Shear Cell Test and Hopper Design

Abstract

Relevance of the work. The Hopper and Bin design is the most commonly used technique of storing materials as it is a gravity fed system and is generally used for storing materials such as agricultural grains as well as mined minerals such as sand and coal. Mass flow, which is ideally the most desired flow type sees the bulk material travel uniformly with all particles in motion until all the material leaves the bin. The other types of flow generally occur with flat-bottomed bins with shallow hoppers are not seen as ideal as with this design problems such as arching and rat holing occur. The issue with the current design is that some of the material becomes stagnant in the bin, this can be costly as if the bulk material becomes stuck, degradation can occur over time. It can be observed for the Funnel and Expanded flow, the rat holing and arching occurring due to the stagnant material. Research Objective is to design a novel mass flow acrylic bin and hopper to store bulk quantities of sand without stagnation or degradation Methodology. Two separate experimental procedures were carried out including the measurement of the specific gravity of the sand, shear test and final hopper design. The data was then manipulated and plotted stress transformations and identified multiple key flow property constituents. Using values such as the yield loci and associative yield stresses the hopper half angle α and opening diameter B were tabulated. Results and Conclusions. The optimum opening diameter B for an uncompacted system is 2 mm and the hopper half angle α adjusted to 34.58o , this was tested and provided a successful mass flow hopper system. Overall, the techniques used with specific gravity and shear cell testing gave a sufficient insight into the appropriate procedure for designing efficient and accurate bin and hoppers. Then substituting the values gathered into the appropriate formulae provided a successful mass flow system for the intended bulk material which is sand.