Since photo-induced polymerization of the ultra-violet(UV)-curing adhesive from a fluid state to a solid state is an exothermic process,the UV curing exothermic behavior can be regarded as a potential evaluation metho...Since photo-induced polymerization of the ultra-violet(UV)-curing adhesive from a fluid state to a solid state is an exothermic process,the UV curing exothermic behavior can be regarded as a potential evaluation methodology to analyze UV-curing kinetics.Herein,a fiber Bragg grating(FBG)-based UV curing exothermic behavior monitoring is proposed to evaluate the UV-curing dynamic process and analyze a series of thermal and mechanical properties changes during curing.The exothermic behavior of the UV curing adhesive during curing and the feasibility of FBG-based curing kinetic analysis scheme are verified experimentally,full cycle cure monitoring of the UV curing adhesive can be realized by this FBG-based curing kinetic analysis scheme,and the UV-curing kinetics of four different types of the UV curing adhesive are corresponding to different exothermic behaviors.Compared with curing process evaluation based on refractive index variation,this FBG-based exothermic behavior monitoring has the ability to extract more details of the curing process,and some curing stages with negligible refractive index changes also can be distinguished.By using this proposed scheme,the UV-curing dynamic process and multiple characteristic parameters,such as curing time,time constant,transient temperature rise,and residual stress,can be evaluated,which may contribute to evaluating and analyzing UV-curing kinetics more comprehensively.展开更多
Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting t...Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.展开更多
This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,5...This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.展开更多
In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodyn...In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.展开更多
Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment ...Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.展开更多
This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that ...This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.展开更多
Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Bori...Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.展开更多
Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batterie...Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.展开更多
Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cok...Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.展开更多
The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and h...The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.展开更多
Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and init...Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.展开更多
Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its prac...Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its practical application in emerging Zn based batteries.Unexpectedly,here we discover a Zn‖organic battery with exceptional kinetics properties enabled by a hydrated DES electrolyte,which can render higher discharge capacity,smaller voltage polarization,and faster kinetics of charge transfer in comparison with conventional aqueous 3 M ZnCl_(2)electrolyte,though its viscosity is two orders of magnitude higher than the latter.The improved kinetics of charge transfer and ion diffusion is demonstrated to originate from the local electron structure regulation of cathode in hydrated DES electrolyte.Furthermore,the DES electrolyte has also been shown to restrict parasitic reaction associated with active water by preferential urea-molecular adsorption on Zn surface and stronger water trapping in solvation structure,giving rise to long-term stable dendrite-free Zn plating/stripping.This work provides a new rationale for understanding electrochemical behaviors of organic cathodes in DES electrolyte,which is conducive to the development of high-performance Zn‖organic batteries.展开更多
Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully u...Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.展开更多
The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical r...The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.展开更多
Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from...Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.展开更多
The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains f...The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains fundamentally challenging due to competing overhydrogenation.Here we report an atomic-scale approach for encapsulating ultrafine PtCu(Platinum,Copper)bimetallic nanoclusters(NCs)within the microporous TS-1 zeolite matrix through a ligand-as sis ted hydrothermal strategy.Remarkably,the as-synthesized PtCu@TS-1 catalyst exhibited an unprecedented turnover frequency(TOF)of 2006.7 h^(-1)and a superior styrene yield of 87.7%,significantly surpassing conventional Pt-based catalysts.Advanced characterization and in situ spectroscopy revealed that electron-rich Pt sites,induced by electron transfer from Cu in confined PtCu ensembles,substantially lower the activation barrier for hydrogen dissociation,accelerating selective hydrogenation.Moreover,the atomic confinement effect within the zeolite structure effectively modulates intermediate adsorption and accelerates product desorption,thus overcoming the selectivity-activity tradeoff.This study introduces a generalizable atomic-level catalyst design principle,highlighting the immense potential of quantum-sized bimetallic clusters within porous materials for precisely tuning reaction selectivity and activity.展开更多
Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.I...Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).展开更多
Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can in...Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.展开更多
Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxi...Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxidation leaching process with H_(2)SO_(4) and H_(2)O_(2).The experimental results showed that under the optimum conditions,the contents of selenium,tellurium,and copper in the SDS were reduced from 22.13 wt%,3.58 wt%,and 6.42 wt%to 3.06 wt%,0.27 wt%,and 0.33 wt%,respectively.Correspondingly,the recovery rates are 87.08%,97.15%and 99.7%.The leaching processes of selenium and tellurium were controlled by diffusion and chemical reactions,and the leaching behavior of copper was controlled by chemical reactions.Below 45℃,the activation energies for selenium,tellurium,and copper were found to be 26.47,62.18 and 19.67 kJ/mol,respectively.In addition,the contents of lead,silver and gold in the leaching residue are increased to 46.8 wt%,8.35 wt%and 0.27 wt%,respectively.These substances can be utilized as raw materials for the recovery of these valuable metals.Importantly,the entire process does not generate toxic or harmful waste,making it a green and environmentally friendly method for resource recovery.展开更多
As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limoni...As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limonite was explored.The micromorphology,microstructure,and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope,an automatic surface area and porosity analyzer,an X-ray diffractometer,and a vibrating sample magnetometer.Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate.Microwave fluidization roasting significantly increased the specific surface area of limonite,increased the opportunity of contact between CO and limonite,and accelerated the transformation from FeO(OH)toα-Fe_(2)O_(3)and then to Fe_(3)O_(4).In addition,the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity,which has a certain activation effect on the reduction roasting of limonite.The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m^(2)·kg^(-1)and 2.50×10^(-4)m^(3)·kg^(-1),respectively.The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt%and a recovery of 90.07wt%.Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model(G(α)=α^(2)),with the mechanism function described as k=0.08208exp[-20.3441/(R_(g)T)].Therefore,microwave fluidization roasting shows significant potential in the beneficiation of limonite,offering a promising approach for the exploitation of refractory iron ores.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62275039 and 61705189)Fundamental Research Funds for the Central Universities,China(Grant No.DUT24MS022)State Key Laboratory of Advanced Optical Communication Systems and Networks,China(Grant No.2022GZKF001).
文摘Since photo-induced polymerization of the ultra-violet(UV)-curing adhesive from a fluid state to a solid state is an exothermic process,the UV curing exothermic behavior can be regarded as a potential evaluation methodology to analyze UV-curing kinetics.Herein,a fiber Bragg grating(FBG)-based UV curing exothermic behavior monitoring is proposed to evaluate the UV-curing dynamic process and analyze a series of thermal and mechanical properties changes during curing.The exothermic behavior of the UV curing adhesive during curing and the feasibility of FBG-based curing kinetic analysis scheme are verified experimentally,full cycle cure monitoring of the UV curing adhesive can be realized by this FBG-based curing kinetic analysis scheme,and the UV-curing kinetics of four different types of the UV curing adhesive are corresponding to different exothermic behaviors.Compared with curing process evaluation based on refractive index variation,this FBG-based exothermic behavior monitoring has the ability to extract more details of the curing process,and some curing stages with negligible refractive index changes also can be distinguished.By using this proposed scheme,the UV-curing dynamic process and multiple characteristic parameters,such as curing time,time constant,transient temperature rise,and residual stress,can be evaluated,which may contribute to evaluating and analyzing UV-curing kinetics more comprehensively.
基金Supported by Innovation Capability Support Program of Shaanxi(2024RS-CXTD-53,2024ZC-KJXX-096)the Key R&D Program of Shaanxi Province(2022QCY-LL-69)Xi’an Science and Technology Project(24GXFW0089)。
文摘Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.
文摘This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.
基金financially supported by the National Natural Science Foundation of China(No.52174342)Beijing Natural Sci-ence Foundation(No.2232044)Beijing Municipal Education Commission Research Plan General Project(No.KM202410005009).
文摘In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.
基金supported by the National Natural Science Foundation of China(U22A20120,52071135,51871090,U1804135,and 52301269)the Natural Science Foundation of Hebei Province for Innovation Groups Program(C2022203003)Fundamental Research Funds for the Universities of Henan Province(NSFRF220201).
文摘Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.
基金supported by the National Natural Science Foundation of China(No.52271089)the financial support from the C hina Postdoctoral Science Foundation(No.2023M732192)。
文摘This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.
文摘Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.
基金National Key R&D Program of China,Grant/Award Number:2023YFB2503900National Natural Science Foundation of China,Grant/Award Number:12172143Shenzhen Science and Technology Program,Grant/Award Numbers:JCYJ20220818100418040,JCYJ20220530160816038。
文摘Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.
基金supported by National Natural Science Foundation of China(22178002,22178001)Natural Science Foundation of Anhui Province(2308085Y19)Excellent Youth Research Project of Anhui Provincial Department of Education(2022AH030045).
文摘Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.
基金supported by the National Natural Science Foundation of China(No.22276064)the Youth Innovation Grant of Xiamen,Fujian Province(No.3502Z20206006)+1 种基金the MOE Key Laboratory of Resources and Environmental System Optimization(No.KLRE-KF202205)Fujian Science and Technology Project(No.2022Y3007).
文摘The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.
基金National Natural Science Foundation of China(52275328,51875157)。
文摘Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.
基金financial support from the National Natural Science Foundation of China(NSFC No.52202253,52072173)Natural Science Foundation of Jiangsu Province(No.BK20220914)+1 种基金Fundamental Research Funds for the Central Universities(No.ILA22061,ILA22075)Large Instrument and Equipment Sharing Fund of NUAA.
文摘Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its practical application in emerging Zn based batteries.Unexpectedly,here we discover a Zn‖organic battery with exceptional kinetics properties enabled by a hydrated DES electrolyte,which can render higher discharge capacity,smaller voltage polarization,and faster kinetics of charge transfer in comparison with conventional aqueous 3 M ZnCl_(2)electrolyte,though its viscosity is two orders of magnitude higher than the latter.The improved kinetics of charge transfer and ion diffusion is demonstrated to originate from the local electron structure regulation of cathode in hydrated DES electrolyte.Furthermore,the DES electrolyte has also been shown to restrict parasitic reaction associated with active water by preferential urea-molecular adsorption on Zn surface and stronger water trapping in solvation structure,giving rise to long-term stable dendrite-free Zn plating/stripping.This work provides a new rationale for understanding electrochemical behaviors of organic cathodes in DES electrolyte,which is conducive to the development of high-performance Zn‖organic batteries.
基金supported by the National Key Research&Development Program of China(2021YFB3803200)the National Natural Science Foundation of China(22288102).
文摘Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.
基金National Key Research and Development Program of China(No.2022YFC2904900)the National Natural Science Foundation of China(No.U1902221).
文摘The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.
基金support from the National Natural Science Foundation of China(No.52174300)Natural Science Foundation of Chongqing,China(Nos.cstc2020jcyj-msxmX0583 and cstc2021jcyj-msxmX1004)+1 种基金Chongqing Talent Plan Project(No.cstc2021ycjh-bgzxm0211)Chongqing Doctoral"Through Train"Project(No.sl202100000343).T。
文摘Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.
基金financially supported by the Taishan Scholar Program of Shandong Province(No.tsqn202408211)China Postdoctoral Science Foundation(No.2024M761141)+3 种基金Postdoctoral Fellowship Program of CPSF(No.GZC20250785)Postdoctoral Innovation Program of Shandong Province(No.SDCX-ZG-202503085)Shandong Excellent YoungScientists Fund Program(No.2022HWYQ-082)National Natural Science Foundation of China(Nos.22278174,21808079,and 22378159)
文摘The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains fundamentally challenging due to competing overhydrogenation.Here we report an atomic-scale approach for encapsulating ultrafine PtCu(Platinum,Copper)bimetallic nanoclusters(NCs)within the microporous TS-1 zeolite matrix through a ligand-as sis ted hydrothermal strategy.Remarkably,the as-synthesized PtCu@TS-1 catalyst exhibited an unprecedented turnover frequency(TOF)of 2006.7 h^(-1)and a superior styrene yield of 87.7%,significantly surpassing conventional Pt-based catalysts.Advanced characterization and in situ spectroscopy revealed that electron-rich Pt sites,induced by electron transfer from Cu in confined PtCu ensembles,substantially lower the activation barrier for hydrogen dissociation,accelerating selective hydrogenation.Moreover,the atomic confinement effect within the zeolite structure effectively modulates intermediate adsorption and accelerates product desorption,thus overcoming the selectivity-activity tradeoff.This study introduces a generalizable atomic-level catalyst design principle,highlighting the immense potential of quantum-sized bimetallic clusters within porous materials for precisely tuning reaction selectivity and activity.
基金financially supported by the National Natural Science Foundation of China(Nos.52204331 and 52374315)the Major Industrial Innovation Plan of Anhui Provincial Development and the Reform Commission,China(No.AHZDCYCX-LSDT2023-01)。
文摘Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).
基金financially supported by the Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking (No. KF-20-3)Shandong Postdoctoral Science Foundation, China (No. SDCX-ZG-202301014)。
文摘Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.
基金Project(2022YFC2904900) supported by the National Key Research and Development Program of ChinaProject(U1902221) supported by the National Natural Science Foundation of China。
文摘Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxidation leaching process with H_(2)SO_(4) and H_(2)O_(2).The experimental results showed that under the optimum conditions,the contents of selenium,tellurium,and copper in the SDS were reduced from 22.13 wt%,3.58 wt%,and 6.42 wt%to 3.06 wt%,0.27 wt%,and 0.33 wt%,respectively.Correspondingly,the recovery rates are 87.08%,97.15%and 99.7%.The leaching processes of selenium and tellurium were controlled by diffusion and chemical reactions,and the leaching behavior of copper was controlled by chemical reactions.Below 45℃,the activation energies for selenium,tellurium,and copper were found to be 26.47,62.18 and 19.67 kJ/mol,respectively.In addition,the contents of lead,silver and gold in the leaching residue are increased to 46.8 wt%,8.35 wt%and 0.27 wt%,respectively.These substances can be utilized as raw materials for the recovery of these valuable metals.Importantly,the entire process does not generate toxic or harmful waste,making it a green and environmentally friendly method for resource recovery.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2901000)the National Natural Science Foundation of China(No.52104249)+1 种基金the Liaoning Joint Fund General Support Program Project(No.2023-MSBA-126)the Fundamental Research Funds for the Central Universities(No.N2401019)。
文摘As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limonite was explored.The micromorphology,microstructure,and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope,an automatic surface area and porosity analyzer,an X-ray diffractometer,and a vibrating sample magnetometer.Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate.Microwave fluidization roasting significantly increased the specific surface area of limonite,increased the opportunity of contact between CO and limonite,and accelerated the transformation from FeO(OH)toα-Fe_(2)O_(3)and then to Fe_(3)O_(4).In addition,the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity,which has a certain activation effect on the reduction roasting of limonite.The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m^(2)·kg^(-1)and 2.50×10^(-4)m^(3)·kg^(-1),respectively.The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt%and a recovery of 90.07wt%.Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model(G(α)=α^(2)),with the mechanism function described as k=0.08208exp[-20.3441/(R_(g)T)].Therefore,microwave fluidization roasting shows significant potential in the beneficiation of limonite,offering a promising approach for the exploitation of refractory iron ores.
