Thermodynamic analysis of the reduction performance of iron oxide using H2 and CO gas mixtures Eduardo Borges Matos, Behzad Sadeghi, Pasquale Cavaliere Minerals Engineering, 2026 • 50% H2 and 50% CO optimal for different conditions. • The lower enthalpy of CO favors the initial reduction; H2 improves the later phases. • CO excels at low temperatures, H2 at high temperatures. • CaO and MgO improve the porosity and reducibility of the pellets. • H 2 processes demand more energy due to strong hydrogen–oxygen affinity. In this study, a comprehensive thermodynamic analysis of the direct reduction of iron oxide pellets was carried out, focusing on the quantitative influence of the reducing gas components (carbon monoxide, CO, and hydrogen, H 2 ) and the pellet composition (including additives such as CaO, SiO 2 and MgO). In a temperature range from 0 to 1000 °C at 1 bar pressure, the study showed a different efficiency of CO and H 2 in the reduction of iron oxides. At lower temperatures (200–600 °C), CO showed higher efficiency and achieved up to 15% higher equilibrium Fe content due to its lower enthalpy requirement and rapid reduction of Fe 2 O 3 to Fe 3 O 4 . Conversely, H 2 achieved up to 25% higher Fe reduction efficiency at higher temperatures (>700 °C), favored by its smaller molecule size and higher diffusivity, which improved gas penetration and accelerated the reduction of Fe 3 O 4 and FeO to metallic Fe. Mechanistically, the superior performance of H 2 at elevated temperatures is due to its higher affinity for oxygen and the improved diffusion rates that overcome the endothermic nature of the reduction process. Furthermore, the addition of CaO and MgO improved the reducibility of the pellets by modifying the porous structure, lowering the activation energy and increasing the gas permeability. Conversely, SiO 2 hindered the reduction by forming stable fayalite (Fe 2 SiO 4 ), which increased the enthalpy requirement. These results quantitatively explain the temperature-dependent role of the reducing gas components and the mechanisms underlying their effects. They provide a basis for optimizing gas composition and pellet designs to improve energy efficiency and environmental performance in industrial direct reduction processes.
Closed-loop extraction of precious metals from e-waste via NH4HCO3 desulfurization and secondary lead smelting Behzad Sadeghi, Sai Nikhil Allam, Afshin Khazaei, Pasquale Cavaliere Waste Management, 2026 • We integrated battery lead recycling with precious metal recovery from e-waste. • Ammonium bicarbonate achieved up to 97% sulfur removal. • High-purity lead (∼99 %) was recovered rapidly with reduced energy input. • Molten lead effectively collected gold and other metals from e-waste. • We offer eco-friendly alternative to chemical-intensive recycling methods. This study presents a novel, eco-friendly metallurgical process that integrates battery recycling with e-waste precious metal extraction in a single closed-loop system. The method uniquely combines ammonium bicarbonate‐based desulfurization of spent lead–acid battery paste, secondary lead (Pb) smelting, and Parkes process refining for precious metals extraction. Ammonium bicarbonate (NH 4 HCO 3 ) achieved a sulfur removal efficiency of up to 97%, which is comparable to or higher than many conventional reagents such as NaOH and Na 2 CO 3 , under similar conditions. The desulfurized paste was then smelted (with coal as reductant and soda ash flux) to produce high-purity lead metal (∼98–99% Pb), which served as a liquid collector for gold, silver, and palladium from e-waste. Subsequently, the Parkes process (zinc alloying) was applied to selectively separate these precious metals into a Zn-rich phase. The integrated process was validated under various conditions; XRF analyses and theoretical modeling confirmed consistent extraction of lead and precious metals. For the first time, this work demonstrates a continuous closed-loop Pb metallurgy route capable of simultaneously processing battery waste and e-waste. The results show that the process is scalable, adaptable to different feedstocks, and efficient in both sulfur removal and precious metal extraction offering a practical, sustainable alternative to conventional fragmented or chemical-intensive recycling methods.
Barriers to Steel Decarbonization Pasquale Cavaliere Steel Research International, 2026 Carbon dioxide (CO 2 ) emissions are a leading contributor to global climate change, necessitating urgent mitigation strategies. While various metrics—such as total national emissions, per‐capita output, and historical contributions—define responsibility, determining accountability remains complex. Historically, emissions were minimal before the Industrial Revolution, but fossil fuel combustion has triggered an exponential rise in CO 2 levels since the mid‐20th century. The geographic distribution of emissions has shifted over time. The United States and Europe dominated emissions throughout the 20th century, but Asia's industrial expansion has altered global patterns. China now leads in emissions, followed by the United States and the European Union, with per‐capita outputs differing significantly across regions. Fossil fuel combustion, particularly through coal, oil, and natural gas, remains the primary source of emissions, with the energy sector alone contributing approximately 40% of global CO 2 output. In response, the renewable energy market has expanded, with nations setting ambitious decarbonization targets through investments in solar, wind, hydropower, and other clean technologies. Steel production is a key contributor to industrial emissions, with conventional blast furnace–basic oxygen furnace (BF–BOF) methods dominating global output. However, sustainability concerns have accelerated the shift toward electric arc furnace (EAF) technology and direct reduced iron (DRI) integration, which offer efficiency benefits and lower emissions. Despite efforts to decarbonize, the iron and steel sector continues to rely heavily on coal, complicating global climate goals. This industry accounts for 11% of global CO 2 emissions, making net‐zero commitments crucial for long‐term environmental sustainability. Major steel manufacturers have pledged to reduce emissions, with technological innovations such as hydrogen‐based production and carbon capture playing a vital role. Projects like SSAB's HYBRIT initiative highlight the feasibility of fossil‐free steel production, but economic, technological, and logistical challenges remain. Investment in infrastructure, electrolyzer technology, and hydrogen storage solutions is necessary to ensure long‐term viability. Policy interventions, including financial incentives and regulatory frameworks, will be critical in scaling green steel initiatives. The transition to low‐emission steelmaking requires collaboration across industries, technological innovation, and supportive policy frameworks. Nations worldwide are adopting various decarbonization strategies, prioritizing electric arc furnace (EAF) expansion, DRI integration, and the retrofitting of existing BFs. Hydrogen‐based steel production presents unique challenges but offers a pathway to achieving net‐zero emissions in the sector.
Modeling the Thermal Properties of Hydrogen-Based Direct Reduced Iron Using Computational Thermodynamics and Machine Learning Ankur Agnihotri, Petri Sulasalmi, Pasquale Cavaliere, Ville‐Valtteri Visuri Steel Research International, 2026 Hydrogen‐based direct reduced iron (H‐DRI) is a promising low‐carbon feedstock for steelmaking using electric‐arc‐furnace (EAF) or electric smelter (ESF). So far, the information on the thermal properties of H‐DRI, which is crucial for predicting the energy need and melting time, is limited. In this study, we investigated H‐DRI pellets with varying metallization levels (68%, 86%, 90%, and 95%) and measured thermal response using differential scanning calorimetry (DSC) up to 1600°C to determine the solidus and liquidus temperatures as well as the heat capacity and enthalpy of melting. The composition of the pellets with respect to bulk oxides (Fe, SiO 2 , Al 2 O 3 , CaO, FeO, MnO) was measured by X‐ray fluorescence (XRF) and used in FactSage 8.3 (FactPS, FToxid, FTmisc) to compute reference values for specific heat capacity, enthalpy, and phase transition temperatures. The melting points calculated using FactSage matched DSC results within about 15°C; calculated enthalpies were within ≈5%, and specific heat capacities within about 3%. To account for variability, we generated 1000 synthetic chemistries covering industrial ranges (55–97 wt% Fe, 2–10 wt% SiO 2 , 1–8 wt% CaO, 0–25 wt% FeO, 0–5 wt% Al 2 O 3 , 0–5 wt% MnO), split into 80/20 for training and validation. Simple linear regressions predicting solidus and liquidus temperatures from composition explained over 96% of the variance on held‐out data, while specific heat capacity and enthalpy were calculated via Shomate mass‐fraction mixing and validated against DSC and FactSage. Independent tests on four H‐DRI samples fell within the experimental uncertainty. These relations enable routine XRF analyses to determine melting temperatures and thermophysical properties quickly and reliably, simplifying heat‐balance calculations in the modeling and operation of the EAF.
Physics-Constrained Constitutive Learning of Rate-Limiting Timescales for Efficient Hydrogen-Based Direct Reduction for Green Steel Making Anurag Bajpai, Barak Ratzker, Pasquale Cavaliere, Dierk Raabe Advanced Science, 2026 Hydrogen‐based direct‐reduction enables carbon‐neutral primary ironmaking, yet widespread industrial adoption is constrained by sluggish late‐stage kinetics, which lower production efficiency and increase energy and hydrogen consumption. Here, we develop a conversion‐resolved constitutive framework that infers effective reaction and transport timescales directly from measured reduction trajectories and maps their constitutive dependence on operating conditions, pellet architecture, and composition. The scientifically constrained additive model (SCAM) framework is then used to convert these trajectory‐inferred timescales into interpretable constitutive maps, symbolic laws, and regime boundaries across variations in processing conditions and pellet microstructure/composition. We find that internal diffusion accounts for most of the incremental reduction time at intermediate to high conversion percentages, and the reaction‐to‐diffusion control boundary shifts systematically with conversion progression and evolving porous microstructure. Temperature and hydrogen partial pressure mainly accelerate early‐stage conversion rates, whereas the late‐stage conversion rates are governed by the pellet‐to‐pore length scale, average porosity, and tortuosity. Pellet composition primarily affects the late‐stage diffusion‐controlled regime through its influence on pore‐morphology descriptors, while a residual effect persists in the reaction‐controlled regime. The resulting regime maps and symbolic laws yield experimentally anchored pellet‐scale constitutive relations to identify reduction‐stage‐specific rate‐limitations and guide industrial pellet design, thereby providing actionable guidelines for more efficient green steelmaking.
Determining of iron oxide pellet porosity using image analysis and its effect on the reduction behavior Eduardo Borges Matos, Tero Vuolio, Timo Fabritius, Pasquale Cavaliere, Maycon Athayde Materiaux Et Techniques, 2026 Hydrogen-based reduction of iron oxide is a promising new technology in fossil-free steelmaking. In the process, the iron oxide is usually fed in a form of spherical pellets or briquettes. In solid-gas-reactions, the porosity of the pellets is assumed to enhance the reduction kinetics via the increase of the available reaction surface area at the reaction interface. However, the multivariable and complex dynamics of the reduction system complicates the estimation of this effect, as it is known that the properties of the pellet evolve withing the progression of the reduction. In the kinetic analysis procedure, determining the pellet porosity is a demanding task. Measuring the porosity of the pellets is commonly performed using tomography analyses. However, image analysis of X-Ray tomography images of pellet cross-section could provide more practical approach as faster method. In this study, a sophisticated image analysis procedure is developed to analyze the pellets and briquettes porosity based on cross-section images. It was found that the porosity based on image analysis correlates reasonably well with the tomography analysis, with the average percentage error between both approaches being 4.3%. In addition, the effect of cross-sectional porosity on the reduction rate of the pellets is analyzed by making use of kinetic analysis.
Dielectric Properties and Microwave Reduction Behavior of BOF Slag and Lignin Mixture Danuka Maduranga Wawita Widanalage Don, Timo Fabritius, Pasquale Cavaliere, Eetu-Pekka Heikkinen, Aidin Heidari, José M. Catalá-Civera, Pedro J. Plaza-González, Mamdouh Omran Metallurgical and Materials Transactions B Process Metallurgy and Materials Processing Science, 2026 Basic oxygen furnace (BOF) slag is the second highest byproduct generated in the European steel industry. In this study, the reduction behavior of BOF slag mixed with lignin, a byproduct of paper-pulp and bioethanol industries, under microwave heating was investigated. The microwave dielectric properties of a BOF slag-lignin mixture were measured under intense microwave electric fields. The microwave reduction experiments were carried out at 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C temperatures, for 10 minutes, under an inert N 2(g) atmosphere. The microwave reduction results were compared with TGA reduction experiments conducted at the same temperatures. The dielectric properties showed that BOF slag can be heated under microwave efficiently due to its high permittivity and loss tangent values. The microwave reduction of BOF slag results indicated that increasing temperature leads to increase the reduction of srebrodolskite (main iron-bearing phase of BOF slag) to metallic iron, at 800 °C temperature, srebrodolskite completely reduced to iron metal under microwave energy. TGA results showed that srebrodolskite not fully reduced into iron metal event at 1000 °C. This indicates efficient reduction of BOF slag at lower temperature under microwave heating.
CO2Emission Reduction in Blast Furnaces Pasquale Cavaliere, Alessio Silvello Ironmaking and Steelmaking Processes Greenhouse Emissions Control and Reduction, 2016
Productivity and dioxins reduction analysis during sintering ore operations 6th Int Congress on the Science and Technology of Ironmaking 2012 Icsti 2012 Including Proceedings from the 42nd Ironmaking and Raw Materials Seminar and the 13th Brazilian Symp on Iron Ore, 2012
