Systems and methods for underground mining

Abstract

A method of mining and a mining system for removing material from a formation. The method comprises removing material from a formation at a mining face of a mine, capturing an image proximate to the mining face, determining a position of a target band in the formation from the image, and removing additional material from the mining face based on the position of the target band to maintain the target band at a predetermined height in the mine. The mining system comprises a mining machine having a cutter for removing material from a formation and a positioner for adjusting an orientation of the cutter, an imager for capturing images proximate to the cutter; and a processor for determining a position of target band in the formation based on images and operably coupled to the positioner for adjusting the positioning of the cutter to maintain the bands at a predetermined height.

Description

SYSTEMS AND METHODS FOR UNDERGROUND MININGFIELD OF THE INVENTION

[0001] The invention relates to methods for mining. In particular, the invention relates to controlling the orientation of a mining machine while the mining machine performs a cutting operation.BACKGROUND

[0002] Conventional underground mining techniques, such as room and pillar mining, often involve the removal of material from a formation in with relatively flat-lying deposits, such as those that follow a particular stratum, and leaves behind open spaces. However, the formation may contain bands of material disposed within that have different mechanical properties at the boundary between the bands and the rest of the formation. These boundaries where two materials meet cause stress risers, and therefore a plane of weakness.

[0003] For example, in the mining of potash near Saskatoon, Canada, the potash is found within salt beds about one kilometer beneath the surface and are separated by planar clay seams. Mining machines are used to mechanically cut and grind the potash rock to gravel-size, for transport to the surface for refinement. When material is removed according to conventional underground mining techniques, clay seams just above the area of excavation become planes of weakness, and potentially lead to fall of ground events, where portions of the roof collapse due to the delamination of thick sheets of roof rock. These failures can result in loss of equipment, working time, and risks the safety of mine personnel.

[0004] Anchoring the roofs of mines with rock bolts may help reduce the risk of fall of ground. However, this requires additional equipment and materials to be transported down to the area where mining is occurring.

[0005] There exists a need to reduce the likelihood of roof failures in mining operations.SUMMARY

[0006] In an aspect, there is provided a method of mining. The method comprises removing material from a formation at a mining face of a mine; capturing an image of the mine proximate to the mining face; determining a position of a target band in the formation from the image; and removing additional material from the mining face based on the position of the target band to maintain the target band at a predetermined height in the mine.

[0007] In some embodiments, the determining of the position of target band is based on a plurality of images captured proximate to the mining face.

[0008] In some embodiments, the determining compensates for shape of the mine. In some embodiments, the determining compensates for distortion in the image. In some embodiments, the determining comprises detecting edges of the target band.

[0009] In some embodiments, the removing additional material comprises adjusting the pitch, the roll, or both of a cutting trajectory during the removing of the additional material.

[0010] In some embodiments, the predetermined height is between 1 and 25 inches, preferably 4 and 12 inches, more preferably, 9 and 12 inches below the roof of the mine.

[0011] In some embodiments, the band comprises clay, coal, mica, talc, chlorite or a combination thereof. In some embodiments, the band comprises clay.

[0012] In some embodiments, when the removing of the material and the additional material occurs during a cutting of a first pass, the capturing of the image comprises capturing images of two side walls being created by the removing of the material. In some embodiments, when the removing of the material and the additional material occurs during a cutting of a side pass, the capturing of the image comprises capturing images of a sidewall being created by the removing of the material.

[0013] In some embodiments, the method further comprises determining positions of bands in the formation at or in a roof of the mine. In some embodiments, the method further comprises determining positions of reference bands from the captured image.

[0014] In another aspect, there is provided a mining system. The mining system comprises a mining machine having a cutter for removing material from a formation and a positioner for adjusting an orientation of the cutter. The mining system further comprises an imager for capturing images proximate to the cutter; and a processor for determining a position of target band in the formation based on images captured by the imager and operably coupled to the positioner for adjusting the positioning of the cutter to maintain the bands at a predetermined height.

[0015] In some embodiments, the mining system further comprises a formation detector for determining a position of bands in a roof of the mine.

[0016] In some embodiments, the processor is at a location that is remote from the mining machine.

[0017] In some embodiments, the cutter positioner is configured to adjust the pitch, the roll or both of the cutter.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:

[0019] FIG. 1 is a schematic diagram depicting the processing of images captured proximate to a mining face during the operation of a mining machine, and the generation of a control signal in response thereto, according to an embodiment of the invention, and

[0020] FIG. 2 is a block diagram illustrating a method of mining according to an embodiment of the invention.DETAILED DESCRIPTION

[0021] The embodiments herein will now be described in more detail with reference to the accompanying drawings, in which example embodiments are shown. Disclosed features of example embodiments may be combined. Like numbers refer to like elements throughout.

[0022] In the specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.

[0023] The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

[0024] As used herein, the term “band” means one or more generally planar layers displaying differences from adjacent layers. Bands may be continuous or discontinuous. The band may have different reflective properties of electromagnetic waves as compared to adjacent layers, for example, in ultraviolet, x-ray, or visible wavelengths, preferably in visible wavelengths. Where bands comprise certain material, they may be more susceptible to failure in the environment of a mine or a tunnel. Types of materials that tend to be prone to failure may include clay, coal, mica, talc, and chlorite. For example, clay seams are relatively prone to delamination and may result fall of ground events. Additionally, as described above, the interfaces of bands having different mechanical properties may create stress risers and, hence, planes of weakness that also increase the likelihood of failure.

[0025] In mining operations, geoscientists and / or geological engineers determine the properties of the formation, including bands that might be present in the formation. Where bands are disposed just above the roof, there is a risk that a band at the roof will delaminate, leading to a fall of ground event. It has been found that maintaining a beam of material with a thickness from the roof of the bore to a band above the roof helps maintain stability. If too much material is removed at the roof, the thickness of the beam is reduced and the risk of fall of ground events increases, as the beam would lack the strength to bear its weight.

[0026] In a sedimentary formation, for example, bands may be formed from secondary clay deposits in ancient lake or sea beds. Although generally planar, these beds may have undulations where certain areas of the ancient beds were deeper than others resulting in bands that may not have uniform depth in a formation. If mining operations were conducted at constant depth, a band that was initially disposed below the roof when material removal began may subsequently be disposed above the roof. This would result in a thin beam in the roof, with increased risk of fall of ground events. Even though the bands may be undulating, bands near each other, such as in sedimentary formations, tend to have a relatively constant thickness. By maintaining a band at a certain wall height in an excavation as the bore advances, the beam thickness in the ceiling above the excavation tends to be relatively constant. Accordingly, it may be advantageous to recognize bands in the wall to control the vertical trajectory of a mining machine.

[0027] In an aspect of the invention, there is disclosed a method of mining comprising removing material from a formation at a mining face of a mine, capturing an image of the mine proximate to the mining face, determining a position of a target band in the formation based on the image, and removing additional material from the mining face based on the position of the target band to maintain the target band at a predetermined height.

[0028] In some embodiments, the predetermined height is just below the roof of the mine. In some embodiments, the predetermined height is from 1 to 24 inches below the roof of the mine, including any subranges therein, such as from 3 to 21 , from 5 to 18, from 7 to 15, from 9 to 12 inches below the roof of the mine. In some embodiments, the predetermined height is 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, inches 24 below the roof of the mine. In some embodiments, there predetermined height includes a tolerance of ± 5, ± 4, ± 3, ± 2, ± 1 inches. For example, a predetermined height may be 10 ± 2 inches from the roof of the mine. If the predetermined height of the target band was lower from the ceiling (e.g. closer to the floor), more of the payload being targeted may be located below the target band, such that yields would suffer if too much of the overburden above the band is removed.

[0029] Further, as noted above, there may exist undulations in the sea bed leading to bands being deposited at non-uniform heights. Where a mining machine removes a horizontal swath of material as mining proceeds forward at a mining face, for example, with a borer miner or a continuous miner, the target band may be lower on one side of the mine than the other. Thus, in some embodiments, the pitch, roll or both of the mining machine is adjusted during the removal of material or additional material based on the position of the target band. This helps to ensure that the band is not disposed above the roof of the mine.

[0030] In a first pass of a mining operation, material is removed from a formation where material has not previously been removed. Thus, two side walls are created in the mine by theremoval of the material and of the additional material from the formation. In some embodiments, the capturing of the image comprises capturing images of two side walls being created by the removing of the material. This allows the adjustment of the pitch and roll of the machine during mining to maintain the position of the target band on either side of the mine.

[0031] In a side pass of a mining operation, a first pass has already been made, and material is removed beside the first pass such that the mine is widened, with one side wall of the first pass remaining in place, while the other side wall is being destroyed and a new side wall is being created. Since the position of the band has already been positioned at the predetermined height during a previous pass, the height of the roof on the side where material has previously been removed can be maintained. Thus, in some embodiments, the image is of the new side wall being created by the removing of the material. In some embodiments, the roll and pitch of the machine during the removing of additional material during a side pass may be adjusted to maintain the height of the roof on the side of the machine where material has previously been removed. In some embodiments, the method comprises determining a vertical distance from the roof, by a sensor, on the side opposite the new side wall being created.

[0032] Although the height of the target band may be controlled at either side, depending on the width of the mining machine removing material, other portions of the band may be higher in other positions of the mine, such as between the sides. In some embodiments, the method further comprises determining positions of bands in the formation at or in a roof of the mine. For example, if the target band goes above the roof of the mine, the pitch of mining machine can be adjusted such that the additional material being removed is at a higher depth such that the target band is below the roof of the mine. In some embodiments, the determining positions of bands in the formation at the roof of the mine uses sensors, such as ground penetrating radar or cameras. If the target band is identifiable by the sensor, then it may be disposed at or in the roof of the formation. For example, a ground penetrating radar may detect the target band or other bands in the roof. Alternatively or additionally, a camera that images the ceiling may be able to detect bands along a cutting path, and, based on the pitch of the cutting trajectory and / or the position of bands in the side walls, infer the position of the bands with respect to the position in and at the roof of the formation. In some embodiments, reference bands (e.g. roof reference bands) are determined above the target band by the ground penetrating radar and maintained at a certain height above the roof of the mine.

[0033] The removing of material can result in a dusty environment, making it challenging to capture images. For example, dust can accumulate on lens of cameras. Accordingly, in some embodiments, the method further comprises cleaning an imager prior to the capturing of images by the imager. The cleaning may involve a blowdown system that directs a stream of air at the imager, a wiper, a spinning lens, or other methods of cleaning the imager. Additionally, theimager may be positioned proximate, but behind the cutter. For example, in some embodiments, the imager is up to 4 feet behind the cutter. In some embodiments, the method further comprises directing ventilation by the mining face to reduce suspended particulates. The directing of ventilation may be performed, for example, by a brattice dividing a mining room behind the mining face into an intake side and an exhaust side , and a fan that directs air such that influent air from an intake side is directed to the mining face, where it entrains suspended particulate matter to form an effluent air that is removed from the mining face at the exhaust side.

[0034] Having reference to Fig. 1 , the determination of the position of the target band (e.g. a clay layer) will take raw images from the capturing and use image processing techniques, such as those known to those skilled in the art, to identify bands in the formation. These bands may not be a consolidated, continuous layer, but may instead, be made of discrete points or discontinuous sections at approximately the same depth in the formation. Thus, in some embodiments, image processing techniques are used in the determining of the position of the target band to detect the edges of the target band and discontinuities in the target band. For example, Al tools may be trained on annotated pictures to identify geological features, such as bands.

[0035] The determination may identify the location of bands relative to a reference position, such as the roof of the mine, a location on the mining machine, or a combination thereof. In some embodiments, the image is captured with a wide angle or fish-eye lens, and the determination of the positions must compensate for distortion (such as for fish-eye lenses). Further, depending on the mining machine that is used, the intersection of the room and the side wall is not square, but rounded or curved. Accordingly, in some embodiments, the determination of the positions compensates for the curvature of the corners of the mine.

[0036] Although the bands are generally planar, there may be pockets where material was not properly deposited to form a band. When mining, the band may “disappear” in certain areas, only to reappear as mining is continued. Thus, in some embodiments, the image is stored in a data store, and the determining of the position of the target band is based on a plurality of images, such as the captured image and / or the images stored in the data store. Older images provide a historical record of the positions of the band as material was removed from the formation and can be used to help predict where the target band is located if it disappears in an image or where the image cannot be properly resolved due to the dust occluding proper resolution of the mine. Further, the analysis of multiple captured images in the determination of bands may help compensate for poor image quality, such as when dust is present during excavation.

[0037] Further, in a formation, there may be more than one band. For example, there may be 2, 3, 4, or more bands in the formation between the roof and the floor of a mine (depicted inFig. 1 with 3 bands). In some formations, these bands are from deposits in the same bed and are separated by a relatively consistent height. Thus, in some embodiments, the method further comprises determining positions of at least one reference band (e.g. wall reference band) below the target band. Information about the positions of the at least one reference band, helps in the determination of the position of the target band. Thus, the reference bands help to predict the location of the target band in areas where the target band is not apparent.

[0038] The determination of the position of the target band may be conducted locally at the mining face or the mining machine, or may be conducted remotely. In embodiments where the determination requires complex computation, such as the operation of an Al tool, the processing occurs remotely. More complex computations may require processors with higher power consumption and thermal dissipation. This may not be compatible in the hot and dusty environments of a mine. Rather, the image may be transmitted to a processor at the surface for determining the position of the target band.

[0039] In some embodiments, the removing of the additional material comprises sending a process variable to a mining machine to adjust the pitch, the roll or both of a cutter of the mining machine such that when the mining machine advances to remove additional material, the target band is maintained at the predetermined height. In some embodiments, the determination is performed by a processor at the surface, which then sends the process variable to the controller of the mining machine. In other embodiments, the determination is performed by a processor of the mining machine. In yet other embodiments the process variable is sent by a human having reference to the image.

[0040] In some embodiments, the determining the position of the target band comprises determining a confidence score of the position of the target band. For example, if the quality of the images is lowered, such as due to (1 ) excessive dust, (2) the band thinning or disappearing, (3) prior images indicating that there are large changes in the height of the band, or a combination thereof, the determination may not be reliable. In such cases, the method may be paused to allow for an operator of the mining machine to assess the situation to determine whether mining should proceed or be halted at that location.

[0041] Having reference to FIG. 2, an exemplary method 100 of mining is disclosed. At step 110, material is removed from a formation at a mining face of a mine. At step 120, an image is captured of the mine proximate to the mining face. At step 130, a position of a target band in the formation is determined from the image captured at step 120. At step 160, additional material is removed from the mining face based on the position of the target band determined at step 130 to maintain the target band at a predetermined height.

[0042] In some embodiments, the step 120 comprises capturing a plurality of images and step 130, the position of the target band is determined from the plurality of images. This may, for example, compensate for low quality images.

[0043] In some embodiments, the determination of the position of the target band at step 130 includes compensating for the shape of the mine at 132. Sudden changes in the shape of a bore, such as at the transition between side walls and roofs, would create stress zones that increase the likelihood of fall of ground events if they were at right angles. Accordingly, these transitions are often rounded. When processing images captured at step 120, the position of the height may be distorted if there was no compensation for the shape of the mine.

[0044] Similarly, in some embodiments, the determination of the position of the target band at step 130 includes compensating for distortion in the image at 134. For example, the compensation can correct for distortion caused by a lens used in the capturing of an image at step 120, such as barrel distortion from wide-angle lenses.

[0045] In some embodiments, the determination of the position of the target band at step 130 includes detecting the edges of the target band at 136.

[0046] In some embodiments, the removal of additional material at step 160 further comprises adjusting the pitch, the roll, or both at 162.

[0047] In some embodiments, predetermined height is between 1 and 25, preferably 4 and 12, and more preferably 9 and 12 inches, below the roof.

[0048] In some embodiments, the bands comprise clay, coal, mica, talk, chlorite or a combination thereof. In some embodiments, the bands comprise clay,

[0049] In some embodiments where the removing of the material at 110 and the additional material at 160 is during the cutting of a first pass, the capturing of the image at 120 comprises capturing images of two side walls being created by the removing of the material at 110. In other embodiments where the removing of the material at 110 and the additional material at 160 is during the cutting of a side pass, the capturing of the image at 120 comprises capturing images of the sidewall being created by the removing of the material at 1 10. This is because the side opposite to the side wall was already excavated during a first pass or a prior side pass.

[0050] In some embodiments, the method 100 optionally includes determining positions of bands in the formation at or in a roof of the mine at step 140. In some embodiments, the target band, reference bands (e.g. roof reference bands), or both are determined at step 140. This may, for example, help determine a beam thickness or determine if the target band is in the roof. If the target band is in the roof or if the reference beams are too close to the roof of the mine, the cutting trajectory may be adjusted so that the target band becomes located below the roof orkeep the reference band at a certain height above the roof of the mine as the mining machine advances.

[0051] In some embodiments, the method 100 optionally includes determining reference bands (e.g. wall reference bands) from the captured image at 150. The reference bands may be below the target band.

[0052] It will be apparent to the skilled person that certain steps of method 100 may be omitted or reordered without departing from the scope of the invention. For example, the determinations at steps 130, 140, and 150 may be done simultaneously or in different orders. Similarly, the compensation to correct for different sources of error at 132, 134 and 136 may be done simultaneously or in different orders.

[0053] In an aspect, there is provided a mining system comprising a mining machine having a cutter for removing material from a formation and a positioner for adjusting an orientation of the cutter, an imager for capturing images proximate to the cutter, a processor for determining a position of a target band in the formation based on images from the imager, and operably coupled to the positioner to adjust the positioning of the cutter to maintain the target band at a predetermined height during the operation of the cutter.

[0054] In some embodiments, the system further comprises a formation detector for determining positions of bands in a roof of the mine. In some embodiments, the formation detector is a ground penetrating radar.

[0055] The processor can be any computing device capable of performing the determination, such as a computer, a laptop, a server, a tablet, a workstation, a mobile phone, or programmable logic controller. In some embodiments, the processor is at a location that is remote from the mining machine. In other embodiments, the processor is at the mining machine.

[0056] In some embodiments, the positioner is configured to adjust the pitch, the roll or both, of the cutter. In some embodiments, the system comprises an imager for capturing images proximate to opposite sides of the cutter, such as on two lateral sides of the cutter. In some embodiments, the system comprises an imager on each opposing lateral side of the mining machine.

[0057] In some embodiments, the imager comprises a cleaner. In some embodiments, the cleaner is a blowdown, a wiper, a spinning lens, or a combination thereof. This may be used to clean the imager prior to capturing an image to help remove dust and dirt prior and improve image quality.

[0058] In some embodiments, the system further comprises a data store to store images captured by the imager. The data store allows multiple images to be used in various image processing operations, such as determination of the location of bands in the formation.

[0059] In some embodiments, the system further comprises a brattice behind the cutter for directing an influent air to the cutter and effluent air away from the cutter.

[0060] Although the invention has been described with reference to certain specific, illustrative, non-restrictive embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure.

Claims

CLAIMS1 . A method of mining comprising: removing material from a formation at a mining face of a mine; capturing an image of the mine proximate to the mining face; determining a position of a target band in the formation from the image; and removing additional material from the mining face based on the position of the target band to maintain the target band at a predetermined height in the mine.

2. The method of 1 , wherein the determining of the position of target band is based on a plurality of images captured proximate to the mining face.

3. The method of 1 wherein the determining compensates for shape of the mine.

4. The method of 1 wherein the determining compensates for distortion in the image.

5. The method of 1 wherein the determining comprises detecting edges of the target band.

6. The method of 1 , wherein the removing additional material comprises adjusting the pitch, the roll, or both during the removing of the additional material.

7. The method of 1 , wherein the predetermined height is between 1 and 25 inches, preferably 4 and 12 inches, more preferably, 9 and 12 inches below the roof of the mine.

8. The method of 1 , wherein the band comprises clay, coal, mica, talc, chlorite or a combination thereof.

9. The method of 8, wherein the bands comprise clay.

10. The method of 1 , wherein when the removing of the material and the additional material is during a cutting of a first pass, the capturing of the image comprises capturing images of two side walls being created by the removing of the material.11 . The method of 1 , wherein when the removing of the material and the additional material is during a cutting of a side pass, the capturing of the image comprises capturing images of a sidewall being created by the removing of the material.

12. The method of 1 , further comprising determining positions of bands in the formation in a roof of the mine.

13. The method of 1 , further comprising determining positions of reference bands from the captured image.

14. A mining system comprising: a mining machine having: a cutter for removing material from a formation and a positioner for adjusting an orientation of the cutter; an imager for capturing images proximate to the cutter; and a processor for determining a position of target band in the formation based on images captured by the imager and operably coupled to the positioner for adjusting the positioning of the cutter to maintain the bands at a predetermined height.

15. The mining system of 14, further comprising a formation detector for determining a position of bands in a roof of the mine.

16. The mining system of 14, wherein the processor is at a location that is remote from the mining machine.

17. The mining system of 14, wherein the cutter positioner is configured to adjust the pitch, the roll or both of the cutter.

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