Field of the invention

[0001] The invention relates to modular, relocatable conveyor systems. More particularly, the present invention relates to modular, relocatable conveyors for use in mining operations.

Background of the invention

[0002] The duration of mining at any single location is typically significantly shorter than the design life of a conventional, permanent conveyor installation. There is a high capital intensity associated with a traditional overland conveyor. In addition to this there is minimal opportunity to reclaim that cost once the mining sites run out of ore. This minimal flexibility and insufficient return on investment often makes it unfeasible to use permanent conveying as the method to mine small pockets of iron ore.

[0003] Mine development plans mean that mining activity will continue to move further from the ore processing facility (OPF). As mining operations move to pits located further away from the OPF, new and/or extended overland conveyors will be required. The increasing distances between mining activity and the OPF mean that future extensions and additions to the conveying system will generally be required. The new locations may include requirements for different lengths, lift, conveyor profile and discharge arrangements. However, the new and/or extended conveying systems should also be capable of matching specific parameters (eg handling rates) of the existing systems (eg the OPF) to enable retrofitting to the existing infrastructure.

[0004] An alternative conventional means of transporting ore is via dump trucks. However, the operational cost of dump trucks becomes prohibitive when haul distances are over a certain distance, for example 5km.

[0005] In this context, there is a need for improved conveyors that incorporate features that allow rapid and economical relocation to new locations. Summary of the invention

[0006] According to one aspect of the present invention, there is provided a conveyor for conveying ore material in a mining operation, wherein the conveyor includes a plurality of structure modules which are coupled together to form the conveyor, and wherein the structure modules are adapted to facilitate dismantling of the conveyor at a first location and reassembly of the conveyor at a different, second location.

[0007] According to another aspect of the present invention, there is provided a method of installing a conveyor as described above, including the steps of decoupling structure modules of the conveyor at the first location, transporting the modules from the first location to the second location, and recoupling the structure modules at the second location, wherein each of the modules is maintained as an assembled unit throughout the method.

[0008] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

[0009] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a modular, relocatable conveyor system according to one embodiment;

Figure 2 is a side elevation view of the modular, relocatable conveyor system;

Figure 3 is a perspective view of a run of conveyor module according to one embodiment;

Figures 4, 5 and 6 are plan, front and side elevation views respectively of the run of conveyor module; Figure 7, 8 and 9 are perspective, plan and side elevation views respectively of a stack of the run of conveyor modules;

Figures 10, 11 and 12 are plan, side and front elevation views respectively of a head end of the conveyor system according to one embodiment;

Figures 13 and 14 are perspective views respectively of the head end;

Figures 15, 16 and 17 are perspective, front and side elevation views respectively of a gantry module according to one embodiment;

Figures 18, 19 and 20 are perspective, front and side elevation views respectively of a gantry module for fitting to an alternative run of conveyor module;

Figures 21 and 22 are front and side elevation views respectively of a trestle according to one embodiment;

Figures 23 and 24 are plan and side elevation views respectively of a drive assembly according to one embodiment;

Figure 25 is a perspective view of a conveyor take up unit according to one embodiment;

Figures 26 and 27 are plan and side elevation views respectively of the conveyor take up unit; and

Figures 28 and 29 are sectional views of the conveyor take up unit taken at sections A-A and B-B respectively.

Detailed description

[0010] Figures 1 and 2 illustrate a modular, relocatable conveyor system 100 according to one embodiment of the present invention. The conveyor system 100 is configured to be relocatable, adaptable and expandable. Preferred embodiments of the system allow for increases in throughput through minimal mechanical changes. For example, the length of the conveyor can be modified through incremental addition or removal of conveyor modules, in addition to the relocation of the tail pulley. This allows the conveyor to be relocated with minimal sunk cost, as the predominant fabrication cost can be re-used at the new location. Modularity of components of the conveyor system 100 allow for compact storage, rapid relocation and transport, for example, the structural modules are preferably stackable as described in more detail below. In preferred embodiments, the conveyor frames are designed and constructed from materials to give resistance to higher forces from variable ground conditions, as is typical for above-ground conveying. Modular components of the conveyor system 100 such as the pulley skid, drive skid, take up winch and trolley pulleys may be economically relocated without leaving excessive sunk costs in concrete footings.

[0011] In preferred embodiments, the modular, relocatable conveyor system 100 is configured with a rated handling rate of at least about 3000 tonnes per hour (tph), preferably at least about 5000 tph. It is envisaged that the conveyor system may be upgraded to deliver about 7500 tph, for example through the addition of a drive motor / reducer module, variable voltage variable frequency (W ) drive, drive field wiring and correctly rated conveyor belt, preferably without any changes to other components.

[0012] In preferred embodiments, the conveyor drives, drive frames, loop take up, belt maintenance equipment, run of conveyor structures, loading stations, tail frame, gantries, trestles, switch room and field electrical equipment are configured such that each can be relocated to suit future mining requirements. Each of the above-listed items are preferably configured be able to be lifted, transported, stored and re-installed as complete modules, without disassembly or removal of pulleys, couplings, all guards, fire and washdown service pipework, electrical junction boxes, cable tray, field devices and wiring. Further, the foundations are preferably configured to enable rapid relocation. [0013] In one example, the modular, relocatable conveyor system 100 may configured according to the following specifications:

11 Ϊ 1 Ί ¾peciTicanon

Belt Width 1800mm

Belt Speed 3.0-4.5m/s

Number of head end drives Expandable up to maximum designated

throughput three head end drives without changing pulleys or support structure.

Pulleys Minimal number of pulleys.

High tension structures To suit the requirements of ST3200 belt,

operating at 6: 1 FOS with two primary drives, a single secondary drive and a 200kN gravity take up.

Conveyor crash / stop tension of 1560kN.

Idler roll configuration Carry: 5 roll offset, 45 degree trough angle sets.

Return: 3 roll sets

Brakes Provision for the later addition of brakes

where required

Impact zone idler frames Able to be fitted to and removed from the conveyor without cutting the belt. [0014] In preferred embodiments, the voltage rating of main conveyor drives of the conveyor system 100 matches the existing equipment spares. For example, main conveyor electric motors, variable speed drives, power transformers, electrical switchgear, idlers and conveyor belting preferably have spares commonality. In one example, the main conveyor drives run at 690V to match existing components. The existing switchroom may be used to mount electrical, control and communication equipment for the conveyor system 100. In one example, the power supply for the conveyor main drives is via a double boot 22kV circuit breaker connection on an existing 22kV ring main unit. This may require installation of a power transformer for the main conveyor drives. The conveyor tail end may be powered by any suitable means, eg a diesel generator.

[0015] Variable Speed Drives (VSD) are preferably used to power the main conveyor motors. In preferred embodiments, the default drives configuration comprises 1MW, 690V, 6 pole motors with Ml 50 frame size, however, alternative embodiments may be applicable. Safe Torque Off (STO) function is preferably provided on all VSD. The variable speed drives preferably comprise 690V, 12 pulse for the conveyor drives and 690V, 6 pulse for the apron feeder.

[0016] In some embodiments, the conveyor system 100 discharges at the head end 20 to a surge bin 22, eg a 550 tonne bin, located over the OPF feed conveyor. The surge bin provides operational decoupling of the conveyor system 100 and the OPF. The resultant surge volume accounts for stopping time differences between the conveyor system 100 and the OPF. In some embodiments, the surge bin is fitted with an apron feeder that discharges to the OPF feed conveyor. The bin design may include an overflow chute that discharges overfill material safely when this feature is enabled in the control system by adjusting level control limits. The bin arrangement may further include retaining walls to protect the OPF feed conveyor and the drive station of the conveyor system 100. Preferably, the bin discharge point onto the OPF feed conveyor allows for material from upstream loading points on the OPF feed conveyor to pass the new loading point unobstructed without causing any spillage from the OPF feed conveyor belt. For example, the clearance provided above the existing OPF feed conveyor burden depth may be about 500mm with incoming impact protection against periodic larger rocks. Further, the loading zone onto the OPF feed conveyor may include an impact zone 24. The impact zone may, for example, comprise a suitable amount of heavy dutyjack down idler frames fitted with heavy duty bullnose rubber disk or lagged type impact idlers.

[0017] In some embodiments, the tail end of the conveyor includes provision for loading from one or more run-of-mine (ROM) crusher discharge conveyors at an impact station. In one example, two 2500tph ROM discharge conveyors may be provided, which are fed by apron feeders with a possible surge rate of 125% of the rated tonnage. Preferably, the conveyor may be extended about 40m past the crusher station loading station to provide for a future load point.

[0018] In some embodiments, the main run of conveyor (ROC) structure 30 of the conveyor system 100 is configured to be placed directly on a foundation constructed to light vehicle (LV) roadway standards. The LV roadway is preferably of sufficient width and grade to allow installation of the conveyor system as well as passage of LV maintenance vehicles along one side of the conveyor, a 1.5m passageway on the non-roadway side and provision of adequate road drainage.

[0019] In one embodiment, the foundations comprise fixed anchor modules spaced at about 100m to surveyed positions, with the floating modules (nominally with steel kid or pad footings) aligned and positioned in about 10m increments therebetween without requiring surveying requirements.

[0020] The mounting arrangements may comprise concrete sleepers, steel sleepers, pontoon feet, earth anchors, or may not include anchors, but are preferably designed to provide stability and security under wind loading, including module structure security and empty belt security, whether with or without a roof.

[0021] The ROC modules 32, comprising run of conveyor structure and idler arrangement, are configured to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of guarding, idlers, electrical field wiring, terminal boxes and other ancillary equipment. To assist with relocation, the ROC modules are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity. [0022] In preferred embodiments, the ROC module may be between about 6m and 12m in length, to enable transportation in standard shipping containers. In preferred embodiments, the ROC module 32 excludes the drive assemblies (ie pulley skids and drive modules), brakes, take up arrangement and conveyor belt. Importantly, to ensure ease of relocation of the conveyor system 100, the ROC modules are configured to be robust, rapidly deployed and recovered and to leave a minimal amount of concrete behind.

[0023] In preferred embodiments, the ROC modules 32 are able to be stored in a space- effective manner. For example, as illustrated in Figures 7 to 9, the ROC modules 32 may be stackable. The stackable modules 32 are preferably configured to ensure easy, stable and secure stacking, and to ensure that the installation length of each stack enables the stacks to be conveniently transported and/or stored. For example, the specific offset idler arrangements may be cross fit to allow stacking of the modules. The modules may additionally or alternatively be nestable, foldable, and/or interconnectable.

[0024] In preferred embodiments, the ROC module 32 is configured to enable vertical and/or horizontal re-alignment where installed on unstable ground such as spoil piles, without disassembly or removal of the belt. For example, Figure 3 illustrates adjustable legs 34 on the ROC module 32. Further, the idlers are preferably tracked and adjustable to enable re- centering if required. In one example as illustrated in Figures 3 and 4, the idler configuration may comprise five roll carry idlers 36 and three roll return idlers 38. Alternatively, the idler arrangement may comprise three roll carry idlers and two roll return idlers.

[0025] Preferably, the ROC module is further configured such that the belt may be tracked without undoing fasteners. The ROC module preferably also comprises geometries and features that prevent the build-up of material on fixed items such as cross members. In one example, the minimum clearance under the return belt is about 650mm and the minimum belt edge clearance is about 250mm per side. In preferred embodiments, the carry and return idler spacing is maximised, to reduce component count and decrease installation time, while still ensuring that the selected idler spacing does not adversely impact on belt life. The ROC module further comprises regular fixed anchor points that lock the structure alignment and provide a reference point for alignment of structure during installation. [0026] Further, the ROC module may include fixing points for rain covers and/or other features, such as inverted return idlers, to shed water from the belt. Preferably, water shed points are provided at conveyor low points, or at maximum 500m spacing.

[0027] In preferred embodiments, all chutes hoppers, pulleys, drives and idlers are provided with a means of safe access eg comprising an access platform, access hatch, inspection hatch or maintenance access. Access to all maintenance points such as inspection, condition monitoring, greasing and mechanical adjustments are also preferably provided with safe access from compliant platforms where required. Remote grease points are preferably extended outside guarded areas when the actual grease point is located in an inaccessible area or behind guarding. All guarding is preferably easily removable and positively mechanically restrained such that it can only be removed using a tool.

[0028] In areas where there is risk of fly rock, such as above crushing equipment or within the potential trajectory of material within a chute, suitable guarding that can withstand the forces and prevent the rock from exiting the chute is preferably included. Any such guards are preferably removable and provided with suitably rated lifting points to ensure they can be easily removed using a crane. These guards preferably allow vision into the chute and are designed in such a way to ensure there is no risk of them becoming dislodged and falling into the crusher or onto surrounding areas.

[0029] Impact stations are preferably designed to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of guarding, idlers, skirts, electrical field wiring, terminal boxes and other ancillary equipment. To assist with relocation, the impact stations are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity. Impact stations are preferably removable from the conveyor and installed in a new location without cutting of the conveyor belt.

[0030] In one embodiment, conveyor loading stations include support frame, heavy duty, jack down / drop down impact idlers fully interchangeable with existing site standards, skirt boards, skirt rubbers and a V plough on the return belt. The skirting systems are preferably of sufficient length to ensure that ore exits the skirt area stable and settled on the belt. The skirting systems preferably include wear liners that provide a minimum 12 month life before replacement, and are interchangeable with other wear liners on the site.

[0031] A pedestrian overpass may be provided, for example approximately evenly spaced at 1.5km locations. The overpasses are preferably designed such that they can be easily relocated to other areas along the conveyor. Any required concrete footings are preferably precast and easily relocatable.

[0032] Gantries 70 and trestles 60 are preferably configured to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of guarding, idlers, electrical field wiring, terminal boxes and other ancillary equipment. To assist with relocation, the gantries and trestles are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity. Gantry to trestle connections are preferably pinned and readily accessible from alongside the gantry, without the need for access beneath a suspended load during installation. The gantries preferably include maintenance walkways on both sides of the conveyor. The gantries supplied for the light vehicle road crossing, or other elevated areas, are preferably suitable for re-use in the head end area of a future or relocated conveyor.

[0033] The conveyor take up unit 40 is of a modular construction, with each module preferably configured to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of pulleys, guarding, idlers, skirts, electrical field wiring, terminal boxes and other ancillary equipment. In one embodiment as illustrated in Figure 25, the take up unit 40 comprises a fixed end module 41, a standard module 42, a sheave end module 43, and a winch module 44. The take up unit 40 further houses a pulley carriage 45 and idler carriage 46. To assist with relocation, the modules are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity.

[0034] The take up system preferably includes functionality where-by belt tension can be safely released for maintenance, including in the event of failure of a take up winch. The conveyor system 100 preferably includes appropriate provision for conducting safe belt maintenance, for example, appropriate belt clamping where reeling is possible at the designated location.

[0035] The conveyor drive modules 50 are preferably designed to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of guarding, lubrication and cooling equipment, electrical field wiring, terminal boxes and other ancillary equipment. To assist with relocation, the drive modules are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity.

[0036] In preferred embodiments, the drive modules 50 comprise 90 degree, torque arm mounted units mounted to the conveyor pulleys using low speed rigid couplings. Drive modules are preferably able to be fitted in any orientation, and able to be rotated in either direction. Reducers may include double extended output shafts, to facilitate possible later addition of holdbacks or brakes.

[0037] Drive pulley skids 52 are preferably designed to be removable from the plant, transported, stored and reinstalled at a new location as fully assembled units without the disassembly of pulleys (eg drive pulley 54 and drive snub pulley 56), guarding, idlers, electrical field wiring, terminal boxes and other ancillary equipment. To assist with relocation, the drive pulley skids are preferably fitted with permanent and labelled lifting points, and labelled with mass and centre of gravity. Preferably, the primary and secondary drive pulley skids are interchangeable.

[0038] The design of conveyor stringers in ground module and truss configurations is preferably compatible with a uniform lightweight easily removable cover design, eg which is compliant with AS 1170.1. Conveyors are additionally preferably fitted with head pulley cleaners and V ploughs.

[0039] Conveyor pulleys for modular conveyor system 100 are preferably standardised with existing site standards. In one example, the conveyor includes three standard types of pulleys: head and high tension pulleys (single design), drive pulleys (single design), and low tension pulleys (single design).

[0040] In preferred embodiments, earthworks fill placed by the mine comprises bulk fill, and is not sized or compacted by the mine. The conveyor system 100 preferably includes features to address potential settlement in the fill areas such as minimisation of fill depths, construction of engineered fill caps over the bulk fill, structure that facilitates fast realignment, the use of low level, short span gantries, etc.

[0041] In some embodiments, the conveyor system 100 accommodates one or more road crossings. For example, the conveyor may utilize the height from the adj acent waste dumps to overpass the roads with elevated trestles 60 and gantries 70, eg with a minimum height of 13.5m and span of 35m at heavy vehicle roads and minimum height of 5m and span of 10m on light vehicle roads. The conveyor alignment between the loading point and the head end surge bin may cross a mixture of undeveloped land, roads, equipment storage areas, water drainage channels and spoil dumps. Any suitable structures may be provided to cross other areas where the conveyor system 100 must be elevated.

[0042] In some embodiments, the conveyor alignment may include the provision of a light vehicle maintenance road on one side of the conveyor, and pedestrian access on the non- road side. Adequate drainage is preferably provided for both the maintenance road and pedestrian access.

[0043] In order to maximise production and hence minimise downtime of existing site processing infrastructure, the conveyor system 100 is designed to minimise the time associated with installation and tie-ins, for example by maximising the amount of offsite modularisation where economical, in addition to designing for onsite preassembly adj acent to the work area during normal plant operation. This approach would allow final installation to be carried out utilising fewer crane lifts and area access during isolation of the OPF conveyor.

[0044] Relocation of the conveyor system 100 preferably requires a maximum shutdown duration of 4 weeks. This includes transportation and installation of all equipment to achieve an operating conveyor, excluding the construction of civil foundations. In preferred embodiments, the civil foundations are completed prior to the critical path shutdown equipment relocation. Transportation of the modules of system 100 may involve one or more suitable method, including via crane, fork lift or other means.

[0045] In preferred embodiments, the module are designed for robustness, for example, by configuring the individual module members (eg stringers, legs, stands, cross members) with inherent resistance to torsional and parallelogram distortion, resistance to ground settlement distortions and resistance to handling / stacking and storage distortions. Further, the modules are designed with consideration for corrosion and fines build up resistance, for example when designing open structural sections, section thicknesses, water / fines pooling pockets, cross members below return belt, etc.

[0046] In one example, the conveyor system is configured to process material such as iron ore with a specific gravity of 3.0, having further parameters as described in the table below, at a rate of about 5000 tph, preferably about 7500 tph. In one example, the conveyor system is operated at the above rated tonnage throughput based on approximately 8, 160 operating hours per annum (340 days per year).

Material Angle of Repose (ROM and Primary 35 Degrees

Crushed)

ROM Moisture Content (min / average / max) 5 / 9 / 1 1 % Water

Primary Crusher Moisture Content (min / average / 5 / 9 / 1 1 % Water max)

Dust Extinction Moisture 7 % Water

Surcharge Angle on Conveyor 10 Degrees

[0047] In one example, the conveyor system 100 is capable of processing material having the parameters in the tables below:

Silica Content 6 - 15 %

[0048] The ROM feed may have the following characteristics:

Top Size Up to 1000mm Mm

P80 650 - 700 Mm P50 300 - 350 Mm

[0049] The primary crushed ore i may have the following c iracteristics:

Top Size -250 Mm

[0050] Field instrumentation of the conveyor system 100 preferably includes all necessary instrumentation, control and safety devices for the safe and efficient operation of the equipment including stop/start stations. The devices preferably include:

• Belt drift switches

• Belt rip switches

• Pull wire trip switches

• Take up limit switches

• Blocked chute detection

• Speed detection

• Belt rip detection

• Belt weigher

• Tramp Metal detection

• Resistance Temperature Detectors on motors

• Condition monitoring for pulley bearings Audible and visual start up warning devices

Remote Isolation System (RIS) that performs the function of an electrical isolation of overland conveyors for the purpose of mechanical work. RIS components may include remote panels for field activation of isolation, local HMI touch screen panels, communications link to SCADA systems and manual lock out systems.

Process Control System (PCS) including supply and configuration of I/O PLC hardware, SCADA, Historian, complete with CPU' s, I/O modules, communication modules, mounting racks, power supplies, field termination assemblies, local cabling, associated free standing enclosures and any miscellaneous items required for complete operation of the PCS controllers.

Integration of the conveyor code with the OPF PCS.

Integration of the new conveyor Load Management Spinning Reserve with the OPF High Voltage (HV) Network and communications to the Power Station.

Details for any other proprietary Control System, as deemed necessary, to optimise the performance of the equipment.

Fibre-optic cabling for PCS Network infrastructure and all associated communications Hardware (eg from SR413 PLC/Communi cation Panel, along the conveyor to marshalling panels). The Network may have a redundant ring installed along the conveyor from the Tail end switchroom to the Head end Marshalling Panel.

Cable ladders, junction boxes, field isolators, marshalling panels, miscellaneous supports (for cable ladders, marshalling panels, Junction boxes and any other associated equipment).

Solar Panels for powering up marshalling panels may be considered along the conveyor in non-powered areas. • Identify tie-in points within the existing switchroom PLC Panel, PCS Network Communication panel and electrical feeder DBs.

[0051] In one example, the conveyor system 100 is operated 24 hours per day, 365 days per year with a quarterly shutdown period of three days to achieve an operational availability of 99% or higher, excluding scheduled shutdowns. Maintenance required during the weekly maintenance period is preferably limited to online works such as inspections, clean up, lubrication, and belt cleaner maintenance. Maintenance during the scheduled maintenance is preferably limited to replacement of transfer liner plates, skirting wear plates and major component change out.

[0052] The conveyor system 100 is preferably designed to facilitate clean up by the use of washdown hoses and preferably includes the following features: washdown hose points at nominal 30m spacing along elevated gantries 60, and a minimum of 200mm clearance under the plant to allow spillage to be hosed from beneath the plant. Any externally mounted equipment is preferably designed and constructed to resist the ingress of dust and water and is preferably constructed of materials resistant to the deterioration effects of the sun's rays. Any such electrical equipment is preferably housed within an enclosure with a water resistance rating of no less than IP65.

[0053] The conveyor system 100 and associated OPF tie in are preferably designed to fulfil a service life of about 10 years without the requirement to replace any maj or mechanical or electrical components over that period. Design life for head, drive and tail end structural steel preferably exceeds 20 years. The remaining steelwork design life preferably exceeds 10 years. The stated design life requirement may exclude wear liners that are preferably designed to provide a suitable lifetime which is defined as a minimum of 6 months. Standardization of liner materials and fastening arrangements in preferred embodiments may contribute to long-life, highly wear-resilient products. As the alignment of the conveyor structure may be subject to settlement, particularly over the waste dump areas, some vertical realignment of the ROC structure may be required, preferably while the conveyor is operational. Further, as the area is typically be subject to spillage, dust generation, regular wash-down activities, heavy rainfall and occasional minor flooding, the conveyor system 100 is configured to effectively address these occurrences without creating any reliability or operational issues.

[0054] Preferably, the conveyor system 100 is configured for ease of operation and to ensure that operators can safely operate, inspect, clean and lubricate the system. All such work are preferably undertaken from permanent walkways without the need to shut down the system, carry tools, remove grates or make other special arrangements. All instrumentation and devices requiring adjustment are preferably able to be safely accessed and operated without having to stretch, stoop or twist or reach to adjust instrumentation or other commonly used devices. Permanent access platforms are preferably provided rather than the use of ladders or portable steps. All field controls and instrumentation are preferably grouped for operational use. All equipment is preferably provided with a means to allow for isolation. The conveyor system 100 is preferably also configured for ease of maintenance, such that maintenance personnel should be able to carry out their routine tasks without the need to shut down equipment. Equipment service points are preferably readily accessible.

[0055] Further, in preferred embodiments, adequate space is provided around all equipment to allow for maintenance and breakdown removal. All wearing parts are preferably readily accessible from permanent maintenance platforms. If wearing parts are required to be routinely replaced, these are preferably replaceable with only minor disassembly. All items that require either routine or breakdown maintenance, and that are heavier than 15kg, are preferably fitted with rated and labelled lifting points. Rated and labelled lifting points for supporting the required lifting equipment shall preferably also be provided for each removable item over 15kg.

[0056] Module stacking may be done differently by stacking the structure modules on each other in a nested arrangement achieving a compact height, for example by separating the legs from the stringer. Parts of the modules (for example, the stubs shown in Figure 7) may interlock so as to hold together to avoid the having the modules slide off each other inadvertently. The stringer geometry may also be selected to facilitate stacking of the dressed stringers. One way this may be achieved is by configuring the top edge of one stringer to match the bottom edge of the same stringer so that like stringers can be stacked efficiently for relocating the stack so as to transport the modules in a space-efficient arrangement. The dressed modules can be stacked if the legs are removed, for example by unbolting the legs from the modules. Alternatively, each of the modules may be maintained as an assembled unit throughout the steps of decoupling modules, transporting modules and recoupling modules. That is, the modules may be moved whole with the legs and feet attached.

[0057] In another example, each module may be configured such that the modules are either stacked with the legs off or are transported fully assembled.

[0058] The stack-ability and interlocking parts of the arrangement shown in Figures 3, 7, 8 and 9 is significant and advantageous. When decoupling modules for stacking, this may involve the decoupling of legs, enabling the direct stacking of the stringer section of the module (one leg set in case depicted, although other modules may have more than one set of legs to be removed). This may achieve a higher stacking density compared to if the legs were not decoupled.

[0059] With the stacking of the module as shown in Figures 3, 7, 8 and 9, the metal stubs and cross brace shown on each module form a stringer interlocking mechanism. Figure 7 shows that the stubs lock against each other in a form that creates rigidity and stability for stacking stringer modules in the absence of legs. It is advantageous in the embodiment shown that one set of legs detaches and the stringers locate against each other for high density stacking.

[0060] If stacked, the carry rollers stay whereas the return rollers come off with the leg set. The overland modules are designed so as to balance service life, saline water resilience, strength and weight.

[0061] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments. [0062] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0063] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.