Search2023 Vol. 30, No. 5
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2023, vol. 30, no. 5, pp.
791-801.
https://doi.org/10.1007/s12613-022-2528-y
Abstract:
High geostress will become a normality in the deep because in-situ stress rises linearly with depth. The geological structure grows immensely intricate as depth increases. Faults, small fractures, and joint fissures are widely developed. The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism. Hydrofracturing tests were conducted in seven deep boreholes. We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall, footwall, between faults, end of faults, junction of faults, and far-field of faults. The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes. The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation, which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress. Due to regional tectonics and faulting, the magnitude, direction, and stress regime are all extremely different. The concentration degree of geostress and direction change will vary with the location of faults near faults, but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults. The focal mechanism solution has been verified using historical seismic ground motion vectors. The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position. Changes in stress differentiation and its ratio from strong to weak occur between faults, intersection, footwall, end of faults, and hanging wall; along with the sequence of orientation is the footwall, between faults, the end of faults, intersection, and hanging wall. This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.
High geostress will become a normality in the deep because in-situ stress rises linearly with depth. The geological structure grows immensely intricate as depth increases. Faults, small fractures, and joint fissures are widely developed. The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism. Hydrofracturing tests were conducted in seven deep boreholes. We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall, footwall, between faults, end of faults, junction of faults, and far-field of faults. The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes. The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation, which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress. Due to regional tectonics and faulting, the magnitude, direction, and stress regime are all extremely different. The concentration degree of geostress and direction change will vary with the location of faults near faults, but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults. The focal mechanism solution has been verified using historical seismic ground motion vectors. The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position. Changes in stress differentiation and its ratio from strong to weak occur between faults, intersection, footwall, end of faults, and hanging wall; along with the sequence of orientation is the footwall, between faults, the end of faults, intersection, and hanging wall. This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.
2023, vol. 30, no. 5, pp.
802-812.
https://doi.org/10.1007/s12613-022-2554-9
Abstract:
To ensure safe and economical backfill mining, the mechanical response of the backfill–rock interaction system needs to be understood. The numerical investigation of the mechanical behavior of backfill–rock composite structure (BRCS) under triaxial compression, which includes deformation, failure patterns, strength characteristics, and acoustic emission (AE) evolution, was proposed. The models used in the tests have one rough interface, two cement–iron tailings ratios (CTRs), four interface angles (IAs), and three confining pressures (CPs). Results showed that the deformation, strength characteristics, and failure patterns of BRCS under triaxial compression depend on IA, CP, and CTR. The stress–strain curves of BRCS under triaxial compression could be divided into five stages, namely, compaction, elasticity, yield, strain softening, and residual stress. The relevant AE counts have corresponding relationships with different stages. The triaxial compressive strengths of composites increase linearly with the increase of the CP. Furthermore, the CP stress strengthening effect occurs. When the IAs are 45° and 60°, the failure areas of composites appear in the interface and backfill. When the IAs are 75° and 90°, the failure areas of composites appear in the backfill, interface, and rock. Moreover, the corresponding failure modes yield the combined shear failure. The research results provide the basis for further understanding of the stability of the BRCS.
To ensure safe and economical backfill mining, the mechanical response of the backfill–rock interaction system needs to be understood. The numerical investigation of the mechanical behavior of backfill–rock composite structure (BRCS) under triaxial compression, which includes deformation, failure patterns, strength characteristics, and acoustic emission (AE) evolution, was proposed. The models used in the tests have one rough interface, two cement–iron tailings ratios (CTRs), four interface angles (IAs), and three confining pressures (CPs). Results showed that the deformation, strength characteristics, and failure patterns of BRCS under triaxial compression depend on IA, CP, and CTR. The stress–strain curves of BRCS under triaxial compression could be divided into five stages, namely, compaction, elasticity, yield, strain softening, and residual stress. The relevant AE counts have corresponding relationships with different stages. The triaxial compressive strengths of composites increase linearly with the increase of the CP. Furthermore, the CP stress strengthening effect occurs. When the IAs are 45° and 60°, the failure areas of composites appear in the interface and backfill. When the IAs are 75° and 90°, the failure areas of composites appear in the backfill, interface, and rock. Moreover, the corresponding failure modes yield the combined shear failure. The research results provide the basis for further understanding of the stability of the BRCS.
2023, vol. 30, no. 5, pp.
813-823.
https://doi.org/10.1007/s12613-022-2522-4
Abstract:
This study presents a comparative study of the flocculation behavior of kaolinite induced by chitosan-graft-poly(acrylamide-dimethyl diallyl ammonium chloride) (Chi-g-CPAM) and a commercial cationic polyacrylamide (CPAM). The flocculation behaviour was characterised in terms of both flocculation kinetics and the corresponding morphology changes during flocculation. Both Chi-g-CPAM and CPAM were grafted from silica wafers by means of atom transfer radical polymerization (ATRP). The quartz crystal microbalance with dissipation (QCM-D) tests were conducted. The equilibrium time flocculated by Chi-g-CPAM was found to be 0.46 times as that of CPAM, together with a larger total mass of kaolinite layer. The flocculation behaviour by Chi-g-CPAM can be well captured by a pseudo-first-order model. In contrast, the presence of CPAM leads to a more complex kinetics. A relatively larger fitting slope (0.4663) was obtained at the initial stage but the fitting slope droped to 0.2026 after 800 min, indicating a densification process caused by CPAM. The flocculation kinetics of CPAM can be captured by the Elovich model for the inital stage but the combination of pseudo-first-order and pseudo-second-order models for the latter stages, which can be attributed to the long chain of CPAM. With a dosage of 75 g/t, the settling test with Chi-g-CPAM exhibits the same turbidity in the supernatant but a smaller layer thickness of the settlement compared to CPAM. The study enables a better understanding of the flocculation behavior and contributes to the development of efficient flocculants in mineral processing and tailings treatment.
This study presents a comparative study of the flocculation behavior of kaolinite induced by chitosan-graft-poly(acrylamide-dimethyl diallyl ammonium chloride) (Chi-g-CPAM) and a commercial cationic polyacrylamide (CPAM). The flocculation behaviour was characterised in terms of both flocculation kinetics and the corresponding morphology changes during flocculation. Both Chi-g-CPAM and CPAM were grafted from silica wafers by means of atom transfer radical polymerization (ATRP). The quartz crystal microbalance with dissipation (QCM-D) tests were conducted. The equilibrium time flocculated by Chi-g-CPAM was found to be 0.46 times as that of CPAM, together with a larger total mass of kaolinite layer. The flocculation behaviour by Chi-g-CPAM can be well captured by a pseudo-first-order model. In contrast, the presence of CPAM leads to a more complex kinetics. A relatively larger fitting slope (0.4663) was obtained at the initial stage but the fitting slope droped to 0.2026 after 800 min, indicating a densification process caused by CPAM. The flocculation kinetics of CPAM can be captured by the Elovich model for the inital stage but the combination of pseudo-first-order and pseudo-second-order models for the latter stages, which can be attributed to the long chain of CPAM. With a dosage of 75 g/t, the settling test with Chi-g-CPAM exhibits the same turbidity in the supernatant but a smaller layer thickness of the settlement compared to CPAM. The study enables a better understanding of the flocculation behavior and contributes to the development of efficient flocculants in mineral processing and tailings treatment.
2023, vol. 30, no. 5, pp.
824-833.
https://doi.org/10.1007/s12613-022-2523-3
Abstract:
In order to develop limonite and decrease CO2 emissions, siderite is proposed as a clean reductant for suspension magnetization roasting (SMR) of limonite. An iron concentrate (iron grade: 65.92wt%, iron recovery: 98.54wt%) was obtained by magnetic separation under the optimum SMR conditions: siderite dosage 40wt%, roasting temperature 700°C, roasting time 10 min. According to the magnetic analysis, SMR achieved the conversion of weak magnetic minerals to strong magnetic minerals, thus enabling the recovery of iron via magnetic separation. Based on the phase transformation analysis, during the SMR process, limonite was first dehydrated and converted to hematite, and then siderite decomposed to generate magnetite and CO, where CO reduced the freshly formed hematite to magnetite. The microstructure evolution analysis indicated that the magnetite particles were loose and porous with a destroyed structure, making them easier to be ground. The non-isothermal kinetic results show that the main reaction between limonite and siderite conformed to the two-dimension diffusion mechanism, suggesting that the diffusion of CO controlled the reaction. These results encourage the application of siderite as a reductant in SMR.
In order to develop limonite and decrease CO2 emissions, siderite is proposed as a clean reductant for suspension magnetization roasting (SMR) of limonite. An iron concentrate (iron grade: 65.92wt%, iron recovery: 98.54wt%) was obtained by magnetic separation under the optimum SMR conditions: siderite dosage 40wt%, roasting temperature 700°C, roasting time 10 min. According to the magnetic analysis, SMR achieved the conversion of weak magnetic minerals to strong magnetic minerals, thus enabling the recovery of iron via magnetic separation. Based on the phase transformation analysis, during the SMR process, limonite was first dehydrated and converted to hematite, and then siderite decomposed to generate magnetite and CO, where CO reduced the freshly formed hematite to magnetite. The microstructure evolution analysis indicated that the magnetite particles were loose and porous with a destroyed structure, making them easier to be ground. The non-isothermal kinetic results show that the main reaction between limonite and siderite conformed to the two-dimension diffusion mechanism, suggesting that the diffusion of CO controlled the reaction. These results encourage the application of siderite as a reductant in SMR.
2023, vol. 30, no. 5, pp.
834-843.
https://doi.org/10.1007/s12613-022-2564-7
Abstract:
The formation mechanism of calcium vanadate and manganese vanadate and the difference between calcium and manganese in the reaction with vanadium are basic issues in the calcification roasting and manganese roasting process with vanadium slag. In this work, CaO–V2O5 and MnO2–V2O5 diffusion couples were prepared and roasted for different time periods to illustrate and compare the diffusion reaction mechanisms. Then, the changes in the diffusion product and diffusion coefficient were investigated and calculated based on scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis. Results show that with the extension of the roasting time, the diffusion reaction gradually proceeds among the CaO–V2O5 and MnO2–V2O5 diffusion couples. The regional boundaries of calcium and vanadium are easily identifiable for the CaO–V2O5 diffusion couple. Meanwhile, for the MnO2–V2O5 diffusion couple, MnO2 gradually decomposes to form Mn2O3, and vanadium diffuses into the interior of Mn2O3. Only a part of vanadium combines with manganese to form the diffusion production layer. CaV2O6 and MnV2O6 are the interfacial reaction products of the CaO–V2O5 and MnO2–V2O5 diffusion couples, respectively, whose thicknesses are 39.85 and 32.13 μm when roasted for 16 h. After 16 h, both diffusion couples reach the reaction equilibrium due to the limitation of diffusion. The diffusion coefficient of the CaO–V2O5 diffusion couple is higher than that of the MnO2–V2O5 diffusion couple for the same roasting time, and the diffusion reaction between vanadium and calcium is easier than that between vanadium and manganese.
The formation mechanism of calcium vanadate and manganese vanadate and the difference between calcium and manganese in the reaction with vanadium are basic issues in the calcification roasting and manganese roasting process with vanadium slag. In this work, CaO–V2O5 and MnO2–V2O5 diffusion couples were prepared and roasted for different time periods to illustrate and compare the diffusion reaction mechanisms. Then, the changes in the diffusion product and diffusion coefficient were investigated and calculated based on scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis. Results show that with the extension of the roasting time, the diffusion reaction gradually proceeds among the CaO–V2O5 and MnO2–V2O5 diffusion couples. The regional boundaries of calcium and vanadium are easily identifiable for the CaO–V2O5 diffusion couple. Meanwhile, for the MnO2–V2O5 diffusion couple, MnO2 gradually decomposes to form Mn2O3, and vanadium diffuses into the interior of Mn2O3. Only a part of vanadium combines with manganese to form the diffusion production layer. CaV2O6 and MnV2O6 are the interfacial reaction products of the CaO–V2O5 and MnO2–V2O5 diffusion couples, respectively, whose thicknesses are 39.85 and 32.13 μm when roasted for 16 h. After 16 h, both diffusion couples reach the reaction equilibrium due to the limitation of diffusion. The diffusion coefficient of the CaO–V2O5 diffusion couple is higher than that of the MnO2–V2O5 diffusion couple for the same roasting time, and the diffusion reaction between vanadium and calcium is easier than that between vanadium and manganese.
2023, vol. 30, no. 5, pp.
844-856.
https://doi.org/10.1007/s12613-022-2558-5
Abstract:
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow, circulation flow rate, and mixing time during Ruhrstahl-Heraeus (RH) refining process. Also, a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up, and measurements were carried out to validate the mathematical model. The results show that, with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min–1, the mixing time predicted by the mathematical model agrees well with the measured values. The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations, where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value. In addition, the circulation flow rate was 9 kg·s–1. When the gas blowing nozzle was horizontally rotated by either 30° or 45°, the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle, due to the rotational flow formed in the up-snorkel. Furthermore, the mixing time at the monitoring point 1, 2, and 3 was shortened by around 21.3%, 28.2%, and 12.3%, respectively. With the nozzle angle of 30° and 45°, the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow, circulation flow rate, and mixing time during Ruhrstahl-Heraeus (RH) refining process. Also, a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up, and measurements were carried out to validate the mathematical model. The results show that, with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min–1, the mixing time predicted by the mathematical model agrees well with the measured values. The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations, where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value. In addition, the circulation flow rate was 9 kg·s–1. When the gas blowing nozzle was horizontally rotated by either 30° or 45°, the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle, due to the rotational flow formed in the up-snorkel. Furthermore, the mixing time at the monitoring point 1, 2, and 3 was shortened by around 21.3%, 28.2%, and 12.3%, respectively. With the nozzle angle of 30° and 45°, the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
2023, vol. 30, no. 5, pp.
857-867.
https://doi.org/10.1007/s12613-022-2436-1
Abstract:
Currently, the process of extracting rubidium from ores has attracted a great deal of attention due to the increasing application of rubidium in high-technology field. A novel process for the comprehensive utilization of rubidium ore resources is proposed in this paper. The process consists mainly of mineral dissociation, selective leaching, and desilication. The results showed that the stable silicon–oxygen tetrahedral structure of the rubidium ore was completely disrupted by thermal activation and the mineral was completely dissociated, which was conducive to subsequent selective leaching. Under the optimal conditions, extractions of 98.67% Rb and 96.23% K were obtained by leaching the rubidium ore. Moreover, the addition of a certain amount of activated Al(OH)3 during leaching can effectively inhibit the leaching of silicon. In the meantime, the leach residue was sodalite, which was successfully synthesized to zeolite A by hydrothermal conversion. The proposed process provided a feasible strategy for the green extraction of rubidium and the sustainable utilization of various resources.
Currently, the process of extracting rubidium from ores has attracted a great deal of attention due to the increasing application of rubidium in high-technology field. A novel process for the comprehensive utilization of rubidium ore resources is proposed in this paper. The process consists mainly of mineral dissociation, selective leaching, and desilication. The results showed that the stable silicon–oxygen tetrahedral structure of the rubidium ore was completely disrupted by thermal activation and the mineral was completely dissociated, which was conducive to subsequent selective leaching. Under the optimal conditions, extractions of 98.67% Rb and 96.23% K were obtained by leaching the rubidium ore. Moreover, the addition of a certain amount of activated Al(OH)3 during leaching can effectively inhibit the leaching of silicon. In the meantime, the leach residue was sodalite, which was successfully synthesized to zeolite A by hydrothermal conversion. The proposed process provided a feasible strategy for the green extraction of rubidium and the sustainable utilization of various resources.
2023, vol. 30, no. 5, pp.
868-876.
https://doi.org/10.1007/s12613-022-2527-z
Abstract:
The effects of fluoride ions (F−) on the electrochemical behavior and coordination properties of titanium ions (Tin+) were studied in this work, by combining electrochemical and mathematical analysis as well as spectral techniques. The α was taken as a factor to indicate the molar concentration ratio of F− and Tin+. Cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential method (OCP) were used to study the electrochemical behavior of titanium ions under conditions of various α, and in-situ sampler was used to prepare molten salt samples when α equal to 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 8.0. And then, samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results showed that F− in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable. Ti2+ cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state. Investigation revealed that the mechanism behind those phenomenon is the coordination compounds (\begin{document}$\text{TiCl}_{j}\text{F}_{i}^{m-}$\end{document} ![]()
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The effects of fluoride ions (F−) on the electrochemical behavior and coordination properties of titanium ions (Tin+) were studied in this work, by combining electrochemical and mathematical analysis as well as spectral techniques. The α was taken as a factor to indicate the molar concentration ratio of F− and Tin+. Cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential method (OCP) were used to study the electrochemical behavior of titanium ions under conditions of various α, and in-situ sampler was used to prepare molten salt samples when α equal to 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 8.0. And then, samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results showed that F− in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable. Ti2+ cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state. Investigation revealed that the mechanism behind those phenomenon is the coordination compounds (
2023, vol. 30, no. 5, pp.
877-885.
https://doi.org/10.1007/s12613-022-2492-6
Abstract:
Platinum group metals (PGMs), especially Pd, Pt, and Rh, have drawn great attention due to their unique features. Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors. This work investigates the effect of various parameters including the acidity, extractant concentration, phase ratio A/O, and diluents on the Pd and Pt extraction and their stripping behaviors. The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothio-Cyanex 272 and trioctylamine (TOA). Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd, and only one single stage is needed to recover more than 99.9% of Pd, leaving behind all the Pt, Rh, and base metals of Fe, Mg, Ce, Ni, Cu, and Co in the raffinate. The loaded Pd is efficiently stripped by acidic thiourea solutions. TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L–1 HCl. More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction. Diluted HCl easily scrubs the loaded base metals (Fe, Cu, and Co). The loaded Pt is efficiently stripped by 1.0 mol·L–1 thiourea and 0.05–0.1 mol·L–1 NaOH solutions. Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.
Platinum group metals (PGMs), especially Pd, Pt, and Rh, have drawn great attention due to their unique features. Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors. This work investigates the effect of various parameters including the acidity, extractant concentration, phase ratio A/O, and diluents on the Pd and Pt extraction and their stripping behaviors. The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothio-Cyanex 272 and trioctylamine (TOA). Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd, and only one single stage is needed to recover more than 99.9% of Pd, leaving behind all the Pt, Rh, and base metals of Fe, Mg, Ce, Ni, Cu, and Co in the raffinate. The loaded Pd is efficiently stripped by acidic thiourea solutions. TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L–1 HCl. More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction. Diluted HCl easily scrubs the loaded base metals (Fe, Cu, and Co). The loaded Pt is efficiently stripped by 1.0 mol·L–1 thiourea and 0.05–0.1 mol·L–1 NaOH solutions. Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.
2023, vol. 30, no. 5, pp.
886-896.
https://doi.org/10.1007/s12613-022-2569-2
Abstract:
The metallurgical properties of the CaO–SiO2–Al2O3–4.6wt%MgO–Fe2O3 slag system, formed by the co-treatment process of spent automotive catalyst (SAC) and copper-bearing electroplating sludge (CBES), were studied systematically in this paper. The slag structure, melting temperature, and viscous characteristics were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, FactSage calculation, and viscosity measurements. Experimental results show that the increase of Fe2O3 content (3.8wt%–16.6wt%), the mass ratio of CaO/SiO2 (m(CaO)/m(SiO2), 0.5–1.3), and the mass ratio of SiO2/Al2O3 (m(SiO2)/m(Al2O3), 1.0–5.0) can promote the depolymerization of silicate network, and the presence of a large amount of Fe2O3 in form of tetrahedral and octahedral units ensures the charge compensation of Al3+ ions and makes Al2O3 only behave as an acid oxide. Thermodynamic calculation and viscosity measurements show that with the increase of Fe2O3 content, m(CaO)/m(SiO2), and m(SiO2)/m(Al2O3), the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag, leading to the decrease in melting point and viscosity of the slag, while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point. Based on experimental analysis, the preferred slag composition with low polymerization degree, viscosity, and melting point is as follows: Fe2O3 content of 10.2wt%–13.4wt%, m(CaO)/m(SiO2) of 0.7–0.9 and m(SiO2)/m(Al2O3) of 3.0–4.0. This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.
The metallurgical properties of the CaO–SiO2–Al2O3–4.6wt%MgO–Fe2O3 slag system, formed by the co-treatment process of spent automotive catalyst (SAC) and copper-bearing electroplating sludge (CBES), were studied systematically in this paper. The slag structure, melting temperature, and viscous characteristics were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, FactSage calculation, and viscosity measurements. Experimental results show that the increase of Fe2O3 content (3.8wt%–16.6wt%), the mass ratio of CaO/SiO2 (m(CaO)/m(SiO2), 0.5–1.3), and the mass ratio of SiO2/Al2O3 (m(SiO2)/m(Al2O3), 1.0–5.0) can promote the depolymerization of silicate network, and the presence of a large amount of Fe2O3 in form of tetrahedral and octahedral units ensures the charge compensation of Al3+ ions and makes Al2O3 only behave as an acid oxide. Thermodynamic calculation and viscosity measurements show that with the increase of Fe2O3 content, m(CaO)/m(SiO2), and m(SiO2)/m(Al2O3), the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag, leading to the decrease in melting point and viscosity of the slag, while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point. Based on experimental analysis, the preferred slag composition with low polymerization degree, viscosity, and melting point is as follows: Fe2O3 content of 10.2wt%–13.4wt%, m(CaO)/m(SiO2) of 0.7–0.9 and m(SiO2)/m(Al2O3) of 3.0–4.0. This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.
2023, vol. 30, no. 5, pp.
897-907.
https://doi.org/10.1007/s12613-022-2571-8
Abstract:
To effectively separate and recover Co(II) from the leachate of spent lithium-ion battery cathodes, we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system. N\begin{document}${\rm{O}}_2^- $\end{document} ![]()
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To effectively separate and recover Co(II) from the leachate of spent lithium-ion battery cathodes, we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system. N
2023, vol. 30, no. 5, pp.
908-916.
https://doi.org/10.1007/s12613-022-2493-5
Abstract:
It was discovered the application of Al2O3 nanofluid as lubricant for steel hot rolling could synchronously achieve oxidation protection of strips surface. The underlying mechanism was investigated through hot rolling tests and molecular dynamics (MD) simulations. The employment of Al2O3 nanoparticles contributed to significant enhancement in the lubrication performance of lubricant. The rolled strip exhibited the best surface topography that the roughness reached lowest with the sparsest surface defects. Besides, the oxide scale generated on steel surface was also thinner, and the ratio of Fe2O3 among various iron oxides became lower. It was revealed the above oxidation protection effect of Al2O3 nanofluid was attributed to the deposition of nanoparticles on metal surface during hot rolling. A protective layer in the thickness of about 193 nm was formed to prevent the direct contact between steel matrix and atmosphere, which was mainly composed of Al2O3 and sintered organic molecules. MD simulations confirmed the diffusion of O2 and H2O could be blocked by the Al2O3 layer through physical absorption and penetration barrier effect.
It was discovered the application of Al2O3 nanofluid as lubricant for steel hot rolling could synchronously achieve oxidation protection of strips surface. The underlying mechanism was investigated through hot rolling tests and molecular dynamics (MD) simulations. The employment of Al2O3 nanoparticles contributed to significant enhancement in the lubrication performance of lubricant. The rolled strip exhibited the best surface topography that the roughness reached lowest with the sparsest surface defects. Besides, the oxide scale generated on steel surface was also thinner, and the ratio of Fe2O3 among various iron oxides became lower. It was revealed the above oxidation protection effect of Al2O3 nanofluid was attributed to the deposition of nanoparticles on metal surface during hot rolling. A protective layer in the thickness of about 193 nm was formed to prevent the direct contact between steel matrix and atmosphere, which was mainly composed of Al2O3 and sintered organic molecules. MD simulations confirmed the diffusion of O2 and H2O could be blocked by the Al2O3 layer through physical absorption and penetration barrier effect.
2023, vol. 30, no. 5, pp.
917-929.
https://doi.org/10.1007/s12613-022-2568-3
Abstract:
In the present work, Fe–Mn–Al–C powder mixtures were manufactured by elemental powders with different ball milling time, and the porous high-Mn and high-Al steel was fabricated by powder sintering. The results indicated that the powder size significantly decreased, and the morphology of the Fe powder tended to be increasingly flat as the milling time increased. However, the prolonged milling duration had limited impact on the phase transition of the powder mixture. The main phases of all the samples sintered at 640°C were α-Fe, α-Mn and Al, and a small amount of Fe2Al5 and Al8Mn5. When the sintering temperature increased to 1200°C, the phase composition was mainly comprised of γ-Fe and α-Fe. The weight loss fraction of the sintered sample decreased with milling time, i.e., 8.3wt% after 20 h milling compared to 15.3wt% for 10 h. The Mn depletion region (MDR) for the 10, 15, and 20 h milled samples was about 780, 600, and 370 μm, respectively. The total porosity of samples sintered at 640°C decreased from ~46.6vol% for the 10 h milled powder to ~44.2vol% for 20 h milled powder. After sintering at 1200°C, the total porosity of sintered samples prepared by 10 and 20 h milled powder was ~58.3vol% and ~51.3vol%, respectively. The compressive strength and ductility of the 1200°C sintered porous steel increased as the milling time increased.
In the present work, Fe–Mn–Al–C powder mixtures were manufactured by elemental powders with different ball milling time, and the porous high-Mn and high-Al steel was fabricated by powder sintering. The results indicated that the powder size significantly decreased, and the morphology of the Fe powder tended to be increasingly flat as the milling time increased. However, the prolonged milling duration had limited impact on the phase transition of the powder mixture. The main phases of all the samples sintered at 640°C were α-Fe, α-Mn and Al, and a small amount of Fe2Al5 and Al8Mn5. When the sintering temperature increased to 1200°C, the phase composition was mainly comprised of γ-Fe and α-Fe. The weight loss fraction of the sintered sample decreased with milling time, i.e., 8.3wt% after 20 h milling compared to 15.3wt% for 10 h. The Mn depletion region (MDR) for the 10, 15, and 20 h milled samples was about 780, 600, and 370 μm, respectively. The total porosity of samples sintered at 640°C decreased from ~46.6vol% for the 10 h milled powder to ~44.2vol% for 20 h milled powder. After sintering at 1200°C, the total porosity of sintered samples prepared by 10 and 20 h milled powder was ~58.3vol% and ~51.3vol%, respectively. The compressive strength and ductility of the 1200°C sintered porous steel increased as the milling time increased.
2023, vol. 30, no. 5, pp.
930-938.
https://doi.org/10.1007/s12613-022-2566-5
Abstract:
The martensitic transformation, mechanical, and magnetic properties of the Ni2Mn1.5−xCuxTi0.5 (x = 0.125, 0.25, 0.375, 0.5) and Ni2−yCoyMn1.5−xCuxTi0.5 [(x = 0.125, y = 0.125, 0.25, 0.375, 0.5) and (x = 0.125, 0.25, 0.375, y = 0.625)] alloys were systematically studied by the first-principles calculations. For the formation energy, the martensite is smaller than the austenite, the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation. The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni2Mn1.5−xCuxTi0.5 and Ni2−yCoyMn1.5−xCuxTi0.5 (y < 0.625) alloys. When y = 0.625 in the Ni2−yCoyMn1.5−xCuxTi0.5 series, the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state. Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy. Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance, but reduce the toughness in the Ni–Mn–Cu–Ti alloy. And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys. The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.
The martensitic transformation, mechanical, and magnetic properties of the Ni2Mn1.5−xCuxTi0.5 (x = 0.125, 0.25, 0.375, 0.5) and Ni2−yCoyMn1.5−xCuxTi0.5 [(x = 0.125, y = 0.125, 0.25, 0.375, 0.5) and (x = 0.125, 0.25, 0.375, y = 0.625)] alloys were systematically studied by the first-principles calculations. For the formation energy, the martensite is smaller than the austenite, the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation. The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni2Mn1.5−xCuxTi0.5 and Ni2−yCoyMn1.5−xCuxTi0.5 (y < 0.625) alloys. When y = 0.625 in the Ni2−yCoyMn1.5−xCuxTi0.5 series, the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state. Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy. Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance, but reduce the toughness in the Ni–Mn–Cu–Ti alloy. And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys. The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.
2023, vol. 30, no. 5, pp.
939-948.
https://doi.org/10.1007/s12613-022-2549-6
Abstract:
The evolution of microstructure, elemental segregation, and precipitation in GH4742 superalloy under a wide range of cooling rates was investigated using zonal melting liquid metal cooling (ZMLMC) experiments. Comparing various nickel-based superalloys, the primary dendrite spacing is significantly linearly correlated with G−1/2V−1/4 at high cooling rates, where G and V are temperature gradient and drawing rate, respectively. As the cooling rate decreases, the primary dendrite spacing increases in a dispersive manner. The secondary dendrite arm spacing is significantly correlated with (GV)−0.4 for all cooling rate ranges. The degree of elemental segregation increases and then decreases as the cooling rate increases, which is due to the competition between solute counter-diffusion and dendrite tip subcooling. With increasing the solidification rate, the size of γ′, carbides, and non-metallic inclusions gradually decreases. The morphology of the γ′ precipitate changes from plume-like to cubic to spherical. The morphology of carbide changes from block to fine-strip then to Chinese-script. The morphology of carbide is controlled by both dendrite interstitial shape and element diffusion. The inclusions are mainly composite inclusions, which usually show the growth of Ti(C,N) with oxide as the heterogeneous nucleation center and carbide on the outer surface of the carbonitride. As the cooling rate increases, the number density of composite inclusions first increases and then decreases, which is closely related to the elemental segregation behavior.
The evolution of microstructure, elemental segregation, and precipitation in GH4742 superalloy under a wide range of cooling rates was investigated using zonal melting liquid metal cooling (ZMLMC) experiments. Comparing various nickel-based superalloys, the primary dendrite spacing is significantly linearly correlated with G−1/2V−1/4 at high cooling rates, where G and V are temperature gradient and drawing rate, respectively. As the cooling rate decreases, the primary dendrite spacing increases in a dispersive manner. The secondary dendrite arm spacing is significantly correlated with (GV)−0.4 for all cooling rate ranges. The degree of elemental segregation increases and then decreases as the cooling rate increases, which is due to the competition between solute counter-diffusion and dendrite tip subcooling. With increasing the solidification rate, the size of γ′, carbides, and non-metallic inclusions gradually decreases. The morphology of the γ′ precipitate changes from plume-like to cubic to spherical. The morphology of carbide changes from block to fine-strip then to Chinese-script. The morphology of carbide is controlled by both dendrite interstitial shape and element diffusion. The inclusions are mainly composite inclusions, which usually show the growth of Ti(C,N) with oxide as the heterogeneous nucleation center and carbide on the outer surface of the carbonitride. As the cooling rate increases, the number density of composite inclusions first increases and then decreases, which is closely related to the elemental segregation behavior.
2023, vol. 30, no. 5, pp.
949-958.
https://doi.org/10.1007/s12613-022-2572-7
Abstract:
Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated. The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed of α-Mg, β-Li, Mg–Li–Zn, and Mn phases. The microstructure of the test alloy is refined owing to dynamic recrystallization (DRX) during hot extrusion. After hot extrusion, the crushed precipitates are uniformly distributed in the test alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of as-extruded alloy reach 156 MPa, 208 MPa, and 32.3%, respectively, which are much better than that of as-cast alloy. Furthermore, the as-extruded and as-cast alloys both exhibit superior damping capacities, with the damping capacity (\begin{document}$ {Q}^{-1} $\end{document} ![]()
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Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated. The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed of α-Mg, β-Li, Mg–Li–Zn, and Mn phases. The microstructure of the test alloy is refined owing to dynamic recrystallization (DRX) during hot extrusion. After hot extrusion, the crushed precipitates are uniformly distributed in the test alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of as-extruded alloy reach 156 MPa, 208 MPa, and 32.3%, respectively, which are much better than that of as-cast alloy. Furthermore, the as-extruded and as-cast alloys both exhibit superior damping capacities, with the damping capacity (
2023, vol. 30, no. 5, pp.
959-969.
https://doi.org/10.1007/s12613-022-2542-0
Abstract:
Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys. However, its application is limited due to its defects. This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition. The morphology and structure were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD). Image-Pro Plus 6.0 was used to determine the porosity of the coating, which was decreased from 8.53% to 0.51%. Simultaneously, the coating thickness was increased by a factor of four. The anti-corrosion performance of each sample was evaluated using electrochemical tests, and the findings revealed that the corrosion current density of coatings (icorr) of the samples were lowered from 9.152 × 10–2 to 6.152 × 10–4 mA·cm−2, and the total resistance (RT) of the samples were enhanced from 2.19 × 104 to 2.33 × 105 Ω·cm2. The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h. In addition, the mechanism of PEO self-sealing behavior was described in this article.
Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys. However, its application is limited due to its defects. This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition. The morphology and structure were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD). Image-Pro Plus 6.0 was used to determine the porosity of the coating, which was decreased from 8.53% to 0.51%. Simultaneously, the coating thickness was increased by a factor of four. The anti-corrosion performance of each sample was evaluated using electrochemical tests, and the findings revealed that the corrosion current density of coatings (icorr) of the samples were lowered from 9.152 × 10–2 to 6.152 × 10–4 mA·cm−2, and the total resistance (RT) of the samples were enhanced from 2.19 × 104 to 2.33 × 105 Ω·cm2. The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h. In addition, the mechanism of PEO self-sealing behavior was described in this article.
2023, vol. 30, no. 5, pp.
970-976.
https://doi.org/10.1007/s12613-022-2529-x
Abstract:
Efficient catalysts enable MgH2 with superior hydrogen storage performance. Herein, we successfully synthesized a catalyst composed of Ce and Ni (i.e. CeNi5 alloy) with splendid catalytic action for boosting the hydrogen storage property of magnesium hydride (MgH2). The MgH2–5wt%CeNi5 composite’s initial hydrogen release temperature was reduced to 174°C and approximately 6.4wt% H2 was released at 275°C within 10 min. Besides, the dehydrogenation enthalpy of MgH2 was slightly decreased by adding CeNi5. For hydrogenation, the fully dehydrogenated sample absorbed 4.8wt% H2 at a low temperature of 175°C. The hydrogenation apparent activation energy was decreased from (73.60 ± 1.79) to (46.12 ± 7.33) kJ/mol. Microstructure analysis revealed that Mg2Ni/Mg2NiH4 and CeH2.73 were formed during the process of hydrogen absorption and desorption, exerted combined “Gateway” and “Spillover” effects to reduce the operating temperature and improve the hydrogen storage kinetics of MgH2. Our work provides an example of merging “Gateway” and “Spillover” effects in one catalyst and may shed light on designing novel highly-effective catalysts for MgH2 in near future.
Efficient catalysts enable MgH2 with superior hydrogen storage performance. Herein, we successfully synthesized a catalyst composed of Ce and Ni (i.e. CeNi5 alloy) with splendid catalytic action for boosting the hydrogen storage property of magnesium hydride (MgH2). The MgH2–5wt%CeNi5 composite’s initial hydrogen release temperature was reduced to 174°C and approximately 6.4wt% H2 was released at 275°C within 10 min. Besides, the dehydrogenation enthalpy of MgH2 was slightly decreased by adding CeNi5. For hydrogenation, the fully dehydrogenated sample absorbed 4.8wt% H2 at a low temperature of 175°C. The hydrogenation apparent activation energy was decreased from (73.60 ± 1.79) to (46.12 ± 7.33) kJ/mol. Microstructure analysis revealed that Mg2Ni/Mg2NiH4 and CeH2.73 were formed during the process of hydrogen absorption and desorption, exerted combined “Gateway” and “Spillover” effects to reduce the operating temperature and improve the hydrogen storage kinetics of MgH2. Our work provides an example of merging “Gateway” and “Spillover” effects in one catalyst and may shed light on designing novel highly-effective catalysts for MgH2 in near future.
2023, vol. 30, no. 5, pp.
977-987.
https://doi.org/10.1007/s12613-022-2533-1
Abstract:
Understanding the influence of purities on the electrochemical performance of pure aluminum (Al) in alkaline media for Al–air batteries is significant. Herein, we comprehensively investigate secondary phase precipitate (SPP)-induced localized corrosion of pure Al inNaOH solution mainly based on quasi-in-situ and cross-section observations under scanning electron microscopy coupled with finite element simulation. The experimental results indicate that Al–Fe SPPs appear as clusters and are coherent with the Al substrate. In alkaline media, Al–Fe SPPs exhibit more positive potentials than the substrate, thus aggravating localized galvanic corrosion as cathodic phases. Moreover, finite element simulation indicates that the irregular geometry coupled with potential difference produces the non-uniform current density distribution inside the SPP cluster, and the current density on the Al substrate gradually decreases with distance.
Understanding the influence of purities on the electrochemical performance of pure aluminum (Al) in alkaline media for Al–air batteries is significant. Herein, we comprehensively investigate secondary phase precipitate (SPP)-induced localized corrosion of pure Al inNaOH solution mainly based on quasi-in-situ and cross-section observations under scanning electron microscopy coupled with finite element simulation. The experimental results indicate that Al–Fe SPPs appear as clusters and are coherent with the Al substrate. In alkaline media, Al–Fe SPPs exhibit more positive potentials than the substrate, thus aggravating localized galvanic corrosion as cathodic phases. Moreover, finite element simulation indicates that the irregular geometry coupled with potential difference produces the non-uniform current density distribution inside the SPP cluster, and the current density on the Al substrate gradually decreases with distance.
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