Dust Distribution Study at the Blast Furnace Top Based on k-Sε-u_(p)Model

The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service life of detection equipment.The harsh environment inside a BF makes it difficult to describe the dust disthibution.This paper adresses this problem by proposing a dust distribution k-Sε-u_(p)model based on interphase(gas-powder)coupling.The proposed model is coupled with a k-Sεmodel(which describes gas flow movement)and a u_(p)model(which depicts dust movement).First,the kinetic energy equation and turbulent dissipation rate equation in the k-Sεmodel are established based on the modeling theory and single Green-function two scale direct interaction approximation(SGF-TSDIA)theory.Second,a dust particle mnovement u_(p)model is built based on a force analysis of the dust and Newton's laws of motion.Finally,a coupling factor that descibes the interphase interaction is proposed,and the k-Sε-u_(p)model,with clear physical meaning.ligorous mathematical logic,and adequate generality,is dleveloped.Siumulation results and o-site verification show that the k-Sε-u_(p)model not only has high precision,but also reveals the aggregate distribution features of the dust,which are helpful in optimizing the installation position of the detection equipment and imnproving its accuracy and service life.

Cross-upgrading of biomass hydrothermal carbonization and pyrolysis for high quality blast furnace injection fuel production:Physicochemical characteristics and gasification kinetics analysis

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.

Coke behavior with H_(2)O in a hydrogen-enriched blast furnace:A review

Hydrogen-enriched blast furnace ironmaking has become an essential route to reduce CO_(2)emissions in the ironmaking process.However,hydrogen-enriched reduction produces large amounts of H_(2)O,which places new demands on coke quality in a blast furnace.In a hydrogen-rich blast furnace,the presence of H_(2)O promotes the solution loss reaction.This result improves the reactivity of coke,which is 20%-30%higher in a pure H_(2)O atmosphere than in a pure CO_(2)atmosphere.The activation energy range is 110-300 kJ/mol between coke and CO_(2)and 80-170 kJ/mol between coke and H_(2)O.CO_(2)and H_(2)O are shown to have different effects on coke degradation mechanisms.This review provides a comprehensive overview of the effect of H_(2)O on the structure and properties of coke.By exploring the interactions between H_(2)O and coke,several unresolved issues in the field requiring further research were identified.This review aims to provide valuable insights into coke behavior in hydrogen-rich environments and promote the further development of hydrogen-rich blast furnace ironmaking processes.

A Novel Sensing Imaging Equipment Under Extremely Dim Light for Blast Furnace Burden Surface:Starlight High-Temperature Industrial Endoscope

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.

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

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

Extraction of Valuable Metals from Titanium-bearing Blast Furnace Slag by Acid Leaching

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.

Analysis and Prospect of Waste Heat Utilization from Blast Furnace Slag Flushing

Estimating the residual heat of blast furnace slag flushing in China,classifying and introducing the current proposed methods of slag flushing waste heat utilization,and listing existing cases.In order to better save energy and water in the slag flushing process of blast furnaces,an ideal comprehensive cascade utilization system scheme for annual recovery of waste heat is proposed.Based on the measured waste heat data of a steel plant,design calculations are carried out to further analyze the economic feasibility of the new scheme and provide reference for its promotion and application.

Mathematical model of burden distribution for the bell-less top of a blast furnace

Due to the difficulty in measuring the burden trajectory directly in an actual blast furnace （BF）, a mathematical model with Coriolis force and gas drag force considered was developed to predict it. The falling point and width of the burden flow were obtained and analyzed by the model, the velocities of particles at the chute end were compared with and without the existence of Coriolis force, and the effects of chute length and chute torque on the falling point were also discussed. The simulation results are in good agreement with practical measurements with laser beams in a 2500 m3 BF.

Synthesis,Characterization of NaA Zeolite from Blast Furnace Slag(BFS)via Alkaline Fusion and Hydrothermal Treatment

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.

Minimax entropy-based co-training for fault diagnosis of blast furnace

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.

Efficient Use of Steel Slag in Alkali-Activated Blast Furnace Slag Based Geopolymer

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.

Post-mortem Microstructural Study of Aluminous Refractory Brick Used in Channels of Blast Furnaces

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.

Preparation and Properties of SiC Assembled Large Block for Blast Furnace Tuyeres

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.

Research on Weighing System and Debugging Technology for Batching Under Blast Furnace Ore Tank

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.

Particle size segregation in hopper at a bell-less top blast furnace with parallel hoppers

Owing to a certain angle existing between a belt conveyor and the parallel hoppers,and the hoppers localizing away from the centerlines of a blast furnace,particles size segregation is likely to happen in a bell-less top blast furnace with parallel hoppers.Mastering the law of particles size segregation in hoppers could help to choose better charging parameters and optimize production and technical indices.As for the previous works on burden segregation at a bell-less top blast furnace with parallel hoppers,more attention was paid to the falling point segregation and the circumferential mass flow segregation while charging from the tilting chute,but ignoring the particle size segregation in burden hoppers as burden falls from a belt conveyor,which is the right basis of analyzing the former,and plays a significant role in controlling the gas distribution in the blast furnace.The present work takes ternary mixtures of coke in three different particle sizes to simulate the size segregation of the coke charged into the hoppers by experiments.The effect of the main striking point on size segregation is also investigated.The research shows that there exists a good linear relation between segregation coefficient k and the dimensionless main striking point when using the equation C = C_0~k to express the degree of size segregation in hoppers.The linear relation is proposed for the first time and provides a new way to predict the size segregation in hoppers,which forms a theoretical basis and technical support for reducing the size segregation degree in hoppers.

Mechanism of zinc damaging to blast furnace tuyere refractory

The phenomena of tuyere upward-warp have been found at No.6 blast furnace in Kunming Steel Company China after its blow-in, which has made a great impact on the practical production of the furnace. Thus, a number of efforts have been made to elucidate the mechanism of this phenomenon. The results of investigation and tests revealed that the enrichment and expansion of zinc in the tuyere bricks is the main factor leading to the tuyere upward-warp. The eroding behavior of zinc is that the inner structure of the tuyere bricks turns from dense to loose with entering, enriching and expanding of zinc, which forms spot-like→stripe-like→ditch-like→vein-like→tumorlike eroding passage. Additionally, it is found that the sequence of deleterious ele- ments entering the tuyere refractory is K, Na, Zn and Pb, respectively. Finally, the phenomena and process of zinc crystallization and growth in the refractory have been clearly observed and recorded during this investigation.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Formation mechanism of the protective layer in a blast furnace hearth

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（Ca2Mg Si2O7） 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 Al2O4play 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.

Simultaneous preparation of TiO2 and ammonium alum,and microporous SiO2 during the mineral carbonation of titanium-bearing blast furnace slag

In this study,a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum,and microporous silicon dioxide from titanium-bearing blast furnace slag(TBBF slag)was proposed,which is comprised of(NH4)2 S04 roasting,acid leaching,ammonium alum crystallization,silicic acid flocculation and Ti hydrolysis.The effects of relevant process parameters were systematically investigated.The re sults showed that under the optimal roasting and leaching conditions about 85%of titanium and 84.6%of aluminum could be extracted while only 30%of silicon entered the leachate.84%of Al^3+was crystallized from the leachate in the form of ammonium aluminum sulfate dodecahydrate with a purity up to 99.5 wt%.About 85%of the soluble silicic acid was flocculated with the aid of secondary alcohol polyoxyethylene ether 9(AEO-9)to yield a microporous SiO2 material(97.4 wt%)from the crystallized mother liquor.The Al-and Si-depleted solution was then hydrolyzed to generate a titanium dioxide(99.1 wt%)with uniform particle size distribution.It was figured out that approximately 146 kg TiO2 could be produced from 1000 kg of TBBF slag.Therefore,the improved process is a promising method for industrial application.

Numerical Simulation of Innovative Operation of Blast Furnace Based on Multi-Fluid Model

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.