Abstract The blast furnace (BF) has been the predominant technology for producing molten iron since its invention and widespread adoption. Challenges of decarbonisation and production of direct reduced iron (DRI) from low-grade iron ore have raised the potential for incorporating electric smelting furnaces (ESFs) into the direct reduced iron-basic oxygen furnace (DRI-BOF) pathway to produce molten iron. Developed smelting technologies, such as the Submerged Arc Furnace (SAF) has been widely used in ferro-alloy production for more than 100 years. Though three ESFs are currently in operation worldwide for molten iron operation (Craig et al. in Global Low-Carbon Metallurgy Innovation Forum 2022 and the 8th Baosteel biennial academic conference, 2022; Garlick et al. in J Sustain Metall, 2025) they are not at the scale required to replace the BF operation. Open Slag Bath Furnace (OSBF), which uses “open arc” or “brush arc”, shows promise in processing low-grade DRI. It is claimed (Steinberg in Development of a control strategy for the open slag bath furnaces, Highveld Steel and Vanadium Corporation Ltd., University of Pretoria, Pretoria, 2008) that an OSBF can operate at a higher resistance (2 to 4 mΩ) compared to a SAF (1 mΩ or even below). It has also been reported ( Steinberg WS (2008) Development of a control strategy for the open slag bath furnaces at Highveld Steel and Vanadium Corporation Ltd. University of Pretoria (South Africa)) that the OSBF furnace can work in higher power level (100 MW at 3 mΩ) compared to a SAF (70 MW at 1 mΩ). Critical analysis of the literature indicates that there is a lack of independent research on OSBF furnaces. One potential major drawback of employing an open arc in OSBFs is the increased heat loss through radiation from the furnace roof, which can accelerate the wear of roof refractories and lower overall energy efficiency. This paper critically reviews the current understanding of ESF technology for ironmaking, identifies the key knowledge gaps, and proposes directions for future research. Graphical Abstract
Sabah et al. (2026) studied this question.