Process metallurgy and data-driven prediction and feedback of blast furnace heat indicators

The prediction and control of furnace heat indicators are of great importance for improving the heat levels and conditions of the complex and difficult-to-operate hour-class delay blast furnace(BF)system.In this work,a prediction and feedback model of furnace heat indicators based on the fusion of data-driven and BF ironmaking processes was proposed.The data on raw and fuel materials,process op-eration,smelting state,and slag and iron discharge during the whole BF process comprised 171 variables with 9223 groups of data and were comprehensively analyzed.A novel method for the delay analysis of furnace heat indicators was established.The extracted delay variables were found to play an important role in modeling.The method that combined the genetic algorithm and stacking efficiently im-proved performance compared with the traditional machine learning algorithm in improving the hit ratio of the furnace heat prediction model.The hit ratio for predicting the temperature of hot metal in the error range of±10℃ was 92.4%,and that for the chemical heat of hot metal in the error range of±0.1wt%was 93.3%.On the basis of the furnace heat prediction model and expert experience,a feedback model of furnace heat operation was established to obtain quantitative operation suggestions for stabilizing BF heat levels.These sugges-tions were highly accepted by BF operators.Finally,the comprehensive and dynamic model proposed in this work was successfully ap-plied in a practical BF system.It improved the BF temperature level remarkably,increasing the furnace temperature stability rate from 54.9%to 84.9%.This improvement achieved considerable economic benefits.

Effect of titanium on the sticking of pellets based on hydrogen metallurgy shaft furnace:Behavior analysis and mechanism evolution

Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pellets occurs due to the aggregation of metal-lic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation.This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions.Results showed that the sticking index(SI)decreased linearly with the increasing TiO2 addition.This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction,leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface.When the TiO2 addition amount was raised from 0 to 15wt%at 1100°C,the SI also increased from 0.71%to 59.91%.The connection of the slag phase could be attributed to the sticking at a low reduction temperature,corresponding to the low sticking strength.Moreover,the interconnection of metallic iron became the dominant factor,and the SI increased sharply with the increase in re-duction temperature.TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.

Progress,challenges,and prospects of spent lithium-ion batteries recycling:A review

The recycling and reutilization of spent lithium-ion batteries(LIBs)have become an important measure to alleviate problems like resource scarcity and environmental pollution.Although some progress has been made,battery recycling technology still faces challenges in terms of efficiency,effectiveness and environmental sustainability.This review aims to systematically review and analyze the current status of spent LIB recycling,and conduct a detailed comparison and evaluation of different recycling processes.In addition,this review introduces emerging recycling techniques,including deep eutectic solvents,molten salt roasting,and direct regeneration,with the intent of enhancing recycling efficiency and diminishing environmental repercussions.Furthermore,to increase the added value of recycled materials,this review proposes the concept of upgrading recycled materials into high value-added functional materials,such as catalysts,adsorbents,and graphene.Through life cycle assessment,the paper also explores the economic and environmental impacts of current battery recycling and highlights the importance that future recycling technologies should achieve a balance between recycling efficiency,economics and environmental benefits.Finally,this review outlines the opportunities and challenges of recycling key materials for next-generation batteries,and proposes relevant policy recommendations to promote the green and sustainable development of batteries,circular economy,and ecological civilization.

Effect of electrical parameters and slag system on macrostructure of electroslag ingot

To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.

In-situ coating and surface partial protonation co-promoting performance of single-crystal nickel-rich cathode in all-solid-state batteries

The poor electrochemical performance of all-solid-state batteries(ASSBs),which is assemblied by Ni-rich cathode and poly(ethylene oxide)(PEO)-based electrolytes,can be attributed to unstable cathodic interface and poor crystal structure stability of Ni-rich cathode.Several coating strategies are previously employed to enhance the stability of the cathodic interface and crystal structure for Ni-rich cathode.However,these methods can hardly achieve simplicity and high efficiency simultaneously.In this work,polyacrylic acid(PAA)replaced traditional PVDF as a binder for cathode,which can achieve a uniform PAA-Li(LixPAA(0<x≤1))coating layer on the surface of single-crystal LiNi_(0.83)Co_(0.12)Mn_(0.05)O_(2)(SC-NCM83)due to H^(+)/Li^(+)exchange reaction during the initial charging-discharging process.The formation of PAA-Li coating layer on cathode can promote interfacial Li^(+)transport and enhance the stability of the cathodic interface.Furthermore,the partially-protonated surface of SC-NCM83 casued by H^(+)/Li^(+)exchange reaction can restrict Ni ions transport to enhance the crystal structure stability.The proposed SC-NCM83-PAA exhibits superior cycling performance with a retention of 92%compared with that(57.3%)of SC-NCM83-polyvinylidene difluoride(PVDF)after 200 cycles.This work provides a practical strategy to construct high-performance cathodes for ASSBs.

High-chromium vanadium-titanium magnetite all-pellet integrated burden optimization and softening-melting behavior based on flux pellets

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.

Effects of iron oxide on crystallization behavior and spatial distribution of spinel in stainless steel slag

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%.

Efficient Preparation and Electrochemical Properties of BiOCl/Graphite by One-step Solvothermal Method

We used the surface-pretreated graphite paper(Gp)as a carrier and loaded BiOCl with high selectivity to Cl^(-)on its surface by solvothermal method to form BiOCl@Gp electrode.The morphology,structure,and composition of the materials were characterized by scanning electron microscopy and nitrogen adsorption/desorption,and the results showed that the spherical BiOCl particles were uniformly dispersed on the surface of the Gp,forming a mesoporous BiOCl@Gp composite with a specific surface area of 22.82 m^(2)/g and a pore volume of 0.043 cm3/g.Furthermore,cyclic voltammetry and electrochemical impedance spectroscopy were used to test the electrochemical properties of the composites,and the stability of BiOCl and the high conductivity of Gp were synergistic,the BiOCl@Gp exhibited a specific capacitance of 30.2 F·g^(-1) at a current density of 0.5 A·g^(-1),and the selectivity of the BiOCl@Gp materials for Cl^(-)was significantly higher than that of SO_(4)^(2-),NO_(2)^(-),and HCO_(3)^(-).Therefore,BiOCl@Gp composite electrode materials can be used for the selective adsorption of Cl^(-)in wastewater,in order to achieve efficient wastewater recycling.

Solvothermal synthesis and adsorption performance of layered boehmite using aluminum chloride and high-alumina fly ash

High alumina fly ash(FAHAl)is a kind of bulk solid waste unique to China,whose availability of high-value aluminum and the threat to the environment makes its high-value utilization urgent.In this work,the alumina containing leaching solution obtained from Na_(2)CO_(3) roasting and HCl leaching of FAHAl was used as the mother liquor to prepare layered boehmite in situ.The preparation process with AlCl_(3) as the raw material was also compared.The formation process and mechanism of boehmite,the choice of solvent,along with the adsorption capability of Congo red were analyzed by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,Brunauer-Emmett-Teller method and adsorption experiments.Results showed that during the preparation of layered boehmite,the precursor Al(OH)_(3) from the reaction of Al^(3+) and OH-is transformed into boehmiteγ-AlOOH.The existence of ethanol is beneficial to regulate and promote the growth of boehmite crystal effectively.When water and ethanol are mixed with a volume ratio of 2:1 and used as the solvent,the maximum specific surface area of the boehmite is obtained at 135.7 m^(2)·g^(-1),and 99.16%of Congo red can be absorbed after 10 min when AlCl3 is used as a raw material.As purified leaching solution is used as the mother liquid,the crystallinity of boehmite decreases slightly when the pH value decreases from 12.5 to 11.When pH is 11,the removal efficiency of Congo red reaches a maximum of 72.25%.This process not only achieves the extraction of aluminum and high-value utilization of FAHAl but also provides a thought to prepare layered boehmite with adsorption properties.

Interaction mechanism of cyanide with pyrite during the cyanidation of pyrite and the decyanation of pyrite cyanide residues by chemical oxidation

The toxic cyanides in cyanide residues produced from cyanidation process for gold extraction are harmful to the environment.Pyrite is one of the main minerals existing in cyanide residues.In this work,the interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue were analyzed.Results revealed that high pH value,high cyanide concentration,and high pyrite dosage promoted the interaction of cyanide with pyrite.The cyanidation of pyrite was pseudo-second-order with respect to cyanide.The decyanation of pyrite cyanide residue by Na_(2)SO_(3)/air oxidation was performed.The cyanide removal efficiency was 83.9% after 1 h of reaction time under the optimal conditions of pH value of 11.2,SO_(3)^(2-) dosage of 22 mg·g^(-1),and air flow rate of 1.46 L·min^(-1).X-ray photoelectron spectroscopy analysis of the pyrite samples showed the formation of Fe(Ⅲ)and FeSO_(4) during the cyanidation process.The cyanide that adsorbed on the pyrite surface after cyanidation mainly existed in the forms of free cyanide(CN^(-))and ferrocyanide(Fe(CN)_(6)^(4-)),which were effectively removed by Na_(2)SO_(3)/air oxidation.During the decyanation process,air intake promoted pyrite oxidation and weakened cyanide adsorption on the pyrite surface.This study has practical significance for gold enterprises aiming to mitigate the environmental impact related to cyanide residues.

Oxidation behavior of FeV_(2)O_(4)and FeCr_(2)O_(4)particles in the air:Nonisothermal kinetic and reaction mechanism

High-temperature oxidation behavior of ferrovanadium(FeV_(2)O_(4))and ferrochrome(FeCr_(2)O_(4))spinels is crucial for the application of spinel as an energy material,as well as for the clean usage of high-chromium vanadium slag.Herein,the nonisothermal oxidation behavior of FeV_(2)O_(4)and FeCr_(2)O_(4)prepared by high-temperature solid-state reaction was examined by thermogravimetry and X-ray diffraction(XRD)at heating rates of 5,10,and 15 K/min.The apparent activation energy was determined by the Kissinger-Akahira-Sunose(KAS)method,whereas the mechanism function was elucidated by the Malek method.Moreover,in-situ XRD was conducted to deduce the phase transformation of the oxidation mechanism for FeV_(2)O_(4)and FeCr_(2)O_(4).The results reveal a gradual increase in the overall apparent activation energies for FeV_(2)O_(4)and FeCr_(2)O_(4)during oxidation.Four stages of the oxidation process are observed based on the oxidation conversion rate of each compound.The oxidation mechanisms of FeV_(2)O_(4)and FeCr_(2)O_(4)are complex and have distinct mechanisms.In particular,the chemical reaction controls the entire oxidation process for FeV_(2)O_(4),whereas that for FeCr_(2)O_(4)transitions from a three-dimensional diffusion model to a chemical reaction model.According to the in-situ XRD results,numerous intermediate products are observed during the oxidation process of both compounds,eventually resulting in the final products FeVO_(4)and V2O_(5)for FeV_(2)O_(4)and Fe_(2)O_(3)and Cr_(2)O_(3)for FeCr_(2)O_(4),respectively.

Effect of phosphorus content on interfacial heat transfer and film deposition behavior during the high-temperature simulation of strip casting

The interfacial wettability and heat transfer behavior are crucial in the strip casting of high phosphorus-containing steel.A hightemperature simulation of strip casting was conducted using the droplet solidification technique with the aims to reveal the effects of phosphorus content on interfacial wettability,deposited film,and interfacial heat transfer behavior.Results showed that when the phosphorus content increased from 0.014wt%to 0.406wt%,the mushy zone enlarged,the complete solidification temperature delayed from1518.3 to 1459.4℃,the final contact angle decreased from 118.4°to 102.8°,indicating improved interfacial contact,and the maximum heat flux increased from 6.9 to 9.2 MW/m2.Increasing the phosphorus content from 0.081wt%to 0.406wt%also accelerated the film deposition rate from 1.57 to 1.73μm per test,resulting in a thickened naturally deposited film with increased thermal resistance that advanced the transition point of heat transfer from the fifth experiment to the third experiment.

Effect of microalloying on wettability and interface characteristics of Zr-based bulk metallic glasses with W substrate

The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of the wettability and interface characteristics between the reinforcing phase and the bulk metallic glasses(BMGs).This work optimized the composition of Zr-based BMGs through microalloying methods,resulting in a new set of Zr-based BMGs with excellent glass-forming ability.Wetting experiments between the Zr-based BMGs melts and W substrates were conducted using the traditional sessile drop method,and the interfaces were characterized utilizing a scanning electron microscope(SEM)equipped with energy dispersive X-ray spectroscopy(EDS).The work demonstrates that the microalloying method substantially enhances the wettability of the Zr-based BMGs melt.Additionally,the incorporation of Nb element impedes the formation of W-Zr phases,but the introduction of Nb element does not alter the extent of interdiffusion between the constituent elements of the amorphous matrix and W element,indicating that the influence of Nb element on the diffusion of individual elements is minute.

Synthesis of crystalline g-C_(3)N_(4) with rock/molten salts for efficient photocatalysis and piezocatalysis

Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications.Currently,synthesizing highly crystalline g-C_(3)N_(4) with sufficient surface activities still remains challenging.Herein,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed salts.The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation.Intriguingly,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt methods.These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.

Trace Cobalt Doping and Defect Engineering of High Surface Area α-Ni(OH)_(2) for Electrocatalytic Urea Oxidation

Owing to the intrinsically sluggish kinetics of urea oxidation reaction(UOR)involving a six-electron transfer process,developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed.Herein,by taking advantage of 2-Methylimidazole,of which is a kind of alkali in water and owns strong coordination ability to Co^(2+)in methanol,trace Co(1.0 mol%)addition was found to induce defect engineering onα-Ni(OH)_(2)in a dual-solvent system of water and methanol.Physical characterization results revealed that the synthesized electrocatalyst(WM-Ni_(0.99)Co_(0.01)(OH)_(2))was a kind of defective nanosheet with thickness around 5-6 nm,attributing to the synergistic effect of Co doping and defect engineering,its electron structure was finely altered,and its specific surface a rea was tremendously enlarged from 68 to 172.3 m^(2)g^(-1).With all these merits,its overpotential to drive 10 mA cm^(-2)was reduced by 110 mV.Besides,the interfacial behavior of UOR was also well deciphered by operando electrochemical impedance spectroscopy.

Comparison of the effects of Ti-and Si-containing minerals on goethite transformation in the Bayer digestion of goethitic bauxite

Goethitic bauxite is a widely used raw material in the alumina industry.It is an essential prerequisite to clarify the effect of Ti-and Si-containing minerals on goethite transformation in the Bayer digestion process,which could efficiently utilize the Fe-and Al-containing minerals present in goethitic bauxite.In this work,the interactions between anatase or kaolinite with goethite during various Bayer digestion processes were investigated using X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),transmission electron microscopy (TEM),and scanning electron microscopy (SEM).The results showed that anatase and kaolinite hindered the transformation of goethite.Anatase exerted more significant effects than kaolinite due to the dense sodium titanate layer on the goethite surface after reacting with the sodium aluminate solution.Adding the reductant hydrazine hydrate could eliminate the retarding effect by inducing the transformation of goethite into magnetite.In this process,titanium was embedded into the magnetite lattice to form Ti-containing magnetite.Furthermore,the weakening of the interaction between magnetite and sodium aluminosilicate hydrate reduced the influence of kaolinite.As a validation of the above results,the reductive Bayer method resulted in the transformation of goethite into goethitic bauxite with 98.87% relative alumina digestion rate.The obtained red mud with 72.99wt% Fe2O3could be further utilized in the steel industry.This work provides a clear understanding of the transformative effects of Ti-and Si-containing minerals on iron mineral transformation and aids the comprehensive use of iron and aluminum in goethitic bauxite subjected to the reductive Bayer method.

Flow and penetration behavior of submerged side-blown gas

To assess the widely used submerged side-blowing in pyrometallurgy,a high-speed camera-digital image processing-statistical approach was used to systematically investigate the effects of the gas flow rate,nozzle diameter,and inclination angle on the space-time distribution and penetration behavior of submerged side-blown gas in an air-water system.The results show that the gas motion gradually changes from a bubbling regime to a steady jetting regime and the formation of a complete jet structure as the flow rate increases.When the flow rate is low,a bubble area is formed by large bubbles in the area above the nozzle.When the flow rate and the nozzle diameter are significant,a bubble area is formed by tiny bubbles in the area above the nozzle.The increased inclination angle requires a more significant flow rate to form a complete jet structure.In the sampling time,the dimensionless horizontal and vertical penetration depths are Gaussian distributed.Decreasing the nozzle diameter and increasing the flow rate or inclination angle will increase the distribution range and discreteness.New correlations for a penetration depth with an error of±20%were obtained through dimensional analysis.The dimensionless horizontal penetration depth of an argon-melt system in a 120 t converter calculated by the correlation proposed by the current study is close to the result calculated by a correlation in the literature and a numerical simulation result in the literature.

Combustion performance of pulverized coal and corresponding kinetics study after adding the additives of Fe_(2)O_(3) and CaO

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.

Kinetics of austenite growth and bainite transformation during reheating and cooling treatments of high strength microalloyed steel produced by sub-rapid solidification

First,strip cast samples of high strength microalloyed steel with sub-rapid solidification characteristics were prepared by simulated strip casting technique.Next,the isothermal growth of austenite grain during the reheating treatment of strip casts was observed in situ through confocal laser scanning microscope(CLSM).The results indicated that the time exponent of grains growth suddenly rise when the isothermal temperature higher than 1000℃.And the activation energy for austenite grain growth were calculated to be 538.0 kJ/mol in the high temperature region(above 1000℃)and 693.2 kJ/mol in the low temperature region(below 1000℃),respectively.Then,the kinetics model of austenite isothermal growth was established,which can predict the austenite grain size during isothermal hold very well.Besides,high density of second phase particles with small size was found during the isothermal hold at the low temperature region,leading to the refinement of austenite grain.After isothermal hold at different temperature for 1800 s,the bainite transformation in microalloyed steel strip was also observed in situ during the continuous cooling process.And growth rates of bainite plates with different nucleation positions and different prior austenite grain size(PAGS)were calculated.It was indicated that the growth rate of the bainite plate is not only related to the nucleation position but also to the PAGS.

Comparison of the interface reaction behaviors of CaO–V_(2)O_(5) and MnO_(2)–V_(2)O_(5) solid-state systems based on the diffusion couple method

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.