BACKGROUND
In underground hard-rock mining, a process called block caving can be used. In this process, an ore body is typically preconditioned by fracturing the ore via various methods, e.g., hydro-fracturing. Conical or tapered voids are then drilled at the bottom of the ore body, and the void is blasted. The fractured ore body above the blast will cave, and, through gravity, fall or settle down into collection areas called draw-bells. The draw-bells serve as discharge points to an entryway. Load-haul-dump vehicles typically tram through the entryway to load ore from the draw-bell. The vehicles haul the ore through various other entryways to a centrally-located dump point and dump the ore into an underground crusher that has been installed at the dump point. The crushed ore subsequently is fed to a conveyor system to be conveyed out of the mine. As additional ore is removed from the draw-bells, the ore body caves in further, providing a continuous stream of ore.
SUMMARY
In some embodiments, a material extraction system for an underground mine includes a mobile sizer for sizing removed material, an elevated bunker operable to collect the sized material, and a shuttle car operable to receive the collected material from the elevated bunker. The shuttle car is positioned substantially below the elevated bunker for receiving the collected material from the elevated bunker.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a block caving mining setup depicting an ore body, draw-bells, and undercut entryways.
FIG. 2 is a top view of a block-caving infrastructure, illustrating continuous-extraction systems according to one embodiment of the invention.
FIG. 3 is a top enlarged perspective view of the continuous-extraction system of FIG. 2, illustrating a mobile sizer, an elevated bunker, and a shuttle car.
FIG. 4 is a top enlarged perspective view of the elevated bunker of FIG. 3 with legs in an extended position.
FIG. 5 is a top perspective view similar to FIG. 4, illustrating the legs in a retracted position and coupled to drive treads in a first configuration.
FIG. 6 is a top perspective view similar to FIG. 5, illustrating the legs coupled to drive treads in a second configuration.
FIG. 7 is a top enlarged perspective view of the elevated bunker and shuttle car of FIG. 3.
FIG. 8 is a bottom perspective view of the shuttle car of FIG. 7, illustrating the shuttle car in a discharge configuration.
DETAILED DESCRIPTION
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical connections or couplings, whether direct or indirect.
FIG. 1 illustrates an underground block-caving mining process, where fractured ore body or material 2, such as copper or gold ore, caves and falls by gravity toward a series of draw-bells 4. The draw-bells 4 are discharge points to roadway entries or extraction drives 6 that extend below the fractured ore body 2 and lead to other underground entries that permit material extracted from the draw-bells 4 to be transported to the surface. With reference also to FIG. 2, a block-caving infrastructure 8 typically includes a plurality of draw-bells 4 distributed through a mining block. The block-caving infrastructure 8 can be several hundred or several thousand meters underground. In the illustrated infrastructure 8, a pair of angled draw-bell entries 9 affords access to each draw-bell 4 from adjacent roadway entries 6. Each roadway entry 6 leads to a dump point 11, which in turn leads to other entries that allow material removed from the draw-bells 4 to be transported to the surface. The dump point 11 could be an ore-pass, feeder-breaker, stationary crusher, or other dump point typically used in mining. A continuous-extraction system or material extraction system 10 is movable along the roadway entries 6 for removing fractured ore or material 2 from the draw-bell 4. Referring also to FIG. 3, the continuous-extraction system 10 includes a mobile sizer or crusher 12 for sizing the removed material, an elevated bunker 14 operable to collect the sized material, and a shuttle car 16 operable to receive the collected material from the elevated bunker 14. The shuttle car 16 is movable along the roadway entries 6 for transferring the collected material so as to facilitate a substantially continuous extraction of the material, as explained below.
With continued reference to FIG. 3, the illustrated mobile sizer 12 comprises a sizer portion 18 that is mounted on drive treads 20, a feed conveyor 22 pivotably coupled to the sizer portion 18, and a discharge conveyor 24 that carries material from the sizer portion 18 generally upwardly from a location proximal to the mine floor for discharging the sized material onto the elevated bunker 14. The mobile sizer 12 includes a self-contained power supply or drive mechanism (not shown) for moving the mobile sizer 12 along the roadway entries 6 from one draw-bell 4 to another, pushing and pulling the feed conveyor 22 for movement into and out of the draw-bell entries 9. Therefore, the mobile sizer 12 is movable along the mine floor and can be positioned anywhere along the length of the roadway entries 6. The pivotal coupling of the feed conveyor 22 allows the mobile sizer 12 to be articulated in two parts, and helps negotiate curves. Although in the illustrated embodiment the mobile sizer 12 includes the drive treads 20, other embodiments can include track-type crawlers, rubber-tired wheels, or substantially any other type of support that allows for movement of the mobile sizer 12. The mobile sizer 12 can be driven or powered by electrical, electro hydraulic, or a combination of electric and hydraulic motors, and in some embodiments may be powered at least in part by diesel power. In further embodiments, movement of the mobile sizer 12 is controlled by an automated system using inertial or other types of navigation or guidance.
In the illustrated embodiment, the feed conveyor 22 is supported by steerable wheels or treads 28 (wheels are shown in FIGS. 2 and 3) that are engageable with the mine floor. The illustrated feed conveyor 22 includes a carriage assembly 30 that is movable along the feed conveyor 22 and has mounted thereto a backhoe-type loading arm 32 for movement therewith. The loading arm 32 is operable to reach beyond the end of the feed conveyor 22 into the draw-bell 4 and to move (e.g., to pull) material onto a collection tray 34. In this regard, the illustrated mobile sizer 12 is a “self-loading” type. The illustrated loading arm 32 also includes a rock breaker 36 operable to break down large lumps of material 2 that would otherwise be too large for the loading arm 32 to collect and maneuver onto the collection tray 34. In the illustrated embodiment, the rock breaker 36 is in the form of a jack hammer, but other embodiments may include other types of rock breakers such as drills, shearing type devices, and the like. The collection tray 34 optionally includes a pair of rotating collector wheels (not shown) to guide material onto the feed conveyor 22. In operation, material 2 is pulled from the draw-bell 4 by the loading arm 32 onto the collection tray 34, and the feed conveyor 22 then conveys the material rearwardly and upwardly and deposits it onto the sizer portion 18.
In some embodiments, the mobile sizer 12 may include a funnel or other guide member (not shown) for guiding material from the feed conveyor 22 into the sizer portion 18. One or more cylindrical rollers with associated bits are mounted in the sizer portion 18 and size or crush the material 2. As explained below, the mobile sizer 12 is configured to size or crush the removed material on a substantially continuous basis. The sized material is deposited from the sizer portion 18 onto the discharge conveyor 24 and conveyed upwardly to a position substantially elevated relative to the mine floor. The discharge conveyor 24 can contain portions with different slopes. Some embodiments of the discharge conveyor 24 may also include support legs. The discharge conveyor 24 may be separate from or integral with the mobile sizer 12, and may be driven or powered by its own independent drive system or by the drive system of the mobile sizer 12. The feed conveyor 22 and the discharge conveyor 24 can employ a plate-type conveyor, an armored-face conveyor, an endless-belt type conveyor, or other conveyors that are known in the art.
The elevated bunker 14 collects the sized material from the discharge conveyor 24, and holds the sized material while the shuttle car 16 is tramming between the dump point 11 and the elevated bunker 14. In this regard, the elevated bunker 14 acts as a surge capacitor or buffer for the sized material. Referring also to FIG. 4, the illustrated elevated bunker 14 includes a collector portion 38 and two pairs of legs 40 coupled thereto. Each leg 40 is rotatably coupled to drive treads 42 engageable with the mine floor. The elevated bunker 14 is therefore movable along the mine floor and can be positioned anywhere along the length of the roadway entries 6. Although the illustrated elevated bunker 14 includes four legs 40 and corresponding drive treads 42 rotatably coupled thereto, other embodiments may utilize fewer or more legs 40 and/or drive treads 42.
In the illustrated embodiment, the collector portion 38 defines a top opening 44 for collecting material from the discharge conveyor 24 and a bottom opening 46 for dumping or dropping the collected material by gravity onto the shuttle car 16. A funnel or chute 48 is coupled to the top opening 44 for guiding the material from the discharge conveyor 24. In some embodiments, the funnel 48 can be omitted. A pair of base members or doors 50 are coupled to the bottom opening 46 for movement relative thereto between a collect configuration (see FIGS. 4-6) and a discharge configuration (see FIGS. 7 and 8). In the illustrated embodiment, each base member 50 is substantially planar. In other embodiments, however, one or both the base members 50 may assume any geometric form suitable to hold the sized material. In still other embodiments, the bottom opening 46 may be coupled to other number of base members 50. In the illustrated embodiment, each base member 50 is coupled to the bottom opening 46 at a pivot joint. An actuator (e.g., solenoid) is operable to move each base member 50 relative to the bottom opening 46 between the collect position and the discharge position. The actuator may accomplish moving the base members 50 by means of mechanical, hydraulic, pneumatic, or electric systems depending upon the capabilities and configuration of the actuator. In some embodiments, each base member 50 seals the bottom opening 46 in the closed position (e.g., along the edges or at corners of the base member 50 and bottom opening 46). In other embodiments, however, one or more base members 50 may be moved to the closed position without necessarily sealing the bottom opening 46. The bottom-dump mechanism of the elevated bunker 14 can be a quick and reliable method to discharge the collected material.
Referring to FIGS. 4-6, each illustrated leg 40 is telescopically extendable between an extended position (see FIG. 4) and a retracted position (see FIGS. 5 and 6). When the elevated bunker 14 is collecting material from the discharge conveyor 24 and dropping the collected material onto the shuttle car 16, the legs 40 are in the extended position such that sufficient clearance is created for the shuttle car 16 to fit substantially below or underneath the collector portion 38. On the other hand, after completing an operation at a given draw-bell 4 (e.g., when the collector portion 38 of the elevated bunker 14 is substantially empty), the legs 40 can be moved to the refracted position for tramming or maneuvering the elevated bunker 14 along the roadway entries 6 to another draw-bell. The roadway entries 6 can be narrow in the block-caving infrastructure 8, and thus retracting the legs 40 inwardly can help tramming or maneuvering the elevated bunker 14 in the roadway entries 6. The extended and retracted configurations may be accomplished by means of mechanical, hydraulic, pneumatic, or electric systems depending upon the capabilities and configuration of the elevated bunker 14. In some embodiments, the legs 40 may be automatically extendable and retractable in response to information received from various sensors, transducers, cameras, and the like.
Referring to FIGS. 5 and 6, each of the drive treads 42 is rotatable about a generally vertical axis 52 for movement in a variety of directions. For example, the drive treads 42 can be aligned in a direction substantially perpendicular to the roadway entry 6 (see FIGS. 4 and 5) such that the elevated bunker 14 can be moving sideways, or in a “crabbing” manner. FIG. 6 illustrates the drive treads 42 being rotated toward a direction substantially parallel to the roadway entry 6, e.g., for tramming along the roadway entry 6. In some embodiments, at least some of the drive treads 42 may be rotatably coupled to the elevated bunker 16 via a hydraulic suspension.
In the illustrated embodiment, the elevated bunker 14 includes no drive mechanisms for tramming along the roadway entries 6, and instead is hitched, towed, pushed, or pulled like a trailer, e.g., by the mobile sizer 12 or a maintenance vehicle (not shown). In other embodiments, the elevated bunker 14 may be powered or driven at least in part by the self-contained power supply or drive mechanism of the mobile sizer 12. In still other embodiments, the elevated bunker 14 may be driven by its own integrated drive system.
Referring also to FIG. 7, the shuttle car 16 is operable to receive the collected material from the elevated bunker 14. In the illustrated embodiment, the shuttle car 16 comprises a receptacle 54 and steerable wheels or treads 56 (wheels are shown in FIGS. 7 and 8) coupled thereto. Similar to the collector portion 38 of the elevated bunker 14, the receptacle 54 of the shuttle car 16 defines a top opening 58 for collecting material and a bottom opening 60 for dropping the collected material by gravity onto the dump point 11. A funnel or chute 62 is coupled to the top opening 58 for guiding the collected material from the elevated bunker 14. In some embodiments, the funnel 62 can be omitted. A pair of base members or doors 64 are coupled to the bottom opening 60 for movement relative thereto between a collect configuration and a discharge configuration. In the illustrated embodiment, each base member 64 is substantially planar. In other embodiments, however, one or both the base members 64 may assume any geometric form suitable to hold the sized material. In still other embodiments, the bottom opening 60 may be coupled to other numbers of base members 64. In the illustrated embodiment, each base member 64 is coupled to the bottom opening 60 at a pivot joint. An actuator (e.g., solenoid) is operable to move each base member 64 relative to the bottom opening 60 between the collect configuration and the discharge configuration. The actuator may accomplish moving the base members 64 by means of mechanical, hydraulic, pneumatic, or electric systems depending upon the capabilities and configuration of the actuator. In some embodiments, each base member 64 seals the bottom opening 60 in the collect position (e.g., along the edges or at corners of the base member 64 and bottom opening 60).
The illustrated wheels 56 are engageable with the mine floor, and thus the shuttle car 16 is movable along the roadway entries 6 for transferring the collected material. In other embodiments, the shuttle car 16 may instead comprise rail-car-type wheels for movement over rails. In some embodiments, the shuttle car 16 comprises a chromium carbide overlay plate, which may allow for a relatively thick plating so as to facilitate receiving dense or heavy material.
In operation, while the material is being removed, sized (if necessary), and collected at the draw-bell 4, the shuttle car 16 hauls the collected material to the dump point 11, bottom-dumps the collected material into the dump point 11, and then returns toward the elevated bunker 14. Once the shuttle car 16 is positioned substantially below the elevated bunker 14, the elevated bunker 14 drops the collected material to the shuttle car 16. The shuttle car 16 can then tram backwards toward the dump point 11 for rapidly or quickly dropping the collected material to the dump point 11. The dump point 11 is connected to a sub-level conveyor system to eventually convey the material out of the mine. While the shuttle car 16 is tramming in the fore and aft directions, the mobile sizer 12 of the continuous-extraction system 10 can continue removing and sizing the material. The material thus moves from the mobile sizer 12, to the discharge conveyor 24, to the elevated bunker 14, to the shuttle car 16, and then outside the mine, all on a substantially rapid and continuous basis. After completing an operation at a given draw-bell 4, the legs 40 of the elevated bunker 14 are moved to the retracted position. The continuous-extraction system 10 can then tram backwards until the feed conveyor 22 is once again positioned in the roadway entry 6. Next, the continuous-extraction system 10 trams further along the roadway entry 6 to the next draw-bell entry 9. Once the elevated bunker 14 is positioned at the next draw-bell entry 9, the legs 40 are moved to the extended position, and the material-loading process is repeated. In a block-cave infrastructure 8 with multiple draw-bells 4, a plurality of continuous-extraction systems 10 can be employed to further improve production rates.
By having the mobile sizer 12 positioned within the roadway entry 6 proximal to the draw-bell 4, the amount of time spent tramming by the shuttle car 16 is dramatically reduced compared to known systems that utilize massive, centrally-located underground dump points with large, immovable crusher assemblies. Known systems may also require an infrastructure in the roadway entries 6, such as haulage conveyors or conveyor belts mounted to the mine floor or to one of the walls of the roadway entries, and associated structures. However, haulage conveyors may undesirably limit the available space for maneuvering equipment in the underground roadway entries 6. Moreover, the haulage conveyors are susceptible to fly-rock damage from secondary blasting that occasionally takes place in the draw-bells 4. By utilizing the shuttle car 16, such infrastructure in the roadway entries 6 can be substantially eliminated, while improving production rates.
Because the shuttle car 16 is only required to tram the relatively short distance between the draw-bells 4 and the mobile sizer 12, the shuttle car 16 can be driven or powered at least in part by batteries or a small diesel power unit. In some embodiments, the shuttle car 16 can be powered by a hybrid unit of diesel engine and batteries, where a diesel engine runs to charge the battery, for example between high load demands, between shifts, at break times, and the like. In further embodiments, the shuttle car 16 can be powered through multiple batteries, where one or more batteries are being charged while the others are being used. The batteries, small diesel power unit, or hybrid unit can be used to drive electric and/or electro-hydraulic motors and drive systems. In some embodiments, each wheel 56 of the shuttle car 16 may include its own dedicated electronic drive that comprises, for example, an electric motor and accompanying gearbox. In this way, each wheel can be controlled independently by an associated variable frequency drive system or a chopper drive system, thus reducing or eliminating the need for mechanical transfer cases and differentials.
Some embodiments can also include automation equipment operable to position the continuous-extraction system 10 at draw-bells 4 and to control other movements as needed. For example, remote cameras can be employed to help operate the loading arm 32, move the legs 40 and/or drive treads 42 of the elevated bunker 14, and maneuver and operate the continuous-extraction system 10 into the draw-bell 4 from a remote location. Radio or cable communication links can be used to a similar extent, with or without the remote operation cameras. In some embodiments, an operator for the remote operation cameras, communication links, or both, can be located underground. In other embodiments, the operator can be located above ground. An above ground operator can be many kilometers away from the mine. In yet other embodiments, the continuous-extraction system 10 can contain position-sensing devices for automation, remote operation, or both.
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described. Various features and advantages of the invention are set forth in the following claims.
Patent Application
20140286738
