Simulation and analysis of blending in a conveyor transfer system

Abstract Blending granular materials is necessary to achieve consistent quality for shipping and transport. In mining stockyards, the level of blending is influenced by the operations including stacking, reclaim, conveying and transfer. While sufficient blending is often only evaluated by the quality of the as-shipped product, this paper presents a method to quantify the physical blending process at a particle level through simulation. A Discrete Element Method (DEM) modelling analysis was undertaken on a continuous belt conveyor system connected in series via perpendicular transfer chutes. Two granular materials, M1 and M2, with different densities, were modelled as spheres, each comprising a different portion of the total system throughput. Flow was modelled with M1 loading the system from one conveyor and M2 from another. The two materials were then transported and blended through a number of additional transfers up to a total of seven. Three transfer geometries having different head heights and incorporating two different deflectors were investigated. A steady state section of burden on the conveyor belt following each transfer was analysed using three different measures. The study investigated the influence of the modelled particle properties, the design of the transfer through variation in the type of deflector used and head height on blending and homogenisation. Particle properties and deflector design were both found to influence blending and homogeneity. The analysis strongly indicates that a homogenous product is attained following the seven transfers considered. The study also illustrates the use of DEM in evaluating blending in conveyor transfer systems and the approach outlined may be used to quantify the impact on overall blending operations.