2.5.5. Other alternative processes to sintering and pelletizing

### 2.5.5.1. HPS process: hybrid pelletized sinter

carbon (100% C, d50 = 10.2 μm) excesses (10, 25 and 40%) over the stoichiometric. Samples of 0.8–2.5 g were loaded into crucibles of 75 mm length, 12 mm width and 8 mm depth, with three thermocouples placed at the bottom of the crucible. This crucible is then placed below the

Samples were analyzed by x-ray diffraction and SEM–EDX. It was observed that the main phases were Fe2O3, Fe3O4 and in some cases FeO. This indicates that a transformation took place during the experiments, carbon was mainly burnt during the process, so it was not used as reductant agent [71], and for that reason, the appearance of Fe3O4 and FeO takes place because of thermal decomposition of the iron oxide. It is possible to see in Figure 1 the

From SEM–EDX, it is clearly observed that the disperse constituent is magnetite (white), while the matrix constituent is a phase formed by silica and alumina (both coming from the crucible [72]), iron and oxygen (see Figure 2). There are, for that reason, both diffusion and melting

solar beam and displaced at a controlled speed of 0.25–0.76 mm/s.

influence of displacement speed and power in the formation of magnetite.

Figure 1. Magnetite formation as a function of power (a) and displacement speed (b).

Figure 2. Micrographs obtained with an electronic microscope (E34 P2 (a) and E25 P2 (b)).

phenomenon during the process.

72 Iron Ores and Iron Oxide Materials

This process was developed by the Nippon Kokan Keihin company (nowadays JFE Steel Corporation) with the objective of using fine iron-rich ores in their plants. The process is based on using pelletizing discs to obtain green pellets that are then coated with coke breeze before their disposal over the sinter strand. A commercial plant with an annual capacity of 6 million tons is working using HPS process at Fukuyama (belonging to JFE Steel Corporation) [18].
