Simulation of potash cake strength by discrete element method

After potash ore has been mined and processed it is stored and shipped as bulk granular particles. If these particle beds are exposed to a relative humidity that is above 50%, moisture will accumulate in the bed. This causes the formation of concentrated brines on the surfaces of the particles that migrate toward the contact points between particles. If drying occurs crystal bridges at or near the contact points will form between particles. When large numbers of crystal bridges are formed per unit volume of bed, the bed is said to be caked. In this paper, the Discrete Element Method (DEM) is used to analyze the micro-mechanical behaviour of ideal spherical or ellipsoidal particles inside a potash bed and these results can be used to determine the cake strength. Hertz contact compressive stress theory is applied at each contact point between particles to resolve the stiffness matrix in the DEM analysis. The results of the DEM analysis compare well to those obtained using continuum mechanics for the case of a caked test ring in a centrifuge, especially when Poisson’s ratio has a low value.