The Influence of Drum Operating Parameters on Granulation and Product Attributes

Granulation is a size enlargement process that involves the movement of feed within the granulator (e.g., drum) to produce granules of desirable attributes for the subsequent processes. To produce good quality granules, the right operating parameters need to be tested, optimised, and benchmarked for future granulation test works or potential scale-up for pilot test works. Thus, in this paper, the effects of feed residence time (FRT), pre-wetting moisture content (PWMC), mixing and granulation moisture content (GMC), drum volume loading (DVL), and rotational speed (DOS) on the granulation of iron ore sinter feed blends (SFBs) containing a high content of magnetite concentrate were studied by using a rotary drum granulator. The resultant granules were characterised by bed permeability, particle binding strength, bulk density, porosity, and size distribution. From the results, pre-wetting the SFB with 80% of the GMC for 2 min mixing of the feed generated better results. The batch-wise drum loading of 4 and 12% at a 15 rpm drum speed produced granules of optimum pre-ignition bed permeability, strength, and uniform size distribution. Although the higher drum speeds (e.g., 40 rpm) showed a higher pre-ignition bed permeability of about 54 JPU due to the production of coarse size granules, the granules were weak, hence showed a higher bed shrinkage of 2.2 mm. Additionally, granulation kinetics studies indicated 5&ndash:7 min of granulation to be the optimum residence time. It was established that the optimum granulation moisture content strongly depended on the nature of SFBs, more importantly, the mineralogy and particle size distribution. Granulation moisture content increased with increasing magnetite concentrate levels in the SFBs. These established optimum drum operating parameters could be applied for the granulation of SFBs containing higher levels of magnetite concentrate, as it is essential to operate the drum at the right operating conditions when there is a significant variation in feed mineralogy and particle size distribution.