Intra-Particle Water Migration Dynamics during Iron Ore Granulation Process

The influence of iron ore properties, such as ore type, mineralogical texture, and particle size, on the intra-particle water migration dynamics were evaluated using immersion method. When immersed, ores were reached 68-78% of their final saturation in first 60 s and then approached final saturation slowly. It typically took up to 1 x 10(5) s to reach final saturation. Compared with the initial and final saturation water contents of 2.8-4.0 mass% in the case of Brazilian ores, Australian ores showed higher water contents of 5-6.4 mass% due to more porous structure. While the final saturation water content was partially explained by the porosity and total pore volume of ores, the kinetics of water migration should be considered to explain the saturation curve of different ores. In terms of mineralogical texture, porous texture showed higher final saturation water contents than dense texture. Finer particles showed higher final saturation water contents than coarser particles. A revised migration model was introduced to explain the effect of pore size distribution and trapped air. It was revealed that water migration proceeds more readily in the finer pores due to the larger capillary force, which is needed to overcome the trapped air. The water migration in the coarser pores is restrained due to the weak capillary force against trapped air, resulting in lower degree of saturation at equilibrium. Compared with Australian ores, Brazilian ores showed a lower degree of saturation due to their higher proportion of coarse pores.