CO₂ Ultimate Reduction System for Cool Earth 50 (COURSE50) successfully carried out operational trials with an experimental blast furnace in which the effect of the reaction-control by COG injection, top gas recycling, and use of high reducibility sinter on the carbon rate were determined. The conditions of the operational trials were designed by applying the mathematical blast furnace model that was developed. The results obtained in the operational trials indicate that the proportion of carbon direct reduction can be decreased while maintaining that of CO reduction, by the reaction-control by COG injection, top gas recycling, and use of high reducibility sinter. A reduction in the carbon rate of approximately 10% was achieved as predicted by the mathematical blast furnace model.

COURSE50, CO₂ Ultimate Reduction System by Innovative technology for cool Earth 50, is the national project for reduction of CO₂ emission from steelworks in Japan. Three steel companies and one engineering company join this project supported by NEDO (New Energy and industrial technology Development Organization). The target of COURSE50 is reduction of CO₂ emission from steel works over 30%, 20% by CCS (Carbon Capture and Storage) and 10% over by operation of blast furnace. In order to realize the reduction of CO₂ emission form blast furnace over 10%, H₂ utilization technology has been developing using 12 m³ experimental blast furnace. The experiments have been taking place form 2016. From 2016 to 2017, 10% reduction of CO₂ emission achieved by using three methods, gaseous reductant injection from tuyeres, gaseous reductant injection from shaft tuyeres, and high reducibility sinter charging. In order to improve the reduction CO₂ emission technology, hydrogen-based gaseous reductants were used form 2018. Five campaigns were taken placed from 2018 to 2020. An unprecedented amount of H₂ gas in the world was injected in the experimental blast furnace. As a result, it is clarified that direct reduction rate was fell and H₂ reduction rate was raised straightly as amount of H₂ input was increased. Also, the reduction rate of CO₂ emission was affected by the amount of hydrogen injection. About 16% of CO₂ emission was reduced with 359 Nm³/t-HM of H₂ injection.

Amine based adsorbents are promising options for CO₂ removal from industrial exhaust streams because they offer low regeneration energy and high CO₂ capture performance. Tetraethylenepentamine (TEPA) is one of the most common commercial polyamines that has been used as a prototypical amine to develop effective amine based adsorbents for CO₂ capture. For the viability of carbon capture based on amine adsorbents, the durability of amine sites during practical applications is an important criterion. This work focused on the stability of TEPA based materials under accelerated oxidizing conditions in the presence of O₂, SO₂, NO₂, water vapor, and simulated flue gas. It was found that the presence of gas impurities caused a marked loss of the CO₂ adsorption capacity of the adsorbents. The presence of water vapor and CO₂ suppressed oxidative degradation of the adsorbents.

Roughly 10% of the CO₂ emissions from iron and steel making are attributable to the direct release of CO₂ from the thermal decomposition of carbonates to produce flux, mainly CaO, used for impurity removal. Notably, these direct emissions remain even if carbon-based steelmaking is replaced by hydrogen-based steelmaking. After removing impurities from the molten metal, this flux becomes the solid waste product called ‘slag’, a primarily Ca-silicate material. The transformation of slag back into carbonates is thermodynamically spontaneous with negative ΔG in the ambient environment, meaning that ~10% of the CO₂ emissions from iron and steel making could be negated if equipment and methods were developed to support CO₂ mineralization. However, the rate of CO₂ mineralization using slag is slowed by several environmental, geometric, and processing factors. We leverage an experimentally verified model of CO₂ mineralization to determine how to efficiently accelerate the process. Increasing the crystallinity of slag, increasing the relative humidity, and reducing the grain size of slag particles provide the greatest increase in CO₂ mineralization rate at the lowest energy penalty. Increasing the concentration of CO₂ and the temperature provide only modest increases in the CO₂ mineralization rate while incurring a substantial energy penalty. For steelmaking slags, CO₂ mineralization represents low-hanging fruit as the current reuse pathways are low value. For ironmaking slag, replacing the production of amorphous slag for the cement industry with the production of crystalline slag for CO₂ mineralization becomes financially preferable when a carbon price/tax exceeds 67.40 USD/t-CO₂.

In the last years, the injection of reducing gases in the shaft and preparation zone of the blast furnace has been proposed as a decarbonization option, mainly associated to oxyfuel blast furnaces and top gas recycling configurations. However, the Rist diagram, which is one of the preferred methodologies to characterize the operation of blast furnaces, is not valid to evaluate these new decarbonization options. In this article we propose a generalization of the operating line methodology to extend its applicability to scenarios of variable molar flows along the blast furnace (i.e., shaft and preheating injections) and non-continuous oxidation profiles (presence of CO₂ and H₂O in the injected gases). The extended operating line methodology was implemented in an Aspen Plus simulation, which provides a detailed modelling of the preparation zone, the thermal reserve zone, the lower zone and the raceways. The simulation was used to validate the generalized operating line methodology through three different data sets: (i) an air-blown blast furnace with pulverized coal injection and O₂ enrichment, (ii) an oxyfuel blast furnace with shaft gas injection, and (iii) an oxyfuel blast furnace with preheating gas injection in the preparation zone. In general, the discrepancy between the reference data and the simulation results is well below 3.5%, so the extended operating line methodology is considered validated.

Oxalic acid has been identified as a sustainable chemical enabling an efficient recovery of target metals from industrial minerals by dissolution. The dissolution process recently has attracted attention as a key reaction in a potential clean iron-making. In this application to efficiently produce a high-purity iron, the dissolution is required to occur in the absence of light, with no addition of other chemical reagents, and to produce high concentration iron oxalate aqueous solution as fast as possible. To reveal the chemistry of iron oxide dissolution for this application, in the present study, the dissolution experiments are carried out under various conditions with a particular focus on the iron oxide highly loaded in the oxalic acid aqueous solution. Highly acidic oxalic acid solution for dissolving the highly loaded iron oxide enabled the production of iron oxalates aqueous solution with the concentration of up to 0.56 mol-Fe/L. Different from conventional studies under diluted conditions with pH control, the dissolution followed a non-reductive mechanism, producing [Fe³⁺HC₂O₄]²⁺ as a dominant iron species, and highly correlated with a concentration of proton in the solution. The experimental results and proposed stoichiometries identified a minimum amount of oxalic acid required for the complete dissolution of iron oxide independently from the concentration and type of loaded iron oxide. Among iron oxides tested (α-Fe₂O₃, FeOOH and Fe₃O₄) as the feedstock, Fe₃O₄ had an advantage in the dissolution rate, but showed a relatively low iron recovery in the solution (80–90%) because of an unavoidable formation of FeC₂O₄·2H₂O precipitates.

Oxalic acid is an attractive chemical platform potentially available from CO₂ due to its established applications and chemical characteristics enabling it to serve as a mediator in hydrometallurgy including iron-making. However, a method for synthesizing oxalic acid from CO₂ has yet to be established. In the present work, the formation of oxalate scaffold during heating of cesium carbonate (Cs₂CO₃) in the presence of CO₂ and H₂ as reactants was experimentally investigated with a particular focus on the influence of supporting Cs₂CO₃ over porous materials. Among the support materials examined, activated carbon (AC) had a notable effect in improving the reaction rate and yield of total carboxylates (formate and oxalate) during experiments with an autoclave. An important problem was the dominant presence of formate, the intermediate between carbonate and oxalate, accounting for over 90% of the carboxylates. Changing the reaction conditions, including temperature, reaction time, partial pressure of gas components, and amount of loaded Cs₂CO₃, did not alter the situation. Alternatively, re-heating of the formate-rich salts over AC under CO and CO₂ enhanced the oxalate fraction while maintaining the total carboxylates yield. Benefiting from the employment of support material, the two-step conversion was carried out using a gas-flow type reactor with a packed bed of Cs₂CO₃ supported over AC. In this reaction system, because water, acting as a promoter, was absent, the total carboxylates yield was lower than that in the autoclave, while the oxalate fraction was higher, being 71.8% with a yield of 43.2% on a Cs₂CO₃-carbon basis.

As one of the hydrogen carriers, ammonia has become one promising candidate as a reducing agent for implementing hydrogen-based ironmaking to reduce CO₂ emissions. On the other hand, the abundant high combined water (CW) iron ore has recently been investigated as a raw material for ironmaking. Goethite (FeOOH), the main component of high-CW iron ore, can change to porous hematite (Fe₂O₃) by dehydration, enhancing its reactivity. This paper describes the fundamental study of the ore reduction behavior using ammonia as reducing agent. The effects of different ore types (i.e., high- and low-CW ores), reduction temperatures (i.e., 650, 700, and 750°C), and conditions of post-reduction treatments (i.e., quenching by NH₃, fast- and slow- quenching by inert gas) on ore reduction behavior. The results reveal that the dehydrated high-CW one exhibits a higher ammonia utilization rate and is reduced faster due to the high specific surface area of the pores generated from the ore dehydration. The reduction degree of the sample increased at a higher temperature. However, in contrast, the nitriding degree decreases since the decomposition of nitrides occur highly at elevated temperatures. During quenching at temperatures lower than 700°C, the metallic Fe in the sample was nitrided in the presence of NH₃. In contrast, the nitrides were easily decomposed into metallic Fe in the absence of NH₃ at 700°C. This finding suggests that the quenching conditions significantly affect the generated phases. Thus, the generated phases of the reduced ore could be easily controlled in the post-reduction process.

The iron and steel industries currently face the depletion of high-grade ore and high CO₂ emissions. Some initiatives that effectively utilize alternative carbon sources and abundant low-grade ores become the preferable solutions. This novel study aims to utilize municipal solid waste (MSW) as a reducing agent in ironmaking using low-grade (goethite) ores. As an initial fundamental approach, the comparison of decomposition behaviors between the model and actual MSW was investigated in thermogravimetric analysis. Both model and actual MSWs mainly decompose at 300–500°C. As for reduction tests, pellets containing MSWs and ores with different pretreatments were prepared. The pellets were reduced in an Ar atmosphere at different temperatures. The effect of different ores: high-grade and low-grade ones, on the decomposition of MSW and the iron reduction, were investigated. As a result, interestingly, the low-grade, goethite ore-containing pellet exhibits a more significant reduction degree than the high-grade ones. The reduction is completed in 5 minutes at 700°C and above, indicating a significant reduction by the decomposed carbon. The reduction degree extends at elevated temperature, which reaches more than 94% at 900°C.

This study explored the possibility of using upgraded coal and coke from Indonesian lignite in the ironmaking process, specifically pulverized coal Injection (hereafter, “PCI”) coal and carbon composite pellets and carbon material (sintering binder carbon material). The study found that (1) injection of upgraded coal into the blast furnace will have the same effect as the injection of lime - heavy oil slurry into the blast furnace, the combined infusion of highly volatile matter and low ash coal, and flash pyrolysis.

(2) The sintering with lignite coke is thought to have the same effect as low temperature sintering type sintering operation. (3) The manufacture of reducing pellets using upgraded coal acts to use carbon material with high volatile matter content in the reduction of carbon composite iron.

The hot strength of coke prepared from an acid-washed lignite by briquetting-carbonization before and after CO₂ gasification was, for the first time, investigated in this work. The hot strength at 1000°C before gasification was higher than coke strength measured at a room temperature. CO₂ gasification resulted in a linear decrease of the hot strength with the reaction time. The lignite-coke showed faster decrease in the strength during gasification, compared to conventional cokes derived from caking coal or non-or slightly caking coal, due to the high reactivity caused by its porous structure and catalytic metal species remaining even after the acid-washing, while it showed superior hot strength at the initial stage of gasification.

The swelling of a packed bed of coal during carbonization was numerically investigated. The coal particles were assumed to be spheres capable of swelling. When falling particles of the same size, the height of the packed bed was determined by the particle size, and during swelling of particles of the same size, the height of the packed bed was also determined by the particle size. However, the height of the packed bed with different particle sizes was lower than that of the packed bed with particles of the same size. This was owing to the densifying of the smaller particles between the larger particles. When the swelling ratio of the particles in the differently packed beds was 25%, no difference in dilatation was observed. By fitting the numerical solutions and previous experimental data, the difference in the swelling ratio between the smaller and larger particles was 16.8%.

Approximately 60–70% of the direct greenhouse gas emissions in electric arc furnace (EAF) steelmaking originate from the use of fossil carbon charge during melting of steel scrap. Regarding short-term solutions to mitigate the climate impact of steelmaking, there is greater potential to replace fossil carbon charge with renewable carbon in the EAF than in integrated blast furnace steelmaking where mechanical strength requirements on carbon charge are too demanding. Therefore, the present study aims to provide an experimental and practical foundation for using renewable biochar in the EAF as a relatively simple step to decrease the climate impact of steelmaking.

In order to evaluate the inherent performance of biochar as a carburizing agent, lab-scale tests where completed using four different types of carbonaceous materials: synthetic graphite, anthracite coal and two types of biochar from woody biomass (BC1 and BC2). The first order dissolution rate constants from experiments ranged between 0.7 to 1.9 × 10⁻⁴ m/s, which agrees well with previously reported results. Furthermore, lab-scale results show that biochar properties commonly seen as detrimental, such as low carbon crystallinity and high porosity, do not necessarily constitute a disadvantage for biochar utilization as carburizer in steelmaking.

In order to further assess the results from lab-scale tests, an industrial trial including six consecutive heats was performed in a 50 t EAF at the Höganäs Halmstad Plant. Results show that 33% substitution of standard Anthracite carbon charge with biochar BC2 gave no deviation from normal operating conditions in the EAF.

To establish a low-carbon society, it is necessary to break away from dependence on fossil fuels, and the utilization of geothermal energy/waste heat is one of the key methods. When using geothermal energy, the rate of heat transfer decreases with time due to the precipitation of scale on the heat transfer surface, and periodic maintenance is required. Therefore, the running cost of utilizing geothermal energy is high. We focused on a rotary heat exchanger consisting of a rotating cylinder as the heat transfer wall and a fixed blade attached to the rotating cylinder for scraping the heat transfer surface. In this study, the heat recovery characteristic from chloride hot spring was experimentally evaluated. The results showed that scale formation on the heat transfer surface could be suppressed and the heat transfer characteristics could be maintained for one month.

Desiccant humidity control systems have been garnering considerable attention in the attempt to achieve highly efficient utilization of low-temperature heat exhausted from various industries at temperatures less than 373 K. We have focused on thermosensitive polymers as new desiccants because a large amount of dehumidified water would be expected in the system because of their thermosensitivity. Our previous study focused on the water adsorption behavior of poly(N-isopropylacrylamide) (poly(NIPA)), which has a low critical solution temperature (LCST) of 306 K. In this study, poly(N-isopropylmethacrylamide) (poly(NIPMA)) and poly(2-(dimethylamino)ethyl methacrylate) (poly(DMAEMA)) cross-linked with N,N′-methylenebisacrylamide (MBAA) were investigated. These polymers are known to exhibit thermosensitivity in the temperature range of 313–319 K in water, which is a higher LCST than that of poly(NIPA). Poly(NIPMA) adsorbed water vapor linearly with increasing relative humidity. It was also observed that poly(NIPMA) prepared at MBAA concentrations of 200 mol/m³ exhibited a thermosensitivity in the temperature range of 303–313 K in water vapor adsorption. Meanwhile, poly(DMAEMA) adsorbed little water vapor up to a relative humidity (RH) of 40%; however, it exponentially adsorbed water at RH levels higher than 40%. From the estimation results of effective water adsorptivity, we found that poly(DMAEMA) is applicable in desiccant humidity control systems when the dehumidification process is performed at high RH.

Thermochemical energy storage (TcES) is a promising technology for advanced energy storage. This study investigated the reaction of magnesium chloride (MgCl₂) and ammonia (NH₃) as TcES material at approximately 100°C. Activation through NH₃ absorption and desorption was confirmed to increase MgCl₂ surface area from 2.60 to 73.3 m² g⁻¹ and create mesopores. Superior NH₃ absorption reactivity was demonstrated with a maximum absorption rate of 0.019 mol_NH3 mol_MgCl2⁻¹ s⁻¹ at 100°C under 100 kPa of NH₃, compared to a nonactivated pure MgCl₂ material. In a cyclic experiment at 100°C, the activated sample achieved high energy densities and maximum thermal output/storage rates of 1720 kJ kg_Mg(NH3)2Cl2⁻¹, and 9.6 and 3.3 kW kg_Mg(NH3)2Cl2⁻¹ on the 15th cycle. Using a cyclic chemical heat pump (CHP), a high energy density of over 1600 kJ kg_Mg(NH3)2Cl2⁻¹ was achieved, demonstrating enough potential for CHP utilization of heat transformation from 90–120°C.

Mg(OH)₂ is a chemical heat storage material suitable for the utilization of unused heat at 300–400°C. It has been reported that the addition of Li compounds to Mg(OH)₂ promotes the dehydration of Mg(OH)₂. However, the demand for Li compounds has increased in recent years and the price of Li compounds is relatively high. Therefore, the purpose of this study is to enhance the dehydration reactivity of Mg(OH)₂ with a small amount of Li. In this study, several alkali metal chlorides and hydroxides such as LiCl and NaOH or KOH were added to Mg(OH)₂, and the dehydration reactivity and composition of the corresponding mixtures were investigated. The samples prepared using 5 mol% LiCl and 10 mol% NaOH (LiCl-5NaOH-10) or 2.5 mol% KOH (LiCl-5KOH-2.5) showed excellent dehydration reactivity and were dehydrated below 300°C with comparatively lower amounts of Li compounds than those reported in previous studies. These results indicate that these samples have great potential as low-cost chemical heat storage materials. However, the stabilities of these samples in air are quite different. Based on X-ray diffraction analysis of the data, the results are associated with the composition of Cl⁻, OH⁻, Li⁺, Na⁺, and K⁺.

The generation of electrical power from photovoltaics and wind energies is often mismatched with the demand of energy scheduled by industrial processes. Chemical heat storage technology allows the conversion of heat from electricity surplus, solar heat or industrial waste heat into chemical energy, which can be reutilized on-demand, either for industrial processes requiring heat or for re-conversion into electricity. This energy buffer technology would contribute in stabilizing the mismatch between demand and offer and improve the resilience of energy supply into the decarbonized Society. A main bottleneck for practical utilization of chemical heat storage is related to the poor heat transfer ability in the packed bed reactor. In this work it is tried to clarify numerically the effects of thermal conductivity and thermal contact conductance on the exergy efficiency of heat transfer during the dehydration reaction (heat storage mode). A fixed packed bed reactor with flat geometry based on Ca(OH)₂ dehydration has been considered: chemical heat storage performance indicators like average heat storage rate and exergy efficiency were obtained via numerical simulations by changing the values of thermal conductivity of packed bed’s material, thermal contact conductance between packed bed and reactor’s wall and size of the packed bed. It was found that thermal conductivity enhancement is necessary but not sufficient for achieving the highest average heat storage rate, thermal contact conductance results important for maximizing the benefits of thermal conductivity enhancement, while a decrease of size of the packed bed results beneficial for achieving higher exergy efficiencies.

To achieve high energy efficiency and CO₂ reduction during iron- and steelmaking, thermal management is vital. Use of phase change material (PCMs) to store excess energy in the form of latent heat has the potential to realize excellent thermal management. Microencapsulated PCMs (MEPCMs) consisting of an alloy PCM core and an oxide coating have improved corrosion resistance and are easy to mix with other materials. Conventionally, composite PCM pellets are fabricated by mixing glass frit (to aid sintering) with Al–25 mass% Si MEPCM. However, this process has not yet been optimized. In this study, the optimal stoichiometry of composite PCMs prepared using Al–25 mass% Si MEPCM and glass frit was investigated. The pellets were prepared by mixing with glass frit at 60, 80 and 90 mass% of MEPCM, followed by molding and heat treatment. As a result, pellets were successfully fabricated with condition including 60 and 80 mass% of MEPCM. The latent heat capacity of the composite PCM was 146 J g^–1, which was at least 1.59 times higher than that of existing sensible heat storage (SHS) materials. Moreover, the composite PCMs withstood 300 melting and solidification cycles. In summary, composite PCMs with excellent latent heat capacity and durability were successfully prepared.

A new carbonizing and pulverizing process of woody biomass has been proposed, which utilizes sensible heat of industrial flue gas using a heat storage material (HSM). In the present study, Fe–Mn–C alloy was examined as a candidate of HSM, however, it has rather poor high-temperature oxidation resistance and therefore its aluminizing treatment was attempted to solve this problem. The Al-rich layer growth and alumina formation behaviors on the Fe–Mn–C alloy during aluminizing treatment using the pack cementation method were studied. Alloy samples were aluminized at 700–900°C for 3–12 h. Change in the sample weight was measured using a TG at 1000°C for 24 h in air.

FeAl layer formed in the early stage of aluminizing, followed by Fe₂Al₅ layer formation. Acicular FeAl₂ phase precipitates in the FeAl layer. The sample aluminized at 700°C for 12 h does not have sufficient oxidation resistance, whereas ones aluminized at 800°C for 12 h and 900°C for 3–12 h show superior oxidation resistance. Continuous Al₂O₃ layer is formed due to presence of FeAl₂ or Fe₂Al₅ in Al-rich layer.

High-temperature pressure swing adsorption (HT-PSA) is a promising energy-saving approach for oxygen production from air. Ca₂AlMnO_5+δ, a Brownmillerite-type perovskite, is a promising sorbent for HT-PSA because of its remarkably high oxygen storage capacity (up to 3.3 wt%). In this study, we investigated the redox thermodynamics of Ca₂AlMnO_5+δ by pressure–composition–temperature (PCT) measurements and investigated the HT-PSA performance of Ca₂AlMnO_5+δ pellets in a 100 g-scale packed-bed-type reactor. PCT measurements revealed that Ca₂AlMnO_5+δ can reversibly separate 2.2 wt% of oxygen per cycle under equilibrium conditions between ambient oxygen partial pressure and 5×10⁻⁴ MPa at 525°C. However, in a 5 min switching HT-PSA test, Ca₂AlMnO_5+δ pellets were able to reversibly separate less than 1 wt% oxygen per cycle, which is significantly lower than that estimated from the thermodynamic properties of Ca₂AlMnO_5+δ. On the other hand, the exothermic oxygen storage and endothermic oxygen release reactions cause significant temperature variation of the packed bed. This study clarifies that, in order to increase the energy efficiency of oxygen separation by HT-PSA, there is a need to compensate for the heat of reaction, which changes the reactor temperature in a direction that interferes with the reaction.

Sinter plants account for more than 10, 40 and 70% of the total emission of CO₂, NO and SO₂ in steelworks, respectively. It is necessary to reduce the fuel ratio in the sinter mix to decrease the CO₂ emission from sinter plants, which will harmfully affect on the melt formation and sinter quality consequently. To overcome the loss in the amount of melt, the current study aims to clarify the effect of adding iron ores-based calcium ferrites to the sinter mix on the sinter quality and emission of harmful gases. The addition of calcium ferrites promoted a significant drop in the sintering temperature, while maintaining the porosity level. The presence of calcium ferrites led to the formation of finer pores, modifying the dominant pore size in the sinter from macro to medium/micropores. The amount of SFCA and SFCA-I phases was significantly increased from 9% of the standard sinter to at least 32%. The sinter properties such as reduction degree, RI and RDI were improved in the presence of calcium ferrites by at least 24, 74 and 26%, respectively. Due to the decrease in the sintering temperature, the required fuel ratio is expected to decrease by more than 30%, and consequently the identical reduction ratio was resulted in the emission of CO₂. The presence of calcium ferrites also contributed to the reduction in the emission of NO and SO₂ at least by 38 and 49%, respectively. A low-temperature sintering process could be designed by adding calcium ferrites to the sinter mix.

Regarding the depletion of high-grade iron ore and an increase in steel scrap, a new ironmaking process that can utilize both low-grade iron ores and steel scraps is expected. When steel scrap is used as an iron source, tramp elements, such as Cu and Sn, are dissolved in hot metal. The tramp elements can affect the hot metal composition due to the thermodynamic interaction between tramp elements and other alloying elements. However, the thermodynamic interaction between Cu and Sn with Mn has not been known enough. In this work, the interaction coefficients between Cu and Sn with Mn were measured at 1873 K by a chemical equilibration technique using the liquid immiscibility of Fe and Ag as follows:

Moreover, the effects of scrap ratio (iron mass ratio of scrap to scrap and sinter) on hot metal and molten slag composition were thermodynamically analyzed considering the interaction coefficients measured in this work. When the scrap ratio was increased, the copper and tin contents of hot metal were increased, leading to the increase in the Mn content of the hot metal. However, the Mn content of hot metal was decreased by increasing the scrap ratio because the input amount of MnO was reduced.

The Fines2EAF project aims to increase the value of Electric Arc Furnace steelmaking residues by their internal recycling and reuse in form of cement-free briquettes. The project sustainability for a profitable fines’ recirculation pass through the conservation of steel and slag quality in terms of chemistry, physics and eco friendliness. To do this, industrial trials have been conducted by the charging of self-reducing and slag-former briquettes made by primary and secondary fines materials. Several slag samples supplied from three different European EAF steel shops have been analysed. The specimens have been characterized by XRF, XRD and SEM to thoroughly define their crystallography, morphology and microstructure. The comparison with the corresponding reference samples (i.e., slag produced without the fines recirculation) also allowed to highlight the differences present. Leaching tests have been conducted on reference and briquette-added slag according to EN 12457-4 standard to assess the compliant with the local environmental regulation. The obtained results highlighted that the slag obtained using cement-free briquettes made by steelmaking fines exhibits crystallographic and morphological properties very similar to the reference samples, with limited differences attributed to slag and scrap feedstock intrinsic heterogeneity. No relevant increase in the leachate concentration could be detected when compared to reference samples and the influence of raw-material fines recirculation into the EAF could be considered at worst negligible, if not positive for some elements like Ba (−22.86%), V (−13.19%) and W (−14.83%). Considering all the analyses performed, no adverse effect on slag quality could be detected.