Measurement for Contact Angle of Iron Ore Particles and Water

Contact angle, as a key index for the wettability of iron ore particles by water, is of very important for the iron ore processing like beneficiation, sintering and pelletizing. Methods developed for measuring the contact angles generally can be divided into direct and indirect methods, which were summarized in present study and their advantages and disadvantages are all compared. Capillary rise method may be the most applicative approach for porous particles. Most of the contact angles between iron ore particles with water reported in the literatures were collected and the influence of the physical and chemical properties of iron ore particles were analyzed. The result shows that iron ore particles are hydrophilic and its water contact angles are influenced by the complicate interaction of chemical compositions, especially the content of oxy-hydroxides and the surface morphology. Generally, the water contact angle of goethite is the smallest. Complicate surface morphology suggest a better wettability. Furthermore, the penetration behavior of natural iron ore particles and synthetic iron ore particles are obviously different during the contact angle measurement. Compared with sessile drop method, capillary rise methods are more suitable for the measurement of natural iron oxides. Some empirical equations to predict the contact angle were collected and compared. The wettability can be improved by increasing the surface morphology of particles, coating of iron ore particles, and high temperature treatment.