An innovative process of blast furnace(BF) operation involving charging with low-titanium vanadium–titanium magnetite carbon composite hot briquette(LVTM-CCB) was proposed for utilizing LVTM and conserving energy. In...An innovative process of blast furnace(BF) operation involving charging with low-titanium vanadium–titanium magnetite carbon composite hot briquette(LVTM-CCB) was proposed for utilizing LVTM and conserving energy. In this study, the effect of LVTM-CCB charging ratio on the softening, melting, and dripping behaviors of the mixed burden was explored systemically, and the migration of valuable elements V and Cr was extensively investigated. The results show that with increasing LVTM-CCB charging ratio, the softening interval T_(40)- T_4 increases from 146.1°C to 266.1°C, and the melting interval T_D- T_S first decreases from 137.2°C to 129.5°C and then increases from 129.5°C to 133.2°C. Moreover, the cohesive zone becomes narrower and then wider, and its location shifts slightly downward. In addition, the recovery ratios of V and Cr in dripped iron first increase and then decrease, reaching maximum values of 14.552% and 28.163%, respectively, when the charging ratio is 25%. A proper LVTM-CCB charging ratio would improve the softening–melting behavior of the mixed burden; however, Ti(C,N) would be generated rapidly in slag when the charging ratio exceeds 25%, which is not favorable for BF operation. When considering the comprehensive softening–melting behavior of the mixed burden and the recovery ratios of V and Cr, the recommended LVTM-CCB charging ratio is 20%.展开更多
The effect of hydrogen injection on blast furnace operation and carbon dioxide emissions was simulated using a 1D steady-state zonal model.The maximum hydrogen injection rate was evaluated on the basis of the simulati...The effect of hydrogen injection on blast furnace operation and carbon dioxide emissions was simulated using a 1D steady-state zonal model.The maximum hydrogen injection rate was evaluated on the basis of the simulation of the vertical temperature pattern in the blast furnace with a focus on the thermal reserve zone.The effects of blast temperature and oxygen enrichment were also examined to estimate coke replacement ratio,productivity,hydrogen utilization efficiency,and carbon dioxide emission reduction.For blast temperature of 1200℃,the maximum hydrogen injection rate was 19.0 and 28.3 kg of H_(2)/t of hot metal(HM)for oxygen enrichment of 2vol%and 12vol%,respectively.Results showed a coke replacement ratio of 3-4 kg of coke/kg of H_(2),direct CO_(2) emission reduction of 10.2%-17.8%,and increased productivity by up to 13.7%depending on oxygen enrichment level.Increasing blast temperature further reduced the direct CO_(2) emissions.Hydrogen utilization degree reached the maximum of 0.52-0.54 H_(2)O/(H_(2)O+H_(2)).The decarbonization potential of hydrogen injection was estimated in the range from 9.4 t of CO_(2)/t of H_(2) to 9.7 t of CO_(2)/t of H_(2).For economic feasibility,hydrogen injection requires revolutionary progress in terms of low-cost H_(2) generation unless the technological change is motivated by the carbon emission cost.Hydrogen injection may unfavorably affect the radial temperature pattern of the raceway,which could be addressed by adopting appropriate injection techniques.展开更多
The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile con...The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile content of biochar ranged from 16.19%to 45.35%,and the alkali metal content,ash content,and specific surface area were significantly reduced.The optimal route for biochar pro-duction is hydrothermal carbonization-pyrolysis(P-HC),resulting in biochar with a higher calorific value,C=C structure,and increased graphitization degree.The apparent activation energy(E)of the sample ranges from 199.1 to 324.8 kJ/mol,with P-HC having an E of 277.8 kJ/mol,lower than that of raw biomass,primary biochar,and anthracite.This makes P-HC more suitable for blast furnace injection fuel.Additionally,the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits.P-HC of-fers the highest potential for carbon emission reduction,capable of reducing emissions by 96.04 kg/t when replacing 40wt%coal injec-tion.展开更多
To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparat...To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.展开更多
Blast furnace(BF)burden surface contains the most abundant,intuitive and credible smelting information and acquiring high-definition and high-brightness optical images of which is essential to realize precise material...Blast furnace(BF)burden surface contains the most abundant,intuitive and credible smelting information and acquiring high-definition and high-brightness optical images of which is essential to realize precise material charging control,optimize gas flow distribution and improve ironmaking efficiency.It has been challengeable to obtain high-quality optical burden surface images under high-temperature,high-dust,and extremelydim(less than 0.001 Lux)environment.Based on a novel endoscopic sensing detection idea,a reverse telephoto structure starlight imaging system with large field of view and large aperture is designed.Combined with a water-air dual cooling intelligent self-maintenance protection device and the imaging system,a starlight high-temperature industrial endoscope is developed to obtain clear optical burden surface images stably under the harsh environment.Based on an endoscope imaging area model,a material flow trajectory model and a gas-dust coupling distribution model,an optimal installation position and posture configuration method for the endoscope is proposed,which maximizes the effective imaging area and ensures large-area,safe and stable imaging of the device in a confined space.Industrial experiments and applications indicate that the proposed method obtains clear and reliable large-area optical burden surface images and reveals new BF conditions,providing key data support for green iron smelting.展开更多
A blast furnace slag zeolite(BFSZ)material was successfully synthesized from BFS by alkaline fusion and hydrothermal treatment.Via the analyses of XRD,FT-IR,FE-SEM,XRF,CEC and BET surface area measurement,when zeolite...A blast furnace slag zeolite(BFSZ)material was successfully synthesized from BFS by alkaline fusion and hydrothermal treatment.Via the analyses of XRD,FT-IR,FE-SEM,XRF,CEC and BET surface area measurement,when zeolite was synthesized at a crystallization temperature of 100℃with initial Si/Al ratio of 1:1,the main composition in the product is Na-A zeolite.Under the above conditions,the BFSZ was synthesized with CEC of 3.06 meq/g and maximum BET surface area of 37.55 m^(2)·g^(-1).Moreover,the incorporating of BFS-derived minor metals(such as Mg,Fe,and Ca)are found to be of little importance for the synthesis of BFSZ.Thus the obtained BFSZ material has a great adsorption performance for removing Mn^(2+),Cu^(2+),and NH_(4)^(+)ions diluted in water,owing to the higher CEC.展开更多
Due to the problems of few fault samples and large data fluctuations in the blast furnace(BF)ironmaking process,some transfer learning-based fault diagnosis methods are proposed.The vast majority of such methods perfo...Due to the problems of few fault samples and large data fluctuations in the blast furnace(BF)ironmaking process,some transfer learning-based fault diagnosis methods are proposed.The vast majority of such methods perform distribution adaptation by reducing the distance between data distributions and applying a classifier to generate pseudo-labels for self-training.However,since the training data is dominated by labeled source domain data,such classifiers tend to be weak classifiers in the target domain.In addition,the features generated after domain adaptation are likely to be at the decision boundary,resulting in a loss of classification performance.Hence,we propose a novel method called minimax entropy-based co-training(MMEC)that adversarially optimizes a transferable fault diagnosis model for the BF.The structure of MMEC includes a dual-view feature extractor,followed by two classifiers that compute the feature's cosine similarity to representative vector of each class.Knowledge transfer is achieved by alternately increasing and decreasing the entropy of unlabeled target samples with the classifier and the feature extractor,respectively.Transfer BF fault diagnosis experiments show that our method improves accuracy by about 5%over state-of-the-art methods.展开更多
Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due t...Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due to their environmental sustainability and the feasibility of immobilizing industrial waste.In this paper,steel slag(SS)fines were investigated as auxiliary materials of blast furnace slag(BFS)based geopolymer.The hydration heat properties,flowability,compressive strength,sorptivity coefficient,X-ray diffraction(XRD),and scanning electron microscopy(SEM)of the geopolymer pastes were determined.The results showed that the incorporation of SS weakened the reactivity of the BFS-based geopolymer paste and improved the flow values of the paste.The compressive strength of the geopolymer with 20%SS content reached 117 MPa at 28 d.The geopolymer specimens with high compressive strength showed a low sorptivity coefficient.The microscopic results showed that the addition of the appropriate amount of SS reduced the cracks,improved the density of the geopolymer,and produced a geopolymer composite with excellent mechanical properties.展开更多
A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting na...A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of iron-bearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.展开更多
Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal ...Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal shock resistance lead these refractory materials to be used as channel linings of blast furnaces,where they are exposed to the attack by slag,molten steel,working cycles and sudden temperature changes between 25℃(room temperature)and 1520℃(the temperature of molten pig iron).In this work,microstructural changes in post-mortem aluminous refractory bricks were investigated by apparent porosity,X-ray diffraction analysis(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,and X-ray dispersion energy spectrometry(SEM/EDS).The results showed an increase in the apparent porosity and the bulk density and the presence of the phases mullite,sillimanite,alumina,and quartz in the post-mortem brick.Calcium and magnesium were not detected in the microstructure of the post-mortem brick,indicating that slags did not corrode these refractory materials.Therefore,the microstructural changes that occurred in the post-mortem bricks must be due to thermal cycling.In the X-ray diffraction(XRD)test,mullite,sillimanite,quartz,andα-alumina phases were identified.These results indicate that the aluminous refractory was obtained from sillimanite.In infrared spectroscopy(FTIR)it was possible to identify the vibration bands referring to the Si-O and Al-O bonds.The increase in the porosity is a result of cracks caused by work cycles at high temperatures and the temperature gradient to which the refractory was subjected during use.Through the micrograph it was possible to identify the presence of acicular mullite.The absence of magnesium and calcium in the microanalysis results by energy dispersed X-ray spectrometry(EDS)indicates that there was no infiltration by slag or liquid iron.These results indicate that the microstructural changes that occurred in the post-mortem aluminous refractory were of a thermal nature.展开更多
A SiC assembled large block for blast furnace tuyeres was prepared using silicon carbide particles(3-1 and 1-0.088 mm)and fine powder(<0.088 mm),silicon powder(<0.088 mm),industrial carbon black(N990),microsili...A SiC assembled large block for blast furnace tuyeres was prepared using silicon carbide particles(3-1 and 1-0.088 mm)and fine powder(<0.088 mm),silicon powder(<0.088 mm),industrial carbon black(N990),microsilica,ρ-Al_(2)O_(3) powder,etc.as raw materials.The developed block was compared with a silicon nitride bonded silicon carbide brick,a self-bonded silicon carbide brick and an imported self-bonded silicon carbide block to analyze and evaluate their service performance.The results show that:(1)in the 0-100 mm zone,the SiC large block mainly consists ofβ-SiC and nitrides such as O'-SiAlON,β-SiAlON,α-Si_(3)N_(4),and Si_(2)N_(2)O,the bulk density is 2.68-2.70 g·cm^(-3),the apparent porosity is 14%-15%,and the material structure is uniform;(2)in the 0-100 mm zone,β-SiC nano-whiskers intercalate with nitrides;with the depth increasing,the number of flocculentβ-SiC nano-whiskers increases,while the number of nitrides decreases;when the depth reaches 150 mm or more,the main bonding phases areβ-SiC and mullite;(3)compared with the reference products,the developed SiC large block has a good basic performance,and after alkali corrosion,the mass change rate is-0.1%,which is obviously superior to the imported self-bonded silicon carbide and the homemade silicon nitride bonded silicon carbide materials.展开更多
The article introduces the composition and working principle of the batching and weighing system underneath the blast furnace hearth.Besides,the shortcomings of the batching and weighing system during installation,deb...The article introduces the composition and working principle of the batching and weighing system underneath the blast furnace hearth.Besides,the shortcomings of the batching and weighing system during installation,debugging,and calibration,as well as the dynamic errors in the batching process are also analyzed.Corresponding solutions are then provided.展开更多
Blast furnace operation with hot burden charging was numerically simulated to preliminarily analyze its advantages and disadvantages.Multi-fluid blast furnace model was utilized to simulate hot burden charging operati...Blast furnace operation with hot burden charging was numerically simulated to preliminarily analyze its advantages and disadvantages.Multi-fluid blast furnace model was utilized to simulate hot burden charging operations under the conditions that the charging temperatures of pellet and coke were supposed separately or simultaneously as800℃.The results showed that,with hot burden charging,the furnace top temperature significantly increased in comparison to the conventional operation with cold burden charging.However,in-furnace temperature decreased,which decelerated the reduction rate of ferrous burdens.The concentrations of reducing gases were decreased in the furnace.The height of cohesive zone shifted downwards.When the charging temperatures of pellet and coke were simultaneously 800℃(PC800),coke rate,fuel rate and carbon emission rate were decreased by 13.4,22.1and19.25kg·t-1,respectively.The ratio of ore to coke,solid burden charging rate and hot metal productivity were increased by 4.79%,7.55kg·s-1 and 6.38%,respectively.Heat taken away by top gas and energy consumption per ton hot metal were increased by 68.97%and 6.40%,respectively.Generally speaking,hot burden charging was adverse to energy utilization of blast furnace.展开更多
The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimet...The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimetric analysis. The experimental gas compositions and the corresponding temperature were chosen according to data reported for industrial BFs. The gasification behavior of coke was described by the Random Pore Model (RPM), Volumetric Model (VM), and Grain Model (GM). Results showed that the gas composition of the coke gasification zone in BF changes slightly and that the temperature is the most important factor affecting coke gasification. The lower activation energy of coke samples (Coke Reaction Index (CRI)>50) is due to the high Fe2O3 in the ash, lower degree of graphitization, and larger pore structure. In addition, the choice of kinetic model does not differ substantially in describing the gasification mechanism of coke in a BF.展开更多
A variety of techniques, such as chemical analysis, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, were applied to characterize the adhesion protective layer formed below the blast...A variety of techniques, such as chemical analysis, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, were applied to characterize the adhesion protective layer formed below the blast furnace taphole level when a certain amount of titanium-bearing burden was used. Samples of the protective layer were extracted to identify the chemical composition, phase assemblage, andistribution. Furthermore, the formation mechanism of the protective layer was determined after clarifying the source of each componenFinally, a technical strategy was proposed for achieving a stable protective layer in the hearth. The results show that the protective layemainly exists in a bilayer form in the sidewall, namely, a titanium-bearing layer and a graphite layer. Both the layers contain the slag phaswhose major crystalline phase is magnesium melilite(Ca_2Mg Si_2O_7) and the main source of the slag phase is coke ash. It is clearly determinethat solid particles such as graphite, Ti(C,N) and Mg Al_2O_4 play an important role in the formation of the protective layer, and the key factofor promoting the formation of a stable protective layer is reasonable control of the evolution behavior of coke.展开更多
The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 6...The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of-43 μm accounting for 69.02 wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO_2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage(≤4 wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF_2 and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F-when used as reducing agents, leading to weaker effects of fluorite.展开更多
Large quantities of CO_2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO_2 emission reduction and comprehensive utilisation of t...Large quantities of CO_2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO_2 emission reduction and comprehensive utilisation of the solid waste. In this study, a recyclable extractant,(NH_4)_2SO_4, was used to extract calcium and magnesium from blast furnace slag(main phases of gehlenite and akermanite) by using low-temperature roasting to fix CO_2 through aqueous carbonation. The process parameters and efficiency of the roasting extraction, mineralisation, and Al recovery were investigated in detail. The results showed that the extractions of Ca, Mg, and Al can reach almost 100% at an(NH4)_2SO_4-to-slag mass ratio of 3:1 and at 370°C in 1 h. Adjusting the p H value of the leaching solution of the roasted slag to 5.5 with the NH_3 released during the roasting resulted in 99% Al precipitation, while co-precipitation of Mg was lower than 2%. The Mg-rich leachate after the depletion of Al and the leaching residue(main phases of CaSO_4 and SiO_2) were carbonated using(NH_4)_2CO_3 and NH_4HCO_3 solutions, respectively, under mild conditions. Approximately 99% of Ca and 89% of Mg in the blast furnace slag were converted into CaCO_3 and(NH_4)_2 Mg(CO_3)_2·4 H_2O,respectively. The latter can be selectively decomposed to magnesium carbonate at 100-200 °C to recover the NH_3 for reuse. In the present route, the total CO_2 sequestration capacity per tonne of blast furnace slag reached up to 316 kg, and 313 kg of Al-rich precipitate, 1000 kg of carbonated product containing CaCO_3 and SiO_2, and 304 kg of carbonated product containing calcium carbonate and magnesium carbonate were recovered simultaneously. These products can be used, respectively, as raw materials for the production of electrolytic aluminium, cement, and light magnesium carbonate to replace natural resources.展开更多
The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%...The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%-20% of the total heat resistance of cooling stave body, as for drilling duct type, the heat resistance of 2-6 mm water scale is about 88%-98% of the total heat resistance. Using drilling duct or full cast pipe can eliminate gas clearance and coating layer between pipes and cast iron body and reduce the heat resistance of the cooler sharply and improve the coefficient of heat transfer to a great extent. The water velocity within coolers can be kept at the 1evel of 0.5- 1 .5 m/s, the higher water velocity can not decrease the hot surface temperature, but can increase energy consumption for cooling water.展开更多
Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the micros...Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.展开更多
Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature...Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature under very high heat flux. Applying low heat re- sistance lining and staves cooler to BF is good for a layer of slag skull frozen on the hot surface of cooling stave. As long as the slag skull can stand, the furnace wall is stable and the heat loss of furnace does not increase. This is the basic principle for designing long campa- ignship BF.展开更多
基金National Natural Science Foundation of China (No. 51574067)the National High Technology Research and Development Program of China (No. 2012AA062302 and No. 2012AA062304)the Fundamental Research Funds for the Central Universities of China (No. N130602003)
文摘An innovative process of blast furnace(BF) operation involving charging with low-titanium vanadium–titanium magnetite carbon composite hot briquette(LVTM-CCB) was proposed for utilizing LVTM and conserving energy. In this study, the effect of LVTM-CCB charging ratio on the softening, melting, and dripping behaviors of the mixed burden was explored systemically, and the migration of valuable elements V and Cr was extensively investigated. The results show that with increasing LVTM-CCB charging ratio, the softening interval T_(40)- T_4 increases from 146.1°C to 266.1°C, and the melting interval T_D- T_S first decreases from 137.2°C to 129.5°C and then increases from 129.5°C to 133.2°C. Moreover, the cohesive zone becomes narrower and then wider, and its location shifts slightly downward. In addition, the recovery ratios of V and Cr in dripped iron first increase and then decrease, reaching maximum values of 14.552% and 28.163%, respectively, when the charging ratio is 25%. A proper LVTM-CCB charging ratio would improve the softening–melting behavior of the mixed burden; however, Ti(C,N) would be generated rapidly in slag when the charging ratio exceeds 25%, which is not favorable for BF operation. When considering the comprehensive softening–melting behavior of the mixed burden and the recovery ratios of V and Cr, the recommended LVTM-CCB charging ratio is 20%.
文摘The effect of hydrogen injection on blast furnace operation and carbon dioxide emissions was simulated using a 1D steady-state zonal model.The maximum hydrogen injection rate was evaluated on the basis of the simulation of the vertical temperature pattern in the blast furnace with a focus on the thermal reserve zone.The effects of blast temperature and oxygen enrichment were also examined to estimate coke replacement ratio,productivity,hydrogen utilization efficiency,and carbon dioxide emission reduction.For blast temperature of 1200℃,the maximum hydrogen injection rate was 19.0 and 28.3 kg of H_(2)/t of hot metal(HM)for oxygen enrichment of 2vol%and 12vol%,respectively.Results showed a coke replacement ratio of 3-4 kg of coke/kg of H_(2),direct CO_(2) emission reduction of 10.2%-17.8%,and increased productivity by up to 13.7%depending on oxygen enrichment level.Increasing blast temperature further reduced the direct CO_(2) emissions.Hydrogen utilization degree reached the maximum of 0.52-0.54 H_(2)O/(H_(2)O+H_(2)).The decarbonization potential of hydrogen injection was estimated in the range from 9.4 t of CO_(2)/t of H_(2) to 9.7 t of CO_(2)/t of H_(2).For economic feasibility,hydrogen injection requires revolutionary progress in terms of low-cost H_(2) generation unless the technological change is motivated by the carbon emission cost.Hydrogen injection may unfavorably affect the radial temperature pattern of the raceway,which could be addressed by adopting appropriate injection techniques.
基金the National Key R&D Program of China(No.2022YFE0208100)the National Natural Science Foundation of China(No.5274316)+1 种基金the Key Research and Development Plan of Anhui Province,China(No.202210700037)the Major Science and Technology Project of Xinjiang Uygur Autonomous Region,China(No.2022A01003).
文摘The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile content of biochar ranged from 16.19%to 45.35%,and the alkali metal content,ash content,and specific surface area were significantly reduced.The optimal route for biochar pro-duction is hydrothermal carbonization-pyrolysis(P-HC),resulting in biochar with a higher calorific value,C=C structure,and increased graphitization degree.The apparent activation energy(E)of the sample ranges from 199.1 to 324.8 kJ/mol,with P-HC having an E of 277.8 kJ/mol,lower than that of raw biomass,primary biochar,and anthracite.This makes P-HC more suitable for blast furnace injection fuel.Additionally,the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits.P-HC of-fers the highest potential for carbon emission reduction,capable of reducing emissions by 96.04 kg/t when replacing 40wt%coal injec-tion.
基金Funded by the National Natural Science Foundation of China Youth Fund(No.52204419)the Liaoning Provincial Natural Science Foundation(No.2022-BS-076)the Guangxi Science and Technology Major Project(No.2021AA12013)。
文摘To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.
基金the National Natural Science Foundation of China(62273359)the General Project of Hunan Natural Science Foundation of China(2022JJ30748)the National Major Scientific Research Equipment of China(61927803)。
文摘Blast furnace(BF)burden surface contains the most abundant,intuitive and credible smelting information and acquiring high-definition and high-brightness optical images of which is essential to realize precise material charging control,optimize gas flow distribution and improve ironmaking efficiency.It has been challengeable to obtain high-quality optical burden surface images under high-temperature,high-dust,and extremelydim(less than 0.001 Lux)environment.Based on a novel endoscopic sensing detection idea,a reverse telephoto structure starlight imaging system with large field of view and large aperture is designed.Combined with a water-air dual cooling intelligent self-maintenance protection device and the imaging system,a starlight high-temperature industrial endoscope is developed to obtain clear optical burden surface images stably under the harsh environment.Based on an endoscope imaging area model,a material flow trajectory model and a gas-dust coupling distribution model,an optimal installation position and posture configuration method for the endoscope is proposed,which maximizes the effective imaging area and ensures large-area,safe and stable imaging of the device in a confined space.Industrial experiments and applications indicate that the proposed method obtains clear and reliable large-area optical burden surface images and reveals new BF conditions,providing key data support for green iron smelting.
基金the Postdoctoral Research Foundation of China (No.2017M611799)the Basic Research Program of Jiangsu Province (No.BK20190690)。
文摘A blast furnace slag zeolite(BFSZ)material was successfully synthesized from BFS by alkaline fusion and hydrothermal treatment.Via the analyses of XRD,FT-IR,FE-SEM,XRF,CEC and BET surface area measurement,when zeolite was synthesized at a crystallization temperature of 100℃with initial Si/Al ratio of 1:1,the main composition in the product is Na-A zeolite.Under the above conditions,the BFSZ was synthesized with CEC of 3.06 meq/g and maximum BET surface area of 37.55 m^(2)·g^(-1).Moreover,the incorporating of BFS-derived minor metals(such as Mg,Fe,and Ca)are found to be of little importance for the synthesis of BFSZ.Thus the obtained BFSZ material has a great adsorption performance for removing Mn^(2+),Cu^(2+),and NH_(4)^(+)ions diluted in water,owing to the higher CEC.
基金supported in part by the National Natural Science Foundation of China(61933015)in part by the Central University Basic Research Fund of China under Grant K20200002(for NGICS Platform,Zhejiang University)。
文摘Due to the problems of few fault samples and large data fluctuations in the blast furnace(BF)ironmaking process,some transfer learning-based fault diagnosis methods are proposed.The vast majority of such methods perform distribution adaptation by reducing the distance between data distributions and applying a classifier to generate pseudo-labels for self-training.However,since the training data is dominated by labeled source domain data,such classifiers tend to be weak classifiers in the target domain.In addition,the features generated after domain adaptation are likely to be at the decision boundary,resulting in a loss of classification performance.Hence,we propose a novel method called minimax entropy-based co-training(MMEC)that adversarially optimizes a transferable fault diagnosis model for the BF.The structure of MMEC includes a dual-view feature extractor,followed by two classifiers that compute the feature's cosine similarity to representative vector of each class.Knowledge transfer is achieved by alternately increasing and decreasing the entropy of unlabeled target samples with the classifier and the feature extractor,respectively.Transfer BF fault diagnosis experiments show that our method improves accuracy by about 5%over state-of-the-art methods.
基金Funding Statement:This work was supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due to their environmental sustainability and the feasibility of immobilizing industrial waste.In this paper,steel slag(SS)fines were investigated as auxiliary materials of blast furnace slag(BFS)based geopolymer.The hydration heat properties,flowability,compressive strength,sorptivity coefficient,X-ray diffraction(XRD),and scanning electron microscopy(SEM)of the geopolymer pastes were determined.The results showed that the incorporation of SS weakened the reactivity of the BFS-based geopolymer paste and improved the flow values of the paste.The compressive strength of the geopolymer with 20%SS content reached 117 MPa at 28 d.The geopolymer specimens with high compressive strength showed a low sorptivity coefficient.The microscopic results showed that the addition of the appropriate amount of SS reduced the cracks,improved the density of the geopolymer,and produced a geopolymer composite with excellent mechanical properties.
文摘A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of iron-bearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.
基金acknowledged DEQ/IT/UFRRJ,FEG/UNESP-Guaratinguetáand EEL/USP-Lorena for their support in carrying out the analyses.
文摘Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal shock resistance lead these refractory materials to be used as channel linings of blast furnaces,where they are exposed to the attack by slag,molten steel,working cycles and sudden temperature changes between 25℃(room temperature)and 1520℃(the temperature of molten pig iron).In this work,microstructural changes in post-mortem aluminous refractory bricks were investigated by apparent porosity,X-ray diffraction analysis(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,and X-ray dispersion energy spectrometry(SEM/EDS).The results showed an increase in the apparent porosity and the bulk density and the presence of the phases mullite,sillimanite,alumina,and quartz in the post-mortem brick.Calcium and magnesium were not detected in the microstructure of the post-mortem brick,indicating that slags did not corrode these refractory materials.Therefore,the microstructural changes that occurred in the post-mortem bricks must be due to thermal cycling.In the X-ray diffraction(XRD)test,mullite,sillimanite,quartz,andα-alumina phases were identified.These results indicate that the aluminous refractory was obtained from sillimanite.In infrared spectroscopy(FTIR)it was possible to identify the vibration bands referring to the Si-O and Al-O bonds.The increase in the porosity is a result of cracks caused by work cycles at high temperatures and the temperature gradient to which the refractory was subjected during use.Through the micrograph it was possible to identify the presence of acicular mullite.The absence of magnesium and calcium in the microanalysis results by energy dispersed X-ray spectrometry(EDS)indicates that there was no infiltration by slag or liquid iron.These results indicate that the microstructural changes that occurred in the post-mortem aluminous refractory were of a thermal nature.
文摘A SiC assembled large block for blast furnace tuyeres was prepared using silicon carbide particles(3-1 and 1-0.088 mm)and fine powder(<0.088 mm),silicon powder(<0.088 mm),industrial carbon black(N990),microsilica,ρ-Al_(2)O_(3) powder,etc.as raw materials.The developed block was compared with a silicon nitride bonded silicon carbide brick,a self-bonded silicon carbide brick and an imported self-bonded silicon carbide block to analyze and evaluate their service performance.The results show that:(1)in the 0-100 mm zone,the SiC large block mainly consists ofβ-SiC and nitrides such as O'-SiAlON,β-SiAlON,α-Si_(3)N_(4),and Si_(2)N_(2)O,the bulk density is 2.68-2.70 g·cm^(-3),the apparent porosity is 14%-15%,and the material structure is uniform;(2)in the 0-100 mm zone,β-SiC nano-whiskers intercalate with nitrides;with the depth increasing,the number of flocculentβ-SiC nano-whiskers increases,while the number of nitrides decreases;when the depth reaches 150 mm or more,the main bonding phases areβ-SiC and mullite;(3)compared with the reference products,the developed SiC large block has a good basic performance,and after alkali corrosion,the mass change rate is-0.1%,which is obviously superior to the imported self-bonded silicon carbide and the homemade silicon nitride bonded silicon carbide materials.
文摘The article introduces the composition and working principle of the batching and weighing system underneath the blast furnace hearth.Besides,the shortcomings of the batching and weighing system during installation,debugging,and calibration,as well as the dynamic errors in the batching process are also analyzed.Corresponding solutions are then provided.
基金Item Sponsored by National Natural Science Foundation of China(50804008)Program for New Century Excellent Talents in University of China(NCET-08-0099)
文摘Blast furnace operation with hot burden charging was numerically simulated to preliminarily analyze its advantages and disadvantages.Multi-fluid blast furnace model was utilized to simulate hot burden charging operations under the conditions that the charging temperatures of pellet and coke were supposed separately or simultaneously as800℃.The results showed that,with hot burden charging,the furnace top temperature significantly increased in comparison to the conventional operation with cold burden charging.However,in-furnace temperature decreased,which decelerated the reduction rate of ferrous burdens.The concentrations of reducing gases were decreased in the furnace.The height of cohesive zone shifted downwards.When the charging temperatures of pellet and coke were simultaneously 800℃(PC800),coke rate,fuel rate and carbon emission rate were decreased by 13.4,22.1and19.25kg·t-1,respectively.The ratio of ore to coke,solid burden charging rate and hot metal productivity were increased by 4.79%,7.55kg·s-1 and 6.38%,respectively.Heat taken away by top gas and energy consumption per ton hot metal were increased by 68.97%and 6.40%,respectively.Generally speaking,hot burden charging was adverse to energy utilization of blast furnace.
基金financially supported by the National Key Research and Development Program of China (Nos. 2017YFB0304300 and 2017YFB0304303)the National Science Foundation of China (No. 51774032)the Chinese Fundamental Research Funds for the Central Universities (No. FRF-TP-17-086A1)
文摘The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimetric analysis. The experimental gas compositions and the corresponding temperature were chosen according to data reported for industrial BFs. The gasification behavior of coke was described by the Random Pore Model (RPM), Volumetric Model (VM), and Grain Model (GM). Results showed that the gas composition of the coke gasification zone in BF changes slightly and that the temperature is the most important factor affecting coke gasification. The lower activation energy of coke samples (Coke Reaction Index (CRI)>50) is due to the high Fe2O3 in the ash, lower degree of graphitization, and larger pore structure. In addition, the choice of kinetic model does not differ substantially in describing the gasification mechanism of coke in a BF.
基金financially supported by the Natural Science Foundation of China(No.51304014)the Natural Science Foundation of China and Baosteel(No.51134008)the National Basic Research Program of China(No.2012CB720401)
文摘A variety of techniques, such as chemical analysis, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, were applied to characterize the adhesion protective layer formed below the blast furnace taphole level when a certain amount of titanium-bearing burden was used. Samples of the protective layer were extracted to identify the chemical composition, phase assemblage, andistribution. Furthermore, the formation mechanism of the protective layer was determined after clarifying the source of each componenFinally, a technical strategy was proposed for achieving a stable protective layer in the hearth. The results show that the protective layemainly exists in a bilayer form in the sidewall, namely, a titanium-bearing layer and a graphite layer. Both the layers contain the slag phaswhose major crystalline phase is magnesium melilite(Ca_2Mg Si_2O_7) and the main source of the slag phase is coke ash. It is clearly determinethat solid particles such as graphite, Ti(C,N) and Mg Al_2O_4 play an important role in the formation of the protective layer, and the key factofor promoting the formation of a stable protective layer is reasonable control of the evolution behavior of coke.
基金financially supported by the National Natural Science Foundation of China (No. 51474018)
文摘The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of-43 μm accounting for 69.02 wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO_2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage(≤4 wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF_2 and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F-when used as reducing agents, leading to weaker effects of fluorite.
基金financial support of the National Key R&D Program of China(2016YFB0600904)
文摘Large quantities of CO_2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO_2 emission reduction and comprehensive utilisation of the solid waste. In this study, a recyclable extractant,(NH_4)_2SO_4, was used to extract calcium and magnesium from blast furnace slag(main phases of gehlenite and akermanite) by using low-temperature roasting to fix CO_2 through aqueous carbonation. The process parameters and efficiency of the roasting extraction, mineralisation, and Al recovery were investigated in detail. The results showed that the extractions of Ca, Mg, and Al can reach almost 100% at an(NH4)_2SO_4-to-slag mass ratio of 3:1 and at 370°C in 1 h. Adjusting the p H value of the leaching solution of the roasted slag to 5.5 with the NH_3 released during the roasting resulted in 99% Al precipitation, while co-precipitation of Mg was lower than 2%. The Mg-rich leachate after the depletion of Al and the leaching residue(main phases of CaSO_4 and SiO_2) were carbonated using(NH_4)_2CO_3 and NH_4HCO_3 solutions, respectively, under mild conditions. Approximately 99% of Ca and 89% of Mg in the blast furnace slag were converted into CaCO_3 and(NH_4)_2 Mg(CO_3)_2·4 H_2O,respectively. The latter can be selectively decomposed to magnesium carbonate at 100-200 °C to recover the NH_3 for reuse. In the present route, the total CO_2 sequestration capacity per tonne of blast furnace slag reached up to 316 kg, and 313 kg of Al-rich precipitate, 1000 kg of carbonated product containing CaCO_3 and SiO_2, and 304 kg of carbonated product containing calcium carbonate and magnesium carbonate were recovered simultaneously. These products can be used, respectively, as raw materials for the production of electrolytic aluminium, cement, and light magnesium carbonate to replace natural resources.
文摘The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%-20% of the total heat resistance of cooling stave body, as for drilling duct type, the heat resistance of 2-6 mm water scale is about 88%-98% of the total heat resistance. Using drilling duct or full cast pipe can eliminate gas clearance and coating layer between pipes and cast iron body and reduce the heat resistance of the cooler sharply and improve the coefficient of heat transfer to a great extent. The water velocity within coolers can be kept at the 1evel of 0.5- 1 .5 m/s, the higher water velocity can not decrease the hot surface temperature, but can increase energy consumption for cooling water.
基金financially supported by the Science and Technology Support Program of Sichuan Province (No.2014GZ0011)the Industry Promotion Project of Panzhihua City, China (No.2012CY-C-2)
文摘Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.
文摘Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature under very high heat flux. Applying low heat re- sistance lining and staves cooler to BF is good for a layer of slag skull frozen on the hot surface of cooling stave. As long as the slag skull can stand, the furnace wall is stable and the heat loss of furnace does not increase. This is the basic principle for designing long campa- ignship BF.
