Comparative investigation on modelling wet and sticky material behaviours with a simplified JKR cohesion model and liquid bridging cohesion model in DEM

As iron ore deposits are depleted at the face of the mine site, deeper excavation is required to meet the requirements of the supplier. During this deeper excavation, increasing clay and moisture content leads to wet and sticky material (WSM). WSM's are prone to cause problems in all phases of the materials handling stream, which is attributed to the inter-particle and boundary cohesion and adhesion forces. These characteristics can be computationally expensive to model and with the development of discrete element modelling (DEM) and advancement in computational power over the past decade, it is now more feasible to model WSM's into the DEM technique. This paper will compare two different contact models that can represent the characteristics of a WSM. The first being a simplified Johnson-Kendall-Roberts (JKR) contact model which is an expanded form of the classic Hertz contact model. This model includes the tensile forces which are in the contact zone between two bodies when they are separated, which the Hertz model failed to capture [6]. The second model is that of a liquid bridging contact, which accounts for the capillary effects and surface tension that will form between two bodies such as that of a WSM. These two models were then simulated using LIGGHTS [8] as the software platform for a DEM technique simulation. Finally, qualitative experimental verification was undertaken to assess the applicability of the proposed models, where recommendations were made as to the accuracy of each of the contact models used.