US 2990166 A
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Description (OCR text may contain errors)
M. A. WALSH MINING METHOD June 27, 1961 Filed Aug. 29, 1957 3 Sheets-Sheet 1 INVENTOR MVLES A. WALSH BY @.MM
ATTORNEYS 3 Sheets-'Sheet 2 M. A. WALSH MINING METHOD Wg m )5A MVLES A. WALSH Jg my M BY ATToRNEYs June 27, 1961 Filed Aug. 29, 1957 M. A. WALSH MINING METHOD June 27, 1961 3 Sheets-Sheet 5 Filed Aug. 29, 1957 ooooa MINE PRDPS Pmon. AFL-r PILLAR.
mi?? INVENTOR Mmes A. WALSH ATTORNEYS United States arent 2,990,166 MINING METHOD Myles A. Walsh, 6515 Boulevard E., West New York, NJ. Filed Aug. 29, 1957, Ser. No. 681,022 4"Claims. (CI. 262-1) This invention relates to an improvement in mining practice and is more particularly concerned with the provision of a novel method of providing support for the walls of underground working areas during the course of the mining operation or in the development of the mine preparatory to removal of ore. The invention also has utility in providing support for the walls of underground openings produced for other purposes than for the extraction of minerals, as for example in various tunneling operations, and for supporting the sides of ditches, trenches and other excavations.
The invention will be described with particular reference to its application in underground mining where support of the roof, arch or beam section of the overlying rock burden, while the ore body is being mined out, has -been and remains a serious problem entailing increasing mining costs because of increasing scarcity and cost of timber for mine props and similar supports. More recently, resort has been had with considerable success to roof rbolting but this likewise entails a very considerable expense in the form of labor and materials, and, moreover, this method does not insure against heaving or rising of the oor.
The present invention has for one of its important objects to reduce and in some cases to eliminate entirely the necessity for using props and similar supports during the period when the working areas of the excavation must be safely accessible.
It is a further object of the invention to bring about marked savings in labor and material costs, since the supporting means of the present invention may be used over and over again and may be installed, removed and transferred to a new location with much` less labor requirement than is needed with the methods previously in use.
It is -a still further object of the invention to bring about increased safety for the miners and other workmen engaged in mining or other underground operations or in excavations that are not underground in nature.
The invention has for a further object or advantage the recovery of a higher percentage of the ore body thanV is usually now recoverable with the use of timbering and other existing methods of support.
Other objects and advantages will be brought out as the description proceeds.
The invention in its broader aspects is concerned with the provision of supports for the walls of the working area through the medium of inflated exible containers iilled with a suitable iiuid and bearing over extended areas of their surfaces against the walls o-f the working area which are to be supported. The degree of support required for the particular operation may be ensured by using inflatable containers of suitable sizes and shapes and filling them with a compressible fluid such as air under a suflicient degree of compression to provide adequate support. When the containers are appropriately designed so that when in use they will present extended areas of supporting surface in bearing relation to the roof, oor or other wall area to be supported or maintained against movement, it will usually be found that the degree of compression of the contained fluid may be kept relatively low. In` many cases when using compressed air as the inflating fluid for the containers only a relatively low degree of compression, say 2 to 3 lbs. p.s.i.,` will be found adequate to provide support for the fractured ground and keystone ofthe roof section of the stope or other area being mined. Higher pressures may be employed if required, and since in mining operations compressed air is readily available within a wide range of pressures, it represents a cheap and easily available fluid for the purpose. However, other lluids, including water and other liquids or mixtures of `a liquid and a compressible uid, may be used if conditions make it more desirable to employ such an inflating medium than compressed air or another gaseous fluid.
When a particular area has been mined out or excavated and it is desired to shift the support closer to the working face, it is a simple matter to partially d'- flate the container or containers suiiiciently to disengage them from the wall or roof area being supported, then move them forward to the new location and reinilate them to the desired degree. By providing suitable connections to the container for facilitating partial discharge of the contents from a distance and also similarly providing appropriate hand lines or other means for moving the container closer to the Working face, such manipulations of the container may be made without imperiling the workmen because of any tendency for the roof to cave when the support is withdrawn.
The inflatable containers may take various forms and shapes. For most underground mining operations they should be made of a suitable elastomer of `adequate thickness and strength for the particular type of operation. Various types of natural and synthetic rubber materials are 'available and may be used in `forming the containers, especially when they are intended to be used over and over again. As will be mentioned further hereinafter, in some applications the container may be left in place and not reused. For example, Where the container in its inflated condition is in bearing relation to wall surfaces being supported on all sides of the conrainer or at least over the major portion of its surfaces and its continued presence in the excavated area will not interfere with the purposes for which the excavation has been made, then it may be made of relatively thin and inexpensive material. `In such circumstances various of the synthetic polymers such as polyethylene that are available in thin sheetl form may be used.
The invention will be more particularly described by reference to the accompanying drawings and its appliction in connection with several typical underground mining operations:
In the drawings:
FIG. 1 is a side elevation of one form of inflatable container that may be used in the practice of the invention and which is sho-wn in inated position in supporting relation to the back or roof of an excavation which may correspond to a mined out section of a coal seam or similarly shaped mineral deposit with the container resting on the floor;
FIG. 2 is a cross-section taken on the line '2-2 of FIG. l showing the inflated container in the flattened position it will normally assume when in supporting relation to the roof;
FIG. 3 is a perspective view of another form of inflatable container that may be used in the practice of the invention;
FIG. 4 is a part side elevation and part section of the inflatable container of FIG. 3 shown in inflated position in supporting relation to the back or roof of an excavation;
FIG. 5 is a schematic plan View showing the application of the invention in a long wall mechanical mining operation;
FIG. i6 is a vertical section through an ore body typical of certain copper and .molybdenum ores that has been caving method;
FIG. 7 is an isometric part horizontal section and part plan view taken on the line 7 7 of FIG. 6 which passes horizontally through a series Vof undercuts as they are usually formed in the undercut block-caving method;
FIG. 8 is a schematic plan view showing an application 'of the invention using inflatable containers of the type lillustrated in FIG.y l in maintaining temporary pillar support in an operation directed to the removal of pillars following a typical room and pillar mining operation;
FIG. 9 is a schematic plan Viewl similar to FIG. 8 as respects the basic mine layout but representing the prior art procedure when using props for support of the roof 'during the removal of the pillars; and
FIG. l is a part vertical section and part side elevation illustrating still another application of the invention, in this case showing use of an inated container in conjunction with timber support to sustain a roof section of an excavation which may be a tunnel or a mined out section of a mine.
As shown in greater detail in FIG. 1 and more generally in FIG. 5, the inatable containers used in practicing the invention may take the form of elongated cylinders 10 provided with trunnion-like members `12, at Ithe opposite ends, or if desired these members may be in the form of a shaft extending lengthwise through the cylinder and protruding at each end to provide means for attachment of hooks connected to cables or poles by which vthe cylinders may be rolled from one position to another. A pipe connection 13 is provided for filling the container with a suitable fluid and emptying same when deating same. In order to facilitate handling of the containers and provide support for the members I12 at the ends of the cylinder, metal collars 14 may be secured at the ends of the cylinders with the members 12 secured thereto or mounted in bearings formed in the collars 14.
FIGS. 3 and 4 show a modified form of inflatable container. In this case the container takes the form of a shallow cylindrical tank 16 generally at on the top and bottom and provided with a reinforcing band of any suitable material, for example, a woven wire band 18, which is of considerably narrower width than the height of the container when it is iniiated to normal operating size. In order to facilitate movement of the container from one site to another by sliding along a floor area and also to protect the bottom against undue wear and abrasion, skids 20 may be secured to the outside of the bottom surface.
Referring more particularly to FIG. 5, 21 represents the face of an ore body, for example, a coal seam or a potash deposit, which is being mined mechanically by the long wall method. A series of iniiated containers 10 are shown as disposed along the section a of the face of the ore body in a position sufficiently spaced from the face to permit the movement of the mining machine back to its starting position after having completed the mining of a given width section, block or cut of the ore body. The mining machine, not shown, advances parallel to the face in the direction indicated by the arrow. In this type of operation ordinarily a mechanical conveyor, not shown, will be associated with the mining machine to the rear or at the side thereof to receive the mined ore and transfer it to a haulageway not shown.
As shown opposite section b of the face of the ore body, two of the intiated containers have been partially deated, moved inwardly toward the face of the seam from their previous positions, shown in dotted lines, and reiniiated to provide the necessary support for the roof as the fresh cut is taken from the ore body. The iniiated containers also serve to retard any tendency for the bottom wall or oor to rise or heave. As each container is moved closer to the face of the ore body the roof is left without support to the rear thereof and is permitted to cave in the customary manner. As shown at Z3 waste rock, or gob, and refuse that might have been required to be re- 4 moved in the course of the operation is disposed in the spaces between the ends of adjacent alined inflated containers and left in the space to be caved as in the older practice when using props or roof bolting.
The inflated containers'of FIG. l are of suitable diameter or height when inflated to the requisite degree to provide the proper support for the roof area and to span the height of the excavation or thickness of the coal seam `and present extended areas of bearing contact with the roof and floor. At the same time when partially deflated they will be freed from contact with the roof area and then may be rolled or skidded forward to a new position at the working face by pulling on the trunnion or shaft members. They are then reintiated to the desired degree.
When the modified type of container of FIG. 3 is used a similar procedure may be followed as regards partial deflation and reinflation in moving the containers to the new location except that in this case the containers are slid along the lioor surface to the new location. The use of the shallow type tank of inflatable container may be preferred when it is desired to ensure a wider area of bearing contact with the roof to be supported, as, for example, when working under conditions which would otherwise require leaving portions of the ore body in the form of pillars to keep the overlying rock from caving before the mining operation has been completed. In other words, containers of this type may be regarded as temporary pillars, but if circumstances dictate they may be left permanently in place. When they are not intended to be recovered and reused they may be made of a relatively thin material thus lessening their cost.
FIGS. 6 and 7 illustrate another useful application of the inflated container principle, in this case in connection with the undercut block caving method of mining. In preparing a given portion of an ore body for block caving it is customary to develop a series of undercuts at suitably spaced intervals along the bottom of the ore body that is to be caved, these undercuts being in registering relation to finger raises that are often driven through vthe foot wall or underlying rock formation, and which in turn connect with the main raises leading to the haulage level below.
Since ores that are susceptible of block caving are frequently relatively easily broken up and may have a tendency to loosen and come down into the undercuts while they are being prepared and thus prematurely with respect to the blasting that is usually done on completion of the preparation of the ore body for the caving and drawing, it is often necessary to provide timbering in the undercut areas as they are being formed. This is not only expensive but also has the disadvantage that the timbering has to be removed when the preparation has been completed in other respects; otherwise the props or other timbering would tend to hinder the free ow downwardly of the ore loosened by the blasting and may even plug up the passages. Moreover, the removal of such customary timb ering in advance of the blasting represents a very serious hazard to the workmen involved.
The present invention affords a very simple means for overcoming the drawbacks of the prior practice mentioned above. As the undercuts and stub drifts therefrom into the ore body are formed and as individual seetions are completed, the spaces may be filled by suitably shaped inflated containers bearing on all sides, or over most of their surface areas, against the exposed surfaces of the ore body land retain same in place. Inated containers used for this purpose may be made of relatively thin materials such as polyethylene. When the ore body section that is to be caved has been fully prepared for caving, the containers may and usually will be deflated. Suitable hose connections will preferably be provided to permit of the deflation of the containers by manipulations performed from a point outside the undercuts, thus avoiding the necessity for a workman to expose himself to danger. In their deflated state, the containers will have little, if'any, tendencyrto` hinder the free flow downwardly of the loosened ore and will pass along therewith inthe drawing of-the oreif they cannot be retrieved upon deflation and prior to the blasting step. Moreover, the simultaneous deflation of the containers by remote controll can induce controlled caving.
As shown more particularly in FIGS. 6 and 7, 25 indicates generally an ore body that has been prepared for the caving operation with the customary raises 264 the undercuts 29, the cross undercuts 30 and the stub drifts 31 are supported by inflated containers 32a, 32b, 32C, 32d, 32e, etc. suitable degree so that their wall surfaces are in pressing relation to the wall surfaces that are to be supported. It
Will be understood that the containers 32a, 32b, etc. will be placed individually as the Work of forming the undercuts and their associated stub `drifts progresses from one end or side of the ore body to the other so that in the interval between the initial excavation of the undercuts and drifts at the one end, or side, of the ore body being prepared for caving, until the undercuts and drifts are completed at the other, there will beno opporunity for the ore exposed at the surfaces of these excavations to loosen up and slough down or start premature caving.
As the containers 32a, 32b, 32C, 32d, etc. are progressively installed, they will press one against the other and` thus support each other wherever they `do not come in contact With rock or ore body surface or temporary timbersupport. Although not shown in FIG. 7 it will be understood that the containers 32a, 32b and 32o are supported at their rearward sides as viewed in the drawing by the Wall surface 29 of the rearmost undercut 29 (the one-at the leftend of the series shown in FIG. 6) in the oreblock that is being prepared for caving. It is to befurther understood that the containers will be installed and inflated progressively as the undercutting proceeds and that they are shown as omitted from the undercuts 29 and 30 in the forward parts ofthe block only so as-not to complicate the illustration of the undercutting of 'the ore block involved. During the period of installation each container 32a, etc. will be inflated to whatever pressure is necessary for its safe installation throughv hoses leading from raises 28. The ination pressure will be progressively increased for each container 32a, etc. so that a container last installed, and thereby temporarily unsupported at one end, will be subjected to only a relatively small ination pressure. Where necessary combinations of the forms of support shown in FIGS. l, 4 and 10 may be used during the progressive installation of containers.
For example, and depending on the particular characteristics of the ore body, the containers 32a, 32b and 32C can initially be iniated to a relatively low pressure, say lbs. p.s.i. A similar low pressure ination may be produced initially in the containers 32e installed in the stub drifts 31 and the containers 32d installed in the cross undercuts 30. When the containers 32a' have been installed in appropriate relation to the adjacent surfaces of the previously installed containers 32a, 32b, 32C and 32e, and assuming that similar support has been provided for the exposed end surfaces 33 at the opposite ends of the aligned roW of containers 32a, 32b and 32C, either by inated containers or temporary timber support, then the pressure in the containers 32a, 32b, 32e and 32e may be increased, say to l0 lbs. p.s.i. This procedure may be repeated as each row of undercuts, stub drifts and the associated cross undercuts is lled until the preparation of the block is completed.
These containers are inated to a- If desired, as for example, when the ore is susceptible; to induced caving merely by a markedreductionfof the.
pressureapplied by means of the containers, or by pulsations ofY the pressure, the pressures inthe containersdisposed throughout the block or a selected section thereof` may be still further increased to any desired degree, or
alternately increased or decreased, and in this way induce;
controlledcaving without resort to explosives.
FIG. 8 illustrates an application of the invention inv mined out in sections according to a definite sequential arrangement so as to enable the most economical use ofl the available labor and also to make more practical use of conveyors to transport the ore to a haulageway. As shown the ore is placed in the angularly arranged branch conveyors 35y and transported to the conveyors 36. and along themA in turn to a suitable conveyor 37, and thence tothe main conveyor 38 located in the cross entry 39'. This conveyor transports the yore to a haulageway not shown. The letters A, B, C and D applied to FIGS. 8 and'9 designate smaller sections ofthe pillar and their'order of. removal, those marked A being first removed, then thosey The number of sectionsf.
marked B being removed, etc. that will be mined simultaneously will, of course, depend on local conditions, and in this respect the arrangement' shownin the drawing is to be regarded as presented merely by way of example.
In FIG. 8 the mine props are omitted' entirely and instead a series of inilated containers 10 is shown extending acrossthe space to the rear of the working areas atthe pillars as well as across the space between the pillars-'andi the spaces to the sides thereof representing the previously mined out-entries. As will be seen further in FIG. 8,
certain of the containersl are more advanced toward" the pillars and in the space therebetween than" the others inordertocorrespond with the greater extent of progress inthe removal of the pillars. The. containers 10V as shown are of the type illustrated in FIGS. 1 and 2. It will be understood, however, that they may be of the type shown in FIGS. 3 and 4 or of any other suitable shape.
FIG. 9 shows the same arrangement as in FIG. 8 except that instead of the inflated containers 10 mine props are used for roof support.
FIG. 10 shows still another application of the invention wherein the inflated containers of the invention are used in conjunction with timber support of a kind that is frequently required when tunneling or in mining certain types of ore bodies. As shown, the surface of the excavated space is of irregular shape in cross-section and the roof does not lend itself to support by conventional mine props because of the extent of the span between the roof and the oor and also its irregularity presents complications. In dealing with such special situations in the past, it has been customary to build up a timber cribbing 40 which may be covered with timber lagging 41 to furnish support for the workmen and equipment required when mining out the upper portion of the ore body, but resort then has been had to timbering arranged in various supporting relations to the roof 42, depending upon the shape and the cross-section thereof. In the drawing 43 represents a portion of the space that was originally occupied by the ore body or rock excavated in a tunneling operation and which extended above the level of the timber lagging. It is assumed that the mining out or excavation of the rest of this extended portion of the rock or ore body is progressing along the extent of the timber crib- As. shown in both of FIGS. 8 and 9, the pillars are being bng and lagging support area generally at right angles to the section shown in the drawing.
container 45 has been installed in the excavated area at a suitable distance from the remaining portion of the rock or ore body that is in the process of removal. The container 4S may initially be of balloon shape and, when inflated to the pressure required to bring about suitable support, will accomodate its surface areas to the irregularities of the surfaces of the excavation on the one side while resting on the timber lagging on the other. Here again, as in the previous examples, the inflated container or containers may be partially deflated and moved progressively toward the working area as the excavation of the rock or ore progresses. Alternatively, the container or containers may be left in place to support the back or individual keystone units of the back or roof section for the period that the tunnel or excavation needs to` be maintained without caving. When they are made of rela. tively inexpensive material, the economics of the particular tunneling or mining operation or other considerations may make it desirable to leave the inated container in place indefinitely.
The several examples described above are set forth merely by way of typical illustration, and it will be under-V stood that the invention is not limited thereby. The containers and the application thereof may take many forms depending upon the particular conditions presented. As indicated generally earlier herein the invention also may be used in shoring up the sides of ditches, trenches and other open excavations pending; relling or installation of permanent walls or supports. This may be done by a container used in conjunction with temporary timber support as in FIG. 10, or may be accomplished by containers such as those of FIGS. 1 and 4, or other shapes as required by lthe walls of the open excavation. It will be understood that the invention is not to be deemed as limited otherwise than as indicated by the appended claims.
`1. The improvement in underground mining which comprises inducing subsidence of an arch or beam segment of the roof section of an excavated area by disposing an inflated exible container in temporary supporting relation to an extended portion of the open face of Vsaid segment and thereafter pulsating the pressure,`
exerted by said container on said segment by adding fluid to and withdrawing iiuid from said container by means actuated from a point remotely situated with respect l to the segment intended to be subsided.
2. The improvement in the undercut block-caving method of underground mining of large masses of friable ores and similar materials which comprises introducing inflatable containers in the undercut openings progressively as they are formed, iniiating said containers with a uid so -they bear in temporary supporting relation against the wall surfaces of said undercut openings, and, subsequently pulsating said containers by alternately increasing and decreasing the fluid pressures therein toinduce caving throughout the mass that is to be caved.
3. The improved method of inducing caving according to claim 2, 'wherein a series of said inflated containers is disposed in supporting relation to the undercut blocker mass and caving is induced by pulsating the pressure of the uid in said containers by adding fluid t0 and withdrawing same from said containers from `and to a control point remotely situated with respect the mass undergoing caving.
4. An improved mining method comprising providing support for an excavated area through the medium of an inflated exible container filled with a compressed gas and bearing simultaneously on all the wall surfaces of said area in a vertical plane, whereby said container accommodates itself to the irregularities of said surfaces in said plane.
References Cited in the le of this patent UNITED STATES PATENTS 1,752,101 Meutsch Mar. 25, 1930 2,140,325 Morse Dec. 13, 1938 2,211,243 Meyer Aug. 13, 1940 2,226,201 Freyssinet Dec. 24, 1940 2,714,011 Albee July 26, 1955 2,753,036 Joy July 3, 1956 2,756,034 Calder July 24, 1956 2,861,429 Duncan Nov. 25, 1958 FOREIGN PATENTS 476,792 Germany May 29, 1929 512,197 Great Britain Aug. 30, 1939