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
The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-ri...The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-rich components of CGFS(CGFS-H)and systematically investigates the selective leaching behavior of Fe^(3+),Al^(3+)and Ca^(2+)using three organic acid extractants,i.e.,citric acid,tartaric acid,and tetrasodium iminodisuccinate.Additionally,the stepwise leaching of iron,aluminum and calcium from CGFS-H is explored.The selective dissolution mechanisms of these metals by different organic acids are elucidated through X-ray diffraction(XRD),X-ray fluorescence(XRF),and scanning electron microscopy(SEM)analyses.The results indicate that tetrasodium iminodisuccinate exhibits the highest leaching selectivity for Fe^(3+),while tartaric acid demonstrateds a comparable affinity for both Fe^(3+)and Al^(3+).In contrast citric acid shows superior selectivity toward Ca^(2+).The leaching yield of Fe^(3+),Al^(3+)and Ca^(2+)after sequential leaching with the three organic acids were 79.8%,65.08%and 78.6%,respectively.These findings confirm that effective and selective separation of Fe^(3+),Al^(3+)and Ca^(2+)from CGFS-H can be achieved via optimized organic acid-based leaching strategies.This advancement provides a critical foundation for developing Ca/Fe/Al hydrotalcite materials using CGFS-H as a sustainable feedstock,thereby facilitating the transformation of waste residue into high-value functional materials and promoting resourceefficient utilization of coal gasification fine slag.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
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
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
Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcemen...Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcement corrosion.To address these limitations,this study proposes an improved design framework for low-carbon slag concrete that simultaneously incorporates carbonation durability and cover scaling effects into the mix proportioning process.Based on experimental data,a linear predictive model was developed to estimate the 28-day compressive strength of slag concrete,achieving a correlation coefficient of R=0.87711 and a root mean square error(RMSE)of 7.55 MPa.The mechanism-based equation exhibits strong physical interpretability,as each parameter corresponds to a clear physical process,satisfying the requirements of design codes for physical significance.By integrating the strength and carbon-emission models,the carbon-emission efficiency was further analyzed.Across all water–binder ratios(0.3,0.4,0.5),CO_(2) emissions per unit strength decreased steadily with increasing slag content,indicating that carbon efficiency is primarily governed by slag replacement rather than the water/binder ratio.Four design cases,all with a design strength of 30 MPa,were then evaluated to illustrate the combined effects of carbonation and scaling.In Case 1,without considering carbonation durability,the carbonation depth after 50 years exceeded the 25 mm cover,leading to potential corrosion.In Case 2,when carbonation durability was considered,the required actual strength increased to 31.28 MPa.When mild cover scaling of 3 mm was introduced(Case 3),the required strength rose to 34.59 MPa,and under severe scaling of 10 mm(Case 4),it increased to 45.73 MPa.These results indicate that intensified scaling demands higher strength and lower water/binder ratios to maintain durability.Overall,the proposed framework quantitatively balances strength,durability,and embodied carbon,supporting sustainable low-carbon concrete design.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
Acid is commonly used to separate phosphorus-containing solid solutions from steelmaking slag.However,the acid leaching solution obtained from this process cannot be directly utilized and thus requires purification.Th...Acid is commonly used to separate phosphorus-containing solid solutions from steelmaking slag.However,the acid leaching solution obtained from this process cannot be directly utilized and thus requires purification.The effect of different conditions on the calcium and iron removal characteristics of modified steelmaking slag leaching solution was investigated.Additionally,the removal mechanism was analyzed by thermodynamic calculations.The results indicated that the addition of soybean straw ash in steelmaking slag modification enabled K_(2)O to enter the phosphorus-containing solid solution,promoting phosphorus enrichment.Valuable elements such as phosphorus and potassium were more easily dissolved in the mixed acid.The oxalic acid concentration had a significant effect on the calcium removal rate,whereas the effects of temperature,stirring rate,and time on the calcium removal rate were minor.The main component of the calcium removal precipitate was CaC_(2)O_(4)·H_(2)O,with a removal rate up to 94.48%.During the iron removal process,when the pH value of the solution was low,Fe^(3+)mainly reacted to form the iron hydroxide precipitate for removal.Increasing the pH value of the solution would cause Fe^(3+)to combine with H_(2)PO_(4)^(-),forming FePO_(4)·2H_(2)O precipitate,leading to a reduction in the phosphorus content of the leaching solution.展开更多
Leakage of electrolytic manganese slag(EMS)ponds is a long-lasting and serious threat to environmental health worldwide,particularly in karst areas where the ecosystems are highly sensitive to geochemical perturbation...Leakage of electrolytic manganese slag(EMS)ponds is a long-lasting and serious threat to environmental health worldwide,particularly in karst areas where the ecosystems are highly sensitive to geochemical perturbations.However,the mechanisms of Mn mobilization and migration are insufficiently known.In this study,we combine systematic field investigations,laboratory column experiments and geochemical analyses to clarify the environmental geochemistry and controlling factors of leaching of Mn in the karst areas of southwestern China.While the Mn slag ponds as a whole had shown a low permeability,release of free Mn^(2+)and NH_(3)-N is significantly facilitated by the synergies of seepage infiltration,microbial activities and environmental acidification.With the increase of depth,the mineralogical composition of the slag undergoes significant alteration,and redox conditions change from acidic-oxidizing to acidic-reducing environments,which will accelerate the mobilization of Mn further and increase the risk of groundwater contamination.In addition,the presence of clay mineral colloids in Mn slag changes the migration properties of Mn,which introduces complexity in the geochemical behavior of Mn.Our findings highlight that Mn transformation and migration are controlled by dynamic,depth-dependent geochemical processes and the interplay of both internal and external factors.This research consolidates mechanistic foundation of deciphering Mn environmental behaviors in karst regions,reinforcing the urgency of preventing and rehabilitating electrolytic Mn slag leakage.展开更多
Recovering LiFePO_(4) extraction slag(LES)-the FePO_(4)-rich residue formed after Li leaching from spent LiFePO_(4)-has become pivotal to minimizing resource losses,mitigating environmental risks,and advancing circula...Recovering LiFePO_(4) extraction slag(LES)-the FePO_(4)-rich residue formed after Li leaching from spent LiFePO_(4)-has become pivotal to minimizing resource losses,mitigating environmental risks,and advancing circularity in lithium-ion battery value chains.However,integrative frameworks that link closed-loop routes(returning to battery precursors/cathodes)with non-closed-loop upcycling are still limited,constraining process optimization and scale-up.This review synthesizes current progress in LES recycling with emphasis on maximizing recovery efficiency and product value.In closed-loop pathways,hydrometallurgical purification removes impurities to yield battery-grade FePO_(4) as an LiFePO_(4) precursor,while direct relithiation(e.g.,solid-state sintering aided by Li sources and reductants)restores Li and reduces Fe^(3+)to Fe^(2+),thereby regenerating LiFePO_(4) cathodes from LES.In non-closed-loop pathways,compositionally guided upcycling converts LES into advanced materials(e.g.,high-performance electrodes,highcapacity adsorbents),thereby broadening the techno-economic value propositions.We also distill lessons from early industrial practice,identifying constraints arising from feedstock variability,energy-cost coupling(thermal/chemical utilities),and product-quality assurance(battery-grade specifications).Finally,we map research directions-including data-driven feed characterization and process control,defecthealing relithiation strategies and interfacial engineering,quality grading and market pathways,and multi-scenario deployment-to enhance the technical and economic sustainability of LES recycling and accelerate its contribution to a circular battery economy.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
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
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
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
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
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
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
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Supported by National Natural Science Foundation(52374279)。
文摘The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-rich components of CGFS(CGFS-H)and systematically investigates the selective leaching behavior of Fe^(3+),Al^(3+)and Ca^(2+)using three organic acid extractants,i.e.,citric acid,tartaric acid,and tetrasodium iminodisuccinate.Additionally,the stepwise leaching of iron,aluminum and calcium from CGFS-H is explored.The selective dissolution mechanisms of these metals by different organic acids are elucidated through X-ray diffraction(XRD),X-ray fluorescence(XRF),and scanning electron microscopy(SEM)analyses.The results indicate that tetrasodium iminodisuccinate exhibits the highest leaching selectivity for Fe^(3+),while tartaric acid demonstrateds a comparable affinity for both Fe^(3+)and Al^(3+).In contrast citric acid shows superior selectivity toward Ca^(2+).The leaching yield of Fe^(3+),Al^(3+)and Ca^(2+)after sequential leaching with the three organic acids were 79.8%,65.08%and 78.6%,respectively.These findings confirm that effective and selective separation of Fe^(3+),Al^(3+)and Ca^(2+)from CGFS-H can be achieved via optimized organic acid-based leaching strategies.This advancement provides a critical foundation for developing Ca/Fe/Al hydrotalcite materials using CGFS-H as a sustainable feedstock,thereby facilitating the transformation of waste residue into high-value functional materials and promoting resourceefficient utilization of coal gasification fine slag.
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 the National Natural Science Foundation of China(No.52463034)supported by the Korea Institute of Energy Technology Evaluation and Planning funded by the Ministry of Trade,Industry and Energy(No.2025-02314098)of the Republic of Koreasupported by the Regional Innovation System&Education(RISE)program through the Gangwon RISE Center,funded by the Ministry of Education(MOE)and the Gangwon State(G.S.),Republic of Korea(2025-RISE-10-002).
文摘Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcement corrosion.To address these limitations,this study proposes an improved design framework for low-carbon slag concrete that simultaneously incorporates carbonation durability and cover scaling effects into the mix proportioning process.Based on experimental data,a linear predictive model was developed to estimate the 28-day compressive strength of slag concrete,achieving a correlation coefficient of R=0.87711 and a root mean square error(RMSE)of 7.55 MPa.The mechanism-based equation exhibits strong physical interpretability,as each parameter corresponds to a clear physical process,satisfying the requirements of design codes for physical significance.By integrating the strength and carbon-emission models,the carbon-emission efficiency was further analyzed.Across all water–binder ratios(0.3,0.4,0.5),CO_(2) emissions per unit strength decreased steadily with increasing slag content,indicating that carbon efficiency is primarily governed by slag replacement rather than the water/binder ratio.Four design cases,all with a design strength of 30 MPa,were then evaluated to illustrate the combined effects of carbonation and scaling.In Case 1,without considering carbonation durability,the carbonation depth after 50 years exceeded the 25 mm cover,leading to potential corrosion.In Case 2,when carbonation durability was considered,the required actual strength increased to 31.28 MPa.When mild cover scaling of 3 mm was introduced(Case 3),the required strength rose to 34.59 MPa,and under severe scaling of 10 mm(Case 4),it increased to 45.73 MPa.These results indicate that intensified scaling demands higher strength and lower water/binder ratios to maintain durability.Overall,the proposed framework quantitatively balances strength,durability,and embodied carbon,supporting sustainable low-carbon concrete design.
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 Natural Science Foundation of China(52074004 and 51604003)Anhui Provincial Natural Science Foundation(2508085Y032).
文摘Acid is commonly used to separate phosphorus-containing solid solutions from steelmaking slag.However,the acid leaching solution obtained from this process cannot be directly utilized and thus requires purification.The effect of different conditions on the calcium and iron removal characteristics of modified steelmaking slag leaching solution was investigated.Additionally,the removal mechanism was analyzed by thermodynamic calculations.The results indicated that the addition of soybean straw ash in steelmaking slag modification enabled K_(2)O to enter the phosphorus-containing solid solution,promoting phosphorus enrichment.Valuable elements such as phosphorus and potassium were more easily dissolved in the mixed acid.The oxalic acid concentration had a significant effect on the calcium removal rate,whereas the effects of temperature,stirring rate,and time on the calcium removal rate were minor.The main component of the calcium removal precipitate was CaC_(2)O_(4)·H_(2)O,with a removal rate up to 94.48%.During the iron removal process,when the pH value of the solution was low,Fe^(3+)mainly reacted to form the iron hydroxide precipitate for removal.Increasing the pH value of the solution would cause Fe^(3+)to combine with H_(2)PO_(4)^(-),forming FePO_(4)·2H_(2)O precipitate,leading to a reduction in the phosphorus content of the leaching solution.
基金financially supported by the National Natural Science Foundation of China(No.42077184)Guizhou Institute of Technology's Research Initiation Fund Project for High-Level Talents(No.XJGC20190602)。
文摘Leakage of electrolytic manganese slag(EMS)ponds is a long-lasting and serious threat to environmental health worldwide,particularly in karst areas where the ecosystems are highly sensitive to geochemical perturbations.However,the mechanisms of Mn mobilization and migration are insufficiently known.In this study,we combine systematic field investigations,laboratory column experiments and geochemical analyses to clarify the environmental geochemistry and controlling factors of leaching of Mn in the karst areas of southwestern China.While the Mn slag ponds as a whole had shown a low permeability,release of free Mn^(2+)and NH_(3)-N is significantly facilitated by the synergies of seepage infiltration,microbial activities and environmental acidification.With the increase of depth,the mineralogical composition of the slag undergoes significant alteration,and redox conditions change from acidic-oxidizing to acidic-reducing environments,which will accelerate the mobilization of Mn further and increase the risk of groundwater contamination.In addition,the presence of clay mineral colloids in Mn slag changes the migration properties of Mn,which introduces complexity in the geochemical behavior of Mn.Our findings highlight that Mn transformation and migration are controlled by dynamic,depth-dependent geochemical processes and the interplay of both internal and external factors.This research consolidates mechanistic foundation of deciphering Mn environmental behaviors in karst regions,reinforcing the urgency of preventing and rehabilitating electrolytic Mn slag leakage.
基金financially supported by the National Key Research and Development Program of China(Nos.2023YFC3904800)the National Outstanding Young Scientists Fund(No.52125002)+6 种基金the National Science Foundation of China(No.22476073 and U24A20194)the Key Project of Jiangxi Provincial Research and Development Program(Nos.20223BBG74006and 20243BBI91001)the Jiangsu Special Fund on Technology Innovation of Carbon Dioxide Peaking and Carbon Neutrality(No.BT2024011)the China Postdoctoral Science Foundation(Nos.2024M751282 and 2025T180353)the“Thousand Talents Program”of Jiangxi Province(S2021GDQN2161)the Key Project of Ganzhou City Research and Development Program(No.2023PGX17350)the Key Laboratory of Jiangxi Province for Functional Biology and Pollution Control in Red Soil Regions(No.2023SSY02051)。
文摘Recovering LiFePO_(4) extraction slag(LES)-the FePO_(4)-rich residue formed after Li leaching from spent LiFePO_(4)-has become pivotal to minimizing resource losses,mitigating environmental risks,and advancing circularity in lithium-ion battery value chains.However,integrative frameworks that link closed-loop routes(returning to battery precursors/cathodes)with non-closed-loop upcycling are still limited,constraining process optimization and scale-up.This review synthesizes current progress in LES recycling with emphasis on maximizing recovery efficiency and product value.In closed-loop pathways,hydrometallurgical purification removes impurities to yield battery-grade FePO_(4) as an LiFePO_(4) precursor,while direct relithiation(e.g.,solid-state sintering aided by Li sources and reductants)restores Li and reduces Fe^(3+)to Fe^(2+),thereby regenerating LiFePO_(4) cathodes from LES.In non-closed-loop pathways,compositionally guided upcycling converts LES into advanced materials(e.g.,high-performance electrodes,highcapacity adsorbents),thereby broadening the techno-economic value propositions.We also distill lessons from early industrial practice,identifying constraints arising from feedstock variability,energy-cost coupling(thermal/chemical utilities),and product-quality assurance(battery-grade specifications).Finally,we map research directions-including data-driven feed characterization and process control,defecthealing relithiation strategies and interfacial engineering,quality grading and market pathways,and multi-scenario deployment-to enhance the technical and economic sustainability of LES recycling and accelerate its contribution to a circular battery economy.
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 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.
