The transport and delivery of materials required in mining operations is often an overlooked subject, but if these activities are inefficient it can easily delay mining and mine development. Maurice Jones reports.
In devising or selecting an appropriate means of materials handling one first needs to know what materials are required. As most materials tend to be associated with the support of roof and walls, requirements can then be closely related to ground conditions.
If ground conditions are variable it follows that materials transport needs to be flexible to meet changing requirements. Support materials needed may include steel (eg, rockbolts, arches and beams, welded mesh, cable bolts, corrugated sheets, hydraulic powered supports for longwall faces), concrete (for spraying and grout in different mixes) and timber (props, beams, lagging). Other common requirements may include drill steels and bits, explosives, oils and water. Occasionally there may be emergency requirements such as to deal with fires or inundations, for rescue operations, or additional support needs. Installations and withdrawals from mining districts may require higher load capacity to handle heavy machinery or modular parts.
All these place considerable demands on any transport and handling system. These can be aggravated by ground conditions and the necessary regulations to protect worker safety by limiting manual handling.
Drive sections can be very variable in high-stress strata, and floors can be so distorted by heave or other ground movement that the means of transport has to be supported from the roof as monorails of various types rather than using floor rail-bound or trackless systems.
The dangers to personnel of trying to lift and turn with excessive loads are now widely recognised. So, in designing the transport system it has to be decided whether the materials can be carried in individual packages below the limiting mass for manual handling, or whether larger packs are needed, necessitating hoist and other ‘handling’ aids at transfer points. In all cases the dimensions of the working area have to be taken into consideration.
The Famur group of Poland makes a wide range of transport equipment, mainly designed for coal mines. This includes Pioma suspended monorails, diesel-power floor-mounted trapped rail systems, standard rail diesel locos, cable-driven suspended monorails and floor railways. In addition to the main systems, accessory equipment includes carrying units and bearing beams, travelling hoists (for transfers), braking cars, and passenger units.
Brookville Equipment of the US specialises in generally larger locomotives and rail equipment and has a separate mining division. It recently supplied two diesel locos (a 15-t and a 20-t) to Stillwater Mining in south-central Montana for the Nye operation, the same as two locos delivered previously. The new locos have the latest ‘Tier 3’ low-emission diesel engine. The locos also feature hand-held remote control for operation in tandem pairs on tight track routes. Other features include rear-view cameras, air conditioning and sound-deadening cabs. The mine employs Robbins TBMs for main tunnel driving, requiring major materials handling solutions (see photos).
With production or waste removal the major priorities it is often decided to separate the relatively unpredictable supplies handling from mineral and waste transport routes. In stratified mining it is usual to carry supplies through return airways, leaving mineral and waste a clear run through the fresh air intake drives. Even in the mining of steep ore-bodies it may be possible, for most requirements, to keep materials transport separate from rock haulage on separate levels.
Video 1: The J H Fletcher 3800 Series diesel tractor for mine hauling. It features an articulated frame and 5th-wheel or pientle-hook type hitch, four-wheel drive and pressurised enclosed cab
Video 2: Normet's concrete remixer carriers for concrete spraying in mine support