Apparatus for rotary mining

In various embodiments, a mining device can include a first housing portion and a second housing portion where relative movement between the first and second housing portions can extend and/or retract a cutting member with respect to the mining device. The mining device can further include a cable which can be mounted to the second housing portion where the cutting member is mounted to the cable and can be radially extended with respect to the first and second housing portions when the second housing portion is moved relative to the first housing portion along an axis. As the cutting member is extended, it can contact the sidewalls of a subterranean shaft to loosen material therefrom.

BACKGROUND

1. Field of the Invention

The present invention is generally directed to methods and devices for mining, and, more particularly, to methods and devices for rotary mining.

2. Description of the Related Art

Several conventional mining techniques can be employed to remove subterranean material. Such techniques commonly utilize machinery adapted to remove coal, for example, from seams that are relatively deep beneath the surface and require a network of mines comprising underground shafts and passages to access the seams. Such machinery is used to loosen material from the seams and transport the material to the surface; however, personnel are required to enter the mines to operate the machinery thereby placing them in dangerous underground conditions. Another mining technique, commonly referred to as surface, or strip, mining, is used to remove material that is relatively close to the surface. In strip mining, overlying dirt, rocks, and gravel, i.e., overburden, is removed from the ground to expose a coal seam, for example. However, strip mining often requires the use of expensive machinery to remove the overburden and often has an adverse environmental impact on the area being mined.

Other mining techniques and devices have been recently developed which solve many of the above-described problems. U.S. Pat. No. 6,065,551, for example, discloses such methods and devices. In one exemplary embodiment, a rotary mining device having radially extendable cutting members is inserted into a subterranean shaft, or bore hole, to loosen material from the sidewalls of the shaft. In such embodiments, a coal seam can be comminuted into powder, drawn up the shaft and collected when it reaches the surface. As a result, the expense of developing a network of underground passages is obviated and the surrounding environment can be substantially preserved. As disclosed therein, the cutting members are radially extended and retracted with respect to the mining device as a result of centrifugal force acting on the cutting members when the mining device is rotated. More particularly, as the rotational speed of the mining device is increased, the centrifugal force acting on the cutting members is also increased and, as a result, the cutting devices are extended further away from the mining device. Similarly, as the rotational speed on the mining device is decreased, the centrifugal force acting on the cutting members is also decreased and, as a result, springs within the mining device can retract the cutting members. Although such devices are quite successful for achieving their intended purpose, the speed of the mining device and the distance which the cutting members are extended from the mining device are directly, and indivisibly, related. As a result, the operating conditions of the mining device can be somewhat limited which can, in some circumstances, decrease the efficiency and, thus, the profitability of the mining device. What is needed is an improvement over the foregoing.

SUMMARY

In one form of the present invention, the cutting members of a mining device can be extended and retracted with respect to the mining device in a manner which is independent of the rotational speed of the mining device. In various embodiments, the mining device can include a first housing portion and a second housing portion where relative movement between the first and second housing portions can extend and/or retract the cutting members with respect to the mining device. In at least one embodiment, the mining device can include a first housing portion which defines an axis, and a second housing portion, where the second housing portion is movable relative to the first housing portion along the axis. The mining device can further include a cable which can be mounted to the second housing portion, and a cutting member mounted to the cable, where the cutting member can be configured to be rotated about the axis when the first and second housing portions are rotated about the axis. In these embodiments, the cutting member can be radially extended with respect to the axis when the second housing portion is moved relative to the first housing portion along the axis. As the cutting member is extended, it can contact the sidewalls of a subterranean shaft, or bore hole, to loosen material therefrom.

DETAILED DESCRIPTION

As outlined above, rotary mining devices, and methods for using the same, have been developed to mine material from the ground. Such devices and methods are disclosed in U.S. Pat. No. 6,065,551, entitled METHOD AND APPARATUS FOR ROTARY MINING, filed on Apr. 17, 1998, the entire disclosure of which is hereby expressly incorporated by reference herein. In use, a hole can be drilled in the ground in a vertical, horizontal, or any other suitable direction and the rotary mining device can be inserted into the hole. In other various embodiments, the mining device can be used to drill the hole. In either event, once the mining device is positioned in the hole, the mining device can be rotated therein in order to loosen or dislodge material from the sidewalls of the hole. The material can be removed from the hole as the mining device is being rotated within the hole and/or after the mining device has been withdrawn from the hole.

Referring toFIG. 1, mining device20can include first housing portion22and second housing portion24where housing portions22and24can be moved relative to each other along an axis. In the illustrated embodiment, first housing portion22can define axis26along which second housing24can be moved to deploy cutting members28, as described in further detail below. First housing portion22and second housing portion24can have any suitable cross-sectional geometry including a substantially round and/or square cross-section, for example. In various embodiments, the cross-sectional geometry of housing portions22and24can be configured such that when second housing portion24is rotated about axis26, for example, second housing portion24engages first housing portion22and rotates it about axis26. Although not illustrated, one of housing portions22and24can further include at least one key and the other of housing portions22and24can include at least one groove which co-operates with the at least one key to limit relative rotational movement between housing portions22and24.

Referring toFIG. 1, second housing portion24can include proximal end25which can be configured to be connected to the drill stem of a drilling rig, engaged to a hydraulic or electric motor, and/or rotated by a pneumatic drive system, for example. Such drive systems can provide rotational movement to second housing portion24and, in addition, translational movement to housing portion24such that housing portion24can be moved relative to first housing portion22along an axis as described above. In use, referring primarily toFIGS. 1 and 2, mining device20can be lowered into hole21such that cutting members28are substantially aligned with a seam of material sought to be extracted, such as coal, minerals, ore, shale, sand, or rock, for example. In various embodiments, as mining device20is inserted into hole21, cutting members28can be positioned against or adjacent to first housing portion22. Thereafter, mining device20can be rotated to remove material from the sidewalls of hole21.

After a period of time, owing to the rotation of cutting members28about axis26, cutting members28can clear a cylinder of material surrounding device20. Alternative embodiments are envisioned, however, in which device20is permitted to rotate eccentrically about an axis, for example, in order to clear a non-cylindrical volume of material. Stated another way, embodiments are envisioned in which first housing portion22and/or second housing portion24are rotated about an axis which is not collinear with the geometrical or symmetrical axis of device20. In either event, in order to increase the diameter of the cleared material around the mining device, cutting members28can be extended radially with respect to axis26. In various embodiments, referring toFIG. 2, the position of cutting members28relative to axis26can be controlled by relative movement between first housing portion22and second housing portion24. More particularly, referring toFIG. 1, cables30can be mounted to second housing portion24such that when distal end34of second housing portion24is moved toward distal end32of first housing portion22, slack is created in cables30which can allow the centrifugal forces acting on cutting members28, illustrated as vectors Fc inFIG. 2, to pull cutting members28outwardly and increase their radial position with respect to axis26. In effect, cutting members28can be moved between a first radial position and a second radial position with respect to axis26in a manner independent of the speed at which the mining device is rotated.

In order to generate relative movement between first housing portion22and second housing portion24as described above, first housing portion22can be positioned within the bore hole such that first housing portion22contacts the bottom of the bore hole and second housing portion24can be moved relative thereto. In circumstances where first housing portion22cannot contact the bottom of the bore hole, device20can further include a packer, such as a hook wall packer, for example, an expandable anchor, and/or any other suitable device for engaging the side walls of the bore hole. In such embodiments, first housing portion22can be selectively engaged with the side walls of the bore hole and, once engaged therewith, second housing portion24can be moved relative thereto. In at least one embodiment, as a result, a bore hole can be drilled which passes through more than one seam of material, for example, and the mining device can be positioned at different depths within the bore hole to mine the seams of material. In either event, as outlined above, device20can be positioned within a hole such that proximal end25of second housing portion24can receive a force thereto to move second housing portion24relative to first housing portion22and deploy cutting members28outwardly. In embodiments where proximal end25is positioned above the ground, such a force can be applied directly to proximal end25. In embodiments where proximal end25is positioned within the hole, a connector can be engaged with proximal end25such that the force is transmitted to proximal end25through the connector.

In various embodiments, a force can be applied to proximal end25in a periodic manner. In such embodiments, proximal end25can be moved downwardly a predetermined distance, paused, and then moved downwardly again. In such embodiments, cutting members28may be afforded an opportunity to clear the material within their radius before being moved outwardly once again. In at least one embodiment, proximal end25can be forced downwardly at a constant rate. In such embodiments, cutting members28can be extended radially at a constant rate and, if the rotational speed of cutting device20is held constant, the tangential velocity of cutting members28can be increased at a constant rate as well. In other various embodiments, proximal end25of second housing portion24can be forced downwardly at a non-constant rate. In at least one such embodiment, the rate at which proximal end25is moved downwardly and, correspondingly, the rate at which cutting members28are deployed radially, can decrease as the radius between cutting members28and axis26increases. Such embodiments may be useful where large changes in the kinetic energy of cutting members28are undesirable. Stated another way, as the kinetic energy of cutting members28is proportional to the square of the velocity of cutting members28, even small changes to the radius, and thus velocity, of cutting members28may result in large changes to the kinetic energy of cutting members28when they are radially extended at large distances.

As described above, cables30can be mounted to second housing portion24. In various embodiments, cables30can be comprised of at least one of a solid-core cable, a twisted-strand cable, a chain, a rope, a hollow tube, and/or any other ‘cable’ comprised of a suitable material. In at least one embodiment, cables30can be comprised of a directional cable which can be configured to deflect in one, or only a few, pre-selected directions. In such embodiments, the directional cable can be configured to withstand an axial load applied therto without deflecting in select directions. In any event, the term ‘cable’, as used herein, is meant to include at least the above-described embodiments and can include any suitable flexible connecting member. In various embodiments, referring toFIG. 1, mining device20can include brackets39which, when fastened to second housing portion24, can capture cables30against the outside surface thereof. Although cables30are illustrated as being mounted to the outside of housing portion24, the invention is not so limited. In various embodiments, cables30can be mounted to the interior of housing portion24or, in other embodiments, tethered to second housing portion24via apertures in housing portion24and/or projections extending therefrom in any suitable manner. In any event, cables30can be mounted to mining device20such that cables30are substantially secured to second housing portion24, or any other suitable portion of the mining device.

After a desired amount of material has been removed from the seam, for example, cutting members28can be retracted from their extended position. More particularly, distal end34of second housing portion24can be translated away from distal end32of first housing portion22by applying a force to proximal end25in order to draw cables30into cavity23of mining device20and position cutting members28against or adjacent to first housing portion22. In at least one embodiment, proximal end25of second housing portion24can be pulled upwardly by the drilling rig or motor engaged therewith, for example, in order to move housing portion24relative to first housing portion22. In various embodiments, mining device20can further include spring36which can be positioned intermediate first housing portion22and second housing portion24. Spring36can be configured to move, or push, second housing portion24upward relative to and away from first housing portion22to retract, or assist in retracting, cutting members28.

In various embodiments, referring toFIG. 2, the distance in which cutting members28are moved relative to axis26can be directly proportional to the distance in which second housing portion24is moved relative to first housing portion22. More particularly, in these embodiments, if second housing portion24is moved a distance Δd relative to first housing portion22by applying a force to proximal end25, cutting members28can move a corresponding distance Δd relative to axis26. In effect, these distances are directly related in a 1:1 relationship; however, the invention is not so limited. In various alternative embodiments, these distances can be directly related in a relationship other than 1:1, including 2:1, for example. In such embodiments, although not illustrated, the mining device can include a pulley system which can convert the change in distance Δd between first housing portion22and second housing portion24to a corresponding change in distance Δd/2 between cutting members28and axis26. In these embodiments, although the distance that cutting members28are moved relative to axis26is halved with respect to the change in distance between housing portions22and24, the mechanical advantage to retract cutting members28, for example, is doubled. In some circumstances, as a result, these mining devices can apply a greater force through cables30in order to retract cutting members28if they become stuck in the ground, for example, than mining devices having a 1:1 relationship as described above.

In various embodiments, the material removed or loosened from the sidewalls of hole21can be evacuated from hole21during the operation of mining device20. More particularly, in at least one embodiment, the rotation of cutting members28and cables30within hole21can blow the material upwardly as represented by dark arrows37inFIG. 2. In effect, cutting members28and cables30can facilitate the movement of the material upwardly through hole21. In various embodiments, mining device20can utilize pressurized air, for example, supplied thereto to push the material upwardly through hole21. In at least one embodiment, referring toFIG. 2, a conduit, although not illustrated, can be engaged with mining device20such that the pressurized air exits mining device20through aperture38and pushes the material upwardly through hole21. Mining device20can include any suitable number of apertures38which can be located in any suitable location in mining device20to achieve the above-described result. In various embodiments, although not illustrated, cables30can include an elongate aperture extending therethrough which can be configured to communicate the pressurized air to various locations along cables30including locations in, or at least adjacent to, cutting members28. In such embodiments, the flow of air and loosened material within hole21can be streamlined such that the air can flow from the outermost perimeter of hole21to its innermost portion. In other various embodiments, mining device20can be removed from hole21and the material can then be removed from hole21via a vacuum draw, for example.

As described above, cutting members28can be rotated about axis26by cables30. Cutting members28can be tethered to cables30in any suitable manner. Referring toFIG. 1, each cutting member28can include a connector29which defines a cavity31between the body of the cutting member and connector29. In at least one embodiment, an end of cable30can be passed through cavity31and then fastened, or otherwise fixed, to an adjacent portion of cable30to tether cutting member28thereto. Cutting member28, in the illustrated embodiment, can be comprised of a body having a substantially square cross-section and edges33which can extend along the length thereof and can be configured to cut material from the sidewalls of hole21.

In other various embodiments, referring toFIG. 3, cutting members128can include a frustoconical body having a major diameter140, a minor diameter142, and a tapered surface therebetween. Each cutting member128can further include cutting surfaces133extending from the frustoconical body which are configured, similar to the above, to remove material from the sidewalls of hole21. In at least one embodiment, each cutting member128can include a cavity131which is configured to receive an end of a cable130. In these embodiments, referring toFIG. 3, each cable130can include an enlarged end135which can be configured to retain cutting members128on cables130. In at least one such embodiment, enlarged end135can be press-fit within cavity131. In various embodiments, the mining device can include a drive system configured to rotate cables130and/or cutting members128about axes defined by cables130. In such embodiments, the cutting members128can impart additional energy to the surrounding material and can be especially useful when removing hard materials. In other various embodiments, enlarged end135and cavity131can be configured to allow cutting member128to rotate about cable130. In these embodiments, cutting members128, when they collide with the sidewalls of hole, can spin about cables130to reduce the amount of torque that is transferred into cables130. These features can be particularly advantageous in embodiments where cables130, when exposed to sufficient quantities of torque, could be become twisted or kinked, for example, in a manner which reduces their ability to contact the sidewalls of hole21as intended.

In various embodiments, the mining device can include recesses configured to receive at least a portion of the cutting members when the cutting members are positioned against or adjacent to the housing of the mining device. In at least one such embodiment, referring toFIG. 3, first housing portion122can include recess144which can be configured to receive a portion of a cutting member128such that the cutting member can be at least partially recessed within first housing portion122. As a result of recess144, mining device120can be more compact when it is inserted into hole21and the possibility of mining device120becoming stuck within hole21can be reduced. In various embodiments, the recesses can be contoured to substantially match the outer profile of the cutting members which can provide a snug fit therebetween. In at least one such embodiment, referring toFIG. 3, recess144can be configured to receive minor diameter142of cutting member128. In these embodiments, although the center of gravity, i.e., C.G., of the frustoconical body can be positioned outside of first housing portion122, this orientation of the frustoconical body can provide enhanced cutting capability. More particularly, it can be advantageous, in various embodiments, for the distance between the center of gravity of the cutting members and the axis of rotation of the mining device to be larger in order to have a greater inertial momentum, and energy, that can be delivered by the cutting members to the sidewalls of hole21.

Referring toFIG. 2, a mining device in accordance with an embodiment of the present invention can be positioned within hole21such that the distal tip of the mining device contacts the bottom of hole21. In one such embodiment, mining device20can include spin tip50which can include point52about which mining device20can be rotated. In the present embodiment, point52is positioned along axis26; however, in other various embodiments, point52can be positioned off-center with respect to axis26to provide an eccentric motion to mining device20when it is rotated, as described above. In various embodiments, referring toFIG. 4, the spin tip can include casters156about which cables130can be positioned. In such embodiments, casters156can facilitate the extension and/or retraction of cutting members128such that cables130do not snag or become stuck on various edges or other features of mining device120. In the illustrated embodiment, each caster156can include a groove158which can be configured to receive and guide a cable130as it is moved thereover and a pin160which can allow each caster156to rotate and thereby reduce friction between the caster and the cable. Although casters156have been described herein as being mounted to spin tip150, the invention is not so limited. On the contrary, although not illustrated, casters156can be mounted to first housing portions22and/or122, or any other suitable portion of the mining device, to achieve the above-described results.

In various alternative embodiments, mining device20can include a substantially flat base, for example, which can be configured to support mining device20on a bottom surface of a bore hole. In such embodiments, the flat base can distribute a downward force applied to first housing portion22across a large area and at least minimize the distance in which the base may sink into soft material underlying the flat base, including soft clay, for example. In embodiments where the flat base is rotated on the bottom surface of the bore hole, the base can substantially heat the surrounding material. In at least one alternative embodiment, the flat base can include a ground-contacting portion, a bearing, and a connector portion. The connector portion can be mounted to, or integrally formed with, first housing portion22where the bearing can permit relative rotation between the ground-contacting portion and first housing portion22. In such embodiments, the ground-contacting portion can remain substantially stationary when first housing portion22is rotated such that the surrounding material is not heated by the ground-contacting portion. In at least one embodiment, the ground-contacting portion can include projections extending therefrom which can be configured to engage, or grip, the ground and assist in preventing the ground-contacting portion from rotating relative to the ground.

In various embodiments, as described above, the cutting members can cut a cylinder of material, for example, surrounding the mining device where the diameter of this cylinder can be increased by moving the second housing portion relative to the first housing portion, for example, and extending the cutting members therefrom. In at least one embodiment, although not illustrated, the mining device can include a locking system configured to clamp, or otherwise limit, relative movement between the first and second housing portions. In these embodiments, after the first and second housing portions have been locked together, the mining device can be lifted and/or lowered to increase the height, h (FIG. 2), of the cylinder of removed material. Thereafter, the first and second housing portions can be unlocked and then repositioned to extend the cutting members therefrom. This process can be repeated to increase the diameter and height of the cylinder of removed material until the desired dimensions are achieved.

In various embodiments, the mining device can include several rows of cutting members. More particularly, referring toFIG. 5, mining device220can include more than one row of cutting members228which are configured to be withdrawn and retracted with respect to first housing portion222by cables230in the manners described above. Such devices can remove a cylinder of material having a greater height, h, than devices having only one row of cutting members. In other various embodiments, the mining device can include cutting members which are withdrawn and retracted by several rows of cables. More particularly, referring toFIG. 6, mining device320can include more than row of cables330which are connected to the same cutting member328. As a result of having several rows of cables330, large cutting members328can be more readily controlled than with one row of cables. In these embodiments, the dimensions of cutting members328can be configured to provide the desired height, h, of material that is removed.

In various embodiments, as outlined above, the mining devices of the present invention can be utilized to extract valuable materials from the ground. In at least one embodiment, however, the holes, or cavities, created within the ground by these mining devices can be utilized to store various materials therein including water, fuels, and/or garbage, for example. Depending of the composition of the ground, in various embodiments, such holes, or cavities, can be useful for storing natural gas. In at least one such embodiment, previously extracted natural gas can be piped into these holes and the holes can be ‘capped’ to prevent the gas from escaping therefrom. In various other embodiments, the radially extending cutting members of these mining devices can be configured to create ‘notches’ in natural gas and/or oil wells to increase the output, or production, from the wells. More particularly, in at least one embodiment, the notches can increase the surface area of a well, especially in a ‘pay zone’, in order to increase the output from the well. Stated another way, the surface area of a well is typically directly proportional to the production of the well and the mining devices disclosed herein can be utilized to increase the surface area.