Application of X-ray microtomography to investigate the effect of raw material properties on the kinetics of iron ores granulation

In modern ironmaking, granulation is the first step of the sintering process. It is typically carried out in continuous drum granulators using water as a binder, and involves multiple components besides iron ores, such as return fines and other recycled materials (dusts, mill scale, sludges), solid fuel (coke breeze or anthracite) and fluxes (limestone, lime, olivine, dunite or dolomite) (Ball, 1973). As it is necessary to maintain a consistent quality of the granules (size distribution, porosity, strength, etc.) despite of the varying iron ore origins, the question arises as to how the properties of the iron ore particles (size and shape) influence the granulation process. The granulation process is partly influenced by the characteristic of the feed and partly by the action of cohesive force inside the drum granulator (Newitt et al. 1958). The objective of this paper is to study the effect of raw material properties on the kinetics of iron ore granulation considering in particular the mechanisms ruling wet granulation for two iron ores and to know the factors which determine the texture, shape, porosity and mechanical strength of the granules.