Modern Mining July 2015

OFF-HIGHWAY TRUCKS AND EXCAVATORS

small to mid-size open-pit mining

bad underfoot conditions, flat and steep grades, and wet and dry weather, all with equal ease. “Admittedly, rigids are probably cheaper to run over longer distances but balancing this is the fact that – being two-wheel drive – they require well-maintained, paved haul roads to operate. One often hears that rigids also offer a longer life and more reliability – but if they do, it is because they are not normally subjected to the same arduous conditions as ADTs. In terms of initial cost, ADTs are generally cheaper than similar-sized rigids.” Gillham adds that a further advantage of ADTs is that they can easily be adapted to a variety of roles. “You can turn them into water bowsers, fuel tankers, service trucks and explosive trucks, to take the most common examples. They can also easily be transferred over to civils applications when mining is in a downturn. Obviously, this is not a huge factor for mine owners but it is for mining contractors, who in many cases are active in both mining and construction.” It would be wrong, of course, to believe that ADTs have no place on larger mines. While they cannot handle the huge volumes and high impacts involved in very large scale mate- rial moving, they often have a role to play in supplementing the big rigid trucks. It is not uncommon, for example, to see rigids being dedicated to waste haulage with ADTs catering for the (generally) much smaller volumes of ore. ADTs are also well suited to the satellite-type operations that often present at large open-pit mines, which are too small to justify the cre- ation of well-engineered haul road networks and which are best served by small trucks with all-terrain capability. Gillhammakes the point that current models from virtually all the big ADT players tend to be much more fuel efficient than was the case just a few years ago. “I think the big OEMs have all put a great deal of effort into reducing fuel consumption,” he says. “In the case of Bell, we use Mercedes-Benz engines and these are renowned for their efficiency – and, for that matter, their ‘green’ credentials, as they meet all emission standards.” Bell, like most other manufacturers, has one global standard for its ADTs. “We don’t change the specification for specific parts of the world, with a high-tech machine for certain markets and a low-tech version for others,”

ADTs can easily be adapted to a variety of roles. This 35 000 litre water tanker is working at an emerald mine in Zambia (photo: Arthur Tassell).

says Gillham. “The machine we sell in Africa is the same as the machine we sell in every other market in the world. This partly reflects the fact that mining is a global industry and that big international mining groups expect the same standards to be met wherever they work and will not accept machines that compromise on safety and environmental standards on their sites.” He adds that one of the features of Bell’s

A prototype Bell B50E. This machine will succeed the ground-breaking B50D.

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July 2015  MODERN MINING  47