The global steel industry is increasing its efforts to defossilize and reduce its specific CO2 footprint. Using electrical energy to melt iron units of scrap, pig iron, direct reduced iron (DRI) and hot briquetted iron (HBI) of various mixtures and origins is beneficial to reduce the CO2 footprint but leads to new challenges. Different electric arc furnace (EAF) designs and pro-cess variants have been proven in the past decades and help to develop the EAFs of the future for higher input of DRI and HBI according to the steel quality demands. This article describes and discusses the technology options and their process realities for integrated plants.

The ZESTY Ironmaking process involves the use of Calix’s flash calcination technology to reduce iron ore fines to iron in a hydrogen atmosphere between 600 and 1,050°C. In 2022, Calix ran a series of proof-of-concept campaigns at its pilot plant facility using a range of iron ores, particle sizes, process temperatures, hydrogen flowrates at throughputs up to 100 kg/hour in semicontinuous mode. Detailed x-ray diffraction, scanning electron microscopy-
energy-dispersive x-ray spectroscopy, optical microscopy and chemical analysis of the samples revealed key aspects of the process, showing that hematite-goethite ores could be readily metallized in the process. A modified thermogravimetric technique was able to duplicate closely the kinetic behavior observed in plant trials.

Many steel producers are considering direct reduced ironmaking (DRI) with subsequent hot metal production using an electric smelting furnace (ESF) as a decarbonization strategy. Little attention has been paid to the potential reuse of car-bon-containing offgases when the DRI process is co-located with the ESF and an existing basic oxygen furnace (BOF) shop. Methanation of the CO-rich ESF and BOF offgases enables the recycling of carbon contained in these offgases back to the DRI plant as synthetic natural gas. Part 1 of this study focuses on methanation as an innovative way to use H2 without modifying the operation of the DRI plant, reducing technical risk to the steel plant operator. In Part 2, an economic assessment of the new integrated DRI-ESF-BOF process route is presented. 

Hydrogen-based direct reduction is expected to become one of the main levers to reduce CO2 emissions in future iron- and steelmaking. For melting and refining of the direct reduced iron, an electric arc furnace (EAF) is the ideal method if iron ore grade is high and resulting slag amount in the EAF is reasonably low. But as most of the iron ore globally is of lower grade and beneficiation has its limits, a new type of furnace — the Smelter — is required. Details of the Smelter as well as the road map for development are presented.