Since the product’s above-ground introduction ten years ago, this is only the eighth curved conveyor to be installed worldwide.
Replacing a head station, tail station and transfer chute installed to cope with a deflection brought on by geological faults, the curved conveyor slots in between two conventional conveyors, taking the 1,2-m-wide belt around a 12˚ corner over a 650 m radius. Also unique is the fact that a polyvinyl chloride belt, as opposed to a conventional steel-cord belt, will be used.
While the best radius achievable with a conventional conveyor belt is 2 000 m, curved conveyors can achieve radii as tight as 250 m, using a 600 mm belt.
Apart from saving the mine an estimated R1,5-million, the R630 000, 130 m installation at Middelbult brings several advantages to operational efficiencies, explains Middelbult shaft manager Hannes van Heerden.
The essential advantages of belt conveyors with horizontal curves include a reduction in investment costs as a result of the adaptation of the belt alignment to the terrain without large civil engineering works; the circumvolving of barriers such as faults; the abolition of discharge and driving stations along the conveyor track; a reduction in operating costs, especially through a decrease in downtime, and a decrease in environmental pollution by the abolition of discharge and driving stations along the conveyor track.
Deadweight forces of belt and material are used to counteract the force component in the direction of the inside curve around a corner, which means that the swinging suspended idler stations are self-adjusting and allows the 1 800 t/h capacity belt to be self-aligning.
This eliminates the need for exact positioning and time-consuming installation of the idler station before start-up, as is the case with conventional conveyor belts.
“I am of the opinion that the integration of curved conveyor systems into our operations will make them more user-friendly and less maintenance-intensive,” says Van Heerden.
Middelbult is already investigating a second installation using a 1,5 m belt and is also contemplating capitalising from the belt’s self-aligning properties by installing it in areas where conventional straight conveyor belts are having tracking problems.
The mine uses about 32 km of conveyor belt in its underground operations.
“There is a large capacity for curved conveyor belts in South Africa, not only in mining but also in industrial applications,” Betterect MD Martin Zechner believes.
“We hold the distribution licence for this Austrian patent in Southern Africa and are also looking at exports to Australia.”