Properties Of Coke Research Articles

Formation and evolution of coke of pyrolytic volatiles of low-rank coal on the carbon-based catalysts

The catalytic upgrading of coal pyrolysis volatiles is an effective technique to achieve clean and efficient conversion of low-rank coal. However, a major problem in this process is catalyst deactivation caused by coke deposition. This study investigated the catalytic cracking effect of activated carbon and metal-modified activated carbon on coal pyrolysis volatiles. It also explained the physical and chemical properties of coke and its formation mechanism related to volatile cracking. The results indicate that phenolic oils, pitch, oxygen-containing compounds, and polycyclic aromatics are linearly related to the coke deposited on the surface of carbon-based catalysts. These compounds act as precursors and are easily transformed into coke via cracking, deoxidation, crosslinking, and polycondensation reactions when the cracking rate of volatiles does not match the hydrogen supply rate. The micro-morphology of coke is primarily composed of amorphous carbon, which is mainly found in pores ranging from 0.50 to 5.00 nm and on the outer surface of carbon-based catalysts. The chemical structure of coke primarily consists of large aromatic clusters containing at least six benzene rings and oxygen-containing cross-linking compounds with a high degree of graphitization and a low number of carbon structural defects. This results in an increase in radical concentration of carbon-based catalysts, as well as a decrease in combustion reactivity. The outcomes will aid in controlling coke deposition during catalytic cracking of pyrolytic volatiles of low-rank coal.

Relationship between coking properties measured by automatic Sapozhnikov plastometer with other measurements

ABSTRACT A Sapozhnikov plastometer is equipment that is commonly used, particularly in Asia, for measuring the contraction of the coal bed as well as the plastic layer thickness during the coking process. The relationship between the Sapozhnikov contraction X and the maximum plastic layer thickness Y values and other thermal rheology testing techniques is not fully understood. It leads to difficulties in the interpretation of data using different thermal rheology properties measurement techniques. In this work, a series of coal samples were analyzed in parallel using the automatic Sapozhnikov plastometer, the Gieseler plastometer, and the Ruhr dilatometer. The measurement results were compared to assist in the interpretation of data generated using different coal thermal rheology property measurement techniques. The Sapozhnikov X results are found not comparable due to the difference in sample particle size and testing conditions for component coals with the wide range of maximum mean reflectance (Ro), but a significant linear correlation on the contraction/expansion behavior between Sapozhnikov and Ruhr dilatation test is observed for experimental coal blends Ro between 1.00 and 1.20. Sapozhnikov Y results are linearly related to the melting range from both the Gieseler plastometer and the Ruhr dilatometer for all the experimental single coals and coal blends.

Investigating the coking performance of ethylene residue pitch components

Ethylene residue pitch (ETP, the heavy component in ethylene residue tar) is widely used as a preferred raw material for preparing petroleum-based artificial carbon materials characterized by high carbon content, high aromaticity, and low heteroatom (S, N) content. To investigate the coking properties of ETP, eight components of ETP (four soluble and four insoluble components) were obtained via extraction and separation using methanol, n-butanol, n-hexane, and dimethyl sulfoxide as solvents. The thermal conversion (temperature = 500 °C) and carbonization treatment (temperature =1400 °C) were carried out on each pitch component. The basic physical properties of ETP components were observed using infrared spectroscopy, thermogravimetric analysis, and 1H-NMR. The microstructure of the petroleum-based pitch coke was studied using polarizing microscopy, X-ray single crystal diffraction (XRD), Raman spectroscopy, and scanning electron microscopy. The aromaticity of the insoluble components in ETP was slightly higher than that of soluble components, and the insoluble components had slightly fewer branching chains than those in soluble components. The microstrength of the ETP coke obtained using insoluble components was higher than that obtained using soluble components, and the true density of ETP coke HS-C was as high as 2.0554 g/cm3.

Deadman Behavior and Slag–Iron–Coke Interaction of Low Carbon and Safety Blast Furnace: A Review

The elucidation of the deadman's behavior and the interaction between slag–iron–coke within the blast furnace hearth are essential for the realization of low‐carbon and safe production. In this review, the macrostate of the deadman, the interactions between slag–iron–coke, carburizing behaviors, and renewal mechanisms are comprehensively examined. First, the formation and state of the deadman, voidage, and the distribution of coke sizes within the blast furnace hearth are characterized. The average coke particle size ranges from 20 to 30 mm, and the deadman void fraction of 30–50%. Second, the interaction between slag–iron–coke as well as the occurrence state of the mineral layer at the interface within the deadman is elucidated. The ash composition and content of coke are the key factors affecting the slag–iron–coke interaction and interface phase composition. Third, the influence exerted by critical factors such as the physical properties of the carbon source, molten iron, and temperature on the carburizing behavior are analyzed, with the renewal mechanisms of the deadman also being disclosed. Finally, three future focal areas are proposed: characterization and intelligent monitoring of deadman permeability, analysis of slag–iron–coke properties and interface mineral layers control, and in‐depth analysis of deadman renewal and carbon carburization in molten iron. It is anticipated that the studies will enhance the comprehension of deadman behavior and the interactions between slag–iron–coke, thereby fostering the blast furnace's sustainable development.

Electrical Resistance as an Aggregate Characteristic of Coke Properties for Electrochemical and Coke Production

Electrical Resistance as an Aggregate Characteristic of Coke Properties for Electrochemical and Coke Production

Study on the Role of Additives in Calcination Desulfurization Process of High Sulfur Petroleum Coke

Due to the high sulfur content of high sulfur petroleum coke, sulfur-containing gas will be produced in the production process, reducing product quality and other problems, resulting in increased production costs and equipment corrosion. How to reduce the sulfur content of high sulfur petroleum coke is of great significance to improve the utilization rate of high sulfur petroleum coke and the sustainable development of related industries. In this paper, the desulfurization of high sulfur petroleum coke was carried out by using the additive-assisted high-temperature calcination method. It was found that the desulfurization effect of different kinds of desulfurization additives was different, among which MO1, MC2, MC1 desulfurization effect was better, and the desulfurization rate could reach 68%, 58%, 56%. After compounding the three desulfurizers, the desulfurization rate can be up to 75%, and then the influence of calcination temperature and time on the desulfurization rate was investigated. Finally, the physicochemical properties of petroleum coke before and after desulfurization were analyzed by X RD, FT-IR.

Study on coke properties in deadman of blast furnace

The coke particle size and porosity of the deadman can significantly influence the distribution of molten iron flow velocity in the hearth as well as carbon brick erosion. In this study, coke samples were collected from the deadman after a 1780 m3 blast furnace was shut down. The particle size, mechanical strength, microstructure, chemical composition, and degree of graphitisation of coke were analysed alongside the voidage distribution of the deadman. The average particle size and mechanical strength of coke gradually decreased along the vertical axis of the deadman. The average particle sizes of coke at the top and bottom of the deadman were 28.15 mm and 25.04 mm, respectively. The M25 of the coke at the top and bottom of the deadman were 87.9% and 79.1%, respectively. The basicity of the slag entering the coke was lower than that of the original slag due to alterations in its composition caused by the ash content in coke, resulting in a reduction in its basicity. The graphitisation degree of coke gradually increased from the top to the bottom of the deadman. The voidage of the deadman progressively decreases in a downward direction. At distances of 4.5 m and 1.5 m from the hearth bottom, the voidages in the central zone of the deadman were 36% and 27%, respectively. These results deepen our understanding of coke in the deadman.

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.

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.

Optimizing the performance of iron coke by coal blending: Insights from the metallurgical properties and structural characteristics

Iron coke has gained widespread attention for its advantages in carbon reduction and efficient resource utilization. However, the structure and strength of iron coke have constrained its further advancement. This study systematically explores the impact of different coal blending structures on the three-dimensional structure and tensile strength of iron coke through three-dimensional reconstruction technology. It highlights the improvement mechanism of 1/3 coking coal addition on the microstructure and metallurgical properties of iron coke. The study shows that the tensile strength of iron coke increases with the addition of coking coal, while lean coal exhibits the opposite trend. The addition of an appropriate proportion of 1/3 coking coal (20–22 %) enhances the tensile strength and mechanical strength of iron coke, reaching the level of second-grade coke. However, an addition exceeding 22 % leads to increased porosity and reduced strength due to the high volatile content. Finite element analysis demonstrates that stress is primarily localized in regions with thinner pore walls and at the iron-carbon interface, and the aggregation effect of iron particles further causes stress concentration. Iron coke reactivity initially diminishes and subsequently rises with the addition of 1/3 coking coal, and it shows a linear negative correlation with the strength after reaction. Structural evolution reveals that the addition of 1/3 coking coal reduces the orderliness of carbon microcrystals, thereby increasing the active sites for gasification reactions. Meanwhile, the initial reduction followed by an increase in the specific surface area of iron coke can impact adsorption sites, thereby influencing reaction activity. These findings not only provide a new understanding of the structure-performance relationship of iron coke but also offer practical guidance for iron coke production.

Enhanced electrochemical performance of N, F co-doped and etched needle coke-based lithium-ion battery anode materials by NF3 plasma treatment

NF3 plasma treatments were used to improve the electrochemical properties of needle coke-based lithium-ion battery (LIB) anode materials. The effects of the NF3 plasma treatments on the chemical, structural, and morphological properties of the needle cokes were evaluated with various analyses, and simultaneous heteroatom doping coupled with surface etching was identified. With these effects, N and F functional groups and micropores were generated on the surfaces of the needle cokes. The NF3 plasma-modified needle cokes were analyzed with LIB performance tests, and considerable enhancements were observed in the discharge capacities, rate capabilities and cycling stabilities. The resulting nitrogen functional groups and micropores improved the lithium storage capacities and rates by providing lithium-ion adsorption sites. The fluorine functional groups enhanced the cycling stability by forming LiF-based SEI layers. These effects of the NF3 plasma treatment on the electrochemical properties were proven with analytical techniques, and mechanisms for the overall process were suggested based on the results. The NF3 plasma-treated needle cokes are promising materials for fast charging LIB anodes with high stabilities and competitive discharge capacities.

The Influence of Organic and Inorganic Additives on the Specific Electrical Resistance of Coke

This study aimed to evaluate the effect of both inorganic (boron carbide nanopowders and silicon carbide (carborundum) and organic lean (petroleum coke) additives on the quality of coke produced in a laboratory furnace, as well as on its electrical properties. Analyzing the results of the quality assessment of the obtained coke, it can be argued that the addition of a fixed amount (0.25-0.5 wt.%) of non-caking nanoadditives allows to regulate the process in the plastic state in order to increase the coke strength. This modification affects the coke quality and has a significant dependence on the grade composition of the coal charge. The use of nanoadditives is especially important for coal charges with poor coking properties. Adding 5% of petroleum coke to the coal charge leads to an increase in the gross coke yield by 1.2-1.3%; a decrease in coke ash content by 0.2-0.3%; an increase in the total sulfur content in coke by 0.15-0.23%; deterioration in both mechanical (P25 − by 0. 1-0.6%; I10 − by 0.1-0.2%) and coke strength after the reaction (CSR - by 0.6-1.0%), coke reactivity (CRI - by 0.2-0.3%), as well as structural strength (SS by 0.3-0.4%), abrasive hardness (AH by 0.7-1.0 mg) and specific electrical resistance (ρ by 0.002-0.007 Om×cm). The obtained data may indicate an increase in the order degree of the coke structure and the appearance of a larger number of nanostructures. In addition, it should be noted that a sharper deterioration in blast furnace coke quality is observed when using a coal charge characterized by a lower coal content of the Concentrating Factory Svyato-Varvarynska LLC.

Influence of Raw Materials and Technological Factors on the Sorption Properties of Blast-Fuel Coke

The influence of raw material factors (component composition of batches, petrographic characteristics, indicators of proximate and plastometric analyses, granulometric composition) and technological factors (coking period, process temperature) on the sorption properties of the carbonized product (coke) was studied. Based on the research results, it is shown that such characteristics of coke as low humidity and ash, minimal yield of volatile matters, developed pore system and low cost make its use as a sorbent promising and economically justified. The obtained equations for predicting the sorption capacity by alkali and acid and adsorption activity by iodine, taking into account the content of vitrinite and the yield of volatile matters coal batch. They are characterized by high approximation coefficients r (0.912 and 0.927 and 0.937, respectively), so they can be recommended for predicting the indicated indicators.

Influence of Coal Compacting on the Properties of Metallurgical Coke

Influence of Coal Compacting on the Properties of Metallurgical Coke

A comprehensive investigation on the structural transformation and dissolution loss reaction of coke during gasification in CO2 atmosphere

The in-situ investigation of the structural transformation of coke during gasification can provide useful insights into its dissolution loss reaction in blast furnaces. In this study, the structural properties of coke are evaluated by analyzing its carbon matrix, pore distribution, and ash composition using scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), Raman spectroscopy, mercury intrusion porosimetry (MIP), and X-ray fluorescence (XRF) spectrometry. The pore evolution and carbon structural transformation during gasification in CO2 atmosphere are analyzed in-situ using synchrotron radiation SAXS-WAXS techniques for three coke samples prepared from coals with varying ranks. The strength and reactivity of coke are assessed based on its structure and dissolution-loss reaction mechanism during gasification. The results indicate that the high breakage resistance index (M13) of coke is attributed to the interlocking of bent aromatic carbon layers with AD/AG less than 1.837. The amorphous structures characterized by A(VL+VR+SL+S)/AD higher than 0.935 in coke serve as the initiation site of reaction with CO2, leading to a decrease in the fractal dimension (DS) and interlayer spacing (d002) as well as an increase in the stacking width (La). Subsequently, the etching of the carbon microcrystals and the dissolution loss of defective carbon structures alternately occur during gasification. The rough pore surface with DS more than 2.91 hinders the CO2 diffusion, while the carbon matrix with AD/AG more than 2.269 effectively decreases the coke reactivity index (CRI) of coke. Overall, the findings of this study can offer a theoretical foundation for coke quality evaluation and effective optimization of iron-making processes.

Steam reforming of diethyl ether, ethanol and n-butanol with varied functionality and carbon chain impacts evolution of reaction intermediates and coking behaviors

Molecular structures of organics play key roles in determining the tendency of coking and property of coke through governing reaction intermediates formed. Diethyl ether (DEE) can be produced from etherification of ethanol and has same carbon number with n-butanol (butanol), while they may show distinct coking behaviors in steam reforming (SR). Herein, SR of DEE, ethanol and butanol over Ni/SBA-15 catalyst were performed, aiming to probe impacts of ether functionality and length of carbon chain of the alcohols on coke formation. The results indicated that cracking of DEE formed CxHy* species and unsaturated ketone intermediates, serving as precursors of coke. Dissociative adsorption of butanol formed abundant CxHy* species even from 100 °C, due to its longer carbon chain and lower oxygen content. In comparison, abundant oxygen-containing intermediates were generated from degradation of ethanol and reactions with steam. Abundant CxHy* species from DEE and butanol prompted formation of more coke than that from ethanol (60.6 % of coke in the catalyst for DEE, 66.8 % for butanol and 32.9 % for ethanol). Moreover, the coke from SR of ethanol was thermally less stable than that from DEE or butanol, due to the involvement of more oxygen-containing intermediates, which resulted in more aliphatic coke of amorphous form in ethanol reforming. Additionally, the coke from DEE reforming was more defective with carbon nanotube form of thick walls and little internal cavity. The coke produced from butanol reforming was more graphitic and mainly in carbon nanotube form of smooth surface. Varied abundance of CxHy* and ketone species in reforming of DEE and butanol created such a difference.

Впровадження технології трамбування на діючих коксових батареях

DOI: 10.31081/1681-309X-2024-0-2-14-28 Specialty 161. U.D.C. 662.74.2 IMPLEMENTATION OF TAMPING TECHNOLOGY AT OPERATING COKE OVEN BATTERIES © S.O. Kravchenko, Ph.D. in Technical Sciences (STATE ENTERPRISE "STATE INSTITUTE FOR DESIGNING ENTERPRISES OF COKE OVEN AND BY-PRODUCT PLANTS'' (SE "GIPROKOKS''), 61002, 60 Sumska str., Kharkiv, Ukraine), D.V. Miroshnychenko, Doctor of Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine), V.V. Koval, Ph.D. in Technical Sciences (STATE ENTERPRISE “UKRAINIAN STATE RESEARCH INSTITUTE FOR CARBOCHEMISTRY (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine), M.O. Solovyov, Ph.D. in Technical Sciences, S.Y. Abdullin, S.G. Grankin (SE "GIPROKOKS'') The article is devoted to verification of ensuring the appropriate economy and efficiency of coke production while reducing the level of consumption of scarce raw materials in order to optimise production in the current conditions of a coke-chemical enterprise. It is shown that the production of blast furnace coke using the technology of tamping the coal charge allows the use of a large amount of cheap gas coal without reducing the quality of the resulting blast furnace coke. However, despite the fact that this coking technology has been in use for a long time, the literature data on the impact of increasing the loading density on coke quality parameters is insufficient, contradictory and outdated. This article describes the main technical solutions for the conversion of an existing coke oven battery from the bulk coking chamber loading technology to the tamped coal cake loading technology and presents the results for the reconstructed coke oven battery. This project was developed and implemented by SE “GIPROKOKS” and HuDe. The economic and technological indicators of coke quality as a result of the conversion of the existing coke oven battery to the technology of loading a tamped coal cake were considered and compared with the parameters of its operation using the technology of bulk loading of coking chambers. It is shown that during the control period of observations (19 months) of the enterprise's operation, the mechanical strength of M25 coke increased on average from 85.2 to 87.4 %; post-reaction strength CSR – from 48.9 to 53.9 %; at the same time, the abrasion index M10 decreased from 8.0 to 5.9 %, and the reactivity CRI – from 38.0 to 37.2 %, respectively, when working using the tamping technology compared to the bulk method. In addition, the coke obtained by using the charge tamping method is characterised by lower values of ash and total sulphur content. Keywords: coke oven battery, charging, bulk (gravity) method, tamping technology, coal cake, coke properties. Corresponding author S.O. Kravchenko, e-mail: sa_kravchenko@giprokoks.com

Compressive strength and thermal properties of ferro coke prepared by cold pressing method

Compressive strength and thermal properties of ferro coke prepared by cold pressing method

Rapid quantitative analysis of petroleum coke properties by laser-induced breakdown spectroscopy combined with random forest based on a variable selection strategy.

Driven by the "double carbon" strategy, petroleum coke short-term demand is growing rapidly as a negative electrode material for artificial graphite. The analysis of petroleum coke physicochemical properties has always been an important part of its research, encompassing significant indicators such as ash content, volatile matter and calorific value. A strategy based on laser-induced breakdown spectroscopy (LIBS) in combination with chemometrics is proposed to realize the rapid and accurate quantification of the above properties. LIBS spectra of 46 petroleum coke samples were collected, and an original random forest (RF) calibration model was constructed by optimizing the pretreatment parameters. The RF calibration model was further optimized based on variable importance measures (VIM) and variable importance in projection (VIP) methods. After variable selection, the elemental spectral lines related to ash content, volatile matter and calorific value modeling were screened out, thus initially exploring the correlation between these properties and elements. Under the optimized spectral pretreatment method, VI threshold and model parameters, the mean relative error (MREP) of the prediction set of ash content, volatile matter and calorific value were 0.0881, 0.0527 and 0.006, the root mean square error (RMSEP) of the prediction set of ash content, volatile matter and calorific value were 0.0471%, 0.6178% and 0.2697 MJ kg-1, respectively, and the determination coefficient (RP2) of the prediction set was 0.9187, 0.9820 and 0.9510, respectively. The combination of LIBS technology and chemometric methods can provide powerful technical means for the analysis and evaluation of the physicochemical properties of petroleum coke.

Study on the interaction and coking characteristics of low-sulfur meager coal and medium-high sulfur fat coal during co-carbonization process

To expand the scope of coking coal resources and realize the efficient utilization of different types of coking coals, medium-high sulfur fat coal (FC1, FC2) and low-sulfur meager coal (MC) were selected to explore the influence of co-carbonization process on the final coke properties. Using 13C NMR, Raman and FTIR characterization, it is found that FC1 has a higher content of methylene and aromatic bridge carbon, multiple aromatic structure of 3–5 benzene ring, strong branching degree and hydrocarbon generation ability than FC2, which promote FC1 to produce more liquid phase products in the thermoplastic stage, form higher mobility and better fuse with MC. Comparing the properties of coke with different ratios, it is found that the proportion of MC added in FC1 could reach 60%, the cold-state strength of coke was improved and the deterioration of thermal-state strength was unobvious. When the amount of MC in FC2 is 40%, better coke performance can be obtained. This is mainly due to the fact that the actual volatile released during the pyrolysis of FC1 and FC2 combined with MC is higher than the calculated value, this promoted the pyrolysis of Car-Cal/O and inhibited the pyrolysis of Cal-Cal and Car-Car, resulting in more intermediate molecular weight aromatic nuclei and higher 3–5 membered ring structure content in the thermoplastic process, thus improving the coke quality.