Search Results (45)

The accelerated industrialization in China has precipitated a dramatic surge in solid waste generation, causing severe land resource depletion and posing substantial environmental contamination risks. Simultaneously, the cement industry has become characterized by the intensive consumption of natural resources and high carbon emissions. This review aims to investigate the current technological advances in utilizing industrial solid waste for cement production, with a focus on promoting resource recycling, phase transformations during hydration, and environmental management. The feasibility of incorporating coal-based solid waste, metallurgical slags, tailings, industrial byproduct gypsum, and municipal solid waste incineration into active mixed material for cement is discussed. This waste is utilized by replacing conventional raw materials or serving as active mixed material due to their content of oxygenated salt minerals and oxide minerals. The results indicate that the formation of hydration products can be increased, the mechanical strength of cement can be improved, and a notable reduction in CO₂ emissions can be achieved through the appropriate selection and proportioning of mineral components in industrial solid waste. Further research is recommended to explore the synergistic effects of multi-waste combinations and to develop economically efficient pretreatment methods, with an emphasis on balancing the strength, durability, and environmental performance of cement. This study provides practical insights into the environmentally friendly and efficient recycling of industrial solid waste and supports the realization of carbon peak and carbon neutrality goals. Full article

The metallurgical industry has been constantly changing over the past decades. On the one hand, there has been the modernization and improvement of production efficiency, and on the other hand, we have seen a reduction in the negative impact on the environment. The possibility of using alternative materials and the circular economy is significant in this area. In the present work, research was carried out to determine the usefulness of biomass in the form of fruit seeds for the recycling processes of metal-bearing raw materials, including slags from copper production processes, which are characterized by a much higher metal content than ores of this metal. The main carbon-bearing material/reducer used in the process is metallurgical coke. The transformation of the European metal industry has been observed in recent years. To carry out the physicochemical characterization of the tested material, a research methodology was adopted using tools to determine the stability of behavior at high temperatures, chemical composition, and volatile components. Thermodynamic analysis was carried out, indicating the theoretical course of reactions of individual system components and thermal effects, allowing a determination of whether the assumed reactions are endothermic or exothermic. The planned research ends with the reduction process in conditions similar to those carried out in industrial conditions. Enforced by the guidelines for reducing CO₂ emissions, it contributes to a significant reduction in the demand for coke. This paper addresses the issue of determining the feasibility of using selected bioreducers, including cherry stones, to verify their suitability in the process of reducing copper oxides. The study used copper slag with a composition similar to slags generated at the copper production stage in a flash furnace. The results obtained in reducing copper content above 98 wt. % indicate the great potential of this type of bioreducer. It should be noted that, unlike conventional fossil fuels, the use of cherry stones to reduce copper slag can be considered an environmentally neutral method of carbon offset. The resulting secondary slag is a waste product that can be stored and disposed of without harmful environmental effects due to its low lead content. An additional advantage is the relatively wide availability of cherry stones. Full article

Amid escalating global climate crises and the urgent imperative to meet the Paris Agreement’s carbon neutrality targets, the steel industry—a leading contributor to global greenhouse gas emissions—confronts unprecedented challenges in driving sustainable industrial transformation through innovative low-carbon steelmaking technologies. This paper examines decarbonization technologies across three stages (source, process, and end-of-pipe) for two dominant steel production routes: the long process (BF-BOF) and the short process (EAF). For the BF-BOF route, carbon reduction at the source stage is achieved through high-proportion pellet charging in the blast furnace and high scrap ratio utilization; at the process stage, carbon control is optimized via bottom-blowing O₂-CO₂-CaO composite injection in the converter; and at the end-of-pipe stage, CO₂ recycling and carbon capture are employed to achieve deep decarbonization. In contrast, the EAF route establishes a low-carbon production system by relying on green and efficient electric arc furnaces and hydrogen-based shaft furnaces. At the source stage, energy consumption is reduced through the use of green electricity and advanced equipment; during the process stage, precision smelting is realized through intelligent control systems; and at the end-of-pipe stage, a closed-loop is achieved by combining cascade waste heat recovery and steel slag resource utilization. Across both process routes, hydrogen-based direct reduction and green power-driven EAF technology demonstrate significant emission reduction potential, providing key technical support for the low-carbon transformation of the steel industry. Comparative analysis of industrial applications reveals varying emission reduction efficiencies, economic viability, and implementation challenges across different technical pathways. The study concludes that deep decarbonization of the steel industry requires coordinated policy incentives, technological innovation, and industrial chain collaboration. Accelerating large-scale adoption of low-carbon metallurgical technologies through these synergistic efforts will drive the global steel sector toward sustainable development goals. This study provides a systematic evaluation of current low-carbon steelmaking technologies and outlines practical implementation strategies, contributing to the industry’s decarbonization efforts. Full article

The environmental impacts of industrial processes have increased the demand for sustainable alternatives in wastewater treatment. Conventional chemical coagulants, though widely used, can generate toxic residues and pose environmental and health risks. Biocoagulants, derived from natural and renewable sources, offer a biodegradable and eco-friendly alternative. This review explores their potential to replace synthetic coagulants by analyzing their origins, mechanisms of action, and applications. A total of 15 studies published between 2020 and 2025 were analyzed, all focused on industrial wastewater. These studies demonstrated that biocoagulants can achieve similar, or the superior, removal of turbidity (>67%), solids (>83%), and heavy metals in effluents from food, textile, metallurgical, and paper industries. While raw materials are often inexpensive, processing costs may increase production expenses. However, life cycle assessments suggest long-term advantages due to reduced sludge and environmental impact. A textile industry case study showed a 25% sludge reduction and improved biodegradability using a plant-based biocoagulant compared to aluminum sulfate. Transforming this waste into inputs for wastewater treatment not only reduces negative impacts from disposal but also promotes integrated environmental management aligned with circular economy and cleaner production principles. The review concludes that biocoagulants constitute a viable and sustainable alternative for industrial wastewater treatment. Full article

The growing environmental impact of copper production necessitates innovative approaches for optimizing metallurgical processes and minimizing waste. This study addresses this challenge by leveraging advanced machine learning (ML) techniques to enhance the efficiency of pyrometallurgical operations such as slag optimization, composition prediction, and waste minimization. Using a combination of real-world and synthetic data, we developed models capable of both forward prediction, estimating slag and matte compositions from ore characteristics, and backward prediction, inferring ore compositions from output characteristics. Five ML algorithms were evaluated, with Gradient Boosting and Support Vector Regression demonstrating superior performance in capturing complex, non-linear relationships. Forward prediction achieved near-perfect accuracy, while backward prediction highlighted the inherent complexity of inverse modeling. This backward-driven strategy proposed in this research aims to determine optimal ore compositions to achieve desired outputs, reducing waste and energy consumption. By integrating ML models with a systematic hyperparameter optimization approach, this work advances the potential for sustainable and precise metallurgical processes. While challenges remain in refining backward predictions, the findings demonstrate the transformative potential of data-driven strategies in industrial metallurgy, paving the way for environmentally sustainable and economically efficient copper production practices. Full article

The backfill binder material is the key to the cost and performance of cemented paste backfill. This study aims to understand the current situation of metal ore backfill binders, identify industry challenges, inspire research ideas, and explore development directions. Current research investigates trends and developments of backfill binders through literature review, experience summary, field research, statistical analysis, and other methods. Firstly, the main backfill binder types are summarized, including cement, metallurgical slag, thermal slag, chemical slag, and tailings binders. Secondly, the research progress regarding reactivity activation, hydration mechanism, harmful ion solidification, energy conservation, and carbon reduction is summarized. Thirdly, three industrial applications of new backfill binders are introduced and summarized. Cement is still the most common, followed by slag powder binder. The cases of steel slag binder and semi-hydrated phosphogypsum backfill have shown significant effects. Solid waste-based backfill binder materials are gradually replacing cement, which is a trend. Finally, further research is discussed, including hydration modeling and simulation, material properties under extreme environments, hardening process control, and technical standards for backfill binders. This work provides a reference and basis for promoting green and efficient paste backfill and sustainable industry development. Full article

A silver-rich lead alloy was obtained through the recycling of two metallurgical wastes: these are lead paste obtained from spent lead–acid batteries and a jarosite residue obtained from the hydrometallurgical production of zinc. Mixtures of both wastes were pyrometallurgically treated with sodium carbonate in a silicon carbide crucible at 1200 °C. The alloy and slag produced were analyzed by atomic absorption spectrometry, X-ray diffraction, and scanning electron microscopy with energy-dispersive spectra. High silver recovery was obtained in a Pb-Ag alloy for a mixture ratio of 30% Na₂CO₃–40% lead paste–30% jarosite, reaching a silver grade of 126 ppm. The slags produced for the highest jarosite content allow the compound formation of Na₂(SO₄) and Na₂Fe(SO₄)₂, which have high sulfur-fixing, avoiding SO₂ release and contributing to the minimization of atmospheric pollution. The novel pyrometallurgical route addresses not only the valorization of precious metals such as silver and lead but also the reduction in accumulated industrial waste. Full article

Due to the emission of hazardous chemicals and heat, the traditional smelting method used to extract critical minerals from ore and mine slag/tailings is considered bad for the environment. An environmentally friendly procedure that can stabilize sulfur emissions from mine waste without endangering the environment is bioleaching. In the present study, sequential oxidative (Oxi) and reductive (Red) bioleaching of acid-pretreated copper smelter slag using iron-oxidizing/reducing Acidithiobacillus ferrooxidans was applied to investigate critical minerals’ recovery for the dissolution of copper smelter slag. In this batch flask experiment, up to 55% Cu was recovered on day 11 during the Oxi stage, which increased to 80% during the Red stage on day 20. A sequential oxidative and reductive bioleaching of an acid-pretreated copper smelter slag at pH (1.8) and 30 °C positively affects the extraction of Cu (80%), Zn (77.1%), and Al (65.3%). In contrast to the aerobic bioleaching experiment, the reduction of Fe³⁺ iron under anaerobic conditions resulted in a more significant release of Fe²⁺ and sulfate, limiting the development of jarosite, surface passivation, and the subsequent loss of metal recovery due to co-precipitation with Fe³⁺. Overall, the Oxi-Red bioleaching process combined with acid pretreatment showed promising results toward creating a method for recovering valuable metals from metallurgical waste that is economical and environmentally beneficial. Full article

Copper production technology is a complex process consisting of many stages. The combination of pyrometallurgical and hydrometallurgical stages, on the one hand, complicates production while, on the other hand, allowing for a relatively selective separation of intermediate or waste materials that can be subjected to the process of recovery of useful components. Materials of this type are characterised by a much higher copper content relative to the ore material. On the other hand, due to the oxide form, reduction processes are used in which coke is mainly applied. Reduction of the unfavourable phenomenon of CO₂ emissions, in this case, can be performed through the use of bioreducers, which are characterised by an inert carbon footprint since the generation of carbon dioxides is the same as its absorption at the stage of vegetation and growth. In this paper, the topic of determining the feasibility of using selected bioreducers, such as peanut shells, to verify their suitability in the process of reducing copper oxides as well as the impact on the working components of the laboratory reactor in which the process is carried out are discussed. In this case, raw materials with a composition similar to the that of slags produced at the copper production stage in a flash furnace were tested for reduction. The results referring to reducing lead and copper contents above 88% Pb and 98% Cu indicate the great potential of this type of bioreducer. An additional advantage is the relatively wide availability of peanut resources. The effects of the copper reduction time on the degree of decopperisation performed with a constant reducer addition at 1300 °C were studied in this paper. Following 1 h of the process, the copper content in the slag was 0.78 wt%, while the longer process duration resulted in a copper fraction of 0.19 wt%. Considering lead, its content was 0.33 wt% after the reduction process. Full article

The paper presents an analysis of the effective use of a mixture of steel sludge (S1) and slag (S2) from the converter process of steel production for the production of cement mortars. Metallurgical waste used in the research, which is currently deposited in waste landfills and heaps near plants, posing a threat to groundwater (possibility of leaching metal ions present in the waste), was used as a substitute for natural sand in the range of 0–20% by weight of cement (each). The obtained test results and their numerical analysis made it possible to determine the conditions for replacing part of the sand in cement mortars with a mixture of sludge and slag from a basic oxygen furnace (BOF) and to determine the effects of such modification. For the numerical analysis, a full quadratic Response Surface Model (RSM) was utilized for two controlled factors. This model was subsequently optimized through backward stepwise regression, ensuring the inclusion of only statistically significant components and verifying the consistency of residual distribution with the normal distribution (tested via Ryan-Joiner’s test, p > 0.1). The designated material models are helpful in designing ecological cement mortars using difficult-to-recycle waste (i.e., sludge and converter slag), which is important for a circular economy. Mortars modified with a mixture of metallurgical waste (up to 20% each) are characterized by a slightly lower consistency, compressive and flexural strength, and water absorption. However, they show a lower decrease in mechanical strength after the freezing–thawing process (frost resistance) compared to control mortars. Mortars modified with metallurgical waste do not have a negative impact on the environment in terms of leaching heavy metal ions. The use of a mixture of sludge and steel slag in the amount of 40% (slag/sludge in a 20/20 ratio) allows you to save 200 kg of sand when producing 1 m³ of cement mortar (cost reduction by approx. EUR 5.1/Mg) and will also reduce the costs of the environmental fee for depositing waste. Full article

The recovery of iron contained in mill scale rather than iron ore can be considered a promising valorization pathway for this waste, especially if carried out through reduction using biogenic carbon sources. Nevertheless, the physicochemical properties of the latter may hinder the industrial transferability of such a pathway. In this work, the mechanical and metallurgical behavior of self-reduced briquettes composed of mill scale and four biogenic carbons (with increasing ratios of fixed carbon to volatile matter and ash) was studied. Each sample achieved mechanical performance above the benchmarks established for their application in metallurgical furnaces, although the presence of alkali compounds in the ash negatively affected the water resistance of the briquettes. In terms of metallurgical performance, although agglomeration successfully exploited the reduction by volatiles from 750 °C, full iron recovery and slag separation required an amount of fixed carbon higher than 6.93% and a heat treatment temperature of 1400 °C. Finally, the presence of Ca-, Al-, and Si- compounds in the ash was essential for the creation of a slag compatible with steelmaking processes and capable of retaining both phosphorus and sulfur, hence protecting the recovered iron. Full article

A circular economy (CE) appears to be a crucial tool enabling the sustainable use of natural resources, which is also essential for achieving the Sustainable Development Agenda by 2030. Compared to the traditional linear economy policy based on the “take-make-use-dispose” principle, the CE approach guided by the “designed to be remade” principle offers immense opportunities. Not only does it drastically reduce the need for primary resources, but it also revolutionizes the management of both resources and waste. The CE is significant for metal processing companies due to increased control over resources and waste reduction. Furthermore, it enables the efficient utilization of natural resources and minimizes the negative environmental impact, translating into the sustainable development of metallurgical activities. Additionally, recycling processes in metal processing can also have financial benefits by reducing the raw material procurement costs and lowering the waste disposal fees. The CE business model of the innovation and improvement of metal processing involves optimizing resource usage through continuous material processing and reuse. Companies develop advanced recycling technologies, implement efficient resource management strategies, and adopt service-oriented business models like leasing or part exchanging. These initiatives aim to increase value addition and minimize waste. Additionally, the ongoing investment in research and development facilitates the introduction of innovative processes and materials, leading to operational enhancement and environmental sustainability. The main aim of this study was to develop a CE business model for a metal processing company. This model allowed for identifying the key elements influencing the operations of companies in this industry in terms of the CE. Research was conducted through triangulation using various methods, such as focus group interviews, surveys, and individual in-depth interviews. This study was supplemented with an investment decision-making algorithm according to the CE and the CE business model canvas for metalworking enterprises, with a focus on those producing metal products subsequently covered with galvanic coating. The presented results also propose application in other SMEs within this industry sector. Full article

Inconel 625 is a nickel-based superalloy widely used in industries such as energy, space, and defence, due to its strength and corrosion resistance. It is traditionally time- and resource-intensive to machine, leading to increased environmental impact and material waste. Using additive manufacturing (AM) technology enables a reduction in resource consumption during the manufacture of high value components, as material is only deposited where it is required. This study compares the environmental impact of manufacturing an Inconel 625 impeller through machining and wire arc additive manufacturing (WAAM) by employing established life cycle assessment methods. WAAM shows significant advantages, cutting energy consumption threefold and reducing material waste from 85% to 35%. The current work also evaluates the mechanical properties of WAAM-produced components through tensile and axial fatigue testing, in addition to the use of optical and electron microscopy for metallurgical analysis and fractography. This demonstrates yield and ultimate tensile strengths exceeding industrial standards, with comparable or superior fatigue life to other AM methods. The improved fatigue performance extends the service life of components, bolstering sustainability by reducing the need for frequent replacements, thereby lessening associated environmental impacts. These findings underscore the promise of WAAM in enhancing both environmental sustainability and mechanical performance in manufacturing Inconel 625 components. Full article

The metallurgical sector is one of the important sectors of the Slovak economy. Its integral part is the storage of metallurgical waste, which is accompanied by noise that bothers the inhabitants of the surrounding urban areas. This paper focuses on the analysis of the problem of noise propagation into protected areas located in the vicinity of the metallurgical plant. The paper describes a number of measurements that have been carried out at the slag landfill. Based on these measurements, simulations were performed using a mathematical model, and predictions of noise propagation in the exterior were made. Subsequently, noise reduction measures were proposed. The results obtained by the authors form a methodological basis for addressing such situations, since, during the solution, it was often necessary to deal with non-standard situations that were specific to the area of the technology addressed. This solution was then applied in real practice. Full article

Applying industrial by-products as a substitution for conventional construction materials (natural resources) is a superior solution for the environment in terms of waste management and reduction in greenhouse emissions and for the construction industry in terms of cost and expenditure. Applying basic oxygen furnace slag (BOFS), one of the metallurgical industry by-products, as a construction material can be a high-potential and promising idea. However, the utilization of BOFS in construction applications is considerably limited because of its inherent characteristics leading to volumetric expansion behavior caused by the chemical reaction between free lime (f-CaO) and water. This study used geopolymer technology to stabilize the expansive behavior of chronologically aged BOFS aggregates. The compressive strength, expansion behavior, and drying shrinkage characteristics of a normal ordinary Portland cement (OPC) mixture and a geopolymer mixture containing siliceous river sand and chronologically aged BOFS aggregates were investigated. The test results showed that the compressive strength of geopolymer mixtures containing chronologically aged BOFS aggregate achieved 64.02 MPa, and the expansion behavior of geopolymer mixtures was improved compared with normal OPC mixtures containing the same BOFS aggregates, reaching 0.02% and 0.44%, respectively. However, due to the air-curing method, geopolymer mixtures had higher drying shrinkage values than normal OPC mixtures. Therefore, further studies should be conducted to investigate how to control the drying shrinkage of geopolymer mixtures containing chronologically aged BOFS aggregate. Full article