CA3231721A1 - A cutting head assembly - Google Patents

Abstract

A cutting head assembly for excavating rock fragments from a mine wall is disclosed. In an embodiment, the cutting head assembly comprises a primary breakage mechanism actuable to apply, to the mine wall, a breakage force for breaking rock fragments from the mine wall. A surface of the cutting head assembly catches the rock fragments broken from the mine wall and has one or more ports associated therewith. A secondary breakage mechanism is operatively associated with the surface and actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface so as to allow at least the reduced size rock fragments to pass through a respective port for transportation to downstream processing.

Description

A CUTTING HEAD ASSEMBLY
PRIORITY CLAIM
[0001] This international patent application claims priority from Australian Provisional Patent Application No. 2021902939 titled "A Cutting Head Assembly" filed on 10 September 2021, the contents of which are to be taken as incorporated herein by this reference.
TECHNICAL FIELD

[0002] The present disclosure relates to a cutting head assembly. In a particular form, the present disclosure relates to a cutting head assembly for excavating rock fragments from a mine wall.
BACKGROUND

[0003] Many existing mineral deposits are not mined due to environmental constraints, low tonnages imposing financial constraints, complex geologies comprising hard rock, or a combination of one or more of these factors. In some cases, these mineral deposits are often too small to support or even attract the typical capital expenditure required to extract the ore bodies that may be present with conventional mining methods, such as open pit and underground mining methods. Due to the environmental impact and capital requirements of mining projects involving these mining methods, these projects are not always environmentally and economically feasible and, billions to trillions of dollars' worth of existing mineral deposits have been left in the ground.

[0004] Open pit and underground mining of hard rock typically uses one of either explosive excavation or mechanical rock fragmentation excavation.

[0005] Explosive excavation entails drilling a pattern of holes of relatively small diameter over an area of a rock body being excavated, and loading those holes with explosive charges. Once loaded, the explosive charges are then detonated in a sequence intended to fragment a required volume of rock for subsequent removal by suitable loading and transport equipment. This process is repeated cyclically until the required excavation is complete. The cyclical nature of explosive excavation and the violent nature of the rock fragmentation have, to date, presented difficulties to automating the explosive process and complicated downstream processing due to the unpredictable size distribution of the resultant rock fragments requiring re-handling.

[0006] Mechanical rock fragmentation excavation, such as excavation which involves rolling edge-type disc cutter technology, eliminates the use of explosives for excavation. Whilst this technology has facilitated automation of the excavation process to some extent, rolling edge-type disc cutters require the application of very large forces to crush and fragment the rock under excavation. In some applications, multiple cutters are arranged to traverse the rock in closely spaced parallel paths, resulting in a cutting machinery arrangement having significant weight and electrical power requirements. For example, such machinery may weigh in the order of thousands of tons and require thousands of kilowatts for operation. Such weight and power requirements impose significant operational drawbacks. Another drawback of rolling edge-type disc cutter technology is that it may involve using multiple rolling edge-type cutters in an array, thus forming a larger cutting profile. Such an arrangement creates more waste during excavation due to a larger contact face. As such, this technology is typically only economically feasible on large mining projects with large mineral deposits.

[0007] In addition to the above, a drawback common to both open pit and underground mining is that they both have a large environmental footprint and a detrimental impact on the existing ecological system and landscape. For example, open pit mining in particular, requires one or more tailings dams to store by products of mining operations and is usually highly toxic and, in some instances, radioactive.

[0008] Thus there is a requirement for a mining solution for smaller scale mineral deposits which provides one or more of a reduced environmental footprint, improved downstream rock fragment processing, or improved efficiency for mining hard rock whilst reducing waste.

[0009] It is against this background and the problems and difficulties associated therewith, that the present invention has been developed.
SUMMARY
[00 10] Embodiments of the present disclosure relate to a cutting head which excavates and mechanically processes rock fragments from, for example, a mine wall so as to provide, for downstream processing, processed rock fragments having at least one geometric dimension which depend on the mechanical processing of the excavated rock fragments by the cutting head. Before continuing further, it is to be noted that although the description which follows relates to an embodiment which is configured to break rock fragments from a mine wall, it will appreciated that other embodiments may be configured for breaking rock fragments in other applications, such as horizontal direction tunnelling and trench cutting.
[0011] In certain embodiments, the cutting head is configured to break rock fragments from the mine wall and mechanically process the resultant rock fragments prior to a downstream processing stage to provide, for the downstream processing stage, rock fragments having at least one geometric dimension which is dependent on the mechanical processing. In certain embodiments, the mechanical processing involves reducing the size of rock fragments having a geometric dimension which obstructs them from passing through one or more ports of the cutting head. Once so reduced in size, processed rock fragments are then able to proceed, via a respective port, to the downstream processing stage.
[0012] According to a first aspect of the present disclosure, there is provided a cutting head assembly for excavating rock fragments from a mine wall, the cutting head assembly comprising:
a primary breakage mechanism actuable to apply, to the mine wall, a breakage force for breaking rock fragments from the mine wall;
a surface for catching the rock fragments broken from the mine wall, the surface having one or more ports associated therewith; and a secondary breakage mechanism operatively associated with the surface, the secondary breakage mechanism actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface so as to allow at least the reduced size rock fragments to pass through a respective ports for transportation to downstream processing.
[0013] In one form, the primary breakage mechanism comprises one or more primary cutters for breaking rock fragments from the mine wall.
[0014] In one form, the or each of the primary cutters comprise one or more cutting elements for excavating rock fragments from the mine wall. In certain embodiments, the or each cutting element provides a depth of cut in the mine wall in the range of 30mm to 80mm.
[0015] In one form, the breakage force is a percussive force applied by actuation of the primary breakage mechanism. In certain embodiments, actuation of the primary breakage mechanism to provide the percussive force involves a reciprocating action of the one or more primary cutters.
[0016] In certain embodiments, the percussive force of the primary breakage mechanism provides between 50J and 1000J of impact energy at 20 to 400Hz. In a particular embodiment, the primary breakage mechanism provides between 300J and 400J of impact energy at a frequency of between 60 and 70Hz.
[0017] The secondary breakage mechanism may comprise one or more secondary cutters. For example, in some embodiments, the or each secondary cutter comprises one or more blades for reducing the size of at least some of the rock fragments caught by the surface. In one form, the or each blade is proximally associated with the or each port. In certain embodiments it is possible that the proximally association is such that a blade co-operates with a respective at least one port as to provide the secondary breakage mechanism. For example, in some embodiments, the or each blade co-operates with a respective at least one port to provide operatively associated shearing surfaces for providing the secondary breakage mechanism. Actuation of the secondary breakage mechanism may involve moving the or each blade so as to shear at least some of the rock fragments located within a port to thereby reduce the size of that rock fragment and thus allow the reduced size rock fragments to move off of the surface through the proximally associated port.
[0018] In certain embodiments, during actuation of the secondary breakage mechanism, the or each blade contacts with and sweeps across a portion of the surface so as stir the rock fragments caught by the surface after operation of the primary breakage mechanism. In certain embodiments, the stirring involves the one or more blades pushing or guiding at least some of the rock fragments towards respective port or ports proximally associated with the respective blade.
[0019] In one form, the or each secondary cutter of the secondary breakage mechanism is associated with at least one of the primary cutters of the primary breakage mechanism.
[0020] In one form, the primary breakage mechanism is actuated by a primary actuator and the secondary breakage mechanism is actuated by a secondary actuator.
[0021] In one form, the primary and secondary actuators are independently operable.
[0022] In one form, the primary and secondary actuators are hydraulic actuators.
[0023] In one form, the secondary actuator actuates the secondary breakage mechanism subsequent to the primary actuator actuating the primary breakage mechanism.
[0024] In one form, the cutting head assembly further comprises a fluid passageway located within a housing. In certain embodiments, the fluid passageway extends between the or each port and an outlet to allow fluid communication therebetween of rock fragments which have moved from the surface via a port. In certain embodiments, the rock fragments communicated between the or each port and the outlet via the fluid passageway includes rock fragments which have been processed, and thus reduced in size, by the secondary breakage mechanism so as to enable them to pass through a respective port, and rock fragments not requiring a reduction in size to pass through a respective port.
[0025] In one form, the fluid communication of the rock fragments via the fluid passageway involves the application of a negative pressure or a suction pressure.

[0026] In one form, the outlet is proximal to a drive gear located on or within the housing. In certain embodiments, the drive gear connects to a pump, such as a suction pump, of a miner body to generate a negative or suction pressure sufficient to transport the rock fragments, which have passed through the or each port, to the outlet and subsequently to the miner body. In certain embodiments, the drive gear is located on a top of the housing.
[0027] In one form, the drive gear engages with a connecting gear of the miner body so as to connect the cutting head assembly to a mining system via the miner body.
[0028] In certain embodiments, the drive gear comprises a swing gear capable of rotating the cutting head assembly about a rotational axis of the connecting gear of the miner body. For example, in some embodiments, the swing gear is capable of rotating the cutting head assembly up to 190 degrees about the rotational axis of the connecting gear. In certain embodiments, the drive gear provides a feed force to, and controls the width of, an excavated face.
[0029] In certain embodiments, steering plates direct a reactive force of the swing motor onto the cutting face with the rock face "in front" of the respective steering plate absorbing that force.
[0030] In one form, the drive gear transmits a feed force from the miner body to the cutting head assembly. The feed force may be proportional to an applied weight of the miner body. In one form, the feed force is output at the primary breakage mechanism and subsequently applied to the mine wall. In certain embodiments, the feed force thus originates from a drive gear.
[0031] In certain embodiments, the miner body controls the depth of cut via an adjustable support mechanism coupled to or otherwise connected with the base carrier. The adjustable support mechanism may include, for example, a cable arrangement.
[0032] In one form, a combination of the feed force and the percussive force of the primary breakage mechanism permits the cutting head assembly to engage with, and maintain engagement with, the mine wall.
[0033] In one form, the feed force transmitted from the miner body to the cutting head assembly may be communicated as a force of up to 20 tonnes at the primary breakage mechanism.
[0034] In one form, the housing of the cutting head assembly is a sealed arrangement such that the cutting head assembly is operable when submerged in a fluid.

[0035] In one form, the mine wall fails in tension when the primary breakage mechanism is actuated to apply the breakage force to the mine wall.
[0036] In one form, the or each cutting element is a cutting insert, such as a Polycrystalline Diamond (PCD) insert.
[0037] In one form, the or each primary cutter is removably securable to the primary breakage mechanism. The size, shape and metallurgy of the or each primary cutter will vary according to rock type. It is possible that custom sized inserts will be required to suit certain ground conditions.
One example of a suitable material is tungsten carbide.
[0038] In one form, the or each primary cutter is removably securable from the primary breakage mechanism by a retaining mechanism.
[0039] In one form, the reduced size rock fragments are sufficiently small in size so as to be easily transported and processed.
[0040] In one form, the reduced size rock fragments have at least one geometric dimension of a predictable size as a result of the actuation of the secondary breakage mechanism.
[0041] In one form, the predictable fragment size of the reduced sized rock fragments are sized and shaped to be transported through the one or more ports to the outlet.
[0042] In one form, the cutting head assembly further comprises a control system, wherein the control system actuates and monitors the primary and secondary actuators of the primary and secondary breakage mechanisms. The control system may comprise, for example, a remote control interface which supports remote monitoring and control of the primary and secondary actuators of the primary and secondary breakage mechanisms, at the least.
[0043] According to a second aspect of the present disclosure, there is provided a cutting head assembly for excavating rock fragments from a mine wall, the cutting head assembly comprising:
a primary breakage mechanism actuable to apply, to the mine wall, a breakage force for breaking rock fragments from the mine wall;
a housing comprising a fluid passageway and a surface for catching the rock fragments broken from the mine wall, the surface having one or more ports associated therewith, wherein the fluid passageway extends between the one or more ports and an outlet;
a secondary breakage mechanism operatively associated with the surface and proximal to the one or more ports, the secondary breakage mechanism actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface so as to allow at least the reduced size rock fragments to move off of the surface through the one or more ports; and wherein, in use, the secondary breakage mechanism actuates subsequent to the primary breakage mechanism and a suction pressure applied to the outlet transports the reduced sized rock fragments via the one or more ports to the outlet for downstream processing.
[0044] According to a further aspect of the present disclosure, there is provided a cutting head assembly for excavating rock fragments from a mine wall, the cutting head assembly comprising:
a housing comprising one or more ports in fluid communication via a fluid passageway with an outlet and a surface, wherein the surface is configured for catching rock fragments from the mine wall;
a primary breakage mechanism comprising a shank and a head comprising a cutting element, wherein the cutting element engages the mine wall;
a primary actuator coupled to the housing, wherein the primary actuator comprises an annular body for receiving at least a portion of the shank therein;
a secondary breakage mechanism comprising a secondary cutter coupled to a secondary actuator mounted on the housing; and wherein, in use, the primary actuator transmits a percussive force to reciprocate the primary breakage mechanism to break rock fragments from the mine wall and the secondary actuator transmits a shearing force to oscillate the secondary breakage mechanism to shear the resultant rock fragments caught by the surface and received by the one or more ports so as to reduce the size of at least some of the rock fragments and move them off of the surface and out the outlet for downstream processing.
BRIEF DESCRIPTION OF DRAWINGS
[0045] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:
[0046] Figure 1 is a perspective view of a cutting head assembly according to an embodiment;
[0047] Figure 2 is a side cross-sectional view of the cutting head assembly of Figure 1;
[0048] Figure 3 is a bottom view of the cutting head assembly of Figures 1 and 2;
[0049] Figure 4 is a schematic view of a primary breakage mechanism according to an embodiment;

[0050] Figure 5 is a front view of the primary breakage mechanism of Figure 4;
[0051] Figure 6 is a side view of the primary breakage mechanism of Figures 4 and 5;
[0052] Figure 7 is a perspective detail view of a secondary breakage mechanism of the cutting head assembly;
[0053] Figure 8 is a perspective detail view of the secondary breakage mechanism of Figure 7 illustrating one or more ports and an excavated rock fragment;
[0054] Figure 9 is a side sectional view detailing a port, a fluid passageway, the primary and secondary breakage mechanisms of the cutting head assembly;
[0055] Figure 10 is a detailed view of the primary breakage mechanism engaging a mine wall;
[0056] Figure 11 is a perspective view of a cutting head assembly according to an alternative embodiment;
[0057] Figure 12 is a perspective view of a mining system comprising a miner body and the cutting head assembly according to an embodiment;
[0058] Figure 13 is a perspective alternate view of the mining system of Figure 12 illustrating the mining system, the miner body and the cutting head assembly;
[0059] Figure 14 is a perspective view detailing the mining system of Figures 12 and 13;
[0060] Figure 15 is a schematic view illustrating the miner body and the cutting head assembly in operation;
[0061] Figure 16 is a perspective view of the miner body of Figure 15;
[0062] Figure 17 is a side detail view of a cutting head assembly, according to certain embodiments, illustrating a primary breakage mechanism actuating to apply to a mine wall a breakage force for breaking rock fragments from the mine wall;
[0063] Figure 18 is a side sectional view of the cutting head assembly of Figure 17, illustrating a surface catching the rock fragments broken from the mine wall; and [0064] Figure 19 is a side sectional view of the cutting head assembly of Figure 18, illustrating a secondary breakage mechanism actuating to apply a force for reducing the size f at least some of the rock fragments caught by the surface.
[0065] In the following description, like reference characters designate like or corresponding parts throughout the figures.
DESCRIPTION OF EMBODIMENTS
[0066] Referring to any one of Figures 1 to 10, there is illustrated a cutting head assembly (100) according to an embodiment of the present disclosure, for excavating rock fragments from a mine wall.
[0067] In the present case, the cutting head assembly (100) engages a mine wall (1000, ref. Figure

10) to cause a primary mode of failure of the mine wall (1000) due to tension resultant of percussive forces generated by the cutting head assembly (100). Using a percussive force to generate tension allows the cutting head assembly (100) to excavate a mine wall (1000) comprising rock which is susceptible to breaking into rock fragments under tensile failure. In this respect, certain embodiments of the present disclosure involve transmitting energy into the rock as wave energy which causes tensional spalling and explosive rock failure. An advantage of this approach is that it allows for improved control of energy projection into rock compared to approaches which involve drilling and blasting.
[0068] In the illustrated embodiment, and with reference initially to Figure 1, a cutting head assembly (100) according to one embodiment comprises a primary breakage mechanism (10) actuable to apply, to the mine wall (1000), a breakage force for breaking rock fragments from the mine wall (1000). The depicted cutting head assembly (100) also comprises a surface (20) for catching the rock fragments broken from the mine wall (1000) by primary breakage mechanism (10), the surface (20) itself having one or more ports (21) associated therewith. The function of, and interaction between, the surface (20) and the ports (21) of the cutting head assembly (100) will be described in more detail below.
[0069] The cutting head assembly (100) additionally comprises a secondary breakage mechanism (30) which is operatively associated with the surface (20). As will be described in more detail below, in use the secondary breakage mechanism (30) is actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface (20) so as to allow at least the reduced size rock fragments to move off of the surface (20) through the one or more ports (21) for downstream processing.

[0070] In embodiments, the surface (20) of the cutting head assembly (100) catches the rock fragments broken, resultant of the breakage force applied by the primary breakage mechanism (10) from the mine wall (1000). The surface (20) shown here comprises a substantially flat surface.
However, it will be appreciated that the surface (20) may have any suitable configuration or form.
Examples of suitable configurations and/or forms include a surface of any one of a "tray", "platform", "ledge", "catch", "trap" or the like which is configured to function so as to catch the rock fragments broken as a result of the breakage force applied by the primary breakage mechanism (10).
[0071] Referring now to Figure 7 and Figure 8, in the present case the one or more ports (21) are sized and shaped so as to permit at least the reduced size rock fragments to pass therethrough. In this way, the one or more ports (21) advantageously ensure that only rock fragments having at least one geometric dimension which is less than a certain size are passed via a port (21) for downstream processing, noting that it is possible that not all rock fragments caught by the surface will require a size reduction in order to pass through a port (21) since some of the rock fragments caught by the surface (20) may be able to pass through a port (21) without requiring a size reduction.
Furthermore, it is also possible that rock fragments caught by the surface (20) which do not require a size reduction in order to pass through a port (21) will nevertheless be reduced in size by the secondary breakage mechanism (30).
[0072] Before proceeding further, it is to be noted that throughout this specification reference will be made to rock fragments which are reduced in size by the secondary breakage mechanism (30).
It will be appreciated that, in the context of this specification, a rock fragment may be reduced in size by any suitable secondary breakage mechanism (30).
[0073] In certain embodiments, the reduction in size of an "original" rock fragment involves the use of a secondary breakage mechanism (30) which applies a shearing force to the "original" rock fragment so as to "cut" the original rock fragment into two or more smaller rock fragments of a reduced size compared to the "original" rock fragment. In other embodiments, the secondary breakage mechanism (30) may involve a crushing pulverising, or impact type force which breaks the original rock fragment into two or more smaller rock fragments of a reduced size compared to the "original" rock.
[0074] In still other embodiments, a pressurised jet of gas or fluid may be used to erode or cut an original rock fragment into two or more smaller rock fragments. In certain embodiments, the secondary breakage mechanism (30) may involve a combination of forces generated by different means.

11 [0075] In embodiments, the size and shape of the one or more ports (21) may be configured to allow rock fragments which are sufficiently small in size to be easily transported and processed downstream. In this way, the size and shape of the one or more ports (21) enables the rock fragments which pass through a port (21) to have at least one geometric dimension of a predictable size and thus to provide rock fragments having a predictable fragment size for at least that geometric dimension, with the predictable fragment size being one whereby the rock fragments have a size and shape which permits them to pass through the one or more ports (21).
[0076] As shown in Figures 3 to 6, in the present case the primary breakage mechanism (10) comprises one or more primary cutters (11) for breaking rock fragments from the mine wall (1000).
In the present case, each primary cutter (11) is positioned to engage the mine wall (1000) when the primary breakage mechanism (10) is actuated to apply the primary breakage force to break rock fragments from the mine wall (1000).
[0077] In certain embodiments, the or each primary cutter (11) may be manufactured of a sufficiently hardened material comprising high tensile strength, capable of applying large tensile forces in use to the mine wall (1000).
[0078] As shown in Figure 4, the or each primary cutter (11) comprises one or more cutting elements (12) for excavating the rock fragments from the mine wall (1000). As shown in Figure 10, the one or more cutting elements (12) of the or each primary cutter (11) engage the mine wall (1000) when the primary breakage mechanism (10) is actuated to apply the breakage force.
[0079] The depicted one or more cutting elements (12) are positioned and arranged to engage the mine wall (1000) and excavate the mine wall (1000) by application of the breakage force on actuation of the primary breakage mechanism (10). In the present case, the one or more cutting elements (12) are selected to cause a failure of the mine wall (1000), and its geology, via tensile failure of the mine wall (1000). In this respect, hard rock is known to have a high compressive strength. However, the tensile strength of hard rock is typically 10% of the compressive strength.
Given this, the primary breakage mechanism (10), and subsequently the or each of the primary cutters (11) and the one or more cutting elements (12), are selected to exploit this weakness of hard rock. That is to say, in embodiments, the primary breakage mechanism (10) and subsequently the or each of the primary cutters (11) and the one or more cutting elements (12) are manufactured and designed so as to advantageously apply the breakage force to the mine wall (1000) such that the broken rock fragments are resultant of tensile failure of the mine wall (1000). Tensile failure of hard rock typically results from tension cracks forming at a point of contact between either one of the or each primary cutter (11) or the one or more cutting elements (12) and the mine wall (1000).

12 [0080] In embodiments, the primary cutters (11) and/or the one or more cutting elements (12) are manufactured from a material or materials according to the geology and rock expected to be excavated in the mine wall (1000) by the cutting head assembly (100). Suitable materials would be well understood by a person skilled in the art.
[0081] In certain embodiments, the one or more cutting elements (12) provide up to an 80mm "depth of cut" in the mine wall (1000), with the actual depth depending on various factors, including the geology of the rock. Furthermore, the one or more cutting elements (12) may be designed and/or arranged to provide an "angle of attack", being the angle at which the cutting element (12) engages the mine wall (100). The combination of the angle of attack and percussive force results in lower temperatures generated at the one or more cutting elements (12) compared to conventional drilling based techniques, advantageously improving the life of the cutting elements (12). In contradistinction, the use of conventional percussion or tri-cone/drag bit drilling applications results in the generation of high temperatures, resulting in de-lamination of cutting elements used in these applications.
[0082] Continuing now with reference to Figure 4, in certain embodiments, the one or more cutting elements (12) are Polycrystalline Diamond (PCD) inserts, as are well known for their use in mining and drilling operations, particularly in those applications involving hard rock or ore bodies.
In this way, the one or more cutting elements (12) and their associated angle of attack, effectively excavates the mine wall (1000) in a manner such as to "plane off' the rock fragments, as opposed to drilling or boring into the mine wall (1000), using the percussive force applied by the primary breakage mechanism (10) to cause a tensile failure of the mine wall (1000).
[0083] Suitable alternative cutting elements (12) such as tungsten carbide inserts, titanium carbide inserts and others may also be selected for use, and the selection of cutting elements (12) would be well within the knowledge of a skilled person. The person skilled in the art will also appreciate that the selection of cutting elements (12) involves consideration of the friction forces and temperatures during excavation/engagement of the mine wall at high contact pressures, commonly greater than 2GPa pressure waves (as often encountered in percussion drilling).
[0084] In the embodiment of the cutting head (100) illustrated in any one of Figures 1 to 11, the breakage force is a percussive force applied by actuation of the primary breakage mechanism (10).
In certain embodiments, the percussive force of applied by the primary breakage mechanism (10) provides up to 1000J of impact energy at 20 to 400Hz. However, it will of course be appreciated that the impact energy and frequency of the percussive force applied by the primary breakage mechanism (10) may vary according to the geology and rock expected to be excavated in the mine

13 wall (1000) by the cutting head assembly (100). Suitable impact energy and frequency parameters would be well within the knowledge of a skilled person.
[0085] In terms of the effect of the percussive force applied by the primary breakage mechanism (10), the primary breakage mechanism (10), when actuated, causes a pressure wave at the speed of sound to penetrate through the mine wall (1000) (via reciprocating motion) when engaged by the or each primary cutters (11), and thus by the one or more cutting elements (12).
Engagement of cutting elements (12) with the mine wall (1000) applies sufficient percussive force such that the mine wall (1000) fails in tension. In one embodiment, in which the cutting elements (12) have an µ`angle of attack", the combination of the angle of attack and the percussive force applied by actuation of the primary breakage mechanism effectively excavates the mine wall (1000) by causing rock fragmentation.
[0086] In certain embodiments, and as is illustrated in Figures 3 to 4 and 6, the primary breakage mechanism (10) comprises a shank (14) and a head (15), the head (15) being at one end of the shank (14). The head (15) comprises the primary cutter (11), which itself comprises or supports the one or more cutting elements (12). In these embodiments, the one or more cutting elements (12) are positioned and/or arranged to engage the mine wall (1000) to impart the breakage force thereupon.
[0087] With reference now to Figure 4, in the illustrated embodiment the shank

(14) comprises a receptacle (16) which is sized and shaped to receive a portion of a retaining mechanism (13) therein (ref Figure 3). In this embodiment, the or each primary cutter (11) is removably securable to the primary breakage mechanism (10). In a particular embodiment, and as is illustrated in Figure 3, the retaining mechanism (13) comprises a retaining pin which removably secures the or each primary cutter (11) to the primary breakage mechanism (10). In the present case, the or each primary cutter (11) may be removed from the primary breakage mechanism (10) by removing the retaining pin (13), a portion of which is received within the receptacle (16) of the shank (14). In this way, the or each primary cutter (11), and subsequently the one or more cutting elements (12), may be easily removed from the primary breakage mechanism (10) after use for repair, inspection or replacement with another primary cutter (11).
[0088] In one embodiment, and referring now to any one of Figures 1 to 2 and 7 to 9, the secondary breakage mechanism (30) comprises one or more secondary cutters (31). The or each secondary cutter (31) may be designed such that on actuation of the secondary breakage mechanism (30), the or each secondary cutter (31) applies the force for reducing the size of at least some of the rock fragments caught by the surface (20) to allow at least the reduced size rock fragments to move off the surface (20) through the one or more ports (21).

[0089] In the above embodiment, and referring now to Figures 7 and 8 in particular, the or each secondary cutter (31) comprises one or more surfaces or edges for reducing the size of at least some of the rock fragments caught by the surface (20). The one or more surfaces or edges may be designed to shear the rock fragments broken from the mine wall (1000) caught on the surface (20) and reduce the size of at least some of those rock fragments on actuation of the secondary breakage mechanism (30).
[0090] In the present case, the or each secondary cutter (31) is proximally associated with a respective one or more ports (21). In this way, actuation of the secondary breakage mechanism (30) involves moving the or each secondary cutter (31) so as to shear rock fragments at least partially located within a port (21) associated with the surface (20) to thereby allow at least reduced size rock fragments to pass through the proximally associated port (21). In other words, in embodiments, rock fragments caught by the surface which would otherwise not be able to move off the surface (20) via a port (21), as a result of their size relative to the port (21), may be effectively reduced in size by the secondary cutter (31), resulting in one more rock fragments of a reduced size passing through the port (21) for downstream processing.
[0091] In certain embodiments, and as is illustrated in any one of Figures 1, 2, 7 and 8, the or each secondary cutter (31) of the secondary breakage mechanism (30) is associated with at least one of the primary cutters (11) of the primary breakage mechanism (10). In this way, for every secondary cutter (31) of the secondary breakage mechanism (30) there is an associated at least one primary cutter (11) of the primary breakage mechanism (10). Accordingly, in some embodiments it is possible that there may be more than one primary cutters (11) associated with a single secondary cutter (31), such that the primary breakage mechanism (10) on actuation applies the breakage force to break rock fragments from the mine wall via the primary cutters (11), the rock fragments broken caught by the surface (20), and subsequently the secondary breakage mechanism (30) is actuated to apply the force to reduce the size of at least some of the rock fragments caught by the surface (20) via the secondary cutter (31).
[0092] In certain embodiments, and referring now to Figures 2, 3 and 7 to 9 in particular, the primary breakage mechanism (10) is actuated by a primary actuator (40) and the secondary breakage mechanism (30) is actuated by a secondary actuator (50).
[0093] In embodiments, the primary (40) and secondary (50) actuators may be independently operable. That is to say, that the primary actuator (40) may actuate the primary breakage mechanism (10) so as to apply the breakage force to the mine wall (1000) without actuation of the secondary breakage mechanism (30). In this way, the cutting head assembly (100) may, as a first action, excavate rock fragments from the mine wall (1000) without processing and extraction of said rock fragments caught by the surface (20) via the one or more ports (21) for downstream processing. This first action may be used, for example, to test the primary breakage mechanism (10) to ensure that the primary cutters (11) and any cutting elements (12) are suitable for the mine wall (1000).
[0094] In certain embodiments, in alternative to the above, the secondary actuator (50) actuates the secondary breakage mechanism (30) subsequent to the primary actuator (40) actuating the primary breakage mechanism (10). That is to say, following actuation of the primary breakage mechanism (10) by the primary actuator (40), the secondary breakage mechanism (30) is actuated by the secondary actuator (50). In this way, first the primary breakage mechanism (10) is actuated to apply the breakage force to the mine wall (1000) and break rock fragments therefrom, and the secondary breakage mechanism (30) is actuated to apply the force for reducing the size of at least some of the rock fragments of the mine wall (1000) caught by the surface (20).
In other words, in some embodiments, actuation of the primary (40) and secondary (50) actuators may be synchronised so that the primary (10) and secondary (30) breakage mechanisms interoperate to move rock fragments off of the surface (20) through the one or more ports (21) for downstream processing. As described above, this may involve reducing the size of rock fragments caught by the surface (20) to allow at least the reduced size to pass through a port (21).
[0095] In any one of the above embodiments comprising the primary (40) and secondary (50) actuators, the primary (40) and/or secondary (50) actuators may be hydraulic actuators of a type well known in the art.
[0096] In the embodiment illustrated in Figure 3, the primary actuator (40) is configured to receive at least a portion of the shank (14) of the primary breakage mechanism (10) therein. In this way, the primary actuator (40) is able to reciprocate or actuate the primary breakage mechanism (10) to transmit the breakage force to break the rock fragments from the mine wall (1000).
[0097] In certain embodiments, as illustrated by Figures 1, 2 or 9, the cutting head assembly (100) includes a fluid passageway (22) located within a housing (23) which extends between the or each port (21) and an outlet (26).
[0098] Continuing now with reference to Figure 9, there is shown a sectional view of one of the ports (21) and the fluid passageway (22). As shown, the port (21) shown here is shaped to assist with guiding at least the reduced size rock fragments through the port (21) and into the fluid passageway (22). In the present case, the shape of the port (21) is such that it narrows as it depends towards the fluid passageway (22).

[0099] In the above embodiment, and with reference now to Figure 2, the fluid passageway (22) is sealed between the or each port (21) and the outlet (26) so as to permit transportation of the reduced size rock fragments therebetween on application of a negative pressure or a suction pressure by suitable means. In this way, a suction pressure may be applied via the outlet (26) to the one or more ports (21) and the fluid passageway (22) therebetween to create a vacuum which effectively transports at least the reduced size rock fragments received within the one or more ports (21) to the outlet (26) via the fluid passageway (22) for downstream processing. It will be appreciated, that in this embodiment, at least the reduced size rock fragments are sized and shaped to be transported through the one or more ports (21) via the fluid passageway (22) to the outlet (26).
[00100] In certain embodiments, and as is illustrated by Figures 1, 15 and 16, the outlet (26) is proximal to a drive gear (24) located on the housing (23). In the present case, the drive gear (24) is a swing gear located on or near a top portion (25) of the housing (23). However, it will be appreciated that other mounting arrangements may be possible.
[00101] In the present case, and with reference now to Figure 15, the suction pump (210) of the miner body (200) shown here comprises a conduit (230) which is connected to the suction pump (210) at one end, and connected to the outlet (26) of the cutting head assembly (100) at an opposite end. In this way, the suction pump (210) of the miner body (200) can apply a suction pressure to transport at least the reduced size rock fragments from the or each port (21) to the outlet (26) and subsequently to the miner body (200) via the conduit (230).
[00102] The conduit (230) may have any suitable form. For example, the conduit may comprise a flexible conduit, such as a hose or the like, sized and shaped so as to be able to apply the suction pressure to the outlet (26) and subsequently the or each port (21), and to be able to transport the reduced size rock fragments therein for downstream processing.
It will also be appreciated that the conduit (230) must be sealed at both ends connecting at the suction pump (210) and the outlet (26), to allow for the maintenance of a suction pressure which is sufficient to transport rock fragments which for downstream processing whilst suspended in a fluid or slurry.
[00103] In certain embodiments, as is illustrated by any one of Figures 12 to 16, the drive gear (24) is configured to engage a connecting gear (220) of the miner body (200) to thereby connect the cutting head assembly (100) to a mining system (300) via the miner body (200). As described above, the drive gear may comprise a swing gear (27) capable of rotating the cutting head assembly (100) about an axis of the connecting gear (220) of the miner body (200).

[00104] In certain embodiments, the swing gear (27) allows for rotation of the cutting head assembly (100) over about 190 degrees about the axis of the connecting gear (220). In this way, advantageously the cutting head assembly (100) may be rotated about the axis of the connecting gear (220) so as to maintain engagement with the mine wall (1000) as illustrated by Figure 15. It will be appreciated that the degree to which the cutting head assembly (100) may be rotated about the axis of the connecting gear (220) is dependent on the cutter head assembly (100) size relative to the miner body (200).
[00105] In the above embodiment, the drive gear (24) transmits a feed force from the miner body (200) to the cutting head assembly (100) which is intended to drive progression of the cutting head assembly (100) and the miner body (200) through a mine shaft created in the mine wall (1000) as illustrated by Figure 15. It will be appreciated that the feed force is resultant of a mass of the miner body (200) applied to the cutting head assembly (100). It will also be appreciated that a maximum feed force that may be applied is roughly equal to the maximum weight of the miner body (200). That is to say, the feed force applied to the mine wall (1000) via the cutting head assembly (100) may depend on the weight of the miner body (200) being picked up or slacked off via an arrangement of pulleys, drawworks and the like connected and controlled by the mining system (300) in order to engage the mine wall (1000) and progress the cutting head assembly (100) through the created mine shaft. A person skilled in the art will appreciate that the term "feed force"
may be interchangeable with other terms such as "slack off force" or "drive force", so as the term references the force applied to drive/progress the cutting head assembly (100). Also in the above embodiment, the feed force drives the cutting head assembly (100) to engage the mine wall (1000) and subsequently permit the primary breakage mechanism (10) to engage the mine wall (1000) by actuation. In this embodiment, the combination of the feed force and the percussive force of the primary breakage mechanism (10) permit the cutting head assembly (100) to engage and maintain engagement with the mine wall (1000).
[00106] Although the above described embodiment involves the miner body (200) applying the feed force to the mine wall (1000) via the cutting head assembly (100), it will be appreciated that the miner body (200) may not necessarily be required to apply the feed force if the mine wall (1000) is not initially engaged with the cutting head assembly (100) at a "horizontal" position, as is illustrated by Figures 12, 13 and 17 to 19. By way of example, if the cutting head assembly (100) is engaged with or in contact with the mine wall (1000) without the application of the feed force, the primary breakage mechanism (10) is actuated to apply to the mine wall (1000) the breakage force to break rock fragments from and excavate the mine wall (1000).

[00107] Additionally, as the primary breakage mechanism (10) actuates so as to excavate the mine wall (1000) via percussive forces, these percussive forces combined with the feed force may generate p-wave energy exiting at the or each primary cutters (11) or the one or more cutting elements (12) to further induce tensile failure of the mine wall (1000).
Furthermore, the feed force from the miner body (200) to the cutting head assembly (100) may be up to a total weight of the miner body (200) at the primary breakage mechanism (10). That is to say, for example, if the miner body (200) has a weight of up to 2 tonnes, then the feed force that may be slacked off and imparted via the cutting head assembly (100) at the primary breakage mechanism (10) is up to 2 tonnes.
[00108] In certain embodiments, the housing (23) of the cutting head assembly (100) is sealed such that the cutting head assembly (100) is operable when submerged in a fluid or slurry.
By way of example only, sealed areas of the cutting head assembly (100) may include any one or more of the housing (23), the fluid passageway (22), and the primary (10) and the secondary (30) breakage mechanisms. In this way, the cutting head assembly (100) is operable in an environment where the mine wall (1000) and the subsequently resultant mine shaft is filled with the fluid or slurry. It will be appreciated by those skilled in the art, that the fluid or slurry in which the cutting head assembly (100) may operate could be, for example, water or a bentonite clay/water mix depending on the geology of the mine wall (1000) and water table conditions of the environment of the mine wall (1000).
[00109] In certain embodiments, not illustrated, the cutting head assembly communicates with a control system which actuates and monitors the primary (40) and secondary (50) actuators of the primary (10) and secondary (30) breakage mechanisms. For example, the cutting head assembly may communicate with a control system which monitor the hydraulic pressures and flows in each of the primary (40) and secondary (50) actuator.
[00110] In certain embodiments, the control system comprises a remote control interface supporting remote monitoring and control of the primary (40) and secondary (50) actuators of the primary (10) and secondary (30) breakage mechanisms. The control system may be programmable so as to automate the actuation of the primary (40) and secondary (50) actuators reactive of their monitored activity. It will be appreciated that the control system, and subsequently the remote control interface, could be located at surface level and outside of the resultant mine shaft created during excavation of the mine wall (1000) and include communication infrastructure and equipment to support communication with one or more communication interface modules on board the cutting head assembly. Suitable communication infrastructure and equipment would be known to a person skilled in the art.

[00111] In this way, advantageously, the cutting head assembly (100) may be operated and monitored at a safe distance from the mine wall (1000) without placing an operator in any hazardous situation resultant of excavating the mine wall (1000).
[00112] In certain embodiments, with particular reference to Figure 11, the cutting head assembly (100) may further comprise an adapter plate (60) configured to be removably attachable to the housing (23). In the present case, the adapter plate (60) comprises one or more lifting means (61) enabling handling and transportation of the cutting head assembly (100).
It will be appreciated, although not illustrated, that the adapter plate (60) may cover and protect the outlet (26) so as to prevent ingress of any unwanted particles of substances or debris during handling or transportation of the cutting head assembly (100).
[00113] In certain embodiments, the mining system (300) (referring to any one of Figures 12 to 14) is downstream of the cutting head assembly (100) to receive rock fragments from the cutting head assembly (100).
[00114] In the present case, and as is illustrated in the Figures, the mining system (300) is a vertical mining system which creates a vertical to sub vertical mine shaft by utilising the above described cutting head assembly (100) to excavate the mine wall (1000). A
vertical mining system (300), when used with the cutting head assembly (100), may permit access to smaller scale mineral deposits without the need for expansive excavation such as those employed in either of explosive excavation or mechanical rock fragmentation excavation. In an alternative case, not illustrated in the Figures, the mining system (300) is a mining system capable of creating a near-horizontal, sub-horizontal or angled mine shafts or tunnels by utilising the above described cutting head assembly (100) to excavate the mine wall (100). The described cutting head assembly (100), in this alternative case, may permit access to mineral deposits that largely span in a horizontal or near-horizontal orientation. As will be appreciated by the disclosure of the above two cases, the cutting head assembly (100) may be utilised to create an angled mine shaft.
[00115] The vertical mining system (300) illustrated in any one of Figures 12 to 16 may be a closed loop mining system comprising a base carrier (310) such as a hydromill or trench cutter (illustrated), a solid separation and sorting unit (320), a mineral processing unit (not shown), tailings and waste integration unit (not shown) and a filling system (not shown). The composition of the closed loop mining system is preferentially modular such that the system is easy to commission and decommission, and is easily transported to and from a site.
[00116] It will be appreciated that although, in some embodiments, the base carrier (310) may comprise a hydromill or trench cutter, it is possible that other types of base carrier (310) may be used. For example, the base carrier (310) may be a duty cycle crane (not shown) configured for use in the vertical mining system (300). Indeed, the base carrier (310) may be any suitable type of base carrier which is selected to excavate rock fragments from the mine wall (1000) to create the resultant mine shaft in a vertical, sub-vertical or near-vertical orientation.
Suitable types of base carrier (310) would be readily available and typically used in the foundation industry. One example of a suitable base carrier (310) is a base carrier (310) having a capacity to reach depths of, for example, 250m.
[00117] The base carrier (310) comprises control lines, hoses and the drawworks cables necessary to supply the hydraulics, electrical power and the fluids utilised to operate the miner body (200) and subsequently the cutter head assembly (100). The drawworks cables may be spooled in drums located on the base carrier (310) and is used to support the weight of the miner body (200) and subsequently the cutter head assembly (100). In such embodiments, the above described feed force may be a force which results from "slacking off' or "picking up" the miner body (200) as is imparted by the drawworks cables of the base carrier (310).
[00118] The control system and the remote control interface may be located at the base carrier (310) for actuating and monitoring the primary (40) and secondary (50) actuators of the primary (10) and secondary (30) breakage mechanisms.
[00119] With reference now to Figures 15 and 16, in certain embodiments, the miner body (200) operates in conjunction with the cutting head assembly (100). In the present case, the miner body (200) includes the suction pump (210) centrally disposed between one or more pairs of steering plates (240) and one or more crawler tracks (250), the connecting gear (220) disposed on an underside of the miner body (200) concealing the conduit (230), and a hoist mechanism (260) disposed on a topside of the miner body (200).
[00120] The one or more pairs of steering plates (240) operate in combination with the one or more crawler tracks (250) and the hoist mechanism (260) to follow the excavation of the mine wall (1000).
[00121] The hoist mechanism (260) connects the miner body (200) to the base carrier (310) via the drawworks cables, the control lines and hoses of the base carrier (310). It will be appreciated that the hoist mechanism (260) coupled with the drawworks cables act so as to provide the feed force from the miner body (200) to the cutter head assembly (100).
The hoist mechanism (260), in one embodiment, comprises a level wind system to help maintain spooling of wire into a hoist drum.

[00122] The steering plates (240), in one embodiment, may comprise one or more steering actuators for moving the steering plates (240) about an axis so as to enable the steering plates (240) to contact walls of the excavated mine shaft. In certain embodiments, the actuators are able to retract the steering plates (240) away from the walls of the excavated mine shaft to assist in retrieval of the miner body (200) and thus the cutting head assembly (100) from the excavated mine shaft.
[00123] Retracting the steering plates (240) via the one or more actuators also assist in positioning the steering plates (240) to best absorb reactive forces created by the percussive force of the primary breakage mechanism (10). The steering plates (240) may also function so as to lock the miner body (200) at a position in the mine shaft, and thus position the cutter head assembly (100) allowing the feed force from the drive (24) and/or swing (27) gears to engage/excavate the mine wall (1000) by actuation of the primary rock breakage mechanism (10). It will be appreciated that with the steering plates (240) locked and engagement of the mine wall (1000) for excavation, the steering plates (240) advantageously absorb reactive forces created by the percussive force of the primary breakage mechanism (10). It will be appreciated that in sub-horizontal or near-horizontal mine shafts or tunnels, the steering plates (240) operate in sub-horizontal positions to drive the miner body (200) and thus the cutting head assembly (100) forward, via the feed force, in the required direction.
[00124] The connecting gear (220), in one embodiment, may comprise a drive motor for the connecting gear (220) so as to impart drive on the gear (220) and subsequently rotate the cutting head assembly (100) about the axis of the connecting gear (220) via the swing gear (27). In certain embodiments, with particular reference to Figure 15, the drive motor rotates the cutting head assembly (100) about the axis of the connecting gear (220) illustrated by dashed lines X-X.
Rotation of the cutting head assembly (100) about the axis as shown allows the actuation of the primary (10) and secondary (30) breakage mechanisms to mine the mine wall (1000) so as to permit drive of the cutting head assembly (100) and subsequently the miner body (200) through the resultant mine shaft. It will be appreciated that in this way, the rotation of the cutting head assembly (100) about the axis of the connecting gear (220) clears the mine shaft so as to allow progression of the cutting head assembly (100) via the feed force applied by the miner body (200).
[00125] An exemplary method by which the cutting head assembly (100) of any one of the above embodiments excavates rock fragments from the mine wall (1000), may include the steps of:
1. Slacking off the miner body (200) so as to apply the feed force at the primary breakage mechanism (10) of the cutting head assembly (100) and engage the mine wall (1000);

2. Actuating the primary breakage mechanism (10) to apply, to the mine wall (1000), the breakage force (the percussive force) for breaking rock fragments from the mine wall (1000) via tensile failure;
3. Catching the resultant rock fragments on the surface (20);
4. Actuation of the secondary breakage mechanism (30) to apply the force (the shear force) for reducing the size of at least some of the rock fragments caught by the surface (20) so as to allow at least the reduced size rock fragments to move off of the surface (20) through the one or more ports (21);
5. Application of the suction pressure via the suction pump (210) of the miner body (200) to transport the reduced size rock fragments from the one or more ports (21) through the fluid passageway (22) and subsequently the outlet (26) for downstream processing;
6. Subsequent to above steps 1 to 5, as the mine wall (1000) is sufficiently excavated and is creating the mine shaft, the miner body (200) is slacked off further to force the cutting head assembly (100) and the miner body (200) into the created mine shaft to continue excavation of the mine wall (1000).
[00126] It will be appreciated in any one of the above embodiments, and as illustrated in any one of the Figures, that the cutting head assembly (100) is also particularly designed such that it can be detached from the miner body (200) in a modular manner. That is to say, one or more cutting head assemblies (100) with various primary cutters (11), cutting elements (12) and/or secondary cutters (31) may easily be attached and detached from the miner body (200) during excavation of the mine wall (1000). This is particularly advantageous if the cutting head assembly (100) or any one of the primary cutters (11), cutting elements (12) and/or secondary cutters (31), require replacement or exchange in response to the mine wall (1000) geology or due to damage.
[00127] It will be appreciated in a number of the embodiments described above, that the cutting head assembly (100) may exploit a number of factors in order to achieve effective rock breakage in the mine wall (1000). In particular, the combination of the primary (10) and secondary (30) breakage mechanisms applying both percussive and shear forces to target both tensile and shear stresses in the rock.
[00128] Additionally, the arrangement of the primary cutters (11) and/or the cutting elements (12) of the primary breakage mechanism (10) may advantageously allow the cutting head assembly (100) to combine the feed force supplied by the miner body (200) and the percussive force applied by the primary breakage mechanism (10) to exploit weaknesses of hard rock and ore bodies whilst minimising wastage whilst mining the wall (1000) due to the predictable size of the resultant reduced size rock fragments for improved downstream rock fragment processing.
[00129] A further advantage of the cutting head assembly (100) is that it suits use in a vertical mining system (300). In this way the mine wall (1000) and the resultant mine shaft is excavated vertically to sub vertically (i.e. sub horizontally), depending on geological conditions of the mine wall (1000), thus advantageously being economical when targeting smaller scale mineral deposits and minimising environmental footprint.
[00130] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.
[00131] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.
[00132] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the disclosure as set forth and defined by the following claims.

Claims (26)

24

1. A cutting head assembly for excavating rock fragments from a mine wall, the cutting head assembly comprising:
a primary breakage mechanism actuable to apply, to the mine wall, a breakage force for breaking rock fragments from the mine wall;
a surface for catching the rock fragments broken from the mine wall, the surface having one or more ports associated therewith; and a secondary breakage mechanism operatively associated with the surface, the secondary breakage mechanism actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface so as to allow at least the reduced size rock fragments to pass through a respective port for transportation to downstream processing.

2. The cutting head assembly of claim 1, wherein the primary breakage mechanism comprises one or more primary cutters for breaking rock fragments from the mine wall.

3. The cutting head assembly of claim 2, wherein the or each primary cutters comprise one or more cutting elements for excavating rock fragments from the mine wall.

4. The cutting head assembly of any one of the preceding claims, wherein the breakage force is a percussive force applied by actuation of the primary breakage mechanism.

5. The cutting head assembly of claim 4, wherein the percussive force of the primary breakage mechanism provides between 50 to 1000J of impact energy at 20 to 400Hz to break rock fragments from the mine wall.

6. The cutting head assembly of claim 5, wherein the percussive force of the primary breakage mechanism provides between 300 and 400J of impact energy at a frequency of between 60 and 70Hz to break rock fragments from the mine wall.

7. The cutting head assembly of any one of the preceding claims, wherein the secondary breakage mechanism comprises one or more secondary cutters.

8. The cutting head assembly of claim 6, wherein the or each secondary cutter comprises one or more blades reducing the size of at least some of the rock fragments caught by the surface.

9. The cutting head assembly of claim 8, wherein the or each blade is proximally associated with the or each port.

10. The cutting head assembly of any one of claims 8 or 9, wherein actuation of the secondary breakage mechanism moves the or each blade so as to shear at least some of the rock fragments caught by the surface and allow the reduced size rock fragments to move off of the surface through the proximally associated port.

11. The cutting head assembly of any one of claims 7 to 10, wherein the or each secondary cutter of the secondary breakage mechanism is associated with at least one of the primary cutters of the primary breakage mechanism.

12. The cutting head assembly of any one of the preceding claims, wherein the primary breakage mechanism is actuated by a primary actuator and the secondary breakage mechanism is actuated by a secondary actuator.

13. The cutting head assembly of claim 12, wherein the primary and secondary actuators are independently operable.

14. The cutting head assembly of any one of claims 12 or 13, wherein the secondary actuator actuates the secondary breakage mechanism subsequent to the primary actuator actuating the primary breakage mechanism.

15. The cutting head assembly of any one of the preceding claims, wherein the assembly further comprises a fluid passageway concealed within a housing and a drive gear mounted on a top of the housing, the fluid passageway extending between the or each port and an outlet.

16. The cutting head assembly of claim 15, wherein the fluid passageway is sealed between the or each port and the outlet so as to permit transportation of the reduced size rock fragments therebetween on application of a negative pressure or a suction pressure.

17. The cutting head assembly of any one of claims 15 or 16, wherein the outlet is proximal to the drive gear on the top of the housing and configured to connect to a suction pump of a miner body.

18. The cutting head assembly of anyone of claims 15 to 17, wherein the drive gear is configured to engage a connecting gear of the miner body to thereby connect the cutting head assembly to a mining system via the miner body.

19. The cutting head assembly of claim 18, wherein the drive gear comprises a swing gear capable of rotating the cutting head assembly about an axis of the connecting gear of the miner body.

20. The cutting head assembly of any one of claims 17 to 19, wherein the drive gear transmits a feed force from the miner body to the cutting head assembly.

21. The cutting head assembly of claim 20, wherein the feed force is proportional to an applied weight of the miner body.

22. The cutting head assembly of any one of claims 20 or 21, wherein combination of the feed force and the percussive force of the primary breakage mechanism permit the cutting head assembly to engage and maintain engagement with the mine wall.

23. A cutting head assembly for excavating rock fragments from a mine wall, the cutting head assembly comprising:
a primary breakage mechanism actuable to apply, to the mine wall, a breakage force for breaking rock fragments from the mine wall;
a housing comprising a fluid passageway and a surface for catching the rock fragments broken from the mine wall, the surface having one or more ports associated therewith, wherein the fluid passageway extends between the one or more ports and an outlet;
a secondary breakage mechanism operatively associated with the surface and proximal to the one or more ports, the secondary breakage mechanism actuable to apply a force for reducing the size of at least some of the rock fragments caught by the surface so as to allow at least the reduced size rock fragments to pass through a respective port; and wherein, in use, the secondary breakage mechanism actuates subsequent to the primary breakage mechanism and a suction pressure applied to the outlet transports the reduced sized rock fragments via the one or more ports to the outlet for downstream processing.

24. A method for excavating rock fragments from a mine wall, the method comprising:
providing a cutting head assembly according to any one of claims 1 to 23; and operating the cutting head assembly to excavate the rock fragments from the mine wall.

25. A product comprising one or more rock fragments which have been excavated from a mine wall using a cutting head assembly according to any one of claims 1 to 23.

26. A system for mining excavating rock fragments from a mine wall, the system including:
a cutting head assembly according to any one of claims 1 to 23;

means controlling operation of the cutting head assembly to excavate rock fragments from the mine wall to provide a supply of rock fragments for processing; and processing means for processing the supply of rock fragments.