Hydrogen, in terms of reducibility, is the best alternative for use as a reducing agent for the reduction of iron oxides. In fact, hydrogen plasma smelting reduction (HPSR) is a new “CO2”-free steelmaking process in which iron oxides are reduced by hydrogen in the plasma state. In HPSR, plasma is generated by creating an electric arc between a hollow graphite electrode as the cathode and molten iron oxide bath as the anode, with continual input of a mixed gas containing argon and hydrogen. Figure 1 shows the basic flow sheet of the plasma experimental equipment which was installed at the Chair of Ferrous Metallurgy.
Figure 1 Laboratory-scale plasma facility at the Chair of Ferrous Metallurgy.
In the process, argon or nitrogen is used to conduct the current in the plasma arc; argon is preferred due to its low ionization energy and high conductivity. Hydrogen operates as the reducing agent; hence, a mixture of hydrogen and argon is injected into the arc zone in the reactor through the hollow graphite electrode. Collision of electrons with hydrogen molecules at high temperatures leads to the activation of the hydrogen molecules. The injection of gases through the electrode directly to the arc zone guarantees optimal conditions for atomization and ionization. Excited hydrogen molecules provide a potentially very useful way for the reduction of stable metal oxides.
Iron ore fine is poured in the steel crucible with the maximum capacity of 200 g. the weight of the sample influences the reduction rate of the iron ore. Therefore, this study is to evaluate the effect of sample weight on the reduction rate of iron oxide. The other possibility is to feed iron ore powder by a powder feeder. Then, the feeding rates is the other parameter that should be assessed in terms of the reduction rates.
- Literature study
- Preparation of the experimental program with different iron ore feeding rates for continuous feeding, and different weight of iron ore in the crucible for the batch trials
- Kinetics of the iron ore reduction by hydrogen plasma
- Definition of the optimum weight of iron ore for the batch operations and optimum iron ore feeding rates for the continuous operations