CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application No. 63/114,915, entitled “ELECTROCRUSHING MINING APPARATUS”, filed on November 17, 2020, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention (Technical Field)

The present invention is related to electrocrushing mining apparatuses and methods.

Background Art

Note that the following discussion may refer to a number of publications and references. Discussion of such publications herein is given for more complete background of the scientific principles and is not to be construed as an admission that such publications are prior art for patentability determination purposes.

Electrohydraulic drilling and mining is known. In this process, an electrical arc is created in a fluid located near the rock. This produces a shockwave in the fluid which impinges on the rock, creating fractures in the rock. The rock is failed in compression because of the high pressure shockwave compressing the surface of the rock and causing it to fracture. As the shockwave reflects off the rock, it creates a pulling action on the rock that pulls the fractured pieces off. This process is very inefficient, since rock is typically about twelve times stronger in compression than in tension. Thus, it can only be used for very soft rock. Because fluid is required to produce the shockwave, it is extremely difficult if not impossible to limit excavation to a vein of ore.

Electrocrushing for drilling is also known. In this process, an electrical arc is created inside the rock, causing the rock to fail in tension. Because rock is typically about twelve times weaker in tension than in compression, this process is far more efficient than electrohydraulic drilling, providing very rapid excavation of the rock. The electrocrushing process when used for drilling is more fully disclosed in U.S. Patent Nos. 11 ,078,727; 10,961 ,782; 10,947,785; 10,407,995; 10,113,364; 10,060,195; 9,700,893; 9,190,190; 9,016,359; 9,010,458; 8,789,772; 8,616,302; 8,567,522; 8,186,454; 8,172,006; 7,959,094; 7,559,378; 7,530,406; 7,527,108; and 7,416,032, incorporated herein by reference. While electrocrushing drilling can excavate much harder rock than electrohydraulic drilling, there remains a need to be able to use an efficient mining process to follow and excavate a vein. SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)

An embodiment of the present invention is a method for mining a vein, the method comprising assembling a plurality of end effectors into an assembly having a configuration which approximately matches a shape and size of the vein, each end effector comprising a plurality of electrodes for electrocrushing material in a vein; and mining the vein along a predetermined path using the assembly. The method preferably comprises sensing a presence of the vein to minimize excavation of surrounding matrix material, preferably using a sensor technology selected from the group consisting of x-ray fluorescence, direct current (DC) resistance, radio frequency (RF) dielectric loss, magnetic- induced current, eddy current, acoustic, alternating current (AC) electric field, alternating current (AC) magnetic field, and combinations thereof. Mining the vein preferably comprises pumping mining fluid to the end effectors and separating mine cuttings from used fluid. The method optionally comprises driving an alternator with the pumped mining fluid to provide power to the end effectors, in which case communication with a controller is preferably accomplished by acoustic data transmission through the drilling fluid or RF technology. Mining the vein preferably comprises comminuting mine cuttings to a size less than approximately 1 inch; transporting the comminuted mine cuttings out of the excavation area; and transporting the comminuted mine cuttings to the surface. One or more end effectors are preferably included in each of a plurality of separate modules, each module comprising a pulsed power system, a mining fluid supply hose, and a mine cuttings transport hose, wherein the separate modules are assembled to form the assembly. Mining the vein preferably comprises steering the assembly by using different pulse rates for at least two of the end effectors. Mining the vein preferably comprises directing a path of the assembly using an inertial navigation system. The position of the assembly is optionally determined using a plurality of seismometers. Mining the vein preferably comprises propelling the assembly using one or more tractors, which preferably can be retracted into the assembly when the tractor is not in use. The assembling step is preferably performed in an underground area preferably using simple fasteners and handheld tools.

Another embodiment of the present invention is an apparatus for mining a vein, the apparatus comprising a plurality of end effectors each comprising a plurality of electrodes for electrocrushing material in a vein; one or more electrocrushing pulsed power systems; one or more mining fluid supply hoses; one or more mine cuttings transport hoses; a controller; and a mining fluid pump; wherein the plurality of end effectors are assembled into an assembly having a configuration that approximately matches a shape and size of the vein. The apparatus preferably further comprises one or more sensors for distinguishing the vein from surrounding matrix material, preferably wherein the sensors are selected from the group consisting of x-ray fluorescence sensors, direct current (DC) resistance sensors, radio frequency (RF) dielectric loss sensors, magnetic-induced current sensors, eddy current sensors, acoustic sensors, alternating current (AC) electric field sensors, alternating current (AC) magnetic field sensors, and combinations thereof. The apparatus preferably further comprises an inertial navigation system and preferably comprises one or more tractors for propelling the apparatus, which are preferably retractable into the apparatus. The assembly preferably comprises a plurality of modules, each module comprising one or more end effectors, an electrocrushing pulsed power system, a mining fluid supply hose, and a cuttings transport hose. The apparatus of preferably further comprises a separator for separating mine cuttings from mining fluid. Each electrocrushing pulsed power system optionally comprises an alternator for providing power to the end effectors, the alternator configured to be driven by mining fluid supplied to the end effectors, in which case communication with the controller is preferably accomplished by acoustic data transmission through the drilling fluid or RF technology.

Another embodiment of the present invention is a method for mining a vein, the method comprising assembling a plurality of end effectors into an assembly having a size less than a size of the vein, each end effector comprising a plurality of electrodes for electrocrushing material in a vein; mining a first slot the vein along a first predetermined path using the assembly; backing the assembly out of the first slot; offsetting a position the assembly from the first slot; and mining a second slot in the vein along a second predetermined path. The first slot and the second slot are preferably separated by a rib of vein material, the rib sufficiently wide to prevent them from collapsing. The width of the rib is optionally approximately two inches. The method preferably comprises sensing a presence of the vein to minimize excavation of surrounding matrix material, preferably using a sensor technology selected from the group consisting of x-ray fluorescence, direct current (DC) resistance, radio frequency (RF) dielectric loss, magnetic-induced current, eddy current, acoustic, alternating current (AC) electric field, alternating current (AC) magnetic field, and combinations thereof. The mining steps preferably comprise pumping mining fluid to the end effectors and separating mine cuttings from used fluid. The method optionally comprises driving an alternator with the pumped mining fluid to provide power to the end effectors, in which case communication with a controller is preferably accomplished by acoustic data transmission through the drilling fluid or RF technology. The mining steps preferably comprise comminuting mine cuttings to a size less than approximately 1 inch; transporting the comminuted mine cuttings out of the excavation area; and transporting the comminuted mine cuttings to the surface. One or more end effectors are preferably included in each of a plurality of separate modules, each module comprising a pulsed power system, a mining fluid supply hose, and a mine cuttings transport hose; wherein the separate modules are assembled to form the assembly. The mining steps preferably comprise steering the assembly by using different pulse rates for at least two the end effectors and preferably comprise directing a path of the assembly using an inertial navigation system. The position of the assembly is optionally determined using a plurality of seismometers. The mining and backing steps preferably comprise propelling the assembly using one or more tractors, and preferably further comprise retracting a tractor into the assembly when the tractor is not in use. The assembling step is preferably performed in an underground area, preferably using simple fasteners and handheld tools.

Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate the practice of embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating certain embodiments of the invention and are not to be construed as limiting the invention. In the figures:

FIG. 1 is a schematic of a single module of a vein mining machine of the present invention comprising one end effector.

FIG. 2A is a schematic of a configuration of modules for a vein mining machine of the present invention showing a rectangular array of end effectors.

FIG. 2B is a schematic of a configuration of a vein mining machine of the present invention showing a circular array of end effectors.

FIG. 3 shows the configuration of FIG. 2A comprising slots for housing retractable tractors.

FIG. 4 is a schematic of a configuration of a vein mining machine of the present invention comprising multiple end effectors sharing a single pulsed power system, mining fluid supply line, and cuttings removal line.

FIG. 5 is a schematic of a configuration of a vein mining machine of the present invention comprising multiple end effectors and a drilling fluid supply line and cutting removal line corresponding to each end effector.

FIG. 6 shows an example of how the vein mining machine of the present invention can be deployed.

FIG. 7A shows an example of a room to room vein mining strategy achievable using the present invention.

FIG. 7B displays a view across section A-A of FIG. 7A, showing an example of a roof support strategy.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

An embodiment of the present invention is an electrocrushing mining machine, called a vein miner or vein mining apparatus, which is preferably configurable to mine approximately just a vein of ore in a mine, leaving behind the surrounding rock, thereby dramatically reducing the amount of waste rock that must be transported to the surface. Almost every mine is typically designed by a mine architect or principal mine engineer, who analyzes the configuration of the vein or veins of ore, analyzes the properties of the rock formation, and models the stress in the mine with different excavation configurations. The mine architect then determines the configuration of the tunnels and the excavation process to remove the greatest amount of precious metal at the least cost. The vein miner apparatus of the present invention preferably comprises one or more discrete end effectors that can be custom configured to optimize the mining strategy selected by the mine architect. As used throughout the specification and claims, the term “vein” means vein, seam, deposit, layer, lode, bed, deposit, stratum, reef, accumulation, and the like.

FIG. 1 shows self-contained module 10 which can be used in one or more embodiments of the vein mining apparatus of the present invention. Module 10 preferably comprises end effector 20, which preferably comprises one or more positive electrodes and one or more ground electrodes for producing an electrical arc in the ore vein; pulsed power system 30, which creates an electrical pulse and feeds it to the end effector; power and data cable 40 that provides electrical power and control signals to the pulsed power system and transmits data acquired by sensors to the control system and computer; fluid supply hose 50 that provides mining fluid with the required dielectric properties to the end effectors for the electrocrushing process and sweeps out the cuttings containing the ore; and cuttings hose 60 that transports the cuttings and fluid from the end effectors out of the mining slot, optionally to a processor in the launch room. The cuttings have preferably already undergone the first stage of comminution into particles less than approximately one inch in size, more preferably approximately 0.25 inches in size. Thus the rock recovered during operation of the vein miner has already undergone the first stage of comminution, which represents a very large savings in operational costs for the mine. The end effector is preferably submerged in the mining fluid during operation. A seal for containing the fluid can be placed across the vein mine slot to enable excavating in any orientation, even vertically.

Because the vein miner apparatus of the present invention is preferably modular, the configuration can be custom configured for each mining application. A three dimensional model of the mineralization structure inside the mine is preferably developed by a mining engineer; this model describes how the veins of ore are oriented inside the ore body. The vein mining apparatus of the present invention preferably comprises a controller can take that three-dimensional model information and control the direction of the apparatus to mine out that mineralization. Because the model defines where the mineralization occurs, the apparatus is then able to mine out the ore and minimize excavation of the waste rock. For example, the apparatus can be configured to cut the span of a slot to a width of a vein according to the design of the mine by the mine architect, who analyzes the stress fields in the mine and selects the desired slot configuration to support the structure of the mine. The end effectors may be arranged in a rectangle, circle, or any other geometric shape to accommodate a cross-section vein of ore, as shown in FIGS. 2A and 2B. Changes in the diameter of the borehole or vein shaft are easily accommodated by changing the number of end effectors. In one specific hypothetical example, each end effector cuts a section of rock that is 10” x 10”. Suppose the vein is about 15 inches thick and the mine architect wants to make a 20 inch cut and has decided that a cut 50 inches wide would be appropriate for the stress structure of the mine. Ten vein miner modules would be assembled two modules high by five wide, as shown in FIG. 2A, to produce a vein miner configuration to mine out a 20” x 50” slot in the mine.

With an array of end effectors, it is possible to steer or otherwise control the direction of propagation of the apparatus by adjusting the repetition rate of each of the end effectors. The control system of the apparatus can preferably vary the repetition rate of each end effector independently. For example, referring to FIG. 2A, if the 2 x 5 vein miner apparatus needs to turn to the right, then the computer control system will preferably decrease the pulse repetition rate of the end effectors on the right side and increase the pulse repetition rate of the end effectors on the left side, causing the vein miner to excavate more rock on the left than the right, thereby steering the apparatus to the right. To enable such directional control using variable pulse rates, it is preferable that the end effectors on the edges of the apparatus are controlled by separate pulsed power systems.

The computer control system preferably receives instrumentation data from sensors to determine in which direction the apparatus should steer to follow the direction of the vein with minimal deviation. The computer then preferably provides appropriate control signals to the array of end effectors to steer the vein miner appropriately in response to the information received from the instrumentation. In this way the vein miner apparatus can effectively follow the vein of ore. The sensors can preferably provide, for example, course deviation data, which can be obtained by measuring the ratio of productive ore to surrounding rock. The apparatus may comprise an electromagnetic projector that projects an electromagnetic pulse ahead which is reflected from the mineralization in the vein and received by the sensors. The apparatus may also, or alternatively, comprise an inertial navigation system, preferably using the same attitude and heading reference system (AHRS) gyroscope technology that inertial navigation systems in modern aircraft utilize. With the use of this navigation system, the computer can direct the trajectory of the vein miner to follow a predetermined course following a vein through the mine, thus enabling autonomous control of the device.

Various sensors can be used to track the vein, as described in the following examples. X-ray fluorescence sensors are attractive because the x-rays needed to excite the fluorescence can be created by the electrocrushing pulsed power supply. For direct current (DC) resistance sensors, probes are pushed against the bore wall and the DC resistance between all adjacent probes, both longitudinally and circumferentially are preferably measured. Patterns and contrast, not absolute conductivity can be studied, and resistance changes may indicate presence of the vein. For radio frequency (RF) dielectric loss probes, the RF current depends on frequency and dielectric loss in the rock, so the currents between all adjacent pairs of probes at multiple frequencies are preferably measured. Capacitors will couple to the rock better than to the drilling mud or mining fluid (better than DC probes). Magnetic-induced current (eddy current) probes do not need to be operated in pairs since each probe can measure local eddy current magnitude and phase. The magnetic fields probe mostly rock and not drilling mud or mining fluid. Quadrature detection is commonly used in most handheld metal detectors to detect non-ferrous eddy currents, for example. For acoustic sensors, an acoustic pulse typically travels a few feet per millisecond. An ultrasound acoustic pulse provides centimeter or better resolution, and can detect a vein if there is a significant acoustic contrast between the ore or mineral vein and the surrounding matrix. Usually that means a pronounced difference in the speed of sound, or, equivalently, mechanical stiffness or density. An acoustic source can couple energy into the rock through a fluid interface, so direct contact with the rock may not be necessary. There are also non-contact methods using high frequency alternating current (AC) electric or magnetic fields. These methods measure dielectric or magnetic losses. Metallic gold, for example, would have different electrical properties than surrounding insulating quartz and crystalline granites. Numerous localized measurements are preferably made, and spatial trends are preferably analyzed.

The absolute position of the mining machine may be determined from the surface while mining. One method to track the position of the vein mining apparatus is by receiving acoustic signals from each of the rock crushing drill pulses as they arrive at the surface of the ground. It will take at least three seismometers on the surface to triangulate the position by time difference of arrival. In practice, 4 to 6 seismometers may be used to increase accuracy, to calculate an error ellipse, and to compensate for different sound speeds through various layers of rock. All signal processing is preferably performed at the surface. In this method the time between pulses is much shorter than the time it takes for the signals to travel to the surface. Many pulses will be in flight between the drill head and the surface detectors at any one time. This is a common problem in radar signal processing called range aliasing. Solutions to this problem preferably integrate over many pulses and also resolve the range ambiguity.

In one or more embodiments of the present invention, the apparatus (or one or more modules thereof) preferably comprises one or more tractors that grip the walls of the minded slot to provide forward thrust to keep the end effectors pressed against the rock, to reverse and back out of the slot (for example to cut another slot), to mine a vein that has an upward slope, to back out of a collapsing roof situation, or to otherwise move the apparatus in the mined slot. As shown in FIG. 3, tractors 70 can preferably be retracted into a dedicated opening 80 and extended when used. Operation of the tractors is preferably controlled by a computer controller.

Alternative embodiments of the present invention comprise end effectors which are separate from the other components described above, instead of a plurality of self-contained modules. For increased flexibility, any number of effectors can be driven by any number of pulsed power systems, and can be connected to any number of power and data cables, fluid supply hoses, and/or cuttings hoses. One exemplary configuration, comprising three end effectors sharing a single pulsed power system, power and data cable fluid supply hose, and cuttings hose, is shown in FIG. 4. FIG. 5 shows another exemplary embodiment that comprises three end effectors linked together to a single pulsed power system attached to a single power and data cable; however, this embodiment comprises three fluid supply hoses and three cuttings hoses, one of each corresponding to each end effector.

In some embodiments, instead of one or more power cables, the pulsed power system(s) for the end effectors may alternatively be powered by an alternator driven by the fluid flowing to the end effectors, which may be especially useful for deep mining operations or well boring or other shaft boring activities. In such a case, communication for controlling and steering the vein miner to and from a surface control computer may be accomplished by acoustic data transmission through the drilling fluid, or a similar non-cable communication technology, including RF technology.

The vein miner apparatus of the present invention can be launched from a launch room or tunnel. A launch fixture preferably orients the vein mining apparatus to intercept and track the vein at the appropriate dip angle. Vein mining apparatus 100 then excavates through the rock, tracking the location of vein 105 through the vein tracking sensors and adjusting its direction to track the deviation of vein 105, as shown in FIG. 6. The slot being cut is preferably slightly larger than the cross-sectional size of apparatus 100 itself. Support module 90 in the tunnel or launch room 95 preferably provides operational support and preferably comprises a power supply and a controller or control system computer. Support module 90 is preferably connected to the mine power to provide primary electrical power for the apparatus, and preferably converts the mine power to the voltage and current needed to power the vein mining apparatus. Support module 90 preferably comprises a pump that pumps the mining fluid to the vein miner through one or more fluid supply hoses 50 for distribution to each of the end effectors, and a separator assembly connected to cuttings hose 60 for separating the cuttings from the fluid. The fluid is preferably returned to the apparatus via a circulation pump, and the cuttings are preferably transported to the surface.

There are many mining strategies to best utilize the unique capabilities of the vein mining apparatus of the present invention. One exemplary strategy, as shown in FIG. 7 A, is to create two rooms or tunnels in the mine, each intersecting vein 105 and separated by, for example, approximately 200-500 feet. The configuration of the vein mining apparatus is preferably specified by the mine engineer, and that configuration is preferably assembled downhole in launch room 120 where support module 90 is located. Individual modules (or alternative non-module configurations as discussed above) are preferably fastened together with simple fasteners, such as bolts, and preferably can be assembled with handheld tools. The apparatus is then launched to mine vein 105 to second room 130. Once it reaches second room 130 it is preferably backed back out to launch 120 room, and then is launched to mine the next segment of vein 105 next to the first slot mined out in the first pass. In an alternative embodiment, the apparatus could mine a vein to a particular distance from the launch room, and then a second room would be cut into the mine to intersect the mined-out vein. Then after the vein was completely mined out starting from the original launch room, it and the support module can be moved to the second room and launched from there to mine out another segment of the vein.

In some cases, the mine architect may want to leave rib 150, for example about 2 inches wide, between subsequent mined out slots 160 to provide support to the mine and so that the slot will not cave in, as shown in FIG. 7B, which is a view across section (A-A) of the vein being mined in FIG. 7A. In this case the vein mining apparatus is launched with a 2 inch offset from the prior slot, and sensor instrumentation as described above is preferably used to maintain the rib width. Maintaining the correct rib width is important to provide adequate structural support to the mine. In addition to providing steering commands to the computer to steer the vein miner to maintain proper rib width, the instrumentation data also preferably provides a record of the rib width at the completion of the excavation of that segment of the vein of ore for the mine architect to analyze. In some embodiments the slot is backfilled after it is mined to provide additional roof support.

In a specific hypothetical example, vein 105 of gold ore in FIG. 7A is about 20 cm (8 inches) in thickness with a lateral extent of tens of meters. The vein has a dip angle of about 20°. Two vertical tunnels are constructed in the mine, spaced about 200 feet apart, each tunnel intersecting the vein of ore, and a room is constructed at the base of each tunnel. The mine architect has decided that supporting ribs 2 inches wide should be placed every 40 inches. Based on these requirements, the vein miner is preferably configured with five 8 inch effectors horizontally and two 8 inch effectors in the vertical direction. Although using one 8 inch effector in the vertical direction would provide a higher efficiency (as calculated below), two effector rows are required to steer up or down to track path deviations of the vein. The vein miner is then launched from the upper room and excavates the vein until it reaches the lower room. The vein miner then reverses up the slot to the upper room, where it is relaunched with a 2 inch offset in order to provide the 2 inch wide supporting rib. The vein miner then tracks the width of the rib and is steered by the computer control system to maintain the 2 inch rib width. The vein miner continues tracking the vein down to the lower room, where it then reverses and returns to the upper room to be relaunched for the next cut. The control system preferably provides the architect with a report showing the actual width of the ribs created by the vein miner. In this scenario, using typical mining equipment, if the stope or mined out slot were 5 feet in diameter, the dilution of the ore would be 7.5 times, since the stope is 7.5 times the 8 inch height of the vein. With the vein miner of the present invention cutting a 16 inch high slot to retrieve an 8 inch high vein, the dilution is only 2 times. This represents a reduction of almost 4 times in the amount of rock that needs to be transported to the surface to extract the gold.

Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a functional group” refers to one or more functional groups, and reference to “the method” includes reference to equivalent steps and methods that would be understood and appreciated by those skilled in the art, and so forth.

Although the invention has been described in detail with particular reference to the disclosed embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.