Development of a new laboratory-scale reduction facility for the hydrogen plasma smelting reduction of iron ore based on a multi-electrode arc furnace concept

Abstract

Steel production accounts for a significant share of industrial CO2 emissions. The HPSR process is a possible alternative to reduce these emissions massively if not completely negate them. In principle, Fe-ore is reduced at high temperatures in the plasma of a DC electric arc. hydrogen reacts with the oxidic melt at the gas-liquid interface. Various concepts for the hydrogen plasma reduction of iron ore have been investigated, but the process technology has not yet surpassed the demonstration scale (TRL5). Experimental setups for charging masses from a few grams to a few hundred kilograms have been realized. Further investigations on the process stability and the reaction kinetics are still necessary. An improved laboratory-scale furnace concept shall provide the basis for the fundamental research. An existing laboratory facility is the starting point for designing and constructing the new plasma furnace. There are several problems with this experimental setup. Mainly, the reactor’s dimensions and power supply limitations restrict the arc’s length. The first leads to problems with excessive refractory wear, while the latter limits the variation of process parameters. Strong cooling when using Fe crucibles and the unstable nature of the arc complicate the process control. A promising concept to deal with the problem of arc stability is the use of multiple electrodes in a direct current arc furnace. Together with an optimized furnace geometry, new potential for further investigations can open. Using a multi-cathode furnace is also promising to further explore ferroalloy production via hydrogen plasma reduction. An electric arc furnace was designed based on the requirements for the planned plasma reduction facility. The energy requirement was based on assumptions for heat transfer from the arc to the melt, walls, and lid and continuous transfer through the individual furnace parts. Considerations of power supply, hearth dimensions, refractory design, controlled gas atmosphere, and the implementation of auxiliary equipment were central to creating an ideal basis for various experimental setups.