The service life of refractory brick in the slag tapping hole of gasifiers is a significant concern for long-term and stable operation.This study examined the damage mechanism of high chromia refractory of four commer...The service life of refractory brick in the slag tapping hole of gasifiers is a significant concern for long-term and stable operation.This study examined the damage mechanism of high chromia refractory of four commercial coal-water slurry gasifiers with their corresponding gasification coal samples and the corroded refractory bricks in the slag tapping hole of the gasifier.The slag characteristic,including crystallization and viscosity-temperature of four gasification coal samples were analyzed.The results revealed that the low viscosity slag could lead to more severe damage to refractory bricks.Given the risk of slag crystallization,it is recommended to establish a safe slag tapping temperature range should be set as tICT(initial crystallization temperature)−t_(2.5) when tICT is higher than t_(25).Upon examining interior morphology of these corroded refractory bricks,some cracks were observed within them.The chemical composition of molten slag was analyzed using SEM-EDS.However,XRD results found no spinel containing zirconium in these cracks.This suggests that the emergence of these cracks are mainly attributed to the molten slag penetration and the subsequent reaction with the refractory material.The difference in thermal expansion between the newly formed substances and refractory material is critical in forming these cracks.Furthermore,SEM-EDS analysis was also conducted on the slag-aggregate and the slag-matrix interface.The results reveal that the reduction in Cr_(2)O_(3) content is the earliest characteristic of damage in high chromia refractories.A proposed damage mechanism of refractory brick suggests that the matrix and aggregate of high chromia refractory are initially compromised because of the reduced Cr_(2)O_(3) content.Subsequently,the molten slag penetrates the interior of the refractory brick,forming new substances,leading to damage caused by the difference in thermal expansion between the new substances and the refractory brick.Understanding and preventing the reduction of Cr_(2)O_(3) content is vital to prolonging the service life of refractory brick in the slag tapping hole of the gasifier based on this damage mechanism.展开更多
In order to examine the flow state of the steel-slag interface in a thin slab mold at high casting speed,a flexible thin slab casting mold and a novel five-hole nozzle were investigated.The maximum velocity and fluctu...In order to examine the flow state of the steel-slag interface in a thin slab mold at high casting speed,a flexible thin slab casting mold and a novel five-hole nozzle were investigated.The maximum velocity and fluctuation height of the steel-slag interface in the mold served as the evaluation criteria.Numerical simulation techniques,including large eddy simulation and volume of fluid,were employed to develop a two-phase flow model of liquid steel and slag.This model facilitated the analysis of the fluctuation behavior of the steel-slag interface and the mechanisms of slag entrapment.The results indicated that maintaining the stability of the steel-slag interface could be achieved by ensuring that the maximum velocity did not exceed 0.30 m s^(-1)or that the wave height remained below 30 mm.The relationship between the maximum velocity and wave height of the steel-slag interface was established by analyzing different casting speeds.Slag entrapment occurred when the maximum velocity exceeded the critical value.The critical velocity for shear slag entrapment was 0.485 m s^(-1),while for vortex slag entrapment,it was when the velocity of the swirl center reached 0.235 m s^(-1).Electromagnetic braking proved effective in controlling flow in the mold,reducing fluctuations in the steel-slag interface,preventing slag entrapment,and maintaining the position of the interface.Furthermore,it facilitated the control of the uniformity and stability of slag movement along the outer wall of the submerged entry nozzle and the copper wall of the mold.展开更多
As the speeds of trains increase,higher demands are placed on brake materials.In order to overcome the thermal degradation phenomenon of brake pads during high-speed braking,we prepared copper fiber reinforced alkali-...As the speeds of trains increase,higher demands are placed on brake materials.In order to overcome the thermal degradation phenomenon of brake pads during high-speed braking,we prepared copper fiber reinforced alkali-activated slag composite(AASC)friction materials by hot-pressing method,using slag as matrix,Na_(2)SiO_(3)·9H_(2)O as alkali excitant,copper fiber as reinforcement,and graphite as friction modifier.The results show that the AASC prepared by hot-pressing method has undergone alkali-activated reaction and has geopolymer amorphous characteristics as the conventional cast molding AASC by XRD analysis.The addition of copper fibers can improve the mechanical strength and toughness of the composites substantially,and the AASC has the highest flexural strength,compressive strength and impact toughness when the volume fraction of copper fibers reaches 25 vol%.Toughening mechanisms such as drawing,bridging and crack deflection of copper fibers in composites were analyzed by SEM morphology.Addition of appropriate amount of graphite to AASC can effectively reduce the wear rate and improve the stability of the material friction coefficient.The coefficient of friction also remains stable in the high-speed friction experiments without thermal degradation.Therefore,copper fiber reinforced AASC friction materials prepared by hot-pressing method has good mechanical and friction properties.展开更多
The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusi...The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusions was characterized by the Kullback-Leibler(KL)divergence.The slag structure analysis revealed that the[AlO]tetrahedral structure was the primary network structure in the slag.With increasing the CaO content,the non-bridge oxygen(NBO)content in the slag structure increases,and the bridge oxygen(BO)content decreases,thereby reducing the complexity of the slag network structure.Raman spectroscopy detection verifies the results of the MD simulations.The results indicated that the dissolution rate of alumina inclusions accelerates with increasing the CaO content in the slag,owing to the reduced complexity of the slag network structure and the enhanced interatomic interactions.The simulation results for the dissolution of alumina inclusions were consistent with theoretical calculations based on the slag inclusion capacity and the dimensionless dissolution rate of inclusions.Radial distribution function analysis demonstrated that the interaction between atoms in the slag system and alumina inclusions strengthens,increasing the dissolution rate of alumina inclusions.The[AlO_(6)]octahedral structure of the alumina inclusions is disrupted,forming BO structures,which in turn enhances the complexity of the slag network structure,slowing the dissolution rate of alumina inclusions.In contrast,the slag system with a higher CaO content has a relatively simpler network structure,promoting faster alumina inclusion dissolution.展开更多
The viscosity of refining slags plays a critical role in metallurgical processes.However,obtaining accurate viscosity data remains challenging due to the complexities of high-temperature experiments,often relying on e...The viscosity of refining slags plays a critical role in metallurgical processes.However,obtaining accurate viscosity data remains challenging due to the complexities of high-temperature experiments,often relying on empirical models with limited predictive capabilities.This study focuses on the influence of optical basicity on viscosity in CaO-Al_(2)O_(3)-based refining slags,leveraging machine learning to address data scarcity and improve prediction accuracy.An automated framework for algorithm integration,parameter tuning,and evaluation ranking framework(Auto-APE)is employed to develop customized data-driven models for various slag systems,including CaO-Al_(2)O_(3)-SiO_(2),CaO-Al_(2)O_(3)-CaF_(2),CaO-Al_(2)O_(3)-SiO_(2)-MgO,and CaO-Al_(2)O_(3)-SiO_(2)-MgO-CaF_(2).By incorporating optical basicity as a key feature,the models achieve an average validation error of 8.0%to 15.1%,significantly outperforming traditional empirical models.Additionally,symbolic regression is introduced to rapidly construct domain-specific features,such as optical basicity-like descriptors,offering a potential breakthrough in performance prediction for small datasets.This work highlights the critical role of domain-specific knowledge in understanding and predicting viscosity,providing a robust machine learning-based approach for optimizing refining slag properties.展开更多
A full-sectional microstructure characterization method was developed to investigate the formation of coarse slag rims during the continuous casting of hypo-peritectic steel.The cross-sectional microstructural analysi...A full-sectional microstructure characterization method was developed to investigate the formation of coarse slag rims during the continuous casting of hypo-peritectic steel.The cross-sectional microstructural analysis of typical slag rims for two highly crystalline powders revealed that their formation was primarily driven by the solidification of the liquid slag.Distinct differences were observed in the microstructures of slag rims from the two powders.Powder A(characterized by a higher breaking temperature and viscosity)displayed alternating lamellar microstructures of coarse and fine phases,with the coarse phases composed of akermanite-gehlenite transition phases.In contrast,powder B(with a lower breaking temperature and viscosity)predominantly comprised regular akermanite-gehlenite crystals interspersed with a certain amount of glassy phases.Numerical simulations of a three-phase fluid flow coupled with heat transfer indicate that slag rim formation correlates with mold oscillation.Solidification of the liquid slag at the slag rim front predominantly occurs during the negative stroke of the mold oscillation.The average heating rate during the ascending stage of the mold reaches approximately 100 K·s^(−1),whereas the average cooling rate during the descending stage attains 400 K·s^(−1).This temperature variation leads to the formation of lamellar microstructures,whereas the ascending stage promotes the formation of coarse structures and thicker slag rims.Based on the powder properties,two distinct formation pathways exist for highly crystalline mold powders.For the powders with a higher breaking temperature,higher viscosity,and narrower solidification range(powder A),coarse microstructures and thicker slag rims were preferentially formed.For powders with lower breaking temperature and viscosity and wider solidification ranges(powder B),the liquid slag resisted rapid solidification,and the extended mushy zone allowed the partial liquid slag to persist at the slag rim front,promoting the formation of a thin slag rim.This study enhances the understanding of slag rim formation in highly crystalline mold powders and provides critical insights into the control of longitudinal surface cracks in hypo-peritectic steel.展开更多
Curing temperature significantly affects the pozzolanic reaction kinetics of phosphorous slag(PS),thereby governing the early-age(7 d)hydration behavior of PS composite binders at 20,30,and 60℃.The Krstulovic-Dabic k...Curing temperature significantly affects the pozzolanic reaction kinetics of phosphorous slag(PS),thereby governing the early-age(7 d)hydration behavior of PS composite binders at 20,30,and 60℃.The Krstulovic-Dabic kinetic model was applied to identify three characteristic processes:nucleation and growth(NG),phase boundary interaction(I),and diffusion(D).Control mixtures containing inert quartz powder with comparable particle size distributions were prepared for comparison.Pore characteristics of hardened PS pastes at different temperatures were analyzed via mercury intrusion porosimetry,while hydration products were characterized using X-ray diffraction(XRD)and thermogravimetric analysis(TG-DTG).The experimental results indicate that the retarding effect of PS on early cement hydration outweighs its accelerating effect,attributed to the combined influence of nucleation and dilution,with retardation decreasing as temperature increases.PS exhibits early reactivity and continuously consumes calcium hydroxide through the pozzolanic reaction,as evidenced by stable phase assemblages accompanied by reduced CH content in XRD and TG-DTG analyses.At 20℃,increasing PS content maintains the NG→I→D mechanism but slows reaction rates across all stages.Elevated temperatures significantly accelerate the NG process,shifting the dominant mechanism from NG toward D.Simultaneously,enhanced PS reactivity contributes to a refined pore structure and improved compressive strength.展开更多
Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates wi...Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates with varying manganese concentrations(VL-cMn)were prepared through calcium,a calcium-manganese composite,and manganese-based roasting of vanadium slag(VS)to investigate the influence of manganese on vanadium precipitation behavior during hydrolysis precipitation(HP)and ammonium salt precipitation(AP),as well as the microscopic characteristics and purity of the resulting V_(2)O_(5) products.The results showed that increasing the pH mitigated the negative effects of Mn on the V precipitation rate during HP.However,as the manganese concentration increased from 5.69 to 15.38 g/L,the V precipitation rate gradually declined at higher temperatures and longer reaction times.The precipitates exhibited increased microstructural density,which might had contributed to the formation of Mn-bearing phases.Additionally,the average grain size of V_(2)O_(5) was reduced and the particles were increasingly agglomerated,leading to a 2.55%decrease in product purity.For AP,as manganese concentration increased,raising the pH counteracted the negative impact of Mn on the V precipitation rate and reduced the required amount of ammonium sulfate.Moreover,Mn was unevenly adsorbed on the surface of the precipitates.Although V_(2)O_(5) grains gradually shrank and became denser,there was no significant effect on the final product purity,which remained above 99.3%.In conclusion,roasting with added manganese salts influenced the hydrolysis of vanadium but had no significant effect on acidic ammonium salt precipitation.展开更多
The iron and steel industries generate large amounts of unavoidable CO_(2)emissions as well as considerable quantities of slags.More than one-half of the emitted CO_(2)is produced in blast furnaces during ironmaking,a...The iron and steel industries generate large amounts of unavoidable CO_(2)emissions as well as considerable quantities of slags.More than one-half of the emitted CO_(2)is produced in blast furnaces during ironmaking,and thus it is meaningful to use blast furnace slags to capture CO_(2)while addressing the byproducts and flue gas of ironmaking.Mineral carbonation of slags is a promising route to achieve carbon neutrality and effective slag utilization.To exploit slag more effectively and capture CO_(2)in flue gas,an in-depth investigation into the carbonation of blast furnace slags generated with different cooling methods was conducted.The effects of the solid–liquid ratio and introduced CO_(2)concentration on carbonation were determined.The CO_(2)uptake capacity of air-cooled slag(0.04 g/g)was greater than that of water-quenched slag.The CO_(2)uptake capacities of the two slags were comparable with those of slags in previous works,indicating the potential of the two slags for CO_(2)sequestration and utilization even with low-energy input and this fact suggests that this process is feasible.展开更多
Metallurgical slag is a waste or by-product of the metallurgical process,and its improper disposal can pose negative environmental impacts,including groundwater and soil contamination.The composition and properties of...Metallurgical slag is a waste or by-product of the metallurgical process,and its improper disposal can pose negative environmental impacts,including groundwater and soil contamination.The composition and properties of metallurgical slag are complex,which is usually difficult to use or process directly and requires special treatment and utilization methods.Taking converter slag and blast furnace slag as examples,the research frontiers and development potential were primarily discussed and analyzed in three aspects:the recycling within and outside metallurgical slag plants,the extraction and utilization of thermal energy from metallurgical slag,and the functionalization and social application of metallurgical slag.The metallurgical slag waste heat recovery includes chemical methods and physical methods.Among them,the physical method currently most used was centrifugal granulation to recover heat.Chemical laws could recover hydrogen through the waste heat of metallurgical slag,which could save fuel and reduce CO_(2) generated by fuel combustion.Metallurgical slag is rich in alkaline metal oxides,which can undergo a carbonation reaction with CO_(2) to achieve carbon sequestration in metallurgical slag.Elements such as iron,phosphorus,and silicon contained in metallurgical slag could be used in soil conditioners,cement raw materials,and wastewater treatment.For example,the phosphorus element in the slag could be extracted by melt modification followed by acid leaching and used as a raw material for phosphate fertilizer.Therefore,under the background of China’s carbon neutrality goal,it is important to develop the key technologies of waste heat utilization of metallurgical slag and carbon sequestration of metallurgical slag.展开更多
High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase co...High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase compositions were measured by electron probe microanalysis(EPMA).A series of pseudo-ternary and pseudo-binary phase diagrams are constructed to demonstrate their applications in copper smelting process and evaluation of the thermodynamic database.Spinel and tridymite are identified to be the major primary phases in the composition range related to the copper smelting slags.It is found that the operating window of the smelting slag is primarily determined by w_(Fe)/w_(SiO_(2))ratio in the slag.Both MgO and Al_(2)O_(3)in the slag reduce the operating window which requires extra fluxing agent to keep the slag to be fully liquid.Complex spinel solid solutions cause inaccurate predictions of the current thermodynamic database.展开更多
Low-carbon alkali-activated slag(AAS)is among the most common alkali-activated materials(AAMs).To further lower CO_(2) emissions and optimize the material system,we proposed a scheme of using phosphorous slag(PS)to su...Low-carbon alkali-activated slag(AAS)is among the most common alkali-activated materials(AAMs).To further lower CO_(2) emissions and optimize the material system,we proposed a scheme of using phosphorous slag(PS)to substitute ground granulated blast-furnace slag(GGBS)in sodium carbonate(NC)activated slag system.we conducted a systematic study on the mechanical properties of the NC-activated slag/PS blends at normal temperature and examined the influences of different substitution amounts of phosphorus slag and NC equivalents on the performance of the material system.The hydration process was analyzed using hydration flow and chemical shrinkage.The hydration products were characterized via XRD and TGA.Moreover,the pore structure and pH value were also analyzed.When the substitution dosage of PS was not greater than 30%,the 3 d compressive strength of the systems was improved to a certain degree.However,in the medium and later periods,the compressive strength of the systems was slightly lower than that of the control group.The 90 d compressive strength of the control group 4SC-0% was 47.6 MPa,which was 4.0 MPa lower than the 28 d one of itself,presenting a strength retrogression phenomenon,while all the test groups demonstrated a continuous growth law.When the substitution dosage of PS was not more than 30%,the hydration reaction of the AAS system was facilitated,whereas when the substitution amount was 50%,the hydration of the system was conspicuously slowed down.The incorporation of phosphorous slag was capable of enhancing the volume stability of the material system.The hydration products of this system were likely to be manasseite,calcite,and C-S-(A)-H.When the incorporation amount of phosphorous slag increased,the quantity of the hydration products reduced,which might result in the generation of C-N-S-A-H.The study proposed the methodology for designing weak base-activated slag/PS.展开更多
In the Pidgeon process involving a vertical pot,bonded slag pellets occasionally emerge at the bottom of the reduction pot,impeding smooth slag discharge.To reveal the formation mechanism of the bonded slag pellets,th...In the Pidgeon process involving a vertical pot,bonded slag pellets occasionally emerge at the bottom of the reduction pot,impeding smooth slag discharge.To reveal the formation mechanism of the bonded slag pellets,thermodynamic calculations,X-ray diffraction(XRD),X-ray fluorescence spectrometry(XRF),electron probe microanalyzer(EPMA),X-ray photoelectron spectroscopy(XPS),and differential scanning calorimetry(DSC)were employed.The bonded slag pellets mainly comprise MgO,CaSi_(2),CaO,and Ca2SiO_(4).CaSi_(2) in the bonded slag pellets is attributed to the reduction reaction between Si and CaO,yielding liquid CaSi_(2).Simultaneously,the reaction between CaSi_(2) and MgO,which will typically produce Mg vapor,is inhibited,resulting in the accumulation of CaSi_(2).Owing to the solid-liquid transition of CaSi_(2),this process culminates in the bonding of slag pellets.This study can guide the Pidgeon process optimization,enabling mitigation of the“dead pot”issue,thereby enhancing efficiency and reducing costs.展开更多
Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-...Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-temperature nickel-iron blast furnace molten slag(NBFS)was investigated.The results show that the flow temperature of the slag decreases with the increase in the proportion of SSPS.In a certain range,the flow temperature decreases by about 7℃ when the proportion of SSPS increases by 1%.The computational results from FactSage indicate that the addition of SSPS leads to a reduction in MgO content and an increase in CaO and CaSO_(4) contents,which are the reasons for the decrease in the flow temperature.Mortar blocks were prepared by mixing the slag powder prepared by water-quenched slag drying ball milling with 425 Portland cement in a certain proportion.As the proportion of SSPS increased from 0 to 5%,the 7-day strength of mortar blocks increased from 22.32 to 26.98 MPa,and the 28-day strength increased from 37.28 to 41.43 MPa.The 28-day activity index is above 75%,and its activity index meets the requirements of S75 ground granulated blast furnace slag.The industrial application program in the nickel-iron blast furnace with a volume of 550 m^(3) was also put forward,which provides a new way for realizing the resource utilization of SSPS.展开更多
Carbon dioxide (CO_(2)) mineralization technology has attracted significant attention, due tothe synergistic terminal treatment of CO_(2) and industrial waste. The combined CO_(2) mineralizationprocess with steel ente...Carbon dioxide (CO_(2)) mineralization technology has attracted significant attention, due tothe synergistic terminal treatment of CO_(2) and industrial waste. The combined CO_(2) mineralizationprocess with steel enterprises is a promising route to simultaneously address CO_(2)emissions and SS treatment. Recently, a serial of the relevant work focus on a single type ofsteel slag (SS), and the understanding of CO_(2) absorption by mineralization of various SS isvery lacking.Meanwhile, it is urgent requirement for systematic summary and discussion onhow to make full use of the mineralized products produced after the mineralization of CO_(2)in SS. This review aims to investigate the progress of CO_(2) mineralization using SS, includingthe potential applications of mineralization products, as well as the environmental impactand risk assessment ofmineralization product applications. Currently, the application of SSmineralization products is primarily focused on their use as construction materials with loweconomic value. With usage of the mineralization products for ecological restoration (e.g.sandy soil remediation) was treated as an advanced route, but still remaining challenge infunctional materials preparation, and its technical economy and possible hazards need tobe further explored by long-term experimental tests.展开更多
In the steel slag-based mine backfill cementitious material systems,the hydration reaction mechanisms and synergistic effects of steel slag(SS),granulated blast furnace slag(GBFS),and desulfurization gypsum(DG)are cru...In the steel slag-based mine backfill cementitious material systems,the hydration reaction mechanisms and synergistic effects of steel slag(SS),granulated blast furnace slag(GBFS),and desulfurization gypsum(DG)are crucial for performance optimization and regulation.However,existing studies have yet to fully reveal the underlying synergistic mechanisms,which limits the application and promotion of high SS content in mine backfill and low-carbon building materials.This study systematically explores the synergistic effects between various solid wastes and their regulation of the hydration process in the SS-based cementitious system through multi-scale characterization techniques.The results show that GBFS,by releasing active Si^(4+)and Al^(3+),triggers a synergistic activation effect with Ca^(2+)provided by SS,promoting the formation of C-S-H gel and ettringite,significantly optimizing the hardened paste microstructure.When the GBFS content reaches 30%,the C-S-H content increases by 40.8%,the pore size distribution improves,the proportion of large pores decreases by 68.7%,and the 90-day compressive strength increases to 5 times that of the baseline group.The sulfate activation effect of DG accelerates the hydration of silicate minerals,but excessive incorporation(>16%)can lead to microcracks caused by the expansion of AFt crystals,resulting in a strength reduction.Under the synergistic effect of 8%DG and 30%GBFS,the hydration reaction is most intense,with the peak heat release rate reaching 0.92 mW/g and the cumulative heat release amount being 240 J/g.By constructing a“SS-GBFS-DG-cement”quaternary synergistic system(mass ratio range:SS:GBFS:cement:DG=(50–62):(20–40):10:(8–12)),the matching of active components in high-content SS systems was optimized,significantly improving microstructural defects and meeting engineering application requirements.This study provides a theoretical basis for the component design and performance regulation of high-content SS-based cementitious materials.展开更多
China is the world’s largest producer of vanadium products,whose major vanadium resource is vanadium slag obtained by smelting vanadium−titanium magnetite ores.The vanadium extraction techniques from vanadium slag ha...China is the world’s largest producer of vanadium products,whose major vanadium resource is vanadium slag obtained by smelting vanadium−titanium magnetite ores.The vanadium extraction techniques from vanadium slag have progressed stepwise toward greenization during the past 30 years in China.This review has systematically summarized these developments and classified the developments into three stages.The early stage is the efficient vanadium extraction techniques such as the sodium roasting−water leaching technique.The developed stage is the clean vanadium extraction techniques including the calcification roasting−acid leaching technique and sub-molten salt technique.The advanced stage is the green vanadium extraction techniques,for example the magnesiation roasting−acid leaching technique.The mechanisms,advantages and disadvantages of industrially applied and literature reported vanadium extraction techniques in each development stage are elaborated from multiple perspectives.Finally,future development directions are pointed out,aiming to inspire green extraction technique of vanadium worldwide.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
Magnesium phosphate cements(MPC)have shown promising applications in many fields,but high raw material prices hinder their development.The production of salt lake MPC(SLMPC)from magnesium slag(MS),a byproduct of lithi...Magnesium phosphate cements(MPC)have shown promising applications in many fields,but high raw material prices hinder their development.The production of salt lake MPC(SLMPC)from magnesium slag(MS),a byproduct of lithium extraction from salt lakes,offers significant environmental and economic advantages.In this study,a low-cost magnesia raw material was obtained through the calcination of MS,which was subsequently utilized in conjunction with KH_(2)PO_(4) to prepare SLMPC.The changes in hydration products,microscopic morphology,solution pH value,and TG content during the SLMPC curing process,and the hydration kinetics equation and model were used to study the hydration processes of SLMPC.The results show that the outcome indicates that the SLMPC system entered the accelerated reaction stage within 6 min after mixing,where the highest heat release rate was 6.29 J·g^(-1)·min^(-1),the maximum heat release was 205.3 J·g^(-1),and the main hydration product appeared at 50-60 min.The hydration behavior of SLMPC exhibits similarities to that of traditional MPC.Specifically,the acceleration phase is governed by an autocatalytic reaction,the deceleration phase is influenced by both autocatalytic reactions and diffusion processes,and the stabilization phase is predominantly controlled by diffusion mechanisms.This paper aims to establish the theoretical foundation for the industrial application of MS and the cost-effective production of MPC.展开更多
The wetting behavior of slag–coke is a crucial factor influencing the permeability of the lower part of the blast furnace.However,a systematic understanding of the wetting behavior and underlying mechanisms between t...The wetting behavior of slag–coke is a crucial factor influencing the permeability of the lower part of the blast furnace.However,a systematic understanding of the wetting behavior and underlying mechanisms between titanium-containing slag and tuyere coke remains lacking.The sessile drop method was employed to explore the effects of temperature,binary basicity,FeO,and TiO_(2) contents on the wetting behavior of titanium-containing slag and tuyere coke.The results indicate that increasing the temperature enhances the adhesion and wettability of the droplet,reducing the contact angle.Meanwhile,it accelerates the chemical reactions between slag and coke,leading to faster equilibrium.Conversely,increasing slag basicity elevates the contact angle by inhibiting chemical reactions at the slag–coke interface.This inhibition reduces both contact area and depth,thereby hindering slag droplet spreading on the coke surface.The contact angle decreases as the FeO content in the slag increases.Notably,the increase in TiO_(2) content has a dual effect on slag–coke wettability.Initially,it promotes wetting by reducing surface tension and lowering the contact angle.While the TiO_(2) content exceeds 20 wt.%,Ti(C,N)forms a barrier layer at the slag–coke interface,hindering the contact between slag and coke and resulting in an increased contact angle.展开更多
基金Supported by Carbon Neutrality and Energy System Transformation (CNEST) ProgramScience and Technology Innovation Project of CHN Energy (GJNY-24-26)。
文摘The service life of refractory brick in the slag tapping hole of gasifiers is a significant concern for long-term and stable operation.This study examined the damage mechanism of high chromia refractory of four commercial coal-water slurry gasifiers with their corresponding gasification coal samples and the corroded refractory bricks in the slag tapping hole of the gasifier.The slag characteristic,including crystallization and viscosity-temperature of four gasification coal samples were analyzed.The results revealed that the low viscosity slag could lead to more severe damage to refractory bricks.Given the risk of slag crystallization,it is recommended to establish a safe slag tapping temperature range should be set as tICT(initial crystallization temperature)−t_(2.5) when tICT is higher than t_(25).Upon examining interior morphology of these corroded refractory bricks,some cracks were observed within them.The chemical composition of molten slag was analyzed using SEM-EDS.However,XRD results found no spinel containing zirconium in these cracks.This suggests that the emergence of these cracks are mainly attributed to the molten slag penetration and the subsequent reaction with the refractory material.The difference in thermal expansion between the newly formed substances and refractory material is critical in forming these cracks.Furthermore,SEM-EDS analysis was also conducted on the slag-aggregate and the slag-matrix interface.The results reveal that the reduction in Cr_(2)O_(3) content is the earliest characteristic of damage in high chromia refractories.A proposed damage mechanism of refractory brick suggests that the matrix and aggregate of high chromia refractory are initially compromised because of the reduced Cr_(2)O_(3) content.Subsequently,the molten slag penetrates the interior of the refractory brick,forming new substances,leading to damage caused by the difference in thermal expansion between the new substances and the refractory brick.Understanding and preventing the reduction of Cr_(2)O_(3) content is vital to prolonging the service life of refractory brick in the slag tapping hole of the gasifier based on this damage mechanism.
基金support from the National Natural Science Foundation of China(Grant No.52174313)the Postgraduate Innovation Fundamental of Hebei Province(Grant No.CXZZBS2023126)the High Quality Steel Continuous Casting Engineering Technology Research Center at North China University of Science and Technology,Tangshan,China.
文摘In order to examine the flow state of the steel-slag interface in a thin slab mold at high casting speed,a flexible thin slab casting mold and a novel five-hole nozzle were investigated.The maximum velocity and fluctuation height of the steel-slag interface in the mold served as the evaluation criteria.Numerical simulation techniques,including large eddy simulation and volume of fluid,were employed to develop a two-phase flow model of liquid steel and slag.This model facilitated the analysis of the fluctuation behavior of the steel-slag interface and the mechanisms of slag entrapment.The results indicated that maintaining the stability of the steel-slag interface could be achieved by ensuring that the maximum velocity did not exceed 0.30 m s^(-1)or that the wave height remained below 30 mm.The relationship between the maximum velocity and wave height of the steel-slag interface was established by analyzing different casting speeds.Slag entrapment occurred when the maximum velocity exceeded the critical value.The critical velocity for shear slag entrapment was 0.485 m s^(-1),while for vortex slag entrapment,it was when the velocity of the swirl center reached 0.235 m s^(-1).Electromagnetic braking proved effective in controlling flow in the mold,reducing fluctuations in the steel-slag interface,preventing slag entrapment,and maintaining the position of the interface.Furthermore,it facilitated the control of the uniformity and stability of slag movement along the outer wall of the submerged entry nozzle and the copper wall of the mold.
基金Funded by the National Natural Science Foundation of China(No.51236003)the Natural Science Foundation of Gansu Province(No.1506RJZA076)。
文摘As the speeds of trains increase,higher demands are placed on brake materials.In order to overcome the thermal degradation phenomenon of brake pads during high-speed braking,we prepared copper fiber reinforced alkali-activated slag composite(AASC)friction materials by hot-pressing method,using slag as matrix,Na_(2)SiO_(3)·9H_(2)O as alkali excitant,copper fiber as reinforcement,and graphite as friction modifier.The results show that the AASC prepared by hot-pressing method has undergone alkali-activated reaction and has geopolymer amorphous characteristics as the conventional cast molding AASC by XRD analysis.The addition of copper fibers can improve the mechanical strength and toughness of the composites substantially,and the AASC has the highest flexural strength,compressive strength and impact toughness when the volume fraction of copper fibers reaches 25 vol%.Toughening mechanisms such as drawing,bridging and crack deflection of copper fibers in composites were analyzed by SEM morphology.Addition of appropriate amount of graphite to AASC can effectively reduce the wear rate and improve the stability of the material friction coefficient.The coefficient of friction also remains stable in the high-speed friction experiments without thermal degradation.Therefore,copper fiber reinforced AASC friction materials prepared by hot-pressing method has good mechanical and friction properties.
基金supported by Special Funding Projects for Local Science and Technology Development guided by the Central Committee(No.YDZJSX2022C028)the Fundamental Research Program of Shanxi Province(Nos.20210302123218 and 202203021211187)+4 种基金Innovation and Entrepreneurship Training Program for College Students in Shanxi Province(202210109006)the National Natural Science Foundation(52474367)the Key Research and Development for University-Local Government Collaboration of Lvliang City(2024XDHZ01)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2025Q022)the Foundation of State Key Laboratory of Advanced Metallurgy,USTB(K22-10).
文摘The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusions was characterized by the Kullback-Leibler(KL)divergence.The slag structure analysis revealed that the[AlO]tetrahedral structure was the primary network structure in the slag.With increasing the CaO content,the non-bridge oxygen(NBO)content in the slag structure increases,and the bridge oxygen(BO)content decreases,thereby reducing the complexity of the slag network structure.Raman spectroscopy detection verifies the results of the MD simulations.The results indicated that the dissolution rate of alumina inclusions accelerates with increasing the CaO content in the slag,owing to the reduced complexity of the slag network structure and the enhanced interatomic interactions.The simulation results for the dissolution of alumina inclusions were consistent with theoretical calculations based on the slag inclusion capacity and the dimensionless dissolution rate of inclusions.Radial distribution function analysis demonstrated that the interaction between atoms in the slag system and alumina inclusions strengthens,increasing the dissolution rate of alumina inclusions.The[AlO_(6)]octahedral structure of the alumina inclusions is disrupted,forming BO structures,which in turn enhances the complexity of the slag network structure,slowing the dissolution rate of alumina inclusions.In contrast,the slag system with a higher CaO content has a relatively simpler network structure,promoting faster alumina inclusion dissolution.
基金supported by the National Key Research and Development Program of China(No.2023YFB3712401),the National Natural Science Foundation of China(No.52274301)the Aeronautical Science Foundation of China(No.2023Z0530S6005)the Ningbo Yongjiang Talent-Introduction Programme(No.2022A-023-C).
文摘The viscosity of refining slags plays a critical role in metallurgical processes.However,obtaining accurate viscosity data remains challenging due to the complexities of high-temperature experiments,often relying on empirical models with limited predictive capabilities.This study focuses on the influence of optical basicity on viscosity in CaO-Al_(2)O_(3)-based refining slags,leveraging machine learning to address data scarcity and improve prediction accuracy.An automated framework for algorithm integration,parameter tuning,and evaluation ranking framework(Auto-APE)is employed to develop customized data-driven models for various slag systems,including CaO-Al_(2)O_(3)-SiO_(2),CaO-Al_(2)O_(3)-CaF_(2),CaO-Al_(2)O_(3)-SiO_(2)-MgO,and CaO-Al_(2)O_(3)-SiO_(2)-MgO-CaF_(2).By incorporating optical basicity as a key feature,the models achieve an average validation error of 8.0%to 15.1%,significantly outperforming traditional empirical models.Additionally,symbolic regression is introduced to rapidly construct domain-specific features,such as optical basicity-like descriptors,offering a potential breakthrough in performance prediction for small datasets.This work highlights the critical role of domain-specific knowledge in understanding and predicting viscosity,providing a robust machine learning-based approach for optimizing refining slag properties.
基金supported by the National Natural Science Foundation of China(No.52274318).
文摘A full-sectional microstructure characterization method was developed to investigate the formation of coarse slag rims during the continuous casting of hypo-peritectic steel.The cross-sectional microstructural analysis of typical slag rims for two highly crystalline powders revealed that their formation was primarily driven by the solidification of the liquid slag.Distinct differences were observed in the microstructures of slag rims from the two powders.Powder A(characterized by a higher breaking temperature and viscosity)displayed alternating lamellar microstructures of coarse and fine phases,with the coarse phases composed of akermanite-gehlenite transition phases.In contrast,powder B(with a lower breaking temperature and viscosity)predominantly comprised regular akermanite-gehlenite crystals interspersed with a certain amount of glassy phases.Numerical simulations of a three-phase fluid flow coupled with heat transfer indicate that slag rim formation correlates with mold oscillation.Solidification of the liquid slag at the slag rim front predominantly occurs during the negative stroke of the mold oscillation.The average heating rate during the ascending stage of the mold reaches approximately 100 K·s^(−1),whereas the average cooling rate during the descending stage attains 400 K·s^(−1).This temperature variation leads to the formation of lamellar microstructures,whereas the ascending stage promotes the formation of coarse structures and thicker slag rims.Based on the powder properties,two distinct formation pathways exist for highly crystalline mold powders.For the powders with a higher breaking temperature,higher viscosity,and narrower solidification range(powder A),coarse microstructures and thicker slag rims were preferentially formed.For powders with lower breaking temperature and viscosity and wider solidification ranges(powder B),the liquid slag resisted rapid solidification,and the extended mushy zone allowed the partial liquid slag to persist at the slag rim front,promoting the formation of a thin slag rim.This study enhances the understanding of slag rim formation in highly crystalline mold powders and provides critical insights into the control of longitudinal surface cracks in hypo-peritectic steel.
基金Funded by the Sichuan Province Science and Technology Support Program(No.2025YFNZH0022)the Chengdu Municipal Science and Technology Program(No.2025-YF11-00003-HZ)。
文摘Curing temperature significantly affects the pozzolanic reaction kinetics of phosphorous slag(PS),thereby governing the early-age(7 d)hydration behavior of PS composite binders at 20,30,and 60℃.The Krstulovic-Dabic kinetic model was applied to identify three characteristic processes:nucleation and growth(NG),phase boundary interaction(I),and diffusion(D).Control mixtures containing inert quartz powder with comparable particle size distributions were prepared for comparison.Pore characteristics of hardened PS pastes at different temperatures were analyzed via mercury intrusion porosimetry,while hydration products were characterized using X-ray diffraction(XRD)and thermogravimetric analysis(TG-DTG).The experimental results indicate that the retarding effect of PS on early cement hydration outweighs its accelerating effect,attributed to the combined influence of nucleation and dilution,with retardation decreasing as temperature increases.PS exhibits early reactivity and continuously consumes calcium hydroxide through the pozzolanic reaction,as evidenced by stable phase assemblages accompanied by reduced CH content in XRD and TG-DTG analyses.At 20℃,increasing PS content maintains the NG→I→D mechanism but slows reaction rates across all stages.Elevated temperatures significantly accelerate the NG process,shifting the dominant mechanism from NG toward D.Simultaneously,enhanced PS reactivity contributes to a refined pore structure and improved compressive strength.
基金supported by National Natural Science Foundation of China(Nos.52204309,52174277 and 52374300)Fundamental Funds for the Central Universities(No.N2425026)。
文摘Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates with varying manganese concentrations(VL-cMn)were prepared through calcium,a calcium-manganese composite,and manganese-based roasting of vanadium slag(VS)to investigate the influence of manganese on vanadium precipitation behavior during hydrolysis precipitation(HP)and ammonium salt precipitation(AP),as well as the microscopic characteristics and purity of the resulting V_(2)O_(5) products.The results showed that increasing the pH mitigated the negative effects of Mn on the V precipitation rate during HP.However,as the manganese concentration increased from 5.69 to 15.38 g/L,the V precipitation rate gradually declined at higher temperatures and longer reaction times.The precipitates exhibited increased microstructural density,which might had contributed to the formation of Mn-bearing phases.Additionally,the average grain size of V_(2)O_(5) was reduced and the particles were increasingly agglomerated,leading to a 2.55%decrease in product purity.For AP,as manganese concentration increased,raising the pH counteracted the negative impact of Mn on the V precipitation rate and reduced the required amount of ammonium sulfate.Moreover,Mn was unevenly adsorbed on the surface of the precipitates.Although V_(2)O_(5) grains gradually shrank and became denser,there was no significant effect on the final product purity,which remained above 99.3%.In conclusion,roasting with added manganese salts influenced the hydrolysis of vanadium but had no significant effect on acidic ammonium salt precipitation.
基金supported by the Science and Technology Research Partnership for Sustainable Development(SATREPS)。
文摘The iron and steel industries generate large amounts of unavoidable CO_(2)emissions as well as considerable quantities of slags.More than one-half of the emitted CO_(2)is produced in blast furnaces during ironmaking,and thus it is meaningful to use blast furnace slags to capture CO_(2)while addressing the byproducts and flue gas of ironmaking.Mineral carbonation of slags is a promising route to achieve carbon neutrality and effective slag utilization.To exploit slag more effectively and capture CO_(2)in flue gas,an in-depth investigation into the carbonation of blast furnace slags generated with different cooling methods was conducted.The effects of the solid–liquid ratio and introduced CO_(2)concentration on carbonation were determined.The CO_(2)uptake capacity of air-cooled slag(0.04 g/g)was greater than that of water-quenched slag.The CO_(2)uptake capacities of the two slags were comparable with those of slags in previous works,indicating the potential of the two slags for CO_(2)sequestration and utilization even with low-energy input and this fact suggests that this process is feasible.
基金supported by the following funds:Guizhou Science and Technology Support Program Project[Grant No.Guizhou Science and Technology Cooperation Support(2025)General 079]Guizhou Provincial Department of Education’s"Top 100 Schools and Thousand Enterprises in Science andTechnology Research and Development"Project in 2025(Contract Number:Guizhou Education and Technology[2025]No.009)+6 种基金Hebei Province Innovation Ability Improvement Plan(No.23561001D)Hebei Provincial Natural Science Foundation(No.H2022209089)Open Fund Project of the Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(Grant No.FMRUlab23-03)the National Natural Science Foundation of China(No.52074128)Basic Scientific Research Business Expenses of Colleges and Universities in Hebei Province(Nos.JYG2022001 and JQN2023008)Tangshan Talent Funding Project(No.A202202007),Natural Science Foundation of Hebei Province(No.E2023209107)Foundation of Tangshan Science and Technology Bureau(No.23150219A).
文摘Metallurgical slag is a waste or by-product of the metallurgical process,and its improper disposal can pose negative environmental impacts,including groundwater and soil contamination.The composition and properties of metallurgical slag are complex,which is usually difficult to use or process directly and requires special treatment and utilization methods.Taking converter slag and blast furnace slag as examples,the research frontiers and development potential were primarily discussed and analyzed in three aspects:the recycling within and outside metallurgical slag plants,the extraction and utilization of thermal energy from metallurgical slag,and the functionalization and social application of metallurgical slag.The metallurgical slag waste heat recovery includes chemical methods and physical methods.Among them,the physical method currently most used was centrifugal granulation to recover heat.Chemical laws could recover hydrogen through the waste heat of metallurgical slag,which could save fuel and reduce CO_(2) generated by fuel combustion.Metallurgical slag is rich in alkaline metal oxides,which can undergo a carbonation reaction with CO_(2) to achieve carbon sequestration in metallurgical slag.Elements such as iron,phosphorus,and silicon contained in metallurgical slag could be used in soil conditioners,cement raw materials,and wastewater treatment.For example,the phosphorus element in the slag could be extracted by melt modification followed by acid leaching and used as a raw material for phosphate fertilizer.Therefore,under the background of China’s carbon neutrality goal,it is important to develop the key technologies of waste heat utilization of metallurgical slag and carbon sequestration of metallurgical slag.
文摘High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase compositions were measured by electron probe microanalysis(EPMA).A series of pseudo-ternary and pseudo-binary phase diagrams are constructed to demonstrate their applications in copper smelting process and evaluation of the thermodynamic database.Spinel and tridymite are identified to be the major primary phases in the composition range related to the copper smelting slags.It is found that the operating window of the smelting slag is primarily determined by w_(Fe)/w_(SiO_(2))ratio in the slag.Both MgO and Al_(2)O_(3)in the slag reduce the operating window which requires extra fluxing agent to keep the slag to be fully liquid.Complex spinel solid solutions cause inaccurate predictions of the current thermodynamic database.
基金Supported by Key Research and Development Program Project of Hubei Province(No.2023DJC157)。
文摘Low-carbon alkali-activated slag(AAS)is among the most common alkali-activated materials(AAMs).To further lower CO_(2) emissions and optimize the material system,we proposed a scheme of using phosphorous slag(PS)to substitute ground granulated blast-furnace slag(GGBS)in sodium carbonate(NC)activated slag system.we conducted a systematic study on the mechanical properties of the NC-activated slag/PS blends at normal temperature and examined the influences of different substitution amounts of phosphorus slag and NC equivalents on the performance of the material system.The hydration process was analyzed using hydration flow and chemical shrinkage.The hydration products were characterized via XRD and TGA.Moreover,the pore structure and pH value were also analyzed.When the substitution dosage of PS was not greater than 30%,the 3 d compressive strength of the systems was improved to a certain degree.However,in the medium and later periods,the compressive strength of the systems was slightly lower than that of the control group.The 90 d compressive strength of the control group 4SC-0% was 47.6 MPa,which was 4.0 MPa lower than the 28 d one of itself,presenting a strength retrogression phenomenon,while all the test groups demonstrated a continuous growth law.When the substitution dosage of PS was not more than 30%,the hydration reaction of the AAS system was facilitated,whereas when the substitution amount was 50%,the hydration of the system was conspicuously slowed down.The incorporation of phosphorous slag was capable of enhancing the volume stability of the material system.The hydration products of this system were likely to be manasseite,calcite,and C-S-(A)-H.When the incorporation amount of phosphorous slag increased,the quantity of the hydration products reduced,which might result in the generation of C-N-S-A-H.The study proposed the methodology for designing weak base-activated slag/PS.
基金China Postdoctoral Science Foundation (No. 2020M682337)。
文摘In the Pidgeon process involving a vertical pot,bonded slag pellets occasionally emerge at the bottom of the reduction pot,impeding smooth slag discharge.To reveal the formation mechanism of the bonded slag pellets,thermodynamic calculations,X-ray diffraction(XRD),X-ray fluorescence spectrometry(XRF),electron probe microanalyzer(EPMA),X-ray photoelectron spectroscopy(XPS),and differential scanning calorimetry(DSC)were employed.The bonded slag pellets mainly comprise MgO,CaSi_(2),CaO,and Ca2SiO_(4).CaSi_(2) in the bonded slag pellets is attributed to the reduction reaction between Si and CaO,yielding liquid CaSi_(2).Simultaneously,the reaction between CaSi_(2) and MgO,which will typically produce Mg vapor,is inhibited,resulting in the accumulation of CaSi_(2).Owing to the solid-liquid transition of CaSi_(2),this process culminates in the bonding of slag pellets.This study can guide the Pidgeon process optimization,enabling mitigation of the“dead pot”issue,thereby enhancing efficiency and reducing costs.
基金supported by the National Key Research and Development Program of China(No.2022YFC3901405)the Excellent Youth Project of Anhui Provincial Natural Science Foundation(No.2408085Y030)Overseas Study Funding Program for Young Faculty of Anhui Province(2023-11).
文摘Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-temperature nickel-iron blast furnace molten slag(NBFS)was investigated.The results show that the flow temperature of the slag decreases with the increase in the proportion of SSPS.In a certain range,the flow temperature decreases by about 7℃ when the proportion of SSPS increases by 1%.The computational results from FactSage indicate that the addition of SSPS leads to a reduction in MgO content and an increase in CaO and CaSO_(4) contents,which are the reasons for the decrease in the flow temperature.Mortar blocks were prepared by mixing the slag powder prepared by water-quenched slag drying ball milling with 425 Portland cement in a certain proportion.As the proportion of SSPS increased from 0 to 5%,the 7-day strength of mortar blocks increased from 22.32 to 26.98 MPa,and the 28-day strength increased from 37.28 to 41.43 MPa.The 28-day activity index is above 75%,and its activity index meets the requirements of S75 ground granulated blast furnace slag.The industrial application program in the nickel-iron blast furnace with a volume of 550 m^(3) was also put forward,which provides a new way for realizing the resource utilization of SSPS.
基金supported by the National Key Research and Development Program(Nos.2023YFC3707101 and 2023YFF0614301)the Tsinghua University Initiative Scientific Research Program(No.2023Z02JMP001)the Linghang Project of School of Environment(No.025108011).
文摘Carbon dioxide (CO_(2)) mineralization technology has attracted significant attention, due tothe synergistic terminal treatment of CO_(2) and industrial waste. The combined CO_(2) mineralizationprocess with steel enterprises is a promising route to simultaneously address CO_(2)emissions and SS treatment. Recently, a serial of the relevant work focus on a single type ofsteel slag (SS), and the understanding of CO_(2) absorption by mineralization of various SS isvery lacking.Meanwhile, it is urgent requirement for systematic summary and discussion onhow to make full use of the mineralized products produced after the mineralization of CO_(2)in SS. This review aims to investigate the progress of CO_(2) mineralization using SS, includingthe potential applications of mineralization products, as well as the environmental impactand risk assessment ofmineralization product applications. Currently, the application of SSmineralization products is primarily focused on their use as construction materials with loweconomic value. With usage of the mineralization products for ecological restoration (e.g.sandy soil remediation) was treated as an advanced route, but still remaining challenge infunctional materials preparation, and its technical economy and possible hazards need tobe further explored by long-term experimental tests.
基金funded by the National Natural Science Foundation of China(No.52308316)Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province(No.ZJRMG-2022-01)+1 种基金Fudamental Research Funds for the CentralUniversities,CHD(No.300102265303)the Science and Technology Innovation Project of China Coal Technology&Engineering Group Shenyang Engineering Company(No.NKJ001-2025).
文摘In the steel slag-based mine backfill cementitious material systems,the hydration reaction mechanisms and synergistic effects of steel slag(SS),granulated blast furnace slag(GBFS),and desulfurization gypsum(DG)are crucial for performance optimization and regulation.However,existing studies have yet to fully reveal the underlying synergistic mechanisms,which limits the application and promotion of high SS content in mine backfill and low-carbon building materials.This study systematically explores the synergistic effects between various solid wastes and their regulation of the hydration process in the SS-based cementitious system through multi-scale characterization techniques.The results show that GBFS,by releasing active Si^(4+)and Al^(3+),triggers a synergistic activation effect with Ca^(2+)provided by SS,promoting the formation of C-S-H gel and ettringite,significantly optimizing the hardened paste microstructure.When the GBFS content reaches 30%,the C-S-H content increases by 40.8%,the pore size distribution improves,the proportion of large pores decreases by 68.7%,and the 90-day compressive strength increases to 5 times that of the baseline group.The sulfate activation effect of DG accelerates the hydration of silicate minerals,but excessive incorporation(>16%)can lead to microcracks caused by the expansion of AFt crystals,resulting in a strength reduction.Under the synergistic effect of 8%DG and 30%GBFS,the hydration reaction is most intense,with the peak heat release rate reaching 0.92 mW/g and the cumulative heat release amount being 240 J/g.By constructing a“SS-GBFS-DG-cement”quaternary synergistic system(mass ratio range:SS:GBFS:cement:DG=(50–62):(20–40):10:(8–12)),the matching of active components in high-content SS systems was optimized,significantly improving microstructural defects and meeting engineering application requirements.This study provides a theoretical basis for the component design and performance regulation of high-content SS-based cementitious materials.
基金supported by the National Natural Science Foundation of China(Nos.52074050,52222407)。
文摘China is the world’s largest producer of vanadium products,whose major vanadium resource is vanadium slag obtained by smelting vanadium−titanium magnetite ores.The vanadium extraction techniques from vanadium slag have progressed stepwise toward greenization during the past 30 years in China.This review has systematically summarized these developments and classified the developments into three stages.The early stage is the efficient vanadium extraction techniques such as the sodium roasting−water leaching technique.The developed stage is the clean vanadium extraction techniques including the calcification roasting−acid leaching technique and sub-molten salt technique.The advanced stage is the green vanadium extraction techniques,for example the magnesiation roasting−acid leaching technique.The mechanisms,advantages and disadvantages of industrially applied and literature reported vanadium extraction techniques in each development stage are elaborated from multiple perspectives.Finally,future development directions are pointed out,aiming to inspire green extraction technique of vanadium worldwide.
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.
基金financially supported by the Natural Science and Engineering Technology in Qinghai Province(2023)the Qinghai Province"Kunlun Talents"High end Innovation and Entrepreneurship Talent Project(2023)+4 种基金the Western Young Scholars Program of Chinese Academy of Sciences(20242022000018)the National Natural Science Foundation of China(52404189)the Open Fund of Key Laboratory of Green and High-end Utilization of Salt Lake Resources(ISL2024-15)the Independent deployment project of the Qinghai Salt Lake Research Institute,CAS(E455HX3501)。
文摘Magnesium phosphate cements(MPC)have shown promising applications in many fields,but high raw material prices hinder their development.The production of salt lake MPC(SLMPC)from magnesium slag(MS),a byproduct of lithium extraction from salt lakes,offers significant environmental and economic advantages.In this study,a low-cost magnesia raw material was obtained through the calcination of MS,which was subsequently utilized in conjunction with KH_(2)PO_(4) to prepare SLMPC.The changes in hydration products,microscopic morphology,solution pH value,and TG content during the SLMPC curing process,and the hydration kinetics equation and model were used to study the hydration processes of SLMPC.The results show that the outcome indicates that the SLMPC system entered the accelerated reaction stage within 6 min after mixing,where the highest heat release rate was 6.29 J·g^(-1)·min^(-1),the maximum heat release was 205.3 J·g^(-1),and the main hydration product appeared at 50-60 min.The hydration behavior of SLMPC exhibits similarities to that of traditional MPC.Specifically,the acceleration phase is governed by an autocatalytic reaction,the deceleration phase is influenced by both autocatalytic reactions and diffusion processes,and the stabilization phase is predominantly controlled by diffusion mechanisms.This paper aims to establish the theoretical foundation for the industrial application of MS and the cost-effective production of MPC.
基金supported by the Postdoctor Project of Hubei Province(2024HBBHCXA074)National Natural Science Foundation of China(51974212)+2 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(BWLCF202116)Foundation of Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking(NPISlab25-03)Science and Technology Major Project of Wuhan(2023020302020572).
文摘The wetting behavior of slag–coke is a crucial factor influencing the permeability of the lower part of the blast furnace.However,a systematic understanding of the wetting behavior and underlying mechanisms between titanium-containing slag and tuyere coke remains lacking.The sessile drop method was employed to explore the effects of temperature,binary basicity,FeO,and TiO_(2) contents on the wetting behavior of titanium-containing slag and tuyere coke.The results indicate that increasing the temperature enhances the adhesion and wettability of the droplet,reducing the contact angle.Meanwhile,it accelerates the chemical reactions between slag and coke,leading to faster equilibrium.Conversely,increasing slag basicity elevates the contact angle by inhibiting chemical reactions at the slag–coke interface.This inhibition reduces both contact area and depth,thereby hindering slag droplet spreading on the coke surface.The contact angle decreases as the FeO content in the slag increases.Notably,the increase in TiO_(2) content has a dual effect on slag–coke wettability.Initially,it promotes wetting by reducing surface tension and lowering the contact angle.While the TiO_(2) content exceeds 20 wt.%,Ti(C,N)forms a barrier layer at the slag–coke interface,hindering the contact between slag and coke and resulting in an increased contact angle.
