Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn pollutants.However,their utilization is hindered by high prepar...Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn pollutants.However,their utilization is hindered by high preparation costs,low yields,environmental pollution during synthesis,and challenges in regenerating the adsorbent.This study proposes a novel approach to address these limitations by developing nitrogen-doped three-dimensional(3D)polyvinyl alcohol(PVA)crosslinked graphene sponges(N-PGA)using a cross-linking method with ammonium carbonate.This method offers a relatively mild,environmentally friendly approach.Ammonium carbonate serves as both a reducing and modifying agent,facilitating the formation of the intrinsic structure of N-PGA and acting as a nitrogen source.Meanwhile,PVA is utilized as the cross-linking agent.The results demonstrate that N-PGA exhibits a favorable internal 3D hierarchical porous structure and possesses robust mechanical properties.The measured specific surface area(BET)of N-PGA was as high as406.538 m^(2)·g^(-1),which was favorable for its efficient adsorption of Congo red(CR)dye molecules.At an initial concentration of 50 mg·L^(-1),N-PGA achieved an impressive removal rate of 89.6%and an adsorption capacity of 112 mg·g^(-1)for CR dye.Furthermore,it retained 79%of its initial adsorption capacity after 10 cycles,demonstrating excellent regeneration performance.In summary,the synthesized N-PGA displays remarkable efficacy in the adsorption of CR dye in wastewater,opening up new possibilities for utilizing 3D porous graphene nanomaterials as efficient adsorbents in wastewater treatment.展开更多
Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimen...Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.展开更多
High-chromium vanadium-titanium magnetite(HVTM)is a crucial polymetallic-associated resource to be developed.The allpellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future....High-chromium vanadium-titanium magnetite(HVTM)is a crucial polymetallic-associated resource to be developed.The allpellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future.By referencing the production data of vanadium-titanium magnetite blast furnaces,this study explored the softening-melting behavior of high-chromium vanadium-titanium magnetite and obtained the optimal integrated burden based on flux pellets.The results show that the burden with a composition of 70wt%flux pellets and 30wt%acid pellets exhibits the best softening-melting properties.In comparison to that of the single burden,the softening-melting characteristic temperature of this burden composition was higher.The melting interval first increased from 307 to 362℃and then decreased to 282℃.The maximum pressure drop(ΔPmax)decreased from 26.76 to 19.01 kPa.The permeability index(S)dropped from 4643.5 to 2446.8 kPa·℃.The softening-melting properties of the integrated burden were apparently improved.The acid pellets played a role in withstanding load during the softening process.The flux pellets in the integrated burden exhibited a higher slag melting point,which increased the melting temperature during the melting process.The slag homogeneity and the TiC produced by over-reduction led to the gas permeability deterioration of the single burden.The segregation of the flux and acid pellets in the HVTM proportion and basicity mainly led to the better softening-melting properties of the integrated burden.展开更多
Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and...Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.展开更多
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 p...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–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) 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–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) diffusion couples.The regional boundaries of calcium and vanadium are easily identifiable for the CaO–V_(2)O_(5) diffusion couple.Meanwhile,for the MnO_(2)–V_(2)O_(5) diffusion couple,MnO_(2) gradually decomposes to form Mn_(2)O_(3),and vanadium diffuses into the interior of Mn_(2)O_(3).Only a part of vanadium combines with manganese to form the diffusion production layer.CaV_(2)O_(6) and MnV_(2)O_(6) are the interfacial reaction products of the CaO–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) diffusion couples,respectively,whose thicknesses are 39.85 and 32.13μm 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–V_(2)O_(5) diffusion couple is higher than that of the MnO_(2)–V_(2)O_(5) diffusion couple for the same roasting time,and the diffusion reaction between vanadium and calcium is easier than that between vanadium and manganese.展开更多
Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the c...Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation,and the initial CO_(2)chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g.Moreover,the effect of Ca/Mg molar ratio on the morphology,structure,and CO_(2)chemisorption capacity of the calcium-based sorbents were investigated.The results show that the optimal Ca/Mg molar ratio of sorbent for CO_(2)capture was4.2:1,and the skeleton support effect of MgO in calcium-based sorbents was determined.Meanwhile,the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model.There were two processes of CO_(2)chemisorption,and the activation energy of the first stage(reaction control)was found to be lower than that of the second stage(diffusion control).展开更多
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 i...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.展开更多
For the control of surface defects in interstitial-free(IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. Th...For the control of surface defects in interstitial-free(IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. The results show that, at casting speeds of 0.8 and 1.0 m/min, a thin liquid mold flux layer forms and non-uniform floating of argon bubbles occurs, inducing the entrainment and subsequent entrapment of the liquid flux; fine inclusion particles of Al_2O_3 can also aggregate at the solidification front. At higher casting speeds of 1.4 and 1.6 m/min, the liquid mold flux can be entrained and carried deeper into the liquid steel pool because of strong level fluctuations of the liquid steel and the flux. The optimal casting speed is approximately 1.2 m/min, with the most favorable surface flow status and, correspondingly, the lowest number of inclusions near the slab surface.展开更多
The effect of titanium content on the refinement of austenite grain size in as-cast peritectic carbon steel was investigated by fast directional solidification experiments with simulating the solidification and growth...The effect of titanium content on the refinement of austenite grain size in as-cast peritectic carbon steel was investigated by fast directional solidification experiments with simulating the solidification and growth of surface and subsurface austenite in continuously cast slabs.Transmission electron microscope(TEM)and scanning electron microscope(SEM)were used to analyze the size and distribution of Ti(C,N)precipitates during solidification.Based on these results,the pinning pressure of Ti(C,N)precipitates on the growth of coarse columnar grains(CCGs)was studied.The results show that the austenite microstructure of as-cast peritectic carbon steel is mainly composed of the regions of CCGs and fine columnar grains(FCGs).Increasing the content of titanium reduces the region and the short axis of the CCGs.When the content of titanium is 0.09wt%,there is no CCG region.Dispersed microscale particles will firstly form in the liquid,which will decrease the transition temperature from FCGs to CCGs.The chain-like nanoscale Ti(C,N)will precipitate with the decrease of the transition temperature.Furthermore,calculations shows that the refinement of the CCGs is caused by the pinning effect of Ti(C,N)precipitates.展开更多
Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malach...Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malachite reached the maximum and the particle size reached the minimum of 0.7–100 μm. Agglomeration occurred between mineral particles when the rotational speed was increased to 580 r/min in DPG.However, no agglomeration was observed among particles with sizes 0.4–3 μm in WIG. X-ray diffraction analysis showed that, at a 580 r/min rotational speed in DPG, the amorphization degree of malachite was 53.12%, whereas that in WIG was 71.40%, indicating that MA led to amorphization and distortion of crystal structures. In addition, in the Fourier transform infrared(FT-IR) spectra of activated malachite, the bands associated with –OH, CO_3^(2-)and metal lattice vibrations of Cu–O and Cu–OH were weakened, and a new H–O–H bending mode and peaks of gaseous CO_2 appeared, indicating that MA decreased the band energy, enhanced dihydroxylation, and increased the chemical reactivity of the malachite.Furthermore, the leaching behavior of copper ore was greatly improved by MA.展开更多
An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractorie...An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.展开更多
Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In ...Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.展开更多
A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated.Mineralogical studies on the concentrate showed that very fine gold grains(<10μm)were encapsulat...A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated.Mineralogical studies on the concentrate showed that very fine gold grains(<10μm)were encapsulated in pyrite and arsenopyrite,while the proportion of monomer gold was only 21%.The gold-bearing sample was identified as a high-sulfur fine-sized wrapped-type refractory gold concentrate.The gold leaching efficiency obtained by direct cyanidation was only 59.86%.After biooxidation pretreatment,the sulfide minerals were almost completely decomposed,92 wt%of the mineral particles of the biooxidation residue were decreased to<38μm,and the proportion of monomer gold in the biooxidation residue was over 86%.Meanwhile,the gold content in the biooxidation residue was enriched to 55.60 g/t,and the S,Fe,and As contents were reduced to approximately 19.8 wt%,6.97 wt%,and 0.13 wt%,respectively.Ammoniacal thiosulfate was used for gold extraction from the biooxidation residue of the refractory gold concentrate.The results showed that the optimal reagent conditions were 0.18 M thiosulfate,0.02 M copper(II),1.0 M ammonia,and 0.24 M sulfite.Under these conditions,a maximum gold leaching efficiency of 85.05%was obtained.展开更多
A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the...A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the model was validated by the SEM analysis of the industrial products.The type and amount of inclusions in solidification structure of 253 MA heat-resistant steel were predicted by the model,and the valuable results for the inclusions controlling in 253 MA steel were obtained.When the cerium addition increases,the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253 MA steel and the precipitation temperature of SiO2 and MnS decreases.The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2 S,Ce3S4,and MnS as the sulfur content increases.The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases.There is only a small quantity of inclusions containing cerium in 253 MA steel with high cleanliness,i.e.,low oxygen and sulfur contents.By contrast,a mass of SiO2,MnS and Ce2O2 S are formed in steel when the oxygen and sulfur contents are high enough.The condition that MnS precipitates in 253 MA steel is 1.2 w[O]+w[S]>0.01%and SiO2 precipitates when 2 w[O]+w[S]>0.017%(w[S]<0.005%)and w[O]>0.006%(w[S]>0.005%).展开更多
The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning ...The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning electron microscope equipped with energy-dispersive spectrometer,and electron backscattered diffraction.The results indicated that hot deformation amount has no significant effect on the number density of oxide,but the MnS that precipitated on the Ti-Zr oxide surface undergoes extension and breakage,resulting in the changes in oxide aspect ratio.Moreover,the fracture of nitride mainly occurs in the sample with the second pass deformation amount of 42.9%and 71.4%,and the degree of fragmentation of nitride is more serious with the deformation amount increasing.During the hot compression,sulfide undergoes breakage and extension,and with the second pass deformation amount increasing,the breakage and extension of sulfide present a periodic change.Finally,with the increase in hot compression amount,the ferrite types in microstructure change from acicular ferrite and bainitic ferrite to polygonal ferrite,and the ferrite grain size is refined.When the total deformation amount increases from 30%to 80%,the ferrite grain sizes of grain boundary with the misorientation of 4°and 15°decrease from 4.14 and 5.67μm to 3.47 and 4.40μm,respectively.However,when the total deformation amount increases to 80%,the harmful ferrite/pearlite banded structure appears in the micro structure.Refining ferrite grain size and avoiding harmful microstructure are the key for the optimization of hot compression process.展开更多
Advancements in metallurgical technology have led to the emergence of high-performance requirements for metal materials,like high uniformity,high purity,and superfine crystallinity.This has resulted in the development...Advancements in metallurgical technology have led to the emergence of high-performance requirements for metal materials,like high uniformity,high purity,and superfine crystallinity.This has resulted in the development and application of internal cooling source(ICS),vibrational,and vibrational internal cooling source methods in metal solidification processes to afford products with refined crystal grains and large proportions of equiaxed crystals.These methods have gradually been introduced into laboratories and some steel mills over the past few decades.However,there are few successful industrial applications of these methods,as there is no comprehensive understanding of their control theories and principles.Accordingly,the development,basic principles,and classifications of the three types of methods are summarized,and their impact on the solidification of molten metals and the morphology of solid products is discussed.In addition,experimental and numerical simulation-based researches on each type of method are reviewed and their prospects for applications are briefly discussed to control metal solidification.Finally,detailed future perspectives are provided on vibratory strip feeding,ICS,and pulsed magneto-oscillation methods.Hopefully,it will serve as a reference for future studies of the application of these and related methods in metal solidification processes.展开更多
A mathematical model accounting for unsteady mass transfer across interface of a stationary iron droplet immersed into molten slag was established through the volume of fluid coupled with level set method.The Marangon...A mathematical model accounting for unsteady mass transfer across interface of a stationary iron droplet immersed into molten slag was established through the volume of fluid coupled with level set method.The Marangoni effect induced by mass transfer was reproduced successfully,and the hydrodynamic instability phenomena at the interface,such as the Marangoni convection flow,the evolution of the interfacial tension during the mass transfer,and the influence of Marangoni effect on the mass transfer rate,were revealed.The results show that the Marangoni convection flow develops quickly and behaves as an ordered structure in the forms of four pairs of the convection cell at the edge of the droplet once the oxygen transfer across the interface starts.The average convection flow velocity along the interface is high,even more than 0.025 m/s,depending on the droplet diameter,which facilitates the mass transfer.The Marangoni convection flow of the large droplet develops more easily than that of the small droplet,and the larger the droplet diameter is,the higher the convection flow velocity and the mass transfer rate are.Moreover,it is shown that the droplet diameter influences the impacting region of the Marangoni convection flow and its duration period.展开更多
Submerged arc welding process has been simulated to investigate the molten pool features of EH36 shipbuilding steel.One case only involved the surface tension model,and another one involved both the surface tension mo...Submerged arc welding process has been simulated to investigate the molten pool features of EH36 shipbuilding steel.One case only involved the surface tension model,and another one involved both the surface tension model and the interface tension model.The role of interface tension during welding is revealed,and the evolution of molten pool morphology is understood by comparing the surface temperature distribution,surface tension and interface tension distribution,and the streamline of the molten pool for the two cases.When the interface tension model is disregarded,a flow conducive to the outward expansion is formed in the surface area of the molten pool,resulting in a small weld depth-to-width ratio.After applying the interface tension model,the expanding outward flow is restrained,which leads to a deep penetration morphology with a large weld depth-to-width ratio due to the inward flow governed by the Marangoni forces.The simulation results involving the interface tension model have been verified with satisfactory predictability.展开更多
Fused ternary CaF_(2)–SiO_(2)–MnO fluxes have been manufactured and applied to join EH36 shipbuilding steel under high heat input submerged arc welding.Five fluxes have been designed to clarify the effect of MnO con...Fused ternary CaF_(2)–SiO_(2)–MnO fluxes have been manufactured and applied to join EH36 shipbuilding steel under high heat input submerged arc welding.Five fluxes have been designed to clarify the effect of MnO content in CaF_(2)–SiO_(2)–MnO flux on the impact toughness of the weld metal,with the added amount of MnO from 10 to 50 wt.%at the expense of CaF_(2).With the increase in MnO content,the Charpy impact energy increases first and then decreases,experiencing a maximum value at 30 wt.%MnO.Microstructure of the weld metals has also been studied to account for impact toughness variations.It has been demonstrated that the highest acicular ferrite volume fraction in the weld metal is achieved at 30 wt.%MnO,which is concurrent to the maximum value of Charpy impact energy.It is believed that the Mn and O content variations in the weld metal contribute synergistically to such an interesting phenomenon.展开更多
基金supported by the National Natural Science Foundation of China(51671052,51750110513,52250610222)the Fundamental Research Funds for the Central Universities(N182502042)the Liao Ning Revitilization Talents Program(XLYC1902105)。
文摘Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn pollutants.However,their utilization is hindered by high preparation costs,low yields,environmental pollution during synthesis,and challenges in regenerating the adsorbent.This study proposes a novel approach to address these limitations by developing nitrogen-doped three-dimensional(3D)polyvinyl alcohol(PVA)crosslinked graphene sponges(N-PGA)using a cross-linking method with ammonium carbonate.This method offers a relatively mild,environmentally friendly approach.Ammonium carbonate serves as both a reducing and modifying agent,facilitating the formation of the intrinsic structure of N-PGA and acting as a nitrogen source.Meanwhile,PVA is utilized as the cross-linking agent.The results demonstrate that N-PGA exhibits a favorable internal 3D hierarchical porous structure and possesses robust mechanical properties.The measured specific surface area(BET)of N-PGA was as high as406.538 m^(2)·g^(-1),which was favorable for its efficient adsorption of Congo red(CR)dye molecules.At an initial concentration of 50 mg·L^(-1),N-PGA achieved an impressive removal rate of 89.6%and an adsorption capacity of 112 mg·g^(-1)for CR dye.Furthermore,it retained 79%of its initial adsorption capacity after 10 cycles,demonstrating excellent regeneration performance.In summary,the synthesized N-PGA displays remarkable efficacy in the adsorption of CR dye in wastewater,opening up new possibilities for utilizing 3D porous graphene nanomaterials as efficient adsorbents in wastewater treatment.
基金the National Natural Science Foundation of China(Nos.52074078 and 52374327)the Applied Fundamental Research Program of Liaoning Province(No.2023JH2/101600002)+2 种基金the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group(No.KJBLM202202)the Fundamental Research Funds for the Central Universities(Nos.N2201023 and N2325009).
文摘Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.
基金supported by the National Natural Science Foundation of China (Nos.52174277 and 52204309)the China Postdoctoral Science Foundation (No.2022M720683).
文摘High-chromium vanadium-titanium magnetite(HVTM)is a crucial polymetallic-associated resource to be developed.The allpellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future.By referencing the production data of vanadium-titanium magnetite blast furnaces,this study explored the softening-melting behavior of high-chromium vanadium-titanium magnetite and obtained the optimal integrated burden based on flux pellets.The results show that the burden with a composition of 70wt%flux pellets and 30wt%acid pellets exhibits the best softening-melting properties.In comparison to that of the single burden,the softening-melting characteristic temperature of this burden composition was higher.The melting interval first increased from 307 to 362℃and then decreased to 282℃.The maximum pressure drop(ΔPmax)decreased from 26.76 to 19.01 kPa.The permeability index(S)dropped from 4643.5 to 2446.8 kPa·℃.The softening-melting properties of the integrated burden were apparently improved.The acid pellets played a role in withstanding load during the softening process.The flux pellets in the integrated burden exhibited a higher slag melting point,which increased the melting temperature during the melting process.The slag homogeneity and the TiC produced by over-reduction led to the gas permeability deterioration of the single burden.The segregation of the flux and acid pellets in the HVTM proportion and basicity mainly led to the better softening-melting properties of the integrated burden.
基金supported by the National Natural Science Foundation of China(Nos.52074086,51974073,52074072,52074074)the Fundamental Research Funds for the Central Universities,China(No.N2225039)the Liaoning Provincial Natural Science Foundation of China(No.2019-MS-132)。
文摘Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.
基金supported by the National Natural Science Foundation of China(Nos.52174277 and 51874077)the Fundamental Funds for the Central Universities,China(No.N2225032)+1 种基金the China Postdoctoral Science Foundation(No.2022M720683)the Postdoctoral Fund of Northeastern University,China。
文摘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–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) 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–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) diffusion couples.The regional boundaries of calcium and vanadium are easily identifiable for the CaO–V_(2)O_(5) diffusion couple.Meanwhile,for the MnO_(2)–V_(2)O_(5) diffusion couple,MnO_(2) gradually decomposes to form Mn_(2)O_(3),and vanadium diffuses into the interior of Mn_(2)O_(3).Only a part of vanadium combines with manganese to form the diffusion production layer.CaV_(2)O_(6) and MnV_(2)O_(6) are the interfacial reaction products of the CaO–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) diffusion couples,respectively,whose thicknesses are 39.85 and 32.13μm 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–V_(2)O_(5) diffusion couple is higher than that of the MnO_(2)–V_(2)O_(5) diffusion couple for the same roasting time,and the diffusion reaction between vanadium and calcium is easier than that between vanadium and manganese.
基金financially supported by the National Natural Science Foundation of China(No.52074078)the National Key R&D Program of China(No.2021YFC2901200)+4 种基金the Applied Fundamental Research Program of Liaoning Province(No.2023JH2/101600002)the Liaoning Provincial Natural Science Foundation of China(No.2022-YQ-09)the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program,China(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group,China(No.KJBLM202202)the Fundamental Research Funds for the Central Universities,China(Nos.N2201023,N2325009)。
文摘Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation,and the initial CO_(2)chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g.Moreover,the effect of Ca/Mg molar ratio on the morphology,structure,and CO_(2)chemisorption capacity of the calcium-based sorbents were investigated.The results show that the optimal Ca/Mg molar ratio of sorbent for CO_(2)capture was4.2:1,and the skeleton support effect of MgO in calcium-based sorbents was determined.Meanwhile,the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model.There were two processes of CO_(2)chemisorption,and the activation energy of the first stage(reaction control)was found to be lower than that of the second stage(diffusion control).
基金financially supported by the National Natural Science Foundation of China(No.51704068)the National Key Technologies R&D Program of China(No.2017YFC0805100)the Fundamental Research Funds for the Central Universities(No.N172504020)
文摘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.
基金financially supported by the National Natural Science Foundation of China (No. 51674069)the National Key R & D Program of China (No. 2017YFC0805100)
文摘For the control of surface defects in interstitial-free(IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. The results show that, at casting speeds of 0.8 and 1.0 m/min, a thin liquid mold flux layer forms and non-uniform floating of argon bubbles occurs, inducing the entrainment and subsequent entrapment of the liquid flux; fine inclusion particles of Al_2O_3 can also aggregate at the solidification front. At higher casting speeds of 1.4 and 1.6 m/min, the liquid mold flux can be entrained and carried deeper into the liquid steel pool because of strong level fluctuations of the liquid steel and the flux. The optimal casting speed is approximately 1.2 m/min, with the most favorable surface flow status and, correspondingly, the lowest number of inclusions near the slab surface.
基金financially supported by the National Natural Science Foundation of China (Nos.51774075 and52174307)Liao Ning Revitalization Talents Program,China(No.XLYC1802032)
文摘The effect of titanium content on the refinement of austenite grain size in as-cast peritectic carbon steel was investigated by fast directional solidification experiments with simulating the solidification and growth of surface and subsurface austenite in continuously cast slabs.Transmission electron microscope(TEM)and scanning electron microscope(SEM)were used to analyze the size and distribution of Ti(C,N)precipitates during solidification.Based on these results,the pinning pressure of Ti(C,N)precipitates on the growth of coarse columnar grains(CCGs)was studied.The results show that the austenite microstructure of as-cast peritectic carbon steel is mainly composed of the regions of CCGs and fine columnar grains(FCGs).Increasing the content of titanium reduces the region and the short axis of the CCGs.When the content of titanium is 0.09wt%,there is no CCG region.Dispersed microscale particles will firstly form in the liquid,which will decrease the transition temperature from FCGs to CCGs.The chain-like nanoscale Ti(C,N)will precipitate with the decrease of the transition temperature.Furthermore,calculations shows that the refinement of the CCGs is caused by the pinning effect of Ti(C,N)precipitates.
基金financially supported by the Special Funds for the National Natural Science Foundation of China(No.U1608254)the National Key R&D Program of China(No.2018YFC1902002)
文摘Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malachite reached the maximum and the particle size reached the minimum of 0.7–100 μm. Agglomeration occurred between mineral particles when the rotational speed was increased to 580 r/min in DPG.However, no agglomeration was observed among particles with sizes 0.4–3 μm in WIG. X-ray diffraction analysis showed that, at a 580 r/min rotational speed in DPG, the amorphization degree of malachite was 53.12%, whereas that in WIG was 71.40%, indicating that MA led to amorphization and distortion of crystal structures. In addition, in the Fourier transform infrared(FT-IR) spectra of activated malachite, the bands associated with –OH, CO_3^(2-)and metal lattice vibrations of Cu–O and Cu–OH were weakened, and a new H–O–H bending mode and peaks of gaseous CO_2 appeared, indicating that MA decreased the band energy, enhanced dihydroxylation, and increased the chemical reactivity of the malachite.Furthermore, the leaching behavior of copper ore was greatly improved by MA.
基金financially supported by the National Key R&D Program of China (No. 2018YFC1902004)the National Natural Science Foundation of China (No. U1608254)+1 种基金the Project for Guangdong Collaborative Innovation and Platform Environment Building (No. 2017B090904035)the Special Project for Key Laboratory of Guangdong Science and Technology Department, China (No. 2017B030314046)
文摘An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.
基金the National Natural Science Foundation of China(Nos.51874078,U1710257,U1202274,and 51764039)the Open Fund of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education)Northeastern University,China(No.NEMM2019004).
文摘Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.
基金financially supported by the Special Funds for the National Natural Science Foundation of China(No.U1608254)the Open Fund of State Key Laboratory of Comprehensive Utilization of Low-Grade Refractory Gold Ores(No.ZJKY2017(B)KFJJ01 and ZJKY2017(B)KFJJ02)。
文摘A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated.Mineralogical studies on the concentrate showed that very fine gold grains(<10μm)were encapsulated in pyrite and arsenopyrite,while the proportion of monomer gold was only 21%.The gold-bearing sample was identified as a high-sulfur fine-sized wrapped-type refractory gold concentrate.The gold leaching efficiency obtained by direct cyanidation was only 59.86%.After biooxidation pretreatment,the sulfide minerals were almost completely decomposed,92 wt%of the mineral particles of the biooxidation residue were decreased to<38μm,and the proportion of monomer gold in the biooxidation residue was over 86%.Meanwhile,the gold content in the biooxidation residue was enriched to 55.60 g/t,and the S,Fe,and As contents were reduced to approximately 19.8 wt%,6.97 wt%,and 0.13 wt%,respectively.Ammoniacal thiosulfate was used for gold extraction from the biooxidation residue of the refractory gold concentrate.The results showed that the optimal reagent conditions were 0.18 M thiosulfate,0.02 M copper(II),1.0 M ammonia,and 0.24 M sulfite.Under these conditions,a maximum gold leaching efficiency of 85.05%was obtained.
基金Sponsored by National Key Basic Research Program of China(2012CB626812)National Natural Science Foundation of China(51104039)Program for New Century Excellent Talents in University of Ministry of Education of China(NCET-11-0077)
文摘A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the model was validated by the SEM analysis of the industrial products.The type and amount of inclusions in solidification structure of 253 MA heat-resistant steel were predicted by the model,and the valuable results for the inclusions controlling in 253 MA steel were obtained.When the cerium addition increases,the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253 MA steel and the precipitation temperature of SiO2 and MnS decreases.The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2 S,Ce3S4,and MnS as the sulfur content increases.The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases.There is only a small quantity of inclusions containing cerium in 253 MA steel with high cleanliness,i.e.,low oxygen and sulfur contents.By contrast,a mass of SiO2,MnS and Ce2O2 S are formed in steel when the oxygen and sulfur contents are high enough.The condition that MnS precipitates in 253 MA steel is 1.2 w[O]+w[S]>0.01%and SiO2 precipitates when 2 w[O]+w[S]>0.017%(w[S]<0.005%)and w[O]>0.006%(w[S]>0.005%).
基金The present work was financially supported by the National Natural Science Foundation of China(Nos.52074207 and 51874081)Key Laboratory of Ecological Metallurgy of Multimetallic Mineral(Northeastern University)of Ministry of Education.
文摘The effects of different hot deformation amounts on the evolution of inclusion and microstructure in Ti-Zr deoxidized steel were studied by utilizing the Thermecmaster-Z hot simulation test machine,automatic scanning electron microscope equipped with energy-dispersive spectrometer,and electron backscattered diffraction.The results indicated that hot deformation amount has no significant effect on the number density of oxide,but the MnS that precipitated on the Ti-Zr oxide surface undergoes extension and breakage,resulting in the changes in oxide aspect ratio.Moreover,the fracture of nitride mainly occurs in the sample with the second pass deformation amount of 42.9%and 71.4%,and the degree of fragmentation of nitride is more serious with the deformation amount increasing.During the hot compression,sulfide undergoes breakage and extension,and with the second pass deformation amount increasing,the breakage and extension of sulfide present a periodic change.Finally,with the increase in hot compression amount,the ferrite types in microstructure change from acicular ferrite and bainitic ferrite to polygonal ferrite,and the ferrite grain size is refined.When the total deformation amount increases from 30%to 80%,the ferrite grain sizes of grain boundary with the misorientation of 4°and 15°decrease from 4.14 and 5.67μm to 3.47 and 4.40μm,respectively.However,when the total deformation amount increases to 80%,the harmful ferrite/pearlite banded structure appears in the micro structure.Refining ferrite grain size and avoiding harmful microstructure are the key for the optimization of hot compression process.
基金Project (2022YFC2904405) supported by the National Key Research and Development Program of ChinaProjects (22078055,52074083) supported by the National Natural Science Foundation of China。
基金supported by the National Natural Science Foundation of China(No.51974071)National Key Research and Development Program of China(No.2022YFB3705101)the Opening Project Fund of Materials Service Safety Assessment Facilities(No.MSAF-2021-009).
文摘Advancements in metallurgical technology have led to the emergence of high-performance requirements for metal materials,like high uniformity,high purity,and superfine crystallinity.This has resulted in the development and application of internal cooling source(ICS),vibrational,and vibrational internal cooling source methods in metal solidification processes to afford products with refined crystal grains and large proportions of equiaxed crystals.These methods have gradually been introduced into laboratories and some steel mills over the past few decades.However,there are few successful industrial applications of these methods,as there is no comprehensive understanding of their control theories and principles.Accordingly,the development,basic principles,and classifications of the three types of methods are summarized,and their impact on the solidification of molten metals and the morphology of solid products is discussed.In addition,experimental and numerical simulation-based researches on each type of method are reviewed and their prospects for applications are briefly discussed to control metal solidification.Finally,detailed future perspectives are provided on vibratory strip feeding,ICS,and pulsed magneto-oscillation methods.Hopefully,it will serve as a reference for future studies of the application of these and related methods in metal solidification processes.
基金funded by the National Natural Science Foundation of China(No.51904062)the Fundamental Research Funds of the Central Universities of China(No.N2225021)the Doctoral Scientific Research Foundation of Liaoning Institute of Science and Technology(No.2107B04).
文摘A mathematical model accounting for unsteady mass transfer across interface of a stationary iron droplet immersed into molten slag was established through the volume of fluid coupled with level set method.The Marangoni effect induced by mass transfer was reproduced successfully,and the hydrodynamic instability phenomena at the interface,such as the Marangoni convection flow,the evolution of the interfacial tension during the mass transfer,and the influence of Marangoni effect on the mass transfer rate,were revealed.The results show that the Marangoni convection flow develops quickly and behaves as an ordered structure in the forms of four pairs of the convection cell at the edge of the droplet once the oxygen transfer across the interface starts.The average convection flow velocity along the interface is high,even more than 0.025 m/s,depending on the droplet diameter,which facilitates the mass transfer.The Marangoni convection flow of the large droplet develops more easily than that of the small droplet,and the larger the droplet diameter is,the higher the convection flow velocity and the mass transfer rate are.Moreover,it is shown that the droplet diameter influences the impacting region of the Marangoni convection flow and its duration period.
基金The authors sincerely thank the National Natural Science Foundation of China(Grant Nos.U20A20277,52150610494,52104295,52011530180 and 52050410341)Research Fund for Central Universities(Grant Nos.N2125016 and N2025025)Young Elite Scientists Sponsorship Program by CAST(YESS)(Grant No.2021-2023QNRC001).
文摘Submerged arc welding process has been simulated to investigate the molten pool features of EH36 shipbuilding steel.One case only involved the surface tension model,and another one involved both the surface tension model and the interface tension model.The role of interface tension during welding is revealed,and the evolution of molten pool morphology is understood by comparing the surface temperature distribution,surface tension and interface tension distribution,and the streamline of the molten pool for the two cases.When the interface tension model is disregarded,a flow conducive to the outward expansion is formed in the surface area of the molten pool,resulting in a small weld depth-to-width ratio.After applying the interface tension model,the expanding outward flow is restrained,which leads to a deep penetration morphology with a large weld depth-to-width ratio due to the inward flow governed by the Marangoni forces.The simulation results involving the interface tension model have been verified with satisfactory predictability.
基金The authors sincerely thank the State Key Laboratory of Refractories and Metallurgy(Grant No.G202206)National Natural Science Foundation of China(Grant Nos.U20A20277 and 52150610494)National Key Research and Development Program of China(Grant No.2022YFE0123300).
文摘Fused ternary CaF_(2)–SiO_(2)–MnO fluxes have been manufactured and applied to join EH36 shipbuilding steel under high heat input submerged arc welding.Five fluxes have been designed to clarify the effect of MnO content in CaF_(2)–SiO_(2)–MnO flux on the impact toughness of the weld metal,with the added amount of MnO from 10 to 50 wt.%at the expense of CaF_(2).With the increase in MnO content,the Charpy impact energy increases first and then decreases,experiencing a maximum value at 30 wt.%MnO.Microstructure of the weld metals has also been studied to account for impact toughness variations.It has been demonstrated that the highest acicular ferrite volume fraction in the weld metal is achieved at 30 wt.%MnO,which is concurrent to the maximum value of Charpy impact energy.It is believed that the Mn and O content variations in the weld metal contribute synergistically to such an interesting phenomenon.
