Feeders and transfers : Recent developments : Bulk materials handling

This paper presents an overview of feeder design and performance with specific reference to belt and apron feeders. The need for feeders and mass-flow hoppers to be designed as integral units to promote uniform feed is emphasised. The theory relevant to feeder load and drive power determination is reviewed and methods for controlling feeder loads are summarised.The interface geometry of the feed zone is examined in relation to the draw down pattern in the hopper and the optimum conditions for uniform draw down are established. The analysis examines the interrelation between the release angle, divergence angle, aspect ratio of length to width of opening, volumetric efficiency and bulk solids flow properties to achieve a specified draw-down pattern and optimum performance. It is shown that the amount of divergence in a long slotted hopper opening decreases with increase in length to width ratio. The influence of the hopper and feeder interface with respect to the shear resistance and belt or apron slip are also examined. The problem of transferring bulk solids from belt and apron feeders onto belt conveyors is discussed. Relevant aspects of feed chute design are presented and recommendations are given for the selection of the optimum chute geometry to achieve belt conveyor feeding without spillage and with minimum belt wear.