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, Available online 19 April 2024,
https://doi.org/10.1007/s12613-024-2919-3
Abstract:
The effects of deformation temperature on the transformation-induced plasticity (TRIP)-aided 304L, twinning-induced plasticity (TWIP)-assisted 316L, and highly alloyed stable 904L austenitic stainless steels were compared for the first time to tune the mechanical properties, strengthening mechanisms, and strength-ductility synergy. For this purpose, the scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), X-ray diffraction (XRD), tensile testing, work-hardening analysis, and thermodynamics calculations were used. The induced plasticity effects led to a high temperature-dependency of work-hardening behavior in the 304L and 316L stainless steels. As the deformation temperature increased, the metastable 304L stainless steel showed the sequence of TRIP, TWIP, and weakening of the induced plasticity mechanism; while the disappearance of the TWIP effect in the 316L stainless steel was also observed. However, the solid-solution strengthening in the 904L superaustenitic stainless steel maintained the tensile properties over a wide temperature range, surpassing the performance of 304L and 316L stainless steels. In this regard, the dependency of the total elongation on the deformation temperature was less pronounced for the 904L alloy due to the absence of additional plasticity mechanisms. These results revealed the importance of solid-solution strengthening and the associated high friction stress for superior mechanical behavior over a wide temperature range.
The effects of deformation temperature on the transformation-induced plasticity (TRIP)-aided 304L, twinning-induced plasticity (TWIP)-assisted 316L, and highly alloyed stable 904L austenitic stainless steels were compared for the first time to tune the mechanical properties, strengthening mechanisms, and strength-ductility synergy. For this purpose, the scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), X-ray diffraction (XRD), tensile testing, work-hardening analysis, and thermodynamics calculations were used. The induced plasticity effects led to a high temperature-dependency of work-hardening behavior in the 304L and 316L stainless steels. As the deformation temperature increased, the metastable 304L stainless steel showed the sequence of TRIP, TWIP, and weakening of the induced plasticity mechanism; while the disappearance of the TWIP effect in the 316L stainless steel was also observed. However, the solid-solution strengthening in the 904L superaustenitic stainless steel maintained the tensile properties over a wide temperature range, surpassing the performance of 304L and 316L stainless steels. In this regard, the dependency of the total elongation on the deformation temperature was less pronounced for the 904L alloy due to the absence of additional plasticity mechanisms. These results revealed the importance of solid-solution strengthening and the associated high friction stress for superior mechanical behavior over a wide temperature range.
, Available online 13 March 2024,
https://doi.org/10.1007/s12613-024-2880-1
Abstract:
NiMZn/C@melamine sponge–derived carbon (MSDC) composites (M = Co, Fe, and Mn) were prepared by a vacuum pumping solution method followed by carbonization. A large number of carbon nanotubes (CNTs) homogeneously attached to the surfaces of the three-dimensional cross-linked of the sponge–derived carbon in the NiCoZn/C@MSDC composite, and CNTs were detected in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. Ni3ZnC0.7, Ni3Fe, and MnO in-situ formed in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. The CNTs in the NiCoZn/C@MSDC composite efficiently modulated its complex permittivity. Thus, the composite exhibited the best performance among the composites, with the minimum reflection loss (RLmin) of −33.1 dB at 18 GHz and thickness of 1.4 mm. The bandwidth for RL of ≤−10 dB was up to 5.04 GHz at the thickness of 1.7 mm and loading of 25wt%. The optimized impedance matching, enhanced interfacial and dipole polarization, remarkable conduction loss, and multiple reflections and scattering of the incident microwaves improved the microwave absorption performance. The effects of Co, Ni, and Fe on the phase and morphology provided an alternative way for developing highly efficient and broadband microwave absorbers.
NiMZn/C@melamine sponge–derived carbon (MSDC) composites (M = Co, Fe, and Mn) were prepared by a vacuum pumping solution method followed by carbonization. A large number of carbon nanotubes (CNTs) homogeneously attached to the surfaces of the three-dimensional cross-linked of the sponge–derived carbon in the NiCoZn/C@MSDC composite, and CNTs were detected in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. Ni3ZnC0.7, Ni3Fe, and MnO in-situ formed in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. The CNTs in the NiCoZn/C@MSDC composite efficiently modulated its complex permittivity. Thus, the composite exhibited the best performance among the composites, with the minimum reflection loss (RLmin) of −33.1 dB at 18 GHz and thickness of 1.4 mm. The bandwidth for RL of ≤−10 dB was up to 5.04 GHz at the thickness of 1.7 mm and loading of 25wt%. The optimized impedance matching, enhanced interfacial and dipole polarization, remarkable conduction loss, and multiple reflections and scattering of the incident microwaves improved the microwave absorption performance. The effects of Co, Ni, and Fe on the phase and morphology provided an alternative way for developing highly efficient and broadband microwave absorbers.
, Available online 9 March 2024,
https://doi.org/10.1007/s12613-024-2879-7
Abstract:
To increase the processability and plasticity of the selective laser melting (SLM) fabricated Al–Mn–Mg–Er–Zr alloys, a novel TiB2-modified Al–Mn–Mg–Er–Zr alloy with a mixture of Al–Mn–Mg–Er–Zr and nano-TiB2 powders was fabricated by SLM. The processability, microstructure, and mechanical properties of the alloy were systematically investigated by density measurement, microstructure characterization, and mechanical properties testing. The alloys fabricated at 250 W displayed higher relative densities due to a uniformly smooth top surface and appropriate laser energy input. The maximum relative density value of the alloy reached 99.7%±0.1%, demonstrating good processability. The alloy exhibited a duplex grain microstructure consisting of columnar regions primarily and equiaxed regions with TiB2, Al6Mn, and Al3Er phases distributed along the grain boundaries. After directly aging treatment at a high temperature of 400°C, the strength of the SLM-fabricated TiB2/Al–Mn–Mg–Er–Zr alloy increased due to the precipitation of the secondary Al6Mn phases. The maximum yield strength and ultimate tensile strength of the aging alloy were measured to be (374 ± 1) and (512 ± 13) MPa, respectively. The SLM-fabricated TiB2/Al–Mn–Mg–Er–Zr alloy demonstrates exceptional strength and thermal stability due to the synergistic effects of the inhibition of grain growth, the incorporation of TiB2 nanoparticles, and the precipitation of secondary Al6Mn nanoparticles.
To increase the processability and plasticity of the selective laser melting (SLM) fabricated Al–Mn–Mg–Er–Zr alloys, a novel TiB2-modified Al–Mn–Mg–Er–Zr alloy with a mixture of Al–Mn–Mg–Er–Zr and nano-TiB2 powders was fabricated by SLM. The processability, microstructure, and mechanical properties of the alloy were systematically investigated by density measurement, microstructure characterization, and mechanical properties testing. The alloys fabricated at 250 W displayed higher relative densities due to a uniformly smooth top surface and appropriate laser energy input. The maximum relative density value of the alloy reached 99.7%±0.1%, demonstrating good processability. The alloy exhibited a duplex grain microstructure consisting of columnar regions primarily and equiaxed regions with TiB2, Al6Mn, and Al3Er phases distributed along the grain boundaries. After directly aging treatment at a high temperature of 400°C, the strength of the SLM-fabricated TiB2/Al–Mn–Mg–Er–Zr alloy increased due to the precipitation of the secondary Al6Mn phases. The maximum yield strength and ultimate tensile strength of the aging alloy were measured to be (374 ± 1) and (512 ± 13) MPa, respectively. The SLM-fabricated TiB2/Al–Mn–Mg–Er–Zr alloy demonstrates exceptional strength and thermal stability due to the synergistic effects of the inhibition of grain growth, the incorporation of TiB2 nanoparticles, and the precipitation of secondary Al6Mn nanoparticles.
, Available online 7 March 2024,
https://doi.org/10.1007/s12613-024-2872-1
Abstract:
To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), 10mol% Ta5+ doped in the B site of strontium ferrite perovskite oxide (SrTa0.1Fe0.9O3–δ, STF) is investigated and optimized. The effects of Ta5+ doping on structure, transition metal reduction, oxygen nonstoichiometry, thermal expansion, and electrical performance are evaluated systematically. Via 10mol% Ta5+ doping, the thermal expansion coefficient (TEC) decreased from 34.1 × 10–6 (SrFeO3–δ) to 14.6 × 10–6 K–1 (STF), which is near the TEC of electrolyte (13.3 × 10–6 K–1 for Sm0.2Ce0.8O1.9, SDC), indicates excellent thermomechanical compatibility. At 550–750°C, STF shows superior oxygen vacancy concentrations (0.262 to 0.331), which is critical in the oxygen-reduction reaction (ORR). Oxygen temperature-programmed desorption (O2-TPD) indicated the thermal reduction onset temperature of iron ion is around 420°C, which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves. At 600°C, the STF electrode shows area-specific resistance (ASR) of 0.152 Ω·cm2 and peak power density (PPD) of 749 mW·cm–2. ORR activity of STF was further improved by introducing 30wt% Sm0.2Ce0.8O1.9 (SDC) powder, STF+SDC composite cathode achieving outstanding ASR value of 0.115 Ω·cm2 at 600°C, even comparable with benchmark cobalt-containing cathode, Ba0.5Sr0.5Co0.8Fe0.2O3–δ (BSCF). Distribution of relaxation time (DRT) analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode. At 650°C, STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm–2. The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.
To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), 10mol% Ta5+ doped in the B site of strontium ferrite perovskite oxide (SrTa0.1Fe0.9O3–δ, STF) is investigated and optimized. The effects of Ta5+ doping on structure, transition metal reduction, oxygen nonstoichiometry, thermal expansion, and electrical performance are evaluated systematically. Via 10mol% Ta5+ doping, the thermal expansion coefficient (TEC) decreased from 34.1 × 10–6 (SrFeO3–δ) to 14.6 × 10–6 K–1 (STF), which is near the TEC of electrolyte (13.3 × 10–6 K–1 for Sm0.2Ce0.8O1.9, SDC), indicates excellent thermomechanical compatibility. At 550–750°C, STF shows superior oxygen vacancy concentrations (0.262 to 0.331), which is critical in the oxygen-reduction reaction (ORR). Oxygen temperature-programmed desorption (O2-TPD) indicated the thermal reduction onset temperature of iron ion is around 420°C, which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves. At 600°C, the STF electrode shows area-specific resistance (ASR) of 0.152 Ω·cm2 and peak power density (PPD) of 749 mW·cm–2. ORR activity of STF was further improved by introducing 30wt% Sm0.2Ce0.8O1.9 (SDC) powder, STF+SDC composite cathode achieving outstanding ASR value of 0.115 Ω·cm2 at 600°C, even comparable with benchmark cobalt-containing cathode, Ba0.5Sr0.5Co0.8Fe0.2O3–δ (BSCF). Distribution of relaxation time (DRT) analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode. At 650°C, STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm–2. The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.
, Available online 7 March 2024,
https://doi.org/10.1007/s12613-024-2876-x
Abstract:
To enhance the long-term corrosion resistance of the plasma electrolytic oxidation (PEO) coating on the magnesium (Mg) alloy, an inorganic salt combined with corrosion inhibitors was used for posttreatment of the coating. In this study, the corrosion performance of PEO-coated AM50 Mg was significantly improved by loading sodium lauryl sulfonate (SDS) and sodium dodecyl benzene sulfonate into Ba(NO3)2 post-sealing solutions. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectrometer, and Ultraviolet–visible analyses showed that the inhibitors enhanced the incorporation of BaO2 into PEO coatings. Electrochemical impedance showed that post-sealing in Ba(NO3)2/SDS treatment enhanced corrosion resistance by three orders of magnitude. The total impedance value remained at 926 Ω·cm² after immersing in a 0.5wt% NaCl solution for 768 h. A salt spray test for 40 days did not show any obvious region of corrosion, proving excellent post-sealing by Ba(NO3)2/SDS treatment. The corrosion resistance of the coating was enhanced through the synergistic effect of BaO2 pore sealing and SDS adsorption.
To enhance the long-term corrosion resistance of the plasma electrolytic oxidation (PEO) coating on the magnesium (Mg) alloy, an inorganic salt combined with corrosion inhibitors was used for posttreatment of the coating. In this study, the corrosion performance of PEO-coated AM50 Mg was significantly improved by loading sodium lauryl sulfonate (SDS) and sodium dodecyl benzene sulfonate into Ba(NO3)2 post-sealing solutions. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectrometer, and Ultraviolet–visible analyses showed that the inhibitors enhanced the incorporation of BaO2 into PEO coatings. Electrochemical impedance showed that post-sealing in Ba(NO3)2/SDS treatment enhanced corrosion resistance by three orders of magnitude. The total impedance value remained at 926 Ω·cm² after immersing in a 0.5wt% NaCl solution for 768 h. A salt spray test for 40 days did not show any obvious region of corrosion, proving excellent post-sealing by Ba(NO3)2/SDS treatment. The corrosion resistance of the coating was enhanced through the synergistic effect of BaO2 pore sealing and SDS adsorption.
, Available online 23 February 2024,
https://doi.org/10.1007/s12613-024-2861-4
Abstract:
The precipitation of Fe3O4 particles and the accompanied formation of Fe3O4-wrapped copper structure are the main obstacles to copper recovery from the molten slag during the pyrometallurgical smelting of copper concentrates. Herein, the commercial powdery pyrite or anthracite is replaced with pyrite–anthracite pellets as the reductants to remove a large amount of Fe3O4 particles in the molten slag, resulting in a deep fracture in the Fe3O4-wrapped copper microstructure and the full exposure of the copper matte cores. When 1wt% composite pellet is used as the reductant, the copper matte droplets are enlarged greatly from 25 μm to a size observable by the naked eye, with the copper content being enriched remarkably from 1.2wt% to 4.5wt%. Density functional theory calculation results imply that the formation of the Fe3O4-wrapped copper structure is due to the preferential adhesion of Cu2S on the Fe3O4 particles. X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer (FTIR), and Raman spectroscopy results all reveal that the high-efficiency conversion of Fe3O4 to FeO can decrease the volume fraction of the solid phase and promote the depolymerization of silicate network structure. As a consequence, the settling of copper matte droplets is enhanced due to the lowered slag viscosity, contributing to the high efficiency of copper–slag separation for copper recovery. The results provide new insights into the enhanced in-situ enrichment of copper from molten slag.
The precipitation of Fe3O4 particles and the accompanied formation of Fe3O4-wrapped copper structure are the main obstacles to copper recovery from the molten slag during the pyrometallurgical smelting of copper concentrates. Herein, the commercial powdery pyrite or anthracite is replaced with pyrite–anthracite pellets as the reductants to remove a large amount of Fe3O4 particles in the molten slag, resulting in a deep fracture in the Fe3O4-wrapped copper microstructure and the full exposure of the copper matte cores. When 1wt% composite pellet is used as the reductant, the copper matte droplets are enlarged greatly from 25 μm to a size observable by the naked eye, with the copper content being enriched remarkably from 1.2wt% to 4.5wt%. Density functional theory calculation results imply that the formation of the Fe3O4-wrapped copper structure is due to the preferential adhesion of Cu2S on the Fe3O4 particles. X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer (FTIR), and Raman spectroscopy results all reveal that the high-efficiency conversion of Fe3O4 to FeO can decrease the volume fraction of the solid phase and promote the depolymerization of silicate network structure. As a consequence, the settling of copper matte droplets is enhanced due to the lowered slag viscosity, contributing to the high efficiency of copper–slag separation for copper recovery. The results provide new insights into the enhanced in-situ enrichment of copper from molten slag.
, Available online 19 February 2024,
https://doi.org/10.1007/s12613-024-2852-5
Abstract:
In the present work, plastic deformation mechanisms were initially tailored by adjusting the deformation temperature in the range of 0 to 200°C in AISI 304L austenitic stainless steel, aiming to optimize the strength-ductility synergy. It was shown that the combined twinning-induced plasticity (TWIP)/transformation-induced plasticity (TRIP) effects and a wider strain range for the TRIP effect up to higher strains by adjusting the deformation temperature are good strategies to improve the strength-ductility synergy of this metastable stainless steel. In this regard, by consideration of the observed temperature-dependency of plastic deformation, the controlled sequence of TWIP and TRIP effects for archiving superior strength-ductility trade-off was intended by the pre-designed temperature jump tensile tests. Accordingly, the optimum tensile toughness of 846 MJ/m3 and total elongation to 133% were obtained by this strategy via exploiting the advantages of the TWIP effect at 100°C and the TRIP effect at 25°C at the later stages of the straining. Consequently, a deformation-temperature-transformation (DTT) diagram was developed for this metastable alloy. Moreover, based on work-hardening analysis, it was found that the main phenomenon constraining further improvement in the ductility and strengthening was the yielding of the deformation-induced α'-martensite.
In the present work, plastic deformation mechanisms were initially tailored by adjusting the deformation temperature in the range of 0 to 200°C in AISI 304L austenitic stainless steel, aiming to optimize the strength-ductility synergy. It was shown that the combined twinning-induced plasticity (TWIP)/transformation-induced plasticity (TRIP) effects and a wider strain range for the TRIP effect up to higher strains by adjusting the deformation temperature are good strategies to improve the strength-ductility synergy of this metastable stainless steel. In this regard, by consideration of the observed temperature-dependency of plastic deformation, the controlled sequence of TWIP and TRIP effects for archiving superior strength-ductility trade-off was intended by the pre-designed temperature jump tensile tests. Accordingly, the optimum tensile toughness of 846 MJ/m3 and total elongation to 133% were obtained by this strategy via exploiting the advantages of the TWIP effect at 100°C and the TRIP effect at 25°C at the later stages of the straining. Consequently, a deformation-temperature-transformation (DTT) diagram was developed for this metastable alloy. Moreover, based on work-hardening analysis, it was found that the main phenomenon constraining further improvement in the ductility and strengthening was the yielding of the deformation-induced α'-martensite.
, Available online 6 February 2024,
https://doi.org/10.1007/s12613-024-2845-4
Abstract:
The efficient recycling of vanadium from converter vanadium-bearing slag is highly significant for sustainable development and circular economy. The key to developing novel processes and improving traditional routes lies in the thermodynamic data. In this study, the equilibrium phase relations for the Fe2O3–TiO2–V2O5 system at 1200°C in air were investigated using a high-temperature equilibrium-quenching technique, followed by analysis using scanning electron microscopy-energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy. One liquid-phase region, two two-phase regions (liquid–rutile and liquid–ferropseudobrookite), and one three-phase region (liquid–rutile–ferropseudobrookite) were determined. The variation in the TiO2 and V2O5 contents with the Fe2O3 content was examined for rutile and ferropseudobrookite solid solutions. However, on further comparison with the predictions of FactSage 8.1, significant discrepancies were identified, highlighting that greater attention must be paid to updating the current thermodynamic database related to vanadium-bearing slag systems.
The efficient recycling of vanadium from converter vanadium-bearing slag is highly significant for sustainable development and circular economy. The key to developing novel processes and improving traditional routes lies in the thermodynamic data. In this study, the equilibrium phase relations for the Fe2O3–TiO2–V2O5 system at 1200°C in air were investigated using a high-temperature equilibrium-quenching technique, followed by analysis using scanning electron microscopy-energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy. One liquid-phase region, two two-phase regions (liquid–rutile and liquid–ferropseudobrookite), and one three-phase region (liquid–rutile–ferropseudobrookite) were determined. The variation in the TiO2 and V2O5 contents with the Fe2O3 content was examined for rutile and ferropseudobrookite solid solutions. However, on further comparison with the predictions of FactSage 8.1, significant discrepancies were identified, highlighting that greater attention must be paid to updating the current thermodynamic database related to vanadium-bearing slag systems.
, Available online 6 February 2024,
https://doi.org/10.1007/s12613-024-2848-1
Abstract:
To enhance the Young’s modulus (E) and strength of titanium alloys, we designed titanium matrix composites with interconnected microstructure based on the Hashin–Shtrikman theory. According to the results, the in-situ reaction yielded an interconnected microstructure composed of Ti2C particles when the Ti2C content reached 50vol%. With widths of 10 and 230 nm, the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti2C particles. The composites with interconnected microstructure attained superior properties, including E of 174.3 GPa and ultimate flexural strength of 1014 GPa. Compared with that of pure Ti, the E of the composite was increased by 55% due to the high Ti2C content and interconnected microstructure. The outstanding strength resulted from the strong interfacial bonding, load-bearing capacity of interconnected Ti2C particles, and bimodal intraparticle Ti lamellae, which minimized the average crack driving force. Interrupted flexural tests revealed preferential crack initiation along the {001} cleavage plane and grain boundary of Ti2C in the region with the highest tensile stress. In addition, the propagation can be efficiently inhibited by interparticle Ti grains, which prevented the brittle fracture of the composites.
To enhance the Young’s modulus (E) and strength of titanium alloys, we designed titanium matrix composites with interconnected microstructure based on the Hashin–Shtrikman theory. According to the results, the in-situ reaction yielded an interconnected microstructure composed of Ti2C particles when the Ti2C content reached 50vol%. With widths of 10 and 230 nm, the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti2C particles. The composites with interconnected microstructure attained superior properties, including E of 174.3 GPa and ultimate flexural strength of 1014 GPa. Compared with that of pure Ti, the E of the composite was increased by 55% due to the high Ti2C content and interconnected microstructure. The outstanding strength resulted from the strong interfacial bonding, load-bearing capacity of interconnected Ti2C particles, and bimodal intraparticle Ti lamellae, which minimized the average crack driving force. Interrupted flexural tests revealed preferential crack initiation along the {001} cleavage plane and grain boundary of Ti2C in the region with the highest tensile stress. In addition, the propagation can be efficiently inhibited by interparticle Ti grains, which prevented the brittle fracture of the composites.
, Available online 19 January 2024,
https://doi.org/10.1007/s12613-024-2837-4
Abstract:
Electric arc furnace (EAF) dust is an important secondary resource containing metals, such as zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduce environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this issue, a facile approach that involves oxygen-assisted chlorination using molten MgCl2 is proposed. This work focused on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively broke down the ZnFe2O4 structure, and the high O2 atmosphere considerably promoted the separation of Zn from other components in the form of ZnCl2. The presence of O2 facilitated the formation of MgFe2O4, which stabilized Fe and prevented its chlorination. Furthermore, the excessive use of MgCl2 resulted in increased evaporation loss, and high temperatures promoted the rapid separation of Zn. Building on these findings, we successfully extracted ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination. Under optimized conditions, this method achieved exceptional Zn chlorination percentage of over 97% within a short period, while Fe chlorination remained below 1%. The resulting volatiles contained 85wt% of ZnCl2, which can be further processed to produce metallic Zn. The findings offer guidance for the selective recovery of valuable metals, particularly from solid wastes such as EAF dust.
Electric arc furnace (EAF) dust is an important secondary resource containing metals, such as zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduce environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this issue, a facile approach that involves oxygen-assisted chlorination using molten MgCl2 is proposed. This work focused on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively broke down the ZnFe2O4 structure, and the high O2 atmosphere considerably promoted the separation of Zn from other components in the form of ZnCl2. The presence of O2 facilitated the formation of MgFe2O4, which stabilized Fe and prevented its chlorination. Furthermore, the excessive use of MgCl2 resulted in increased evaporation loss, and high temperatures promoted the rapid separation of Zn. Building on these findings, we successfully extracted ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination. Under optimized conditions, this method achieved exceptional Zn chlorination percentage of over 97% within a short period, while Fe chlorination remained below 1%. The resulting volatiles contained 85wt% of ZnCl2, which can be further processed to produce metallic Zn. The findings offer guidance for the selective recovery of valuable metals, particularly from solid wastes such as EAF dust.
, Available online 17 January 2024,
https://doi.org/10.1007/s12613-024-2834-7
Abstract:
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, Available online 16 January 2024,
https://doi.org/10.1007/s12613-024-2829-4
Abstract:
A novel method was developed to enhance the utilization rate of steel slag (SS). Through treatment of SS with phosphoric acid and aminopropyl triethoxysilane (KH550), we obtained modified SS (MSS), which was used to replace talcum powder (TP) in the preparation of MSS/wood–plastic composites (MSS/WPCs). The composites were fabricated through melting blending and hot pressing. Their mechanical and combustion properties, which comprise heat release, smoke release, and thermal stability, were systematically investigated. MSS can improve the mechanical strength of the composites through grafting reactions between wood powder and thermoplastics. Notably, MSS/WPC#50 (16wt% MSS) with an MSS-to-TP mass ratio of 1:1 exhibited optimal comprehensive performance. Compared with those of WPC#0 without MSS, the tensile, flexural, and impact strengths of MSS/WPC#50 were increased by 18.5%, 12.8%, and 18.0%, respectively. Moreover, the MSS/WPC#50 sample achieved the highest limited oxygen index of 22.5%, the highest vertical burning rating at the V-1 level, and the lowest horizontal burning rate at 44.2 mm/min. The formation of a dense and stable char layer led to improved thermal stability and a considerable reduction in heat and smoke release of MSS/WPC#50. However, the partial replacement of TP with MSS slightly compromised the mechanical and flame-retardant properties, possibly due to the weak grafting caused by SS powder agglomeration. These findings suggest the suitability of MSS/WPCs for high-value-added applications as decorative panels indoors or outdoors.
A novel method was developed to enhance the utilization rate of steel slag (SS). Through treatment of SS with phosphoric acid and aminopropyl triethoxysilane (KH550), we obtained modified SS (MSS), which was used to replace talcum powder (TP) in the preparation of MSS/wood–plastic composites (MSS/WPCs). The composites were fabricated through melting blending and hot pressing. Their mechanical and combustion properties, which comprise heat release, smoke release, and thermal stability, were systematically investigated. MSS can improve the mechanical strength of the composites through grafting reactions between wood powder and thermoplastics. Notably, MSS/WPC#50 (16wt% MSS) with an MSS-to-TP mass ratio of 1:1 exhibited optimal comprehensive performance. Compared with those of WPC#0 without MSS, the tensile, flexural, and impact strengths of MSS/WPC#50 were increased by 18.5%, 12.8%, and 18.0%, respectively. Moreover, the MSS/WPC#50 sample achieved the highest limited oxygen index of 22.5%, the highest vertical burning rating at the V-1 level, and the lowest horizontal burning rate at 44.2 mm/min. The formation of a dense and stable char layer led to improved thermal stability and a considerable reduction in heat and smoke release of MSS/WPC#50. However, the partial replacement of TP with MSS slightly compromised the mechanical and flame-retardant properties, possibly due to the weak grafting caused by SS powder agglomeration. These findings suggest the suitability of MSS/WPCs for high-value-added applications as decorative panels indoors or outdoors.
, Available online 12 January 2024,
https://doi.org/10.1007/s12613-024-2826-7
Abstract:
Slurry electrolysis (SE), as a hydrometallurgical process, has the characteristic of a multitank series connection, which leads to various stirring conditions and a complex solid suspension state. The computational fluid dynamics (CFD), which requires high computing resources, and a combination with machine learning was proposed to construct a rapid prediction model for the liquid flow and solid concentration fields in a SE tank. Through scientific selection of calculation samples via orthogonal experiments, a comprehensive dataset covering a wide range of conditions was established while effectively reducing the number of simulations and providing reasonable weights for each factor. Then, a prediction model of the SE tank was constructed using the K-nearest neighbor algorithm. The results show that with the increase in levels of orthogonal experiments, the prediction accuracy of the model improved remarkably. The model established with four factors and nine levels can accurately predict the flow and concentration fields, and the regression coefficients of average velocity and solid concentration were 0.926 and 0.937, respectively. Compared with traditional CFD, the response time of field information prediction in this model was reduced from 75 h to 20 s, which solves the problem of serious lag in CFD applied alone to actual production and meets real-time production control requirements.
Slurry electrolysis (SE), as a hydrometallurgical process, has the characteristic of a multitank series connection, which leads to various stirring conditions and a complex solid suspension state. The computational fluid dynamics (CFD), which requires high computing resources, and a combination with machine learning was proposed to construct a rapid prediction model for the liquid flow and solid concentration fields in a SE tank. Through scientific selection of calculation samples via orthogonal experiments, a comprehensive dataset covering a wide range of conditions was established while effectively reducing the number of simulations and providing reasonable weights for each factor. Then, a prediction model of the SE tank was constructed using the K-nearest neighbor algorithm. The results show that with the increase in levels of orthogonal experiments, the prediction accuracy of the model improved remarkably. The model established with four factors and nine levels can accurately predict the flow and concentration fields, and the regression coefficients of average velocity and solid concentration were 0.926 and 0.937, respectively. Compared with traditional CFD, the response time of field information prediction in this model was reduced from 75 h to 20 s, which solves the problem of serious lag in CFD applied alone to actual production and meets real-time production control requirements.
, Available online 3 January 2024,
https://doi.org/10.1007/s12613-024-2825-8
Abstract:
The substantial arsenic (As) content present in arsenic-containing bio-leaching residue (ABR) presents noteworthy environmental challenges attributable to its inherent instability and susceptibility to leaching. Given its elevated calcium sulfate content, ABR exhibits considerable promise for industrial applications. This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement (SSC), offering an innovative binder for cemented paste backfill (CPB). Thermal treatment at varying temperatures of 150, 350, 600, and 800°C was employed to modify ABR’s performance. The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR. Subsequently, the hydration characteristics of SSC utilizing ABR, with or without thermal treatment, were studied, encompassing reaction kinetics, setting time, strength development, and microstructure. The findings revealed that thermal treatment changed the calcium sulfate structure in ABR, consequently impacting the resultant sample performance. Notably, calcination at 600°C demonstrated optimal modification effects on both early and long-term strength attributes. This enhanced performance can be attributed to the augmented formation of reaction products and a densified microstructure. Furthermore, the thermal treatment elicited modifications in the chemical As fractions within ABR, with limited impact on the As immobilization capacity of the prepared binders.
The substantial arsenic (As) content present in arsenic-containing bio-leaching residue (ABR) presents noteworthy environmental challenges attributable to its inherent instability and susceptibility to leaching. Given its elevated calcium sulfate content, ABR exhibits considerable promise for industrial applications. This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement (SSC), offering an innovative binder for cemented paste backfill (CPB). Thermal treatment at varying temperatures of 150, 350, 600, and 800°C was employed to modify ABR’s performance. The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR. Subsequently, the hydration characteristics of SSC utilizing ABR, with or without thermal treatment, were studied, encompassing reaction kinetics, setting time, strength development, and microstructure. The findings revealed that thermal treatment changed the calcium sulfate structure in ABR, consequently impacting the resultant sample performance. Notably, calcination at 600°C demonstrated optimal modification effects on both early and long-term strength attributes. This enhanced performance can be attributed to the augmented formation of reaction products and a densified microstructure. Furthermore, the thermal treatment elicited modifications in the chemical As fractions within ABR, with limited impact on the As immobilization capacity of the prepared binders.
, Available online 27 December 2023,
https://doi.org/10.1007/s12613-023-2814-3
Abstract:
The toxic cyanides in cyanide residues produced from cyanidation process for gold extraction are harmful to the environment. Pyrite is one of the main minerals existing in cyanide residues. In this work, the interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue were analyzed. Results revealed that high pH value, high cyanide concentration, and high pyrite dosage promoted the interaction of cyanide with pyrite. The cyanidation of pyrite was pseudo-second-order with respect to cyanide. The decyanation of pyrite cyanide residue by Na2SO3/air oxidation was performed. The cyanide removal efficiency was 83.9% after 1 h of reaction time under the optimal conditions of pH value of 11.2,\begin{document}$ {\mathrm{S}\mathrm{O}}_{3}^{2-} $\end{document} \begin{document}$ \mathrm{F}\mathrm{e}{\left(\mathrm{C}\mathrm{N}\right)}_{6}^{4-} $\end{document}
The toxic cyanides in cyanide residues produced from cyanidation process for gold extraction are harmful to the environment. Pyrite is one of the main minerals existing in cyanide residues. In this work, the interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue were analyzed. Results revealed that high pH value, high cyanide concentration, and high pyrite dosage promoted the interaction of cyanide with pyrite. The cyanidation of pyrite was pseudo-second-order with respect to cyanide. The decyanation of pyrite cyanide residue by Na2SO3/air oxidation was performed. The cyanide removal efficiency was 83.9% after 1 h of reaction time under the optimal conditions of pH value of 11.2,
, Available online 27 December 2023,
https://doi.org/10.1007/s12613-023-2815-2
Abstract:
As a cornerstone of the national economy, the iron and steel industry generates a significant amount of sintering dust containing both valuable lead resources and deleterious elements. Flotation is a promising technique for lead recovery from sintering dust, but efficient separation from Fe2O3 is still challenging. This study investigated the cooperative effect of sodium lauryl sulfate (SLS, C12H25SO4Na) and sodium pyrophosphate (SPP, Na4P2O7) on the selective flotation of lead oxide minerals (PbOHCl and PbSO4) from hematite (Fe2O3). Optimal flotation conditions were first identified, resulting in high recovery of lead oxide minerals while inhibiting Fe2O3 flotation. Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR) analysis, adsorption capacity analysis, and X-ray photoelectron spectroscopy (XPS) studies offer insights into the adsorption behaviors of the reagents on mineral surfaces, revealing strong adsorption of SLS on PbOHCl and PbSO4 surfaces and remarkable adsorption of SPP on Fe2O3. The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior, highlighting the pivotal role of reagent adsorption in the separation process. These findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery, paving the way for sustainable resource management in the iron and steel industry.
As a cornerstone of the national economy, the iron and steel industry generates a significant amount of sintering dust containing both valuable lead resources and deleterious elements. Flotation is a promising technique for lead recovery from sintering dust, but efficient separation from Fe2O3 is still challenging. This study investigated the cooperative effect of sodium lauryl sulfate (SLS, C12H25SO4Na) and sodium pyrophosphate (SPP, Na4P2O7) on the selective flotation of lead oxide minerals (PbOHCl and PbSO4) from hematite (Fe2O3). Optimal flotation conditions were first identified, resulting in high recovery of lead oxide minerals while inhibiting Fe2O3 flotation. Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR) analysis, adsorption capacity analysis, and X-ray photoelectron spectroscopy (XPS) studies offer insights into the adsorption behaviors of the reagents on mineral surfaces, revealing strong adsorption of SLS on PbOHCl and PbSO4 surfaces and remarkable adsorption of SPP on Fe2O3. The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior, highlighting the pivotal role of reagent adsorption in the separation process. These findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery, paving the way for sustainable resource management in the iron and steel industry.
, Available online 15 December 2023,
https://doi.org/10.1007/s12613-023-2812-5
Abstract:
The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature. To address these problems, a multi-micro-alloyed high-plasticity Mg–1.8Zn–0.8Gd–0.1Ca–0.2Mn (wt%) alloy was developed using the unique role of rare earth and Ca solute atoms. In addition, the influence of the annealing process on the grain size, second phase, texture, and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity magnesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters. The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content: there are small amounts of larger-sized block and long string phases along the rolling direction, as well as several spherical and rodlike particle phases inside the grains. With increasing annealing temperature, the grain size decreases and then increases, and the morphology, number, and size of the second phase also change correspondingly. The particle phase within the grains vanishes at 450°C, and the grain size increases sharply. In the full recrystallization stage at 300–350°C, the optimum strength–plasticity comprehensive mechanical properties are presented, with yield strengths of 182.1 and 176.9 MPa, tensile strengths of 271.1 and 275.8 MPa in the RD and TD, and elongation values of 27.4% and 32.3%, respectively. Moreover, there are still some larger-sized phases in the alloy that influence its mechanical properties, which offers room for improvement.
The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature. To address these problems, a multi-micro-alloyed high-plasticity Mg–1.8Zn–0.8Gd–0.1Ca–0.2Mn (wt%) alloy was developed using the unique role of rare earth and Ca solute atoms. In addition, the influence of the annealing process on the grain size, second phase, texture, and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity magnesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters. The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content: there are small amounts of larger-sized block and long string phases along the rolling direction, as well as several spherical and rodlike particle phases inside the grains. With increasing annealing temperature, the grain size decreases and then increases, and the morphology, number, and size of the second phase also change correspondingly. The particle phase within the grains vanishes at 450°C, and the grain size increases sharply. In the full recrystallization stage at 300–350°C, the optimum strength–plasticity comprehensive mechanical properties are presented, with yield strengths of 182.1 and 176.9 MPa, tensile strengths of 271.1 and 275.8 MPa in the RD and TD, and elongation values of 27.4% and 32.3%, respectively. Moreover, there are still some larger-sized phases in the alloy that influence its mechanical properties, which offers room for improvement.
, Available online 1 December 2023,
https://doi.org/10.1007/s12613-023-2797-0
Abstract:
Magnesium (Mg) alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility. However, they suffer from low corrosion resistance and antibacterial activity. In this research, semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium (MgO@GNS/Mg) composite to improve mechanical, corrosion and cytocompatibility characteristics. Investigations have revealed that the incorporation of MgO@GNS nanohybrids into Mg-based composite enhanced microhardness and compressive strength. In vitro, osteoblast cell culture tests show that using MgO@GNS nanohybrid fillers enhances osteoblast adhesion and apatite mineralization. The presence of MgO@GNS nanoparticles in the composites decreased the opening defects, micro-cracks and micro-pores of the composites thus preventing the penetration of the corrosive solution into the matrix. Studies demonstrated that the MgO@GNS/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid bilayer. Therefore, the MgO@GNS/Mg composite with high mechanical strength, antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.
Magnesium (Mg) alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility. However, they suffer from low corrosion resistance and antibacterial activity. In this research, semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium (MgO@GNS/Mg) composite to improve mechanical, corrosion and cytocompatibility characteristics. Investigations have revealed that the incorporation of MgO@GNS nanohybrids into Mg-based composite enhanced microhardness and compressive strength. In vitro, osteoblast cell culture tests show that using MgO@GNS nanohybrid fillers enhances osteoblast adhesion and apatite mineralization. The presence of MgO@GNS nanoparticles in the composites decreased the opening defects, micro-cracks and micro-pores of the composites thus preventing the penetration of the corrosive solution into the matrix. Studies demonstrated that the MgO@GNS/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid bilayer. Therefore, the MgO@GNS/Mg composite with high mechanical strength, antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.
, Available online 25 November 2023,
https://doi.org/10.1007/s12613-023-2793-4
Abstract:
Malachite is a common copper oxide mineral that is often enriched using the sulfidization–xanthate flotation method. Currently, the direct sulfidization method cannot yield copper concentrate products. Therefore, a new sulfidization flotation process was developed to promote the efficient recovery of malachite. In this study, Cu2+ was used as an activator to interact with the sample surface and increase its reaction sites, thereby strengthening the mineral sulfidization process and reactivity. Compared to single copper ion activation, the flotation effect of malachite significantly increased after stepwise Cu2+ activation. Zeta potential, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF–SIMS), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS), and atomic force microscopy (AFM) analysis results indicated that the adsorption of S species was significantly enhanced on the mineral surface due to the increase in active Cu sites after Cu2+ stepwise activation. Meanwhile, the proportion of active Cu–S species also increased, further improving the reaction between the sample surface and subsequent collectors. Fourier-transform infrared spectroscopy (FT-IR) and contact angle tests implied that the xanthate species were easily and stably adsorbed onto the mineral surface after Cu2+ stepwise activation, thereby improving the hydrophobicity of the mineral surface. Therefore, the copper sites on the malachite surface after Cu2+ stepwise activation promote the reactivity of the mineral surface and enhance sulfidization flotation of malachite.
Malachite is a common copper oxide mineral that is often enriched using the sulfidization–xanthate flotation method. Currently, the direct sulfidization method cannot yield copper concentrate products. Therefore, a new sulfidization flotation process was developed to promote the efficient recovery of malachite. In this study, Cu2+ was used as an activator to interact with the sample surface and increase its reaction sites, thereby strengthening the mineral sulfidization process and reactivity. Compared to single copper ion activation, the flotation effect of malachite significantly increased after stepwise Cu2+ activation. Zeta potential, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF–SIMS), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS), and atomic force microscopy (AFM) analysis results indicated that the adsorption of S species was significantly enhanced on the mineral surface due to the increase in active Cu sites after Cu2+ stepwise activation. Meanwhile, the proportion of active Cu–S species also increased, further improving the reaction between the sample surface and subsequent collectors. Fourier-transform infrared spectroscopy (FT-IR) and contact angle tests implied that the xanthate species were easily and stably adsorbed onto the mineral surface after Cu2+ stepwise activation, thereby improving the hydrophobicity of the mineral surface. Therefore, the copper sites on the malachite surface after Cu2+ stepwise activation promote the reactivity of the mineral surface and enhance sulfidization flotation of malachite.
, Available online 21 November 2023,
https://doi.org/10.1007/s12613-023-2790-7
Abstract:
Inhibitors are important for flotation separation of quartz and feldspar. In this study, a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp. Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments. And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism. The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca2+ and SS in sequence under the optimal proportion of 1:5. A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired, and was found to be 90.70wt% and 83.70%, respectively. It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared (FT-IR) and adsorption capacity tests. The results of X-ray photoelectron spectroscopy (XPS) indicated that Ca2+ directly interacts with the surface of quartz to increase the adsorption of collectors. In contrast, the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na+ and Ca2+ taking the place of K+, resulting in the composite inhibitor forms a hydrophilic structure, which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site. The combination of Ca2+ and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector, thus achieving the effect of efficient separation. A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.
Inhibitors are important for flotation separation of quartz and feldspar. In this study, a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp. Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments. And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism. The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca2+ and SS in sequence under the optimal proportion of 1:5. A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired, and was found to be 90.70wt% and 83.70%, respectively. It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared (FT-IR) and adsorption capacity tests. The results of X-ray photoelectron spectroscopy (XPS) indicated that Ca2+ directly interacts with the surface of quartz to increase the adsorption of collectors. In contrast, the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na+ and Ca2+ taking the place of K+, resulting in the composite inhibitor forms a hydrophilic structure, which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site. The combination of Ca2+ and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector, thus achieving the effect of efficient separation. A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.
, Available online 10 November 2023,
https://doi.org/10.1007/s12613-023-2784-5
Abstract:
With the continuous development of mineral resources to high altitude areas, the study of sulfide ore flotation in unconventional systems has been emphasized. There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation, but the specific suitable dissolved oxygen value is inconclusive, and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude. In this paper, we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N2/O2 and dissolved oxygen under atmospheric conditions. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), Fourier transform infrared spectrometer (FT-IR), UV-vis spectrophotometer, zeta potential, and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude (4600 m dissolved oxygen (DO) = 4.0 mg/L). The results of pure mineral flotation indicated that the high altitude and low dissolved oxygen environment is favorable for pyrite flotation. Contact angle measurements and XPS analysis showed that the high altitude atmosphere slows down the oxidation of pyrite surface, facilitates\begin{document}${\rm S}_n^{2-} $\end{document}
With the continuous development of mineral resources to high altitude areas, the study of sulfide ore flotation in unconventional systems has been emphasized. There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation, but the specific suitable dissolved oxygen value is inconclusive, and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude. In this paper, we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N2/O2 and dissolved oxygen under atmospheric conditions. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), Fourier transform infrared spectrometer (FT-IR), UV-vis spectrophotometer, zeta potential, and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude (4600 m dissolved oxygen (DO) = 4.0 mg/L). The results of pure mineral flotation indicated that the high altitude and low dissolved oxygen environment is favorable for pyrite flotation. Contact angle measurements and XPS analysis showed that the high altitude atmosphere slows down the oxidation of pyrite surface, facilitates
, Available online 10 November 2023,
https://doi.org/10.1007/s12613-023-2778-3
Abstract:
Resin-bonded Al–SiC composite was sintered at 1100, 1300, and 1500°C in the air, the oxidation mechanism was investigated. The reaction models were also established. The oxidation resistance of the Al–SiC composite was significantly enhanced with temperature increase. SiC in the exterior of the composite was partially oxidized slightly, while the transformation of metastable Al4C3 to stable Al4SiC4 existed in the interior. At 1100°C, Al in the interior reacted with residual C to form Al4C3. With increasing to 1300°C, high temperature and low oxygen partial pressure lead to active oxidation of SiC, and internal gas composition transforms to Al2O(g) + CO(g) + SiO(g) as the reaction proceeds. After Al4C3 is formed, CO(g) and SiO(g) are continuously deposited on its surface, transforming to Al4SiC4. At 1500°C, a dense layer consisting of SiC and Al4SiC4 whiskers is formed which cuts off the diffusion channel of oxygen. The active oxidation of SiC is accelerated, enabling more gas to participate in the synthesis of Al4SiC4, eventually forming hexagonal lamellar Al4SiC4 with mutual accumulation between SiC particles. Introducing Al enhances the oxidation resistance of SiC. In addition, the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.
Resin-bonded Al–SiC composite was sintered at 1100, 1300, and 1500°C in the air, the oxidation mechanism was investigated. The reaction models were also established. The oxidation resistance of the Al–SiC composite was significantly enhanced with temperature increase. SiC in the exterior of the composite was partially oxidized slightly, while the transformation of metastable Al4C3 to stable Al4SiC4 existed in the interior. At 1100°C, Al in the interior reacted with residual C to form Al4C3. With increasing to 1300°C, high temperature and low oxygen partial pressure lead to active oxidation of SiC, and internal gas composition transforms to Al2O(g) + CO(g) + SiO(g) as the reaction proceeds. After Al4C3 is formed, CO(g) and SiO(g) are continuously deposited on its surface, transforming to Al4SiC4. At 1500°C, a dense layer consisting of SiC and Al4SiC4 whiskers is formed which cuts off the diffusion channel of oxygen. The active oxidation of SiC is accelerated, enabling more gas to participate in the synthesis of Al4SiC4, eventually forming hexagonal lamellar Al4SiC4 with mutual accumulation between SiC particles. Introducing Al enhances the oxidation resistance of SiC. In addition, the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.
, Available online 30 January 2024,
https://doi.org/10.1007/s12613-024-2842-7
Abstract:
The combination of electrospinning and hot pressing, namely the electrospinning-hot pressing technique (EHPT), is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance. The emerging composite membrane prepared by EHPT, which exhibits the advantages of large surface area, controllable morphology, and compact structure, has attracted immense attention. In this paper, the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed. Moreover, the state-of-the-art applications of composite membranes in these two fields are introduced. In particular, in the field of thermal energy storage, EHPT-prepared membranes have longitudinal and transverse nanofibers, which generate unique thermal conductivity pathways; also, these nanofibers offer enough space for the filling of functional materials. Moreover, EHPT-prepared membranes are beneficial in thermal management systems, building energy conservation, and electrical energy storage, e.g., improving the electrochemical properties of the separators as well as their mechanical and thermal stability. The application of electrospinning-hot pressing membranes on capacitors, lithium-ion batteries (LIBs), fuel cells, sodium-ion batteries (SIBs), and hydrogen bromine flow batteries (HBFBs) still requires examination. In the future, EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.
The combination of electrospinning and hot pressing, namely the electrospinning-hot pressing technique (EHPT), is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance. The emerging composite membrane prepared by EHPT, which exhibits the advantages of large surface area, controllable morphology, and compact structure, has attracted immense attention. In this paper, the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed. Moreover, the state-of-the-art applications of composite membranes in these two fields are introduced. In particular, in the field of thermal energy storage, EHPT-prepared membranes have longitudinal and transverse nanofibers, which generate unique thermal conductivity pathways; also, these nanofibers offer enough space for the filling of functional materials. Moreover, EHPT-prepared membranes are beneficial in thermal management systems, building energy conservation, and electrical energy storage, e.g., improving the electrochemical properties of the separators as well as their mechanical and thermal stability. The application of electrospinning-hot pressing membranes on capacitors, lithium-ion batteries (LIBs), fuel cells, sodium-ion batteries (SIBs), and hydrogen bromine flow batteries (HBFBs) still requires examination. In the future, EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.
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