Abstract: A method of producing an underground cavity in a driving shield advance operation comprises, prior to excavation, forming an annular slot corresponding to the contour and wall thickness of the shield ahead of the shield by using hot gas jets to form the slot and to separate a core from the surrounding rock formation, advancing the shield into the annular slot, and breaking out the core under the protection of the shield. The device for producing the underground cavity comprises a tubular drive shield adapted to be advanced into the cavity and having an interior support wall on which is rotatably supported a support member having an arm carrying a gas jet lance. The gas jet lance advantageously includes at least one gas nozzle directed forwardly to form an inwardly extending cavity ahead of the shield, and one or more nozzle discharges directing the gas laterally.

Abstract: A contour miner has walker means carrying an external deck outside the formation being mined having power supply and control means for movement along the periphery of a coal seam with a reciprocating carriage having a rotary cutter for removing the coal from a work face extending inwardly below the overburden perpendicular to the seam periphery; a conveyor extends adjacent the work face and conveys the removed coal out beyond the external deck; an internal roof support-walker assembly is positioned inwardly of the formation and has hydraulic cylinder actuated movable roof supports and ground pads and hydraulic cylinders for walking forward toward the work face with dragline means moving prefabricated roof supports behind the support-walker assembly as it is moved toward the work face.

Abstract: An improved advancing mechanism for a dual auger continuous miner of the type adapted to be advanced by a pair of anchoring jack assemblies, a pair of cables extending from the anchoring jack assemblies to a pair of winch mechanisms on the sides of the frame. The mechanism includes a mounting arm mounted on each side of the frame for movement about a vertical axis, a telescoping structure extending longitudinally between each mounting arm and the associated anchoring jack assembly and hydraulic piston and cylinder units for effecting the pivotal movement of each arm and the telescoping movement of each telescoping structure.

Abstract: An operator cab and drilling assembly for a roof drilling and bolting device. The cab comprises a floor and a canopy having extensible hydraulic means for adjusting the distance between the cab floor and at least the front edge of the canopy. A horizontal rail extends along the entire length of the front edge of the floor and is spaced therefrom. A roof bolting and drilling apparatus slidably engages the horizontal rail. The rail is mounted by swinging arms to always be parallel to the cab floor.

Abstract: Shale oil is recovered from an underground oil shale deposit by in-situ retorting of rubblized shale in a retort formed in the deposit. Oil shale in a volume in the range of ten to fifty percent of the volume of the retort is mined from the deposit and delivered to the surface to provide void space for the expansion of the shale that occurs on rubblization to form the in-situ retort. The oil shale delivered to the surface is retorted at the surface. After completion of the in-situ retorting, boreholes are drilled downwardly through the retorted shale and a pipe lowered through the borehole to a level near the bottom of the retort. Spent shale from the surface retorting operation is slurried and pumped into the lower end of the in-situ retort. Pumping is continued to squeeze the slurry into the fissures between blocks of spent shale. The slurry is delivered into successively higher levels of the retort and the pumping and squeezing operation repeated at each level.

Abstract: A roll of wire mesh is supported on the rear of a cut mineral loading cowl of a rock or mineral winning machine. As the machine traverses along a path cut by the machine the wire mesh is paid out to retain or contain the roof material.

Abstract: The method of mining flat-dipping and sloping beds of a mineral with hydraulic excavation which includes dividing the bed being mined into levels and sublevels. The height of the sublevels is determined by the rock geology of the bed formation. The sublevels, in their turn, are subdivided into blocks, the width of each block being short of the limit length of the steady or self-supporting outreach of the cantilever of the rock of the main roof with the given pattern of cutting into the bed with the cutting drifts and holes defining the short working faces. The spacing of the blocks being worked in the upper and lower sublevels in the direction of strata is set to preclude inter-influence of the bearing rock pressure in the blocks where the stoping work is being done. The method enables the conduction of a stable excavation of the mineral over an extended front of stoping.

Abstract: A method for maximizing shale oil recovery from an underground oil shale formation which has previously been processed by in situ retorting such that there is provided in the formation a column of substantially intact oil shale intervening between adjacent spent retorts, which method includes the steps of back filling the spent retorts with an aqueous slurry of spent shale. The slurry is permitted to harden into a cement-like substance which stabilizes the spent retorts. Shale oil is then recovered from the intervening column of intact oil shale by retorting the column in situ, the stabilized spent retorts providing support for the newly developed retorts.

Abstract: A method of sublevel caving and pillar and top coal extraction for mining thick coal seams includes the advance mining of rooms and crosscuts along the bottom of a seam to a height of about eight feet, and the retreat mining of the top coal from the rooms, crosscuts and portions of the pillars remaining from formation of the rooms and cross-cuts. In the retreat mining, a pocket is formed in a pillar, the top coal above the pocket is drilled, charged and shot, and then the fallen coal is loaded by a continuous miner so that the operator remains under a roof which has not been shot. The top coal from that portion of the room adjacent the pocket is then mined, and another pocket is formed in the pillar. The top coal above the second pocket is mined followed by the mining of the top coal of that portion of the room adjacent the second pocket, all by use of a continuous miner which allows the operator to remain under a roof portion which has not been shot.

Abstract: A method of mining thick seam materials is performed by forming a pair of generally horizontal, vertically spaced, vertically aligned passes or drifts in one side of the thick seam. A number of contiguous vertical holes are drilled in the material from the lower to the upper drift to form a relatively large opening extending the length of the drifts. This large opening is then filled with low grade concrete to support the overburden and, after the concrete is set, a second pair of generally horizontal, vertically spaced, vertically aligned drifts are formed adjacent to the first mentioned drifts and the foregoing process is repeated. The above steps are continued until the entire seam of material has been removed.

Abstract: The mining machine consists of a main frame having a front portion and a rearwardly extending portion, and cutter heads disposed for movement across the front portion for dislodging mineral. A conveyor system is provided which extends across of the front of the main frame and along the rearwardly extending portion thereof for carrying dislodge mineral from the mine face. Forward roof support jacks, which are attached to the main frame for unitary movement therewith, provide temporary roof support as the entry is being formed. Rear roof support jacks, disposed behind the forward roof support jacks, also provide temporary roof support. Sumping cylinders, which are disposed generally parallel to the mine floor, connect the rear roof support jacks to the main frame and are used for moving the mining machine. The sumping cylinders are connected to the main frame with a universal joint connection to permit free movement of each sumping cylinder around its point of connection to the main frame.

Abstract: A method of mining a seam of rigid hydrocarbonaceous containing mineral such as oil shale or coal whereby essentially complete recovery of the mineral deposit is possible. This method comprises the steps of apportioning the seam into one or more working horizons and extracting from about 15 to about 85 percent of the mineral in a horizon using a room and pillar mining technique. The void areas resulting from the above mining operation are then filled with concrete, which is formed from cement made from spent residue and aggregate comprised of additional spent material. After the void areas are filled the remaining mineral is removed and additional concrete is deposited. Subsequently, an adjacent horizon, either above or below the initial horizon, is excavated by repeating the above steps until essentially all of the mineral deposit is recovered.

Abstract: Equipment for laying a layer of wire mesh adjacent to a newly exposed mine roof comprises storage means (10) for a roll of mesh (11) and resilient guide means (12) for guiding the mesh (72) as it unwinds towards the newly exposed mine roof (5).

Abstract: A safety wall treating method employed in the coal mining operation at the long wall face of a coal mine comprises shearing the long wall face leaving safety wall(s) at one or both side(s) of the face but shearing through the safety wall(s) at regular intervals to form intake or exhaust openings communicating with intake or exhaust tunnels.

Abstract: A method of mining a large underground seam of mineral, such as coal is described in which a first cylindrical shaft is drilled from the surface of the earth down to the mineral seam. A portion is enlarged at the base of the first shaft as a work room. A first radial shaft in the seam, out to a selected radius R, is drilled by conventional methods with the roofs supported by means such as hydraulic chocks which can be extended and moved selectively as the line of drilling progresses. When the first shaft is drilled, a continuous miner working on a short face method of mining is directly radially from the work room and is advanced outwardly until the width of the first radial shaft is such that the original wall of the first shaft has been cut away. The direction of the miner is then turned to be parallel to the first horizontal shaft and a short wall cutting advance is made to cut away the first wall of the first shaft and, in effect, drill a second shaft having a first wall spaced by the width of the cutter.

Abstract: An in situ oil shale retort having a top boundary of unfragmented formation and containing a fragmented permeable mass has a pocket at the top, that is, an open space between a portion of the top of the fragmented mass and the top boundary of unfragmented formation. To establish a combustion zone across the fragmented mass, a combustion zone is established in a portion of the fragmented mass which is proximate to the top boundary. A retort inlet mixture comprising oxygen is introduced to the fragmented mass to propagate the combustion zone across an upper portion of the fragmented mass. Simultaneously, cool fluid is introduced to the pocket to prevent overheating and thermal sloughing of formation from the top boundary into the pocket.

Abstract: A method is provided for the underground mining of thin seams of certain minerals, such as coal, particularly minerals capable of being bored or cut, employing walls formed in place. A relatively narrow substantially rectangular drift is cut in the seam, usually the entire height of the ore formation. The drift is then filled with low-grade concrete to form a wall. After the concrete has set to have sufficient compressive strength to provide support for the overburden, additional drifts are driven immediately adjacent to the wall and are joined behind the wall, so as to allow for air circulation around the wall and provide space to repeat the process. In this way, a plurality of tandem walls can be introduced through the working area of the seam. Between each tandem wall, a temporary barrier is erected, having manways with closeable doors therein as required, so that forced ventilation will travel the full length of one drift and return back through the companion drift.

Abstract: A mine roof-bolter machine having an extensible conveyor running therethrough operates behind a continuous miner machine. As the continuous miner advances, the roof-bolter advances from position-to-position while installing roof bolts and plates, and the extensible conveyor gives and takes the slack between the continuous miner and the roof bolter and feeds mined material to a surge car behind the roof bolter.

Abstract: Mining deposits, e.g., coal fields, are consolidated by injecting therein a composition which includes (a) an aqueous dispersion of a vinyl polymer, (b) at least one water-soluble acrylic monomer, and (c) a curing amount of an in situ polymerization catalyst for the acrylic monomer(s) (b); and thence permitting the composition to cure, in situ, into an adherent, consolidating gel matrix for the loose deposit.

Abstract: Shield tunneling machine and method which may minimize the variation in water- and earth-pressure at the tunneling face so as to hold the ground firm and to ensure the safe tunneling.

Abstract: An improved mining apparatus for excavating material, such as coal, for example, from an earth formation, such as a coal seam, for example, wherein a miner, having a forward and a rearward cutter, is guided through the coal seam and excavates a borehole therein, the borehole being filled with a working fluid during the operation of the miner, the working fluid facilitating the operation of the miner and providing a vehicle for removing the mined material. Substantially all of the operations of the miner are controlled from the earth's surface thereby eliminating the necessity and accompanying hazards and costs involved in utilizing personnel underground during the mining operations.

Abstract: A tunnel-excavating machine comprises an excavating head, preferably a full-cut head, adapted to excavate the full-cross-section of the tunnel to be formed, which is slideably mounted for movement relative to a pair of support frames. Means is provided to relatively displace the support frames axially and the support frames are surrounded by a blade shield made up of a multiplicity of individual blade segments, each of which can be individually advanced by hydraulic means connected to the support frames. The individual blade members, which span both frames, can be urged against the wall of the tunnel by respective fluid pressure means in each of the frames.

Abstract: A canopy and shield structure for supporting a shield adjacent a working face in a seam-like mine deposit, comprises a floor skid which is connected through an extensible and contractable prop at the working face end to the working face end of a canopy adapted to be positioned in parallel relation to the roof strata. The working space is covered at the waste removal end by a shield which includes a lower two-arm lever portion which is pivotally mounted on the skid and an upper portion which is pivotally connected to the longer arm of the two-arm lever adjacent the upper end thereof and is also pivotally connected to the canopy. The two-arm lever is driven by a hydraulic drive motor and a parallel linkage is connected between the upper shield part and the canopy in order to provide a guidance of the canopy in a direction substantially perpendicular to the strata.

Abstract: A row of horizontally spaced apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row is formed by excavating at least a pair of upper and lower retort access drifts at elevations within the top and bottom boundaries of the retort sites. The access drifts extend through opposite side boundaries of a plurality of retorts in such row. Each retort is formed by excavating upper and lower horizontal voids at the levels of the upper and lower retort access drifts, respectively, such voids being excavated laterally from the access drift within the side boundaries of the retort sites. Each retort is formed by explosively expanding formation toward the upper and lower voids within the boundaries of the retort site to form a fragmented permeable mass of particles containing oil shale in each retort.

Abstract: The mining machine has a body portion mounted on a pair of endless propelling tracks which advance the mining machine forwardly in the mine. Pairs of forwardly extending arm members are pivotally connected to the body portion and support at their end portions a skid plate which is positioned transversely across the body portion and arranged to rest on and slide over the mine floor. A first conveyor is supported by the skid plate and receives and directs dislodged material from the mine floor to a second conveyor connected to the end portion of the first conveyor. The second conveyor discharges the dislodged material to the rear of the body portion. A support frame is positioned on the skid plate and horizontally supports a pair of transverse guide rails at the front end of the body portion. A carriage is slidably mounted for transverse movement on the guide rails and includes a rotatable supporting shaft.

Abstract: Disclosed is a process for the slurry backfilling of subterranean in situ oil shale retorts, especially the improvement comprising introducing a slurry of sand and water into the subterranean retort so as to form drainage paths for the removal of water from the slurry of spent shale and water.

Abstract: A coal mining method at a long-walled pit face of a coal mine comprises combining self-advancing supports with a conveyor which is arranged along the long-walled pit face and on which a shearer is mounted, and arranging the effective shearing depth of shearing drums of the shearer to be at least half as long as the stroke of a shifter for shifting both of the self-advancing supports and the conveyor toward the pit face, whereby each of the self-advancing supports is progressively shifted toward the pit face every time that the whole area of the pit face is sheared at least twice by the shearer.

Abstract: Disclosed is a method for providing communication with a subterranean oil shale retort. This method can be used to provide a means of introducing fluids, such as a slurry of spent oil shale in water, into a retort. The method for providing lateral communication with a subterranean oil shale retort containing a rubblized retortable mass of oil shale, said retort being substantially surrounded by a mass of unmined formation comprises drilling at least one hole through the unmined formation adjacent to the retort; and providing communication between at least one of said holes and an adjacent retort; so that said drill hole can be used to communicate fluids to said retort. Fluids can be introduced into a spent retort which will form a supporting structure within said retort.

Abstract: This mining system utilizes a row of roof support units in conjunction with a row of conveyor sections and a continuous mining machine which rides on the conveyor sections. Each roof support includes a primary support shield supported on a base by means of jacks and a secondary support shield telescopically mounted to the primary support shield and having a wall engagement portion at the outer end to provide bearing support for the secondary support shield by the wall rather than merely by cantilever support. Each support unit is connected to an associated conveyor unit by a ram for moving said units relative to each other. The mining machine includes a kerf cutting member for creating a continuous ledge at the junction of the longwall and roof for supporting the secondary support shield wall engagement portion.

Abstract: Connected support sections for a mineral face conveyor are individually supported on the forward sides of chocks which move in towards the rib of a panel behind a mining machine. Backfill is transported to the mined area behind the moved-up chocks via a conveyor supported from connected support sections on the rear sides of the chocks.

Abstract: A mineral mining machine of the type having a boom-mounted cutter assembly carried by a mobile base unit is provided with a face support structure which is pivotally mounted on the boom. Fluid operable rams are provided for moving the structure between a stowed position lying adjacent the boom and an operational face supporting position perpendicular to the longitudinal axis of the boom. The face support structure is brought into operation when it is desired to afford temporary support to a face of a ripping lip for example, in arch setting operations. In this latter respect, the boom also carries a stowable platform which can be opened out so that operatives may position themselves to handle arch sections which are elevated into position by a lifting mechanism also pivotally mounted on the boom.

Abstract: The roof of an underground mine working which is newly exposed by a mining machine passing along a face of the working is supported by applying a flexible mat to the roof and underpinning the mat by self-advancing roof supports. A supply of mat is stored in a region which is already supported by the roof supports, is fed from the store in a first direction, and turned through a right-angle to extend along the newly exposed face. The device which turns the mat and applies it to the roof may have its vertical position controlled in accordance with the vertical position of a cutting cylinder of the mining machine.

Abstract: A canopy and shield structure for supporting a shield adjacent a working face in a seam-like mine deposit, comprises a floor skid which is connected through an extensible and retractable prop at the working face end to the working face, and of a canopy, which is adapted to be positioned in parallel relation to the roof strata. The working space is covered at the waste removal end by a shield which includes a lower portion pivotal on the floor skid, and an upper portion which is rigidly connected to the canopy at the opposite end of the canopy from the working face end. The shield is connectable to an extensible and retractable prop and a lemniscate guidance mechanism, so that the upper part of the shield may be moved upwardly and downwardly along its longitudinal axis. The upper part also carries an opening for the passage of a blast pipe which is supported on roller means carried by the canopy.

Abstract: A method and apparatus for successively bending and straightening a bolt shank and the like for insertion into a bolt hole is characterized by a readily transportable compact device having inner and outer spaced cooperating rollers engageable with diametrically opposed surfaces of the shank so that when the cooperating rollers are simultaneously rotated along a predetermined bending path the shank will be bent through a corresponding curvature and in a direction aligned with a bolt hole into which the shank is to be inserted. A straightener roll is disposed in the path of the shank as it becomes aligned with the bolt hole to straighten the shank prior to advancement into the hole. In the method of successively bending and straightening a bolt shank in accordance with the present invention, the shank is positioned at a substantial angle of 90.degree.

Abstract: An underground excavation method which reduces or eliminates the need for roof supports includes the cutting of one or more slots in a radial direction ahead of the advancing underground excavation. The plane of the slot is disposed perpendicular to the tangential stress that is expected around the prospective opening, so that the tangential stress is removed prior to the excavation of the opening, eliminating the potential damage to the boundary. The stress envelope finally formed after the excavation is radially expanded by the advanced slots, and can be made to stress-relieve the ground surrounding the excavation by controlling the length, number, and orientation of the advanced slots. The stress-relieved ground may be utilized as lining material by solidification with cement grouting or very limited anchor bolting.

Abstract: A method for advancing and supporting an underground mine gallery in which a groove following the outline of the cross-section of the mine gallery is formed in the mine face and simultaneously thereto a plurality of bore holes are drilled in the part of the mine face located inwardly of the groove, in which a support frame is then placed into the groove and braced against the surrounding rock, whereafter explosives placed in the bore holes are exploded to remove the part inwardly of the groove from the mine face, while the loose material formed during the preceding steps is transported away from the mine face; and a machine for carrying out the method which is advanced after the above-mentioned steps are performed, whereafter the above-mentioned steps are repeated to thus advance the underground mine gallery while properly supporting the same during such advance.

Abstract: The invention relates to the hydraulic underground mining of bituminous sands, oil shales and other friable mineral deposits. Accordingly, the invention resides in the provision of a tunnel complex at or near the base of the deposit, in which tunnels are driven parallel one with the other, and spaced a substantial distance apart. An exemplary distance would be in the region of 2,000 feet. Hydraulic excavators are driven outwardly from the sides of the tunnels until the excavator heads are in a position substantially midway between adjacent tunnels. The excavators are arranged in a multiple array at spaced intervals along the tunnels, these intervals being adjusted such that there is interaction during operation, between adjacent excavator heads. The excavators may be positioned in two or more tiers by insertion into the deposit at differing angles from the operating tunnel, such that interaction between excavators is in two dimensions, horizontal and vertical.

Abstract: In this invention there is taught the use of air tubes or fluid-filled containers to define permanent hollow tubular space within a body of solidified fill material placed in a mining excavation. The fill uses a mixture of solids and liquids with the addition of a structurally binding substance such as cement in order to make the fill substance permanent and capable of providing structural integrity and strength in the fill notwithstanding the empty tubular space. The empty tubular space can be used in accessways for mining and hauling of ore, or ventilation; it can also be used to provide volume within which to place fine component of tailings of a concentrator, or to store contaminants, or to route fill material. The tubular empty space within the fill reduces the weight, time and cost of the fill operation, and eliminates the need to drive galleries in waste rock, or of constructing costly timbered galleries or steel tubes within the stope prior to backfilling with tails.

Abstract: A method and the apparatus for implementing the method to provide temporary ground support in a mine. After an auger or other type of hole has been bored in an underground mine, at least one inflatable bladder with a fluid conduit therethrough is inserted into the hole. Once the bladder is inflated it expands to fill the hole's diameter and to act as a plug. Thereafter, fluid is forced through the fluid conduit past the bladder and into the hole cavity to act in conjunction with the bladder as a ground support for the hole. Appropriate fluid valves, meters, and conduits are placed at the input to the fluid conduit to control and measure the fluid being forced into the bladder and the hole cavity. Quick connect-disconnect couplings are provided when two or more bladders are connected seriatim and placed within the hole.

Abstract: A method of mining a large underground seam of mineral such as coal is described in which a first cylindrical shaft is drilled from the surface of the earth down to the mineral seam. A portion is enlarged at the base of the first shaft as a work room. A first radial shaft out to a selected radius R is drilled by conventional methods with the roofs supported by means such as hydraulic chocks which can be extended and moved selectively as the line of drilling progresses. When the first shaft is drilled a continuous miner working on a short face method of mining is directed radially from the work room and is advanced outwardly until the width of the first radial shaft is such that the original wall of the first shaft has been cut away. The direction of the miner is then turned to be parallel to the first horizontal shaft and a short wall cutting advance is made to cut away the first wall of the first shaft and in effect drill a second shaft having a first wall spaced by the width of the cutter.

Abstract: A bi-directional shearing machine mines a longwall face at the bottom of a thick mineral seam in a retreat operation under the protection of a row of adjacent powered roof supports each of which extends in a direction transverse to the solid face. Progressive advance of these roof supports allows the overlying mineral strata to cave. Each roof support is separated into articulated forward and aft units provided with separate sets of hydraulic props and having their solid canopies interfitted in end-to-end relation. The bases of the two units are interconnected with a push-pull hydraulic ram which enables relative longitudinal movement between the two units so that they may be advanced independently along a common axis toward the solid longwall face as the work progresses. During the advance of the forward units to provide face support, plowing and loading of caved mineral on the gob side may proceed without interruption.

Abstract: A method of backfilling in underground mine operations by a mill tailings slurry which is dewatered to provide a material with a controlled water content to permit the dewatered material to be used as a backfill without requiring any substantial dewatering after placement and which material can, when desired, be mixed with selected quantities of cement to provide a mortar for backfilling or surface covering.

Abstract: Inflatable envelope systems for use with slurry products in back filling and other operations involving subterranean works. An envelope is inflated to partially crush deformable means disposed between the envelope and the wall of an excavation chamber so as to conform to the wall profile and oppose the flow of solidifiable material between the envelope and the wall.

Abstract: Reinforcing the rock walls of a cavity comprises drilling long holes into the rock at predetermined distances and grouping and to a predetermined depth, inserting a bar-shaped tension member of high tensile strength into each of these holes and fixing their end of each member in the inner end of the respective hole. The tension members are subsequently elongated by biasing their outer ends against the cavity surface by known tension means such as screw nuts or wedges, thereby compressing the rock and preventing cracks from developing. In order to convert such cavities into tight containers, an impervious pliable sheet material is laid close to the cavity wall and held there by fastening it to the protruding ends of the tension members.

Abstract: A mining machine suitable for cutting roadways in coalmines comprises a cutting head, a conveyor for moving mined material rearwardly of the machine and a discharge conveyor for unloading the mined material to one side of the machine. As the machine advances the discharge conveyor can be used selectively to unload coal onto a stage loader and other material into packholes, thereby saving labor. The discharge conveyor may be pivotable about horizontal and/or vertical axes, longitudinally extendable or movable relative to the machine or cutting head to obtain maximum control over the area in which it discharges material.

Abstract: The specification describes a mining machine, in particular slot drilling machine for mining of minerals, especially ores of non-ferrous metals from narrow layers of reefs in hard rock, comprising at least one drilling head pivotable about a vertical pivoting axis for arcuate drilling of a slot cavity and a carrier comprising a front part and a rear part joined by thrust cylinders and hydraulic props supportable against the upper and lower slot cavity walls, characterized in the drilling head having at least one oscillation disc segment armed with at least two or preferrably more drilling tools and provided with at least one operation cylinder engaging eccentrically to the disc segment and this oscillation disc segment being supported oscillatingly in horizontal position about the vertical pivoting axis in the front part of the carrier.

Abstract: A method is provided for filling a subterranean void, e.g. a mined out cavity such as a tunnel. An aqueous suspension of solid particles the mass of which when at rest has a permeability of about 40 darcies, preferably less than 20 darcies, is injected into the void to effect complete filling.

Abstract: A miner especially adapted for high-production mining of low-coal seams (24-36 inches thick) while providing maximum miner safety and complying with applicable federal safety regulations. One or more cutting heads rotatable about the vertical axes are provided along with electric motors for rotating the heads. The heads are mounted for reciprocal longitudinal movement along the cutting face, and hydraulic cylinders, or the like, are provided for reciprocating the heads so that they move toward each other during shearing. A paddle-type conveyor continuously (even during sumping) conveys the cut coal away from the coal face, substantially perpendicular thereto through the formed tunnel. Hydraulic rams associated with roof-supporting and anchoring means are provided for sumping the cutting heads. A curtain assembly or the like contains the dust generated during cutting to a confined area adjacent the cutting face, and an exhaust fan or fans continuously draws the dust away from the confined area.

Abstract: In the mining of a thick underground mineral seam, parallel submain entries are developed at the top of the seam or at an upper level where a competent roof exists. Spaced apart parallel sets of panel entries are driven at right angles to these submain entries along a downwardly sloping path to the bottom of the seam. The entries are continued coincident with the bottom of the seam to any desired point at which their extremities are connected with bleeder entries so as to define a series of longwall panels. These panels are mined in retreat under the protection of advancing roof support structures so as to induce caving of overlying strata.

Abstract: The method of converting clayey or silty soil into stable and solid underground columns or piles suitable for carrying a building structure, comprises first the drilling of bores of a diameter considerably smaller than the external diameter of the column or pile to be created, to a predetermined depth, and secondly directing a focused laser beam gradually across the entire surface of each bore by mechanical and optical means, in such a manner that each point of the bore surface is irradiated and heated at an intensity sufficient for converting the soil surrounding the bore into a solid permanent mass of a predetermined thickness measured from the bore surface, which mass retains its strength and is resistant to moisture and temperature.