8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Hydrogen plasma smelting reduction (HPSR) is now an established alternative to be conside-red for upgrading existing ironmaking process and reducing the emission of greenhouse gases. HPSR offers thermodynamics and kinetics advantages over conventional carbo-thermic re-duction of iron ores. This process provides improved reducing conditions by the application of hydrogen in the plasma state and high temperature to intensify the reduction processes, henceforth not only enables the feasibility of producing iron in a one-stage process, but also avoids introducing carbon in the product, which in turn makes the metallurgical equipment smaller. In HPSR process, plasma is generated by passing an electric current through a mixtu-re of argon and hydrogen gases which is injected to the plasma arc zone in the reactor via the hollow graphite electrode. Electrons, which are accelerated particles, are responsible to trans-fer energy in plasma atmosphere. Electron collision with hydrogen molecules leads to create excited spieces of hydrogen (H, H+, H2+, H3+), therefor the number of free electrons in plasma state, degree of ionization and the lifetime of excited particles should be considered due to their influence on reduction reactions. Moreover, the density of the hydrogen-activated spices in plasma, which defines the ionization rate of hydrogen, is a function of temperature and the number of injected molecular hydrogen in the arc zone. This study provides an overview of the following items: 1. Atomic collisions 2. Creating plasma by collisional processes in a plasma arc reactor 3. Degree of ionization 4. The thermodynamic principles of iron oxides reduction by hydrogen 5. Comparision of the reduction ability of hydrogen species in plasma state. As a result, the reduction rate with hydrogen is two orders of magnitude faster than those with other reducing agents. In addition, hydrogen plasma smelting not only provides the most envi-ronmental friendly steel making, but also produced steel in this way is cheaper than the con-ventional steel making routes.