Metallurgical Technology Research Articles

STUDY OF THE MODES OF RECOVERY AND DESTRUCTIBILITY OF CHROME BRIQUETTES UNDER CURRENT AND THERMAL LOADS

For an objective assessment of the recoverability of the resulting oxidized materials and deciphering the physico-chemical characteristics of their reduction processes occurring during the smelting of carbonaceous ferrochrome, special studies are needed. In this regard, the kinetics of the briquette reduction process has been studied in this article, which is extremely important for understanding the mechanism of carbothermic reduction in order to improve metallurgical technologies using coated materials. During the study, 6 different variants of briquettes with chromium ore and various types of carbon reducing agents were studied, such as China coke, Shubarkolsky special coke, Borlinsky coal and Shubarkolsky coal. The degree of chromium reduction was studied in the Tamman furnace by thermogravimetric method at temperatures of 1200; 1300; 1400; 1500; 1600 ° C for 1 hour. This article also provides calculations to determine the degree of reduction of chromium and iron using the Yander and Gistling-Brownstein equations. Of the six briquette variants, the best results in studying the kinetics of reduction of chromium ore raw materials were obtained using briquettes № 1, 3, 5. The study emphasizes the critical importance of understanding the reduction and destructibility modes of chromium briquettes to optimize the melting processes of carbon ferrochrome. The conclusions from this study are key to the development of both scientific understanding and practical applications in the metallurgical industry. This article summarizes the main results and meanings of the authors’ research, emphasizing its contribution to improving the efficiency and quality of carbon ferrochrome production through the systematic study of reduction behavior in chrome ore briquettes. Keywords: ferrochrome, chrome briquettes, coal, coke, degree of reduction, Yander equation, Gistling-Brownstein equation.

Advanced Processes in Metallurgical Technologies

The production of metals and their alloys will continue to increase in the coming years, mainly due to the growing demand for these products [...]

Towards green steel-energy and CO2 assessment of low carbon steelmaking via hydrogen based shaft furnace direct reduction process

Under current stringent climate policies, the iron and steel industry, as a major contributor to industrial CO2 emissions, urgently needs the development of low-carbon metallurgical technologies. This work focuses on the hydrogen-based shaft furnace process, which can utilize green energy to significantly reduce CO2 emissions. This work combines the hydrogen-based shaft furnace CFD model, regression equations, and Aspen Plus model to develop a multi-gas source DR (Direct Reduction) plant model. This combination significantly reduces computation time while maintaining predictive accuracy. The transformation from COG (Coke Oven Gas)-DR to H2-DR plant was studied, showing that the top gas circulation process greatly reduces the net carbon input of the entire DR plant. However, the energy consumption of electrolytic hydrogen production limits the transformation of COG-DR plant to H2-DR plant. The process CO2 emissions depend largely on electrical energy footprint. Under traditional electrical energy footprint, the CO2 emissions of H2-DR-EAF (Electric Arc Furnace) route are about four times those of the COG-DR-EAF route. Only when using green source energy does the H2-DR-EAF route achieve the lowest CO2 emissions among all routes, at 344 kg/tls, which is 79 % lower than that of the BF (Blast Furnace)-BOF (Basic Oxygen Furnace) route.

The application of green hydrogen in iron ore smelting under the target of carbon neutralization

Currently, green development and sustainable development have become a global consensus. In March 2023, the Intergovernmental Panel on Climate Change (IPCC) released the sixth comprehensive assessment report Climate Change 2023, which pointed out that greenhouse gas emissions are currently at the highest level in human history, and the global temperatures has been about 1.1 higher than that before industrialization. In July, 2023, the government of China also emphasized that the construction of ecological civilization in China has entered a critical period with carbon emission reduction as the focus. According to the survey, the steel industry in China has the highest carbon emission in manufacturing industry, and it is also one of the most important areas for China to deal with climate change. Based on the basic principle of blast furnace iron making, this paper first analyzes the causes of high emissions in the steel industry, and draws the conclusion that hydrogen metallurgy technology must be developed to achieve low-carbon development; Then, depending on different energy endowments, the differences in metallurgical technology between China and other countries are analyzed, and brief conclusions and suggestions are given on the basis of analyzing the challenges faced by low-carbon development of Chinas steel industry. This study provides insights into the importance of hydrogen metallurgy technology and enhance our understanding of how to achieve low-carbon development in Chinas iron and steel industry.

Current Status and Future Trends of Green Metallurgical Technology

Current Status and Future Trends of Green Metallurgical Technology

An annealing-free method for processing high-moisture iron-containing sludge of metallurgical production

The purpose of this study was to study the possibility of producing high-strength briquettes from high-moisture iron-containing slimes by hydration with quicklime (chemical dehydration) in combination with dolomite dust from a degusting system and carbon-containing pulverized materials and developing a drainless technology for the production of complex self-healing briquettes. The physicochemical conditions of the hydration process, temperature and time parameters of the process were studied, and the choice of active dehydrating materials significantly increased the degree of hydration of the composite system and their optimal ratios, and the period of the beginning and end of self-hardening were determined. The conditions of combining the processes of dehydration, and self-hardening with the processes of melding, when applying external pressure to a hardening mixture in a meld to obtain a coated material in the form of a briquette in one technological cycle are considered, which is one of the main provisions of the scientific novelty of the proposed method. Optimal conditions for the production of high-strength briquettes suitable for metallurgical production technologies, excluding the stages of thermal drying and firing, have been established, and a set of strength properties occurs in the air. The method allows obtaining a self-healing dipped material by introducing a carbon-containing reducing agent into a slurry-lime self-hardening mixture. Cheap waste pulverized limestone and dolomite roasting wastes are used as a dehydrating material, and pulverized carbonaceous materials (coke and coal screenings) are used as a reducing agent. Unlike well-known technical solutions, the proposed technology and the method incorporated in it eliminates the storage of iron-containing sludge in a sludge storage facility and allows you to organize a drainless scheme of non-annealing and the production of complex self-healing iron-containing material for the production of steel and rolled products. The technology will make it possible to organize production for the processing of high-moisture iron-containing sludge, pulverized calcium- and magnesium-containing and carbon-containing pulverized waste and also solves the problems of environmental pollution and land allocation for the storage of industrial waste.

Potential regulation strategy enables ferrocene as p-type redox mediator for direct regeneration of spent LiFePO4 cathode

Conventional metallurgical technologies for recycling cathode materials from retired Li-ion batteries go against carbon neutrality owing to massive material input and energy consumption. Although featuring with simplified process, direct regeneration technology still fails to bypass high-temperature driving forces for Li+ compensation of degraded cathodes. Herein, chemical re-lithiation strategy mediated by ferrocene is proposed to directly regenerate the Li-deficient spent cathodes. Ferrocene and its derivatives, the so-called p-type redox mediators, can be oxidized spontaneously from neutral molecules to stable cations under ambient conditions, allowing them to function as electron donors. Meanwhile, lithium salts serve as Li+ donors to ensure charge neutrality of the cathode lattice. The effects of solvation and substituent are thoroughly investigated to precisely regulate the potential of a series of ferrocene-based reductants. Chemical re-lithiation is driven thermodynamically by the intrinsic potential gap between ferrocene and degraded cathodes, thus fundamentally realizing a rapid lithiation reaction (taking less than 20 min at 25 °C), while avoiding the involvement of high-temperature operation. Diverse characterizations have been performed to explore the Li+-electron concerted re-lithiation mechanism. The regenerated LiFePO4 cathode demonstrated comparable Li+ storage capability to commercial cathode. Life-cycle analysis verifies the economical and environmental superiority of our chemical re-lithiation strategy to metallurgy in practical industry. The thermodynamically spontaneous chemical re-lithiation provides competitive options for greener recycling of retired batteries in the future.

The road to carbon neutrality in the metallurgical industry: Hydrogen metallurgy processes represented by hydrogen-rich coke oven gas, short-process metallurgy of scrap and low-carbon policy

Abstract With the acceleration of global industrialization, the concentration of carbon dioxide is increasing in the atmosphere, and its negative impacts have seriously affected all walks of human life, so achieving carbon neutrality has become an urgent task for achieving sustainable development. As an important energy-intensive industry, the metallurgical industry occupies an important position in the global carbon-neutral agenda. In China, the metallurgical industry is actively researching and developing a new green metallurgical model of “replacing carbon with hydrogen”, exploring the feasibility of utilizing renewable energy sources to produce hydrogen from electrolysis to reduce iron ore, and at the same time utilizing hydrogen-rich coke oven gas to get rid of the over-reliance on coke; at the same time, the government’s policies provide support and incentives to elevate sustainable development and technological innovation in the metallurgical industry. support and incentives to elevate sustainable development and technological innovation in the metallurgical industry. Against this background, this paper describes the key initiatives taken by the metallurgical industry in the process of achieving carbon neutrality, including the metallurgy using hydrogen processes using hydrogen-rich coke oven gas as a source of reducing gas, short-process metallurgy of scrap, and technology that reduce emissions and save energy. Through case studies and policy analyses of new green metallurgy, this study demonstrates the potential and achievements of the metallurgical industry in achieving global carbon neutrality. It concludes with a call for the metallurgical industry to continue to strengthen innovation and work with governments and academia to pave the way toward carbon neutrality. Through new metallurgical technologies, improved energy and resource efficiency, and sustainable development, the metallurgical industry will make a significant contribution to the goal of global carbon neutrality.

High temperature/low speed sliding wear behavior of Ni-Cr-W matrix composites against IC10 pin

Ni-Cr-W matrix cermet composites were prepared using powder metallurgical technology, and their microstructures, phase compositions, and mechanical properties were determined. Specifically, the tribological performances of the Ni-Cr-W composites were evaluated at a speed of 0.5 mm/s from room temperature to 800 °C, and their friction-reducing mechanism was clarified. The results showed that the NiCrW/Al2O3/Ag composite had the highest mechanical strength, with a 94.5 % increase in tensile strength compared to NiCrW/Al2O3. The NiCrW/Al2O3/SrCO3 composite exhibited the best high-temperature tribological performance because the chemical reaction on the friction surface generated new lubricating phases consisting of NiO, WO2, WO3, and Sr2CrO4. These acted synergistically lubricate and anti-wear with the Al2O3, Cr2O3, and NiCr2O4, and formed a continuous glaze layer on the wear surface. Furthermore, the multiple roles of nano-alumina in the obtained composite and its service in friction were discussed.

Data Sets Formation on the Physical Properties of Oxide Scale Components for Theoretical Assessment of Efficiency Parameters of Laser Cleaning of Carbon Steels and Related Processes

There is a need in machine-building industries nowadays to automate technologies, in particular, laser ones, to remove surface oxide layers – mill scale, rust – from steel products/pieces in order to improve the energy effectiveness of processing. Herewith, a theoretical assessment method for the intensity of heating of the oxide layer and the phase transition in it can be used to optimize laser cleaning (LC) of the steel surface. To realize this, it is possible to use some calculation and modeling procedures that require, as a first step, the data collection and verification on the temperature-dependent properties of iron-containing condensed phases, as possible components contained, in particular, in scale, which is typically widespread into various metal products. In this regard, the formation of database for characteristics of oxide scale components by the way of selection of information on thermophysical (including optical) properties of the components mentioned and of steel base, which are required for a reliable calculation of the thermal efficiency parameters of the technology for laser cleaning of carbon steels, as well as such actively developed related technologies as laser cutting, drilling, coating remelting, etc., was chosen as the task of our research. An analytical overview of published experimental data made it possible to systematize information on a number of transport and other physical properties of iron-containing components at ambient pressure, including thermal conductivity (k) and diffusivity (a), density ρ, irradiation absorptance and integral emissivity in the temperature range from T ≈ 298 K to the melting temperatures of oxide and metal phases and above them. At the same time, a preliminary thermochemical estimation shows (on the calculated data) the existence of such thermodynamically stable forms of the condensed phase in the heating spot of scale layers during its LC at the melting point and above it, as Fe3O4, FeO, and Fe, which is consistent with known experimental data. Comparison of the values of a calculated by us (using the published values of k, ρ and molar heat capacity and using extrapolation in the high-temperature region) for the types of scale components under consideration with a set of experimental values of this parameter in current literature revealed the presence of differences for both oxide and metal phases. These new values make it possible to fill in a gap in the temperature range T = 1600–1800 K that existed in the data on the thermal diffusivity. The value of a = (0.83–0.92)·10–6 m2/s was also calculated for liquid iron oxide for the T ≈ 1800 K, which was not measured experimentally, that, obviously, prevented modeling of not only laser surface processing, melting and cleaning of steels, but also calculations in the field of metallurgical and other technologies, which are characterized by the presence of iron oxide melts during heating.

Experimental investigation into corrosion effect on buckling and low-cycle fatigue performance of high-strength steel bars

The reinforcement in marine RC structures will inevitably be corroded under long-time erosion of chloride ions, which will weaken steel mechanical properties and then structural seismic resistance. The new metallurgical technology is adopted for manufacturing high-strength steel bars (HSSB), but that may affect the corrosion resistance of steel bars at the same time. This paper experimentally investigates the effects of corrosion on monotonic and low-cycle fatigue properties of HSSB HTRB600 and normal strength steel bars (NSB) HRB400E. The HRB400E and HTRB600 steel bars were corroded to different corrosion rates by electrochemical accelerated corrosion technique. The monotonic tensile and compressive, as well as low-cycle fatigue tests of corroded steel bars were conducted to investigate the effects of corrosion on steel mechanical properties, of which corrosion levels (0–20% target corrosion mass loss), slenderness ratios (L/D=6, 8, 10, 12) and strain amplitudes (2%, 4%) are considered. Test results show that, the corrosion morphology of steel bars under electrochemical accelerated corrosion is basically consistent with that observed under natural corrosion. Compared with uncorroded HRB400E and HTRB600 steel bars, 20% corrosion mass loss leads to 38% and 35% decrease in tensile strength, as well as 33% and 28% reduction in buckling stress, respectively. The HTRB600 steel bars present slightly superior monotonic tensile and compressive corrosion resistance than HRB400E steel bars. Corrosion obviously decreases the low-cycle fatigue (LCF) life of steel bars, resulting in reductions of 44% and 36% in LCF life at 20% corrosion mass loss for HTRB600 and HRB400E steel with a L/D of 6, respectively. Moreover, the HTRB600 steel bars present more significant corrosion degradation in total hysteretic dissipated energy, compared with HRB400E steel bars. The combined effect of corrosion and inelastic buckling further exacerbates the deterioration of LCF performance of steel bars. The corresponding deterioration models are proposed to determine the LCF life and energy dissipation capacity of corroded steel bars.

Ashwamedha Yagya: Gupta Dynasty

The Ashwamedh Yagya, an ancient Vedic ritual extensively documented in Indian epics and Vedic texts, holds significant historical importance. This ritual, detailed in texts such as the Rig Veda and Yajur Veda, is also elaborated upon in the Mahabharata’s Ashwamedha Parva. Despite its ancient prominence, the frequency and depth of the Ashwamedh Yagya declined over time after the Gupta dynasty. Archaeological evidence, including inscriptions and rock edicts, provides substantial insights into the practice of the Ashwamedh Yagya. The Gupta dynasty's inscriptions, particularly those issued by rulers like Samudragupta and Chandragupta II, provide critical genealogical and historical data regarding the Ashwamedh Yagya. These inscriptions mention the performance of the ritual and highlight its significance during their reigns. Samudragupta, in particular, revived the Ashwamedh Yagya and issued commemorative Ashwamedha coins, which serve as crucial historical artifacts. These coins depict the ritual’s elements and were used to honor the Ashwamedh Yagya, showcasing the advanced metallurgical technology of the Gupta period. Furthermore, archaeological discoveries, including inscriptions and rock edicts, illuminate the extensive practice of Ashwamedh Yagya among the Gupta rulers to build the nation and culture against foreign attackers of the time. Overall, the Ashwamedh Yagya's practice and its documentation through archaeological findings, inscriptions, and coins reveal its extensive significance in ancient Indian history, particularly within the Gupta dynasty, for reviving Vedic culture through Ashwamedh Yagya. \\

A review of direct recycling methods for spent lithium-ion batteries

The increasing demand for lithium-ion batteries (LIBs) in new energy storage systems and electric vehicles implies a surge in both the shipment and scrapping of LIBs. LIBs contain a lot of harmful substances, and improper disposal can cause severe environment damage. Developing efficient recycling technology has become the key to the sustainable growth of the LIBs industry. At present, the extraction of high-value materials from spent LIBs using pyrometallurgical and hydrometallurgical processes is most usual. However, they consume a lot of energy and lead to secondary environmental pollution, which is not consistent with the idea of creating a green circular economy. Direct recycling has been suggested as a possible alternative method of dealing with the spent LIBs under non-destructive conditions in the further. Compared with traditional metallurgical technologies, direct regeneration significantly reduces the consumption of energy and chemical reagents, and has a high selectivity for certain metal ions, which is environmentally friendly. However, direct cycling is still in its infancy with many scientific and technological barriers. In this review, we first consider the necessity of recycling spent LIBs, and then summarize the failure mechanisms of degraded cathode materials in order to choose a corresponding regeneration method. The direct cycling technologies, including hydrothermal, solid-state, eutectic medium and electrochemical regeneration are introduced separately from the perspective of the experimental process, operating parameters, regeneration principles, advantages, and effects. Furthermore, the current problems and potential future research on the direct cycling of spent LIBs are also discussed.

Exploring Mediterranean Connections and Iron Age Entanglements

Despite the conventional association with sophisticated metallurgical technologies, the Iron Age has long fallen between the two academic poles of prehistoric and classical archaeology. The more recent invention of a self-consciously ambivalent terminology of ‘proto-historic’ and ‘proto-urban’ features represents an attempt by mostly European archaeologists to give the Iron Age socioeconomic substance in its own right, while at the same time also underscoring the ambiguity of the period. Moreover, as the Iron Age has since become synonymous with notions of state formation and urbanization, its deep evolutionist roots have only become more evident.

Innovation of Course System for Metallurgical Technology Specialty Combining Engineering With Study

With the continuous development of social economy and science and technology, my country's education has also undergone various changes. In order to meet the requirements of the current society, metallurgical technology education in higher vocational colleges must improve the teaching quality from the innovative curriculum system. Vocational colleges themselves are places for cultivating talents for social enterprises, so only by perfecting the curriculum system can the comprehensive ability of students be improved from diversified education. the effective innovation of the curriculum system requires the construction of the higher vocational curriculum system in the mode of combination of work and study. This article mainly focuses on the analysis and research on the innovation of the combined engineering and course system for metallurgical technology majors.

Modulating Fe/P ratios in Fe-P alloy through smelting reduction for long-term electrocatalytic overall water splitting

Owing to strong Fe-P interaction that differs the electron distribution beneath metal/phosphide interface of Fe-P alloy, the charge transfer of Fe-P alloy has been accelerated during the electrocatalytic oxidation process and improved the efficiency and durability of overall water splitting. In this work, a novel metallurgical technology in combination with smelting reduction and Single Roller Melting Spinning (SRMS) for the purpose of electrochemical overall water splitting where High-phosphorus Oolitic Iron Ore (HPOIO) has been directly used as the main raw material is developed for preparing amorphous Fe-P alloys strips. The rational modulation on the Fe/P ratio can alter the crystal structure and crystallinity of Fe-P alloy, favor electron transfer, and further trap the positively charged H+. The obtained FeP electrocatalyst exhibits 436 and 527 mV at 10 mA cm−1 with Tafel slopes of 102.3 and 77.2 mV dec−1 for HER and OER in 1.0 mol/L KOH solution, respectively, especially with long-term stability (∼207 h for HER and ∼42 h for OER). Specifically, the DFT calculation displaying structural advantages and componential superiorities exhibited that P in Fe-P amorphous alloy regulated by systematic P addition optimization might increase the energy density in the Fermi level. Furthermore, the phosphorus content brought about high active surface areas, low impedance, and variable reaction paths-caused low reaction energy barriers with the improved amorphicity and absorption and desorption of intermediates, thereby boosting the overall water splitting activity. This study displays a novel strategy to develop Fe-P amorphous alloy for the stable and efficient overall water splitting.

Mechanical properties of high-nitrogen steel produced via selective laser melting using mechanically alloyed and spheroidized powders

In recent years, the development of additive technologies has been one of the priority tasks in the sector. Primarily, additive technologies enable the effective implementation of various design and engineering ideas in high-tech industries, such as the aircraft industry, engine technology, and rocket engineering. The expanded range of standardized materials for additive technologies will facilitate their integration into large-scale production. Of significant interest is the potential use of nitrogen-containing heat-resistant powder alloys to produce complex-shaped aircraft parts using additive technologies. This paper describes the complete process of obtaining samples from powders of alloys with superequilibrium nitrogen content using the selective laser melting (SLM) method. Four different compositions of high-nitrogen steels were obtained through mechanical alloying. Subsequently, the powders of these steels underwent processing using the plasma spheroidization method to be utilized in the SLM process. The SLM method was also employed to produce samples for mechanical tests. Throughout each stage of the process, the powders were thoroughly analyzed. One of the most critical parameters was the nitrogen content in the resulting powders. At each subsequent production stage, its proportion decreased, yet it remained at the superequilibrium content level of 0.13–0.44 wt. %. The mechanical tests confirmed that the alloys fabricated by the SLM method are not inferior in terms of their properties compared to those obtained using classical metallurgical technologies.

Application of industrial waste in foundry and metallurgical technologies. Experience of the department of Metallurgical Technologies and Equipment

Application of industrial waste in foundry and metallurgical technologies. Experience of the department of Metallurgical Technologies and Equipment

Prospects for green steelmaking technology with low carbon emissions in China

AbstractThe steel industry is a major source of CO2 emissions, and thus, the mitigation of carbon emissions is the most pressing challenge in this sector. In this paper, international environmental governance in the steel industry is reviewed, and the current state of development of low‐carbon technologies is discussed. Additionally, low‐carbon pathways for the steel industry at the current time are proposed, emphasizing prevention and treatment strategies. Furthermore, the prospects of low‐carbon technologies are explored from the perspective of transitioning the energy structure to a “carbon–electricity–hydrogen” relationship. Overall, steel enterprises should adopt hydrogen‐rich metallurgical technologies that are compatible with current needs and process flows in the short term, based on the carbon substitution with hydrogen (prevention) and the CCU (CO2 capture and utilization) concepts (treatment). Additionally, the capture and utilization of CO2 for steelmaking, which can assist in achieving short‐term emission reduction targets but is not a long‐term solution, is discussed. In conclusion, in the long term, the carbon metallurgical process should be gradually supplanted by a hydrogen–electric synergistic approach, thus transforming the energy structure of existing steelmaking processes and attaining near‐zero carbon emission steelmaking technology.

On the opportunities and prospects of the dept. of Metallurgical Technologies and Equipment in training specialists in additive technologies in the production of iron and steel castings

On the opportunities and prospects of the dept. of Metallurgical Technologies and Equipment in training specialists in additive technologies in the production of iron and steel castings