Very high speeds have meant a large increase in the volumes conveyed. Compared with the load in total there is a reduction in the weight of conveyed material per linear metre of belt conveyor and therefore there is a reduction in the costs of the structure in the troughing conveyor idler frames and in the belt itself.
The physical characteristics of the conveyed material is the determining factor in calculating the belt speed. Light material, that of cereal, or mineral dust or fines, allow high speeds to be employed. Screened or sifted material may allow conveyor belt speeds of over 8 m/s.
With the increase of material lump size, or its abrasiveness, or that of its specific weight, it is necessary to reduce the conveyor belt speed. It may be necessary to reduce conveyor speeds to a range in the order of 1.5/3.5 m/s to handle unbroken and unscreened rock of large lump size.
|Lump Size(mm)||Belt Width(mm)||Max Speed(m/s)|
Considering the factors that limit the maximum conveyor speed we may conclude:
When one considers the inclination of the belt leaving the load point: the greater the inclination, the increase in the amount of turbulence as the material rotates on the belt. This phenomena is a limiting factor in calculating the maximum belt speed in that its effect is to prematurely wear out the belt surface.
The repeated action of abrasion on the belt material, given by numerous loading onto a particular section of the belt under the load hopper, is directly proportional to the belt speed and inversely proportional to its length.