Pub Date : 2024-11-21DOI: 10.1016/j.powtec.2024.120457
Shaomin Liang , Y.T. Feng , Zhihua Wang
The fragmentation behavior of particle materials is widely observed in natural environments, engineering applications, and other fields. It is an important factor contributing to natural disasters and engineering accidents. This paper aims to provide a selective overview of research methods for studying particle fragmentation behavior. The review primarily focuses on numerical methods for investigating particle fragmentation and key problems of interest in this field. Firstly, it classifies and summarizes the numerical methods based on the discrete element method, the coupling of discrete element and finite element method, the finite element method, and the peridynamics theory. It outlines the proposal, implementation process, development history, major applications, and existing issues associated with each method, suggesting possible solutions where applicable. Secondly, it discusses key issues in particle fragmentation research, including fragmentation mechanisms, fragmentation criteria, major influencing factors, size distribution, and energy problems. Finally, the paper concludes with an outlook on future research efforts in the field of particle fragmentation.
{"title":"Numerical methods and key issues for the study of particle material fragmentation behavior-A review","authors":"Shaomin Liang , Y.T. Feng , Zhihua Wang","doi":"10.1016/j.powtec.2024.120457","DOIUrl":"10.1016/j.powtec.2024.120457","url":null,"abstract":"<div><div>The fragmentation behavior of particle materials is widely observed in natural environments, engineering applications, and other fields. It is an important factor contributing to natural disasters and engineering accidents. This paper aims to provide a selective overview of research methods for studying particle fragmentation behavior. The review primarily focuses on numerical methods for investigating particle fragmentation and key problems of interest in this field. Firstly, it classifies and summarizes the numerical methods based on the discrete element method, the coupling of discrete element and finite element method, the finite element method, and the peridynamics theory. It outlines the proposal, implementation process, development history, major applications, and existing issues associated with each method, suggesting possible solutions where applicable. Secondly, it discusses key issues in particle fragmentation research, including fragmentation mechanisms, fragmentation criteria, major influencing factors, size distribution, and energy problems. Finally, the paper concludes with an outlook on future research efforts in the field of particle fragmentation.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120457"},"PeriodicalIF":4.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.powtec.2024.120473
Shiwei Wang , Mohana Rao Kadagala , Luis Vinnett , Naresh Kumar Sharma , Guomin Wei
The effectiveness of flotation for decarbonizing fine slag from coal gasification depends on the selection of appropriate collectors or surfactants. This study explored the synergistic effect of kerosene combined with cationic surfactants, including dodecyl trimethylammonium chloride, dodecylamine, and dodecylamine hydrochloride, on recovering residual carbonaceous material from coal gasification fine slag, using both MD and experimental simulations. The Scanning electron microscopy and X-ray spectroscopy revealed that the water molecules and oxygen-rich silicon glass beads dominated the slag surface, while the XPS analysis demonstrated that the functional groups containing oxygen on the residual carbon surface promote hydrogen bonding with water molecules in the flotation solution. The results suggested that the highest yield, along with optimal Loss on Ignition (LOI) and combustible recovery, was achieved at the 10−5 mol/L surfactant concentration. The MD simulations demonstrated that dodecylamine had the highest diffusion coefficient and adsorption capacity, explaining its superior interaction with residual carbon surfaces and its effectiveness in the decarbonization process. This approach contributed to the valorization and reuse of carbon generated by the waste of coal gasification fine slag.
利用浮选法对煤气化产生的细渣进行脱碳的效果取决于选择适当的捕收剂或表面活性剂。本研究利用 MD 和实验模拟，探讨了煤油与阳离子表面活性剂（包括十二烷基三甲基氯化铵、十二烷基胺和十二烷基胺盐酸盐）相结合对回收煤气化细渣中残余碳质材料的协同效应。扫描电子显微镜和 X 射线光谱分析发现，水分子和富氧硅玻璃珠在炉渣表面占主导地位，而 XPS 分析表明，残炭表面的含氧官能团促进了与浮选溶液中水分子的氢键结合。结果表明，在表面活性剂浓度为 10-5 摩尔/升时，产率最高，点火损失（LOI）和可燃物回收率也最佳。MD 模拟表明，十二胺具有最高的扩散系数和吸附能力，这说明了它与残炭表面的卓越相互作用及其在脱碳过程中的有效性。这种方法有助于煤气化细渣废物产生的碳的价值化和再利用。
{"title":"Investigation on a novel mixed collector for carbon recovery from coal gasification fine slag: Experimental insight and macro molecular simulations","authors":"Shiwei Wang , Mohana Rao Kadagala , Luis Vinnett , Naresh Kumar Sharma , Guomin Wei","doi":"10.1016/j.powtec.2024.120473","DOIUrl":"10.1016/j.powtec.2024.120473","url":null,"abstract":"<div><div>The effectiveness of flotation for decarbonizing fine slag from coal gasification depends on the selection of appropriate collectors or surfactants. This study explored the synergistic effect of kerosene combined with cationic surfactants, including dodecyl trimethylammonium chloride, dodecylamine, and dodecylamine hydrochloride, on recovering residual carbonaceous material from coal gasification fine slag, using both MD and experimental simulations. The Scanning electron microscopy and X-ray spectroscopy revealed that the water molecules and oxygen-rich silicon glass beads dominated the slag surface, while the XPS analysis demonstrated that the functional groups containing oxygen on the residual carbon surface promote hydrogen bonding with water molecules in the flotation solution. The results suggested that the highest yield, along with optimal Loss on Ignition (LOI) and combustible recovery, was achieved at the 10<sup>−5</sup> mol/L surfactant concentration. The MD simulations demonstrated that dodecylamine had the highest diffusion coefficient and adsorption capacity, explaining its superior interaction with residual carbon surfaces and its effectiveness in the decarbonization process. This approach contributed to the valorization and reuse of carbon generated by the waste of coal gasification fine slag.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120473"},"PeriodicalIF":4.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.powtec.2024.120469
Hayfa Boussoffara , Cendrine Gatumel , Blandine Malécot , Maxime Viau , Henri Berthiaux
This work adopts an in-system rheological approach to analyse powder flow behaviour in dense flows under mechanical agitation. For this purpose, an empirical law has been developed to assess powder rheology within a laboratory mixing setup, focusing on interactions between the paddles and the powder bed in dense flow. This model, is an empirical law, based on the μ(I)-rheology-like framework derived from dimensional analysis and shear band visualization. It reveals good predictive capabilities for powders of similar particle shapes but different sizes across various filling ratios. This approach addresses challenges in measuring complex powder parameters, such as the effective friction coefficient , establishing a practical and easily applicable model that facilitates the scaling up of mixing processes and allows for better anticipation of forces exerted on the paddles. Comparisons with Hatano's equation showed a good fit with the rheological framework, particularly for deep powder beds. Better evaluation of the shear band width and reconsideration of normal stress assumptions may be the way forward to improve the accuracy of this μ(I)-rheology.
{"title":"A rheological law to describe powder agitation in a lab-scale paddle mixer: Shear band observation and dimensional analysis","authors":"Hayfa Boussoffara , Cendrine Gatumel , Blandine Malécot , Maxime Viau , Henri Berthiaux","doi":"10.1016/j.powtec.2024.120469","DOIUrl":"10.1016/j.powtec.2024.120469","url":null,"abstract":"<div><div>This work adopts an in-system rheological approach to analyse powder flow behaviour in dense flows under mechanical agitation. For this purpose, an empirical law has been developed to assess powder rheology within a laboratory mixing setup, focusing on interactions between the paddles and the powder bed in dense flow. This model, is <em>an empirical</em> law, based on the μ(I)-rheology-like framework derived from dimensional analysis and shear band visualization. It reveals good predictive capabilities for powders of similar particle shapes but different sizes across various filling ratios. This approach addresses challenges in measuring complex powder parameters, such as the effective friction coefficient <span><math><msub><mi>μ</mi><mi>eff</mi></msub></math></span>, establishing a practical and easily applicable model that facilitates the scaling up of mixing processes and allows for better anticipation of forces exerted on the paddles. Comparisons with Hatano's equation showed a good fit with the rheological framework, particularly for deep powder beds. Better evaluation of the shear band width and reconsideration of normal stress assumptions may be the way forward to improve the accuracy of this μ(I)-rheology.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120469"},"PeriodicalIF":4.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-21DOI: 10.1016/j.powtec.2024.120467
Damla Serper , Kevin J. Hanley , Pekka Oinas
The discrete element method (DEM) offers enormous potential to gain a better understanding of cake formation in centrifugal filtration. However, the necessity to represent the highly porous filter mesh in these simulations incurs a significant computational cost. We propose replacing the porous mesh boundary that is conventionally used with a ‘switchable contact model’ (SCM) in which the contact model between a particle and a continuous cylindrical shell is selectively enabled or disabled depending on the particle's location at the periphery of the centrifuge basket. SCM is disabled whenever a particle is deemed to be in contact with a pore location, thus allowing its egress from the basket. There was a ∼ 36 % reduction in computation time compared to the conventional mesh-based representation of a bounding filter mesh, with similar particle retention and bulk cake formation behavior. This concept could in principle be applied to model any repetitive porous structure in DEM.
{"title":"Computationally efficient DEM simulation of a basket-type centrifugal filter using a novel switchable contact model","authors":"Damla Serper , Kevin J. Hanley , Pekka Oinas","doi":"10.1016/j.powtec.2024.120467","DOIUrl":"10.1016/j.powtec.2024.120467","url":null,"abstract":"<div><div>The discrete element method (DEM) offers enormous potential to gain a better understanding of cake formation in centrifugal filtration. However, the necessity to represent the highly porous filter mesh in these simulations incurs a significant computational cost. We propose replacing the porous mesh boundary that is conventionally used with a ‘switchable contact model’ (SCM) in which the contact model between a particle and a continuous cylindrical shell is selectively enabled or disabled depending on the particle's location at the periphery of the centrifuge basket. SCM is disabled whenever a particle is deemed to be in contact with a pore location, thus allowing its egress from the basket. There was a ∼ 36 % reduction in computation time compared to the conventional mesh-based representation of a bounding filter mesh, with similar particle retention and bulk cake formation behavior. This concept could in principle be applied to model any repetitive porous structure in DEM.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"452 ","pages":"Article 120467"},"PeriodicalIF":4.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.powtec.2024.120472
Jie Wang , Hongyue Dong , Haifeng Xu , Fengsong Fan , Hebin Xu , Haoyang Wu , Yunpu Qin , Zihao Li , Huihuang Song , Qiang Chen , Baorui Jia , Deyin Zhang , Mingli Qin , Xuanhui Qu
Component shape and pore structure are crucial to the application of porous tungsten, and are significantly affected by the powder size. In this work, porous tungsten with complex shape and controllable pore structure were prepared by the combination of jet milling and injection molding, and the effects of powder size (5, 2 and 0.6 μm) on jet milling, injection molding and pore structure were systematically investigated. The results showed that in contrast to the complete dispersion observed with micron-sized powders, ultrafine powder still had residual agglomerations after jet milling, which further led to a relatively low critical solid loading (47 %) and moldability index (=1.85) during injection molding. For porous pore structure, finer powder was more conducive to obtain smaller pore size and more complex pore structure. At the same porosity (27 %), with the decrease of powder size, the pore size decreased from 1028 nm to 552 nm and 350 nm, and the corresponding fractal dimension increased from 2.19 to 2.84 and 2.99. In contrast, the compressive strength increased as the powder size decreased, rising from 488 MPa to 640 MPa and 883 MPa. The establishment of the relationship between powder size, moldability, and pore characteristics provides valuable insights for the raw powder selection and pore structure control, which is of great significance for the precise preparation and application promotion of porous tungsten.
{"title":"Effect of powder size on the moldability and pore characteristics of porous tungsten by injection molding","authors":"Jie Wang , Hongyue Dong , Haifeng Xu , Fengsong Fan , Hebin Xu , Haoyang Wu , Yunpu Qin , Zihao Li , Huihuang Song , Qiang Chen , Baorui Jia , Deyin Zhang , Mingli Qin , Xuanhui Qu","doi":"10.1016/j.powtec.2024.120472","DOIUrl":"10.1016/j.powtec.2024.120472","url":null,"abstract":"<div><div>Component shape and pore structure are crucial to the application of porous tungsten, and are significantly affected by the powder size. In this work, porous tungsten with complex shape and controllable pore structure were prepared by the combination of jet milling and injection molding, and the effects of powder size (5, 2 and 0.6 μm) on jet milling, injection molding and pore structure were systematically investigated. The results showed that in contrast to the complete dispersion observed with micron-sized powders, ultrafine powder still had residual agglomerations after jet milling, which further led to a relatively low critical solid loading (47 %) and moldability index (<span><math><msub><mi>α</mi><mi>stv</mi></msub></math></span>=1.85) during injection molding. For porous pore structure, finer powder was more conducive to obtain smaller pore size and more complex pore structure. At the same porosity (27 %), with the decrease of powder size, the pore size decreased from 1028 nm to 552 nm and 350 nm, and the corresponding fractal dimension increased from 2.19 to 2.84 and 2.99. In contrast, the compressive strength increased as the powder size decreased, rising from 488 MPa to 640 MPa and 883 MPa. The establishment of the relationship between powder size, moldability, and pore characteristics provides valuable insights for the raw powder selection and pore structure control, which is of great significance for the precise preparation and application promotion of porous tungsten.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"452 ","pages":"Article 120472"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.powtec.2024.120451
Marcella Horst , Franziska Beverborg , Lukas Bahlmann , Svenja Schreiber , Julius Gerk , Peter Michalowski , Arno Kwade
This study investigates the significant impact of different active material particle morphologies – platelet-like graphite, spherical highly porous LFP, and spherical NCM – on PTFE fibrillation during mixing and calendering steps of a dry coating process. Graphite's platelet-like structure slows PTFE fibrillation compared to LFP's structure, which exhibits prolonged PTFE fibrillation due to its fine particle content. NCM, with higher density and compaction speed, promotes faster PTFE fibrillation during mixing. The hierarchical morphology of the fibrils determines the powder blend properties. Consequently, powder behaviour in the calender gap was characterised using uniaxial compression and ring shear cell tests. Uniaxial compression tests revealed that NCM-based powder requires higher compression stress. Under consistent calendering conditions, it forms thicker dry-coated films compared to the graphite-based powder, which requires lower compression stress and forms thinner films. These findings are supported by ring shear cell tests, which showed lower wall friction for graphite-based powder and a higher wall friction angle for NCM-based powder. Additionally, the porosity of the free-standing films can be predicted using uniaxial compression tests. These results highlight the need for tailored mixing and calendering processes for each active material to optimize electrode properties in dry coating processes for lithium-ion batteries.
{"title":"Effect of active material morphology on PTFE-fibrillation, powder characteristics and electrode properties in dry electrode coating processes","authors":"Marcella Horst , Franziska Beverborg , Lukas Bahlmann , Svenja Schreiber , Julius Gerk , Peter Michalowski , Arno Kwade","doi":"10.1016/j.powtec.2024.120451","DOIUrl":"10.1016/j.powtec.2024.120451","url":null,"abstract":"<div><div>This study investigates the significant impact of different active material particle morphologies – platelet-like graphite, spherical highly porous LFP, and spherical NCM – on PTFE fibrillation during mixing and calendering steps of a dry coating process. Graphite's platelet-like structure slows PTFE fibrillation compared to LFP's structure, which exhibits prolonged PTFE fibrillation due to its fine particle content. NCM, with higher density and compaction speed, promotes faster PTFE fibrillation during mixing. The hierarchical morphology of the fibrils determines the powder blend properties. Consequently, powder behaviour in the calender gap was characterised using uniaxial compression and ring shear cell tests. Uniaxial compression tests revealed that NCM-based powder requires higher compression stress. Under consistent calendering conditions, it forms thicker dry-coated films compared to the graphite-based powder, which requires lower compression stress and forms thinner films. These findings are supported by ring shear cell tests, which showed lower wall friction for graphite-based powder and a higher wall friction angle for NCM-based powder. Additionally, the porosity of the free-standing films can be predicted using uniaxial compression tests. These results highlight the need for tailored mixing and calendering processes for each active material to optimize electrode properties in dry coating processes for lithium-ion batteries.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120451"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigated the effects of different Cr₂O₃ contents on the mechanical and electrical properties of Cu-based composites using spray drying technology. The influence of varying Cr2O3 concentrations on the powder morphology was systematically investigated. Cold pressing and sintering were utilized to fabricate composite blocks to examine the microstructures, mechanical properties, and electrical conductivity with different Cr2O3 content. Our findings reveal that the inclusion of Cr2O3 led to a reduction in conductivity, while significantly improving the hardness. Notably, an optimal Cr2O3 concentration of 0.8 wt% gained a remarkable increase in yield strength to 215 MPa and ultimate tensile strength to 255.96 MPa, marking improvements of 104.76 % and 114.91 %, respectively, over composites prepared with pure Cu powders. The balance achieved between mechanical robustness and conductivity suggests a promising potential for these composites in electrical applications.
{"title":"Enhanced mechanical and electrical properties of Cu matrix composites with ultrafine Cr2O3 particles by spray drying","authors":"Longshan Xu, Xiaoshuai Wang, Yurong Wu, Siqing Song, Yanling Hu, Yuhui Zhang","doi":"10.1016/j.powtec.2024.120466","DOIUrl":"10.1016/j.powtec.2024.120466","url":null,"abstract":"<div><div>This study investigated the effects of different Cr₂O₃ contents on the mechanical and electrical properties of Cu-based composites using spray drying technology. The influence of varying Cr<sub>2</sub>O<sub>3</sub> concentrations on the powder morphology was systematically investigated. Cold pressing and sintering were utilized to fabricate composite blocks to examine the microstructures, mechanical properties, and electrical conductivity with different Cr<sub>2</sub>O<sub>3</sub> content. Our findings reveal that the inclusion of Cr<sub>2</sub>O<sub>3</sub> led to a reduction in conductivity, while significantly improving the hardness. Notably, an optimal Cr<sub>2</sub>O<sub>3</sub> concentration of 0.8 wt% gained a remarkable increase in yield strength to 215 MPa and ultimate tensile strength to 255.96 MPa, marking improvements of 104.76 % and 114.91 %, respectively, over composites prepared with pure Cu powders. The balance achieved between mechanical robustness and conductivity suggests a promising potential for these composites in electrical applications.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120466"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.powtec.2024.120463
Metin Uçurum , Akın Özdemir , Çağatay Teke
Fly ash (FA) is the fine-grained waste product obtained by burning coal after being ground to specific sizes in thermal power plants, carried with flue gases, and kept in cyclones or electro-filters. Like every industrial waste, the possibilities of utilizing FA have been investigated, and it can be utilized as an additive in cement and concrete. Despite this, industrial waste, which increases daily in the world, brings many problems, especially environmental problems. For this reason, alternative usage areas of the waste in question are constantly being investigated. In this paper, FA containing approximately 50 % CaO from Afşin-Elbistan, Turkiye was processed with stearic acid in a planetary mill to be used as a filling material in industrial products, and it has a grain size of 68.10 μm on a d50 basis, a specific surface area (SSA) of 176.40 m2/g and a contact angle of 13.89. An optimization and characterization study was conducted to make the hydrophilic surface structure hydrophobic by mechanochemical surface modification. Also, surface modification parameters, such as operational speed (rpm), ball filling ratio (%), FA filling ratio (%), pulp density, stearic acid dosage (% of FA), and modification time (min.) were optimized with the D-optimal experimental design. Based on the optimum surface modification parameters, a coated fly ash (CFA) product was obtained with an active ratio of 99.70 %, a contact angle of 95.06o, a medium size (d50) size of 10.60 μm, and an SSA of 926.90 m2/g.
{"title":"Optimization of surface modification parameters of fly ash with high calcium oxide (CaO) content to use as a filling material","authors":"Metin Uçurum , Akın Özdemir , Çağatay Teke","doi":"10.1016/j.powtec.2024.120463","DOIUrl":"10.1016/j.powtec.2024.120463","url":null,"abstract":"<div><div>Fly ash (FA) is the fine-grained waste product obtained by burning coal after being ground to specific sizes in thermal power plants, carried with flue gases, and kept in cyclones or electro-filters. Like every industrial waste, the possibilities of utilizing FA have been investigated, and it can be utilized as an additive in cement and concrete. Despite this, industrial waste, which increases daily in the world, brings many problems, especially environmental problems. For this reason, alternative usage areas of the waste in question are constantly being investigated. In this paper, FA containing approximately 50 % CaO from Afşin-Elbistan, Turkiye was processed with stearic acid in a planetary mill to be used as a filling material in industrial products, and it has a grain size of 68.10 μm on a <em>d</em><sub>50</sub> basis, a specific surface area (SSA) of 176.40 m<sup>2</sup>/g and a contact angle of 13.89. An optimization and characterization study was conducted to make the hydrophilic surface structure hydrophobic by mechanochemical surface modification. Also, surface modification parameters, such as operational speed (rpm), ball filling ratio (%), FA filling ratio (%), pulp density, stearic acid dosage (% of FA), and modification time (min.) were optimized with the <em>D</em>-optimal experimental design. Based on the optimum surface modification parameters, a coated fly ash (CFA) product was obtained with an active ratio of 99.70 %, a contact angle of 95.06<sup>o</sup>, a medium size (<em>d</em><sub>50</sub>) size of 10.60 μm, and an SSA of 926.90 m<sup>2</sup>/g.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120463"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study focused on representing the three-dimensional (3D) structure of individual aggregates based on their two-dimensional (2D) images. This starts with the determination of 2D box-counting fractal dimension (), uses a previously derived empirical correlation to obtain 3D power law fractal dimension (), and then builds the aggregate on the basis of by an existing algorithm. Validation of this procedure can be done in forward or backward manner. Forward validation requires the existence of tomographic measurements of . It has been conducted on aggregates of large primary particles produced to this purpose in a spray fluidized bed and analyzed by X-ray micro-computed tomography (μ-CT). For the same agglomerates backward validation has also been exercised, starting the representation from 2D projections of the 3D objects and repeating the same procedure on the represented aggregates to see, how accurately the fractal dimensions of the original objects are reproduced. When the primary particles are too small in size to be resolved by X-ray μ-CT, only 2D imaging data by electron microscopy are usually available. Such images have been taken from literature for aggregates composed of submicron particles or nanoparticles and used for aggregate representation in 3D. Subsequently, backward validation of the procedure has been conducted. Both forward validation and backward validation results indicate a high level of consistency between the fractal characteristics and morphological structures of the represented aggregates and those of the original ones. Additionally, this study shows that the method is effective for aggregates of bidisperse and polydisperse particles.
{"title":"Representation of aggregates from their two-dimensional images for primary particles of different sizes","authors":"Rui Wang, Aisel Ajalova, Subash Reddy Kolan, Torsten Hoffmann, Kaicheng Chen, Evangelos Tsotsas","doi":"10.1016/j.powtec.2024.120465","DOIUrl":"10.1016/j.powtec.2024.120465","url":null,"abstract":"<div><div>This study focused on representing the three-dimensional (3D) structure of individual aggregates based on their two-dimensional (2D) images. This starts with the determination of 2D box-counting fractal dimension (<span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>BC</mi><mo>,</mo><mn>2</mn><mi>D</mi></mrow></msub></math></span>), uses a previously derived empirical correlation to obtain 3D power law fractal dimension (<span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span>), and then builds the aggregate on the basis of <span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span> by an existing algorithm. Validation of this procedure can be done in forward or backward manner. Forward validation requires the existence of tomographic measurements of <span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span>. It has been conducted on aggregates of large primary particles produced to this purpose in a spray fluidized bed and analyzed by X-ray micro-computed tomography (μ-CT). For the same agglomerates backward validation has also been exercised, starting the representation from 2D projections of the 3D objects and repeating the same procedure on the represented aggregates to see, how accurately the fractal dimensions of the original objects are reproduced. When the primary particles are too small in size to be resolved by X-ray μ-CT, only 2D imaging data by electron microscopy are usually available. Such images have been taken from literature for aggregates composed of submicron particles or nanoparticles and used for aggregate representation in 3D. Subsequently, backward validation of the procedure has been conducted. Both forward validation and backward validation results indicate a high level of consistency between the fractal characteristics and morphological structures of the represented aggregates and those of the original ones. Additionally, this study shows that the method is effective for aggregates of bidisperse and polydisperse particles.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120465"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.powtec.2024.120434
Dongdong Liu, Binjie Tan, Hongdong Yin, Zeyu Wu, Xiang Luo
Droplet impacting on a sufficiently heated powder bed resembles those on a superheated solid surface, as the surface deformation is mediated by the spontaneously generated vapor flow from the bottom surface of the droplet. This emerged impacting behavior is denoted as vapor-mediated impact to differentiate from the wetting impact, which involves the wetting and absorption of the particles due to capillarity. We systematically vary the impacting velocity and the temperature of the powder bed to characterize the impacting dynamics for these two behaviors. For the vapor-mediated impact, the contact time and the maximum spreading diameter are found to have the same scaling laws derived for impact on the superheated surface. We construct a phase diagram of the impacting behaviors based on experimental observation, and propose a simplified model to predict the transition between these two behaviors. The predicted values match well with the experimental results, suggesting the proposed model captures the physical mechanism of the vapor-mediated impact.
{"title":"Vapor-mediated impact of droplet on superheated powder bed","authors":"Dongdong Liu, Binjie Tan, Hongdong Yin, Zeyu Wu, Xiang Luo","doi":"10.1016/j.powtec.2024.120434","DOIUrl":"10.1016/j.powtec.2024.120434","url":null,"abstract":"<div><div>Droplet impacting on a sufficiently heated powder bed resembles those on a superheated solid surface, as the surface deformation is mediated by the spontaneously generated vapor flow from the bottom surface of the droplet. This emerged impacting behavior is denoted as vapor-mediated impact to differentiate from the wetting impact, which involves the wetting and absorption of the particles due to capillarity. We systematically vary the impacting velocity and the temperature of the powder bed to characterize the impacting dynamics for these two behaviors. For the vapor-mediated impact, the contact time and the maximum spreading diameter are found to have the same scaling laws derived for impact on the superheated surface. We construct a phase diagram of the impacting behaviors based on experimental observation, and propose a simplified model to predict the transition between these two behaviors. The predicted values match well with the experimental results, suggesting the proposed model captures the physical mechanism of the vapor-mediated impact.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120434"},"PeriodicalIF":4.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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