Advancing contact angle of iron ores as a function of their hematite and goethite content: Implications for pelletising and sintering

The advancing water contact angles of 17 different iron ores have been measured. The primary constituents of the ores were hematite and goethite and compositions varied from 98% hematite through to 87% goethite. The measured ore contact angles ranged from 0° to 74°. An approximately linear correlation was found between the contact angle and the ore composition given by, θ=45x+8 (±10°), where θ is the contact angle (°) and x is the volume fraction of hematite in the ore. Hence, the hydrophobic character of the ore was observed to increase with increasing hematite and decreasing goethite content. These results are important for mineral processing operations such as pelletising and flotation. In both cases, water contact angles play a critical role. For pelletising of porous iron ore fines, the contact angle influences the amount of liquid absorbed into the pores and also the amount of interparticle liquid required to promote granulation.