Influence of the material and hydrogen injection point on the efficiency of the hydrogen plasma smelting reduction process

In an effort to reach the goals of the Paris Agreement, the steel industry is in the midst of a transformation towards renewable production methods. One of these technologies is hydrogen plasma smelting reduction (HPSR), which the Chair of Ferrous Metallurgy has researched at the Technical University of Leoben for several decades. This study examines the influence of different material charging and process gas injection methods on the efficiency of the process. Experimental trials were conducted using three distinct charging strategies: batch operation, continuous charging via a hollow graphite electrode (HGE), and feeding through self-consuming electrodes (SCE) made from iron ore. Each approach was combined with various hydrogen and argon injection configurations. These included three approaches: conjoint input via the HGE, separated gas flow via HGE and a lateral injection nozzle and conjoint lateral addition. Results indicate that the gas input has a decisive impact on the process performance, while the influence of the charging method is comparatively minor. Conjoint injection of hydrogen and argon consistently achieved higher reduction degrees and faster reduction rates than separated gas flows. In contrast, separated injections led to poorer hydrogen transport to the reaction zone and thus lower overall reduction efficiency. Average reduction rates of up to 0.85 gO2/min and hydrogen utilizations near the thermodynamic limits were achieved.