AN UNDERGROUND MINING SYSTEM FOR REDUCED COSTS, IMPROVED EFFICIENCIES, HIGHER PRODUCTIVITY AND A SAFER WORKING ENVIRONMENT THROUGH PENETRATED BLOCK EXTRACTION

Abstract

The present invention relates to a mining method including the step of forming one or more sets of gate roads. Each set of gate roads includes at least two headings typically for providing and retuning ventilation. Dead end plunge cuts extend from the sets of gate roads. Each plunge cut is formed with a continuous miner coupled to a flexible conveyor system. Each plunge cut is greater than 30 metres in length. Advantageously, narrow elongate pillars may be left between adjacent plunge cuts, thereby resulting in greater material removal per volume and improved operating costs when compared with bord and pillar mining.

Claims

1-30. (canceled)

31. An underground mining method including the steps of forming: one or more sets of underground gate roads, each set of gate roads including at least two headings; and underground dead end plunge cuts extending from the sets of gate roads, each plunge cut formed with an unmanned continuous miner and being greater than 30 metres in length with a roof that need not be supported.

32. A mining method as claimed in claim 31, involving transporting mined material from the continuous miner using unmanned transport equipment beneath the roof.

33. A mining method as claimed in claim 31, involving forming a main entry tunnel from which the sets of gate roads later extend.

34. A mining method as claimed in claim 31, involving extracting valuable material from the plunge cuts extending into one or more blocks of valuable material between adjacent sets of gate roads.

35. A mining method as claimed in claim 31, involving forming a supporting pillar between plunge cuts extending from adjacent sets of gate roads.

36. A mining method as claimed in claim 31, involving sealing each dead end plunge cut to form a ventilation barrier whilst still permitting entry of the continuous miner coupled to a flexible conveyor system.

37. A mining method as claimed in claim 31, involving supplying inert gas to the cutting face of each plunge cut.

38. A mining method as claimed in claim 31, involving remote monitoring of the working environment in each plunge cut during its formation.

39. A mining method as claimed in claim 31, involving forming the plunge cuts on one side of a set of gate roads prior to forming plunge cuts on another side of the set of gate roads.

40. A mining method as claimed in claim 31, involving introducing a suitable settable fill material into the mined out plunge cuts.

41. An underground mine including: one or more sets of underground gate roads, each set of gate roads including at least two headings; and underground dead end plunge cuts extending from the sets of gate roads, each plunge cut formed with an unmanned continuous miner, each plunge cut having a generally quadrilateral cross section and being greater than 30 metres in length with a roof that need not be supported.

42. A mine as claimed in claim 41, wherein each plunge cut is formed by transporting mined material from the continuous miner using unmanned transport equipment beneath the roof.

43. A mine as claimed in claim 42, wherein the unmanned transport equipment includes a flexible conveyor system coupled to the continuous miner or an unmanned shuttle car for shuttling mined material from the continuous miner.

44. A mine as claimed in claim 41 wherein, in each set of gate roads, one of the at least two headings can supply air whereas another of the at least two headings can return air.

45. A mine as claimed in claim 41, wherein each set of gate roads further includes one or more cut-through tunnels extending between adjacent headings providing inter connectivity between adjacent headings.

46. A mine as claimed in claim 41, further including a set of main entry tunnels from which the sets of gate roads extend.

47. A mine as claimed in claim 41, further including blocks of valuable material between adjacent sets of gate roads and into which the plunge cuts are formed.

48. A mine as claimed in claim 41, further including a supporting pillar between plunge cuts extending from adjacent sets of gate roads.

49. A mine as claimed in claim 41, wherein the plunge cuts are parallel and extend obliquely from the sets of gate roads.

50. An underground mining system including: (1) an underground mine including: one or more sets of underground gate roads, each set of gate roads including at least two headings; and underground dead end plunge cuts extending from the sets of gate roads, each plunge cut having a generally quadrilateral cross section and being greater than 30 metres in length with a roof that need not be supported; and (2) an unmanned continuous miner for forming the plunge cuts.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[0044] FIG. 1 is a plan sectional view of a underground coal mine in accordance with an embodiment of the present invention;

[0045] FIG. 2 is a perspective sectional view of the coal mine of FIG. 1 showing the ventilation;

[0046] FIG. 3 is a perspective view of an open cut mine with the mining equipment in the base of an open pit near the entrance to the mine of FIG. 1, illustrating a continuous miner coupled to a flexible conveyor system;

[0047] FIG. 4 is a plan sectional view of the system of FIG. 1 showing the continuous miner and flexible conveyor system forming a plunge cut in the mine;

[0048] FIG. 5 is a perspective view of the system of FIG. 4 showing a barrier seal at the entry of a plunge cut;

[0049] FIG. 6 shows a close up of the barrier seal of FIG. 5;

[0050] FIG. 7 is a side sectional view of the system of FIG. 5 showing inert gas provided at the cutting face;

[0051] FIG. 8 is a plan sectional view of the system of FIG. 4 showing a remote operations centre (ROC); and

[0052] FIG. 9 shows an exemplary computer display screen presented to an operator in the ROC of FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0053] According to an embodiment of the present invention, there is provided an underground coal mine 10 as shown in FIG. 1. Tunnels are formed in a coal seam of the mine 10. Elaborating further, the mine 10 includes a triplet of main headings 1, and a triplet of spaced apart sets 15 of gate roads 17, 20 extending perpendicularly from the main headings 1 (also termed “main gates” or simply “mains”). Each set 15 of gate roads includes a triplet of gate roads or separated headings 17, 20. The mine 10 further includes cut-throughs extending between adjacent gate roads 17, 20 to form rectangular support pillars 22.

[0054] The mine 10 further includes two blocks of coal (i.e. valuable material) between adjacent sets 15 of gate roads 17, 20. Parallel dead-end plunge cuts 25 are formed in the coal blocks and extending obliquely from the sets 15 of gate roads 17, 20. Advantageously, narrow elongate coal pillars 30 are also left between adjacent plunge cuts 25, thereby resulting in greater material removal per volume and improved operating costs when compared with bord and pillar mining. The pillars 30 also provide adequate roof support so that additional roof bracing is not required in the plunge cuts. A central main pillar is also formed between opposed plunge cuts 25 from adjacent sets 15.

[0055] Turning to FIG. 2, an outer gate road 20 of each set 15 can supply fresh air whereas the other outer gate road 17 returns discharge air. Appropriate ventilation control devices can be positioned within the tunnels to control air flow.

[0056] Turning to FIG. 3, in this example, the mine 10 forms part of an open cut pit bottom mine entry system 300. The system 300 includes an open cut pit 302 with entry tunnels 304 to the mine 10. The system 300 further includes a continuous miner 306 coupled to a flexible conveyor system 308 (or continuous haulage system) for forming the generally rectangular (i.e. quadrilateral) plunge cuts 25. Advantageously, the continuous miner 306 and flexible conveyor system 308 represent significantly lower initial capital costs than long wall mining. Further, the continuous miner 306 is more adaptable in following an interrupted coal seam along or through a fault line or other discontinuity.

[0057] The continuous miner 306 cuts into the face 23 of the coal seam block, and passes the cut coal from the front of the miner 306 to the rear where it is automatically unloaded onto the flexible conveyor system 308. The continuous miner 306 is a machine that cuts coal from an exposed face of a coal seam, eliminating separate cutting, drilling, blasting, and loading operations otherwise called for in other coal mining processes. Generally, a continuous miner 306 will have a rotating cutter head that moves up and down and cuts coal from the exposed face of the coal seam as the cutter head rotates.

[0058] The flexible conveyor system 308 receives coal from the continuous miner 306. The flexible conveyor system 308 is a type of continuous haulage system of variable length, and includes a series of mobile conveyors 310 which can be coupled or decoupled to accommodate the length of the plunge cuts 25 to be made into the coal seam. That is, the length of the flexible conveyor system 308 can be varied (i.e., shortened or lengthened) as needed, depending on how far into the coal seam the continuous miner 306 will penetrate.

[0059] Turning to FIG. 4, the system 300 further includes a static conveyor 400 for conveying material serially received from the flexible conveyor system 308. Accordingly, coal is automatically transferred from the miner 306 to the static belt conveyor 400 via the flexible conveyor system 308 to take the coal ultimately out of the mine. The completed plunge cuts 25 are of a depth to receive the continuous miner 306 and most of the flexible conveyor system 308. The plunge cuts are typically between 30 m and 550 m deep. Accordingly, adjacent sets of gate roads could be up to 800 m or more apart, a substantially greater separation between gate roads than in long wall mining, which further reduces the mining costs.

[0060] As shown in FIG. 5, the system 300 includes a barrier seal 500 for blocking and at least partially sealing each dead end plunge cut 25 during its formation. As can best be seen in FIG. 6, the seal includes a horizontal bar from which compliant strips hang, and is mounted in the mouth of the plunge cut 35. In use, the flexible conveyor system 308 can freely pass through the barrier seal 500.

[0061] Turning to FIG. 7, the continuous miner 306 includes an inert gas supply for supplying inert gas 700 (e.g. carbon dioxide or nitrogen) to the cutting face of each plunge cut 25 to avoid hazards such as frictional ignition, methane ignition as it is emitted from the coal or coal dust ignition in extreme events, in the plunge cut 25. The system 300 further includes sensors for sensing characteristics of the working environment in the sealed plunge cut 25 during its formation. The sensed characteristics include the gas or oxygen content along the plunge cut 25, ventilation, strata movement and dust levels in the plunge cut 25. The continuous miner 30 is unmanned, and there is no risk to any operator in the unlikely event of a collapse in the plunge cut 25.

[0062] The continuous miner 306 also includes an inertial navigation system for navigating during formation of the plunge cuts 25. The inertial navigation system includes sensors for sensing characteristics including angle (e.g. horizon control) or positioning (e.g. heading). The continuous miner 306 also includes a gamma detection device for detecting the boundary of the coal seam during excavation.

[0063] Turning to FIG. 8, the system 300 includes an operating centre (ROC) 800 for remotely operating the continuous miner 306 and greater system 300. As no machine operator is present in the cuts 25, the roof of each plunge cut 25 need not be reinforced resulting in reduced costs and time. The ROC 800 is manned and wirelessly communicates with the unmanned continuous miner over the Ethernet. The ROC advantageously limits risks to the operators relating to the mining environment including noise exposure, equipment risks, dust exposure and roof collapse.

[0064] FIG. 9 shows an exemplary computer display screen 900 presented to an operator in the ROC 800. The operator remotely monitors the working environment in the sealed plunge cut 25 during its formation. The monitoring involves monitoring miner characteristics of the continuous miner 306. The miner characteristics include actual angle (e.g. horizon control) 902 and heading (e.g. positioning) 904 which are superposed with computer calculated desired angle 906 and heading 908. The operator controls the miner 306 remotely by aligning the actual angle 902 with desired angle 906, and actual heading 904 with desired heading 908 based upon the desired layout of the mine 10. The monitoring also involves monitoring the gas, ventilation, strata movement or dust levels in the plunge cut 25 using sensors in the plunge cut 25 and the gamma detector of the miner 306.

[0065] Returning to FIG. 1, a method for forming the mine 10 is briefly described. Note that the underground mine may be developed either from an open cut excavation or from the ground surface of the mine via a set of tunnels angled downwards at a compliant slope to intersect the underground coal seam.

[0066] Initially, the main headings 1 and then gate roads are formed using a continuous miner 306.

[0067] Next, the continuous miner 306 is coupled to tow the flexible conveyor system 308. The miner 306 and system 308 then sequentially form the plunge cuts 25 firstly along the left gate road 17 and then the right gate road 20 of a given gate road set 15. First, the miner 306 extends forwards and creates a plunge cut 25, before reversing out of the plunge cut 25 and back into a retracted position, ready to form the adjacent plunge cut 25. With reference to FIG. 4, the flexible conveyor system 308 substantially enters each plunge cut 25 during its formation. The length of the flexible conveyor system 308 can be varied by changing the number of constituent conveyors 310. In addition, the normally static conveyor 400 can also be expanded or moved as required.

[0068] A person skilled in the art will appreciate that many embodiments and variations can be made without departing from the ambit of the present invention.

[0069] For example, the plunge cuts 25 can be formed at any angle of about 20 to 170 degrees to the straight coal face 23 lining the gate roads 17, 20.

[0070] In one embodiment, multiple continuous miners 306 can simultaneously form plunge cuts 25 in respective coal blocks.

[0071] In one embodiment, the flexible conveyor system 308 can be replaced by another type of continuous haulage system positioned between the continuous miner 306 and the fixed conveyor 400. For example, a variable length continuous haulage conveyor system (e.g., Flexiveyor, Prairie Machine & Parts, Saskatoon, SK, Canada), or other haulage machine/system which hauls the coal to the conveyor can be used.

[0072] In one embodiment, the plunge cuts 25 may be alternately formed on either side of a gate road set 15, rather than one side and then the other.

[0073] In one embodiment, potash may be the valuable material mined, rather than coal.

[0074] In one embodiment suitable fill material (such as a cementitous type fill or similar variant, with properties such that the fill “sets” to form a moderately strong homogenous material) may be provided into the mined out plunge cuts 25 and allowed to set. In turn, the intervening pillars 30 can then be mined using the continuous miner 306 and the flexible conveyor system 308, whilst the set fill supports the adjacent roof strata.

[0075] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

[0076] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.