4. Horizontal transportation
4.3 Material handling
derailments and good worker discipline to maintain safety standards and for these reasons the hopper transportation system has not been put into practice.
Several mines are currently testing Anglogold's prototype of the "21 'st century locomotive" where the train· can be driven from either the locomotive directly or the caboose by remote control. Thus, the train can always be driven from the front end. This saves time in terms of shunting the locomotive. Another feature of the 21 'st century locomotive is that the driver cabin and caboose are enclosed. Thus, there is a potential to utilise air conditioning for the train. This allows the train to potentially operate in return airways or in haulages with higher temperatures and by so doing, reduces the mines' cooling costs.
4.3.1.2 Standard loads and packaging
Handling of materials is greatly simplified if loads, or the majority of loads are standardised in terms of both size and packaging. Although mine material is diverse in both mass and size, the majority of loads handled can be standardised.
Ideally packaging should suit final user requirements. For this reason all material handling and packaging systems should be designed from the stope panel backwards towards the surface supply point.
4.3.1.3 Handling of material
The handling of the materials should be efficient with the transferring of material kept to a minimum, as the transfer of the material requires additional energy and usually the use of labour. In general, the amount of handling is a function of the design of the material handling system, each part of which must be subject to value analysis. Where the transfer of material is necessary, it should be accomplished through horizontal movement on ·Iow friction systems or through overhead lifting devices.
The reduction in manual labour has a number of benefits with regard to cost and cycle time, as well as avoiding potential. accidents. Where re-handling is necessary, this should be accomplished using appropriate equipment that requires minimum human effort and contact. The materials must be capable of being handled safely and in a form that will not be damaged during transportation.
Storage facilities require space and unnecessary stored materials can be considered wastage of capital earnings. Conversely, the lack of storage space can lead to congestion and a shortage of materials, which can cause production losses.
4.3.1.4 O~ganisation
The movement of the materials through the system must be completed in a manner that allows the supplies to reach their destination efficiently with the correct goods being delivered to the proper place on time. Scheduling is important, as material will normally be transported in the same haulage as rock and people. There are a number of computer based systems which can assist with the control and management of the system, however the capital cost of these
systems is significant and the decision to use them should be based on a sound business case.
4.3.2 Shaft Station
Bank and shaft station designs should be closely matched and standardised. This greatly simplifies operation and enhances safety. The following measures should be considered for the effective and efficient handling of material cars on the shaft stations.
Double track should be provided immediately adjacent to the shaft in an amount that is not less than the product of the average length of a material car and the maximum number of cars, which are expected to be handled on one shift. For example, if cars are 3 m long, and 60 cars are handled on a shift, then 180 m of double track is necessary.
Double track length
=
Car,ebgth x Carnumber=
3 m x 60 cars= 180 m
Equation 4-4: Length of double track on station
Some means of moving cars to and from the shaft must be provided. Capstan winches, purpose designed pushers and modified locomotives may be used for this purpose. The choice, design, configuration and operation of shaft safety stopping mechanisms must consider material transportation needs. This is especially the case with long material.
The provision of storage space must be done in such a manner that it does not impact on personnel or rock transportation operations. Material cars should not be stored in the tip cross cut, as this will hamper rock tramming activity.
4.3.3 Horizontal material transportation
Horizontal material transportation commences at the shaft and ends at the cross cuts or other working places such as development ends or service excavations.
To ensure the maximum utilisation of the transport car and minimum congestion in the haulages and cross cuts, material cars should be off-loaded quickly with the cars being sent back to surface as soon as possible.
The design of any material transport system should start with the requirements in the stope panel and worked back to surface. Materials should be packaged on surface in a form suitable for handling. Support elements and other materials such as cement bags should be packaged to fit on the cars and in accordance with the requirements of the stoping panel. Items not suitable for direct packaging can be loaded onto pallets or containers that are also sized for the cars. Long items including pipes, rails and switches should be transported in specially designed cars or bogies.
Horizontal organisation should be arranged such that full and empty cars are effectively handled on one shift. This "material shift" should not coincide with main rock tramming activities. This will be possible to achieve provided sufficient storage space and appropriate unloading equipment is available at the end points (Le. the cross cut).
4.3.4 Cross cut
The design of cross cuts is critical to the operation of the material transport system. Most cross cuts are required to handle rock loading, material and explosives as well as provide access to the stoping horizon. In addition, mining services such as electricity, water, compressed air and backfill converge at this point.
The provision of a properly designed material storage bay in the cross cut cannot be over emphasised. Good practice dictates that at least two days material storage capacity should be provided in cross cuts. This should not hamper other operations such as rock loading. The storage space can be provided on a separate spur line or in a prepared storage area. The latter minimises material car cycle time, but increases the frequency of re-handling.
Where monowinches or other overhead material transportation systems are used, these should be positioned to minimise the amount of subsequent re-handling required from the storage area.