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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 hightemperature treatment.

CF is regarded as the best bonding phase with superior strength and reducibility in sintering. The comparison of hematite and CF reduction process was made in this study. Isothermal reduction experiments of powdered hematite and CF in a continuous stream of 30% CO and 70% N 2 at 1 123 K, 1 173 K and 1 223 K were conducted through thermo-gravimetric analysis (TGA). Reduction rate analysis revealed that the reduction of hematite comprises three independent steps (H→M→W→I), whereas that of CF mainly comprises two steps (H→M→I). The reduction of powdered hematite and CF can be described by shrinking layer model, not shrinking core model completely. Results of the ln-ln and Sharp analysis methods indicated that the reduction of hematite included two kinetics stages, namely, plane-like mechanism and then spherulitic-type mechanism. The reduction of CF only included the plane-like mechanism stage. The model free method revealed that the activation energy of hematite and CF reduction were 5.81 kJ·mol − 1 and 46.89 kJ·mol − 1 , respectively.