The steel industry is an important engine for sustainable growth, added value, and high-quality employment within the European Union. It is committed to reducing its CO₂ emissions due to production by up to 50% by 2030 compared to 1990′s level by developing and upscaling the technologies required to contribute to European initiatives, such as the Circular Economy Action Plan (CEAP) and the European Green Deal (EGD). The Clean Steel Partnership (CSP, a public–private partnership), which is led by the European Steel Association (EUROFER) and the European Steel Technology Platform (ESTEP), defined technological CO₂ mitigation pathways comprising carbon direct avoidance (CDA), smart carbon usage SCU), and a circular economy (CE). CE approaches ensure competitiveness through increased resource efficiency and sustainability and consist of different issues, such as the valorization of steelmaking residues (dusts, slags, sludge) for internal recycling in the steelmaking process, enhanced steel recycling (scrap use), the use of secondary carbon carriers from non-steel sectors as a reducing agent and energy source in the steelmaking process chain, and CE business models (supply chain analyses). The current paper gives an overview of different technological CE approaches as obtained in a dedicated workshop called “Resi4Future—Residue valorization in iron and steel industry: sustainable solutions for a cleaner and more competitive future Europe” that was organized by ESTEP to focus on future challenges toward the final goal of industrial deployment.

The EU steel industry accounts for a crude steel production of 140 Mt/y, provided by the integrated (57%) and electric (43%) routes, which respectively require up to 6.0 and 0.6 MWh/t_CrudeSteel of energy input, and emits on average 1.85 and 0.4 t_CO2/t_CrudeSteel. The mitigation of such CO₂ emissions is crucial, and would involve the direct avoidance of carbon, improvement of energy efficiency, and carbon capture. However, the environmental burden of the steel industry cannot be limited to this, given the very large amount (approximately 5 Mt) of residues landfilled every year in the EU. This practice cannot be sustained anymore, since it represents a detrimental waste of resources and burden to the environment. These aspects require prompt action to meet the Green Deal goals envisioned for 2030. This review paper aims to provide an overview of the main state-of-the-art technologies commercially (and not) available for the effective treatment of a wide variety of residues. To enrich this overview with further potential candidates towards a more sustainable steel manufacturing process, the combined application of two technologies (a plasma reactor and a RecoDust unit for the recovery of metals and minerals, respectively) at TRL 5-6 is also investigated here.

This paper aims at providing an overview of the ways for residue valorization in the iron and steelmaking industry. The important role of recycling in iron and steelmaking as a cornerstone for achieving a cleaner and resource-efficient potential is described. Several research results concerning metals and metal oxides (scrap, scale), slags, dusts, process gases, and water recycling from the iron and steelmaking process are reviewed here, aiming to detect those research gaps that still need implementation and suggest potential approaches toward potential solutions. Through a comprehensive evaluation, several possibilities are provided to incorporate effectively in metallurgical processes the bio-based or bio-derived carbon materials, namely biomass, biochar, biocoke, and polymers from waste plastics to reduce the dependence on fuel and reducing agents from fossil sources, and therefore mitigating the related environmental impact of the steel industry. Eventually, this review highlights the importance of embracing circular economy (CE) principles in iron and steelmaking, along with considering opportunities for industrial symbiosis (IS) and exploring the role of digitalization and digital solutions in recycling practices.

The 1.9 billion metric tons of steel globally manufactured in 2023 justify the steel industry’s pivotal role in modern society’s growth. Considering the rapid development of countries that have not fully taken part in the global market, such as Africa, steel production is expected to increase in the next decade. However, the environmental burden associated with steel manufacturing must be mitigated to achieve sustainable production, which would align with the European Green Deal pathway. Such a burden is associated both with the GHG emissions and with the solid residues arising from steel manufacturing, considering both the integrated and electrical routes. The valorisation of the main steel residues from the electrical steelmaking is the central theme of this work, referring to the steel electric manufacturing in the Dalmine case study. The investigation was carried out from two different points of view, comprising the action of a plasma electric reactor and a RecoDust unit to optimize the recovery of iron and zinc, respectively, being the two main technologies envisioned in the EU-funded research project ReMFra. This work focuses on those preliminary steps required to detect the optimal recipes to consider for such industrial units, such as thermodynamic modelling, testing the mechanical properties of the briquettes produced, and the smelting trials carried out at pilot scale. However, tests for the usability of the dusty feedstock for RecoDust are carried out, and, with the results, some recommendations for pretreatment can be made. The outcomes show the high potential of these streams for metal and mineral recovery.