Cost-efficient and Application-oriented Design of Steel Cord Conveyor Belts for the Mining Industry
Conveyor belts in the mining industry are facing ever higher demands as regards conveying capacity, conveyor length, service life and energy efficiency. In addition to designs according to various general standards manufacturers further develop their products for better economy.
Dr. Andrey Minkin
(ed. WoMaMarcel - 23/4/2015)
The installation of a transverse reinforcement in long-distance conveyors (A-A > 1000 m) is also possible, but often is not worth it because of the higher manufacturing costs of a belt. Therefore, for long-distance conveyors, sensor loops with a spacing of 50 to 250 m are installed in the belt and dangerous points of the system (generally at the head end and tail end of the system) are equipped with rip detection systems. In this case, the feeding and transfer points should be designed so that insofar as possible no impact breaks can occur because a cord in the penetration point can come loose from the belt and completely jam an idler on the conveying route and can rip the entire belt. Even modern rip detection systems are useless when it comes to preventing such damage because they are often installed for cost reasons at the head end and the tail end of the system.
Fig. 7 shows possible steel cord conveyor belt designs with sensor loops, fabric and steel cord transverse reinforcement for protection of the belt. A fabric transverse reinforcement is generally used in practice for steel cord conveyor belts, although steel cord transverse reinforcements are also being used more and more, especially in the mining industry.
Within the internal research project, the impact strength, troughing properties according to ISO 703 and according to Conti procedures, ply adhesion of cover/transverse reinforcement and transverse reinforcement/bead core according to DIN EN 28094 were studied in Contitech’s test laboratories on a so called 3D-test rig for a steel cord conveyor belt that is typical in the German lignite industry, 2200 St2500 20:8 DIN-X, for two types of steel cord transverse reinforcement, for three types of fabric transverse reinforcement, and for 2 mm auxiliary rubber covers. The width of the transverse reinforcement here was approx. half the belt width, i.e. BQA ≈ B/2.
With studies on the special Contitech 3D-test rig a belt sample undergoes multi-dimensional deformations to determine whether or not a steel cord transverse
reinforcement creeps out from the top cover.
Fig. 8 shows a schematic diagram of an impact test rig, and Table 3 presents the results of the study where borderline impact energies and belt weights for various design variants of 2200 St2500 20:8 DIN-X are compared to each other.
It is evident from Table 3 that a centrally arranged steel cord transverse reinforcement can increase the impact strength of a steel cord conveyor belt by a factor of two to three. The belt weight relative to width increases only slightly here.