Powder Technology最新文献_第2页

Investigation of crack self-healing behaviour and its impact on strength and permeability recovery in cemented paste tailings

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-28 DOI: 10.1016/j.powtec.2025.120834

Weizhou Quan, Mamadou Fall

Cemented paste backfill (an engineered mixture of tailings, binder, and water), as one of the sustainable technological innovations for mining waste management, is used extensively around the world as a cementitious construction material in underground mines. The induced cracks within the CPB material tend to severely weaken the integrity and mechanical strength of the CPB structures as well as increase their permeability properties, undermining their safety, serviceability, durability, and environmental performance. However, no studies have been conducted to investigate the autogenous self-healing capability and behaviour of CPB. Therefore, this paper presents the results of an experimental study on the autogenous healing behaviour in CPB material to understand the self-healing mechanism and evaluate the self-healing efficiency through the recovery of mechanical and permeation properties. To this end, the CPB specimens were pre-damaged at different initial curing periods (i.e., 3, 7, and 28 days) and at different pre-damage levels (i.e., 30 %, 50 %, 75 %, 90 %, or 100 % of ultimate compressive strength in the pre-peak phase); then cured with self-healing periods of 1, 7, 28 or 90 days. Mechanical and hydraulic conductivity tests were performed on the pre-damaged specimens to monitor the self-healing changes. The results demonstrate that a significant self-healing capability does exist in the CPB materials due to the formed self-healing products from continuous cement hydration interior of the CPB matrix and carbonation of calcium hydroxide. The mechanical strength and hydraulic conductivity of pre-damaged specimens can be restored to similar values of the control specimens after 7 days and 28 days of self-healing periods, respectively. Furthermore, the study also reveals that the CPB specimens with high pre-damage levels (i.e., 75 %, 90 %, or 100 %) can even achieve up to 42 % higher mechanical strengths than the control specimens after 90 days of the self-healing period, indicating that the initiated cracks within the CPB matrix can ameliorate the hydration reactions favoring the self-healing performance. The results presented in the paper would have significant impacts and practical implications with respect to CPB structure design, mechanical stability, and durability.

{"title":"Investigation of crack self-healing behaviour and its impact on strength and permeability recovery in cemented paste tailings","authors":"Weizhou Quan, Mamadou Fall","doi":"10.1016/j.powtec.2025.120834","DOIUrl":"10.1016/j.powtec.2025.120834","url":null,"abstract":"<div><div>Cemented paste backfill (an engineered mixture of tailings, binder, and water), as one of the sustainable technological innovations for mining waste management, is used extensively around the world as a cementitious construction material in underground mines. The induced cracks within the CPB material tend to severely weaken the integrity and mechanical strength of the CPB structures as well as increase their permeability properties, undermining their safety, serviceability, durability, and environmental performance. However, no studies have been conducted to investigate the autogenous self-healing capability and behaviour of CPB. Therefore, this paper presents the results of an experimental study on the autogenous healing behaviour in CPB material to understand the self-healing mechanism and evaluate the self-healing efficiency through the recovery of mechanical and permeation properties. To this end, the CPB specimens were pre-damaged at different initial curing periods (i.e., 3, 7, and 28 days) and at different pre-damage levels (i.e., 30 %, 50 %, 75 %, 90 %, or 100 % of ultimate compressive strength in the pre-peak phase); then cured with self-healing periods of 1, 7, 28 or 90 days. Mechanical and hydraulic conductivity tests were performed on the pre-damaged specimens to monitor the self-healing changes. The results demonstrate that a significant self-healing capability does exist in the CPB materials due to the formed self-healing products from continuous cement hydration interior of the CPB matrix and carbonation of calcium hydroxide. The mechanical strength and hydraulic conductivity of pre-damaged specimens can be restored to similar values of the control specimens after 7 days and 28 days of self-healing periods, respectively. Furthermore, the study also reveals that the CPB specimens with high pre-damage levels (i.e., 75 %, 90 %, or 100 %) can even achieve up to 42 % higher mechanical strengths than the control specimens after 90 days of the self-healing period, indicating that the initiated cracks within the CPB matrix can ameliorate the hydration reactions favoring the self-healing performance. The results presented in the paper would have significant impacts and practical implications with respect to CPB structure design, mechanical stability, and durability.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"457 ","pages":"Article 120834"},"PeriodicalIF":4.5,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551951","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}

引用次数: 0

Simultaneous measurement of the 3D position, refractive index and droplet size of transparent spherical droplets using three-dimensional rainbow refractometry

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-28 DOI: 10.1016/j.powtec.2025.120818

Zhiwen Deng , Zhiming Lin , Xuecheng Wu , Yuxuan Zhao , Qiwen Jin , Yingchun Wu , Yongxin Zhang , Chenghang Zheng

In this study, we investigate three-dimensional rainbow refractometry (TDRR) as a method for estimating the 3D position, refractive index, and droplet size of transparent spherical droplets. The principles governing the variation of rainbow signals with axial position under cylindrical lens modulation are elucidated, allowing for estimation of the droplet’s axial position based on fringe rotation angles. We also present a novel calibration technique for absolute scattering angles in TDRR measurements and propose an innovative data processing approach. A comprehensive TDRR system has been constructed to validate measurements of monodisperse water droplet flows. The results indicate that the error in 3D position measurement is less than 3%, while the absolute error in refractive index measurement is below 0.0015 and droplet size errors remain under 5%. As a new technique for simultaneous droplet positioning and multi-parameter assessment, TDRR offers significant advantages for investigating droplet interactions and dynamics in a large space.

{"title":"Simultaneous measurement of the 3D position, refractive index and droplet size of transparent spherical droplets using three-dimensional rainbow refractometry","authors":"Zhiwen Deng , Zhiming Lin , Xuecheng Wu , Yuxuan Zhao , Qiwen Jin , Yingchun Wu , Yongxin Zhang , Chenghang Zheng","doi":"10.1016/j.powtec.2025.120818","DOIUrl":"10.1016/j.powtec.2025.120818","url":null,"abstract":"<div><div>In this study, we investigate three-dimensional rainbow refractometry (TDRR) as a method for estimating the 3D position, refractive index, and droplet size of transparent spherical droplets. The principles governing the variation of rainbow signals with axial position under cylindrical lens modulation are elucidated, allowing for estimation of the droplet’s axial position based on fringe rotation angles. We also present a novel calibration technique for absolute scattering angles in TDRR measurements and propose an innovative data processing approach. A comprehensive TDRR system has been constructed to validate measurements of monodisperse water droplet flows. The results indicate that the error in 3D position measurement is less than 3%, while the absolute error in refractive index measurement is below 0.0015 and droplet size errors remain under 5%. As a new technique for simultaneous droplet positioning and multi-parameter assessment, TDRR offers significant advantages for investigating droplet interactions and dynamics in a large space.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120818"},"PeriodicalIF":4.5,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529344","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}

引用次数: 0

3D rock fragmentation analysis using lidar, based on point cloud deep learning segmentation and synthetic data

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-28 DOI: 10.1016/j.powtec.2025.120861

Mojgan Faramarzi Hafshejani, Kamran Esmaeili

Accurate online measurement of particle size distribution is crucial in mining, tunnelling, and mineral processing industries to enable intelligent process control and optimization, ultimately enhancing efficiency and productivity. The current method for rock fragmentation relies on 2D image analysis, which is highly dependent on optimal lighting conditions, limiting its applicability and robustness in the challenging lighting environments commonly found in mining. This study diverges from the prevalent 2D image and photogrammetry approaches in rock fragmentation analysis, and pioneers a novel approach by harnessing laser scanner data for point cloud segmentation, offering a promising solution to overcome the limitations of image analysis techniques. By leveraging laser scanner data, a robust framework for rock fragmentation analysis is developed that is tailored to the specific challenges related to lighting situations. To avoid the laborious task of collecting and labelling point cloud datasets, this research introduces an innovative approach of using synthetic labeled datasets of scanned rockpiles. A platform is developed to automatically create and scan labeled point clouds of rock piles, facilitating the utilization of transfer learning. The synthetic 3D dataset was used to train a deep learning model for precise segmentation of rock instances in three-dimensional coordinates, providing an accurate representation of the rock object in 3D. The accuracy of the developed predictive model was tested and validated on experimental laser scanning data of three different rock piles. The proposed method depends on coordinate data instead of RGB information, rendering it particularly applicable in challenging conditions such as underground mining, night shifts, or situations where maintaining optimal lighting conditions is difficult or costly. The findings present a significant leap forward in rock fragmentation analysis, opening avenues for enhanced practices in diverse mining environments.

{"title":"3D rock fragmentation analysis using lidar, based on point cloud deep learning segmentation and synthetic data","authors":"Mojgan Faramarzi Hafshejani, Kamran Esmaeili","doi":"10.1016/j.powtec.2025.120861","DOIUrl":"10.1016/j.powtec.2025.120861","url":null,"abstract":"<div><div>Accurate online measurement of particle size distribution is crucial in mining, tunnelling, and mineral processing industries to enable intelligent process control and optimization, ultimately enhancing efficiency and productivity. The current method for rock fragmentation relies on 2D image analysis, which is highly dependent on optimal lighting conditions, limiting its applicability and robustness in the challenging lighting environments commonly found in mining. This study diverges from the prevalent 2D image and photogrammetry approaches in rock fragmentation analysis, and pioneers a novel approach by harnessing laser scanner data for point cloud segmentation, offering a promising solution to overcome the limitations of image analysis techniques. By leveraging laser scanner data, a robust framework for rock fragmentation analysis is developed that is tailored to the specific challenges related to lighting situations. To avoid the laborious task of collecting and labelling point cloud datasets, this research introduces an innovative approach of using synthetic labeled datasets of scanned rockpiles. A platform is developed to automatically create and scan labeled point clouds of rock piles, facilitating the utilization of transfer learning. The synthetic 3D dataset was used to train a deep learning model for precise segmentation of rock instances in three-dimensional coordinates, providing an accurate representation of the rock object in 3D. The accuracy of the developed predictive model was tested and validated on experimental laser scanning data of three different rock piles. The proposed method depends on coordinate data instead of RGB information, rendering it particularly applicable in challenging conditions such as underground mining, night shifts, or situations where maintaining optimal lighting conditions is difficult or costly. The findings present a significant leap forward in rock fragmentation analysis, opening avenues for enhanced practices in diverse mining environments.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120861"},"PeriodicalIF":4.5,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550816","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}

引用次数: 0

Study of amorphous powder cores with increased magnetic saturation and permeability

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-27 DOI: 10.1016/j.powtec.2025.120847

Ángel Sota Muñoz , Nerea Burgos , Valentina Zhukova , Ahmed Talaat , Julián González , Mikel Osinalde , Jose Manuel Martín

Soft magnetic composites (SMCs) made of amorphous powder typically result in low densities due to the brittleness of the amorphous, thereby providing poor magnetic properties. For this reason, this work focuses on mixing the particle sizes of amorphous powders to increase the packing, and therefore the compact density and magnetic properties. Enhanced packing density is obtained by mixing particle size fractions of 20–45 μm and 0–10 μm in a proportion of 73:27 vol%, respectively. Properties of the SMC made from the mixed fractions are compared with those made from each fraction using an Fe-Co composition ((Fe_0.425 Co_0.30 Si_0.125 B_0.15)_96.5Nb₃Cu_0.5). The mixing of fractions shows an increase of 10 % in density, thus reducing interparticle voids and enhancing magnetic saturation and permeability. By contrast, lower power losses are provided by the SMC fabricated with the 0–10 μm fraction due to lower eddy currents. A comparative study on magnetic properties and power losses of SMCs made from the mixed fractions for four compositions reveal that highest permeability (μ’ = 34.5) is achieved with composition (Fe_0.46 Co_0.30 Si_0.09 B_0.10 P_0.05)_96.5Nb₃Cu_0.5 and lowest power losses at high frequency (3437 mW/cm³ at 1 MHz and B = 50 mT) with Fe_72.5 Si_12.5 B₁₅ after annealing and subsequent resin infiltration.

{"title":"Study of amorphous powder cores with increased magnetic saturation and permeability","authors":"Ángel Sota Muñoz , Nerea Burgos , Valentina Zhukova , Ahmed Talaat , Julián González , Mikel Osinalde , Jose Manuel Martín","doi":"10.1016/j.powtec.2025.120847","DOIUrl":"10.1016/j.powtec.2025.120847","url":null,"abstract":"<div><div>Soft magnetic composites (SMCs) made of amorphous powder typically result in low densities due to the brittleness of the amorphous, thereby providing poor magnetic properties. For this reason, this work focuses on mixing the particle sizes of amorphous powders to increase the packing, and therefore the compact density and magnetic properties. Enhanced packing density is obtained by mixing particle size fractions of 20–45 μm and 0–10 μm in a proportion of 73:27 vol%, respectively. Properties of the SMC made from the mixed fractions are compared with those made from each fraction using an Fe-Co composition ((Fe<sub>0.425</sub> Co<sub>0.30</sub> Si<sub>0.125</sub> B<sub>0.15</sub>)<sub>96.5</sub>Nb<sub>3</sub>Cu<sub>0.5</sub>). The mixing of fractions shows an increase of 10 % in density, thus reducing interparticle voids and enhancing magnetic saturation and permeability. By contrast, lower power losses are provided by the SMC fabricated with the 0–10 μm fraction due to lower eddy currents. A comparative study on magnetic properties and power losses of SMCs made from the mixed fractions for four compositions reveal that highest permeability (μ’ = 34.5) is achieved with composition (Fe<sub>0.46</sub> Co<sub>0.30</sub> Si<sub>0.09</sub> B<sub>0.10</sub> P<sub>0.05</sub>)<sub>96.5</sub>Nb<sub>3</sub>Cu<sub>0.5</sub> and lowest power losses at high frequency (3437 mW/cm<sup>3</sup> at 1 MHz and B = 50 mT) with Fe<sub>72.5</sub> Si<sub>12.5</sub> B<sub>15</sub> after annealing and subsequent resin infiltration.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120847"},"PeriodicalIF":4.5,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550821","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}

引用次数: 0

Influence of ballast gradation on repose angle using large-scale hopper flow tests and DEM simulation

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-27 DOI: 10.1016/j.powtec.2025.120852

Cheng Chen , Shao-shuo Li , Jun-feng Li , Lei Zhang , Juan Yang

This study investigates the influence of ballast gradation on the repose angle through a series of large-scale hopper flow tests and discrete element method (DEM) simulations. Bulk-scale and micro analyses of the entire ballast pile formation process reveal three stages: platform-stacking, peak-stacking, and peak-shaving, with particle interlocking during these stages playing a crucial role in establishing the angle of repose. Results indicate that ballast gradation significantly affects the repose angle, the maximum repose angle is observed at d₅₀ = 40.0 mm, within the tested range of 36.8 mm to 45.0 mm. As the gradation of the ballast transitions from uniform to non-uniform, the repose angle initially increases and then decreases, peaking at d₅₀ = 40.0 mm and C_u = 1.46. The spatial distribution of particles within the ballast pile follows a distinct pattern, large particles within the ballast pile is relatively uniform, while small and medium particles are more concentrated in the core regions. A better particle gradation allows smaller particles to fill the voids between larger particles, thereby optimizing the load distribution between strong and weak force chains. This research underscores the importance of proper gradation for ensuring stability and effective load-bearing capacity in ballast systems.

{"title":"Influence of ballast gradation on repose angle using large-scale hopper flow tests and DEM simulation","authors":"Cheng Chen , Shao-shuo Li , Jun-feng Li , Lei Zhang , Juan Yang","doi":"10.1016/j.powtec.2025.120852","DOIUrl":"10.1016/j.powtec.2025.120852","url":null,"abstract":"<div><div>This study investigates the influence of ballast gradation on the repose angle through a series of large-scale hopper flow tests and discrete element method (DEM) simulations. Bulk-scale and micro analyses of the entire ballast pile formation process reveal three stages: platform-stacking, peak-stacking, and peak-shaving, with particle interlocking during these stages playing a crucial role in establishing the angle of repose. Results indicate that ballast gradation significantly affects the repose angle, the maximum repose angle is observed at <em>d</em><sub>50</sub> = 40.0 mm, within the tested range of 36.8 mm to 45.0 mm. As the gradation of the ballast transitions from uniform to non-uniform, the repose angle initially increases and then decreases, peaking at <em>d</em><sub>50</sub> = 40.0 mm and <em>C</em><sub>u</sub> = 1.46. The spatial distribution of particles within the ballast pile follows a distinct pattern, large particles within the ballast pile is relatively uniform, while small and medium particles are more concentrated in the core regions. A better particle gradation allows smaller particles to fill the voids between larger particles, thereby optimizing the load distribution between strong and weak force chains. This research underscores the importance of proper gradation for ensuring stability and effective load-bearing capacity in ballast systems.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120852"},"PeriodicalIF":4.5,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550824","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}

引用次数: 0

Numerical simulation of proppant transport with multi-stage alternating injection in CO2 hybrid fracturing

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-26 DOI: 10.1016/j.powtec.2025.120840

Yong Zheng , Zhigang Wang , Haoyu Chen , Hai Huang , Jun Ni , Liangbin Dou , Haizhu Wang , Bin Wang

Effective proppant placement has been one of the key objectives of reservoir stimulation. CO₂ hybrid fracturing is promising for the economic production of unconventional reservoirs, however, there is a lack of understanding of proppant transport within the rough fractures associated with it. In this study, a validated CFD-DEM model is used to simulate proppant transport with multi-stage alternating injection in CO₂ hybrid fracturing, focusing on evaluating the advantages of alternating injection within a rough fracture as well as the influence laws of key parameters. The simulation results show that the use of multi-stage alternating injection of proppant with different fluids in CO₂ hybrid fracturing can obtain better proppant placement than single fluid continuous pumping, with 36.4 % and 4.4 % higher proppant dune lengths, and 3.51 % and 2.3 % higher dune placement rate than single CO₂ pumping and water pumping, respectively. The optimal number of injection stages in multi-stage alternating injection of proppant is 4, while the optimal segment plug length ratio of CO₂ and water is 3:1. The best dune length and placement rate are obtained when the CO₂ segment plug is injected at a velocity of 0.1 m/s, but when the CO₂ segment plug is injected at a velocity of 0.2 m/s, it is favorable for the safety of the pipeline and equipment during fracturing operation.

{"title":"Numerical simulation of proppant transport with multi-stage alternating injection in CO2 hybrid fracturing","authors":"Yong Zheng , Zhigang Wang , Haoyu Chen , Hai Huang , Jun Ni , Liangbin Dou , Haizhu Wang , Bin Wang","doi":"10.1016/j.powtec.2025.120840","DOIUrl":"10.1016/j.powtec.2025.120840","url":null,"abstract":"<div><div>Effective proppant placement has been one of the key objectives of reservoir stimulation. CO<sub>2</sub> hybrid fracturing is promising for the economic production of unconventional reservoirs, however, there is a lack of understanding of proppant transport within the rough fractures associated with it. In this study, a validated CFD-DEM model is used to simulate proppant transport with multi-stage alternating injection in CO<sub>2</sub> hybrid fracturing, focusing on evaluating the advantages of alternating injection within a rough fracture as well as the influence laws of key parameters. The simulation results show that the use of multi-stage alternating injection of proppant with different fluids in CO<sub>2</sub> hybrid fracturing can obtain better proppant placement than single fluid continuous pumping, with 36.4 % and 4.4 % higher proppant dune lengths, and 3.51 % and 2.3 % higher dune placement rate than single CO<sub>2</sub> pumping and water pumping, respectively. The optimal number of injection stages in multi-stage alternating injection of proppant is 4, while the optimal segment plug length ratio of CO<sub>2</sub> and water is 3:1. The best dune length and placement rate are obtained when the CO<sub>2</sub> segment plug is injected at a velocity of 0.1 m/s, but when the CO<sub>2</sub> segment plug is injected at a velocity of 0.2 m/s, it is favorable for the safety of the pipeline and equipment during fracturing operation.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120840"},"PeriodicalIF":4.5,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550825","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}

引用次数: 0

Two-stage synthesis of spherical iron powders from steel industry by product

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-25 DOI: 10.1016/j.powtec.2025.120851

Kameswara Srikar Sista , Abhijeet Premkumar Moon , Srinivas Dwarapudi , Siddhartha Misra , Chenna Rao Borra

Spherical iron powders are often used in high end applications like metal injection molding additive manufacturing, and soft magnetics due to their sphere morphology, high density and good flowability. Till date, manufacturing processes like gas atomization and carbonyl process are the only available routes for synthesis of spherical iron. In this work a novel approach of obtaining spherical iron powder via a two stage (reduction + plasma spheroidization) process by use of iron oxide by-product from steel industry is proposed. Physico-chemical characterization of powders reveals that irregular iron powders with high purity (Fe (T)- 98.2 wt%, Fe(M)- 96.8 wt%), low apparent density (1.1 g/cc) and high surface area (0.37 m²/g) are successfully synthesized at optimal conditions of reduction (850 °C, 300 min). Further, plasma spheroidization of this irregular iron powders at optimized process parameters (11.5 KW plasma power, 6.5 g/min feed rate) generated spherical powders with high purity (Fe (T)- 97.8 wt%, Fe(M)- 95.6 wt%), high apparent density (3.84 g/cc) and good flowability (8.8 s/50 g). Present work fosters a sustainable and scalable approach for synthesis of two different grades of iron powder having diverse applications from a single feed source.

{"title":"Two-stage synthesis of spherical iron powders from steel industry by product","authors":"Kameswara Srikar Sista , Abhijeet Premkumar Moon , Srinivas Dwarapudi , Siddhartha Misra , Chenna Rao Borra","doi":"10.1016/j.powtec.2025.120851","DOIUrl":"10.1016/j.powtec.2025.120851","url":null,"abstract":"<div><div>Spherical iron powders are often used in high end applications like metal injection molding additive manufacturing, and soft magnetics due to their sphere morphology, high density and good flowability. Till date, manufacturing processes like gas atomization and carbonyl process are the only available routes for synthesis of spherical iron. In this work a novel approach of obtaining spherical iron powder via a two stage (reduction + plasma spheroidization) process by use of iron oxide by-product from steel industry is proposed. Physico-chemical characterization of powders reveals that irregular iron powders with high purity (Fe (T)- 98.2 wt%, Fe(M)- 96.8 wt%), low apparent density (1.1 g/cc) and high surface area (0.37 m<sup>2</sup>/g) are successfully synthesized at optimal conditions of reduction (850 °C, 300 min). Further, plasma spheroidization of this irregular iron powders at optimized process parameters (11.5 KW plasma power, 6.5 g/min feed rate) generated spherical powders with high purity (Fe (T)- 97.8 wt%, Fe(M)- 95.6 wt%), high apparent density (3.84 g/cc) and good flowability (8.8 s/50 g). Present work fosters a sustainable and scalable approach for synthesis of two different grades of iron powder having diverse applications from a single feed source.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120851"},"PeriodicalIF":4.5,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512398","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}

引用次数: 0

Powder bed fusion – Laser beam in reactive atmospheres – Ignition limits for Fe and Ti-6Al-4V powder blends in CO2 and N2

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-25 DOI: 10.1016/j.powtec.2025.120843

C. Felber , M. Köberl , E.A. Jägle

Powder bed fusion – laser beam (PBF-LB) in reactive CO₂ and N₂ atmospheres affect material properties, such as ductility and strength due to their uptake during processing. This can be exploited to manufacture in-situ particle reinforced materials. In Fe-based materials, in-situ precipitation is limited, thus Ti is added to increase the material-gas-interaction. However, the fraction of Ti in Fe-Ti blends must be limited, as laser exposure in these reactive atmospheres can lead to a strongly exothermic and self-sustained combustion reaction in the powder bed. In this study, the occurring combustion reaction and ignition limits are investigated. The laser power, speed, and spot size, as well as heat accumulation influence the onset of the combustion reaction. Based on our results, a lower limit for which no ignition occurs was determined to ca. 23 wt% Ti. At higher Ti concentrations, reasonable PBF-LB parameters may lead to ignition. The combustion products contain high numbers of oxides and carbides and consist of a combustion zone and a molten and sintered area below. These results show that undesired reactions in the powder bed can be controlled, and that Ti-containing powder blends are safely processable in CO₂ and N₂ atmosphere if the Ti fraction is limited.

{"title":"Powder bed fusion – Laser beam in reactive atmospheres – Ignition limits for Fe and Ti-6Al-4V powder blends in CO2 and N2","authors":"C. Felber , M. Köberl , E.A. Jägle","doi":"10.1016/j.powtec.2025.120843","DOIUrl":"10.1016/j.powtec.2025.120843","url":null,"abstract":"<div><div>Powder bed fusion – laser beam (PBF-LB) in reactive CO<sub>2</sub> and N<sub>2</sub> atmospheres affect material properties, such as ductility and strength due to their uptake during processing. This can be exploited to manufacture in-situ particle reinforced materials. In Fe-based materials, in-situ precipitation is limited, thus Ti is added to increase the material-gas-interaction. However, the fraction of Ti in Fe-Ti blends must be limited, as laser exposure in these reactive atmospheres can lead to a strongly exothermic and self-sustained combustion reaction in the powder bed. In this study, the occurring combustion reaction and ignition limits are investigated. The laser power, speed, and spot size, as well as heat accumulation influence the onset of the combustion reaction. Based on our results, a lower limit for which no ignition occurs was determined to ca. 23 wt% Ti. At higher Ti concentrations, reasonable PBF-LB parameters may lead to ignition. The combustion products contain high numbers of oxides and carbides and consist of a combustion zone and a molten and sintered area below. These results show that undesired reactions in the powder bed can be controlled, and that Ti-containing powder blends are safely processable in CO<sub>2</sub> and N<sub>2</sub> atmosphere if the Ti fraction is limited.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120843"},"PeriodicalIF":4.5,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519206","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}

引用次数: 0

The effects of thermal properties on the interphase drag of supercritical water-particle flow

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-25 DOI: 10.1016/j.powtec.2025.120849

Xiaoyu Li, Bowei Zhang, Yi Li, Hui Jin

The drag of particle clusters is important for the investigation of fluidized beds, but there is no accurate correlation available. The effects of nonlinear physical properties on the drag of particle clusters in supercritical water (SCW) fluidized beds cannot be overlooked either. This work conducts a simulation investigation on the interphase drag of SCW-particle flow. The results reveal that an increase in density leads to a decrease in the drag coefficient C_d. This results in a positive correlation between the drag coefficient and particle temperature. The effects of Reynolds number (Re) and void fraction (ε) on the density distribution further influence the normalized drag coefficient C. The distributions of dimensionless velocity and kinetic energy indicate that the conversion rate of pressure potential energy to kinetic energy in SCW is lower than that in constant property flow (CPF). The distributions of C_d and C of sub-particles show that downstream particles are most influenced by variations in density under different conditions. A model for the effects of nonlinear physical properties is established based on the C. Analysis of the results from CPF reveals that the exponent β in this work is primarily a function of ε. A correlation between the exponent β and ε is established. A drag coefficient model for particle flow in SCW is developed through the coupling of multiple models.

{"title":"The effects of thermal properties on the interphase drag of supercritical water-particle flow","authors":"Xiaoyu Li, Bowei Zhang, Yi Li, Hui Jin","doi":"10.1016/j.powtec.2025.120849","DOIUrl":"10.1016/j.powtec.2025.120849","url":null,"abstract":"<div><div>The drag of particle clusters is important for the investigation of fluidized beds, but there is no accurate correlation available. The effects of nonlinear physical properties on the drag of particle clusters in supercritical water (SCW) fluidized beds cannot be overlooked either. This work conducts a simulation investigation on the interphase drag of SCW-particle flow. The results reveal that an increase in density leads to a decrease in the drag coefficient <em>C</em><sub><em>d</em></sub>. This results in a positive correlation between the drag coefficient and particle temperature. The effects of Reynolds number (<em>Re</em>) and void fraction (<em>ε</em>) on the density distribution further influence the normalized drag coefficient <em>C</em>. The distributions of dimensionless velocity and kinetic energy indicate that the conversion rate of pressure potential energy to kinetic energy in SCW is lower than that in constant property flow (CPF). The distributions of <em>C</em><sub><em>d</em></sub> and <em>C</em> of sub-particles show that downstream particles are most influenced by variations in density under different conditions. A model for the effects of nonlinear physical properties is established based on the <em>C</em>. Analysis of the results from CPF reveals that the exponent <em>β</em> in this work is primarily a function of <em>ε</em>. A correlation between the exponent <em>β</em> and <em>ε</em> is established. A drag coefficient model for particle flow in SCW is developed through the coupling of multiple models.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120849"},"PeriodicalIF":4.5,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519203","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}

引用次数: 0

Research on the pore structure and gas adsorption/desorption characteristics of tectonic coal in minor fault zone: Implications for coal and gas outbursts

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-02-25 DOI: 10.1016/j.powtec.2025.120846

Shangkun Shen , Haifeng Wang , Tianwei Ren , Zhiyuan Wang

Minor faults, widely prevalent as small-scale tectonism in mining work face, are one of the important factors influencing coal and gas outbursts (CGO). This paper examined the pore structure, gas adsorption and desorption characteristics of coal samples at varying distances from fault and analyzed their interrelationships. The results show that fault has a significant effect on modifying mesopore and macropore, with a lesser effect on micropore. As distance from the fault decreases, there is an increasing trend in the gas's maximum adsorption volume, desorption rate, desorption volume, expansion energy and initial emission speed. Micropore is not the sole factor influencing gas adsorption, coal mineral composition or other factors also affect gas adsorption performance, while mesopore and macropore control gas desorption characteristics. Powdering significantly enhances gas expansion energy, with gas expansion energy in 0.074–0.2 mm being 7.19 times that of 1-3 mm, greatly increasing the risk of CGO. The influence range of the hanging wall is 17.35 m, which is 1.16 times that of the footwall, indicating a notably stronger modification effect of the fault on the hanging wall. The research results reveal the mechanism of how minor fault affects the microphysical structure and macroscopic adsorption and desorption characteristics on outburst coal seams, providing a foundation for the prevention and control of CGO in coal seams containing minor faults.

{"title":"Research on the pore structure and gas adsorption/desorption characteristics of tectonic coal in minor fault zone: Implications for coal and gas outbursts","authors":"Shangkun Shen , Haifeng Wang , Tianwei Ren , Zhiyuan Wang","doi":"10.1016/j.powtec.2025.120846","DOIUrl":"10.1016/j.powtec.2025.120846","url":null,"abstract":"<div><div>Minor faults, widely prevalent as small-scale tectonism in mining work face, are one of the important factors influencing coal and gas outbursts (CGO). This paper examined the pore structure, gas adsorption and desorption characteristics of coal samples at varying distances from fault and analyzed their interrelationships. The results show that fault has a significant effect on modifying mesopore and macropore, with a lesser effect on micropore. As distance from the fault decreases, there is an increasing trend in the gas's maximum adsorption volume, desorption rate, desorption volume, expansion energy and initial emission speed. Micropore is not the sole factor influencing gas adsorption, coal mineral composition or other factors also affect gas adsorption performance, while mesopore and macropore control gas desorption characteristics. Powdering significantly enhances gas expansion energy, with gas expansion energy in 0.074–0.2 mm being 7.19 times that of 1-3 mm, greatly increasing the risk of CGO. The influence range of the hanging wall is 17.35 m, which is 1.16 times that of the footwall, indicating a notably stronger modification effect of the fault on the hanging wall. The research results reveal the mechanism of how minor fault affects the microphysical structure and macroscopic adsorption and desorption characteristics on outburst coal seams, providing a foundation for the prevention and control of CGO in coal seams containing minor faults.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"456 ","pages":"Article 120846"},"PeriodicalIF":4.5,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512402","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}

引用次数: 0