Search2018 Vol. 25, No. 10
Display Method:
2018, vol. 25, no. 10, pp.
1113-1122.
https://doi.org/10.1007/s12613-018-1662-z
Abstract:
Given the gradual increase in the chlorite content of hematite ores, pulp properties seriously deteriorate during flotation. The traditional anion reverse flotation of hematite cannot effectively eliminate the effects of chlorite, leading to a significant decrease in the total Fe (TFe) grade of the concentrate. In this work, the effect of sodium alginate on the reverse flotation of hematite was systematically investigated. Flotation tests of artificially mixed ores were conducted, and the results showed that sodium alginate can significantly improve the removal rates of quartz and chlorite. The adsorption measurements, infrared spectroscopy, and contact angle tests demonstrated that sodium alginate adsorbs on the quartz surface by chelating with calcium ions, thereby weakening the steric hindrance of oleate ions and increasing the adsorption capacity of sodium oleate to ultimately improve the removal rate of quartz. Furthermore, owing to its lower density and fine particle size, chlorite is easily entrained into the foam layer. Sodium alginate dramatically increases the liquid-to-gas ratio of the foam layer by increasing pulp viscosity, thereby increasing the entrainment rate of chlorite and finally improving its removal rate. The core content of this thesis bears significance in improving the Fe grade in the reverse flotation of chlorite-containing hematite.
Given the gradual increase in the chlorite content of hematite ores, pulp properties seriously deteriorate during flotation. The traditional anion reverse flotation of hematite cannot effectively eliminate the effects of chlorite, leading to a significant decrease in the total Fe (TFe) grade of the concentrate. In this work, the effect of sodium alginate on the reverse flotation of hematite was systematically investigated. Flotation tests of artificially mixed ores were conducted, and the results showed that sodium alginate can significantly improve the removal rates of quartz and chlorite. The adsorption measurements, infrared spectroscopy, and contact angle tests demonstrated that sodium alginate adsorbs on the quartz surface by chelating with calcium ions, thereby weakening the steric hindrance of oleate ions and increasing the adsorption capacity of sodium oleate to ultimately improve the removal rate of quartz. Furthermore, owing to its lower density and fine particle size, chlorite is easily entrained into the foam layer. Sodium alginate dramatically increases the liquid-to-gas ratio of the foam layer by increasing pulp viscosity, thereby increasing the entrainment rate of chlorite and finally improving its removal rate. The core content of this thesis bears significance in improving the Fe grade in the reverse flotation of chlorite-containing hematite.
2018, vol. 25, no. 10, pp.
1123-1131.
https://doi.org/10.1007/s12613-018-1663-y
Abstract:
The flotation separation of chalcopyrite from monoclinic pyrrhotite using food-grade guar gum (FGG) as a depressant was studied through flotation tests, kinetic studies, dynamic potential measurements, adsorption experiments, and infrared spectral analyses. The microflotation results showed that the flotation separation of chalcopyrite from monoclinic pyrrhotite could not be realized by adding mixed aerofloat (CSU11) alone. The depressant FGG exhibited a selective depression effect on monoclinic pyrrhotite by controlling the pulp pH range from 5.0 to 6.0, with a maximum floatability variation of 79.36% in the presence of CSU11. The flotation kinetics, zeta-potential, adsorption, and infrared spectroscopy studies revealed that the FGG could absorb more strongly on the surface of monoclinic pyrrhotite than on the surface of chalcopyrite. In addition, the results revealed that the interaction of FGG with the monoclinic pyrrhotite surface was governed primarily by strong chemisorption, whereas FGG mainly bonded to chalcopyrite through hydrogen bonding. This difference was responsible for the excellent depression selectivity of FGG toward monoclinic pyrrhotite flotation and weak depression effect toward chalcopyrite flotation.
The flotation separation of chalcopyrite from monoclinic pyrrhotite using food-grade guar gum (FGG) as a depressant was studied through flotation tests, kinetic studies, dynamic potential measurements, adsorption experiments, and infrared spectral analyses. The microflotation results showed that the flotation separation of chalcopyrite from monoclinic pyrrhotite could not be realized by adding mixed aerofloat (CSU11) alone. The depressant FGG exhibited a selective depression effect on monoclinic pyrrhotite by controlling the pulp pH range from 5.0 to 6.0, with a maximum floatability variation of 79.36% in the presence of CSU11. The flotation kinetics, zeta-potential, adsorption, and infrared spectroscopy studies revealed that the FGG could absorb more strongly on the surface of monoclinic pyrrhotite than on the surface of chalcopyrite. In addition, the results revealed that the interaction of FGG with the monoclinic pyrrhotite surface was governed primarily by strong chemisorption, whereas FGG mainly bonded to chalcopyrite through hydrogen bonding. This difference was responsible for the excellent depression selectivity of FGG toward monoclinic pyrrhotite flotation and weak depression effect toward chalcopyrite flotation.
2018, vol. 25, no. 10, pp.
1132-1139.
https://doi.org/10.1007/s12613-018-1664-x
Abstract:
To provide a theoretical basis for a suitable process to extract gold from refractory gold concentrates, process mineralogy on the acid leaching residue of gold calcine was studied by chemical composition, X-ray diffraction, scanning electron microscopy-energy spectrum, and mineral dissociation analysis. The results showed that the acid leaching residue contained Au 68.22 g/t, Ag 92.71 g/t, Fe 0.44%, As 0.10%, and S 0.55%. Gold and silver minerals existed as native gold, argentite, and proustite. Quartz, the main gangue mineral, accounted for 78.33wt/%. The dissociation degree analysis showed that the proportions of monomer and exposed gold in acid leaching residue were 96.66wt%. The cyanidation results showed that the cyanide gold leaching rate of acid leaching residues was close to 100wt%. However, the maximum cyanide gold leaching rate of gold calcine was only 85.31wt%. This suggests that acid leaching can increase the gold dissolution rate in the cyanide process.
To provide a theoretical basis for a suitable process to extract gold from refractory gold concentrates, process mineralogy on the acid leaching residue of gold calcine was studied by chemical composition, X-ray diffraction, scanning electron microscopy-energy spectrum, and mineral dissociation analysis. The results showed that the acid leaching residue contained Au 68.22 g/t, Ag 92.71 g/t, Fe 0.44%, As 0.10%, and S 0.55%. Gold and silver minerals existed as native gold, argentite, and proustite. Quartz, the main gangue mineral, accounted for 78.33wt/%. The dissociation degree analysis showed that the proportions of monomer and exposed gold in acid leaching residue were 96.66wt%. The cyanidation results showed that the cyanide gold leaching rate of acid leaching residues was close to 100wt%. However, the maximum cyanide gold leaching rate of gold calcine was only 85.31wt%. This suggests that acid leaching can increase the gold dissolution rate in the cyanide process.
2018, vol. 25, no. 10, pp.
1140-1147.
https://doi.org/10.1007/s12613-018-1665-9
Abstract:
To improve the efficiency of melting modification for stainless steel (SS) slag, a shear force was introduced in this work and its effects on the spinel and silicate melt were experimentally investigated. The results indicated that the use of shear force changed the nucleation and growth behaviors of spinel and that the effects of shear force varied with its intensity. The aggregation behavior of spinel under different shear-force conditions was studied, revealing that large spinel clusters could be formed when the stirring speed was controlled. However, no notable change in the melt structure of the silicate was detected in this study. The optimal stirring speed for the melting modification treatment was 50 r·min-1, which substantially promoted spinel growth and aggregation, resulting in modified SS slag with excellent chromium sequestration capability.
To improve the efficiency of melting modification for stainless steel (SS) slag, a shear force was introduced in this work and its effects on the spinel and silicate melt were experimentally investigated. The results indicated that the use of shear force changed the nucleation and growth behaviors of spinel and that the effects of shear force varied with its intensity. The aggregation behavior of spinel under different shear-force conditions was studied, revealing that large spinel clusters could be formed when the stirring speed was controlled. However, no notable change in the melt structure of the silicate was detected in this study. The optimal stirring speed for the melting modification treatment was 50 r·min-1, which substantially promoted spinel growth and aggregation, resulting in modified SS slag with excellent chromium sequestration capability.
2018, vol. 25, no. 10, pp.
1148-1155.
https://doi.org/10.1007/s12613-018-1666-8
Abstract:
Cast stainless steels used in nuclear power plants suffer from fracture toughness losses owing to thermal aging after long-term service at temperatures ranging from 280-320℃. To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 350, 380, and 400℃ for up to 10000 h. Microhardness and Charpy impact energies were measured at different aging times. The microhardness of ferrite increased drastically over the initial aging time of 2000 h at 380 and 400℃ and then slowly reached HV0.01 560. In contrast to this observed change in microhardness, Charpy impact energies sharply decreased after initial aging and then gradually reached a minimum value. Taking the microhardness of the ferrite phase as the parameter describing the thermal kinetics of the stainless steel samples, the activation energy of thermal aging was calculated to be 51 kJ/mol. Correlations between the thermal aging parameter, P, and ferrite microhardness and between P and Charpy impact energy were also analyzed. The results showed that the activation energy calculated from the ferrite microhardness is much more reasonable than that obtained using other parameters, such as chemical composition and impact energy.
Cast stainless steels used in nuclear power plants suffer from fracture toughness losses owing to thermal aging after long-term service at temperatures ranging from 280-320℃. To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 350, 380, and 400℃ for up to 10000 h. Microhardness and Charpy impact energies were measured at different aging times. The microhardness of ferrite increased drastically over the initial aging time of 2000 h at 380 and 400℃ and then slowly reached HV0.01 560. In contrast to this observed change in microhardness, Charpy impact energies sharply decreased after initial aging and then gradually reached a minimum value. Taking the microhardness of the ferrite phase as the parameter describing the thermal kinetics of the stainless steel samples, the activation energy of thermal aging was calculated to be 51 kJ/mol. Correlations between the thermal aging parameter, P, and ferrite microhardness and between P and Charpy impact energy were also analyzed. The results showed that the activation energy calculated from the ferrite microhardness is much more reasonable than that obtained using other parameters, such as chemical composition and impact energy.
2018, vol. 25, no. 10, pp.
1156-1165.
https://doi.org/10.1007/s12613-018-1667-7
Abstract:
Three oxide-dispersion-strengthened (ODS) steels with compositions of Fe-14Cr-2W-0.2V-0.07Ta-0.3Y2O3 (wt%, so as the follows) (14Y), Fe-14Cr-2W-0.2V-0.07Ta-1Al-0.3Y2O3 (14YAl), and Fe-14Cr-2W-0.2V-0.07Ta-0.3Ti-0.3 Y2O3 (14YTi) were fabricated by hot pressing. Transmission electron microscopy (TEM) was used to characterize the microstructures and nanoparticles of these ODS steels. According to the TEM results, 14Y, 14YAl, and 14YTi ODS steels present similar bimodal structures containing both large and small grains. The addition of Al or Ti has no obvious effect on the microstructure of the steels. The spatial and size distribution of the nanoparticles was also analyzed. The results indicate that the average size of nanoparticles in the 14YTi ODS steel is smaller than that in the 14YAl ODS steel. Nanoparticles such as Y2O3, Y3Al5O12 and YAlO3, and Y2Ti2O7 were identified in the 14Y, 14YAl, and 14YTi ODS steels, respectively.
Three oxide-dispersion-strengthened (ODS) steels with compositions of Fe-14Cr-2W-0.2V-0.07Ta-0.3Y2O3 (wt%, so as the follows) (14Y), Fe-14Cr-2W-0.2V-0.07Ta-1Al-0.3Y2O3 (14YAl), and Fe-14Cr-2W-0.2V-0.07Ta-0.3Ti-0.3 Y2O3 (14YTi) were fabricated by hot pressing. Transmission electron microscopy (TEM) was used to characterize the microstructures and nanoparticles of these ODS steels. According to the TEM results, 14Y, 14YAl, and 14YTi ODS steels present similar bimodal structures containing both large and small grains. The addition of Al or Ti has no obvious effect on the microstructure of the steels. The spatial and size distribution of the nanoparticles was also analyzed. The results indicate that the average size of nanoparticles in the 14YTi ODS steel is smaller than that in the 14YAl ODS steel. Nanoparticles such as Y2O3, Y3Al5O12 and YAlO3, and Y2Ti2O7 were identified in the 14Y, 14YAl, and 14YTi ODS steels, respectively.
2018, vol. 25, no. 10, pp.
1166-1172.
https://doi.org/10.1007/s12613-018-1668-6
Abstract:
Although excellent recyclability is one of the advantages of Al alloys, a recycling process can reduce different properties of these alloys by adding coarse AlFeSi particles into the alloys' microstructures. One of the well-known methods for modifying the microstructure of metallic materials is the imposition of severe plastic deformation (SPD). Nevertheless, the microstructure evolutions of recycled Al alloys containing extraordinary fractions of AlFeSi particles during SPD processing have seldom been considered. The aim of the present work is to study the microstructure evolution of a recycled Al-Fe-Si-Cu alloy during SPD processing. For this purpose, tubular specimens of the mentioned alloy were subjected to different numbers of passes of a recently developed SPD process called tube channel pressing (TCP); their microstructures were then studied using different techniques. The results show that coarse AlFeSi particles are fragmented into finer particles after processing by TCP. However, decomposition and dissolution of AlFeSi particles through TCP processing are negligible. In addition, TCP processing results in an increase in hardness of the alloy, which is attributed to the refinement of grains, to an increase of the dislocation density, and to the fragmentation of AlFeSi particles.
Although excellent recyclability is one of the advantages of Al alloys, a recycling process can reduce different properties of these alloys by adding coarse AlFeSi particles into the alloys' microstructures. One of the well-known methods for modifying the microstructure of metallic materials is the imposition of severe plastic deformation (SPD). Nevertheless, the microstructure evolutions of recycled Al alloys containing extraordinary fractions of AlFeSi particles during SPD processing have seldom been considered. The aim of the present work is to study the microstructure evolution of a recycled Al-Fe-Si-Cu alloy during SPD processing. For this purpose, tubular specimens of the mentioned alloy were subjected to different numbers of passes of a recently developed SPD process called tube channel pressing (TCP); their microstructures were then studied using different techniques. The results show that coarse AlFeSi particles are fragmented into finer particles after processing by TCP. However, decomposition and dissolution of AlFeSi particles through TCP processing are negligible. In addition, TCP processing results in an increase in hardness of the alloy, which is attributed to the refinement of grains, to an increase of the dislocation density, and to the fragmentation of AlFeSi particles.
2018, vol. 25, no. 10, pp.
1173-1180.
https://doi.org/10.1007/s12613-018-1669-5
Abstract:
The flexible rolling process (FRP) is a novel three-dimensional (3D) forming process that combines the multipoint and traditional rolling forming. The principle of FRP is based on thickness thinning, so the deformation path significantly impacts the forming effect. In this study, the multistep forming process with different deformation paths was introduced to improve the forming effect of FRP. For instance, with the convex surface part, three finite element models of multistep FRP (MSFRP) were established. The corresponding numerical simulations and forming experiments performed among different deformation paths showed the surface part with a longer effective forming region was obtained and the forming regions with more steps in MSFRP were smoother. Thus, the sheet-metal utilization rate was greatly improved. Moreover, the MSFRP can improve the longitudinal bending effect dramatically and thereby endowing the forming part with a better forming effect. Therefore, MSFRP is a prospective method for broad applications.
The flexible rolling process (FRP) is a novel three-dimensional (3D) forming process that combines the multipoint and traditional rolling forming. The principle of FRP is based on thickness thinning, so the deformation path significantly impacts the forming effect. In this study, the multistep forming process with different deformation paths was introduced to improve the forming effect of FRP. For instance, with the convex surface part, three finite element models of multistep FRP (MSFRP) were established. The corresponding numerical simulations and forming experiments performed among different deformation paths showed the surface part with a longer effective forming region was obtained and the forming regions with more steps in MSFRP were smoother. Thus, the sheet-metal utilization rate was greatly improved. Moreover, the MSFRP can improve the longitudinal bending effect dramatically and thereby endowing the forming part with a better forming effect. Therefore, MSFRP is a prospective method for broad applications.
2018, vol. 25, no. 10, pp.
1181-1190.
https://doi.org/10.1007/s12613-018-1670-z
Abstract:
The effects of the microalloying element niobium (Nb) on the microstructure and mechanical properties of the hot stamped steel 38MnB5 were investigated. The impact of Nb addition on the microstructure was studied through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The experimental results indicated that the microstructures of the steel containing Nb were finer than those of the steel without Nb. Moreover, Nb mainly presented as a second-phase particle in 38MnB5 steel, and the particles included Nb carbonitrides. In addition, the tensile strength and elongation of the hot rolled and hot stamped steels were also measured, and they demonstrated that the appropriate addition of Nb was beneficial to the mechanical properties of 38MnB5. Under the same conditions, the tensile strength of 38MnB5Nb was higher than that of 38MnB5, which increased from 2011 to 2179 MPa. The yield strength also increased from 1316 to 1476 MPa, and the elongation increased from 5.92% to 6.64%. Overall, Nb had a positive effect on the performance of the hot stamped steel.
The effects of the microalloying element niobium (Nb) on the microstructure and mechanical properties of the hot stamped steel 38MnB5 were investigated. The impact of Nb addition on the microstructure was studied through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The experimental results indicated that the microstructures of the steel containing Nb were finer than those of the steel without Nb. Moreover, Nb mainly presented as a second-phase particle in 38MnB5 steel, and the particles included Nb carbonitrides. In addition, the tensile strength and elongation of the hot rolled and hot stamped steels were also measured, and they demonstrated that the appropriate addition of Nb was beneficial to the mechanical properties of 38MnB5. Under the same conditions, the tensile strength of 38MnB5Nb was higher than that of 38MnB5, which increased from 2011 to 2179 MPa. The yield strength also increased from 1316 to 1476 MPa, and the elongation increased from 5.92% to 6.64%. Overall, Nb had a positive effect on the performance of the hot stamped steel.
2018, vol. 25, no. 10, pp.
1191-1200.
https://doi.org/10.1007/s12613-018-1671-y
Abstract:
A 1040℃-hot-deformed Ti2AlNb-based alloy solution-treated at 950℃ and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deformed alloys were measured. The results indicated that the microstructure of the deformed Ti2AlNb-based alloy specimens comprise coarse O lath, fine O lath, equiaxed O/α2, and acicular O phase. More O phase was generated in the deformed alloy after heat treatment because the acicular O phase was more likely to nucleate and grow along the deformation-induced crystal defects such as dislocations and subgrain boundaries. After deformation and subsequent heat treatment, the acicular O phase of the resultant alloy became finer compared to that of the undeformed alloy, and the acicular O phase became coarser and longer with the elevated aging temperature, while the width of the O lath exhibited unobvious variations. The hot deformation facilitated the dissolution of the O lath but accelerated the precipitation of the acicular O phase. When the 950℃-solution-treated deformed Ti2AlNb-based alloy was then aged at 750℃ for different periods, the phase content was nearly invariable, O and B2 phases eventually reached equilibrium, and the microstructure became stable and homogeneous.
A 1040℃-hot-deformed Ti2AlNb-based alloy solution-treated at 950℃ and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deformed alloys were measured. The results indicated that the microstructure of the deformed Ti2AlNb-based alloy specimens comprise coarse O lath, fine O lath, equiaxed O/α2, and acicular O phase. More O phase was generated in the deformed alloy after heat treatment because the acicular O phase was more likely to nucleate and grow along the deformation-induced crystal defects such as dislocations and subgrain boundaries. After deformation and subsequent heat treatment, the acicular O phase of the resultant alloy became finer compared to that of the undeformed alloy, and the acicular O phase became coarser and longer with the elevated aging temperature, while the width of the O lath exhibited unobvious variations. The hot deformation facilitated the dissolution of the O lath but accelerated the precipitation of the acicular O phase. When the 950℃-solution-treated deformed Ti2AlNb-based alloy was then aged at 750℃ for different periods, the phase content was nearly invariable, O and B2 phases eventually reached equilibrium, and the microstructure became stable and homogeneous.
2018, vol. 25, no. 10, pp.
1201-1207.
https://doi.org/10.1007/s12613-018-1672-x
Abstract:
In this work, we synthesized LaFeO3-xwt%Ni (x=0, 5, 10, 15) composites via a solid-state reaction method by adding Ni to the reactants, La2O3 and Fe2O3. Field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) results revealed that Ni powders evenly dispersed among the LaFeO3 particles and apparently reduced their aggregation, which imparted the composites with a loose structure. Moreover, the Ni formed a conductive network, thus improving the conductivity of the composites. The maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 266.8 mAh·g-1 (x=0) to 339.7 mAh·g-1 (x=10). In particular, the high-rate dischargeability of the LaFeO3-10wt%Ni electrode at a discharge current density of 1500 mA·g-1 reached 54.6%, which was approximately 1.5 times higher than that of the pure LaFeO3. Such a Ni-modified loose structure not only increased the charge transfer rate on the surface of the LaFeO3 particles but also enhanced the hydrogen diffusion rate in the bulk LaFeO3.
In this work, we synthesized LaFeO3-xwt%Ni (x=0, 5, 10, 15) composites via a solid-state reaction method by adding Ni to the reactants, La2O3 and Fe2O3. Field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) results revealed that Ni powders evenly dispersed among the LaFeO3 particles and apparently reduced their aggregation, which imparted the composites with a loose structure. Moreover, the Ni formed a conductive network, thus improving the conductivity of the composites. The maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 266.8 mAh·g-1 (x=0) to 339.7 mAh·g-1 (x=10). In particular, the high-rate dischargeability of the LaFeO3-10wt%Ni electrode at a discharge current density of 1500 mA·g-1 reached 54.6%, which was approximately 1.5 times higher than that of the pure LaFeO3. Such a Ni-modified loose structure not only increased the charge transfer rate on the surface of the LaFeO3 particles but also enhanced the hydrogen diffusion rate in the bulk LaFeO3.
2018, vol. 25, no. 10, pp.
1208-1216.
https://doi.org/10.1007/s12613-018-1673-9
Abstract:
The microstructure evolution and electrolysis behavior of (Cu52Ni30Fe18)-xNiFe2O4 (x=40wt%, 50wt%, 60wt%, and 70wt%) composite inert anodes for aluminum electrowinning were studied. NiFe2O4 was synthesized by solid-state reaction at 950℃. The dense anode blocks were prepared by ball-milling followed by sintering under a N2 atmosphere. The phase evolution of the anodes after sintering was determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicate that a substitution reaction between Fe in the alloy phase and Ni in the oxide phase occurs during the sintering process. The samples were also examined as inert anodes for aluminum electrowinning in the low-temperature KF-NaF-AlF3 molten electrolyte for 24 h. The cell voltage during electrolysis and the corrosion scale on the anodes were analyzed. The results confirm that the scale has a self-repairing function because of the synergistic reaction between the alloy phase with Fe added and the oxide phase. The estimated wear rate of the (Cu52Ni30Fe18)-50NiFe2O4 composite anode is 2.02 cm·a-1.
The microstructure evolution and electrolysis behavior of (Cu52Ni30Fe18)-xNiFe2O4 (x=40wt%, 50wt%, 60wt%, and 70wt%) composite inert anodes for aluminum electrowinning were studied. NiFe2O4 was synthesized by solid-state reaction at 950℃. The dense anode blocks were prepared by ball-milling followed by sintering under a N2 atmosphere. The phase evolution of the anodes after sintering was determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicate that a substitution reaction between Fe in the alloy phase and Ni in the oxide phase occurs during the sintering process. The samples were also examined as inert anodes for aluminum electrowinning in the low-temperature KF-NaF-AlF3 molten electrolyte for 24 h. The cell voltage during electrolysis and the corrosion scale on the anodes were analyzed. The results confirm that the scale has a self-repairing function because of the synergistic reaction between the alloy phase with Fe added and the oxide phase. The estimated wear rate of the (Cu52Ni30Fe18)-50NiFe2O4 composite anode is 2.02 cm·a-1.
2018, vol. 25, no. 10, pp.
1217-1225.
https://doi.org/10.1007/s12613-018-1674-8
Abstract:
A crystalline polyferric sulfate (PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area (SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, X-ray diffraction (XRD) patterns, Fourier-transform infrared (FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10-100 mg/L under acidic, neutral, and alkaline conditions (pH 2.09-9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure (TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.
A crystalline polyferric sulfate (PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area (SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, X-ray diffraction (XRD) patterns, Fourier-transform infrared (FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10-100 mg/L under acidic, neutral, and alkaline conditions (pH 2.09-9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure (TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.
Submit Manuscript
E-mail alert
RSS
