The iron and steel sector is a key driver of global economic development and is one of the largest consumers of industrial energy, largely dependent on fossil fuels. Within this sector, sinter making is a vital step in the ironmaking process, accounting for approximately 10% of total energy use—of which about 78% is derived from coke breeze. This heavy reliance contributes substantially to greenhouse gas emissions, as well as SOx and NOx pollutants. Replacing fossil fuels with biomass, a renewable and cleaner energy source, presents a promising path toward carbon-neutral sintering. This study explores the potential of biochar, obtained through the pyrolysis of biomass, as a viable and sustainable fuel alternative in the sintering process. The present study investigates the feasibility of replacing solid fuel upto 100 % within the sintering process with biochar through lab scale sinter pot trials. Biochar's high carbon content, improved energy density, and low volatile matter make it a promising candidate for enhancing thermal efficiency and reducing greenhouse gas emissions. Charcoal with a size fraction of -3.15 mm was used for the current trials. In comparison to the conventional mix, sinter blends incorporating charcoal demanded higher moisture content to attain effective granulation, primarily due to charcoal's higher porosity and moisture absorption capacity. The use of charcoal as a partial fuel substitute in the sintering process led to a noticeable reduction in the green mix bulk density due to its inherently lower material density. This change also contributed to a decline in the balling index, indicating weaker pellet formation. Additionally, increased charcoal content disrupted the consistency of the heat and flame fronts, resulting in reduced thermal efficiency and a subsequent decrease in sinter yield. However, the higher combustibility and volatile matter of charcoal enabled faster temperature build-up, which shortened the overall sintering time. Despite these changes, sinter productivity remained within an acceptable operational range. The presence of charcoal affected the exhaust gas composition, with a reduction in overall SO₂ and NO_x emissions. With increasing biochar substitution, NOx emissions were reduced from approximately 100 ppm to 34 ppm, while SO₂ emissions decreased from around 5.3 ppm to 3.3 ppm. 

The use of biocoke in metallurgical processes to reduce the carbon footprint of metal production has gained significant traction in recent years. This trend is particularly evident in Central Europe, where biocoke production has grown rapidly. While utilization of biocoke has already become standard in certain processes, such as ferroalloy production, its implementation in other metallurgical routes remains challenging [1].

Key limitations include its high surface area and reactivity, low mechanical strength, and low bulk density. These properties often make even partial substitution of fossil carbon infeasible - especially in systems like rotary kilns, small shaft furnaces or vertical retorts. In such setups, the reducing agent undergoes a pre-heating phase and ideally remains inert for one to two hours before entering the reduction zone. Under these conditions, conventional biocoke is ineffective [1, 2].

At the Chair of Nonferrous Metallurgy, Technical University of Leoben, new strategies have been developed to tailor the properties of pyrolyzed biomass for metallurgical use. Through advanced micro-granulation combined with small quantities of special additives, reactivity can be reduced by at least 50%. This treatment also enhances density and improves performance in possible subsequent agglomeration processes such as briquetting.

This presentation highlights the described optimization steps, which are currently the subject of a patent application. It also presents results from the investigation in various additives and discusses initial implementation trials in advanced lab-scale vertical retorts, shaft furnaces, and rotary kilns focusing on different metal recycling processes in the field of zinc, copper and lead containing resources. Finally, the entire production chain for optimized biocoke is evaluated using different woody biomass feedstocks.

steel production is one of the main pillars of modern society and, although different technological routes can be used, much of the world's production depends on metallurgical coke as a strategic input for the blast furnace process. Its manufacture, however, is based on the use of coal, a non-renewable resource that is in the process of depletion. In this context, control measures and strategies for the rational use of coal are indispensable, both for the sustainability of the process and for reducing environmental impacts. The objective of this article is to conduct a bibliographic survey of publications related to machine learning techniques applied to the prediction of coke quality indices: CRI (Coke Reactivity Index), CSR (Coke Strength after Reaction), DI (Drum Index), ash, sulfur, and moisture content. The study identified a gap in research specifically focused on moisture, ash, and sulfur content indices, despite their relevance to coke quality, pointing to the need to expand studies on these parameters, which are fundamental not only to process performance but also to energy efficiency, reducing greenhouse gas (GHG) emissions, and the sustainability of steel production. In addition, this work suggests the development of coke quality prediction models based on machine learning techniques, supported by interpretability tools such as SHAP (SHapley Additive exPlanations). Complementarily, it points to the exploration of mathematical optimizations aimed at reducing the cost of the coal mix, which can be integrated with the use of genetic algorithms. These, in turn, stand out for their ability to deal with nonlinear constraints and multiple objectives, offering robust solutions for the formulation of more economical mixtures with better operational performance.

Carbon produced via methane pyrolysis in metallic melts represents a promising sustainable alternative to conventional graphite. This material combines a CO₂-reduced production pathway with physical and chemical properties that can be tailored for high-performance applications. Due to the presence of metallic residues (e.g., Cu, Fe, Sn) introduced during the pyrolysis process, a comprehensive analytical approach is required to evaluate its structural integrity, purity, and functionality [1].

This study presents a multimodal characterization strategy combining Raman spectroscopy, scanning electron microscopy (SEM), and X-ray fluorescence analysis (XRF). Raman spectroscopy provides detailed insights into carbon bonding states, crystallinity, and defect density, particularly through the evaluation of D-, G-, and 2D-bands. SEM imaging enables morphological analysis, surface topology assessment, and particle size evaluation at sub-micrometer resolution. XRF complements these methods by quantifying trace metallic impurities originating from the melt environment, which may influence subsequent material processing and application behavior [2,3].

The obtained results serve as a basis for targeted purification and refinement processes that enable the use of pyrolysis-derived carbon as a functional material across a wide range of applications. Potential use cases include bipolar plates for fuel cells, anode materials for lithium-ion batteries, electrically conductive polymers, expandable flame-retardant fillers, lubricants, and electrodes for electric arc furnaces. The unique combination of graphite-like properties with a sustainable synthesis route addresses the increasing industrial demand for environmentally friendly high-performance materials. A central challenge remains the precise adjustment of material characteristics to meet specific performance requirements in each application sector [4–6].