Effect of Pre-wetting Treatment on the Granulation Behavior of Iron Ore Fines

Together with the conventional granulation, a proposed pre-wetting granulation for two commercial sinter mixtures consisted of six different iron ores and other auxiliary materials has been investigated under controlled laboratory conditions. A method to describe the size variation of the granules between different granulation trials was proposed and studied in the granulation of this study. It is a method by drawing a cumulative undersized curve (CUS curve) and a differential cumulative undersized curve (Delta-CUS curve) into one figure. The results indicated that (1) with more water available for granulation, more particles in a sinter raw mixture would behave as the layering fines in granules and the upper size for these layering fines would increase from 1 mm to 4.5 mm in conventional granulation; (2) compared to the results from conventional granulation, the granulation with pre-wetting treatment on iron ore fines resulted in a tighter particle size distribution and a higher permeability before ignition. At similar moisture content, more particles can be shifted into the layering fines in pre-wetting granulation than in conventional granulation; (3) Due to the preferential granule growth and the deformation of the granules, a further increase in pre-wetting degree (PWD) from 65% to 80% had little influence on the optimal permeability before ignition. Furthermore, a sinter mixture with more materials that are high in moisture absorption capacity would lead to higher optimum moisture content in granulation.