WO2019204595A1

WO2019204595A1 - Method for surface mining using a conveyor system

Info

Publication number: WO2019204595A1
Application number: PCT/US2019/028110
Authority: WO
Inventors: Stephen W. KOU; Ronald R. Kelly
Original assignee: Terra Nova Technologies, Inc.
Priority date: 2018-04-20
Filing date: 2019-04-18
Publication date: 2019-10-24

Abstract

A method for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface of the mine. An extendable conveyor system having a head disposed at or near the surface of the mine and a tail disposed at a first location located beneath the surface is provided. The conveyor system defines a conveyance path that transports material from the tail to the head. The conveyor system includes an extendable fixed conveyor having a first end disposed at the head and a second end disposed at a second location that is at or above the first location. Material obtained from the mine is transported to the surface using the conveyor system.

Description

METHOD FOR SURFACE MINING USING A CONVEYOR SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/660,638 filed April 20, 2018, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to methods for surface mining. In particular, the present invention relates to methods of transporting material from hard rock mines. More particularly, the present invention relates to methods of transporting material from hard rock mines using a conveyor system.

BACKGROUND

[0003] In an open-pit surface mine, an excavation or a cut is made at the surface of a formation for extracting material, such as a desirable ore. Large amounts of materials are extracted from such mines, including desirable ores and waste rock. The removal of material is often performed in a series of stages. Such progression often results in the formation of a series of terraces in the mine, called benches. The benches extend downwards from the surface of the mine toward the bottom of the mine.

[0004] In conventional open-pit mining, material is removed from the formation by explosive blasting and by excavation using shovels. The material is then loaded onto trucks and transported to the surface of the mine, where it can be processed or transported away from the mine. Trucks and shovels provide operational flexibility since they may be deployed in varying locations within the mine as needed. This allows an operator to selectively remove material, targeting areas of the formation having high concentrations of target materials.

[0005] The dimensions of the mine, however, may become so large that it becomes unfeasible to operate a large fleet of trucks and/or shovels to accommodate a desired rate of material removal. In large mines, more than several tens of thousands of tons of material may be removed per hour, requiring fleets of tens or hundreds of trucks travelling over long and/or steep routes. As the mine expands over time, the distances that material must be trucked expands, and more trucks are needed to maintain adequate material removal rates. Since mines are often located at relatively remote locations, providing resources such as fuel and personnel to operate and maintain these trucks may become challenging and expensive. Further, there may be risks associated with operating a large fleet, such as due operator error, which are compounded with increasing fleet sizes. Procuring, operating and maintaining such fleets may be expensive and lead to costly down time. [0006] Further, mine operators may wish to reduce selectivity in favor of higher throughputs during processing. By reducing selectivity, larger volumes of material may be removed from the mine. One method of doing this may be by removing material bench by bench. This may reduce the need for mobility of the means of transporting material to the surface of the mine as material is not always obtained from disparate locations of the mine, but from predetermined locations.

[0007] There is a need for improved methods for removing material from mines. In particular, there is a need for improved methods for removing large quantities of material from open pit mines.

SUMMARY

[0008] In an aspect, there is provided a method for transporting material from a hard rock mine having a plurality of level benches extending sequentially downwards in a step-wise manner from a surface of the mine. An extendable conveyor system is provided, the system having a head located at the surface of the mine and a tail located at a bench located downwards from the surface. The conveyor system includes a fixed conveyor having a first end located at the surface and a second end located at least two benches beneath the surface. The conveyor system is located on a ramp that extends downwards from the surface and spans the plurality of benches. Material obtained from the bench having the tail of the conveyor system disposed thereon is transported. The tail of the conveyor system is then extended downward to a lower bench by moving a mobile conveyor via the ramp such that the mobile conveyor extends from the tail of the conveyor system to an extended tail disposed at the lower bench, the lower bench being one bench beneath the tail of the conveyor system prior to the extending. Material obtained from the lower bench is then transported. The extension and transport is repeated such that at least two mobile conveyors are provided. The tail of the conveyor system is extended downwards a further bench by replacing the at least two mobile conveyors with an extension of the fixed conveyor such that the second end is located at the further bench. Material obtained from the further bench is transported. Optionally, the extension of the tail is repeated by providing mobile conveyors or extending the fixed conveyor and transporting the material from the benches to where the conveyor is extended.

[0009] In an aspect, there is provided a method for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface of the mine. An extendable conveyor system having a head disposed at or near the surface of the mine and a tail disposed at a first location located beneath the surface is provided. The conveyor system defines a conveyance path that transports material from the tail to the head. The conveyor system includes an extendable fixed conveyor having a first end disposed at the head and a second end disposed at a second location that is at or above the first location. Material obtained from the mine is transported to the surface using the conveyor system.

[0010] In an embodiment, the mine includes a ramp spanning from the surface of the mine down at least a portion of the plurality of benches, wherein at least a portion of the extendable conveyor system is located on the ramp.

[0011] In an embodiment, the first location is located on the ramp at one of the benches of the plurality of benches.

[0012] In an embodiment, the extendable conveyor system includes at least one mobile conveyor sequentially extending downwards from the second end of the fixed conveyor, the at least one mobile conveyor configured to extend the conveyance path from the second end to the tail.

[0013] In an embodiment, the method further includes extending the conveyance path of the extendable conveyor system downward to a third location, lower than the first location by providing a mobile conveyor at the tail, wherein the mobile conveyor defines an extended tail.

[0014] In an embodiment, the method further includes repeating the extending of the conveyance path of the conveyor system such that at least two mobile conveyors are provided.

[0015] In an embodiment, the method further includes removing at least one mobile conveyor and extending the fixed conveyor at the second end such that the conveyance path is the same length or longer than the conveyance path prior to the extending of the fixed conveyor.

[0016] In an embodiment, the extending of the fixed conveyor comprises the addition of one or more modules chosen from span modules, intermediate drive modules, intermediate loading modules, or any combination thereof.

[0017] In an embodiment, the number of removed mobile conveyors is based on an increase of capacity based on operation of an additional drive of the fixed conveyor.

[0018] In an embodiment, further includes providing a bench conveyor having a head disposed at a location from below the head to the tail of the conveyor system, the bench conveyor system extending along a bench for transporting material obtained from the bench to the conveyor system.

[0019] In an embodiment, further includes removing at least one mobile conveyor and providing a second fixed conveyor at the tail of the system such that the conveyance path is the same length or longer than the conveyance path prior to the providing of the second fixed conveyor. [0020] In an aspect, there is provided an extendable conveyor system for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface of the mine. The system includes a head disposed at or near the surface of the mine and a tail disposed at a first location located beneath the surface. The conveyor system defines a conveyance path that transports material from the tail to the head. The system also includes an extendable fixed conveyor having a first end disposed at the head and a second end disposed at a second location that is at or above the first location. When the second location is above the first location, the system further includes at least one mobile conveyor extending the conveyance path from the second end to the tail.

[0021] In an embodiment, the mine includes a ramp extending downwards from the surface, wherein the at least a portion of the extendable conveyor and at least a portion of the at least one mobile conveyor are located on the ramp, wherein the mobile conveyors are configured to extend the system down the ramp by one bench at a time.

[0022] In an embodiment, the fixed conveyor includes a plurality of motors, wherein at least a portion of the motors are configured for operation after an extension of the fixed conveyor.

[0023] In an embodiment, a length of an extension of the fixed conveyor is chosen based on operating at least one additional motor of the plurality of motors.

[0024] In an embodiment, at least one motor of the plurality is chosen based on a length of an extension of the fixed conveyor by a predetermined number of benches.

[0025] In an embodiment, the system further includes a branch conveyor for transporting material along an intermediate bench to the fixed conveyor or one of the at least one mobile conveyors.

[0026] In an embodiment, the system further includes one or more additional fixed conveyors.

[0027] In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A is a perspective view of a conveyor system according to an embodiment shown with three mobile conveying units on a ramp.

[0029] Figure 1 B is a perspective view of a conveyor system according to the embodiment of Figure 1 where the fixed conveyor has been extended with three overland truss modules to replace the three mobile conveying units.

[0030] Figure 2A is a perspective view of a head module according to an embodiment.

[0031] Figure 2B is a perspective view of an intermediate drive module according to an embodiment.

[0032] Figure 2C is a perspective view of a take-up module according to an embodiment.

[0033] Figure 2D is a perspective view of an intermediate loading module according to an embodiment.

[0034] Figure 2E is a perspective view of an overland truss module according to an embodiment.

[0035] Figure 2F is a perspective view of an overland table module according to an embodiment of the invention.

[0036] Figure 2G is a perspective view of a tail loading module according to an embodiment.

[0037] Figure 3 is a perspective view of a mobile conveying unit according to an embodiment.

[0038] Figure 4A is a schematic diagram of a conveyor system according to an embodiment. Each horizontal grid line represents one bench of the mine.

[0039] Figure 4B is a schematic diagram of the conveyor system of Figure 4A extended with one mobile conveyor module to one bench below that of Figure 4A.

[0040] Figure 4C is a schematic diagram of the conveyor system of Figure 4A extended with two mobile conveyor modules to one bench below that of Figure 4B.

[0041] Figure 4D is a schematic diagram of the conveyor system of Figure 4A extended with three mobile conveyor modules to one bench below that of Figure 4C.

[0042] Figure 4E is a schematic diagram of the conveyor system of Figure 4A where the mobile conveyor modules added in Figures 4B to 4D have been replaced and the fixed conveyor has been extended to the lowermost bench of Figure 4D. [0043] Figure 5A is a schematic diagram of a conveyor system according to an embodiment. Each horizontal grid line represents one bench of the mine.

[0044] Figure 5B is a schematic diagram of the conveyor system of Figure 5A extended with one mobile conveyor module to one bench below that of Figure 5A.

[0045] Figure 5C is a schematic diagram of the conveyor system of Figure 5A extended with two mobile conveyor modules to one bench below that of Figure 5B.

[0046] Figure 5D is a schematic diagram of the conveyor system of Figure 5A extended with three mobile conveyor modules to one bench below that of Figure 5C.

[0047] Figure 5E is a schematic diagram of the conveyor system of Figure 5A extended with four mobile conveyor modules to one bench below that of Figure 5D.

[0048] Figure 5F is a schematic diagram of the conveyor system of Figure 5A extended with five mobile conveyor module to one bench below that of Figure 5E.

[0049] Figure 5G is a schematic diagram of the conveyor system of Figure 5A where the mobile conveyor modules added in Figures 5B to 5F have been replaced and the fixed conveyor has been extended to the lowermost bench of Figure 5F.

[0050] Figure 6 is a schematic view of a mining system according to an embodiment. The mining system includes a mine, a surface waste dump operation, a leach pad operation, and a concentrator operation.

[0051] Figure 7 A is a schematic side belt profile of a fixed conveyor according to an embodiment with two motors.

[0052] Figure 7B is a schematic side belt profile of a fixed conveyor according to an embodiment with three motors.

[0053] In the drawings, embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention.

DETAILED DESCRIPTION

[0054] As used herein, the term“about” or“approximately” preceding a recited value is to be viewed as the recited value including a tolerance range. Appropriate tolerances may be determined based on the type of measurement and the application.

[0055] Having reference to Figures 1 , 2, 3, 6 and 7, in an embodiment of the invention, there is provided a conveyor system 100 for transporting material removed from a formation 10 having a surface mine 12, such as an open pit mine, disposed therein. In some embodiments, the mine 12 is a hard rock mine. The mine 12 includes a surface 14 and descends. In some embodiments, the descent is achieved through establishing a plurality of benches 16. A ramp 18 extends down a wall face 20 of the formation 10 beginning at the surface 14 and extending down at least one bench 16. At least a portion of the conveyor system 100 is disposed on the ramp 18.

[0056] The benches 16 extend downward from the surface 14 in a terraced, step-wise manner. Each bench 16 is generally horizontally disposed, though variations may be tolerated. Material is removed from the formation 10 in long, generally linear strikes along each bench 16, extending outwards from the ramp 18. The material can be blasted by explosives and excavated by a shovel 400. The material is loaded onto the conveyor system 100 for transport to the surface 14. In some embodiments, the height of each bench is from about 9 to about 30 meters, preferably about 15 meters.

[0057] In some embodiments, the ramp 18 has a grade of from about 10% (an angle of about 6°) to about 22% (at an angle of about 12°), preferably about 20% (an angle of about 11 °). In conventional truck-based material removal, haul roads are generally limited to grades of about 10%. In some embodiments, the conveyor system is installed on an existing haul road. At higher grades, the trucks may struggle to ascend with load or to safely descend. The use of conveyors may allow the use of steeper grades. Steeper grades allow shorter conveyance lengths, which may result in reduced capital costs, reduced operational costs and increased reliability. At grades of higher than about 22%, material rollback becomes increasingly problematic. Rollback occurs when the relative movement of the material being conveyed as compared to the movement of the belt is not static; rather the material exhibits a relative downward velocity. In some embodiments, the conveyor system is installed on a purpose built ramp.

[0058] In some embodiments, the width of the ramp permits access for extension, maintenance, or other operations on the conveyor. For example, the ramp may be wide enough to allow the transport of extension modules or mobile conveyors up and/or down the ramp. In some embodiments, the ramp may have a width of from about 16 to about 25 meters, preferably about 20 meters. In some embodiments, the ramp 18 is extended prior to any extension of the conveyor system 100, as described below. In some embodiments, mine development work, such as constructing service roads, constructing secondary platforms, extending the ramp, etc. , is performed prior to any shutdown for any extension of the conveyor system 100.

[0059] In some embodiments, the mine 12 is a hard rock mine. In open-pit, hard rock mines, the mine is shaped generally as inverted conical frustum. In some embodiments, the mine is shaped as an inverted pyramidal frustum. Material removed from the formation can be processed, and waste may be redeposited or moved elsewhere, for example, in a stacking operation, such as described in US Patent No. 6,782,993, and in US Patent No. 7, 108, 124, both incorporated by reference herein. In contrast to the mines 12 exemplified above, in soft rock mines, target ores are generally disposed beneath a covering layer of overburden. Soft rock mines are often open cast mines where the overburden is removed and then redeposited in areas of the formation in which ore has been excavated. These mines are often relatively shallow and, as a result material does not have to be moved a significant distance or up in elevation.

[0060] A conveyor system 100 is provided to transport material removed from the formation 10 from the benches 16 to the surface 14. The conveyor system 100 has a head portion 102 disposed at the surface 14 of the mine 12, and a tail portion 104 disposed at a bench 16 beneath the surface 14. The conveyor system 100 defines a conveyance path 106, along which material loaded onto the conveyor system 100, such as at the tail portion 104 or an intermediate portion, is conveyed to the head portion 102. By providing a conveyor system 100, the distance that material removed from the mine must be trucked is reduced or even eliminated. In some embodiments, the conveyor system may replace tens or hundreds of trucks.

[0061] In some embodiments, the conveyor system 100 is electrically powered, diesel powered, or a combination thereof. In some preferred embodiments, at least a portion of the conveyor system is electrically powered. In some even more preferred embodiments, the conveyor system is entirely electrically powered. For example, power may be supplied to the conveyor system 100 by power lines extending from a power station. In some embodiments, the system may include diesel generators, for example, to provide backup operations or to power mobile conveyors. In some embodiments, both fixed conveyors and mobile conveyors are electrically powered. In some embodiments, the fixed conveyors and mobile conveyors are electrically connected such that power provided to one end of the conveyor system, such as at the fixed conveyor, is transmitted to other portions of the conveyor system, such as to the mobile conveyors. In some embodiments, the conveyor system 100 includes an electrical tie-in of about 100 meters from the first electrical room to a medium voltage transmission line.

[0062] In some embodiments, the conveyor system 100 includes fiber optic communication panels for upstream/downstream control and interlocks.

[0063] The conveyor system 100 includes a fixed conveyor 200 having a first end 202 disposed at or near the head portion of the conveyor system 100 and a second end 204 at a location beneath the first end 202. At least a portion of the conveyance path 106 is defined by the fixed conveyor 200. In some embodiments, the second end 204 is at a bench located beneath the first end 202.

[0064] In some embodiments, the fixed conveyor 200 includes a belt 206; at least one motor 212 for driving the belt 206, a head module 210 for transferring material from the conveyor system 100 to an ex-mine transport 600, and a tail module 250 for receiving material for transport along the conveyor system 100. For example, the conveyor system 100 transfers material being conveyed thereon to an ex-pit conveyor system. The ex-mine transport 600 is configured to transfer material from the mine 12 to another location, such as a processing facility (such as a concentrator or a leach pad) or waste dump (see Figure 6). In some embodiments, the head module 210 includes an elevated discharge, such as a head pulley discharge chute, for unloading material from the conveyor system 100. The elevated discharge allows clearance under the discharge for upstream transport equipment. The elevated discharge additionally allows for equipment, such as motors and take-up, to be disposed under the belt.

[0065] In some embodiments, the fixed conveyor 200 is modular, such that extension and function of the fixed conveyor 200 may be modified by adding, removing, and/or replacing modules as needed. In some embodiments, each module may be independently transported, for example, using trucks, self-propelled modular transporters or transport crawlers. In some embodiments, the belt 206 spans the modules of the fixed conveyor 200. In some embodiments, the modules are operationally connected such that electrical power is transmitted and/or control signals are communicated to different modules without having to provide individual power or signal lines extending to each module. In some embodiments, the weight of a module is up to about 850 tonnes.

[0066] In some embodiments, the at least one motor 212 includes a plurality of motors. For example, the at least one motor may include a head motor 212a, and at least one intermediate drive motor 212b. In some embodiments, the head module 210 includes the motor 212a (see Figure 2A). In some embodiments, the head module 210 includes two (see Figure 7A) or three head motors 212a (see Figure 7B). In some embodiments, the fixed conveyor 200 includes an intermediate drive module 220 including the at least one intermediate drive motor 212b. In some embodiments, the at least one motor 212 is located under the belt 206, preferably, under an elevated portion of the belt, such as at the head module 210 or the intermediate drive module 220. Since the belt at the head module may be elevated to discharge the conveyed material, the at least one motor may be preferentially located at or near the head. For example, the head motor 212a may be located at the head module and the intermediate drive motor 212b may be located at an intermediate drive module 220 located adjacent to the head module. [0067] When the fixed conveyor 200 is extended, additional motors may be necessary to accommodate the material being transported due to the increased length and elevation. In some embodiments, motors 212 are brought into operation as needed, cooperatively driving the belt to increase a load capacity of the conveyor system 100. The additional motors are preferably preinstalled as intermediate drive motors 212b, or added to the conveyor system during an extension. For example, a head motor 212a may be sufficient to drive the conveyor system 100 prior to an extension, but an additional head motor 212a or an intermediate drive motor 212b may be required to drive the conveyor system 100 after the extension due to increased length and material on the conveyance path 106 due to the increased length.

[0068] In some embodiments, the motor 212 includes a single stage planetary reducer with a permanent magnet motor. In some embodiments, the motor is mounted to a drive pulley on one of the modules of the fixed conveyor 200. In some embodiments, motor torque arms connect to conveyor modules through elastomeric dampeners. In some embodiments, the motors are controlled by variable frequency drives. In some embodiments, the synchronous output speed of the planetary reducer is from about 40 to about 70 rpm.

[0069] In some embodiments, the fixed conveyor 200 includes one or more span modules 230. In some embodiments, the weight of a span module 230 is from about 100 to about 250 tonnes. When transporting such modules for extending the fixed conveyor 200, one or more transport crawlers, self-propelled modular transporters or trucks may be used.

[0070] In some embodiments, at least one of the one or more span modules 230 is an overland truss module 230A. Truss modules provide good structural strength for the fixed conveyor when transporting heavy loads, such as large amounts of material. In some embodiments, overland truss modules 230 correspond in length to the bench-to-bench length on the ramp.

[0071] In some embodiments, at least one of the one or more span modules 230 is an overland table module 230B. Table modules may be used like shims at the intermediate loading point and/or the tail to adjust the length of the conveyor with finer granularity.

[0072] In some embodiments, the fixed conveyor 200 includes a take-up module 240 (see Figure 2C) located between a span module 230 and the head module 210. In some embodiments, the discharge of head module 210 is at a higher elevation from the ground than the one or more span modules 230. The higher elevation allows the transfer of material from the conveyor system 100 to another transport means, such as an ex-pit conveyor system. In some embodiments, the take-up module 240 is angled such that the elevation of the belt transitions from the one or more span modules to that of the head module 210. [0073] In some embodiments, the fixed conveyor 200 includes a tail loading module 250 (see Figure 2G). Material may be loaded onto the fixed conveyor at the tail loading module 250. In some embodiments, the tail loading module 250 includes a hopper. The hopper may receive material from a mobile crusher 500, mobile surge loader, mobile conveyor 300 or combination thereof, for loading onto the belt 206 of the conveyor system 100.

[0074] In some embodiments, the fixed conveyor 200 includes one or more intermediate loading modules 260. In some embodiments, the intermediate loading module 260 includes a hopper. The hopper may receive material from a mobile crusher 500, mobile surge loader, mobile conveyor 300 (such as a bench conveyor) or combination thereof for loading onto the belt 206 of the conveyor system 100. The intermediate loading module 260 allows for material from the mine 12 to be loaded onto the conveyor system 100 at a location between the head portion 102 and the tail portion 104. In some embodiments, the intermediate loading modules 260 allow material removed from more than one bench 16 of the formation 10 concurrently to be loaded onto the conveyor system 100. This increases the removal capacity of the mine 12.

[0075] In some embodiments, the fixed conveyor 200 may include brakes, backstops, belt cleaners, scrapers, pulleys, or other components to improve the function of the conveyor.

[0076] Where mechanical backstops having the required torque holding capacity are not available, brakes may hold the belt to prevent conveyor roll-back. In some embodiments, the fixed conveyor includes a plurality of brakes. In some embodiments, the plurality of brakes includes disc brakes. In some embodiments, the disc brakes include caliper style disc brakes. The disc brakes may be mounted to drive pulley shafts on opposite ends from the motors. In some embodiments, there are six calipers per disc. In some embodiments, the brakes include a hydraulically released fail-to-safe for applying the brakes. In some embodiments, the brakes apply constant torque. In some embodiments, the brakes are controlled individually.

[0077] In some embodiments, the fixed conveyor includes one or more belt cleaners. In some embodiments, a head pulley located at a head module includes primary and secondary scraper-type belt cleaners. In some embodiments, the tail loading module includes a vee-type belt plow.

[0078] The belt 206 spans across the various modules of the fixed conveyor 200. The belt 206 includes a conveying surface 206a for receiving and transporting material loaded onto the conveying surface and a drive surface 206b that is engaged by the at least one motor 212 for driving the belt 206. In some embodiments, the belt 206 may be spliced, for example, when extending the length of the fixed conveyor 200. In some embodiments, the belt has a width of from about 1800 to about 3150 mm. In some embodiments, the belt is driven at a speed of from about 3 to about 7 m/s. In some embodiments, the fixed conveyor has a vertical curve radius of from about 1000 to about 3000 m. In some embodiments, the belt is reinforced with steel cord. In some embodiments, the belt 206 has a tension rating of from about 5000 to about 10000 N/mm. In some embodiments, the belt has a top cover of grade DIN X. In some embodiments, the belt has a top cover with polyamide breaker cords. In some embodiments, the belt has a bottom cover of grade DIN X.

[0079] In some embodiments, one or more of the modules of the fixed conveyors 200 include at least one pulley 270. In some embodiments, the pulleys 270 include drive pulleys. In some embodiments, the drive pulleys have a diameter of from about 1800 to about 2500 mm, with ceramic lagging. In some embodiments, the pulleys 270 include a high tension bend pulley, a medium tension bend pulley, a low tension bend pulley or any combination thereof. In some embodiments, the head module includes a high tension bend pulley, a medium tension bend pulley, or both. In some embodiments, the high tension bend pulley and/or the medium tension bend pulley has a diameter of from about 1800 to about 2500 mm with rubber lagging. In some embodiments, the tail loading module, the take-up module or both include one or more low tension pulleys. In some embodiments, the low tension pulley has a diameter of from about 1400 to about 2200 mm with rubber lagging. In some embodiments, the pulleys 270 include a snub pulley. In some embodiments, the snub pulley has a diameter of from about 600 to about 1400 with rubber lagging.

[0080] In some embodiments, the fixed conveyor 200 includes a plurality of idlers. The plurality of idlers may be chosen from carry idlers, return idlers, impact idlers, or a combination thereof. In some embodiments, the carry idlers include 3 or 5 rolls with 30 to 40 degree troughing. In some embodiments, the carry idlers include rigid idler frames. In some embodiments, the return idlers include 1 , 2 or 3 rolls with 0 to 20 degree troughing. In some embodiments, the return idlers include rigid steel idler frames. In some embodiments, the impact idlers include 3 or 5 rolls with 30 to 40 degree troughing. In some embodiments, the impact idlers are Garland (caternary) type idlers.

[0081] In some embodiments, the fixed conveyor includes a constant tension take-up. In some embodiments, the constant tension take-up includes one or more equalized constant tension winches. In some embodiments, the winches are electromechanical. In some embodiments, the winches include motors driven by variable frequency drives. In some embodiments, each winch drum includes at least one caliper style disc brake. In some embodiments, a drive-line disc brake is provided. In some embodiments, the drive-line disc brake is located on a high speed shaft of the winch reducer. The winch drum brakes and/or the drive-line disc brake may include fail-safe springs for hydraulically releasing the brakes. In some embodiments, the constant tension take-up tightens the belt 206 to a target belt line tension. In some embodiments, the constant tension take-up includes a load cell to measure belt line tension.

[0082] Since, in some embodiments, the conveyor system 100 is located on an angled ramp 18, the conveyance of material from the mine 12 may produce undesirable motion, such as shaking, skidding or sliding. In some embodiments, the fixed conveyor system 200 is anchored into the formation 10 to provide increased stability. In some embodiments, the fixed conveyor 200 includes micropiles for anchoring into the formation.

[0083] In some embodiments, the conveyor system 100 optionally includes one or more mobile conveyor units 300 (see Figure 3). The one or more mobile conveyors 300 sequentially extend from the second end 204 of the fixed conveyor 200 such that the conveyance path 106 includes the fixed conveyor 200 and the one or more mobile conveyors 300. In some embodiments, each mobile conveyor 300 extends the conveyance path 106 downwards by one bench 16. In some embodiments, the mobile conveyor units 300 are as described in US6782993 and US7108124, which are incorporated herein, by reference.

[0084] In some embodiments, the mobile conveyor units 300 are Super Portable® conveyors available from Terra Nova Technologies, Inc. In some embodiments, each mobile conveyor includes a luffing head portion, an intermediate portion, a tail portion, a mobile conveyor belt, and at least one mobile motor for driving the mobile conveyor belt. In some embodiments, each mobile conveyor includes a movement portion for moving the mobile conveyor from one location to another. In some embodiments, the movement portion includes at least one crawler track undercarriage. In some embodiments, the at least one crawler track undercarriage includes dual crawler tracks. In some embodiments, the at least one crawler track undercarriage is rotatable. In some embodiments the at least one crawler track undercarriage is located at the middle, fore, aft, or any combination thereof, of the intermediate portion.

[0085] Having reference to Figures 4A-E, there is provided a method for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface 14 of the mine 12. The method includes providing an extendable conveyor system 100 having a head 102 disposed at or near the surface 14 of the mine 12 and a tail 104 disposed at a bench 16 located beneath the surface 14. The conveyor system 100 includes a fixed conveyor 200 having a first end 202 disposed at the head 102 and extends downwards at least two benches 16 beneath the surface 14. Material obtained from the mine 12 is transported to the surface 14 using the conveyor system 100.

[0086] In some embodiments, in an initial state, the conveyor system 100 consists of the fixed conveyor 200 (see Figure 4A). In such embodiments, the head 102 coincides with the first end 202 and the tail 104 coincides with the second end 204. Material is removed from the formation 10 at the bench 16 where the tail 104 is located.

[0087] In some embodiments, the conveyance path 106 of the conveyor system 100 is extended by providing at least one mobile conveyor unit 300, extending the fixed conveyor system, or a combination thereof such that the tail portion 104 is further downwards in the mine 12 than its position prior to the extension. In some embodiments, the conveyor system 100 is extended incrementally such that the tail portion 104 is shifted progressively lower in the mine 12. The lower tail portion 104 allows the removal of material from lower in the mine with the conveyor system 100. In some embodiments, the incremental extension is a bench- by-bench extension.

[0088] In some embodiments, the conveyor system 100 is extended downward to a lower bench by providing a mobile conveyor 300 at the second end 204 of the fixed conveyor 200 (Figure 4B). In some embodiments, the lower bench is one bench below the previous location of the tail portion 104. Material may then be removed from the formation 10 at the lower bench 16 and loaded onto the conveyor system 100. In other embodiments, a plurality of mobile conveyors may be provided to extend the conveyor system downward to a lower bench. In preferred embodiments, the extension will be to a lower bench, and not a location on a ramp between two benches.

[0089] In some embodiments, the conveyor system 100 may be further extended by providing additional mobile conveyor units 300 sequentially such that they are lined in a series (see, for example, Figures 4C-D). This allows material to be removed from progressively lower benches and loaded onto the conveyor system 100. In some embodiments, the conveyor system 100 is extended by providing at least two, three, four, or even five mobile conveyor units 300.

[0090] In some embodiments, the fixed conveyor 200 is extended (see Figures 1 B and 4E). In some embodiments, at least some of the mobile conveyor units 300 are removed from the conveyor system 100 and the extension of the fixed conveyor replaces or extends the length of the conveyance path 106 of the removed mobile conveyor units 300. In some embodiments, all of the mobile conveyor units 300 are removed during the extension of the fixed conveyor 200. By replacing all of the mobile conveyor units 300, wear and tear on the mobile conveyor units may be reduced, and maintenance may be performed on the mobile conveyor units while they are offline. In some embodiments, the extension of the fixed conveyor 200 extends the conveyance path 106 further than the conveyance path 106 provided by the mobile conveyor units 300. In this manner, the conveyor system 100 is extended. By extending the fixed conveyor 200 coincidentally with the extension of the conveyor system 100, the downtime of the conveyor system 100 may be reduced. In some embodiments, the mobile conveyor units are provided and replaced based on their operating time, for example, to optimize maintenance and operational life. For example, where a first mobile conveyor is provided and then a second mobile conveyor, subsequent extension of the system after replacement by extension of the fixed conveyor may be effected by providing the second mobile conveyor and then the first mobile conveyor.

[0091] In extending the fixed conveyor 200, a belt 206 of the fixed conveyor 200 is cut, extended and spliced, and additional modules, such as span modules 230, intermediate drive modules 220, intermediate loading modules 260, or some combination thereof, are added to the fixed conveyor 200. In some embodiments, the fixed conveyor 200 is extended only after a predetermined number of mobile conveyor units have been added to the conveyor system 100. As shown in Figures 4A-4E, in some embodiments, the predetermined number of mobile conveyor units 300 is three. As shown in Figures 5A to 5G, in other embodiments, the predetermined number of mobile conveyor units 300 is five. In some embodiments, the modules to be added to the fixed conveyor 200 are staged, and additional belt lengths are loaded (such as from belt reels) prior to any shutdown of the conveyor system 100 for extending the fixed conveyor 200. In some embodiments, a belt splice may take less than about 72 hours. In some embodiments, splicing the belt includes using a preformed splice kit. Although such kits for very wide belts may be difficult to transport, their use may significantly reduce the time required for splicing the belt. In some embodiments, splicing the belt includes using a“piano wire” method for stripping steel cables to recue time required for buffing the cables during a splice. In some embodiments, if the final take-up position can be determined, multiple belt splices may be performed concurrently. This approach may require duplication of equipment and resources.

[0092] The extension of the fixed conveyor 200 on a bench-by-bench basis is an alternative to providing multiple mobile conveyor units 300. However, repeated splicing may subject the belt 206 to additional wear and tear, resulting in more frequent servicing and risk of belt failure due to degradation of the belt’s tension rating. Further, the extension of the fixed conveyor 200 may result in more operational downtime of the conveyor system 100, and requires more personnel as compared to providing mobile conveyor units 300. As such, it may not be economically or logisti cally feasible to more frequently extend the fixed conveyor 200 on a bench-by-bench basis. In some embodiments, the fixed conveyor 200 is extended only after a predetermined number of extensions through the addition of mobile conveyor units 300.

[0093] In some embodiments, the length of the extension is determined based on the increase of the operating capacity due to the operation of an additional motor 212. In some embodiments, at least one motor 212 of the fixed conveyor 200, which was not operating to drive the fixed conveyor 200 during transport of material prior to the extension of the fixed conveyor 200, is activated to drive the fixed conveyor after the extension of fixed conveyor 200. In some embodiments, the extension of the fixed conveyor 200 includes adding a motor 212 (such as by the addition of an intermediate drive module 220). The additional operation of each motor may provide capacity to extend the fixed conveyor by a certain amount. If the fixed conveyor is not extended by that amount, the drive may not be operating to its full capability and the fixed conveyor may therefore be overpowered for its task. By extending the fixed conveyor 200 only after the predetermined number of extensions through mobile conveyor unit addition has been reached, the excess capacity of the additional motor 212 may be reduced. In some embodiments, the full load full length power demand is about 80 to 85 percent of installed power. In some embodiments, each motor has a power rating of about 3 to about 9 MW, preferably about 7 MW. In some embodiments, the maximum length of the fixed conveyor 200 at 20% grade is about 400 m for one 7 MW motor, about 800 m for two 7 MW motors, and about 1250 m for three 7 MW motors. In some embodiments, the size of the motor is selected based on an characteristic of the mine, such as length of extension, ramp grade, bench height, number of benches an extension of the fixed conveyor is intended to span, or a combination thereof.

[0094] In some embodiments, the conveyor system includes additional fixed conveyors. The additional fixed conveyors may be desirable to extending the fixed conveyor in certain circumstances, for example, due to repeated belt splices that could reduce life of the belt of the fixed conveyor, due to all motors preinstalled on the fixed conveyor already being operational, reliability issues associated with an overextended conveyor, etc.

[0095] In some embodiments, the transporting of material obtained from the mine to the surface includes receiving the material onto the conveyor system 100 at at least one loading module. In some embodiments, the at least one loading module includes a tail loading module 250, one or more intermediate loading modules 260, or any combination thereof. When material is loaded at the tail loading module 250 and the intermediate loading modules 260, material may be removed from the formation 10 concurrently at one or more benches 16.

[0096] Material may be removed from the formation by explosive blasting, resulting in a distribution of large and small rocks. Large rocks may concentrate too much weight at a single location of the conveyor and/or may result in a hazards from rolling back down the conveyor system 100. In some embodiments, the material obtained from the mine to the surface is processed in a mobile crusher 500 before being received by the conveyor system 100. The crusher may reduce the size of the material obtained from the formation before it is loaded onto the conveyor system 100, thereby preventing excessively large material from being received by the conveyor system 100. [0097] Excessive surges in material flow fed onto a conveyor may subject the belt to additional wear and tear. In some embodiments, the conveyor system 100 receives material from a mobile surge loader. The mobile surge loader includes a receiving hopper and a feeder, such as an inclined apron feeder, to load material onto the conveyor system 100. The receiving hopper may be sized to have sufficient capacity to limit surges in material flow onto the conveyor system 100. The height of the conveyor system 100 may be higher than the mobile surge loader when the two are located on the same level. As such, in some embodiments, the mobile surge loader is located above the tail portion 104 of the conveyor system. In some embodiments, the mobile surge loader is located one bench above the tail portion 104.

[0098] In some embodiments, transporting of material obtained from the mine includes transportation of material obtained from multiple benches. In some of these embodiments, a branch conveyor transports material to the conveyor system 100 at an intermediate bench located above the tail. In these embodiments, the conveyor system includes an intermediate loading module for receiving the material from the branch conveyor.

[0099] In some embodiments, the conveyor system 100 has a design capacity of at least about 10,000 metric tonnes per hour (mtph) to about 25,000 mtph. In some embodiments, multiple conveyor systems may be used within a single mine.

[0100] In some embodiments, the modular nature of the conveyor system allows the work of engineering and construction to be reduced. For example, the modules may be fabricated at a location that is remote from the mine. In some embodiments, the fabrication includes the pre-installation of mechanical and/or electrical components. In some embodiments, the pre assembly of the conveyor is increased by providing a design with a high degree of design modularization (e.g. large sub-modules). In some embodiments, the pre-assembly of sub- modules is performed at a remote location. The modules are modular and scalable to fit with the optimised mine development sequence. Mine planning inputs may be independent of location. In some embodiments, the final assembly and installation of major components (such as the modules) is performed at the mine, with sub-modules being assembled off-site. The modules may be moved into position using trucks, self-propelled modular transporters or transport crawlers. Mining operations according to the present methods allow for semi- continuous and/or continuous extraction with high intensity. The method may use simplified bench-to-bench extraction rather than exploring and selecting locations in the formation based, for example, on concentration of a target in the formation. In some embodiments, the methods described herein allow for the significant reduction of personnel from the extraction process. [0101] Any document referred to in this specification is hereby expressly incorporated by reference in its entirety. To the extent that any terms or teachings of any referenced document conflicts with any term or teaching of the present specification, the term or teaching of the present specification shall govern.

[0102] Although the disclosure has been described and illustrated in exemplary forms with a certain degree of particularity, it is noted that the description and illustrations have been made by way of example only. Numerous alterations, modifications variations and changes in the details of construction and combination and arrangement of parts and steps may be made. Accordingly, such changes are intended to be included in the invention, the scope of which is defined by the claims.

[0103] Except to the extent explicitly stated or inherent within the processes described, including any optional steps or components thereof, no required order, sequence, or combination is intended or implied. As will be understood by those skilled in the relevant arts, with respect to both processes and any systems, devices, etc., described herein, a wide range of variations is possible, and even advantageous, in various circumstances, without departing from the scope of the invention, which is to be limited only by the claims.

Claims

1. A method for transporting material from a hard rock mine having a plurality of level benches extending sequentially downwards in a step-wise manner from a surface of the mine, the method comprising:

a) providing an extendable conveyor system having a head located at the surface of the mine and a tail located at a bench located downwards from the surface, the conveyor system including a fixed conveyor having a first end located at the surface and a second end located at least two benches beneath the surface, wherein the conveyor system is located on a ramp extending downwards from the surface and spanning the plurality of benches;

b) transporting material obtained from the bench having the tail of the conveyor system disposed thereon;

c) extending the tail of the conveyor system downward to a lower bench by moving a mobile conveyor via the ramp such that the mobile conveyor extends from the tail of the conveyor system to an extended tail disposed at the lower bench, the lower bench being one bench beneath the tail of the conveyor system prior to the extending;

d) transporting material obtained from the lower bench;

e) repeating steps c) and d) such that at least two mobile conveyors are provided; and

f) extending the tail of the conveyor system downwards a further bench by replacing the at least two mobile conveyors with an extension of the fixed conveyor such that the second end is located at the further bench;

g) transporting material obtained from the further bench; and

h) optionally repeating steps c) to g).

2. A method for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface of the mine, the method comprising:

providing an extendable conveyor system having a head disposed at or near the surface of the mine and a tail disposed at a first location located beneath the surface, the conveyor system defining a conveyance path that transports material from the tail to the head, the conveyor system including an extendable fixed conveyor having a first end disposed at the head and a second end disposed at a second location that is at or above the first location;

transporting material obtained from the mine to the surface using the conveyor system.

3. The method of claim 2, wherein the mine includes a ramp spanning from the surface of the mine down at least a portion of the plurality of benches, wherein at least a portion of the extendable conveyor system is located on the ramp.

4. The method of claim 3, wherein the first location is located on the ramp at one of the benches of the plurality of benches.

5. The method of claim 2, wherein the extendable conveyor system includes at least one mobile conveyor sequentially extending downwards from the second end of the fixed conveyor, the at least one mobile conveyor configured to extend the conveyance path from the second end to the tail.

6. The method of claim 2, further comprising extending the conveyance path of the extendable conveyor system downward to a third location, lower than the first location by providing a mobile conveyor at the tail, wherein the mobile conveyor defines an extended tail.

7. The method of claim 6 further comprising repeating the extending of the conveyance path of the conveyor system such that at least two mobile conveyors are provided.

8. The method of claim 3 or 4 further comprising removing at least one mobile conveyor and extending the fixed conveyor at the second end such that the conveyance path is the same length or longer than the conveyance path prior to the extending of the fixed conveyor.

9. The method of claim 8, wherein the extending of the fixed conveyor comprises the addition of one or more modules chosen from span modules, intermediate drive modules, intermediate loading modules, or any combination thereof.

10. The method of claim 8, wherein the number of removed mobile conveyors is based on an increase of capacity based on operation of an additional drive of the fixed conveyor.

11. The method of claim 2 further comprising providing a bench conveyor having a head disposed at a location from below the head to the tail of the conveyor system, the bench conveyor system extending along a bench for transporting material obtained from the bench to the conveyor system.

12. The method of claim 3 or 4 further comprising removing at least one mobile conveyor and providing a second fixed conveyor at the tail of the system such that the conveyance path is the same length or longer than the conveyance path prior to the providing of the second fixed conveyor.

13. An extendable conveyor system for transporting material from a hard rock mine having a plurality of benches extending downwards from a surface of the mine, the system comprising:

a head disposed at or near the surface of the mine and a tail disposed at a first location located beneath the surface, the conveyor system defining a conveyance path that transports material from the tail to the head; and

an extendable fixed conveyor having a first end disposed at the head and a second end disposed at a second location that is at or above the first location;

wherein when the second location is above the first location, system further comprises at least one mobile conveyor extending the conveyance path from the second end to the tail.

14. The system of claim 13, wherein the mine includes a ramp extending downwards from the surface, wherein the at least a portion of the extendable conveyor and at least a portion of the at least one mobile conveyor are located on the ramp, wherein the mobile conveyors are configured to extend the system down the ramp by one bench at a time.

15. The system of claim 13, wherein the fixed conveyor includes a plurality of motors, wherein at least a portion of the motors are configured for operation after an extension of the fixed conveyor.

16. The system of claim 15, wherein a length of an extension of the fixed conveyor is chosen based on the operating at least one additional motor of the plurality of motors.

17. The system of claim 15, wherein at least one motor of the plurality is chosen based on a length of an extension of the fixed conveyor by a predetermined number of benches.

18. The system of claim 13, further comprising a branch conveyor for transporting material along an intermediate bench to the fixed conveyor or one of the at least one mobile conveyors.

19. The system of claim 13, further comprising one or more additional fixed conveyors.