Metallurgical Coke Research Articles

Use of forestry waste as an alternative raw material for generating metallurgical coke

Use of forestry waste as an alternative raw material for generating metallurgical coke

Sediment microbial fuel cells capable of powering outdoor environmental monitoring sensors

In this study, Sediment Microbial Fuel Cells (SMFCs) prototypes have been developed to operate under open-air conditions and power sensors for environmental monitoring. Two SMFCs with a volume of 50 l each, consisting of two types of anodic materials – graphite and coke, were operated on-field for over a year. The electrical outputs have been recorded and compared with the measured environmental parameters such as temperature, light illumination, atmospheric pressure, humidity, etc. The statistical analysis of the obtained data shows that temperature changes between 0 and 14 °C do not affect the power achieved. On the contrary, the sunlight irradiation showed a second-order polynomial correlation with the current generated by the SMFCs, increasing the latter during the days. The cathode reactions significantly impacted the power density achieved by both explored SMFCs and the system's sustainability. The metallurgical coke is suggested to be used as an inexpensive and convenient anode material for SMFCs giving compatible results to the widely used graphite.

Pyrometallurgical Reduction of Copper Slag with Biochar for Metal Recovery

Large amounts of slag are generated during pyrometallurgical processing in copper production. Due to the presence of valuable elements, the improper disposal of huge quantities of copper slag produced, results in significant loss of resources as well as environmental issues. Analyses of the copper slag show that it contains valuable metals, particularly copper and nickel. In this work, four biochars were employed as fossil-free reducing agents to recover valuable metals from the slag. Reduction experiments were performed in a vertical furnace at temperatures 1250, 1300 and 1350 °C for 60 min in order to investigate the effect of temperature. Moreover, the effect of time on reduction progress was studied at 1250 °C and the concentrations of CO and CO2 in the off-gas were measured with a gas analyzer. Copper slag was reacted with metallurgical coke for comparison and the products were analyzed with EPMA and LA-ICPMS. The results revealed that reduction rapidly progresses to the formation of metal alloy within 10 min. Valuable metals like copper, nickel and arsenic were the first to be reduced to the metal phase. As reduction time increased, iron was also reduced and combined with the metal droplet. The use of biochar as reductant was shown to be more effective than coke especially at lower temperatures. In addition, thermodynamic modelling was performed with FactSage and HSC and compared with the experimental results. The simulations with HSC showed the sequence of reactions taking place and the calculations by FactSage were in agreement with the experiments.Graphical

Experimental Research on the Metallurgical Properties and Cokes’ Solution-Loss Reaction of Lump Ores in the H2O-CO2 Atmosphere in the Hydrogen-Rich Blast Furnace

Experimental Research on the Metallurgical Properties and Cokes’ Solution-Loss Reaction of Lump Ores in the H2O-CO2 Atmosphere in the Hydrogen-Rich Blast Furnace

Study on the Influence of Industrial Coke Oven Size on the Quality of Metallurgical Coke

The large-scale coke oven is a developing trend in coking technology, and the influence of the industrial coke oven size on the quality of metallurgical coke needs to be revealed. Under the same raw coals and blending ratios, metallurgical cokes were obtained from top-loading coke ovens with carbonization chamber heights of 6 and 7 m, respectively. The macroscopic quality and microstructure of the refined metallurgical cokes were comprehensively tested. The results showed that the conventional cold and thermal strength indexes of Coke-7m were better than those of Coke-6m. The comprehensive thermal strength at multiple temperatures further showed that the thermal strength advantage of Coke-7m was mainly manifested at low temperatures (1050 and 1100 °C) or a high temperature (1300 °C), where the solution-loss reaction mode of coke tended to be the “uniform reaction model” or “unreacted core model”. At medium temperatures, the solution-loss reaction mode tended to be the “gradient reaction model”, which had a greater destructive effect on the thermal strength of coke. At this time, the thermal strengths of the two cokes were close. Microstructure characterization revealed that industrial coke oven size mainly affected the carbon structure of coke but had little effect on pore structure. The advantage of Coke-7m regarding carbon structure is an important reason for its superior macroscopic quality compared to Coke-6m.

Exploring the metallurgical coke thermal properties in viewpoint of experiment and molecular simulation

The Chinese standard method of GB/T 4000–2017 was unable to accurately measure the coke thermal properties in the large blast furnace. Therefore, the coke compressive strength (CCS) test at a high temperature was designed to examine the coke thermal properties. Then, the large-scale coke model (sp2C17421sp3C6579) was established. After, the ReaxFF molecular dynamics simulations were implemented to mimic the coke solution loss (CSL) and the CCS at the high temperature. It was found that the adsorption energy and the diffusion energy of micropores were greater than those of mesopores and macropores, indicating that the CSL reaction mainly happened in the coke micropore. It was discovered that the CSL reaction mechanism was the sp3 C oxidization mechanism with the transient state of ketene structure. And, it was detected that the CCS process was divided into the plastic deformation, the instantaneous fracture and the elastic deformation and yield, which was caused by the local reconstruction, the overall folding and the center stretching of carbon layer, respectively. By comparing simulated results with experiments, it was proved that obtained mechanisms were valid. The proposed experimental and simulated methods provided a novel method to measure and understand the coke thermal properties.

PROMISING TYPES OF HEAT STORAGE ELEMENTS FOR REGENERATIVE AIR HEATERS OF BLAST FURNACES

The paper considers the problem of improving the efficiency of operation of blast furnace air supply systems, which are equipped with regenerative heat exchangers with fixed refractory nozzle for heating hot blast. The existing methods of improving the performance of air heaters are analyzed. It is shown that further growth of thermal efficiency of regenerative heat exchangers by optimization of operation parameters or replacement of nozzles is impossible without increasing the overall parameters. As a perspective measure the use of heat storage elements with phase transition is proposed, where as a fusible insert compounds with a certain melting point are used, which corresponds to the operating modes of blast furnace air heaters. They have found application for heat storage in solar systems. Due to the "residual" thermal effect, the nozzles accumulate additional heat. This will increase the heat capacity of the heat exchanger and increase the hot blast heating temperature without changing the dimensional parameters. Operating conditions of air supply systems of blast furnaces are characterized by high temperature level, which is 1200–1350 °С, significant flow rates and speeds of hot and cold coolants, their increased pressure. Therefore, there is a question of choosing appropriate heatacumulative elements taking into account their properties and operating parameters of blast furnaces. Operation of such nozzles has revealed a number of problems, the solution of which requires additional research. For this purpose it is necessary to carry out modeling of quasi-stationary heat-exchange processes in the nozzle chamber of regenerative air heaters in order to select chemical compounds or their mixtures, which meet the operating conditions of blast furnace air supply systems, and to determine the optimal combinations of nozzle materials. Application of this technology will make it possible to obtain higher hot blast heating temper- ature, reduce metallurgical coke consumption or increase blast furnace productivity.

Comparison of Bio-Coke and Traditional Coke Production with Regard to the Technological Aspects and Carbon Footprint Considerations

In a world facing the challenges of climate change, it is imperative to prioritize the search for sustainable technical solutions. This study focuses on evaluating the environmental impact of using bio-coke compared to traditional metallurgical coke, employing Life Cycle Assessment (LCA) as the evaluation tool. Bio-coke, produced from a blend of coking coals enriched with biomass, offers greater environmental potential than traditional coke due to a reduced share of non-renewable raw materials. The steel and coking industries are significant contributors to carbon dioxide emissions. LCA provides a comprehensive assessment of the environmental impact of bio-based additives, considering raw material deliveries, the coking process, application in metallurgy, and product end-of-life disposal. The analysis results indicate that the use of biomass additives leads to lower greenhouse gas emissions compared to coke production without bio-additives. Given the urgency of addressing global warming and the increasing demand for sustainable energy sources, this study’s findings can advocate for bio-coke as a more environmentally friendly alternative to traditional coke in the steel industry.

Isothermal reduction and comparative analysis of reaction kinetics of sponge iron produced from hematite-charcoal reaction using non-contact direct reduction method

The challenge of making sponge iron, or direct reduced iron (DRI), is hard to overstate. These are a key feed for metallurgical operations while iron extraction sets these limits, which include scarcity of metallurgical coke, poor environmental impact, and high production cost. Thus, the non-contact direct reduction process of DRIs has the potential to significantly reduce carbon deposition and CO2 emission from the ironmaking process. This work produced sponge iron from commercially acquired hematite ore using an alternative reducing agent (i.e. charcoal) under specified isothermal conditions. Comparative analysis of reaction kinetics models including Ginstein−Brounshtein and Shrinking core models was also performed to ascertain the resistances that control the reaction rate for reduction degree up to 98.1%. The reduction kinetics were found to be described by reaction control time and activation energies based on a shrinking core model as the reduction time lasted for 120 min at temperatures 843–1273 K. At temperatures above 973–1073 K, the rate-limiting step was found to be solely an interfacial chemical reaction process, with an apparent activation energy of 196.1 kJ/mol. In addition, a slowing trend was observed for iron ore sample sizes 10–20 mm as a result of ash layer infiltration around the inner-core structure of the DRI metal matrix. The DRI morphological characteristics were performed using Scanning Electron Microscopy (SEM) and Electron Dispersive Spectrometry (EDS) to ascertain the mineralogical and morphological properties of the DRI samples. The XRF analysis confirms that the raw iron ore sample is hematite. Its iron content is 70.04% metallic iron (TFe) which has 83.59% Fe2O3 The SEM/EDS image also revealed the presence of micropores on the DRI morphology. This indicates that the reduction ratio and swelling extent rise with the temperature and time. This happens for all DRI sizes. However, the EDS result confirms the presence of gangue elements within the DRI metal matrix and mineralogical structure. The DRI contains very high silicon content up to 33.90%. So, a fluxing experiment is needed using limestone (CaCO3) or quicklime (CaO) quicklime to remove gangue (silicate, aluminate) from the DRI matrix. At the set reduction temperatures, the largest metallization degree of 93.05% at 1273 K for a reduction time of 120 min was achieved. This showed that the overall reduction process still follows the expected chronological order since the NDR process uses CO gas from preheated charcoal. This makes DRI be produced from raw hematite under non-contact reduction bases. Therefore, the NDR technique offers a viable option for sponge iron production in modern-day iron and steelmaking processes.

Enabling CO2 neutral metallurgy for ferrochromium production using bio-based reducing agents

The metallurgical industry is a major source of anthropogenic greenhouse gas emissions. This study explores the replacement of fossil-reducing agents with potentially CO2-neutral bio-based reducing agents. Since reducing agents remove oxygen bonded with metal oxides present in the ore, they are a necessity for the production of metallic elements. The investigated metal is chromium, a major part of stainless steel, and therefore a highly relevant element for the transition from a fossil-based energy system to a renewable one. The state-of-the-art smelting reduction and pre-reduction process followed by subsequent smelting using various reducing agents are investigated in this article. The obtained products, metallurgical efficiencies, energy consumption and off-gas generation were compared. While the products produced with bio-based reducing agents are comparable with the reference trials using metallurgical coke regarding the major components in the metal, the concentration of detrimental phosphorus is significantly higher using bio-based reducing agents. The metallurgical efficiency of the process is comparable to the usage of bio-based reducing agents and coke. However, the energy consumption and the generation of off-gas is higher, when coke is replaced by bio-based reducing agents.

Structure and morphology of chars and activated carbons obtained from thermal treatment of coal and biomass origin materials, including their wastes: Results from the ICCP Microscopy of Carbon Materials Working Group

This paper describes the evaluation of petrographic textures in char and activated carbon derived from coal, coal by-products and biomass, formed during carbonization and activation processes. This work represents the results of interlaboratory exercises from 2016 to 2022 of the Microscopy of Carbon Materials Working Group in Commission III of the International Committee for Coal and Organic Petrology. The interlaboratory exercises were run on photomicrograph samples. For textural characterization of carbon materials, the existing American Society for Testing and Materials (ASTM) classification system for metallurgical coke was applied. Morphological differences were evaluated in 29 carbon material types, including 22 char samples, and 7 activated carbon (AC) samples obtained experimentally using conventional direct/indirect and microwave heating technologies. This approach gives an extended view on the identification of microporous carbons, and how a certain heat treatment develops a certain optical texture and structure in a raw material. The requested evaluation of carbon materials was related to their porosity, origin, extent, and characteristics, which are particular to each carbon material type. Because carbon matrices can form a wide range of optical textures during heat treatment it is important to demonstrate which carbon occurrences will have a crucial role in industrial applications dominated by adsorption phenomena.The interlaboratory exercises included 17 participants from 14 laboratories. Four sets of digital black and white and colour photomicrographs were distributed, which in total comprised 184 fields of different types of carbon material. The results were evaluated based on four levels: (i) optical texture (isotropic/anisotropic), (ii) optical type and size (punctiform, mosaic, fiber, ribbon, domain), iii) morphology (porous, non-porous/massive), and (iv) particle origin (precursor type).The statistical method applied to evaluate the results was based on “raw agreement indices”. Comparative analyses of the average values of the level of overall agreement showed homogeneity in the results, the mean value was 89%, with a minimum value of 87% and a maximum value of 91% for those who participated in at least three out of four exercises.

Study of Palm Oil Shell Utilization as Metallurgical Coke with Variation of Bondcrete Additive

Coke, an essential ingredient in the steel and metallurgical industries, is typically derived from bituminous coal. However, in Indonesia, where bituminous coal is rare, coke production is dependent on coal imports due to the high moisture content of local coal. An alternative approach is to use biomass, such as palm oil processing waste, for "biomass coke" to produce a more environmentally friendly coke with lower greenhouse gas emissions. Palm kernel shell waste rich in lignocellulose proved suitable for this purpose due to its compressive strength and carbon content. Pyrolysis, a technique for creating porous micro-structured carbon from palm kernel shells, was used to produce this coke substitute, offering a more sustainable energy source with a lower carbon footprint than fossil fuels. Bio-coke exhibits low moisture content (5.84%) and ash content (13.20%) due to the moisture and ash reduction effects of bondcrete adhesive during combustion. It also demonstrates substantial compressive strength (14 mPa), a high calorific value (6795 cal/g), and a favorable pore structure with a large surface area, indicating a positive influence of bondcrete adhesive on coke properties without compromising energy potential.

Cooperative treatment and resource utilization of municipal solid waste by industrial coke ovens: Effects of doping ratio and management

For the collaborative treatment and resource utilization of an industrial coke oven on municipal solid waste (MSW), this study used MSW to prepare refuse-derived fuel (RDF). The influence of different mix ratio between RDF and coal on coking products was considered, and technical and economic analyses were conducted. The results showed that under the low mixture ratio (3%), the pyrolytic carbon obtained basically met the class III standard of metallurgical carbon. In the experiment of medium mixture ratio (25%, 30%, 35%), the product contained a certain amount of calorific value, lower than that of the metallurgical coke. It might be that the ash content increased, and such product can be used for civil coke or chemical coke. When the mixture ratio was 100%, the calorific value of pyrolysis carbon was 7.53 MJ/kg, representing 25.7% of the calorific value of ordinary coke. The gas production rate of the discharged gas was 0.35, and the calorific value is 14.0 MJ/kg, reaching 73.6% of the coke oven gas. Under the condition of no coal input, the MSW was converted into usable energy. The results demonstrated that coke oven pyrolysis with 100% RDF addition is the most feasible way to recycle resources and energy.

Evaluation of component interface quality in 3D micro-CT images of metallurgical coke

Metallurgical coke is a crucial component in the production of steel worldwide. It is a porous composite material, created by conversion of metallurgical coal in a coke oven. A key property of metallurgical coke is its strength, and there is evidence that poor interface quality between the two key components of coke can have deleterious effect on coke strength. Here we create small samples of coke and image them using high resolution 3D micro-CT, with pixel size of approximately \(8\,\mu\)m. We use a Gabor filter, combined with morphology techniques to isolate the different components in the samples. We then develop a measure, called excess porosity to quantify the quality of the interfaces between components. This measure enables us to highlight problem interactions between components.

Sulfur migration during co-pyrolysis of high sulfur coking coal with fat coal and lean coal

Desulfurization remains a critical yet challenging aspect of producing high-quality metallurgical coke through pyrolysis. Previous studies have suggested that introducing hydrogen-rich gases may improve sulfur removal efficiency. To further explore this approach, we investigated the effects of volatile matter on sulfur migration during co-pyrolysis of high-sulfur coal (SC) with both fat coal (FC) and lean coal (LC). Our findings indicate that most sulfur is transferred into the coke during pyrolysis, with sulfide and pyrite being relatively easy to decompose, while thiophenes and sulfones tend to be thermally stable. Co-pyrolysis with FC significantly decreased sulfur content in the final coke product, while co-pyrolysis with LC resulted in higher sulfur content. The comparative analysis points to the beneficial influence of volatile matter in promoting desulfurization through enhanced sulfur transfer into the gas phase and reduced sulfur fixation with nascent coke. These findings offer practical guidance for coke-making industries to optimize coal blending scheme and to achieve efficient desulfurization during coke-making.

Influence of Coal Compacting on the Properties of Metallurgical Coke

Influence of Coal Compacting on the Properties of Metallurgical Coke

Аналіз та огляд прогнозів світового виробництва металургійного коксу

DOI: 10.31081/1681-309X-2024-0-1-3-7 Specialty 161. U.D.C. 338.27:662.749.2 ANALYSIS AND REVIEW OF FORECASTS OF WORLD METALLURGICAL COKE PRODUCTION © S.A. Kravchenko, PhD in Technical Sciences, S.V. Chaplianko, PhD in Technical Sciences "STATE INSTITUTE FOR DESIGNING ENTERPRISES OF COKE OVEN AND BY-PRODUCT PLANTS'' (SE "GIPROKOKS''), 61002, 60 Sumska str., Kharkiv, Ukraine) The article considers and analyses the volumes of global iron and steel production in 2019-2023. It is shown that during this period it had fluctuating trends: the deviation between the minimum and maximum values was 109 million tonnes (7.7 %) for iron and 112 million tonnes (5.7 %) for steel. Domestic steel production in 2019-2021 was characterised by an increase of 1.1 million tonnes (5.2 %) in iron and fluctuations (the deviation was 0.8 million tonnes, i.e. 3.7 %) in steel, and a sharp decrease of 14.8 million tonnes (69.7 %) in steel. t (69.8 %) for iron and 15.1 million tonnes (70.6 %) for steel in 2022 and a further decrease of 0.4 million tonnes (6.2 %) for iron and 0.1 million tonnes (1.6 %) for steel in 2023 is due to the consequences of Russia's armed aggression against Ukraine. The article considers and analyses the volumes of global production of metallurgical coke in 20192021. It is shown that during this period it had fluctuating trends: the deviation was 21 million tonnes (3.0 %). The volume of coke production in China in 2020-2023 increased at an average annual growth rate of 2.2, 2.4, and 3.8 %, respectively. Domestic production of metallurgical coke in 20192021 was characterised by a decrease in volume by 0.44 million tonnes (5.2 %), and a rapid decrease by 5.6 million tonnes (59.0 %) in 2022 is also due to the consequences of armed aggression. Separate forecasts for global metallurgical coke production in the short and long term are considered. It is shown that there is no consensus on the development of global coke production. The most negative scenario is a decline in global coke production to $84.016 billion (USD) in 2029, while the most positive is an increase to $325.78 billion in 2034. In 2024, on average, the global metallurgical coke market will be around $106 billion according to negative forecasts and around $205 billion according to positive forecasts. Given the World steel Association's weak positive outlook for global steel production, as well as the existing increase in coke production in China in 2020-2023 and the planned expansion of coke production capacity in India and Brazil, a restrained positive outlook for global coke production is most likely (for 2024 and beyond). Keywords: cast iron, steel, metallurgical coke, coke-chemical production, analysis, forecast. Corresponding author S.V. Chaplyanko, e-mail: chaplianko_sv@ukr.net

INVESTIGATING RELATIONSHIPS BETWEEN INTRINSIC PROPERTIES, PREPARATION PARAMETERS OF COAL AND COKE QUALITY: A SYSTEMATIC LITERATURE REVIEW

The purpose of this study is to review some of the key research concepts related to metallurgical coke. As the research landscape for coke metallurgy is evolving, researchers are increasingly interested in the effects of the intrinsic properties of coal, coal preparation parameters, and the technological conditions of coke production on the quality of metallurgical coke. As part of this review, a specific protocol, content analysis and thematic coding of cases of the “Preferred Reporting Items for Systematic Review and Meta-Analyses” method were used to investigate the simultaneous effect of these two parameters on the quality of coke in selected journal articles. A review of 118 articles was conducted, including their abstract, introduction, methodology, and results. According to the results of this study, coal blends and coal particle sizes have a direct effect on the three sections of coke mechanical properties, coke texture, and coke reactive properties. Reviewing various articles has shown that the presence of fatty coals in smaller size distribution, combined with largersized weak coals, leads to the formation of a stronger structure in the produced coke. However, this does not guarantee an improvement in the coke reactivity parameters. On the other hand, increasing the blending ratio of coking coals in the final mixture for producing normal-sized coke (dimensions smaller than 3 millimetres) improves the coke reactivity parameters. Studies investigating coke structure have demonstrated that a cohesive mosaic structure in high-quality cokes results from well-distributed maceral blends of coking coals with optimal size distribution among other coals.

Effect of inertinite-rich coal on metallurgical coke strength and porous microstructure

Effect of inertinite-rich coal on metallurgical coke strength and porous microstructure

Replacement of Concrete Aggregates with Coal-Derived Flash Graphene.

Each year, the growth of cities across developing economies in Asia, Africa, and Latin America drives demand for concrete to house and serve their burgeoning populations. Since 1950, the number of people living in urban areas has quadrupled to 4.2 billion, with another predicted 2.5 billion expected to join them in the next three decades. The largest component of concrete by volume is aggregates, such as sand and rocks, with sand as the most mined material in the world. However, the extraction rate of sand currently exceeds its natural replenishment rate, meaning that a global concrete-suitable sand shortage is extremely likely. As such, replacements for fine aggregates, such as sand, are in demand. Here, flash Joule heating (FJH) is used to convert coal-derived metallurgical coke (MC) into flash graphene aggregate (FGA), a blend of MC-derived flash graphene (MCFG), which mimics a natural aggregate (NA) in size. While graphene and graphene oxide have previously been used as reinforcing additives to concrete, in this contribution, FGA is used as a total aggregate replacement for NA, resulting in 25% lighter concrete with increases in toughness, peak strain, and specific compressive strength of 32, 33, and 21%, respectively, with a small reduction in specific Young's modulus of 11%. FJH can potentially enable the replacement of fine NA with FGA, resulting in lighter, stronger concrete.