Evaluation of High Mean of Maximum Reflectance(MMR) coals for coke making through selective crushing

Evaluation of High Mean of Maximum Reflectance(MMR) coals for coke making through selective crushing | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of High Mean of Maximum Reflectance(MMR) coals for coke making through selective crushing Karthik G This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7248294/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Selective fine crushing of high Mean Maximum Reflectance (MMR) Australian coking coals—Sarji, Peak Down, and PLV—was studied to enhance coke quality and reduce wall pressure during coking. Each coal was crushed to varying degrees (-3.15 mm at 80%, 85%, 90%, and 95%) and carbonized in a pilot-scale coke oven. The resulting coke was evaluated for wall pressure, CSR, CRI, porosity, volatile matter, ash content, and power consumption. Results showed that increasing fine coal content, especially in Sarji coal, significantly reduced wall pressure (from 7.25 to 3.89 kPa) and porosity, while improving CSR (from 62.48 to 69.39) and reducing CRI (from 25.62 to 21.83). These benefits were linked to better particle packing, gas permeability, and reduced swelling. Additionally, coke from finer blends exhibited lower volatile matter and ash, enhancing thermal stability. Power consumption remained stable, highlighting process efficiency. Selective fine crushing proves to be an effective method for producing high-quality coke from high MMR coals. Materials Engineering Selective fine crushing wall pressure High MMR Coke quality Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Coal samples were crushed to specific particle sizes, blended, and carbonized at 1250°C for 18.5 hours in a pilot-scale coke oven, with gas pressure monitored at the oven center. Fine crushing of high coking pressure coals improves the permeability of the plastic layer, facilitating gas escape during carbonization and lowering internal pressure, regardless of whether the crushing is done before or after blending. This enables higher proportions of such coals to be used without compromising coke pushing performance. However, finer particles reduce bulk density, which lowers productivity and coke strength. Excessive fine crushing also causes carbon buildup on oven walls, increasing energy consumption and leading to issues like hard pushing and coke sticking. As temperature rises, the pressure drop (∆P) increases to a peak (∆P_max), then falls as re-solidification begins, with ∆P_max decreasing as particle size becomes finer. [ 1 – 3 ] Reducing the moisture content of coal increases its bulk density in the coke oven, which contributes to improved coke quality. When high coking pressure coal is blended with slightly caking coal, the resulting internal gas pressure is lower than the average of the individual pressures of the separate coals. Generally, internal gas pressure rises with increasing bulk density. However, raising the proportion of slightly caking coal in the blend helps lower the overall gas pressure. Importantly, in dry coal charging, coking pressure levels comparable to those in wet charging can be maintained by adjusting the blend to include a higher ratio of slightly caking coal. [ 2 ] This study examined three types of Australian coking coals—hard, prime, and soft—and found that coal properties vary with particle size. Ash content increases with larger particle sizes, while volatile matter decreases. The distribution of macerals also changes across size fractions; finer particles show higher Vitrinite content, which is associated with improved coking performance, while coarser fractions contain more inertinite and mineral matter. The Crucible Swelling Number (CSN), a key indicator of coking behavior, improves as particle size decreases. Additionally, higher Vitrinite content in finer coal fractions correlates with greater maximum fluidity, reinforcing the role of particle size in influencing coal's coking potential and overall quality [ 3 ] Recent studies have examined how bulk density influences coke quality, particularly in relation to the addition of residue oil to coal. Maximum bulk density is achieved at a residue oil content of 0.5% with 8% moisture; beyond this level, bulk density declines. Across four types of coal, increasing bulk density by around 100 kg/m³ has been shown to enhance the Coke Strength after Reaction (CSR) by approximately 5%. Higher bulk density also leads to coke with more small-sized pores, resulting in a texture with broader bridges and greater porosity, both of which contribute to improved CSR. However, changes in bulk density have minimal impact on the Coke Reactivity Index (CRI), highlighting that while CSR benefits from optimized bulk density, CRI remains largely unaffected. [ 4 ] Research on coal particle size and its effects on gas pressure and coking behavior has shown that reducing the mean particle size leads to a significant drop in gas pressure within the plastic coal layer. Finely crushing high-pressure coking coal enhances gas permeability, as indicated by a lower maximum pressure drop (∆Pmax). This fine crushing also reduces both internal gas pressure and the maximum power current needed during coke pushing, indicating lower energy demand. These findings highlight the critical role of particle size in controlling gas flow and energy efficiency during the coking process, stressing the importance of optimizing particle size for high-pressure coking coals. [ 5 ] Several studies have investigated the relationship between coal thermoplastic behavior and wall pressure generation in coke ovens, highlighting the significance of contraction phenomena measured by the Koppers-INCAR test. These studies suggest that events occurring during the thermoplastic state of coal can influence semicoke contraction and contribute to excessive wall pressure. Specifically, Koppers-INCAR curves for certain problematic coals exhibit an intermediate expansion peak during the final phase of thermoplasticity, indicating potential links between contraction behavior and pressure generation. However, the correlation between Koppers-INCAR contraction values and Gieseler maximum fluidities is either absent or weak, often depending on the coal's volatile matter content. This suggests that while contraction behavior may influence wall pressure, it cannot be directly associated with Gieseler fluidity (or viscosity). Consequently, these two properties—contraction and fluidity—do not show a strong combined correlation with wall pressure, indicating that they should be considered independent factors when evaluating coal behavior in coke ovens. [ 6 – 11 ] Studies on the modification of coal with hydroxypropyl cellulose (HPC) components have shown that pyridine extraction reduces O-functional groups in both soluble and insoluble components, potentially decreasing hydrogen bonding. In contrast, methanol extraction selectively moves O-functional groups into soluble components. Modification of non- or slightly-caking coal with pyridine-soluble HPC components increased fluidity compared to physical mixing with soluble components or HPC, suggesting a stronger effect from pyridine swelling. However, modification with MeOH-soluble components did not significantly alter fluidity. Additionally, chemically modified coals with pyridine-soluble components produced stronger coke than the original or physically mixed coals, although no significant difference in contraction behavior was observed during carbonization. [ 12 – 16 ] Methodology In this study, three Australian coals—PLV, Sarji, and Peak Down—were selected for lab-scale experimental trials aimed at reducing the wall pressure in a pilot coke oven, a key factor for high-pressure coking coals characterized by a higher Mean Maximum Reflectance (MMR). The pilot coke oven, with a capacity of 120 kg, was equipped with a load cell to measure the wall pressure during the carbonization process. The specific qualities and MMR values for each coal sample are summarized in Table 1. For the experimental trials, each coal sample was ground to a particle size of -3.15 mm, with varying proportions of coal particles finer than 3.15 mm, specifically 80%, 85%, 90%, and 95%. In each trial, 50 kg of the prepared coal sample was charged into the pilot coke oven, where it was carbonized for a period of 19 hours. After carbonization, the resulting coke was pushed out of the oven, and the pushing current was recorded. Simultaneously, the wall pressure during the carbonization process was measured for each coal sample. To maintain consistency, the moisture content of all coal samples was kept constant at 10% throughout the trials. Additionally, the bulk density of each crushed coal sample was noted prior to the experiments. This methodology allows for the evaluation of the impact of different coal qualities and particle sizes on both the wall pressure in the pilot coke oven and the pushing current required for coke removal. Results and Discussions Wall pressure with blending percent The experimental results for the three Australian coal samples—PLV, Sarji, and Peak Down—demonstrate significant findings related to wall pressure. As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, all measured wall pressures—Sarj coal wall pressure, peak down wall pressure, and PLV wall pressure—consistently decrease as shown in Fig. 1. Specifically, Sarji wall pressure drops from 7.25 kPa to 3.89 kPa, peak down from 5.98 kPa to 3.21 kPa, and PLV from 5.82 kPa to 3.41 kPa. This indicates that increasing the fine fraction of Sarji coal leads to reduced pressure on the oven walls during coking. The finer particles improve packing density and permeability, allowing better gas flow and minimizing pressure buildup. Additionally, Sarji coal may possess lower fluidity or swelling characteristics, which further reduces the tendency to generate wall pressure. Overall, the higher percentages of fine Sarji coal improve the coking behavior by producing a more stable and less expansive coke mass, thereby reducing mechanical stress on the oven walls. The decrease in wall pressure with increasing fine Sarji coal fraction is primarily due to improved particle packing and enhanced permeability within the coal charge. Finer Sarji particles fill voids between coarser grains, resulting in a denser, more uniform matrix that facilitates easier gas escape during coking, thereby reducing pressure buildup. Additionally, Sarji coal’s lower fluidity and swelling tendencies limit lateral expansion of the plastic layer, minimizing mechanical stress on the oven walls. This combination of better packing, improved gas flow, and reduced coal expansion leads to a more stable coke structure, effectively lowering wall pressure as the fine Sarji coal content increases. Coke quality with blending percent The quality of coke produced from the pilot coke oven was evaluated using the standard ASTM-D5341 methods, which assess both the Coke Strength After Reaction (CSR) and the Coke Reactivity Index (CRI). As shown in Figs. 2 and 3, a trend was observed where finer crushing of the coal resulted in an increase in CSR and a decrease in CRI. As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the Coke Strength after Reaction (CSR) shows a consistent upward trend across all measurement points—Sarji, Peak Down, and PLV. Specifically, Sarji CSR increases from 62.48 to 69.39, Peak Down from 63.41 to 67.35, and PLV from 62.37 to 68.97. This indicates a significant improvement in coke strength after exposure to CO₂, which is crucial for maintaining structural integrity in the blast furnace. The rise in CSR is primarily due to the improved packing and reduced porosity that comes with a higher proportion of fine particles, resulting in a denser and more cohesive coke structure. Additionally, Sarji coal likely has favorable coking properties—such as lower fluidity and volatile matter—which contribute to forming stronger, more thermally stable coke. The simultaneous decrease in CRI and increase in CSR confirms that the coke produced becomes both less reactive and more robust as the fine Sarji coal content increases. As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the Coke Reactivity Index (CRI) consistently decreases across all measurement points—Sarji, Peak Down, and PLV—indicating improved coke quality. Sarji CRI drops from 25.62 to 21.83, Peak Down from 25.40 to 21.60, and PLV from 26.26 to 22.39. This decline in CRI suggests that the coke becomes less reactive to CO₂, which is desirable for maintaining strength in the blast furnace. The improvement is likely due to better packing and reduced porosity from the increased fine content, as well as the intrinsic properties of Sarji coal—such as lower volatile matter and higher carbon content—which contribute to forming a denser, more thermally stable coke with lower reactivity. The observed increase in Coke Strength after Reaction (CSR) and concurrent decrease in Coke Reactivity Index (CRI) with increasing proportions of fine (-3.15 mm) Sarji coal in the blend can be attributed to improvements in the physical and chemical characteristics of the coke structure. The higher fine particle content enhances packing density and reduces porosity within the coke matrix, resulting in a denser, more cohesive structure that better resists mechanical degradation and gas attack. Additionally, Sarji coal’s favorable coking properties—such as lower fluidity, reduced volatile matter, and higher carbon content—contribute to forming coke with increased thermal stability and lower reactivity to CO₂. This combination leads to a coke product that is both stronger after reaction and less prone to degradation, which is essential for maintaining blast furnace performance. The simultaneous increase in CSR and decrease in CRI thus reflect the positive impact of fine Sarji coal on producing high-quality, robust coke. Coke proximate analysis with blending percent As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, both coke volatile matter (VM) and ash content show a consistent decrease across all sampling points—Sarji, Peak Down, and PLV as shown in Figs. 4 and 5. Coke VM drops significantly, with Sarji values declining from 1.61–0.92%, Peak Down from 1.65–0.94%, and PLV from 1.73–0.88%, indicating more complete devolatilization and improved coke maturity. Similarly, coke ash content decreases, with Sarji reducing from 14.18–13.15%, Peak Down from 14.89–13.45%, and PLV from 13.69–12.48%. These improvements are mainly due to the finer particle size and lower inherent VM and ash in Sarji coal, which enhance heat transfer and allow better control during carbonization. As a result, the coke produced is cleaner and more stable—favorable traits for efficient and high-quality blast furnace performance. The consistent decrease in coke volatile matter (VM) and ash content with increasing proportions of fine (-3.15 mm) Sarji coal in the blend can be attributed to the combined effects of particle size and coal composition on the carbonization process. The finer Sarji coal particles improve heat transfer efficiency within the coal charge, promoting more uniform and complete devolatilization, which reduces residual volatile matter in the resulting coke. Additionally, Sarji coal inherently possesses lower VM and ash content compared to the other coals, contributing to a cleaner coke product. The reduced ash content is also a result of the dilution effect as the finer Sarji coal replaces higher ash components in the blend. Together, these factors enhance coke maturity and stability by producing a denser, lower-impurity coke structure, which is advantageous for blast furnace operations by improving coke reactivity and mechanical strength. Coke porosity with blending percent As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the porosity of the resulting coke decreases steadily across all sampling points—Sarji, Peak Down, and PLV as shown in Fig. 6. Sarji porosity drops from 52–44%, Peak Down from 52.35–44.47%, and PLV from 52.15–44.25%. This reduction in porosity indicates a denser, more compact coke structure, which is beneficial for improving coke strength and reducing reactivity. The decline in porosity is primarily due to the finer particle size of Sarji coal, which allows for better packing and fewer voids during the coking process. Additionally, Sarji coal likely possesses coking properties that favor the formation of a more consolidated coke matrix. Lower porosity enhances the mechanical strength and stability of coke in the blast furnace, making it more resistant to degradation under load and during gas reactions. The steady decrease in coke porosity with increasing proportions of fine (-3.15 mm) Sarji coal in the blend is primarily attributed to enhanced particle packing and improved matrix consolidation during coking. The finer Sarji particles fill interstitial voids more effectively, resulting in a denser and more compact coke structure with fewer pores. This improved packing reduces the overall porosity by minimizing the formation of large void spaces within the coke. Additionally, the intrinsic coking properties of Sarji coal, such as its lower fluidity and favorable plasticity range, contribute to the development of a more consolidated and stable coke matrix. Lower porosity enhances the mechanical strength and thermal stability of the coke, making it more resistant to physical degradation and chemical reactions in the blast furnace environment. This structural densification ultimately leads to improved coke performance, supporting more efficient and reliable blast furnace operations. Coke pushing power consumption with blending percent : As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, power consumption during the coking process shows some fluctuation across different sampling points—Sarji, Peak Down, and PLV. Sarji power consumption increases from 230.5 kW to 226.6 kW, Peak Down shows a more significant increase from 259.2 kW to 263.3 kW, and PLV fluctuates between 224.6 kW and 225.9 kW. Overall, there is a slight increase in power consumption for Peak Down, while Sarji and PLV show stable or slightly reduced power usage. The variation in power consumption is influenced by the blend's impact on the coking process, where higher percentages of fine Sarji coal likely improve the packing and thermal conductivity, which can sometimes reduce the energy required for heating. However, the differences observed, particularly in Peak Down, may result from variations in the specific combustion characteristics of the coal and the required adjustments to maintain consistent heating. Fine Sarji coal may also lead to more efficient heat transfer, requiring less power in some areas while slightly increasing it in others due to its impact on the coking dynamics. The observed fluctuations in power consumption during coking with increasing proportions of fine (-3.15 mm) Sarji coal are influenced by the interplay between improved packing, thermal conductivity, and the intrinsic combustion characteristics of the coal blend. The finer Sarji particles enhance packing density, which can improve thermal contact between particles and promote more efficient heat transfer throughout the coal charge, potentially reducing the overall energy required for heating. However, variations in coal composition, particularly with Peak Down coal, may affect combustion behavior and the thermal profile within the oven, necessitating adjustments in power input to maintain consistent temperature control. Differences in volatile matter content, fixed carbon, and ash can alter the combustion kinetics, leading to localized increases or decreases in power demand. Consequently, while fine Sarji coal generally supports more efficient heat transfer and can lower power consumption, these benefits may be offset by the specific thermal and combustion dynamics of the blend components, resulting in the observed fluctuations. Conclusion The present study systematically evaluated the impact of selective fine crushing on high Mean Maximum Reflectance (MMR) Australian coals—Sarji, Peak Down, and PLV—for coke-making applications. The experimental investigations, carried out in a pilot-scale coke oven, revealed that increasing the proportion of coal particles finer than 3.15 mm notably improves coking behavior, particularly in reducing wall pressure and enhancing coke quality metrics. A progressive increase in the fine fraction of Sarji coal from 80–95% led to a consistent decline in wall pressure, indicating reduced mechanical stress on coke oven walls—a critical factor for the safe and efficient utilization of high-pressure coals. Correspondingly, the Coke Strength after Reaction (CSR) improved, and the Coke Reactivity Index (CRI) declined, signifying the production of stronger and less reactive coke suitable for high-performance blast furnace operations. The finer coal blends also contributed to lower coke volatile matter and ash content, as well as reduced porosity, yielding a denser and more thermally stable coke structure. These enhancements can be attributed to improved particle packing, permeability, and heat transfer efficiency during carbonization. Furthermore, power consumption during coke pushing remained stable or slightly reduced, indicating energy-efficient performance under optimized crushing conditions. Overall, the results affirm that selective fine crushing of high MMR coals, particularly Sarji, is an effective strategy to mitigate coking pressure-related challenges while simultaneously improving coke quality. This approach facilitates the broader utilization of high-reflectance, high-swelling coals in metallurgical coke blends, supporting more flexible and efficient coke oven operation without compromising structural integrity or coke performance. Declarations Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Author contribution Karthik G conceived and designed the experimental plan. Vikas u conducted the experiments, and Mrunmaya KP analyzed the results and contributed to data analysis and interpretation. Karthik G wrote the manuscript. All authors reviewed and approved the final version of the manuscript. References Seiji NOMURA, 1) Takashi ARIMA, 1) Atsushi DOBASHI 2) and Kazuhide DOI 3) , Nippon Steel Corporation, Environment & Process Technology Center, 20-1, Shintomi, Futtsu, Chiba, 293-8511 Japan. S. Nomura and T. Arima: Fuel, 80 (2001), 1307 Nakashima, Y. et al.: 2nd Int. Cokemaking Congr. London, UK, 1992, p.518 J. S. Atr. Inst. Min. Metal/., vo!. 91, no. 2. Feb. 1991. pp. ,53-61. B. K. Sahooa, *, B. Ghosha, **, P. K. Jhaa, ***, P. K. Pankaja, ****, S. K. Kushwahaa, *****, B. Chakrabortya, ******, K. K. Manjhia, *******, and N. Pradhana, ********, DOI: 10.3103/S1068364X21080068 Ramon Alvarez, Jose J. Pis, and Maria A. Diez Instituto National del Carbon INCAR, C.S.I.C, Apartado 73, Oviedo 33080, Spain Anna Marzec* and Sylwia Czajkowska Institute of Coal Chemistry, Polish Academy of Sciences, Sowinskiego 5, 44-102 Gliwice, Poland. Energy & Fuels 1997, 11, 978-981 Coking Pressure Seminar. Cokemaking Int. 1992, 4, 1-40. Marzec, A.; Alvarez, R.; Casal, D. M.; Schulten, H.-R. Energy Fuels 1995, 9, 834-840. Barriocanal, C.; Patrick, J. W.; Walker, A.; Walker, A. R. The Identification of Dangerously Coking Coals. In Coal Science; Pajares, J. A., Tascon, J. M. D., Eds; Elsevier: Amsterdam, 1995; Vol. 1, pp 989-992. Koch, A.; Gruber, R.; Cagniant, D.; Krzton, A.; Duchene, J. M. Fuel Process. Technol. 1995, 45, 135-153. Steyls, D. Cokemaking Int. 1992, 4, 31-33 Naoto TSUBOUCHI, 1) * Ryo NAGANUMA, 1) Yuuki MOCHIZUKI, 1) Hideyuki HAYASHIZAKI, 2) Takahiro SHISHIDO 3) and Atul SHARMA 4) . (2019), No. 8 © 2019 ISIJ 1396 ISIJ International, Vol. 59 (2019), No. 8, pp. 1396–1403 (2019) N. Okuyama, T. Shigehisa, Y. Nishibata, K. Matsudaira and M. Nishimura: Tetsu-to-Hagané, 92 (2006), 213 (in Japanese). P. R. Solomon, M. A. Serio, G. V. Despande and E. Kroo: Energy Fuel., 4 (1990), 42. F. Goodarzi and D. G. Murchison: Fuel, 51 (1972), 322. G. D. Cody, J. W. Larsen and M. Siskin: Energy Fuel., 2 (1988), 340. 5) L. M. Lucht and N. A. Peppas: Fuel, 66 (1987), 803. Table 1 Table 1 is available in the Supplementary Files section. Additional Declarations The authors declare potential competing interests as follows: Vikas U, Mrunmaya P Supplementary Files table.tif Table 1: Coal sample qualities and MMR Slide2.tif Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7248294","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":492910708,"identity":"c28b6b01-0933-4e45-82e1-668db4664148","order_by":0,"name":"Karthik G","email":"data:image/png;base64,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","orcid":"","institution":"Jsw steel ltd","correspondingAuthor":true,"prefix":"","firstName":"Karthik","middleName":"","lastName":"G","suffix":""}],"badges":[],"createdAt":"2025-07-30 04:21:48","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":true,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-7248294/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7248294/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":88105028,"identity":"74b28291-6867-45d3-8025-06b46d4c2631","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":54688,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/e8d2d6dcfd43591ef0b53a9a.png"},{"id":88105933,"identity":"3490275e-209f-41af-97fc-f60bd0bc5f2b","added_by":"auto","created_at":"2025-08-01 12:23:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":204571,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/e9bd00fa046acf7ffc86342e.png"},{"id":88105033,"identity":"84813ffb-cb77-419a-b295-c76b5e37647c","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":149844,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/cdbad07fd0fab2d52437415d.png"},{"id":88105040,"identity":"9cc92023-bba3-41aa-bd4e-f726d10e6bde","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":159745,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/16f048bc5ede278fa93d8c15.png"},{"id":88105936,"identity":"d3ffe9a5-7ab7-4539-a370-ca8a6f6cc730","added_by":"auto","created_at":"2025-08-01 12:23:54","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":187906,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/a551959c72567bece2961dca.png"},{"id":88105037,"identity":"022e9bfd-e3c4-4011-89e6-782f5a23d4b6","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":140045,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/5c86c6be6a6378df86bdb85b.png"},{"id":88107214,"identity":"a7af5ea2-31ec-48ad-9c79-ac82deddc65a","added_by":"auto","created_at":"2025-08-01 12:39:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1464540,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/6247b329-4fd8-436e-8fc7-5f42d5abae83.pdf"},{"id":88105029,"identity":"4ad7b7c7-dee9-4c5d-9bc0-85f8ac7499cb","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"tif","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":96526,"visible":true,"origin":"","legend":"\u003cp\u003eTable 1: Coal sample qualities and MMR\u003c/p\u003e","description":"","filename":"table.tif","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/d8f06630358ff27d3fdc895a.tif"},{"id":88105031,"identity":"598e7d9d-932f-487f-ba2a-054a5c400e2c","added_by":"auto","created_at":"2025-08-01 12:15:54","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":117434,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Slide2.tif","url":"https://assets-eu.researchsquare.com/files/rs-7248294/v1/f41f23fe91fabdf35c040e04.tif"}],"financialInterests":"The authors declare potential competing interests as follows: Vikas U, Mrunmaya P","formattedTitle":"\u003cp\u003eEvaluation of High Mean of Maximum Reflectance(MMR) coals for coke making through selective crushing\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCoal samples were crushed to specific particle sizes, blended, and carbonized at 1250°C for 18.5 hours in a pilot-scale coke oven, with gas pressure monitored at the oven center. Fine crushing of high coking pressure coals improves the permeability of the plastic layer, facilitating gas escape during carbonization and lowering internal pressure, regardless of whether the crushing is done before or after blending. This enables higher proportions of such coals to be used without compromising coke pushing performance. However, finer particles reduce bulk density, which lowers productivity and coke strength. Excessive fine crushing also causes carbon buildup on oven walls, increasing energy consumption and leading to issues like hard pushing and coke sticking. As temperature rises, the pressure drop (∆P) increases to a peak (∆P_max), then falls as re-solidification begins, with ∆P_max decreasing as particle size becomes finer. [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e–\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eReducing the moisture content of coal increases its bulk density in the coke oven, which contributes to improved coke quality. When high coking pressure coal is blended with slightly caking coal, the resulting internal gas pressure is lower than the average of the individual pressures of the separate coals. Generally, internal gas pressure rises with increasing bulk density. However, raising the proportion of slightly caking coal in the blend helps lower the overall gas pressure. Importantly, in dry coal charging, coking pressure levels comparable to those in wet charging can be maintained by adjusting the blend to include a higher ratio of slightly caking coal. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eThis study examined three types of Australian coking coals—hard, prime, and soft—and found that coal properties vary with particle size. Ash content increases with larger particle sizes, while volatile matter decreases. The distribution of macerals also changes across size fractions; finer particles show higher Vitrinite content, which is associated with improved coking performance, while coarser fractions contain more inertinite and mineral matter. The Crucible Swelling Number (CSN), a key indicator of coking behavior, improves as particle size decreases. Additionally, higher Vitrinite content in finer coal fractions correlates with greater maximum fluidity, reinforcing the role of particle size in influencing coal's coking potential and overall quality [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eRecent studies have examined how bulk density influences coke quality, particularly in relation to the addition of residue oil to coal. Maximum bulk density is achieved at a residue oil content of 0.5% with 8% moisture; beyond this level, bulk density declines. Across four types of coal, increasing bulk density by around 100 kg/m³ has been shown to enhance the Coke Strength after Reaction (CSR) by approximately 5%. Higher bulk density also leads to coke with more small-sized pores, resulting in a texture with broader bridges and greater porosity, both of which contribute to improved CSR. However, changes in bulk density have minimal impact on the Coke Reactivity Index (CRI), highlighting that while CSR benefits from optimized bulk density, CRI remains largely unaffected. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eResearch on coal particle size and its effects on gas pressure and coking behavior has shown that reducing the mean particle size leads to a significant drop in gas pressure within the plastic coal layer. Finely crushing high-pressure coking coal enhances gas permeability, as indicated by a lower maximum pressure drop (∆Pmax). This fine crushing also reduces both internal gas pressure and the maximum power current needed during coke pushing, indicating lower energy demand. These findings highlight the critical role of particle size in controlling gas flow and energy efficiency during the coking process, stressing the importance of optimizing particle size for high-pressure coking coals. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eSeveral studies have investigated the relationship between coal thermoplastic behavior and wall pressure generation in coke ovens, highlighting the significance of contraction phenomena measured by the Koppers-INCAR test. These studies suggest that events occurring during the thermoplastic state of coal can influence semicoke contraction and contribute to excessive wall pressure. Specifically, Koppers-INCAR curves for certain problematic coals exhibit an intermediate expansion peak during the final phase of thermoplasticity, indicating potential links between contraction behavior and pressure generation. However, the correlation between Koppers-INCAR contraction values and Gieseler maximum fluidities is either absent or weak, often depending on the coal's volatile matter content. This suggests that while contraction behavior may influence wall pressure, it cannot be directly associated with Gieseler fluidity (or viscosity). Consequently, these two properties—contraction and fluidity—do not show a strong combined correlation with wall pressure, indicating that they should be considered independent factors when evaluating coal behavior in coke ovens. [\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e–\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eStudies on the modification of coal with hydroxypropyl cellulose (HPC) components have shown that pyridine extraction reduces O-functional groups in both soluble and insoluble components, potentially decreasing hydrogen bonding. In contrast, methanol extraction selectively moves O-functional groups into soluble components. Modification of non- or slightly-caking coal with pyridine-soluble HPC components increased fluidity compared to physical mixing with soluble components or HPC, suggesting a stronger effect from pyridine swelling. However, modification with MeOH-soluble components did not significantly alter fluidity. Additionally, chemically modified coals with pyridine-soluble components produced stronger coke than the original or physically mixed coals, although no significant difference in contraction behavior was observed during carbonization. [\u003cspan additionalcitationids=\"CR13 CR14 CR15\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e–\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e"},{"header":"Methodology","content":"\u003cp\u003eIn this study, three Australian coals—PLV, Sarji, and Peak Down—were selected for lab-scale experimental trials aimed at reducing the wall pressure in a pilot coke oven, a key factor for high-pressure coking coals characterized by a higher Mean Maximum Reflectance (MMR). The pilot coke oven, with a capacity of 120 kg, was equipped with a load cell to measure the wall pressure during the carbonization process. The specific qualities and MMR values for each coal sample are summarized in Table\u0026nbsp;1.\u003c/p\u003e\u003cp\u003eFor the experimental trials, each coal sample was ground to a particle size of -3.15 mm, with varying proportions of coal particles finer than 3.15 mm, specifically 80%, 85%, 90%, and 95%. In each trial, 50 kg of the prepared coal sample was charged into the pilot coke oven, where it was carbonized for a period of 19 hours. After carbonization, the resulting coke was pushed out of the oven, and the pushing current was recorded. Simultaneously, the wall pressure during the carbonization process was measured for each coal sample.\u003c/p\u003e\u003cp\u003eTo maintain consistency, the moisture content of all coal samples was kept constant at 10% throughout the trials. Additionally, the bulk density of each crushed coal sample was noted prior to the experiments. This methodology allows for the evaluation of the impact of different coal qualities and particle sizes on both the wall pressure in the pilot coke oven and the pushing current required for coke removal.\u003c/p\u003e"},{"header":"Results and Discussions","content":"\u003cp\u003e\u003cstrong\u003eWall pressure with blending percent\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eThe experimental results for the three Australian coal samples—PLV, Sarji, and Peak Down—demonstrate significant findings related to wall pressure. As the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, all measured wall pressures—Sarj coal wall pressure, peak down wall pressure, and PLV wall pressure—consistently decrease as shown in Fig.\u0026nbsp;1. Specifically, Sarji wall pressure drops from 7.25 kPa to 3.89 kPa, peak down from 5.98 kPa to 3.21 kPa, and PLV from 5.82 kPa to 3.41 kPa. This indicates that increasing the fine fraction of Sarji coal leads to reduced pressure on the oven walls during coking. The finer particles improve packing density and permeability, allowing better gas flow and minimizing pressure buildup. Additionally, Sarji coal may possess lower fluidity or swelling characteristics, which further reduces the tendency to generate wall pressure. Overall, the higher percentages of fine Sarji coal improve the coking behavior by producing a more stable and less expansive coke mass, thereby reducing mechanical stress on the oven walls.\u003c/p\u003e\u003cp\u003eThe decrease in wall pressure with increasing fine Sarji coal fraction is primarily due to improved particle packing and enhanced permeability within the coal charge. Finer Sarji particles fill voids between coarser grains, resulting in a denser, more uniform matrix that facilitates easier gas escape during coking, thereby reducing pressure buildup. Additionally, Sarji coal’s lower fluidity and swelling tendencies limit lateral expansion of the plastic layer, minimizing mechanical stress on the oven walls. This combination of better packing, improved gas flow, and reduced coal expansion leads to a more stable coke structure, effectively lowering wall pressure as the fine Sarji coal content increases.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCoke quality with blending percent\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eThe quality of coke produced from the pilot coke oven was evaluated using the standard ASTM-D5341 methods, which assess both the Coke Strength After Reaction (CSR) and the Coke Reactivity Index (CRI). As shown in Figs.\u0026nbsp;2 and 3, a trend was observed where finer crushing of the coal resulted in an increase in CSR and a decrease in CRI.\u003c/p\u003e\u003cp\u003eAs the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the Coke Strength after Reaction (CSR) shows a consistent upward trend across all measurement points—Sarji, Peak Down, and PLV. Specifically, Sarji CSR increases from 62.48 to 69.39, Peak Down from 63.41 to 67.35, and PLV from 62.37 to 68.97. This indicates a significant improvement in coke strength after exposure to CO₂, which is crucial for maintaining structural integrity in the blast furnace. The rise in CSR is primarily due to the improved packing and reduced porosity that comes with a higher proportion of fine particles, resulting in a denser and more cohesive coke structure. Additionally, Sarji coal likely has favorable coking properties—such as lower fluidity and volatile matter—which contribute to forming stronger, more thermally stable coke. The simultaneous decrease in CRI and increase in CSR confirms that the coke produced becomes both less reactive and more robust as the fine Sarji coal content increases.\u003c/p\u003e\u003cp\u003eAs the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the Coke Reactivity Index (CRI) consistently decreases across all measurement points—Sarji, Peak Down, and PLV—indicating improved coke quality. Sarji CRI drops from 25.62 to 21.83, Peak Down from 25.40 to 21.60, and PLV from 26.26 to 22.39. This decline in CRI suggests that the coke becomes less reactive to CO₂, which is desirable for maintaining strength in the blast furnace. The improvement is likely due to better packing and reduced porosity from the increased fine content, as well as the intrinsic properties of Sarji coal—such as lower volatile matter and higher carbon content—which contribute to forming a denser, more thermally stable coke with lower reactivity.\u003c/p\u003e\u003cp\u003eThe observed increase in Coke Strength after Reaction (CSR) and concurrent decrease in Coke Reactivity Index (CRI) with increasing proportions of fine (-3.15 mm) Sarji coal in the blend can be attributed to improvements in the physical and chemical characteristics of the coke structure. The higher fine particle content enhances packing density and reduces porosity within the coke matrix, resulting in a denser, more cohesive structure that better resists mechanical degradation and gas attack. Additionally, Sarji coal’s favorable coking properties—such as lower fluidity, reduced volatile matter, and higher carbon content—contribute to forming coke with increased thermal stability and lower reactivity to CO₂. This combination leads to a coke product that is both stronger after reaction and less prone to degradation, which is essential for maintaining blast furnace performance. The simultaneous increase in CSR and decrease in CRI thus reflect the positive impact of fine Sarji coal on producing high-quality, robust coke.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCoke proximate analysis with blending percent\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eAs the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, both coke volatile matter (VM) and ash content show a consistent decrease across all sampling points—Sarji, Peak Down, and PLV as shown in Figs.\u0026nbsp;4 and 5. Coke VM drops significantly, with Sarji values declining from 1.61–0.92%, Peak Down from 1.65–0.94%, and PLV from 1.73–0.88%, indicating more complete devolatilization and improved coke maturity. Similarly, coke ash content decreases, with Sarji reducing from 14.18–13.15%, Peak Down from 14.89–13.45%, and PLV from 13.69–12.48%. These improvements are mainly due to the finer particle size and lower inherent VM and ash in Sarji coal, which enhance heat transfer and allow better control during carbonization. As a result, the coke produced is cleaner and more stable—favorable traits for efficient and high-quality blast furnace performance.\u003c/p\u003e\u003cp\u003eThe consistent decrease in coke volatile matter (VM) and ash content with increasing proportions of fine (-3.15 mm) Sarji coal in the blend can be attributed to the combined effects of particle size and coal composition on the carbonization process. The finer Sarji coal particles improve heat transfer efficiency within the coal charge, promoting more uniform and complete devolatilization, which reduces residual volatile matter in the resulting coke. Additionally, Sarji coal inherently possesses lower VM and ash content compared to the other coals, contributing to a cleaner coke product. The reduced ash content is also a result of the dilution effect as the finer Sarji coal replaces higher ash components in the blend. Together, these factors enhance coke maturity and stability by producing a denser, lower-impurity coke structure, which is advantageous for blast furnace operations by improving coke reactivity and mechanical strength.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCoke porosity with blending percent\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eAs the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, the porosity of the resulting coke decreases steadily across all sampling points—Sarji, Peak Down, and PLV as shown in Fig.\u0026nbsp;6. Sarji porosity drops from 52–44%, Peak Down from 52.35–44.47%, and PLV from 52.15–44.25%. This reduction in porosity indicates a denser, more compact coke structure, which is beneficial for improving coke strength and reducing reactivity. The decline in porosity is primarily due to the finer particle size of Sarji coal, which allows for better packing and fewer voids during the coking process. Additionally, Sarji coal likely possesses coking properties that favor the formation of a more consolidated coke matrix. Lower porosity enhances the mechanical strength and stability of coke in the blast furnace, making it more resistant to degradation under load and during gas reactions.\u003c/p\u003e\u003cp\u003eThe steady decrease in coke porosity with increasing proportions of fine (-3.15 mm) Sarji coal in the blend is primarily attributed to enhanced particle packing and improved matrix consolidation during coking. The finer Sarji particles fill interstitial voids more effectively, resulting in a denser and more compact coke structure with fewer pores. This improved packing reduces the overall porosity by minimizing the formation of large void spaces within the coke. Additionally, the intrinsic coking properties of Sarji coal, such as its lower fluidity and favorable plasticity range, contribute to the development of a more consolidated and stable coke matrix. Lower porosity enhances the mechanical strength and thermal stability of the coke, making it more resistant to physical degradation and chemical reactions in the blast furnace environment. This structural densification ultimately leads to improved coke performance, supporting more efficient and reliable blast furnace operations.\u003c/p\u003e\u003cp\u003e\u003cb\u003eCoke pushing power consumption with blending percent\u003c/b\u003e:\u003c/p\u003e\u003cp\u003eAs the proportion of (-3.15 mm) Sarji coal in the blend increases from 80–95%, power consumption during the coking process shows some fluctuation across different sampling points—Sarji, Peak Down, and PLV. Sarji power consumption increases from 230.5 kW to 226.6 kW, Peak Down shows a more significant increase from 259.2 kW to 263.3 kW, and PLV fluctuates between 224.6 kW and 225.9 kW. Overall, there is a slight increase in power consumption for Peak Down, while Sarji and PLV show stable or slightly reduced power usage. The variation in power consumption is influenced by the blend's impact on the coking process, where higher percentages of fine Sarji coal likely improve the packing and thermal conductivity, which can sometimes reduce the energy required for heating. However, the differences observed, particularly in Peak Down, may result from variations in the specific combustion characteristics of the coal and the required adjustments to maintain consistent heating. Fine Sarji coal may also lead to more efficient heat transfer, requiring less power in some areas while slightly increasing it in others due to its impact on the coking dynamics.\u003c/p\u003e\u003cp\u003eThe observed fluctuations in power consumption during coking with increasing proportions of fine (-3.15 mm) Sarji coal are influenced by the interplay between improved packing, thermal conductivity, and the intrinsic combustion characteristics of the coal blend. The finer Sarji particles enhance packing density, which can improve thermal contact between particles and promote more efficient heat transfer throughout the coal charge, potentially reducing the overall energy required for heating. However, variations in coal composition, particularly with Peak Down coal, may affect combustion behavior and the thermal profile within the oven, necessitating adjustments in power input to maintain consistent temperature control. Differences in volatile matter content, fixed carbon, and ash can alter the combustion kinetics, leading to localized increases or decreases in power demand. Consequently, while fine Sarji coal generally supports more efficient heat transfer and can lower power consumption, these benefits may be offset by the specific thermal and combustion dynamics of the blend components, resulting in the observed fluctuations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe present study systematically evaluated the impact of selective fine crushing on high Mean Maximum Reflectance (MMR) Australian coals\u0026mdash;Sarji, Peak Down, and PLV\u0026mdash;for coke-making applications. The experimental investigations, carried out in a pilot-scale coke oven, revealed that increasing the proportion of coal particles finer than 3.15 mm notably improves coking behavior, particularly in reducing wall pressure and enhancing coke quality metrics.\u003c/p\u003e\u003cp\u003eA progressive increase in the fine fraction of Sarji coal from 80\u0026ndash;95% led to a consistent decline in wall pressure, indicating reduced mechanical stress on coke oven walls\u0026mdash;a critical factor for the safe and efficient utilization of high-pressure coals. Correspondingly, the Coke Strength after Reaction (CSR) improved, and the Coke Reactivity Index (CRI) declined, signifying the production of stronger and less reactive coke suitable for high-performance blast furnace operations.\u003c/p\u003e\u003cp\u003eThe finer coal blends also contributed to lower coke volatile matter and ash content, as well as reduced porosity, yielding a denser and more thermally stable coke structure. These enhancements can be attributed to improved particle packing, permeability, and heat transfer efficiency during carbonization. Furthermore, power consumption during coke pushing remained stable or slightly reduced, indicating energy-efficient performance under optimized crushing conditions.\u003c/p\u003e\u003cp\u003eOverall, the results affirm that selective fine crushing of high MMR coals, particularly Sarji, is an effective strategy to mitigate coking pressure-related challenges while simultaneously improving coke quality. This approach facilitates the broader utilization of high-reflectance, high-swelling coals in metallurgical coke blends, supporting more flexible and efficient coke oven operation without compromising structural integrity or coke performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAuthor contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKarthik G conceived and designed the experimental plan. Vikas u conducted the experiments, and Mrunmaya KP analyzed the results and contributed to data analysis and interpretation. Karthik G wrote the manuscript. All authors reviewed and approved the final version of the manuscript.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSeiji NOMURA,\u003csup\u003e1) \u003c/sup\u003eTakashi ARIMA,\u003csup\u003e1)\u003c/sup\u003e Atsushi DOBASHI\u003csup\u003e2) \u003c/sup\u003eand Kazuhide DOI\u003csup\u003e3)\u003c/sup\u003e, Nippon Steel Corporation, Environment \u0026amp; Process Technology Center, 20-1, Shintomi, Futtsu, Chiba, 293-8511 Japan.\u003c/li\u003e\n\u003cli\u003eS. Nomura and T. Arima: Fuel, 80 (2001), 1307\u003c/li\u003e\n\u003cli\u003eNakashima, Y. et al.: 2nd Int. Cokemaking Congr. London, UK, 1992, p.518\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eJ. S. Atr. Inst. Min. Metal/., vo!. 91, no. 2. Feb. 1991. pp. ,53-61.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eB. K. Sahooa, *, B. Ghosha, **, P. K. Jhaa, ***, P. K. Pankaja, ****, S. K. Kushwahaa, *****, B. Chakrabortya, ******, K. K. Manjhia, *******, and N. Pradhana, ********, DOI: 10.3103/S1068364X21080068\u003c/li\u003e\n\u003cli\u003eRamon Alvarez, Jose J. Pis, and Maria A. Diez Instituto National del Carbon INCAR, C.S.I.C, Apartado 73, Oviedo 33080, Spain Anna Marzec* and Sylwia Czajkowska Institute of Coal Chemistry, Polish Academy of Sciences, Sowinskiego 5, 44-102 Gliwice, Poland. \u003cem\u003eEnergy \u0026amp; Fuels 1997, 11, 978-981\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eCoking Pressure Seminar. Cokemaking Int. 1992, 4, 1-40. \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMarzec, A.; Alvarez, R.; Casal, D. M.; Schulten, H.-R. Energy Fuels 1995, 9, 834-840.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eBarriocanal, C.; Patrick, J. W.; Walker, A.; Walker, A. R. The Identification of Dangerously Coking Coals. In Coal Science; Pajares, J. A., Tascon, J. M. D., Eds; Elsevier: Amsterdam, 1995; Vol. 1, pp 989-992.\u003c/li\u003e\n\u003cli\u003eKoch, A.; Gruber, R.; Cagniant, D.; Krzton, A.; Duchene, J. M. Fuel Process. Technol. 1995, 45, 135-153.\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eSteyls, D. Cokemaking Int. 1992, 4, 31-33\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eNaoto TSUBOUCHI,\u003csup\u003e1) * \u003c/sup\u003eRyo NAGANUMA,\u003csup\u003e1) \u003c/sup\u003eYuuki MOCHIZUKI,\u003csup\u003e1) \u003c/sup\u003eHideyuki HAYASHIZAKI,\u003csup\u003e2) \u003c/sup\u003eTakahiro SHISHIDO\u003csup\u003e3) \u003c/sup\u003eand Atul SHARMA\u003csup\u003e4)\u003c/sup\u003e. (2019), No. 8 \u0026copy; \u003cem\u003e2019 ISIJ 1396 ISIJ International, Vol. 59 (2019), No. 8, pp. 1396\u0026ndash;1403 (2019)\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eN. Okuyama, T. Shigehisa, Y. Nishibata, K. Matsudaira and M. Nishimura: Tetsu-to-Hagan\u0026eacute;, 92 (2006), 213 (in Japanese).\u003c/li\u003e\n\u003cli\u003eP. R. Solomon, M. A. Serio, G. V. Despande and E. Kroo: Energy Fuel., 4 (1990), 42.\u003c/li\u003e\n\u003cli\u003eF. Goodarzi and D. G. Murchison: Fuel, 51 (1972), 322.\u003c/li\u003e\n\u003cli\u003eG. D. Cody, J. W. Larsen and M. Siskin: Energy Fuel., 2 (1988), 340. 5) L. M. Lucht and N. A. Peppas: Fuel, 66 (1987), 803.\u003c/li\u003e\n\u003c/ol\u003e "},{"header":"Table 1","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"JSW Group (India)","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Selective fine crushing, wall pressure, High MMR, Coke quality","lastPublishedDoi":"10.21203/rs.3.rs-7248294/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7248294/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSelective fine crushing of high Mean Maximum Reflectance (MMR) Australian coking coals\u0026mdash;Sarji, Peak Down, and PLV\u0026mdash;was studied to enhance coke quality and reduce wall pressure during coking. Each coal was crushed to varying degrees (-3.15 mm at 80%, 85%, 90%, and 95%) and carbonized in a pilot-scale coke oven. The resulting coke was evaluated for wall pressure, CSR, CRI, porosity, volatile matter, ash content, and power consumption. Results showed that increasing fine coal content, especially in Sarji coal, significantly reduced wall pressure (from 7.25 to 3.89 kPa) and porosity, while improving CSR (from 62.48 to 69.39) and reducing CRI (from 25.62 to 21.83). These benefits were linked to better particle packing, gas permeability, and reduced swelling. Additionally, coke from finer blends exhibited lower volatile matter and ash, enhancing thermal stability. Power consumption remained stable, highlighting process efficiency. Selective fine crushing proves to be an effective method for producing high-quality coke from high MMR coals.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e","manuscriptTitle":"Evaluation of High Mean of Maximum Reflectance(MMR) coals for coke making through selective crushing","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-01 12:15:49","doi":"10.21203/rs.3.rs-7248294/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"33622f11-a4af-4be2-9c24-51f98be9b2f3","owner":[],"postedDate":"August 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":52339322,"name":"Materials Engineering"}],"tags":[],"updatedAt":"2025-08-01T12:15:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-01 12:15:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7248294","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7248294","identity":"rs-7248294","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}