Contribution Oral Presentation
Calibration of discrete element method parameters for modelling DRI pellets flow
DRI pellets vulnerability to successive collisions and the fine generation is a major concern of iron making industries. During the DR process, transportation, and buffer storage, DRI pellets are subjected to successive pellet-pellet and pellet-wall collisions. Depending on the impact conditions (i.e., angle, velocity, and force) and the characteristics of the pellets, various kinds of mechanical damages (attrition, fragmentation or abrasion) may occur to the pellets. Application of the numerical, analytical, and experimental methods for analysis of DRIs abrasive damage would result in the improvement of transportation and storage systems in the iron making plans. Such improvements would decrease DRIs mass loss and fine generation during DRIs handling from DR plant to electric arc furnaces. From the analytical or experimental analyses, some predictive models for DRIs damages are obtainable. Such models estimate the extent of damage as a function of material characteristics (e.g., hardness, fracture toughness, and mass-specific energy) and collisions parameters (e.g., energy, force, and velocity). The collisions parameters are obtained by simulation approaches such as the discrete element method (DEM). DEM is one of the most powerful methods for simulation of granular materials such as iron ore pellets and DRIs. This approach is capable of accurately calculating the parameters of particle-particle and particle-wall collisions. However, the accuracy of DEM results depends directly on the precision of the material parameters, which are set as the input variables of DEM simulation. To achieve reliable results in a discrete element method (DEM) simulation, it is necessary to adjust precisely the characteristics and properties of granules. The main properties for DEM simulation are size distribution, density, Young’s modulus, Poisson’s ratio, and the contact coefficients including restitution, rolling friction, and sliding friction. In the present study, these properties are determined for DEM simulation of direct reduced iron (DRI) pellets. A reliable DEM simulation would contribute to optimizing the handling system of DRI pellets in an iron-making plant. Among the mentioned properties, Young’s modulus is the most important parameter, which is usually hard to get for particulate solids. Here, a special method is utilized to precisely determine this parameter for DRI. Finally the determined parameters are experimentally validated using a set of tumbler tests.