Metallurgical Research Articles

Arsenic accumulation in spolic technosols in the area of a large copper smelting plant in the Middle Urals

Relevance. The necessity to study arsenic behaviour in soils as one of the main pollutants of depositing environments in areas of mining and metallurgical industry. In recent decades, arsenic emissions into the environment have reached a huge scale, so this element attracts the attention of researchers around the world. But in spite of all the studies of this problem, there are still some aspects that need to be clarified to understand the geochemistry of arsenic. This paper deals with spolic technosols with critically high arsenic content in the soil profile with alternating water-logged and dry conditions. As one of the main soil-forming elements, orthosteins contain significant amounts of iron and manganese compounds and are capable of adsorption and involvement of the elements in nodule formation. Aim. To determine the influence of orthosteins on arsenic accumulation in soil subjected to intensive anthropogenic load. Object. Ortsteins spolic technosols in the zone of operation of copper smelting plant and background soils not exposed to pollution. Methods. Arsenic was determined by inversion voltammetry method. Morphological characterisation and patterning of the orthosteins were performed by scanning electron microscopy using a Thermo Fisher Phenom XL G2 Desktop SEM unit. Results. The study of morphological features of orthosteins revealed differences in soils subjected to greater anthropogenic load. Arsenic was not detected inside the orthosteins in all studied soils. Also arsenic concentrations in the total mass of ortstein is up to 40–50% of the soil mass. This fact indicates the accumulation of arsenic by surface adsorption and the appearance of orthosteins as a geochemical barrier. The data obtained in the course of this work can contribute to the search for ways to clean up soils contaminated with arsenic, as well as provide an understanding of the basic processes of the behaviour of this element in soil formation.

Recycling of iron-rich basic oxygen furnace dust using hydrogen-based direct reduction

The reduction of iron oxide-bearing ores necessitates the exploration of alternatives. Recycling iron oxide-enriched metallurgical dust could serve as secondary raw material for metallurgical processes. Implementing environmentally friendly technologies utilizing hydrogen has prompted the concept of hydrogen reduction of metallurgical dust to recycle secondary steel production products. The present study investigates the characteristics of hydrogen reduction of briquettes and pellets produced from basic oxygen furnace dust and reduced at the temperature of 850 °C. Experimental results revealed that the reduction degree for pellets was approximately 1.5 times higher compared to briquettes. The reduction swelling index of pellets was noticeable lower compared to literature data of reduction swelling index for iron ore pellets. Scanning electron microscopy/energy-dispersive X-ray spectroscopy was carried out to detect changes in the microstructure and chemical composition of the samples. Subsequent melting of the reduced samples unveiled non-metallic inclusions within the iron alloy and the impact of slag on their distribution between the alloy and slag.

Anisotropic creep property related to non-spherical shape of mechanically alloyed powder of oxide dispersion strengthened F82H

Nanometric oxide particles dispersed within the matrix play an important role in improving the creep property of Oxide Dispersion Strengthened (ODS) steels. Conventional studies have primarily focused on investigating the distribution of the particles to control the creep property of ODS steels. However, achieving complete control over the creep property still poses challenges, as there are potentially other microstructural features like different matrices, micrometric precipitates, and inclusions derived from powder metallurgical processes that can influence it.In our previous research, we examined one such microstructural feature known as prior particle boundary (PPB). PPB refers to the surface of mechanically alloyed (MA) powder before consolidation. We revealed that the ODS steel with fine PPBs produced from smaller MA powder, exhibited shorter creep rupture times, compared to that with coarse PPBs produced from larger MA powder. This result was attributed to the increased formation of creep cavities on the PPBs in the ODS steel produced from smaller MA powder. Therefore, the size of MA powder affected the formation of creep cavity and had an impact on the creep property.In this study, we shifted our focus to the shape of MA powder with non-spherical shapes containing flake-like shape. Such shapes have the potential to induce anisotropy in the formation of creep cavities and/or the creep crack initiation and growth along anisotropic prior particle boundaries (PPBs), ultimately leading to anisotropic creep behavior.We conducted small punch creep tests on specimens with two different orientations to study the possible anisotropy. The results revealed that the creep rupture times varied depending on the orientation of specimen, thus indicating anisotropic creep property. This anisotropic creep property was related to the non-spherical shape of MA powder. This research highlighted the significance of managing the shape of MA powder in controlling the creep property of ODS steels.

Potential and characteristics of rare-earth metals acid bioleaching from the rare-earth-rich tailings with the enriched functional bacterial consortium: Comparison between one-step and two-step processes

The irreplaceable roles of rare-earth metals (REMs) in modern technologies have renewed interest in the grand challenges of mineral processing and metallurgical engineering—the efficient extraction of REMs. However, traditional methods for extracting REMs are inefficient, costly and harmful to health and the environment. In this study, a method of biological extraction (bioleaching), which has been proved to be effective in the field of mineral processing for extraction of the metals, was employed for REMs bioleaching from Bayan Obo rare-earth-rich tailings (RERT) using the acid functional bacterial consortium, and the optimal culture and leaching conditions were optimized. Under the optimal conditions for 18 days, the total bioleaching rate of the five main REMs of La, Ce, Pr, Nd and Sm was obtained at 82.78 % for one-step process and 83.51 % for two-step process, which has a significant improvement comparing to previous studies. The results demonstrated that REMs could be efficiently bioleached by acid bioleaching functional bacterial consortium, and the difference in leaching efficiency between the one-step and two-step bioleaching process was not significant. In addition, by analyzing the mineral composition of the RERT and leaching residue, the extensively bioleach of REMs in bastnaesite are observed. To sum up, the rare-earth resources of Bayan Obo RERT could be effectively leached by acid bioleaching method.

Review of Sulfate Removal in Low Concentration Brine Solutions

Sulfate is a common ion present in natural water bodies at low concentrations and as effluent in different metallurgical processes. The discharge of sulfate in rivers and waterbodies can cause direct and indirect damage to the environment. Regulatory agencies have been increasing the constraints in sulfate content limit for discharge focused on human equity and environmental protection. A common practice is the precipitation of sulfate with lime, but the remaining solution still has ca. 1,500 mg L-1 of sulfate, which is not acceptable for disposal or reuse. This work describes the main routes for sulfate removal such as chemical precipitation, biological degradation, ion exchange, and separation through membranes and discusses the main advantages and issues of each approach. One of the main challenges is to scale up the tests and show the performances at the industrial level. The subject must be the focus of constant study to obtain relevant results so that usual technologies are replaced by more innovative, cheap and efficient methods.

Wpływ emisji przemysłu metalurgicznego na rozwój wybranych składników depozycji atmosferycznej na terenie Koszyc (Słowacja)

The aim of this paper is to assess the impact of emissions and their decrease on the level of environmental burden through the study of selected atmospheric deposition parameters in the area with the dominant source of emissions from the iron and steel production complex. Total atmospheric deposition (AD), i.e., j. both wet and dry, was sampled from eleven sampling points at a distance of 3 to 16 kilometers from the ironworks complex. AD fluxes of selected elements (Fe, Al, Mn, Zn, Pb, Cu, Cr, Cd, As) and dust particles (PM) were evaluated in relation to the amount of emissions from the results of long-term AD monitoring (2009 – 2022). The analysis shows the dominant influence of emissions from the metallurgical industry on the deposition fluxes of most of the monitored parameters and, thus, on the environmental burden of the area. The emissions have a decisive impact on the AD of manganese, iron, chromium, particulate matter, zinc, and aluminum, but also, to a lesser extent, on the AD of the other monitored elements. Correlation analysis confirmed a statistically significant dependence between the amount of emissions and the mass fluxes of AD for iron, zinc, manganese, and chromium for most of the sampling sites. The potential of immission load of the urban environment of Košice by emissions from the metallurgical industry is significantly higher in the winter due to local specific meteorological conditions. The more than sevenfold decrease in emissions significantly affected the AD of most of the monitored parameters, but their decrease was not so significant except for the AD of lead. The average AD of the elements strongly associated with ironworks emission sources, namely iron, manganese, chromium, and zinc, decreased approximately twofold. The amount of emissions is only one of several factors that affect the quantity of fluxes of the monitored AD parameters. In addition to seasonal factors, local meteorological, climatic, orographic, and other local conditions, and specifics also play an essential role.

Evaluation of functional characteristics of Acidithiobacillus thiooxidans microencapsulated in gum arabic by spray-drying as biotechnological tool in the mining industry.

The mining and metallurgical industry represents one of the leading causes of environmental pollution. In this context, the optimization of mineral waste management and the efficient extraction of metals of interest becomes an imperative priority for a sustainable future. Microorganisms such as Acidithiobacillus thiooxidans have represented a sustainable and economical alternative in recent years due to their capacity for environmental remediation in bioleaching processes because of their sulfur-oxidizing capacity and sulfuric acid generation. However, its use has been limited due to the reluctance of mine operators because of the constant reproduction of the bacterial culture in suitable media and the care that this entails. In this work, the central objective was to evaluate the functional characteristics of A. thiooxidans, microencapsulated and stored at room temperature for three years in vacuum bags, using a spray drying process with gum arabic as a wall vector. Growth kinetics showed a survival of 80 ± 0.52% after this long period of storage. Also, a qualitative fluorescence technique with a 5-cyano-2-3 ditolyl tetrazolium (CTC) marker was used to determine the respiratory activity of the microorganisms as soon as it was resuspended. On the other hand, the consumption of resuspended sulfur was evaluated to corroborate the correct metabolic functioning of the bacteria, with results of up to 50% sulfur reduction in 16 days and sulfate generation of 513.85 ± 0.4387 ppm and 524.15 ± 0.567 ppm for microencapsulated and non-microencapsulated cultures, respectively. These results demonstrate the success after three years of the microencapsulation process and give guidelines for its possible application in the mining-metallurgical industry.

Numerical Simulation as a Tool for the Study, Development, and Optimization of Rolling Processes: A Review

Rolling is one of the most important processes in the metallurgical industry due to its versatility. Despite its inherent advantages, design and manufacturing by rolling still rely on trial-and-error-based optimizations, which reduces its efficiency. To minimize the cost and time spent on the development of new rolling schedules, various analytical and numerical methods have been used in recent years. Among other alternatives, simulations based on the finite element method (FEM) are the most widely used. This allows for the analysis of the feasibility of new rolling schedules considering metal alloys with different characteristics, process conditions, or the creation of new operations, as well as the optimization of existing ones. This paper presents a literature review including the latest developments in the field of numerical simulation of rolling processes, which have been classified according to the type of rolling into the following categories: flat rolling, shape rolling, ring rolling, cross-wedge rolling, skew rolling, and tube piercing.

Microstructural and Tensile Property Differences between Ni-16Mo and ODS alloys Fabricated by the Powder Metallurgy Processes

Ni-16Mo and ODS alloys were fabricated by the powder metallurgical processes, and their microstructures and tensile properties were investigated. Ni-16Mo-7Cr and Ni-16Mo-7Cr-0.3Ti-0.35Y2O3 (in wt.%) alloys were prepared by mechanical alloying, uniaxial hot pressing, and heat treatment processes. Microstructural observations of these alloys revealed that the Ti and Y2O3 additions to a Ni-16Mo alloy were significantly effective to refine the grain size and form nano-sized Y-Ti-O oxide particles. Consequently, the tensile strengths at room temperature and 700°C were considerably enhanced. This improvement of tensile properties can be mainly attributed to the formation of nano-sized oxide particles, as well as the refined grain size. It is thus concluded that Ni-16Mo alloy with Ti and Y2O3 additions would be very effective in improving the mechanical properties especially at elevated temperatures.

Iron ore development management in the Russian Federation

The Russian mineral resource complex is the basis for economy real sector development. The reserves of oil, gas, ferrous and non-ferrous metals, timber, and other raw materials are the strategic basis for the state economic development stability. The subject of the study is iron ore, by reserves of which Russia is confidently among the top three countries in the world together with Australia and Brazil. The global statistics on iron ore production looks a little different since China and India are ahead of Russia in terms of production volumes after the above-mentioned countries. At a time when the country is facing the task of achieving technological sovereignty, and the metallurgical industry is the driver of developing such industries as machine building, construction, and energy, the mineral and raw materials complex development issues are of undeniable interest and relevance. The technological development strategy of Russia will rely in its implementation on a stable metallurgical industry, where issues and main directions of ferrous metallurgy development have been identified, which are the main purpose of this study.

Analysis of Oxygen Consumption in Lead and Zinc Metallurgy

This article analyzes the role of oxygen in lead zinc metallurgy, including shortening the metallurgical process, promoting energy conservation and environmental protection, improving metallurgical strength, enhancing raw material adaptability, and enhancing comprehensive recovery efficiency. This article introduces different lead zinc metallurgical processes and their oxygen consumption characteristics, including oxygen enriched side blowing lead smelting, oxygen bottom blowing lead smelting, oxygen enriched top blowing lead smelting, flash smelting lead, oxygen pressure leaching zinc smelting, and atmospheric pressure oxygen leaching zinc smelting. It is pointed out that oxygen enhanced metallurgy is the direction for the transformation and upgrading of lead zinc metallurgy.

Psychological research in vibration disease: level of alexithymia, psychological defenses

Vibration disease ranks among the first in the structure of diseases in workers at mechanical engineering enterprises, metallurgical, mining, and construction industries, various branches of agriculture, and aircraft manufacturing. A change in the mental status of people working in vibration conditions was identified; the most common are «neurosislike states» with psycho-emotional disorders of anxiety type. Meanwhile, currently existing data on the state of the nervous system in vibration pathology are contradictory and scarce, which requires a more in-depth study. Purpose of the study: to investigate the psychological status of patients with vibration disease from the action of both local and general vibration. Research results. In patients with vibration disease from the action of both local and general vibration, a predominance of destructive psychological defenses (projection and repression) over constructive ones (compensation and rationalization) is observed.

Self Organizing Maps (SOM) and statistical methods for describing the physicological profile of undergraduates students of engineering

To meet a Brazilian guideline for engineering courses, which advocates the use of active learning in applied disciplines, this research studies new students entering in the Metallurgical Engineering Course in Escola Politécnica of Universidade de São Paulo (PMT/USP). It was applied to them a traditional MTBI (Myers–Briggs Type Indicator) questionary with the aim of finding out if there is recurrence of psychological profiles and to understand the characteristics of the freshmen to learning. This information was subjected to statistical analysis to observe the recurrence of the psychological characteristics of freshmen over the years (2017 to 2021). The data was also subjected to the Self Organizing Maps (SOM) machine learning technique, to delineate and group the psychological profiles observed in the students, enabling the analysis of the psychological characteristics and the comparison with the results obtained via statistics. After that, the results from the MBTI Traditional and the SOM clustering were submitted to comparison methods through multivariate statistics and Multiple Correspondence Analysis (MCA). It was found that there is recurrence of psychological characteristics between the years of collection, what were the psychological profiles of these freshmen as to how they learned. It was found that the freshmen surveyed mostly belong to Generation Z (or iGen) and characteristics pertinent to this group were observed. A scenario is obtained to point out the best active learning techniques for these students with the verification of recurrence of profiles and other correlated psychological characteristics, aiming to provide the most effective teaching in the engineering course.

Energy saving model for related processes in steelmaking

In the development of advanced energy saving technologies in the metallurgical industry, a comprehensive approach to managing energy flows is crucial. This article presents an in-depth analysis of the steelmaking and metallurgical industry in China and Russia, focusing on the evolution and current shortcomings of energy saving methods in metallurgical processes. The authors thoroughly analyze various technological processes, including sintering, coking, pellet production, iron production in blast furnaces, steel production in oxygen converters and electric arc furnaces, as well as steel rolling, identifying significant potential for enhancing energy efficiency and reducing harmful emissions. The main outcome of the research is the development of structural models of technological processes based on the concept of energy saving “temperature matching, cascade utilization, and global linkage”, covering key stages of steelmaking. These models provide detailed descriptions of the role and interrelation of each process within the complete metallurgical cycle and combine into a comprehensive structural model of steelmaking technological process. The model includes not only specific operations and characteristics of each stage but also explains how these processes interact and depend on each other, forming an integrated and interconnected system of metallurgical production. This model encompasses comprehensive temperature-pressure and production links, providing a theoretical basis for the development of mathematical models of energy saving and the design of corresponding computer applications. The structural model of steelmaking technological process is important for understanding and optimizing the entire process of metallurgical production, contributing to its energy and ecological efficiency.

Modern Use of Biochar in Various Technologies and Industries. A Review

The article analyzes the use of biochar in various industries and the national economy (as a sorbent, fuel, reducing agent in the metallurgical industry, a component of coal coke blends, biocomposites, modification of explosives, fertilizers, etc.) It is noted that the direction of use depends on the quality and characteristics of biochar (size, physical properties, chemical composition), which are determined by the nature of the raw material, its chemical composition and carbonization temperature.

Entropy optimized radiative flow conveying hybrid nanomaterials [formula omitted] with melting heat characteristics and Cattaneo-Christov theory: OHAM analysis

Here flow for radiative hybrid-nanomaterial (MgO+MoS2) satisfying Darcy-Forchheimer relation is addressed. Ethylene glycol C2H6O2 is utilized as a base fluid. Magnesium oxide (MgO) and Molybdenum disulfide (MoS2) are considered as distinct nanoparticles. Thermal expression is examined through heat generation and viscous dissipation. Analysis for Cattaneo-Christov theory is carried out. Condition for melting heat is deliberated. Entropy generation is examined. Variable thermal conductivity of hybrid nanomaterial is taken. Suitable transformations are implemented to obtain nonlinear dimensionless systems. Optimal homotopy analysis method (OHAM) is implemented for computations. Temperature, velocity and entropy generation are scrutinized physically. Nusselt number and skin friction are discussed. Conclusion synthesis salient points. Present work is relevant in metallurgical engineering and polymer processing. The findings conclude that Forchheimer number correspond to decline in velocity. Entropy rate and thermal field have similar trend for heat generation variable. A decrease in velocity against melting variable is noted. Temperature increases for variable thermal conductivity and thermal relaxation parameters. Entropy optimization improved for Brinkman number. Skin friction decays for porosity parameter and Forchheimer number. Skin friction improves for melting variable and Forchheimer number. Entropy augments against higher thermal relaxation time. Higher melting variable lead to an enhancement for Nusselt number. There is an improvement for radiation through Nusselt number and temperature.

Thermodynamic re-optimization of the CaO–SiO2 system integrated with experimental phase equilibria studies

CaO–SiO2 is the key system in ferrous and non-ferrous metallurgy, ceramic manufacture, cement production, and other applications. A number of discrepancies and gaps in knowledge has been identified and resolved since the last thermodynamic optimization of this system. This study reports new experimental phase equilibria data measured using recent advances in equilibration, sample quenching, and Electron Probe X-ray Microanalysis (EPMA) technique. An updated self-consistent set of thermodynamic model parameters is provided. Most importantly, these updates are integrated with a complete re-assessment of the 20-component Cu–Pb–Zn–Fe–Ca–Si–O–S–Al–Mg–Cr–Na–As–Sn–Sb–Bi–Ag–Au–Ni–Co system directly relevant to applications in the ferrous and non-ferrous metallurgical industries. To obtain a large single set of model parameters, significant advances were made in the computational approach, with a focus on simultaneous parallel optimization of binary and ternary model parameters using an experimental dataset combining binary, ternary, and multicomponent information. The Modified Quasichemical Formalism is used for the liquid slag phase. Thermodynamic properties of solid phases and liquid endmembers are completely revised following the recommendations for the third generation of CALPHAD databases. Other notable changes include the revision of the melting temperature of CaO, justified by extrapolations from the multicomponent systems, as well as a physically realistic heat capacity function for metastable SiO2 below the glass transition temperature. These updated properties expand the areas of application of the database to amorphous and partially crystallized slags at ambient temperatures, such as thermodynamics and kinetics of leaching of toxic elements in an aqueous environment. The fundamental limitations of the existing Modified Quasichemical Formalism are also discussed, along with strategies for addressing them.

Alkaline flux dissociation in blast furnace tuyere bird’s nest: Part 1: CaO dissolution kinetics and slag physicochemical evolution in the coal-coke-slag

In the pursuit of optimizing smelting efficiency and minimizing carbon emissions in blast furnace operations, the strategic introduction of the tuyere alkaline flux injection, particularly in managing the viscosity of the coal-coke-slag in the bird’s nest region, is investigated. This study focused on exploring the dynamics of CaO dissolution within the slag of the coal-coke-slag in the bird’s nest area of a 2200 m3 blast furnace in China, particularly under conditions of instability. Quantitative analysis revealed that at 1550 °C, the CaO maximal dissolution capacity reached 62.05 wt%, with an average rate constant of dissolution observed at 4.65 × 10−4 s−1. The dissolution mechanism was characterized by interfacial dissociation, mass transfer diffusion, and the attainment of a dynamic equilibrium, predominantly influenced by the Ca2+ concentration gradient within the slag. This process facilitates the depolymerization of the slag’s network structure, heavily influenced by the aluminum oxide tetrahedron, effectively reducing slag viscosity. Further, the study quantified the optimal CaO injection content through the tuyere, suggesting a range of 4.00–5.32 kg/tHM, contingent on the use of high-quality raw fuel and advanced high wind temperature technology. This work contributes valuable theoretical insights towards enhancing the efficiency and sustainability of smelting operations, applicable to both conventional and high pellet blast furnaces, marking a significant step forward in the development of low-carbon metallurgical processes.

Processes occurring during the synthesis of wollastonite‑containing refractory used in non‑ferrous metallurgy

This article presents the results of research on the processes occurring during the synthesis of wollastonite‑containing ceramics obtained from various clay components. The peculiarities of crystalline phase formation in the material are described. The obtained information lays the foundation for the organization of ceramic production that is in demand in the metallurgical industry.

A clean and green technology for iron extraction from refractory siderite ore via fluidization self-magnetization roasting

As a refractory iron resource, siderite has gained significant attention in the fields of mineral processing and metallurgical industry due to its abundant availability. However, its direct utilization in iron and steel production is often hindered by the presence of impurities, including silicates and carbonates, as well as the lower theoretical iron grade so it is necessary to increase iron and reduce impurities. To unlock the full potential of these abundant iron ore deposits, advanced processing techniques are imperative. In this work, a clean and green technology was proposed for extracting iron from siderite via fluidization self-magnetization roasting and magnetic separation. The mechanism of fluidization self-magnetization was investigated by thermodynamic analysis, X-ray diffraction (XRD), iron phase analysis, Mineral Liberation Analyzer (MLA), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS). The results show that concentrate with a Fe grade of 61.74% and Fe recovery of 81.78% could be obtained after treatment by fluidization self-magnetization roasting and magnetic separation. The analysis reveals the siderite eventually transformed into magnetite after fluidization self-magnetization roasting, with the saturation magnetization increasing from 0.91 A·m2·kg−1 to 7.92 A·m2·kg−1. In this process, many cracks were generated on the surface of the ore, which not only likely contributes to the self-magnetization roasting but also facilitates the individual dissociation of iron minerals from gangue minerals during the grinding process. Subsequently, iron minerals can be recovered through magnetic separation. The fluidization self-magnetization roasting technology demonstrates significant potential in achieving the green and clean utilization of siderite.