In terms of reducibility, hydrogen is the best alternative for use as a reducing agent for reducing iron oxides. 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 a 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 installed at the Chair of Ferrous Metallurgy.

In the process, argon 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. The 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 to reduce stable metal oxides.

Stabilizing the arc is one of the main influencing parameters on the productivity of the process. Argon is used not only to decrease hydrogen concentration in the H₂-Ar mixture but also to stabilize the arc. Despite using argon as a stabilizer, stabilizing the HPSR plasma arc via an external magnetic field proved to be suitable. This study is to design and construct a system to increase the plasma arc stability via an external magnetic field from a laboratory-scale plasma facility.