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, Available online 10 August 2024,
https://doi.org/10.1007/s12613-024-2985-6
Abstract:
Cemented tailings backfill (CTB) not only boosts mining safety and cuts surface environmental pollution but also recovers ores previously retained as pillars, thereby improving resource utilization. The use of alternative reinforcing products, such as steel fiber (SF), has continuously strengthened CTB into SFCTB. This approach prevents strength decreases over time and reinforces its long-term durability, especially when mining ore in adjacent underground stopes. In this study, various microstructure and strength tests were performed on SFCTB, considering steel fiber ratio and electromagnetic induction strength effects. Lab findings show that combining steel fibers and their distribution dominantly influences the improvement of the fill’s strength. Fill’s strength rises by fiber insertion and has an evident correlation with fiber insertion and magnetic induction strength. When magnetic induction strength is 3 × 10−4 T, peak uniaxial compressive stress reaches 5.73 MPa for a fiber ratio of 2.0vol%. The cracks’ expansion mainly started from the specimen’s upper part, which steadily expanded downward by increasing the load until damage occurred. The doping of steel fiber and its directional distribution delayed crack development. When the doping of steel fiber was 2.0vol%, SFCTBs showed excellent ductility characteristics. The energy required for fills to reach destruction increases when steel-fiber insertion and magnetic induction strength increase. This study provides notional references for steel fibers as underground filling additives to enhance the fill’s durability in the course of mining operations.
Cemented tailings backfill (CTB) not only boosts mining safety and cuts surface environmental pollution but also recovers ores previously retained as pillars, thereby improving resource utilization. The use of alternative reinforcing products, such as steel fiber (SF), has continuously strengthened CTB into SFCTB. This approach prevents strength decreases over time and reinforces its long-term durability, especially when mining ore in adjacent underground stopes. In this study, various microstructure and strength tests were performed on SFCTB, considering steel fiber ratio and electromagnetic induction strength effects. Lab findings show that combining steel fibers and their distribution dominantly influences the improvement of the fill’s strength. Fill’s strength rises by fiber insertion and has an evident correlation with fiber insertion and magnetic induction strength. When magnetic induction strength is 3 × 10−4 T, peak uniaxial compressive stress reaches 5.73 MPa for a fiber ratio of 2.0vol%. The cracks’ expansion mainly started from the specimen’s upper part, which steadily expanded downward by increasing the load until damage occurred. The doping of steel fiber and its directional distribution delayed crack development. When the doping of steel fiber was 2.0vol%, SFCTBs showed excellent ductility characteristics. The energy required for fills to reach destruction increases when steel-fiber insertion and magnetic induction strength increase. This study provides notional references for steel fibers as underground filling additives to enhance the fill’s durability in the course of mining operations.
, Available online 16 July 2024,
https://doi.org/10.1007/s12613-024-2973-x
Abstract:
Silver selenide (Ag2Se) stands out as a promising thermoelectric (TE) material, particularly for applications near room temperatures. This research presents a novel approach for the fabrication of bulk Ag2Se samples at a relatively low temperature (170°C) using the cold sintering process (CSP) with AgNO3 solution as a transient liquid agent. The effect of AgNO3 addition during CSP on the microstructure and TE properties was investigated. The results from phase, composition and microstructure analyses showed that the introduction of AgNO3 solution induced the formation of Ag nano-precipitates within the Ag2Se matrix. Although the nano-precipitates do not affect the phase and crystal structure of orthorhombic β-Ag2Se, they suppressed crystal growth, leading to reduced crystallite sizes. The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density. Consequently, these effects contributed to significantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorporated. This resulted in an improved average power factor from ~1540 µW·m−1·K−2 for pure Ag2Se to ~1670 µW·m−1·K−2 for Ag2Se with additional Ag precipitates. However, excessive Ag addition had a detrimental effect on the power factor. Furthermore, thermal conductivity was effectively suppressed in Ag2Se fabricated using AgNO3-assisted CSP, attributed to enhanced phonon scattering at crystal interfaces, pores, and Ag nano-precipitates. The highest figure-of-merit (zT) of 0.92 at 300 K was achieved for the Ag2Se with 0.5wt% Ag during CSP fabrication, equivalent to >20% improvement compared to the controlled Ag2Se without extra Ag solution. Thus, the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag2Se and enhance its TE performance at room temperature.
Silver selenide (Ag2Se) stands out as a promising thermoelectric (TE) material, particularly for applications near room temperatures. This research presents a novel approach for the fabrication of bulk Ag2Se samples at a relatively low temperature (170°C) using the cold sintering process (CSP) with AgNO3 solution as a transient liquid agent. The effect of AgNO3 addition during CSP on the microstructure and TE properties was investigated. The results from phase, composition and microstructure analyses showed that the introduction of AgNO3 solution induced the formation of Ag nano-precipitates within the Ag2Se matrix. Although the nano-precipitates do not affect the phase and crystal structure of orthorhombic β-Ag2Se, they suppressed crystal growth, leading to reduced crystallite sizes. The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density. Consequently, these effects contributed to significantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorporated. This resulted in an improved average power factor from ~1540 µW·m−1·K−2 for pure Ag2Se to ~1670 µW·m−1·K−2 for Ag2Se with additional Ag precipitates. However, excessive Ag addition had a detrimental effect on the power factor. Furthermore, thermal conductivity was effectively suppressed in Ag2Se fabricated using AgNO3-assisted CSP, attributed to enhanced phonon scattering at crystal interfaces, pores, and Ag nano-precipitates. The highest figure-of-merit (zT) of 0.92 at 300 K was achieved for the Ag2Se with 0.5wt% Ag during CSP fabrication, equivalent to >20% improvement compared to the controlled Ag2Se without extra Ag solution. Thus, the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag2Se and enhance its TE performance at room temperature.
, Available online 19 April 2024
Abstract:
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
, Available online 1 August 2024,
https://doi.org/10.1007/s12613-024-2980-y
Abstract:
Complex studies of new Mg–Zn–Y–Zr system alloys have been carried out. The content range for the formation of the two-phase structure MgSS (Mg solid solution) + LPSO (long-period stacking ordered) in alloys of the Mg–Zn–Y–Zr system was determined by thermodynamic calculations. The effect of heat treatment regimes on microstructure, mechanical, and corrosion properties was investigated. The fluidity, hot cracking tendency, and ignition temperature of the alloys were determined. The best combination of castability, mechanical, and corrosion properties was found for the Mg–2.4Zn–4Y–0.8Zr alloy. The alloys studied are superior to their industrial counterparts in terms of technological properties, while maintain high corrosion and mechanical properties. The increased level of properties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.
Complex studies of new Mg–Zn–Y–Zr system alloys have been carried out. The content range for the formation of the two-phase structure MgSS (Mg solid solution) + LPSO (long-period stacking ordered) in alloys of the Mg–Zn–Y–Zr system was determined by thermodynamic calculations. The effect of heat treatment regimes on microstructure, mechanical, and corrosion properties was investigated. The fluidity, hot cracking tendency, and ignition temperature of the alloys were determined. The best combination of castability, mechanical, and corrosion properties was found for the Mg–2.4Zn–4Y–0.8Zr alloy. The alloys studied are superior to their industrial counterparts in terms of technological properties, while maintain high corrosion and mechanical properties. The increased level of properties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.
, Available online 11 July 2024,
https://doi.org/10.1007/s12613-024-2972-y
Abstract:
Facing the complex variable high-temperature environment, electromagnetic wave (EMW) absorbing materials maintaining high stability and satisfying absorbing properties is essential. This study focused on the synthesis and EMW absorbing performance evaluation of TiN/Fe2N/C composite materials, which were prepared using electrostatic spinning followed by a high-temperature nitridation process. The TiN/Fe2N/C fibers constructed a well-developed conductive network that generates considerable conduction loss. The heterogeneous interfaces between different components generated a significant level of interfacial polarization. Thanks to the synergistic effect of stable dielectric loss and optimized impedance matching, the TiN/Fe2N/C composite materials demonstrated excellent and stable absorption performance across a wide temperature range (293–453 K). Moreover, TiN/Fe2N/C-15 achieved a minimum reflection loss (RL) of –48.01 dB and an effective absorption bandwidth (EAB) of 3.64 GHz at 2.1 mm and 373 K. This work provides new insights into the development of high-efficiency and stabile EMW absorbing materials under complex variable high-temperature conditions.
Facing the complex variable high-temperature environment, electromagnetic wave (EMW) absorbing materials maintaining high stability and satisfying absorbing properties is essential. This study focused on the synthesis and EMW absorbing performance evaluation of TiN/Fe2N/C composite materials, which were prepared using electrostatic spinning followed by a high-temperature nitridation process. The TiN/Fe2N/C fibers constructed a well-developed conductive network that generates considerable conduction loss. The heterogeneous interfaces between different components generated a significant level of interfacial polarization. Thanks to the synergistic effect of stable dielectric loss and optimized impedance matching, the TiN/Fe2N/C composite materials demonstrated excellent and stable absorption performance across a wide temperature range (293–453 K). Moreover, TiN/Fe2N/C-15 achieved a minimum reflection loss (RL) of –48.01 dB and an effective absorption bandwidth (EAB) of 3.64 GHz at 2.1 mm and 373 K. This work provides new insights into the development of high-efficiency and stabile EMW absorbing materials under complex variable high-temperature conditions.
, Available online 12 June 2024,
https://doi.org/10.1007/s12613-024-2954-0
Abstract:
Iron oxide (Fe2O3) emerges as a highly attractive anode candidate among rapidly expanding energy storage market. Nonetheless, its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life. In this work, an approach is pioneered for preparing high-performance Fe2O3 anode materials, by innovatively synthesizing a triple-layer yolk-shell Fe2O3 uniformly coated with a conductive polypyrrole (Ppy) layer (Fe2O3@Ppy-TLY). The uniform polypyrrole coating introduces more reaction sites and adsorption sites, and maintains structure stability through charge-discharge process. In the uses as lithium-ion battery electrodes, Fe2O3@Ppy-TLY demonstrates high reversible specific capacity (maintaining a discharge capacity of 1375.11 mAh·g−1 after 500 cycles at 1 C), exceptional cycling stability (retaining the steady charge-discharge performance at 544.33 mAh·g−1 after 6000 ultrafast charge-discharge cycles at a 10 C current density), and outstanding high current charge-discharge performance (retaining a reversible capacity of 156.75 mAh·g−1 after 10000 cycles at 15 C), thereby exhibiting superior lithium storage performance. This work introduces innovative advancements for Fe2O3 anode design, aiming to enhance its performance in energy storage fields.
Iron oxide (Fe2O3) emerges as a highly attractive anode candidate among rapidly expanding energy storage market. Nonetheless, its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life. In this work, an approach is pioneered for preparing high-performance Fe2O3 anode materials, by innovatively synthesizing a triple-layer yolk-shell Fe2O3 uniformly coated with a conductive polypyrrole (Ppy) layer (Fe2O3@Ppy-TLY). The uniform polypyrrole coating introduces more reaction sites and adsorption sites, and maintains structure stability through charge-discharge process. In the uses as lithium-ion battery electrodes, Fe2O3@Ppy-TLY demonstrates high reversible specific capacity (maintaining a discharge capacity of 1375.11 mAh·g−1 after 500 cycles at 1 C), exceptional cycling stability (retaining the steady charge-discharge performance at 544.33 mAh·g−1 after 6000 ultrafast charge-discharge cycles at a 10 C current density), and outstanding high current charge-discharge performance (retaining a reversible capacity of 156.75 mAh·g−1 after 10000 cycles at 15 C), thereby exhibiting superior lithium storage performance. This work introduces innovative advancements for Fe2O3 anode design, aiming to enhance its performance in energy storage fields.
, Available online 6 June 2024,
https://doi.org/10.1007/s12613-024-2952-2
Abstract:
Hexagonal MnMX-based (M = Co or Ni, X = Si or Ge) alloys exhibit giant reversible barocaloric effects. However, giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders, and inevitably bring the deterioration of mechanical properties and formability. Grain fragmentation can bring degradation of structural transformation entropy change during cyclic application and removal of pressure. In this paper, giant reversible barocaloric effects with high thermal cycle stability can be achieved in the epoxy bonded (MnCoGe)0.96(CuCoSn)0.04 composite. Giant reversible isothermal entropy change of 43.0 J∙kg-1∙K-1 and adiabatic temperature change from barocaloric effects (∆TBCE) of 15.6 K can be obtained within a wide temperature span of 30 K at 360 MPa, which is mainly attributed to the integration of the change in the transition temperature driven by pressure of −101 K∙GPa-1 and suitable thermal hysteresis of 11.1 K. Further, the variation of reversible ∆TBCE against the applied hydrostatic pressure reaches up to 43 K∙GPa-1, which is at the highest level among the other reported giant barocaloric compounds. More importantly, after 60 thermal cycles, the composite does not break and the calorimetric curves coincide well, demonstrating good thermal cycle stability.
Hexagonal MnMX-based (M = Co or Ni, X = Si or Ge) alloys exhibit giant reversible barocaloric effects. However, giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders, and inevitably bring the deterioration of mechanical properties and formability. Grain fragmentation can bring degradation of structural transformation entropy change during cyclic application and removal of pressure. In this paper, giant reversible barocaloric effects with high thermal cycle stability can be achieved in the epoxy bonded (MnCoGe)0.96(CuCoSn)0.04 composite. Giant reversible isothermal entropy change of 43.0 J∙kg-1∙K-1 and adiabatic temperature change from barocaloric effects (∆TBCE) of 15.6 K can be obtained within a wide temperature span of 30 K at 360 MPa, which is mainly attributed to the integration of the change in the transition temperature driven by pressure of −101 K∙GPa-1 and suitable thermal hysteresis of 11.1 K. Further, the variation of reversible ∆TBCE against the applied hydrostatic pressure reaches up to 43 K∙GPa-1, which is at the highest level among the other reported giant barocaloric compounds. More importantly, after 60 thermal cycles, the composite does not break and the calorimetric curves coincide well, demonstrating good thermal cycle stability.
, Available online 11 May 2024,
https://doi.org/10.1007/s12613-024-2932-6
Abstract:
To enhance the microbiologically influenced corrosion (MIC) resistance of FeCoNiCrMn high entropy alloy (HEAs), a series of FexCu(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs were prepared. Microstructural characteristics, corrosion behavior (morphology observation and electrochemical properties), and antimicrobial performance of FexCu(1−x)CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa. The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties. Results revealed that all FexCu(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs exhibited an FCC (face centered cubic) phase, with significant grain refinement observed in Fe0.75Cu0.25CoNiCrMn HEA. Electrochemical tests indicated that Fe0.75Cu0.25CoNiCrMn HEA demonstrated lower corrosion current density (icorr) and pitting potential (Epit) compared to other FexCu(1−x)CoNiCrMn HEAs in P. aeruginosa-inoculated medium, exhibiting superior resistance to MIC. Anti-microbial tests showed that after 14 d of immersion, Fe0.75Cu0.25CoNiCrMn achieved an antibacterial rate of 89.5%, effectively inhibiting the adhesion and biofilm formation of P. aeruginosa, thereby achieving resistance to MIC.
To enhance the microbiologically influenced corrosion (MIC) resistance of FeCoNiCrMn high entropy alloy (HEAs), a series of FexCu(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs were prepared. Microstructural characteristics, corrosion behavior (morphology observation and electrochemical properties), and antimicrobial performance of FexCu(1−x)CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa. The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties. Results revealed that all FexCu(1−x)CoNiCrMn (x = 1, 0.75, 0.5, and 0.25) HEAs exhibited an FCC (face centered cubic) phase, with significant grain refinement observed in Fe0.75Cu0.25CoNiCrMn HEA. Electrochemical tests indicated that Fe0.75Cu0.25CoNiCrMn HEA demonstrated lower corrosion current density (icorr) and pitting potential (Epit) compared to other FexCu(1−x)CoNiCrMn HEAs in P. aeruginosa-inoculated medium, exhibiting superior resistance to MIC. Anti-microbial tests showed that after 14 d of immersion, Fe0.75Cu0.25CoNiCrMn achieved an antibacterial rate of 89.5%, effectively inhibiting the adhesion and biofilm formation of P. aeruginosa, thereby achieving resistance to MIC.
, Available online 8 April 2024,
https://doi.org/10.1007/s12613-024-2904-x
Abstract:
The direct reduction process is an important development direction of low-carbon ironmaking and efficient comprehensive utilization of poly-metallic iron ore, such as titanomagnetite. However, the defluidization of reduced iron particles with a high metallization degree at a high temperature will seriously affect the operation of fluidized bed reduction. Coupling the pre-oxidation enhancing reduction and the particle surface modification of titanomagnetite, the behavior and mechanism of pre-oxidation improvement on fluidization in the fluidized bed reduction of titanomagnetite are systematically studied in this paper. Pre-oxidation treatment of titanomagnetite can significantly lower the critical stable reduction fluidization gas velocity to 0.17 m/s, which is reduced by 56% compared to that of titanomagnetite reduction without pre-oxidation, while achieving a metallization degree of >90%, Corresponding to the different reduction fluidization behaviors, three pre-oxidation operation regions have been divided, taking oxidation degrees of 26% and 86% as the boundaries. Focusing on the particle surface morphology evolution in the pre-oxidation–reduction process, the relationship between the surface morphology of pre-oxidized ore and the reduced iron with fluidization properties is built. The improving method of pre-oxidation on the reduction fluidization provides a novel approach to prevent defluidization by particle surface modification, especially for the fluidized bed reduction of poly-metallic iron ore.
The direct reduction process is an important development direction of low-carbon ironmaking and efficient comprehensive utilization of poly-metallic iron ore, such as titanomagnetite. However, the defluidization of reduced iron particles with a high metallization degree at a high temperature will seriously affect the operation of fluidized bed reduction. Coupling the pre-oxidation enhancing reduction and the particle surface modification of titanomagnetite, the behavior and mechanism of pre-oxidation improvement on fluidization in the fluidized bed reduction of titanomagnetite are systematically studied in this paper. Pre-oxidation treatment of titanomagnetite can significantly lower the critical stable reduction fluidization gas velocity to 0.17 m/s, which is reduced by 56% compared to that of titanomagnetite reduction without pre-oxidation, while achieving a metallization degree of >90%, Corresponding to the different reduction fluidization behaviors, three pre-oxidation operation regions have been divided, taking oxidation degrees of 26% and 86% as the boundaries. Focusing on the particle surface morphology evolution in the pre-oxidation–reduction process, the relationship between the surface morphology of pre-oxidized ore and the reduced iron with fluidization properties is built. The improving method of pre-oxidation on the reduction fluidization provides a novel approach to prevent defluidization by particle surface modification, especially for the fluidized bed reduction of poly-metallic iron ore.
, Available online 19 March 2024,
https://doi.org/10.1007/s12613-024-2885-9
Abstract:
Using aeolian sand (AS) for goaf backfilling allows coordination of green mining and AS control. Cemented AS backfill (CASB) exhibits brittle fracture. Polypropylene (PP) fibers are good toughening materials. When the toughening effect of fibers is analyzed, their influence on the slurry conveying performance should also be considered. Additionally, cement affects the interactions among the hydration products, fibers, and aggregates. In this study, the effects of cement content (8wt%, 9wt%, and 10wt%) and PP fiber length (6, 9, and 12 mm) and dosage (0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, and 0.25wt%) on fluidity and mechanical properties of the fiber-toughened CASB (FCASB) were analyzed. The results indicated that with increases in the three aforementioned factors, the slump flow decreased, while the rheological parameters increased. Uniaxial compressive strength (UCS) increased with the increase of cement content and fiber length, and with an increase in fiber dosage, it first increased and then decreased. The strain increased with the increase of fiber dosage and length. The effect of PP fibers became more pronounced with the increase of cement content. Digital image correlation (DIC) test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure, and reduce the stress concentration of the FCASB. Scanning electron microscopy (SEM) test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers. On the basis of single-factor analysis, the response surface method (RSM) was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS. The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established. In conclusion, the response law of the FCASB properties under the effects of cement and PP fibers were obtained, which provides theoretical and engineering guidance for FCASB filling.
Using aeolian sand (AS) for goaf backfilling allows coordination of green mining and AS control. Cemented AS backfill (CASB) exhibits brittle fracture. Polypropylene (PP) fibers are good toughening materials. When the toughening effect of fibers is analyzed, their influence on the slurry conveying performance should also be considered. Additionally, cement affects the interactions among the hydration products, fibers, and aggregates. In this study, the effects of cement content (8wt%, 9wt%, and 10wt%) and PP fiber length (6, 9, and 12 mm) and dosage (0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, and 0.25wt%) on fluidity and mechanical properties of the fiber-toughened CASB (FCASB) were analyzed. The results indicated that with increases in the three aforementioned factors, the slump flow decreased, while the rheological parameters increased. Uniaxial compressive strength (UCS) increased with the increase of cement content and fiber length, and with an increase in fiber dosage, it first increased and then decreased. The strain increased with the increase of fiber dosage and length. The effect of PP fibers became more pronounced with the increase of cement content. Digital image correlation (DIC) test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure, and reduce the stress concentration of the FCASB. Scanning electron microscopy (SEM) test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers. On the basis of single-factor analysis, the response surface method (RSM) was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS. The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established. In conclusion, the response law of the FCASB properties under the effects of cement and PP fibers were obtained, which provides theoretical and engineering guidance for FCASB filling.
, Available online 27 February 2024,
https://doi.org/10.1007/s12613-024-2866-z
Abstract:
Graphitized spent carbon cathode (SCC) is a hazardous solid waste generated in the aluminum electrolysis process. In this study, a flotation–acid leaching process is proposed for the purification of graphitized SCC, and the use of the purified SCC as an anode material for lithium-ion batteries is explored. The flotation and acid leaching processes were separately optimized through one-way experiments. The maximum SCC carbon content (93wt%) was achieved at a 90% proportion of −200-mesh flotation particle size, a slurry concentration of 10wt%, a rotation speed of 1600 r/min, and an inflatable capacity of 0.2 m3/h (referred to as FSCC). In the subsequent acid leaching process, the SCC carbon content reached 99.58wt% at a leaching concentration of 5 mol/L, a leaching time of 100 min, a leaching temperature of 85°C, and an HCl/FSCC volume ratio of 5:1. The purified graphitized SCC (referred to as FSCC-CL) was utilized as an anode material, and it exhibited an initial capacity of 348.2 mAh/g at 0.1 C and a reversible capacity of 347.8 mAh/g after 100 cycles. Moreover, compared with commercial graphite, FSCC-CL exhibited better reversibility and cycle stability. Thus, purified SCC is an important candidate for anode material, and the flotation–acid leaching purification method is suitable for the resourceful recycling of SCC.
Graphitized spent carbon cathode (SCC) is a hazardous solid waste generated in the aluminum electrolysis process. In this study, a flotation–acid leaching process is proposed for the purification of graphitized SCC, and the use of the purified SCC as an anode material for lithium-ion batteries is explored. The flotation and acid leaching processes were separately optimized through one-way experiments. The maximum SCC carbon content (93wt%) was achieved at a 90% proportion of −200-mesh flotation particle size, a slurry concentration of 10wt%, a rotation speed of 1600 r/min, and an inflatable capacity of 0.2 m3/h (referred to as FSCC). In the subsequent acid leaching process, the SCC carbon content reached 99.58wt% at a leaching concentration of 5 mol/L, a leaching time of 100 min, a leaching temperature of 85°C, and an HCl/FSCC volume ratio of 5:1. The purified graphitized SCC (referred to as FSCC-CL) was utilized as an anode material, and it exhibited an initial capacity of 348.2 mAh/g at 0.1 C and a reversible capacity of 347.8 mAh/g after 100 cycles. Moreover, compared with commercial graphite, FSCC-CL exhibited better reversibility and cycle stability. Thus, purified SCC is an important candidate for anode material, and the flotation–acid leaching purification method is suitable for the resourceful recycling of SCC.
, Available online 23 February 2024,
https://doi.org/10.1007/s12613-024-2858-z
Abstract:
Advanced processes for peroxymonosulfate (PMS)-based oxidation are efficient in eliminating toxic and refractory organic pollutants from sewage. The activation of electron-withdrawing H\begin{document}$ {\mathrm{S}\mathrm{O}}_{5}^{-} $\end{document} \begin{document}$ {\text{·}\mathrm{S}\mathrm{O}}_{4}^{-} $\end{document} \begin{document}$ \text{·}\mathrm{O}\mathrm{H} $\end{document} \begin{document}$ {\text{·}\mathrm{O}}_{2}^{-} $\end{document}
Advanced processes for peroxymonosulfate (PMS)-based oxidation are efficient in eliminating toxic and refractory organic pollutants from sewage. The activation of electron-withdrawing H
, Available online 27 December 2023,
https://doi.org/10.1007/s12613-023-2819-y
Abstract:
Pyrolusite comprises the foremost manganese oxides and is a major source of manganese production. An innovative hydrogen-based mineral phase transformation technology to pyrolusite was proposed, where a 96.44% distribution rate of divalent manganese (Mn2+) was observed at an optimal roasting temperature of 650°C, a roasting time of 25 min, and an H2 concentration of 20vol%; under these conditions. The manganese predominantly existed in the form of manganosite. This study investigated the generation mechanism of manganosite based on the reduction kinetics, phase transformation, and structural evolution of pyrolusite and revealed that high temperature improved the distribution rate, and the optimal kinetic model for the reaction was the random nucleation and growth model (reaction order, n = 3/2) with an activation energy (Ea) of 24.119 kJ·mol−1. Throughout the mineral phase transformation, manganese oxide from the outer layer of particles moves inward to the core. In addition, pyrolusite follows the reduction sequence of MnO2 → Mn2O3 → Mn3O4 → MnO, and the reduction of manganese oxides in each valence state simultaneously proceeds. These findings provide significant insight into the efficient and clean utilization of pyrolusite.
Pyrolusite comprises the foremost manganese oxides and is a major source of manganese production. An innovative hydrogen-based mineral phase transformation technology to pyrolusite was proposed, where a 96.44% distribution rate of divalent manganese (Mn2+) was observed at an optimal roasting temperature of 650°C, a roasting time of 25 min, and an H2 concentration of 20vol%; under these conditions. The manganese predominantly existed in the form of manganosite. This study investigated the generation mechanism of manganosite based on the reduction kinetics, phase transformation, and structural evolution of pyrolusite and revealed that high temperature improved the distribution rate, and the optimal kinetic model for the reaction was the random nucleation and growth model (reaction order, n = 3/2) with an activation energy (Ea) of 24.119 kJ·mol−1. Throughout the mineral phase transformation, manganese oxide from the outer layer of particles moves inward to the core. In addition, pyrolusite follows the reduction sequence of MnO2 → Mn2O3 → Mn3O4 → MnO, and the reduction of manganese oxides in each valence state simultaneously proceeds. These findings provide significant insight into the efficient and clean utilization of pyrolusite.
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