent freeswin'ging plates or flaps, is divided into two equal portions by a thin partial partition, being an integral part of the hook, and at right angles to the axis of the semicylinder. Thus, one side of one flap may pivot in one portion, and the adjacent, in the other.

The forward under-surface of the trough is fabricated to overhang the forward edge of the floor of the conduit, in a vertical plane, by one-half inch.

The flaps are constructed of one-half inch USS-Tl abrasion resistant steel plate. They are 14 15/16 by inches, and along their longer edges, they have notches, one-half inch deep and just long enough to slip over the hook and allow the flap to swing freely. In this instance they were 1% inch long. The notches start 4 15/16 inch from the upper edge of the flap, and both the upper edge of the 'flap, and the upper horizontal surface of the notch, are rounded to a radius of onequarter inch, the latter to provide a bearing surface for cooperation with the curved inner surface of the hook. Each flap is now hung between the bearing surfaces of two supports, providing a closed conduit having inside cross sectional dimension of 10 20 inches. If pressure is applied to t he upper section of the plate, it will swing in at the top, and out at the bottom, but if pressure is applied to the bottom, it has no effect, as the lower edge of the plate'extends half an inch below the floor of the conduit. The flaps gravitate to a normally closed position.

These flaps have perforations to provide a certain degree of suction throughout the length of the conduit. Two centrifugal blowers, manufactured by the Joy Manufacturing Co. of Pittsburgh, Pa. are connected to the partitioned conduit, one at each end. To achieve further sound abatement and flexibility of movement, each blower is positioned 50 feet from the spill plate, and connected to its rigid conduit, by flexible 24 inch conduit. The blowers are rated at 8,000 cubic feet per minute with a negative pressure of 20 inches of water. Although not necessary to the proper functioning of this invention, it is preferable to progressively reduce the internal dimension of the conduit as the distance to the intake of the blowers increases, according to conventional engineering principles, in order to maintain sufficient air velocity throughout, to prevent appreciable fall-out of suspended dust particles. Such reduction in its internal dimension can readily be accomplished by installing a partition extending inwardly from the wall of the conduit opposite the flaps.

An extending shoe along the spill plate side of the shearer-loader, having roller bearings along its contact surface is positioned to open the flaps by pressure on their upper surfaces. Pressure is applied three feet before the mining machine reaches a flap. lt maintains all the flaps in the open position which are adjacent to it, and permits the flaps to close slowly (because ofa grad ually sloping shoe), three feet after it has passed. The dust ladened air is sucked from the area into the adjacent conduit, and is directed by the blowers to the fallen roof area, being conveyed thereto by 24 inch flexible conduit.

While 1 have described a preferred embodiment of my invention, it will be understood that various modifications and changes can be made in the dust removal system described, without departing from the spirit of this invention or the scope of the following claims.

I claim:

1. An apparatus for removing dust ladened air from the vicinity of a movable machine irrespective of the location of the machine within its field of locomotion, and conveying the dust ladened air to a selected area distant from the machine, comprising:

a rigid conduit positioned adjacent to the path of operation of the machine; means for maintaining the conduit at a pressure lower than the pressure of the surrounding air; a series of normally closed ports along the conduit; means for opening ports adjacent to the machine, and for closing said ports when they are nolonger adjacent to the machine because of its continuing travel; and at least one device for moving large volumes of air entering the conduit and discharging the air to a preselected area.

2. The apparatus of claim 1 wherein the movable ma chine includes means 'for opening the ports.

3. The apparatus of claim 1 wherein the movable machine includes means for closing the ports.

4. The apparatus of claim 1 wherein the preselected area for discharge of the dust ladened air is the fallen roof area of a mine, with a conduit employed to conduct this air from the device for moving large volumes of air to the fallen roof area.

5. The apparatus of claim 1 wherein the conduit assembly is adapted for use in the mining of minerals by longwall type methods, the machine being a device such as a shearer-loader, plow, or mining machine, and the conduit comprising a passageway built into the spill plate section which lies between the machine and the roof support area.

6. The apparatus of claim 1 wherein a dust collector is in communication with the exhaust ports of the at least one device for moving large volumes of air entering the conduit.

7. The apparatus of claim 6 wherein conduit conducts exhaust air from the dust collector to the gob.

8. The apparatus of claim 1 wherein at least one device for moving large volumes of air is positioned with its intake opening in substantially air tight connection with one end of the conduit.

9. The apparatus of claim-8 wherein the conduit is in the form of two substantially independent sections, the pressure of each section being maintained by a blower attached to the end of that section.

10. The apparatus of claim 8 wherein the intake of the device is attached to the rigid conduit by flexible conduit to allow flexibility in the positioning of the blower, and minimize vibration transmitted from the device to the conduit. i

11. The apparatus of claim 1 wherein the conduit has a face toward the machine,'a series of flaps on the face, each being rotatably arranged for limited motion about an axis, from a position where it substantially blocks the influx of air through a corresponding port, and a second position wherein it admits a flow of air into the conduit through the port.

12. The apparatus of claim 11 wherein the flaps are biased into a normally closed position.

13. The apparatus of claim 11 wherein the flap is constructed so that the center of gravity is at all times in a position with respect to the axis, to induce rotation of the flap to the closed position.

14. The apparatus of claim 1 1 wherein the flaps pivot in grooved brackets for easy assembly and removal.

15. The apparatus of claim 11 wherein the movable machine has an extending member to open the flaps in passing, by pressing inwardly, a portion of the pivoted flap in superior opposition to the biasing force, and when the extending member moves beyond the flap because of the movement of the machine to which it is attached, the unopposed biasing force closes the flap.

16. The apparatus of claim 11 wherein an extension from the movable machine closes the flaps which have previously been opened.

17. The apparatus of claim ll wherein the flap includes a latch which cooperates with a member extending from the conduit, said latch being spring biased to hold the flap in the closed position until said latch is forced open by a superior force. 18. The apparatus of claim 11 wherein the floor of the conduit slopes downwardly toward the bottom edge of the flaps, to aid in keeping the conduit free of deposit, and to aid in cleaning the conduit.

19. The apparatus of claim 11 wherein a perforate or slotted pipe extends within the conduit for the conduction of water to points along said conduit, for flushing it free of possible accumulations of dust.

20. The apparatus of claim 11 wherein the flaps are foraminous whereby a flow of dust ladened air into the conduit will occur at all times the apparatus is in operation, substantially throughout the length of the conduit.

21. A method of removing dust ladened air from the vicinity ofa movable machine and a conduit associated with said machine and conveying the air to a selected area distant from the machine, comprising: maintaining a zoneof air pressure lower than that of the surrounding air, fixedly positioned relative to, and adjacent to, the path of operation of the machine, admitting dust ladened air into the zone of lower pressure from the vicinity of the machine and points along the conduit, irrespective of the location of the machine within its field of locomotion, and discharging the air from the zone to the selected area; wherein the movable machine activates the opening and closing of ports in said conduit in the zone along its path of travel.

22. The method ofclaim 21 wherein the dust ladened air within the zone is discharged into a fallen roof area.

23. The method of claim 21 wherein the zone is in the form of two substantially independent sections, the pressure of each being maintained by a blower connected to the end of that section.

24. The method of claim 21 wherein water is forced into the zone to facilitate removal of dust therefrom.

25. An apparatus for removing clust ladened air from the vicinity ofa moving machine irrespective of the location of the machine within its field of locomotion and conveying the dust ladened air to a selected area distant from the machine, comprising: a rigid conduit positioned adjacent to the path of operation of the machine, said conduit having perforations along its length for admitting dust ladened air at points along the conduit; means for maintaining the conduit at a pressure lower than the pressure of the surrounding air; and at least one device for moving large volumes of air entering the conduit and discharging the air to a preselected area.

Claims

1. An apparatus for removing dust ladened air from the vicinity of a movable machine irrespective of the location of the machine within its field of locomotion, and conveying the dust ladened air to a selected area distant from the machine, comprising: a rigid conduit positioned adjacent to the path of operation of the machine; means for maintaining the conduit at a pressure lower than the pressure of the surrounding air; a series of normally closed ports along the conduit; means for opening ports adjacent to the machine, and for closing said ports when they are no longer adjacent to the machine because of its continuing travel; and at least one device for moving large volumes of air entering the conduit and discharging the air to a preselected area.

2. The apparatus of claim 1 wherein the movable machine includes means for opening the ports.

9. The apparatus of claim 8 wherein the conduit is in the form of two substantially independent sections, the pressure of each section being maintained by a blower attached to the end of that section.

10. The apparatus of claim 8 wherein the intake of the device is attached to the rigid conduit by flexible conduit to allow flexibility in the positioning of the blower, and minimize vibration transmitted from the device to the conduit.

11. The apparatus of claim 1 wherein the conduit has a face toward the machine, a series of flaps on the face, each being rotatably arranged for limited motion about an axis, from a position where it substantially blocks the influx of air through a corresponding port, and a second position wherein it admits a flow of air into the conduit through the port.

14. The apparatus of claim 11 wherein the flaps pivot in grooved brackets for easy assembly and removal.

17. The apparatus of claim 11 wherein the flap includes a latch which cooperates with a member extending from the conduit, said latch being spring biased to hold the flap in the closed position until said latch is forced open by a superior force.

18. The apparatus of claim 11 wherein the floor of the conduit slopes downwardly toward the bottom edge of the flaps, to aid in keeping the conduit free of deposit, and to aid in cleaning the conduit.

21. A method of removing dust ladened air from the vicinity of a movable machine and a conduit associated with said machine and conveying the air to a selected area distant from the machine, comprising: maintaining a zone of air pressure lower than that of the surrounding air, fixedly positioned relative to, and adjacent to, the path of operation of the machine, admitting dust ladened air into the zone of lower pressure from the vicinity of the machine and points along the conduit, irrespective of the location of the machine within its field of locomotion, and discharging the air from the zone to the selected area; wherein the movable machine activates the opening and closing of ports in said conduit in the zone along its path of travel.

22. The method of claim 21 wherein the dust ladened air within the zone is discharged into a fallen roof area.

25. An apparatus for removing dust ladened air from the vicinity of a moving machine irrespective of the location of the machine within its field of locomotion and conveying the dust ladened air to a selected area distant from the machine, comprising: a rigid conduit positioned adjacent to the path of operation of the machine, said conduit having perforations along its length for admitting dust ladened air at points along the conduit; means for maintaining the conduit at a pressure lower than the pressure of the surrounding air; and at least one device for moving large volumes of air entering the conduit and discharging the air to a preselected area.