Hydrogen plasma smelting reduction (HPSR) of iron ore as a new generation of steelmaking is a process in which iron ore in a plasma furnace is reduced by ionized and excited hydrogen molecules. In this process, argon is used as a plasma gas due to its low ionization energy and high conductivity. Another possibility is the use of nitrogen instead of argon. Hydrogen operates as a reducing agent, hence a mixture of hydrogen and argon is injected into the arc zone in the reactor through the hollow graphite electrode. The injection through the electrode can guarantee the best conditions for atomization and ionization. In the HPSR process, colliding electrons with hydrogen molecules leads to exciting them. Hence, excited hydrogen molecules play an important role in extracting of iron from iron ores.
A lab-scale plasma reactor with relevant equipment was installed in our Plasma Arc Laboratory. The normal continuous power of the reactor is 8 kW which is supplied by a DC power unit with regard to transferred arc attachment. The below figure shows a schematic of the plasma facilities.
Figure: Schematic overview of the Plasmette
In terms of hydrogen species, it can exist in molecular H2, atomic H, ionic H+, H2+, H3+ and exited H* states. The reduction rate of iron ore in the liquid state is higher than solid state. Therefore, to evaluate the reduction rates in the HPSR process, it is essential to know the temperature gradients of the plasma arc and its influence on the temperatures of the iron ore particles in the arc zone.
- Specification of gas velocity in the plasma arc
- Specification of iron ore and lime particles velocity in the arc zone
- Modeling of temperature fields for plasma arc
- Heat transfer modeling of solid particles in the arc