Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate ...Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.展开更多
The iron and steel industry,standing as a quintessential manufacture example with high consumption,pollution and emissions,faces significant environmental and sustainable development challenges.Electric arc furnace(EA...The iron and steel industry,standing as a quintessential manufacture example with high consumption,pollution and emissions,faces significant environmental and sustainable development challenges.Electric arc furnace(EAF)steelmaking process mainly uses scrap as raw material and is characterized by environmentally friendly and recyclable process.However,the further development of EAF route in China is limited by the reserve,supply,availability and quality of scrap resource.Direct reduced iron(DRI)is one of typical low-carbon and clean charges,which can effectively make up for the adverse effects caused by the lack of scrap.The physical and chemical properties,classifications,and production technologies of DRI are firstly reviewed.In particular,the reducing gas types,reduction temperature,and reduction mechanism of the DRI production with gas-based shaft furnace(SF)technology are detailed.Considering the crucial role played by DRI application in EAF,the influences of DRI addition on EAF smelting rules and operations including the blending and charging process,heat transfer and melting in molten bath,slag formation operation,refractory corrosion,and slag system evolution are then further discussed.Finally,the comparative analysis and assessment of the consumption level of material and energy as well as the cleaner production both covering the clean chemical composition of molten steel and the clean environment impact in EAF steelmaking with DRI charged are conducted.From perspectives of metallurgical process engineering,a suitable route of hydrogen generation and application(from coke oven gas,methanol,and clean energy power),CO_(2) capture and utilization integrated with SF–EAF process is proposed.In view of the difficulties in large-scale DRI application in EAF,the follow-up work should focus on the investigation of DRI charging and melting,slag system evolution and molten pool reaction rules,as well as the developments of the DRI standardized use technology and intelligent batching and control models.展开更多
Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized...Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.展开更多
Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly u...Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.展开更多
Blast furnace gas(BFG)is an important by-product energy for the iron and steel industry and has been widely used for heating or electricity generation.However,the undesirable contaminants in BFG(especially H_(2)S)gene...Blast furnace gas(BFG)is an important by-product energy for the iron and steel industry and has been widely used for heating or electricity generation.However,the undesirable contaminants in BFG(especially H_(2)S)generate harmful environmental emissions.The desulfurization of BFG is urgent for integrated steel plants due to the stringent ultra-low emission standards.Compared with other desulfurization materials,zeolite-based adsorbents represent a viable option with low costs and long service life.In this study,an ammonia-induced CuO modified 13X adsorbent(NH_(3)–CuO/13X)was prepared for H_(2)S removal from simulated BFG at low temperature.The XRD,H_(2)-TPR and TEM analysis proved that smaller CuO particles were formed and the dispersion of Cu on the surface of 13X zeolite was improved via the induction of ammonia.Evaluation on H_(2)S adsorption performance of the adsorbent was carried out using simulated BFG,and the results showed that NH_(3)–CuO/13X-3 has better breakthrough sulfur capacity,which was more than twice the sulfur capacity of CuO/13X.It is proposed that the enhanced desulfurization performance of NH_(3)–CuO/13X is attributed to an abundant pore of 13X,and combined action of 13X and CuO.This work provided an effective way to improve the sulfur capacity of zeolite-based adsorbents via impregnation method by ammonia induction.展开更多
Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction ac...Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction activity of Ti-BFS.A comprehensive utilization route of Ti,Mg and Al from Ti-BFS was proposed.Ti-BFS was firstly roasted with H_(2)SO_(4)to realizes the conversion of Ti,Mg and Al to their corresponding sulphates.The sulphates were leached by dilute H_(2)SO_(4)solution to extraction Ti,Mg and Al from roasted Ti-BFS.The roasting conditions were optimized as follows,sulfuric acid concentration of 85%(mass),temperature of 200℃,acid-slag ratio of 5.5,particle size of Ti-BFS<75μm,and reaction time of 1 h.The extraction rates of titanium,aluminum,and magnesium reached 82.42%,88.78%and 90.53%,respectively.The leachate was hydrolyzed at 102℃for 5 h with a titanium hydrolysis ratio of 96%.After filtration and calcination,TiO_(2)with a purity of 97%(mass)was obtained.Al in the leachate was converted to NH_(4)Al(SO_(4))_(2)·12H_(2)O by the neutralization of ammonia water at pH=4.5.Al_(2)O_(3) was obtained by the calcination of NH_(4)Al(SO_(4))_(2)·12H_(2)O.The residual solution can be used to prepare products of magnesium sulfate.In the proposed process,Ti,Mg and Al were extracted from Ti-BFS and utilized comprehensively to prepare valuable products.The leaching behavior of roasted Ti-BFS with water was also studied.It followed the unreacted shrinking core model.The apparent activation energy was 26.07 kJ·mol^(-1).This research not only provides a viable method for recovering valuable metals in Ti-BFS,but also provides a strategy to comprehensive utilize the valuable elements in Ti-BFS.展开更多
The lining materials for blast furnaces have evolved from brick masonry to monolithic refractory materials.Monolithic castables are widely used in various industrial furnaces.The rapid development of silica sol materi...The lining materials for blast furnaces have evolved from brick masonry to monolithic refractory materials.Monolithic castables are widely used in various industrial furnaces.The rapid development of silica sol materials,combined with the commonly used construction methods of casting and spraying,offers greater flexibility,efficiency,environmental friendliness,and a longer lifespan.Typical monolithic refractory technologies,such as the integral casting technique for the furnace hearth,the pre-applied slag coating technique for the furnace belly and waist,and the inner lining gunning technique,are grounded in scientific theory and practice,thereby advancing the development of refractory materials and enhancing the operational quality of blast furnaces.展开更多
Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,d...Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,deteriorating the gas and liquid permeability of the burden column.This exacerbates coke degradation,significantly impacting the smelting process and increasing the demand for high-quality coke.To investigate the existence state of coke in the hearth,a 2500 m3 BF in China was taken as the research object,and three sets of samples at different heights of the hearth were obtained during planned outage.The results indicate that coke undergoes a significant degradation upon reaching the hearth.The proportion of coke particles smaller than 50 mm ranges from 81.22%to 89.50%.The proportion of coke particles larger than 20 mm decreases as the distance from the centerline of the tuyere increases,while the proportion of particles smaller than 10 mm increases with this distance.Additionally,the closer the bottom of the furnace is,the smaller the coke particle size becomes.The composition of slag filling the coke pores is similar to that of the final slag in the blast furnace,and the graphitization of coke is comparable to that of the final slag.The graphitization of coke starts from the surface of coke and leads to the formation of coke fines,and the graphitization degree of−74μm coke fines is the highest.The temperature has an effect on the reaction rate of coke solution loss,and the higher the temperature is,the faster the reaction rate is.展开更多
The dripping zone in a blast furnace plays a crucial role in connecting the cohesive zone with the hearth,and its stability significantly impacts low-carbon smelting processes.Based on a detailed anatomical study of a...The dripping zone in a blast furnace plays a crucial role in connecting the cohesive zone with the hearth,and its stability significantly impacts low-carbon smelting processes.Based on a detailed anatomical study of a 2200-m3 blast furnace in China,it involves core sampling of the furnace dripping zone and uses scanning electron microscopy to investigate the micro-morphology of potassium(K)and sulfur(S)within this region.The formation process of kalsilite(KAlSiO4)and CaS inside the furnace is elucidated.The results show that when potassium vapor rises to the upper area of the dripping zone,some of it adsorbs onto the coke pore walls and reacts with the dripping slag and coke ash to form kalsilite.The formation pathways of CaS differ between upper and lower areas of the dripping zone.It forms mainly from the reaction of slag with SO2 in the gas flow and from the slag–coke interface reaction.The CaS generated from the slag–coke interface reaction is the major source of CaS in the dripping zone.Based on the formation mechanisms of kalsilite and CaS in the dripping zone,it is possible to regulate their formation by adjusting the temperature,slag phase composition,and the content of harmful elements in the raw materials.It provides theoretical insights into the behavior of harmful elements in the blast furnace,offering guidance for steel enterprises to ensure the stable operation of the dripping zone,reduce fuel consumption,and achieve greener production.展开更多
Ladle furnaces are known for their high power consumption,making research on power-saving process crucial.In response to the defect of thin slag thickness in the industrial production of a 120-t ladle furnace at a ste...Ladle furnaces are known for their high power consumption,making research on power-saving process crucial.In response to the defect of thin slag thickness in the industrial production of a 120-t ladle furnace at a steel plant,with its production of ship plate steel DH36 as the focus,experiments involving adding the foaming agent and shifting power delivery gears were conducted.Based on the principle of measuring alternating current by Rogowski coils,the power consumption during the ladle furnace refining process was calculated theoretically,and the actual industrial power consumption matched with it basically,confirming the accuracy of the theoretical calculations.Additionally,the impacts of argon flow rate,foaming agents,and shifting power delivery gears on power consumption were studied.The results showed that adding 0.59 and 0.50 kg/t foaming agents in two batches improved the refining process of the ladle furnace,allowing for effective submerged-arc operations and saving electric energy of 7.2382 kWh per ton of steel.Similarly,utilizing a power supply mode of 7-step short arc during the refining process significantly enhanced the desulfurization rate of molten steel and saved electric energy of 11.6387 kWh per ton of steel.展开更多
About 70%of the flue gas in the iron-steel industry has achieved multi-pollutant ultra-low emissions in China until 2023,and then the blast furnace gas purification has become the control step and bottleneck.Our resea...About 70%of the flue gas in the iron-steel industry has achieved multi-pollutant ultra-low emissions in China until 2023,and then the blast furnace gas purification has become the control step and bottleneck.Our research group has designed and constructed the world’s first blast furnace gas desulfurization pilot plant with the scale of 2000 Nm^(3)/h in October 2021.The pilot plant is a two-step combined desulfurization device including catalytic hydrolysis of carbonyl sulfur(COS)and absorption-oxidation of H_(2)S,continuously running for 120 days.In the hydrolysis system,one reason for catalyst deactivation has been verified from the sulfur deposition.HCN in blast furnace gas can be hydrolyzed on the hydrolysis catalyst to produce the nitrogen deposition,which is one of the reasons for catalyst deactivation and has never been found in previous studies.The deposition forms of S and N elements are determined,S element forms elemental sulfur and sulfate,while N element forms-NH_(2)and NH_(4)^(+).In the absorption-oxidation system,the O_(2)loading and the residence time have been optimized to control the oxidation of HS^(−)to produce elemental sulfur instead of by-product S_(2)O_(3)^(2−).The balance and distribution of S and N elements have been calculated for thewholemulti-phase system,approximately 84.4%of the sulfur is converted to solid sulfur product,about 1.3%of the sulfur and 19.2%of N element are deposited on the hydrolysis catalyst.The pilot plant provides technical support formulti-pollutant control of blast furnace.展开更多
Resource utilization of metallurgical solid waste is vital for the sustainable development of the steel industry in the context of“dual carbon.”The calcification-carbothermal reduction method was employed to extract...Resource utilization of metallurgical solid waste is vital for the sustainable development of the steel industry in the context of“dual carbon.”The calcification-carbothermal reduction method was employed to extract zinc and iron from electric furnace dust effectively.In this process,calcium oxide reacts with zinc ferrite to form dicalcium ferrite and zinc oxide,which further promotes the effective separation of zinc and iron.However,the addition of pure calcium oxide increases production costs for steel companies.Herein,a new process for dust removal and zinc recovery in electric furnaces has been developed,using electric furnace slag as a calcium agent and mineral trough ash as a reducing agent.Large amounts of dicalcium ferrate phases were detected in the carbothermal reduction products by steel slag synergistic calcification.The reaction mechanism was determined as ZnFe_(2)O_(4)+CaO→Ca_(2)Fe_(2)O_(5)+ZnO→Ca_(2)Fe_(2)O_(5)+Zn(g).Such a two-step reaction path indicated that steel slag can effectively promote the reduction and volatilization of zinc.The experimental optimal roasting parameters were determined as roasting temperature of 1150℃,roasting time of 45 min,calcium to zinc molar ratio of 1.1,and carbon to oxygen molar ratio of 0.8.The mass percentage of added steel slag was recorded as 21.83%,while that of mineral trough ash was 21.85%.Under these conditions,the zinc removal rate above 99%and the metallization rate of pellets of about 75.31%were achieved.Overall,the proposed method looks promising for future efficient separation of zinc and iron in industrial steel slag.展开更多
Currently,chemical furnaces play an important role in the chemical industry.It is necessary to ensure their quality and operation performance,so as to guarantee the efficiency of chemical production.Compared with othe...Currently,chemical furnaces play an important role in the chemical industry.It is necessary to ensure their quality and operation performance,so as to guarantee the efficiency of chemical production.Compared with other furnaces,chemical furnaces have strong particularity,which puts forward higher requirements for the thermal shock resistance of the refractories of furnace linings.This paper studied the thermal shock resistance of the refractories for chemical furnace linings,and proposed measures for improvement,providing experience and technical support for the safe production of chemical enterprises.展开更多
To study the combustion behavior of municipal solid waste(MSW)in blast furnace,the combustion process within the raceway was simulated using computational fluid dynamics.Based on the parameters of an actual blast furn...To study the combustion behavior of municipal solid waste(MSW)in blast furnace,the combustion process within the raceway was simulated using computational fluid dynamics.Based on the parameters of an actual blast furnace,a three-dimensional model including coal lance,blowpipe,tuyere,and raceway was established.The model was then used to compare the combustion characteristics of pulverized coal and MSW in the raceway and to investigate the effects of blast temperature and particle size on the combustion characteristics of MSW in the raceway.The results showed that MSW combusted more rapidly,achieving a maximum temperature of 3839 K in the raceway,comparing to 2974 K during pulverized coal injection.However,the average temperature during MSW injection was 1790 K,which was 73 K lower than that of pulverized coal injection.The maximum velocity during MSW injection was 120 m/s,lower than 188 m/s obtained during pulverized coal injection.MSW could be completely burned out in the middle of the raceway,while the burnout of pulverized coal at this position was only 50%.The combustion effect of MSW makes no difference when the blast temperature increased from 1273 to 1673 K,due to its excellent combustion characteristic.When the MSW particle size was increased from 0.074 to 2 mm,the burnout was 75%,which was still higher than that of pulverized coal injection with a particle size of 0.074 mm.However,injecting larger-sized fuel might increase the risk of tuyere wear.To ensure stable furnace conditions and great combustion,a blast temperature of 1473 K and a MSW particle size of about 1 mm will be better.展开更多
The hydrogen-enriched direct reduction shaft furnace addresses the high CO_(2) emissions associated with the blast furnace process.A discrete element method(DEM)model was introduced to explore how the structure of the...The hydrogen-enriched direct reduction shaft furnace addresses the high CO_(2) emissions associated with the blast furnace process.A discrete element method(DEM)model was introduced to explore how the structure of the diversion cone affects particle descent behavior in a hydrogen-enriched shaft furnace.The results indicated that in the absence of a diversion cone,the descending velocity near the furnace wall zone is significantly lower than that at its center,resulting in a‘V’-shaped burden flow pattern.The discharge velocity has a minor impact on the flow pattern in the shaft furnace.Upon installation of a diversion cone,burden descending velocity becomes more uniform,leading to a‘-’-shaped burden flow pattern.As the bottom of the diversion cone ascends(i.e.,the lower end of the diversion cone is progressively closer to the top),there is an increase in the volume fraction of the dead zone within the shaft furnace.This is particularly evident in the formation of a triangular dead zone at the base of the diversion cone.It is suggested that the lower cone of the bi-conical diversion cone should maintain a sufficient height.展开更多
The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were ...The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were used to investigate the effects of temperature(700–1100℃),CO_(2)(3%–10%),and H_(2)O(1%–9%)concentrations on CH_(4) conversion efficiency.Results indicate that CH_(4) conversion exceeds 90%at temperatures above 1000℃,with CO_(2) and H_(2)O concentrations at 9%and 5%,respectively.During the reforming process,introducing CO_(2) provides additional oxygen,facilitating the oxidation of CH_(4),while H_(2)O enhances H_(2) production through the steam reforming pathway.Experimental findings reveal a CH_(4) conversion of 85.83%with a H_(2)/CO ratio of 5.44 at 1050℃.In addition,an optimal H_(2)O concentration of 6%yields the highest CH_(4) conversion of 84.24%,while CO_(2) exhibits minimal effects on promoting the reforming process.Increasing the metallization rate of pellets from 43%to 92%significantly enhances CH_(4) reforming.This is mainly due to the fact that metallized iron is vital in promoting CH_(4) dissociation and improving syngas yield by providing active sites for the redox cycle of CO_(2) and H_(2)O.展开更多
The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.T...The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.The zinc was selectively extracted from EAFD using CaO roasting followed by NH_(4)Cl solution leaching.The ferric ion was leached from iron scale using HCl solution as acid lixiviant.The experimental results demonstrate a high level of efficiency in the extraction of zinc,with a rate of 97.5%,and the leaching rate of ferric ion is 96.89%.The composition of the leaching solution is primary zinc and iron with low calcium,which is beneficial to the preparation of spinel ferrite.The influence of Ni content(x)and calcination temperature on the synthesis and magnetic properties of NixZn_(1-x)Fe_(2)O_(4)compounds was investigated by X-ray diffraction,scanning electron microscopy,and vibrating sample magnetometry.The results revealed that both Ni content and calcination temperature significantly affect the synthesis and magnetic properties of spinel NixZn_(1-x)Fe_(2)O_(4).Under the conditions of Ni content set at x=0.6,calcination temperature of 1100℃,and a duration of 2 h,a spinel NixZn_(1-x)Fe_(2)O_(4)with high saturation magnetization(Ms=65.7 A m2 kg-1)and low coercivity(Hc=0.056 A m^(-1))was obtained.展开更多
Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blas...Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blast furnace slag(GGBS),a byproduct of industrial production,is used as a mineral admixture to reduce concrete costs and provide excellent performance.This study aimed to investigate the impact of GGBS on the hydration properties of FCSA cement in seawater.Tests were conducted on heat of hydration,compressive strength,mass change,and pH value of pore solution of FCSA cement paste with a water-to-binder ratio of 0.45.X-ray diffraction(XRD)analysis and thermogravimetric analysis were used to determine the hydration products,while mercury intrusion porosimetry(MIP)was used to measure pore structure.The results indicated that the FCSA cement hydration showed a concentrated heat release at early age.The compressive strength of specimens consistently increased over time,where seawater curing enhanced the compressive strength of control samples.The pH value of pore solution decreased to 10.7−10.9 at 90 d when cured in seawater.The primary hydration products of FCSA cement included ettringite,iron hydroxide gel(FH_(3)),and aluminum hydroxide gel(AH_(3)).Moreover,when cured in seawater,Friedel’s salt was formed,which enhanced the compressive strength of the specimen and increased its coefficient of corrosion.Seawater curing gradually increased sample mass,and GGBS refined pore structure while reducing harmful pore proportions.These results suggest that while GGBS can refine pore structure and improve certain aspects of performance,its inclusion may also reduce compressive strength,highlighting the need for a balanced approach in its use for marine applications.展开更多
The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weld...The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weldability of components with thin walls after small punch sampling,such as ethylene cracking furnace tubes,requires further investigation.Therefore,the weldability of in-service ethylene cracking furnace tubes following small punch sampling was investigated through nondestructive testing,microstructural characterization,and mechanical testing.Additionally,the impact of small punch sampling size and residual stress on the creep performance of the specimens was studied using an improved ductility exhaustion model.The results indicate that both the surface and interior of the weld repair areas on new furnace tubes and service-exposed furnace tubes after small-punch sampling are defect-free,exhibiting good weld quality.The strength of the specimens after weld repair was higher than that before sampling,whereas toughness decreased.Weld repair following small punch sampling of furnace tubes is both feasible and necessary.Furthermore,a linear relationship was observed between specimen thickness,diameter,and creep fracture time.The residual stress of welding affects the creep performance of the specimen under different stresses.展开更多
The comprehensive status of blast furnaces was one of the most important factors affecting their economy,quality,and longev-ity.The blast furnace comprehensive status had the nature of“black box,”and it was“unpredi...The comprehensive status of blast furnaces was one of the most important factors affecting their economy,quality,and longev-ity.The blast furnace comprehensive status had the nature of“black box,”and it was“unpredictable.”In this study,a blast furnace com-prehensive status score and prediction method based on a cascade system and a combined model were proposed to address this issue.A dual cascade evaluation system was developed by integrating subjective and objective weighting methods.The analytic hierarchy process,coefficient of variation,entropy weight method,and impart combinatorial games were jointly employed to determine the optimal weight distribution across indicators.Categorized statuses(raw material,gas flow,furnace body,furnace cylinder,and iron-slag)were evaluated.Based on the five categories of the status data,the second cascade was applied to upgrade the quantitative evaluation of the comprehens-ive status.The weights of the different categories were 0.22,0.15,0.22,0.21,and 0.20,respectively.According to the data analysis,the results of the comprehensive status score closely matched the on-site production logs.Based on the blast furnace smelting period,the maximal information coefficient method was applied to the 100 parameters that were most relevant to the comprehensive status.A com-bined prediction model for a comprehensive status score was designed using bidirectional long short-term memory(BiLSTM)and categorical boosting(CatBoost).The test results indicated that the combined model reduced the mean absolute error by an average of 0.275 and increased the hit rate by an average of 5.65 percentage points compared to BiLSTM or CatBoost alone.When the er-ror range was±2.5,the combined model predicted a hit rate of 91.66%for the next hour’s comprehensive status score,and its high accur-acy was deemed satisfactory for the field.SHapley Additive exPlanations(SHAP)and regression fitting were applied to analyze the lin-ear quantitative relationship between the key variables and the comprehensive status score.When the furnace bottom center temperature was increased by 10℃,the comprehensive status score increased by 0.44.This method contributes to a more precise management and control of the comprehensive status of the blast furnace on-site.展开更多
基金financial support provided by the Natural Science Foundation of Hebei Province,China(No.E2024105036)the Tangshan Talent Funding Project,China(Nos.B202302007 and A2021110015)+1 种基金the National Natural Science Foundation of China(No.52264042)the Australian Research Council(No.IH230100010)。
文摘Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.
基金financial support from the National Natural Science Foundation of China(No.52174328)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0062).
文摘The iron and steel industry,standing as a quintessential manufacture example with high consumption,pollution and emissions,faces significant environmental and sustainable development challenges.Electric arc furnace(EAF)steelmaking process mainly uses scrap as raw material and is characterized by environmentally friendly and recyclable process.However,the further development of EAF route in China is limited by the reserve,supply,availability and quality of scrap resource.Direct reduced iron(DRI)is one of typical low-carbon and clean charges,which can effectively make up for the adverse effects caused by the lack of scrap.The physical and chemical properties,classifications,and production technologies of DRI are firstly reviewed.In particular,the reducing gas types,reduction temperature,and reduction mechanism of the DRI production with gas-based shaft furnace(SF)technology are detailed.Considering the crucial role played by DRI application in EAF,the influences of DRI addition on EAF smelting rules and operations including the blending and charging process,heat transfer and melting in molten bath,slag formation operation,refractory corrosion,and slag system evolution are then further discussed.Finally,the comparative analysis and assessment of the consumption level of material and energy as well as the cleaner production both covering the clean chemical composition of molten steel and the clean environment impact in EAF steelmaking with DRI charged are conducted.From perspectives of metallurgical process engineering,a suitable route of hydrogen generation and application(from coke oven gas,methanol,and clean energy power),CO_(2) capture and utilization integrated with SF–EAF process is proposed.In view of the difficulties in large-scale DRI application in EAF,the follow-up work should focus on the investigation of DRI charging and melting,slag system evolution and molten pool reaction rules,as well as the developments of the DRI standardized use technology and intelligent batching and control models.
基金financially supported by the National Natural Science Foundation of China(No.51904026)the Fundamental Research Funds for the Central Universities(No.06500108)。
文摘Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.
基金financially supported by the National Natural Science Foundation of China(Grant No.52078142).
文摘Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.
基金financially supported by National Natural Science Foundation of China(Grant.22076189)National Key Research and Development Program of China(No.2023YFC3707003)the Joint Fund of Yulin University and Dalian National Laboratory for Clean Energy(Grant.YLU-DNL Fund 2022003).
文摘Blast furnace gas(BFG)is an important by-product energy for the iron and steel industry and has been widely used for heating or electricity generation.However,the undesirable contaminants in BFG(especially H_(2)S)generate harmful environmental emissions.The desulfurization of BFG is urgent for integrated steel plants due to the stringent ultra-low emission standards.Compared with other desulfurization materials,zeolite-based adsorbents represent a viable option with low costs and long service life.In this study,an ammonia-induced CuO modified 13X adsorbent(NH_(3)–CuO/13X)was prepared for H_(2)S removal from simulated BFG at low temperature.The XRD,H_(2)-TPR and TEM analysis proved that smaller CuO particles were formed and the dispersion of Cu on the surface of 13X zeolite was improved via the induction of ammonia.Evaluation on H_(2)S adsorption performance of the adsorbent was carried out using simulated BFG,and the results showed that NH_(3)–CuO/13X-3 has better breakthrough sulfur capacity,which was more than twice the sulfur capacity of CuO/13X.It is proposed that the enhanced desulfurization performance of NH_(3)–CuO/13X is attributed to an abundant pore of 13X,and combined action of 13X and CuO.This work provided an effective way to improve the sulfur capacity of zeolite-based adsorbents via impregnation method by ammonia induction.
基金the Pangang Group Company Limited for its financial supportthe support from the Fundamental Research Funds for the Central Universities(SCU2024D009)。
文摘Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction activity of Ti-BFS.A comprehensive utilization route of Ti,Mg and Al from Ti-BFS was proposed.Ti-BFS was firstly roasted with H_(2)SO_(4)to realizes the conversion of Ti,Mg and Al to their corresponding sulphates.The sulphates were leached by dilute H_(2)SO_(4)solution to extraction Ti,Mg and Al from roasted Ti-BFS.The roasting conditions were optimized as follows,sulfuric acid concentration of 85%(mass),temperature of 200℃,acid-slag ratio of 5.5,particle size of Ti-BFS<75μm,and reaction time of 1 h.The extraction rates of titanium,aluminum,and magnesium reached 82.42%,88.78%and 90.53%,respectively.The leachate was hydrolyzed at 102℃for 5 h with a titanium hydrolysis ratio of 96%.After filtration and calcination,TiO_(2)with a purity of 97%(mass)was obtained.Al in the leachate was converted to NH_(4)Al(SO_(4))_(2)·12H_(2)O by the neutralization of ammonia water at pH=4.5.Al_(2)O_(3) was obtained by the calcination of NH_(4)Al(SO_(4))_(2)·12H_(2)O.The residual solution can be used to prepare products of magnesium sulfate.In the proposed process,Ti,Mg and Al were extracted from Ti-BFS and utilized comprehensively to prepare valuable products.The leaching behavior of roasted Ti-BFS with water was also studied.It followed the unreacted shrinking core model.The apparent activation energy was 26.07 kJ·mol^(-1).This research not only provides a viable method for recovering valuable metals in Ti-BFS,but also provides a strategy to comprehensive utilize the valuable elements in Ti-BFS.
文摘The lining materials for blast furnaces have evolved from brick masonry to monolithic refractory materials.Monolithic castables are widely used in various industrial furnaces.The rapid development of silica sol materials,combined with the commonly used construction methods of casting and spraying,offers greater flexibility,efficiency,environmental friendliness,and a longer lifespan.Typical monolithic refractory technologies,such as the integral casting technique for the furnace hearth,the pre-applied slag coating technique for the furnace belly and waist,and the inner lining gunning technique,are grounded in scientific theory and practice,thereby advancing the development of refractory materials and enhancing the operational quality of blast furnaces.
基金supported by the National Natural Science Foundation of China(Grant No.U1960205)China Baowu Low Carbon Metallurgy Innovation Foundation(Grant Nos.BWLCF202101 and BWLCF202104)China Minmetals Science and Technology Special Plan Foundation(Grant No.2020ZXA01).
文摘Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,deteriorating the gas and liquid permeability of the burden column.This exacerbates coke degradation,significantly impacting the smelting process and increasing the demand for high-quality coke.To investigate the existence state of coke in the hearth,a 2500 m3 BF in China was taken as the research object,and three sets of samples at different heights of the hearth were obtained during planned outage.The results indicate that coke undergoes a significant degradation upon reaching the hearth.The proportion of coke particles smaller than 50 mm ranges from 81.22%to 89.50%.The proportion of coke particles larger than 20 mm decreases as the distance from the centerline of the tuyere increases,while the proportion of particles smaller than 10 mm increases with this distance.Additionally,the closer the bottom of the furnace is,the smaller the coke particle size becomes.The composition of slag filling the coke pores is similar to that of the final slag in the blast furnace,and the graphitization of coke is comparable to that of the final slag.The graphitization of coke starts from the surface of coke and leads to the formation of coke fines,and the graphitization degree of−74μm coke fines is the highest.The temperature has an effect on the reaction rate of coke solution loss,and the higher the temperature is,the faster the reaction rate is.
基金financially supported by Key Laboratory of Metallurgical Industry Safety and Risk Prevention and Control,Ministry of Emergency Management,and the Fundamental Research Funds for the Central Universities(No.FRF-IDRY-22-021]).
文摘The dripping zone in a blast furnace plays a crucial role in connecting the cohesive zone with the hearth,and its stability significantly impacts low-carbon smelting processes.Based on a detailed anatomical study of a 2200-m3 blast furnace in China,it involves core sampling of the furnace dripping zone and uses scanning electron microscopy to investigate the micro-morphology of potassium(K)and sulfur(S)within this region.The formation process of kalsilite(KAlSiO4)and CaS inside the furnace is elucidated.The results show that when potassium vapor rises to the upper area of the dripping zone,some of it adsorbs onto the coke pore walls and reacts with the dripping slag and coke ash to form kalsilite.The formation pathways of CaS differ between upper and lower areas of the dripping zone.It forms mainly from the reaction of slag with SO2 in the gas flow and from the slag–coke interface reaction.The CaS generated from the slag–coke interface reaction is the major source of CaS in the dripping zone.Based on the formation mechanisms of kalsilite and CaS in the dripping zone,it is possible to regulate their formation by adjusting the temperature,slag phase composition,and the content of harmful elements in the raw materials.It provides theoretical insights into the behavior of harmful elements in the blast furnace,offering guidance for steel enterprises to ensure the stable operation of the dripping zone,reduce fuel consumption,and achieve greener production.
基金The authors gratefully express their appreciation to the National Natural Science Foundation of China(51834002)for sponsoring this work.
文摘Ladle furnaces are known for their high power consumption,making research on power-saving process crucial.In response to the defect of thin slag thickness in the industrial production of a 120-t ladle furnace at a steel plant,with its production of ship plate steel DH36 as the focus,experiments involving adding the foaming agent and shifting power delivery gears were conducted.Based on the principle of measuring alternating current by Rogowski coils,the power consumption during the ladle furnace refining process was calculated theoretically,and the actual industrial power consumption matched with it basically,confirming the accuracy of the theoretical calculations.Additionally,the impacts of argon flow rate,foaming agents,and shifting power delivery gears on power consumption were studied.The results showed that adding 0.59 and 0.50 kg/t foaming agents in two batches improved the refining process of the ladle furnace,allowing for effective submerged-arc operations and saving electric energy of 7.2382 kWh per ton of steel.Similarly,utilizing a power supply mode of 7-step short arc during the refining process significantly enhanced the desulfurization rate of molten steel and saved electric energy of 11.6387 kWh per ton of steel.
基金supported by the Key Research and Development Program of Hebei Province(No.21373702D)the Key Science and Technology Program of HBIS Group Co.,Ltd.(No.HG2021117)+1 种基金the National Natural Science Foundation of China(No.52370124)the National Key R&D Program of China(No.2023YFC3707003).
文摘About 70%of the flue gas in the iron-steel industry has achieved multi-pollutant ultra-low emissions in China until 2023,and then the blast furnace gas purification has become the control step and bottleneck.Our research group has designed and constructed the world’s first blast furnace gas desulfurization pilot plant with the scale of 2000 Nm^(3)/h in October 2021.The pilot plant is a two-step combined desulfurization device including catalytic hydrolysis of carbonyl sulfur(COS)and absorption-oxidation of H_(2)S,continuously running for 120 days.In the hydrolysis system,one reason for catalyst deactivation has been verified from the sulfur deposition.HCN in blast furnace gas can be hydrolyzed on the hydrolysis catalyst to produce the nitrogen deposition,which is one of the reasons for catalyst deactivation and has never been found in previous studies.The deposition forms of S and N elements are determined,S element forms elemental sulfur and sulfate,while N element forms-NH_(2)and NH_(4)^(+).In the absorption-oxidation system,the O_(2)loading and the residence time have been optimized to control the oxidation of HS^(−)to produce elemental sulfur instead of by-product S_(2)O_(3)^(2−).The balance and distribution of S and N elements have been calculated for thewholemulti-phase system,approximately 84.4%of the sulfur is converted to solid sulfur product,about 1.3%of the sulfur and 19.2%of N element are deposited on the hydrolysis catalyst.The pilot plant provides technical support formulti-pollutant control of blast furnace.
基金the support from Graduate Student Scientific Research Innovation Projects in Jiangsu Province(KYCX22_3804)Natural Science Foundation of Jiangsu Province(No.BK20210888).
文摘Resource utilization of metallurgical solid waste is vital for the sustainable development of the steel industry in the context of“dual carbon.”The calcification-carbothermal reduction method was employed to extract zinc and iron from electric furnace dust effectively.In this process,calcium oxide reacts with zinc ferrite to form dicalcium ferrite and zinc oxide,which further promotes the effective separation of zinc and iron.However,the addition of pure calcium oxide increases production costs for steel companies.Herein,a new process for dust removal and zinc recovery in electric furnaces has been developed,using electric furnace slag as a calcium agent and mineral trough ash as a reducing agent.Large amounts of dicalcium ferrate phases were detected in the carbothermal reduction products by steel slag synergistic calcification.The reaction mechanism was determined as ZnFe_(2)O_(4)+CaO→Ca_(2)Fe_(2)O_(5)+ZnO→Ca_(2)Fe_(2)O_(5)+Zn(g).Such a two-step reaction path indicated that steel slag can effectively promote the reduction and volatilization of zinc.The experimental optimal roasting parameters were determined as roasting temperature of 1150℃,roasting time of 45 min,calcium to zinc molar ratio of 1.1,and carbon to oxygen molar ratio of 0.8.The mass percentage of added steel slag was recorded as 21.83%,while that of mineral trough ash was 21.85%.Under these conditions,the zinc removal rate above 99%and the metallization rate of pellets of about 75.31%were achieved.Overall,the proposed method looks promising for future efficient separation of zinc and iron in industrial steel slag.
文摘Currently,chemical furnaces play an important role in the chemical industry.It is necessary to ensure their quality and operation performance,so as to guarantee the efficiency of chemical production.Compared with other furnaces,chemical furnaces have strong particularity,which puts forward higher requirements for the thermal shock resistance of the refractories of furnace linings.This paper studied the thermal shock resistance of the refractories for chemical furnace linings,and proposed measures for improvement,providing experience and technical support for the safe production of chemical enterprises.
基金supported by the National Natural Science Foundation of China(Nos.51804024 and 52474342)the Fundamental Research Funds for the Central Universities(No.FRF-IC-20-09)the State Key Laboratory of Advanced Metallurgy of University of Science and Technology Beijing(No.41621002).
文摘To study the combustion behavior of municipal solid waste(MSW)in blast furnace,the combustion process within the raceway was simulated using computational fluid dynamics.Based on the parameters of an actual blast furnace,a three-dimensional model including coal lance,blowpipe,tuyere,and raceway was established.The model was then used to compare the combustion characteristics of pulverized coal and MSW in the raceway and to investigate the effects of blast temperature and particle size on the combustion characteristics of MSW in the raceway.The results showed that MSW combusted more rapidly,achieving a maximum temperature of 3839 K in the raceway,comparing to 2974 K during pulverized coal injection.However,the average temperature during MSW injection was 1790 K,which was 73 K lower than that of pulverized coal injection.The maximum velocity during MSW injection was 120 m/s,lower than 188 m/s obtained during pulverized coal injection.MSW could be completely burned out in the middle of the raceway,while the burnout of pulverized coal at this position was only 50%.The combustion effect of MSW makes no difference when the blast temperature increased from 1273 to 1673 K,due to its excellent combustion characteristic.When the MSW particle size was increased from 0.074 to 2 mm,the burnout was 75%,which was still higher than that of pulverized coal injection with a particle size of 0.074 mm.However,injecting larger-sized fuel might increase the risk of tuyere wear.To ensure stable furnace conditions and great combustion,a blast temperature of 1473 K and a MSW particle size of about 1 mm will be better.
基金the National Key R&D Program of China(Nos.2021YFC2902400 and 2021YFC2902401)the project of State Key Laboratory of Intelligent Optimized Manufacturing in Mining&Metallurgy Process(No.BGRIMM-KZSKL-2023-14).
文摘The hydrogen-enriched direct reduction shaft furnace addresses the high CO_(2) emissions associated with the blast furnace process.A discrete element method(DEM)model was introduced to explore how the structure of the diversion cone affects particle descent behavior in a hydrogen-enriched shaft furnace.The results indicated that in the absence of a diversion cone,the descending velocity near the furnace wall zone is significantly lower than that at its center,resulting in a‘V’-shaped burden flow pattern.The discharge velocity has a minor impact on the flow pattern in the shaft furnace.Upon installation of a diversion cone,burden descending velocity becomes more uniform,leading to a‘-’-shaped burden flow pattern.As the bottom of the diversion cone ascends(i.e.,the lower end of the diversion cone is progressively closer to the top),there is an increase in the volume fraction of the dead zone within the shaft furnace.This is particularly evident in the formation of a triangular dead zone at the base of the diversion cone.It is suggested that the lower cone of the bi-conical diversion cone should maintain a sufficient height.
基金financially supported by the National Natural Science Foundation of China(No.52004339)the Key Research and Development Project of Hunan Province,China(No.2022SK2075)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(BWLCF202216)Central South University Graduate Student Independent Exploration and Innovation Project(2024ZZTS0378).
文摘The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were used to investigate the effects of temperature(700–1100℃),CO_(2)(3%–10%),and H_(2)O(1%–9%)concentrations on CH_(4) conversion efficiency.Results indicate that CH_(4) conversion exceeds 90%at temperatures above 1000℃,with CO_(2) and H_(2)O concentrations at 9%and 5%,respectively.During the reforming process,introducing CO_(2) provides additional oxygen,facilitating the oxidation of CH_(4),while H_(2)O enhances H_(2) production through the steam reforming pathway.Experimental findings reveal a CH_(4) conversion of 85.83%with a H_(2)/CO ratio of 5.44 at 1050℃.In addition,an optimal H_(2)O concentration of 6%yields the highest CH_(4) conversion of 84.24%,while CO_(2) exhibits minimal effects on promoting the reforming process.Increasing the metallization rate of pellets from 43%to 92%significantly enhances CH_(4) reforming.This is mainly due to the fact that metallized iron is vital in promoting CH_(4) dissociation and improving syngas yield by providing active sites for the redox cycle of CO_(2) and H_(2)O.
基金supported by the National Natural Science Foundation of China(No.52374344).
文摘The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.The zinc was selectively extracted from EAFD using CaO roasting followed by NH_(4)Cl solution leaching.The ferric ion was leached from iron scale using HCl solution as acid lixiviant.The experimental results demonstrate a high level of efficiency in the extraction of zinc,with a rate of 97.5%,and the leaching rate of ferric ion is 96.89%.The composition of the leaching solution is primary zinc and iron with low calcium,which is beneficial to the preparation of spinel ferrite.The influence of Ni content(x)and calcination temperature on the synthesis and magnetic properties of NixZn_(1-x)Fe_(2)O_(4)compounds was investigated by X-ray diffraction,scanning electron microscopy,and vibrating sample magnetometry.The results revealed that both Ni content and calcination temperature significantly affect the synthesis and magnetic properties of spinel NixZn_(1-x)Fe_(2)O_(4).Under the conditions of Ni content set at x=0.6,calcination temperature of 1100℃,and a duration of 2 h,a spinel NixZn_(1-x)Fe_(2)O_(4)with high saturation magnetization(Ms=65.7 A m2 kg-1)and low coercivity(Hc=0.056 A m^(-1))was obtained.
基金Project(2023DJC182)supported by the Department of Science and Technology of Hubei Province,ChinaProjects(51608402,51602229)supported by the National Natural Science Foundation of ChinaProject(2021-2075-38)supported by the Department of Housing and Urban-Rural Development of Hubei Province,China。
文摘Ferrite-rich calcium sulfoaluminate(FCSA)cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high.Ground granulated blast furnace slag(GGBS),a byproduct of industrial production,is used as a mineral admixture to reduce concrete costs and provide excellent performance.This study aimed to investigate the impact of GGBS on the hydration properties of FCSA cement in seawater.Tests were conducted on heat of hydration,compressive strength,mass change,and pH value of pore solution of FCSA cement paste with a water-to-binder ratio of 0.45.X-ray diffraction(XRD)analysis and thermogravimetric analysis were used to determine the hydration products,while mercury intrusion porosimetry(MIP)was used to measure pore structure.The results indicated that the FCSA cement hydration showed a concentrated heat release at early age.The compressive strength of specimens consistently increased over time,where seawater curing enhanced the compressive strength of control samples.The pH value of pore solution decreased to 10.7−10.9 at 90 d when cured in seawater.The primary hydration products of FCSA cement included ettringite,iron hydroxide gel(FH_(3)),and aluminum hydroxide gel(AH_(3)).Moreover,when cured in seawater,Friedel’s salt was formed,which enhanced the compressive strength of the specimen and increased its coefficient of corrosion.Seawater curing gradually increased sample mass,and GGBS refined pore structure while reducing harmful pore proportions.These results suggest that while GGBS can refine pore structure and improve certain aspects of performance,its inclusion may also reduce compressive strength,highlighting the need for a balanced approach in its use for marine applications.
基金supports provided by the National Natural Science Foundation of China(No.52372330).
文摘The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weldability of components with thin walls after small punch sampling,such as ethylene cracking furnace tubes,requires further investigation.Therefore,the weldability of in-service ethylene cracking furnace tubes following small punch sampling was investigated through nondestructive testing,microstructural characterization,and mechanical testing.Additionally,the impact of small punch sampling size and residual stress on the creep performance of the specimens was studied using an improved ductility exhaustion model.The results indicate that both the surface and interior of the weld repair areas on new furnace tubes and service-exposed furnace tubes after small-punch sampling are defect-free,exhibiting good weld quality.The strength of the specimens after weld repair was higher than that before sampling,whereas toughness decreased.Weld repair following small punch sampling of furnace tubes is both feasible and necessary.Furthermore,a linear relationship was observed between specimen thickness,diameter,and creep fracture time.The residual stress of welding affects the creep performance of the specimen under different stresses.
基金supported by the Youth Program of National Natural Science Foundation of China(No.52404343)the General Program of National Natural Science Foundation of China(No.52274326)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.N2425031)the Seventh Batch of Ten Thousand Talents Plan of China(No.ZX20220553)the Liaoning Province Science and Technology Plan Joint Program,China(Key Research and Development Program Project)(No.2023JH2/101800058).
文摘The comprehensive status of blast furnaces was one of the most important factors affecting their economy,quality,and longev-ity.The blast furnace comprehensive status had the nature of“black box,”and it was“unpredictable.”In this study,a blast furnace com-prehensive status score and prediction method based on a cascade system and a combined model were proposed to address this issue.A dual cascade evaluation system was developed by integrating subjective and objective weighting methods.The analytic hierarchy process,coefficient of variation,entropy weight method,and impart combinatorial games were jointly employed to determine the optimal weight distribution across indicators.Categorized statuses(raw material,gas flow,furnace body,furnace cylinder,and iron-slag)were evaluated.Based on the five categories of the status data,the second cascade was applied to upgrade the quantitative evaluation of the comprehens-ive status.The weights of the different categories were 0.22,0.15,0.22,0.21,and 0.20,respectively.According to the data analysis,the results of the comprehensive status score closely matched the on-site production logs.Based on the blast furnace smelting period,the maximal information coefficient method was applied to the 100 parameters that were most relevant to the comprehensive status.A com-bined prediction model for a comprehensive status score was designed using bidirectional long short-term memory(BiLSTM)and categorical boosting(CatBoost).The test results indicated that the combined model reduced the mean absolute error by an average of 0.275 and increased the hit rate by an average of 5.65 percentage points compared to BiLSTM or CatBoost alone.When the er-ror range was±2.5,the combined model predicted a hit rate of 91.66%for the next hour’s comprehensive status score,and its high accur-acy was deemed satisfactory for the field.SHapley Additive exPlanations(SHAP)and regression fitting were applied to analyze the lin-ear quantitative relationship between the key variables and the comprehensive status score.When the furnace bottom center temperature was increased by 10℃,the comprehensive status score increased by 0.44.This method contributes to a more precise management and control of the comprehensive status of the blast furnace on-site.
