WO2023021460A1

WO2023021460A1 - Reef cutting machine

Info

Publication number: WO2023021460A1
Application number: PCT/IB2022/057746
Authority: WO
Inventors: Barend Jacobus Jordaan; Gerhard Pretorius; Nicolaas Bodenstein GOODWIN; Louis WANNENBURG; Izak Abram CROUS
Original assignee: African Rainbow Minerals Platinum Pty Ltd
Current assignee: African Rainbow Minerals Platinum Pty Ltd
Priority date: 2021-08-18
Filing date: 2022-08-18
Publication date: 2023-02-23
Anticipated expiration: 2024-02-18
Also published as: ZA202402171B; CN118355175A; CA3229446A1; EP4388176A1

Abstract

A reef cutting machine is disclosed, comprising a mobile carrier, typically mounted on tracks; a launching frame; and a cutter head assembly extending from the launching frame, towards and into the ore body to be cut to define a slot. The launching frame is angled/inclined relative to the carrier, to tilt the cutter head assembly to the correct angle to align the cutter head assembly with the angle of the ore body to be cut. In an embodiment, the launching frame (and cutter head assembly) is mounted transverse to the carrier, so that the launching frame and the cutter head assembly extends at right angles to the mobile carrier. In an embodiment, the cutter head assembly further comprises an extendible (relatively flat) cutter head with side stabilisers to engage the side walls of the slot being cut, with thrust cylinders being provided to move the cutter head away and towards the thrust body, in use.

Description

REEF CUTTING MACHINE

FIELD OF THE INVENTION

THIS invention relates to a reef cutting machine, also known as an ore cutting machine. At a high level, this machine is a mechanised, continuous underground mining/stoping machine for cutting or boring slots (also known as stopes) in a reef or ore body.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, a reef cutting machine comprises: a mobile carrier, typically mounted on tracks; a launching frame; and a cutter head assembly extending from the launching frame, towards and into the ore body to be cut to define a slot, with the launching frame being angled/inclined relative to the carrier, to tilt the cutter head assembly to the correct angle so as to align the cutter head assembly with the angle of the ore body to be cut.

In an embodiment, the launching frame (and cutter head assembly) is mounted transverse to the carrier, so that the launching frame and the cutter head assembly extends at right angles to the mobile carrier. In this regard, a first set of stabilising cylinders extend from (the side walls of) the mobile carrier and a second set of stabilising cylinders extend from the launching frame, to securely stabilise the cutting machine within a tunnel. In addition, lifting cylinders are provided to lift the launching frame relative to the mobile carrier, at the desired angle. In an embodiment, the cutter head assembly comprises a thrust body fitted with gripper pads on at least one side of the thrust body, but typically on both the upper and lower sides of the thrust body, to grip against the upper and lower walls of the slot being cut.

The cutter head assembly further comprises an extendible (relatively flat) cutter head with side stabilising cylinders to engage the side walls of the slot being cut, with thrust cylinders being provided to move the cutter head away and towards the thrust body, in use.

In an embodiment, the cutter head comprises a pair of counter rotating round cutter wheel assemblies. Each cutter wheel assembly in turn comprises two cutting drums, mounted directly opposite each other. Thus, in total there are four cutting drums, two drums per cutter wheel assembly. Each cutting drum is driven by a hydraulic motor mounted inside the cutting drum itself.

Each cutting drum carries a plurality of disc cutters, the disc cutters being angled on its axis, to accommodate steering.

The cutter head assembly further comprises a pair of top steering stabilising cylinders, to facilitate steering. The outer face of each cutting drum is fitted with centrifugal scrapers to scrape away chippings/cuttings toward a vacuum suction inlet located in the centre between the two cutter wheel assemblies.

In an embodiment, the counter rotating cutter wheel assemblies of the cutter head, and thus the cutting drums, are arranged horizontally and in line with the thrust body, which allows the machine to cut a rectangular slot in the ore body.

In an embodiment, the thrust body of the cutter head assembly includes a vacuum pipe having a front end, which defines the vacuum suction inlet proximate (and just behind) the centre between the two cutter wheel assemblies, and a swivel pipe end, which is connected, in use, to a plurality of drill-vacuum rods. The plurality of drillvacuum rods extends from the swivel pipe end of the vacuum pipe, within the thrust body of the cutter head assembly, to the launching frame, in which additional drillvacuum rods may be added, as the cutter head assembly progresses further and further away from the launching frame into the slot being cut.

This arrangement ultimately enables the rock chippings/cuttings entering from the front end of the vacuum pipe, which is arranged proximate and between the two pairs of counter rotating cutter wheel assemblies, to be vacuumed into a material collector that forms part of a larger modular reef cutting system, of which the reef cutting machine is one component. The overall objective of the modular reef cutting system is to facilitate transportation and setting up to minimise time between consecutive slots drilled; the modular reef cutting system is defined in more detail further below.

The drill-vacuum rods thus serve a dual function of facilitating vacuuming of the chippings/cuttings and providing structural support to hold the cutter head assembly in place in the slot in the event of a hydraulic or power failure. The drill-vacuum rods are fitted with an internal wear lining that can be changed as and when needed, thus extending the useful lifespan of each drill-vacuum rod.

In an embodiment, a separate umbilical cord or hose runs next to the plurality of drillvacuum rods, to facilitate remote operation. The cord is a continuous cord fed from a cable/hose reel arrangement forming part of the overall modular reef cutting system.

Various sensors are used to facilitate steering. These include Light Detection and Ranging (“LIDAR”) and optical sensors to detect visual differences between waste rock and the reef/ore rock and thus ensure maximum recovery of the reef/ore, whilst reducing the amount of waste rock mined. Ground penetrating radar is also used, to ensure that the mined-out stopes are parallel, ultimately ensuring maximum reef/ore recovery. Other sensors may be provided, including linear transducers, IMU (inertial measurement unit) that in turn typically comprises a gyroscope and accelerometer) and an inclinometer. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic perspective view of a modular reef cutting system according to the invention, and in particular, a mechanised, continuous underground reef cutting system for cutting or boring slots in a reef or ore body, the key component being a reef cutting machine comprising a mobile carrier mounted on tracks, a launching frame and a cutter head assembly extending from the launching frame via a plurality of drill-vacuum rods, towards and into the ore body to be cut, at an angle, to define a slot

Figure 2 shows a perspective view of the launching frame, after being tilted to the required angle, relative to the mobile carrier;

Figure 3 shows an internal view of the launching frame shown in Figure 2, with a top cover plate being removed for clarity;

Figure 4 shows a perspective view of the cutter head assembly shown in Figure 1 , the cutter head assembly comprising a pair of counter rotating round cutter wheel assemblies, each cutter wheel assembly in turn comprising two cutting drums, mounted directly opposite each other;

Figure 5 shows a top view and related side views of the cutter head assembly shown in Figure 4;

Figure 6 shows a cross-sectional top view of the cutter head assembly shown in Figures 4 and 5, taken along line E-E in Figure 5;

Figure 7 shows a cross-sectional side view of the cutter head assembly shown in Figures 4 and 5, taken along line F-F in Figure 5;

Figure 8 shows a cross-sectional side view of the cutter head assembly shown in Figures 4 and 5, taken along line D-D in Figure 5; Figure 9 shows a cross-sectional top perspective view of the left hand top and bottom cutting drums of the cutter head assembly shown in Figures 4 and 5, showing internal hydraulic motors, each being arranged to drive a cutting drum;

Figure 10 shows a perspective view and a cross-sectional side of a drill-vacuum rod used in the reef cutting machine of the present invention, with reference to Figure 1 ;

Figure 11 shows a bottom view of the cutter head assembly, showing a front end of a vacuum pipe, which defines a vacuum suction inlet proximate (and just behind) the centre between the two cutter wheel assemblies, and a swivel pipe end, which is connected, in use, to a plurality of drillvacuum rods;

Figure 12 shows another detailed schematic perspective view of the modular reef cutting system according to the invention, similar to Figure 1 , except that the launching frame and cutter head assembly are shown in a lowered, resting position;

Figure 13 shows a perspective view of another modular reef cutting system according to the invention, similar to Figure 12, with a slight variation in the arrangement of the individual components of the system;

Figure 14 shows a schematic perspective view of the modular reef cutting system shown in Figure 12, in position within an underground tunnel, ready to cut a slot into an adjacent ore body;

Figure 15 shows an example of a collaring cycle, to move the launching frame and cutter head assembly from a lowered, resting position (as shown in Figure 12) to an angled, extended position in which the cutter head assembly extends away from the launching frame; Figure 16 shows a side view of a tunnel envelope, in which the overall modular system can operate;

Figure 17 shows a schematic perspective view of the modular reef cutting system according to the invention shown in Figure 1 , with the addition of a separate umbilical cord or hose running alongside the plurality of drillvacuum rods, to facilitate remote operation;

Figure 18 shows the pair of counter rotating round cutter wheel assemblies of the cutter head assembly in use, and the sequential operation of a hydraulic gripper system and related thrust cylinders to allow the reef cutting machine to cut slots over a long distance;

Figure 19 shows the cutter head assembly cutting a slot into the adjacent ore body;

Figure 20 shows the cutter head assembly at the end of the excavation, after cutting a full-length slot into the ore body;

Figure 21 shows the cutter head assembly being retracted from the cut slot, one rod at a time;

Figure 22 shows a perspective view of the cut slot;

Figure 23 shows a series of cut slots, with the first two slots being fully filled with backfill material comprising of a mixture of tailings material and cement (“cemented backfill”) and the third slot being partially filled with cemented backfill;

Figure 24 shows the machine returning to cut slots being the previously cut (and now filled) slots; and

Figure 25 shows the result, namely an entire mined out ore body block, fully backfilled with cemented backfill. DETAILED DESCRIPTION OF THE DRAWINGS

At a high level, with reference to Figure 1 , this invention provides a modular reef cutting system 10 and, in particular, a mechanised, continuous underground reef cutting system 10 for cutting or boring slots in a reef or ore body. The overall system 10 will be described in more detail with reference to Figures 12 and 13, and the overall system 10, in use, to cut or bore slots 12 in a reef or ore body 14 will be described in more detail with reference to Figures 1 to 25.

The key component of the reef cutting system 10 is a reef cutting machine 20 comprising a mobile carrier 22 mounted on tracks 24, a launching frame 26 and a cutter head assembly 28 extending from the launching frame 26, via a plurality of drill-vacuum rods 30, towards and into the ore body 14 to be cut, at an angle, to define a slot 12.

In Figure 12, the cutter head assembly 28 of the reef cutting machine 20 are shown in a lowered, resting position. The launching frame 26 is omitted for clarity, but in this lowered, resting position, the cutter head assembly 28 is fully (or at least substantially) enclosed or accommodated within the launching frame 26 (as indicated in the first drawing of Figure 15). In use, as shown in Figures 1 and 2, the launching frame 26 and cutter head assembly 28 are tilted to the required angle, relative to the mobile carrier 22, using lifting cylinders 31. This is required so as to align the cutter head assembly 28 with the angle of the ore body 14 to be cut, and in particular to start the collaring cycle (as will be explained in more detail with reference to Figure 15).

The mobile carrier 22 is fitted with a rod or pipe loader 32, to facilitate the loading and sequential securing of the drill-vacuum rods 30, to define a string of drill-vacuum rods 30, as shown in Figure 1 for example.

As shown in Figure 1 , the launching frame 26 (and cutter head assembly 28) is mounted transverse to the carrier 22, so that the launching frame 26 and the cutter head assembly 28 extends at right angles to the mobile carrier 22 (and thus at right angles to the reef cutting system 10. In this regard, with reference to Figures 2 and 3 as well, a first set of stabilising cylinders 34 extend downwardly from the mobile carrier 22 and a second set of stabilising cylinders 36 (also known as stinging cylinders) extend from either side of the launching frame 26, to securely stabilise the cutting machine 20 within a tunnel 42 (as shown in Figures 14 and 16). The stabilising cylinders 36 extend on either side of thrust cylinders 43, as best shown in Figure 3.

As best shown in Figures 4 to 8, the cutter head assembly 28 comprises a relatively flat thrust body 44 fitted with hydraulic gripper pads 46 on at least one side of the thrust body 44, but typically on both the upper and lower sides of the thrust body 44, in order to grip against the upper and lower walls of the slot 12 being cut, as shown in Figures 20 and 21 , the operation of which will be described in more detail further below with reference to Figure 18.

The cutter head assembly 28 further comprises an extendible, and relatively flat, cutter head 48 with side stabilising cylinders 50 to engage the side walls of the slot 12 being cut. Thrust cylinders 52, 53 are mounted to the sides of the thrust body 44, and are arranged to move the cutter head 48 away and towards the thrust body 44, in use, as will be described in more detail further below with reference to Figure 18. The location and operation of the hydraulic gripper pad 46 and thrust cylinders 52, 53 on the cutter head assembly 28, in use, inside the slot 12, allows the reef cutting machine 20 to mine slots 12 over a long distance, thereby maximising productivity, as will be described in more detail below with reference to Figures 17 to 25. In addition, the thrust cylinder 52 is a relatively small thrust cylinder 52 whereas the thrust cylinder 53 is a relatively large thrust cylinder 53, which in turn assists in the steering of the cutter head assembly 28. The small thrust cylinder 52 refers to a relatively smaller diameter cylinder exerting a smaller force for a set pressure, when compared to the large thrust cylinder 53 which has a relatively larger diameter cylinder to exert a relatively larger force at a set pressure, thus assisting to counter the moment resulting from the weight of the front body and cutter head 48.

Figure 4 shows a plunger cylinder 54, to remove any debris blocking the vacuum pipe 108, as best shown in Figure 8. Hydraulic and electrical cables 56 connect the thrust body 44 with the cutter head 48, and are arranged in such a way to allow for the front cutter head 48 to extend and retract relative to the thrust body 44.

In an embodiment, the cutter head 48 comprises a pair of counter rotating (as indicated by arrows 59 in Figure 11 ) round cutter wheel assemblies 60, 62. Each cutter wheel assembly 60, 62 in turn comprises two cutting drums 64, 66 and 68, 70, respectively, mounted one on top of the other. Each cutting drum 64, 66, 68 and 70 carries a plurality of disc cutters 72. As best shown in Figures 8 and 9, the cutter drums’ 64, 66 and 68, 70 rotating axes are angled at a 0.3 ° angle relative to the vertical axis, and slopes backwards away from the face being cut, giving it a clearance at the back to ease with steering the cutter head 48.

In one version, as best shown in Figure 4, a vertical gauge protection cutter 73 may be used to assist with gauge protection of the cutter head 48 when turning.

Thus, in total there are four cutting drums 64, 66, 68 and 70, two drums 64, 66 and 68, 70, per cutter wheel assembly 60, 62, respectively. In addition, there is a central breaking pick 153 (shown in Figures 5 and 6), side breaking picks 157 (shown in Figures 5, 6 and 11 ) and a bottom breaking pick 110 (shown in Figure 8) to break the remainder of the gauge rock left.

As best shown in Figures 6, 7 and 9, each cutting drum 64, 66, 68 and 70 is driven by compact hydraulic motors 74, 75, 76, 77, 78, 79, 80 and 81 respectively i.e. there are two compact hydraulic motors per cutting drum. These compact hydraulic motors 74, 75, 76, 77, 78, 79, 80 and 81 in turn drive pinion gears 82, 83, 84, 85, 86, 87, 88 and 89, respectively. The hydraulic motors and pinion gears work in sets of two each to drive ring gears 176, 178, 180 and 182 which are connected to the cutting drums 64, 66, 68 and 70 themselves and all these components are mounted inside the cutting drums 64, 66, 68 and 70 to have the compact assembly required for the envelope that needs to be cut. This internal mounting of the hydraulic motors 74, 75, 76, 77, 78, 79, 80 and 81 inside their respective cutting drums 64, 66, 68 and 70 not only saves space, but it also allows a high gear reduction ratio to be achieved inside the related gearboxes that house the motors and gears. The hydraulic motors 74, 75, 76, 77, 78, 79, 80 and 81 inside the cutting drums 64, 66, 68 and 70 are used to provide the required rotational torque to the cutting drums 64, 66, 68 and 70, and allows for the high torque needed to cut hard rock.

The cutter head assembly 28 further comprises a pair of top steering stabilising cylinders 90, 92 and related steering cylinder brackets 94, 96 (as best shown in Figures 4, 5 and 6), to facilitate steering, and in particular to reduce the force required to steer the cutter head 48.

The outer face plates of each cutting drum 64, 66, 68 and 70 is fitted with centrifugal scrapers 98, 100, 102 and 104, respectively to scrape away chippings/cuttings towards a vacuum suction inlet 106 (best shown in Figure 8) located in the centre between the two cutter wheel assemblies 60, 62.

As is clear from the figures, the counter rotating cutter wheel assemblies 60, 62 of the cutter head 48, and thus the cutting drums 64, 66, 68 and 70 themselves, are arranged horizontally and in line with the thrust body 44, which allows the machine 20 to cut a rectangular slot 12 in the ore body 14. This arrangement results in several unique operational benefits, namely:

1 . Maximising the extraction of the high-grade ore/reef.

2. Maximising the grade of the ore/reef by minimising the dilution from the hanging wall and footwall rock formations.

3. Allowing the rock cutting to remain within one rock geology, thereby maximising cutting productivity.

In addition, the relatively large diameter of the cutting drums 64, 66, 68 and 70 allows for the fitment of disc cutters 72 which allows higher thrust to be applied to the cutter wheel assemblies 60, 62, thereby ensuring maximum rock penetration and cutting productivity.

As best shown in Figure 8, the thrust body 44 of the cutter head assembly 28 includes a vacuum pipe 108 with the bottom breaking pick 110, which defines the vacuum suction inlet 106 proximate (and just behind) the centre between the two cutter wheel assemblies 60, 62, and a swivel pipe end 112, which is connected, in use, to a plurality of drill-vacuum rods 30, of the type shown in Figure 10.

As indicated above, the plurality of drill-vacuum rods 30 extends from the swivel pipe end 112 of the vacuum pipe 108, within the thrust body 44 of the cutter head assembly 28, to the launching frame 26, in which additional drill-vacuum rods 30 may be added using the loader 32, as the cutter head assembly 28 progresses further and further away from the launching frame 26 into the slot 12 being cut. This is akin to a raise boring machine, to allow for modular connection and tightening of the drill-vacuum rods.

This arrangement ultimately enables the rock chippings/cuttings entering from the front end of the vacuum pipe 108, via the vacuum suction inlet 106, which is arranged proximate and between the two pairs of counter rotating cutter wheel assemblies 60, 62, to be vacuumed into a material collector 114, via a vacuum disposal pipe 117 that extends from within the thrust body 44 to the material collector 114, as shown in Figures 1 , 3 and 13. The material collector 114 forms part of the larger modular reef cutting system 10, of which the reef cutting machine 20 is one component. The overall objective of the modular reef cutting system 10 is to facilitate transportation and setting up to minimise time between consecutive slots 12 being cut; the modular reef cutting system 10 is defined in more detail further below.

The drill-vacuum rods 30 thus serve a dual function of facilitating vacuuming of the rock chippings/cuttings and providing structural support to hold the cutter head assembly 28 in place within the cut slot 12, in the event of a hydraulic or power failure. The structural nature of the drill-vacuum rods 30 also assists in allowing the cutter head assembly 28 to be withdrawn out of the cut slot 12, especially in the case of hole deformation or closing behind the cutter head assembly 28.

In one version, the drill-vacuum rod 30 has a length of approximately 2 metres, and includes threaded end connections 116, 118 and spanner flats 120 (to facilitate assembly), as best shown in Figure 10. The threaded end connections 116, 118 provides structural support, with a swivel connection being provided to enable the drill-vacuum rods 30 to be added and removed. The drill-vacuum rods 30 may be fitted with an internal wear lining 122 that can be changed as and when needed, thus extending the useful lifespan of each drill-vacuum rod 30.

Various sensors are used to facilitate steering. These include LIDAR and optical sensors 124 to detect visual differences between waste rock and the reef/ore rock and thus ensure maximum recovery of the reef/ore. Ground penetrating radar 126 is also used, to ensure that the mined-out stopes are parallel, ultimately ensuring maximum reef/ore recovery. Other sensors may be provided, including linear transducers, IMU (inertial measurement unit) that in turn typically comprises a gyroscope and accelerometer) and an inclinometer.

Turning back to Figure 1 , the overall modular reef cutting system 10 includes the reef cutting machine 20 described above, a cable/hose reel arrangement 130, a rod carrier 132 to carry the plurality of drill-vacuum rods 30 (that can provided a total length of approximately 100 metres), a vacuum power pack 134 and related material collector 114 to vacuum and then collect the chippings/cuttings, for subsequent removal, and related hydraulic and electrical packs 138. The modular nature of the overall reef cutting system 10 means that these components may be arranged in different ways.

In the schematic version shown in Figure 12, the sequence of components is the rod carrier 132, then the reef cutting machine 20, then the cable/hose reel arrangement 130, then the hydraulic and electrical packs 138, then the vacuum power pack 134 and related material collector 114. In this version, a collector truck 140 is provided, into which the chippings/cuttings may be dumped, for subsequent removal. As indicated above, in Figure 12, the launching frame 26 and cutter head assembly 28 of the reef cutting machine 20 are shown in a lowered, resting position.

In the version shown in Figure 13, the sequence of components is an electrical gully box 142, then the hydraulic pack 138, then the cable/hose reel arrangement 130, then the rod carrier 132, then the reef cutting machine 20, then the electrical pack 151 , then the vacuum power pack 134 and related material collector 114, and a filter box 136 between the vacuum power pack 134 and the material collector 114. In this version, an LHD (load, haul and dump) vehicle 144 is provided, to collect the chippings/cuttings, for subsequent removal.

In both cases, however, the objective is to provide a compact and modular reef cutting system 10, to facilitate the transportation of each individual component or module, one by one, down the mine. The components may then be set up inside the drive/tunnel 42, to enable the overall system 10 to be set up modularly. In this regard, a mobile hydraulic pack/drive unit (also known as motivator) may be used to transport and position each component within the drive/tunnel 42. Figure 14 shows a schematic perspective view of the modular reef cutting system 10 shown in Figure 12, in position within an underground/ tunnel 42, ready to cut a slot 12 into an adjacent ore body 14.

Once in position, a collaring cycle begins, as will now be described with reference to Figure 15. In a first step 146, the lifting cylinders 31 (shown in Figure 2) are actuated to tilt the cutter head assembly 28 to the required angle, relative to the mobile carrier 22, typically at an angle of between 10 and 25 degrees to align with the dip angle of the orebody. Although not shown, the first set of stabilising cylinders 34 would be extended downwardly to engage the floor of the tunnel 42. In a second step 148, the second set of stabilising cylinders 36 are actuated to extend from the launching frame 26, to abut against the side walls 150, 152 of the tunnel 42, of the type shown in Figure 16, to securely stabilise the cutting machine 20 within the tunnel 42. Next, in step 154, the cutter head assembly 28 is extended from the launching frame 26 using the thrust cylinders 43 of the launching frame 26 that are connected to a crosshead 155 (shown in Figure 3), which in turn is arranged to push against a rear face 29 (shown in Figure 11) of the thrust body 44. After a full stroke of the thrust cylinders 43, a first drill-vacuum rod 30 may be inserted and connected to the swivel pipe end 112 of the vacuum pipe 108 of the thrust body 44, in step 156, using the rod or pipe loader 32 (as also shown in Figure 3). The result is the cutter head assembly 28 extending at the correct angle relative to the launching frame 26.

In terms of envelope size and compactness, as shown in Figure 16, the machine 20 and each module of the overall system 10 is designed to fit into an envelope profile with a minimum height of 2.2 metres and a width of 5 metres. As shown in Figure 17, as the cutter head assembly 28 moves further away from the launching frame 26, additional drill-vacuum rods 30, retrieved from an adjacent rod carrier 132, are connected together, to define a string of drill-vacuum rods 30. This Figure 17 also shows a separate umbilical cord or hose 158 that extends through the launching frame 26, from an adjacent cable/hose reel arrangement 130, the cord 158 running alongside the string of drill-vacuum rods 30, to facilitate remote operation and provide hydraulic power to the cutter head 48.

The cord 158 is typically a continuous cord 158 fed from the cable/hose reel arrangement 130 forming part of the overall modular reef cutting system 10, to ultimately service the intended approximately 100 metre length of the cut slot 12. The structural and operational separation of the umbilical cord 158 and the plurality of drill-vacuum rods 30 allows for the modular rods 30 to connect and take up the umbilical cord 158, without human interaction.

Figure 18 shows the pair of counter rotating round cutter wheel assemblies 60, 62 of the cutter head assembly 28 in use, as indicated by arrows 160, 162, and the sequential operation of the hydraulic gripper pads 46 and related thrust cylinders 52, 53 to allow the reef cutting machine 20 to cut slots 12 over a long distance. In particular, at the start of the advance, the gripper pads 46 grip against the upper and lower walls of the slot 12 being cut, as shown by arrows 164 and arrow 166. Once secured, the thrust cylinders 52, 53 are actuated, as indicated by arrows 168 and arrow 170, to push the cutter head 48 forwardly and away from the thrust body 44, while the counter rotating round cutter wheel assemblies 60, 62 cut the slot 12. Once the stroke is complete, as shown by arrow 172, the gripper pads 46 are released, with the thrust body 44 and drill-vacuum rods 30 then advancing to rejoin the cutter head 48. This enables a new drill-vacuum rod 30 to be inserted at the bottom of the string, connected to the swivel pipe end 112 of the vacuum pipe 108, using the rod or pipe loader 32.

Figure 19 shows the cutter head assembly 28 cutting the slot 12 into the adjacent ore body 14, and Figure 20 shows the cutter head assembly 28 at the end of the excavation, after cutting a full-length slot 12 into the ore body 14. Once cut, as shown in Figure 21 , the cutter head assembly 28 is retracted from the cut slot 12, one rod 30 at a time, with Figure 22 showing a perspective view of the cut slot 12.

As shown in Figure 23, the system 10 and machine 20 then advances by around 3 metres. The cutting process is then repeated, to cut a second (and subsequent) slot/s 12, spaced apart from the previous slots 12, resulting in a series of cut slots 12. The slots 12 are then backfilled with cemented backfill 174. In this figure, the first two slots 12 are shown fully filled and the third slot 12 is shown partially filled with cemented backfill.

As shown in Figure 24, the system 10 and machine 20 then moves back to the beginning, to cut slots 12 into the ore body 14 between the previously cut (and now filled) slots 12.

Figure 25 shows the result, namely an entire mined out ore body 14 block, fully backfilled with cemented backfill.

The reef cutting machine 20 and overall system 10 is designed to be remotely operable. Initially, this would be done from a small distance away from the machine 20, but it is envisaged that this would then take place from a greater distance away from the machine 20 (a few hundred metres), but eventually from an underground or surface control room. The only envisaged human intervention would be for maintenance and repairs.

Claims

1 . A reef cutting machine comprising: a mobile carrier; a launching frame supported by the mobile carrier; and a cutter head assembly extending from the launching frame, towards and into an ore body to be cut to define a slot, with the launching frame being angled relative to the carrier, in use, to tilt the cutter head assembly to the correct angle so as to align the cutter head assembly with the angle of the ore body to be cut.

2. The reef cutting machine of claim 1 , wherein the launching frame and cutter head assembly is mounted transverse to the mobile carrier, so that the launching frame and the cutter head assembly extends substantially at right angles to the mobile carrier.

3. The reef cutting machine of claim 2, wherein lifting cylinders are provided to lift the launching frame relative to the mobile carrier to the desired angle for use.

4. The reef cutting machine of claim 2, wherein a first set of stabilising cylinders extend from the mobile carrier and a second set of stabilising cylinders extend from the launching frame, to securely stabilise the cutting machine within a tunnel.

5. The reef cutting machine of any one of the preceding claims, wherein the cutter head assembly comprises a thrust body fitted with gripper pads on at least one side of the thrust body, to grip against the walls of the slot being cut.

6. The reef cutting machine of any one of the preceding claims, wherein the cutter head assembly further comprises an extendible, relatively flat, cutter head with side stabilisers to engage the side walls of the slot being cut, with thrust cylinders being provided to move the cutter head away and towards the thrust body, in use.

7. The reef cutting machine of claim 6, wherein the cutter head comprises a pair of counter rotating round cutter wheel assemblies arranged side by side, with each cutter wheel assembly in turn comprising two cutting drums mounted one on top of the other.

8. The reef cutting machine of claim 7, wherein the counter rotating cutter wheel assemblies of the cutter head, and thus the cutting drums, are arranged horizontally and in line with the thrust body, which allows the machine to cut a rectangular slot in the ore body.

9. The reef cutting machine of claim 7, wherein each cutting drum is driven by a hydraulic motor mounted inside the cutting drum itself, with each cutting drum carrying a plurality of disc cutters, the disc cutters being angled on its axis, to accommodate steering.

10. The reef cutting machine of claim 9, wherein the cutter head assembly further comprises a pair of top steering stabilising cylinders, to facilitate steering.

11 . The reef cutting machine of any one of claims 7 to 10, wherein the outer face of each cutting drum is fitted with centrifugal scrapers to scrape away chippings/cuttings toward a vacuum suction inlet defined between the two cutter wheel assemblies.

12. The reef cutting machine of claim 11 , wherein the thrust body of the cutter head assembly includes a vacuum pipe having a front end, which defines the vacuum suction inlet proximate a central zone between the two cutter wheel assemblies, and a swivel pipe end, which is connected, in use, to a plurality of drill-vacuum rods. 18

13. The reef cutting machine of claim 12, wherein the plurality of drill-vacuum rods extend from the swivel pipe end of the vacuum pipe, within the thrust body of the cutter head assembly, to the launching frame, in which additional drill- vacuum rods can be added, as the cutter head assembly progresses further and further away from the launching frame into the slot being cut.

14. The reef cutting machine of claim 13, wherein, in use, the rock chippings/cuttings enter from the front end of the vacuum pipe, which is arranged proximate and between the two pairs of counter rotating cutter wheel assemblies, and then vacuumed into a material collector that forms part of a larger modular reef cutting system, of which the reef cutting machine is one component.

15. The reef cutting machine of claim 13, wherein the drill-vacuum rods serve a dual function of facilitating vacuuming of the chippings/cuttings and providing structural support to hold the cutter head assembly in place in the slot.