Agglomeration Process of Wet Granular Material: Effects of Size Distribution and Froude Number

International audienceGranulation or agglomeration process of solid particles was applied in a wide range of theindustrial fields including steel making [1], pharmaceutical industry [2] and and powdermetallurgy [3]. In the iron-making industry, agglomeration process is one of the most criticalstages in the sintering process. An agglomeration drum is a rotating, cylindrical dum whichutilizes a tumble and grow action to form spherical granules in the presence of a liquid binder.More specifically, material and liquid binder are fed into the drum. As the drum rotates,material fines get tacky in the presence of the binder, and pick up more fines as they contactwith other wet particles. There are various parameters which effect on the granule formationand development including initial particle size distribution, raw material properties, fillinglevel of particles in the drum, the amount and viscosity of the binding liquid, ratio betweendrum diameter and particle size, the particle size, and rotational speed of drum.In this work, we simulate the agglomeration process of solid grains composed of sphericalparticles in the presence of a viscous liquid by means of molecular dynamics (MD)simulations [4]. We are mostly interested in application to iron ore granulation in a rotarydrum agglomerator. We are also interested in understanding the agglomeration process at theparticle scale like accretion, erosion, redistribution of binding liquid. And investigation theeffects of control parameters such as flow regime (rotational speed) which defined by Froudenumber, and initial size distribution. The presence of liquid binder is modeled as a capillaryattraction force as well as liquid viscous force. The capillary cohesion force is simulated as anattraction force at the contact between particles and expressed as an explicit function of thegap, liquid volume, surface tension and the particle-liquid-gas contact angle [5]. During therotation, the dry particles flow around the spherical granule. This state continuously occursthe accretion and erosion phenomenon between dry and wet particle. We find that the granulegrowth increases exponentially with the number of rotations of drum. This growth rate isproportional to the increase of size ratio. However, the changing of different values of Froudenumber between rolling and cascading regime can not dominate the granule growth