A new Technology for Steep Incline High Capacity Open Pit Conveying
A new conveyor design is set to help reduce conventional heavy-duty truck traffic and the resulting high operating costs in open pit mines. This article presents the design and the initial findings of the feasibility study on the Chevron-Megapipe conveyor for a 350 m-deep open pit mine and a mass flow of 5000 t/h.
Andrey Minkin, Peter Börsting, Norbert Becker
(ed. WoMaMarcel - 04/7/2016)
With the subsequent flat-to-trough transition (for the troughed belt) and with the rolling in (for Megapipe), the stress condition in the bulk material will change. Once the flat-to-trough transition and roll-in procedure had been completed, the angle of incline was adjusted across the global gravitation vector until a large part of the enclosed bulk material slid down.
In a second step, the simulation was repeated, but now when only half the belt length was loaded. The goal of these simulations was to analyze the residual emptying in the inclined part of a system. With a lower degree of fill, the belt loses its clamping action on the bulk material in some extent, and the material is more likely to slide. The simulation runs clarified that the ribbing of a Megapipe prevents the material from sliding back, and the value of the critical angle of incline for a complete, automatic residual emptying (running the conveyor empty) was calculated.
Fig. 11 shows the residual emptying behavior of a conventional 35°-troughed belt with and without 50-mm-high chevron cleat ribbing in the DEM-FEM model.
In the case of a smooth troughed belt with a 35°-troughing angle (Fig. 11, left), the material starts to slide back at the angle of inclination of 22°. If the same belt has a 50-mm-high chevron cleat, the critical angle of incline is 37° (Fig. 11, right). Similar behavior was observed in DEM-FEM simulations of Megapipe with and without chevron cleat ribbing (height of 50 mm). The critical angle of incline was 29° (Fig. 12, left) for a smooth Megapipe and 46° for a Chevron-Megapipe with a 50-mm-high chevron cleat (Fig. 12, right).
A summary of the results of the DEM-FEM simulations is given in Fig. 13. This shows that the belt shape (troughed belt or pipe belt) and the height of the ribbing (0 mm, 15 mm, and 50 mm) have a decisive influence on a system’s conveyance capacity and max. angle of incline.
If we compare the results of the DEM-FEM simulations for troughed belts with and without ribbing as well as for smooth pipe belts with ContiTech findings from practice , it becomes clear that the max. angle of incline calculated with DEM-FEM simulations is realistic for the above-mentioned belts.
With the goal of checking all results from DEM-FEM simulations against reality, the development team is currently setting up a test rig (Fig. 14). In particular, this includes the impact of dynamic effects caused by the belt running across the idler stations as well as the effects of different chevron ribbings, conveying materials and properties (moist / dry), granulations, etc. The time at which sliding starts from a relevant inclination for the coarse bulk material compared to fine-grained materials in commercially-available pipe belt conveyors is of particular interest here.