The slagging/fouling due to the accession of fireside deposits on the steam boilers decreases boiler efficiency and availability which leads to unexpected shut-downs. Since it is inevitably associated with the three m...The slagging/fouling due to the accession of fireside deposits on the steam boilers decreases boiler efficiency and availability which leads to unexpected shut-downs. Since it is inevitably associated with the three major factors namely the fuel characteristics, boiler operating conditions and ash behavior, this serious slagging/fouling may be reduced by varying the above three factors. The research develops a generic slagging/fouling prediction tool based on hybrid fuzzy clustering and Artificial Neural Networks (FCANN). The FCANN model presents a good accuracy of 99.85% which makes this model fast in response and easy to be updated with lesser time when compared to single ANN. The comparison between predictions and observations is found to be satisfactory with less input parameters. This should be capable of giving relatively quick responses while being easily implemented for various furnace types.展开更多
A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vana...A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.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
Slag viscosity plays a crucial role in the smelting process.A slag viscosity prediction model was developed by integrating hyperparameter optimization algorithms,machine learning,and SHapley Additive exPlanations(SHAP...Slag viscosity plays a crucial role in the smelting process.A slag viscosity prediction model was developed by integrating hyperparameter optimization algorithms,machine learning,and SHapley Additive exPlanations(SHAP)analysis.The developed slag viscosity prediction models were evaluated using multiple statistical metrics,leading to the identification of the optimal model—Bayesian optimization-based categorical boosting(BO-CatBoost).And this model was further compared with existing models,including NPL model,FactSage+Roscoe-Einstein(RE)equation,artificial neural network model+RE equation,Riboud model+RE equation,and Zhang model.The results indicate that the slag viscosity prediction model based on BO-CatBoost outperforms all other models,achieving a coefficient of determination of 0.9897,a root mean square error of 1.0619,a mean absolute error of 0.6133,and a hit ratio of 95.1%.The global interpretability analysis of SHAP analysis was used to reveal the importance degree of different features on slag viscosity.The local interpretability analysis of SHAP analysis was used to obtain the quantitative influence of different features on slag viscosity in specific samples.The high-accuracy and interpretable slag viscosity prediction model developed is beneficial to the intelligent design of slag composition.展开更多
This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag visc...This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag viscosity,Raman spectroscopy,and molecular dynamics.The Raman spectroscopy results indicate that an increase in TiO_(2) content leads to the gradual depolymerization of complex Q_(Si)^(3) Q_(Si)^(2) Q_(Si)^(0) Q_(Si)^(1)silicate structures(and)into simpler structures(and)in the slag.At the same time,the Al-O-Al bonds in the aluminate structures of the slag also depolymerize into simpler Al-O-forms,resulting in a decrease in the degree of polymerization of both silicates and aluminates.In contrast,an increase in Al_(2)O_(3) content generally results in an increased degree of polymerization for the silicates and aluminates.Molecular dynamics simulations of the polymerization and depolymerization processes in the microstructure of the blast fur-nace slag reveal that Si and Al mainly exist in tetrahedral[SiO_(4)]^(4-)and[AlO_(4)]^(4-),while Ti mainly exists in the form of simple pentaco-ordinate[TiO_(5)]^(6-)and hexacoordinate[TiO_(6)]^(8-).TiO_(2) exhibits basic properties in this system,whereas Al_(2)O_(3) demonstrates acidic behavior.The addition of TiO_(2) introduces free oxide ions into the system,causing the bridging oxygens to break into non-bridging oxygens,lead-Q_(Si)^(4) Q_(Si)^(3)ing to the depolymerization of complex structures and,which simplifies the slag structure.On the other hand,an increase in Al_(2)O_(3) content tends to capture or share the oxide ions within the system to form[AlO_(4)]^(4-),resulting in the polymerization of free oxygens into Q_(Si)^(0) Q_(Si)^(1)non-bridging oxygens,which further polymerize into bridging oxygens and lead to the consolidation of simple structures and,resulting in a more complex slag structure.Both Raman spectroscopy analysis and molecular dynamics simulation results indicate that the degree of polymerization of[SiO_(4)]^(4-) and[AlO_(4)]^(4-) in the slag network structure is a crucial factor determining the fluidity of the slag.展开更多
In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under...In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under different influencing factors was designed with the aid of ICP-OES,XRD,and SEM-EDS.The experimental results show that,with the extension of leaching time,the continuous hydration reaction in the system enables the leaching amount of Si,Al,Mg,and Ca elements to show an overall downward trend.In the alkaline environment,the more sufficient hydration reaction consumes more soluble elements,resulting in a significantly smaller leaching amount than that in the neutral environment.Temperature is also an important factor affecting the leaching of elements.The rise of temperature promotes the dissolution of amorphous phases Si,Al,and Mg in the system,leading to increased leaching amount and higher consumption of C_(2)S and C_(3)S,generating more reaction products.In addition,the content and fineness of FETNS also have a significant effect on the element leaching of the composite cementitious system.More importantly,this paper clarifies the leaching safety of internal heavy metal elements when FETNS is used under the above conditions,which provides a scientific guarantee for the safe and efficient application of FETNS in building materials.展开更多
The current vanadium extraction process from sodium roasted vanadium slag poses risks such as ammonia pollution.This study proposes a novel calcium-based vanadium extraction and hydrolysis precipitation process,achiev...The current vanadium extraction process from sodium roasted vanadium slag poses risks such as ammonia pollution.This study proposes a novel calcium-based vanadium extraction and hydrolysis precipitation process,achieving clean and efficient vanadium recovery.The introduction of Ca O facilitates the targeted reconstruction and conversion of vanadium and calcium in the solution,forming acidsoluble calcium vanadate intermediates.Under optimal conditions,n(Ca)/n(V)ratio of 1.75,extraction temperature of 90℃,and extraction time of 90 min,the vanadium extraction ratio reached 99.83%.This process also separates vanadium from sodium and silicon,enabling one-step purification of the vanadium solution.Subsequent sulfuric acid leaching,conducted at p H of 4.0,90℃,and 60 min,achieved a vanadium leaching ratio of 99.72%,further separating vanadium from calcium and other impurities.Finally,the purified vanadium solution underwent hydrolysis precipitation at p H of 2.1 and 95℃for60 min,achieving a precipitation ratio of 98.69%.The calcined product yielded V_(2)O_(5) with a purity of 98.60%.Compared to the conventional sodium roasting—water leaching along with ammonium salt precipitation process,this innovative method eliminates ammonia-nitrogen wastewater emissions.This study provides a foundation for the development of new vanadium extraction technologies from vanadium slag.展开更多
NA novel smelting reduction process based on FeO-SiO2-Al2O3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and t...NA novel smelting reduction process based on FeO-SiO2-Al2O3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0：1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO-SiO2-Al2O3 slag system for the smelting process is appropriate under the conditions of m（FeO）：m（SiO2）=0.58：1？1.03：1, and 17.19%？21.52% Al2O3 content. The obtained alloy was mainly composed of Fe-Co-Cu-Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.展开更多
To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures rangi...To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.展开更多
The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied....The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.展开更多
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
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 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
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
A new electric arc furnace （EAF） steelmaking process with increasing hot metal charging ratio and improving slagging regime simultaneously was developed and applied in a 50 t electric arc furnace for more than a yea...A new electric arc furnace （EAF） steelmaking process with increasing hot metal charging ratio and improving slagging regime simultaneously was developed and applied in a 50 t electric arc furnace for more than a year at No. 1 Steelmaking Plant of Shanxi Taigang Stainless Corporation Limited. The essential fact of the new EAF steelmaking process was to charge hot metal in two portions or steps： firstly, 35wt%-40wt% hot metal was pretreated by blowing oxygen in a specially designed reactor for decar burization and improving hot metal temperature and melting premelted slag; secondly, 30wt% hot metal was charged into EAF with high basicity refining slags from ladle furnace （LF）-vacuum degassing furnace （VD） refining process. The results show that the hot metal charging ratio can reach to about 65wt%-70wt% for the new EAF steelrnaking process; meanwhile, the tap-to-tap time of a 50 t EAF can shorten by 5-10 min, the electricity consumption can decrease by 35-50 kW·h/t, the lime consumption can reduce by 10.5 kg/t of molten steel, and the content of harmful heavy metals in molten steel can be easily controlled to less than the upper limits of aimed steel specification or grade compared with the traditional EAF steelmaking process. In addition, the dephosphorization ability shows a slight strengthening, however, a small degree of lessening for desulphurization ability is observed for the new EAF steelmaking process, but the weakness of desulphurization ability cannot become an obstacle to its further application since a stronger desulphurization ability can be achieved during secondary refining of LF coupled with VD after EAF steelmaking process.展开更多
The effects of basicity and MgO content on the viscosity of SiO2-CaO-MgO-9wt%Al2O3 slags with basicity from 0.4 to 1.0 and MgO content from 13wt%to 19wt%were investigated using the rotating cylinder method. A correlat...The effects of basicity and MgO content on the viscosity of SiO2-CaO-MgO-9wt%Al2O3 slags with basicity from 0.4 to 1.0 and MgO content from 13wt%to 19wt%were investigated using the rotating cylinder method. A correlation between the viscosity and the slag structure was determined by Fourier transform infrared （FTIR） spectroscopy. It is indicated that the complex network structure of the slag melt is depolymerized into simpler network units with increasing basicity or MgO content, resulting in a continuous decrease in viscosity of the slag. The viscosity is strongly dependent on the combined action of basic oxide components in the slag. Under the present experimental conditions, increasing the basicity is found to be more effective than increasing the MgO content in decreasing the viscosity of the slag. At higher temperatures, the increase of basicity or MgO content does not appreciably decrease the viscosity of the slag, as it does at lower tem-peratures. The calculated activation energy of viscous flow is between 154 and 200 kJ＆#183;mol-1, which decreases with an increase in basicity from 0.4 to 1.0 at a fixed MgO content in the range of 13wt%to 19wt%.展开更多
Synthetic slag samples of the CaO-SiO2-MgO-A1203-Cr203 system were obtained to clarify the effect of FeO on the formation of spinel phases and Cr distribution. X-ray diffraction （XRD） and scanning electron microsco...Synthetic slag samples of the CaO-SiO2-MgO-A1203-Cr203 system were obtained to clarify the effect of FeO on the formation of spinel phases and Cr distribution. X-ray diffraction （XRD） and scanning electron microscopy （SEM） equipped with energy-dispersive spectroscopy （EDS）, as well as the thermodynamic software FactSage 6.2, were used for sample characterization. The results show that the addition of FeO can decrease the viscosity of molten slag and the precipitation temperatures of melilite and merwinite. The solidus temperature significantly decreases from 1400 to 1250℃ with the increase of FeO content from 0wt% to 6wt%. The addition of FeO could enhance the content of Cr in spinel phases and reduce the content of Cr in soluble minerals, such as merwinite, melilite, and dicalcium silicate. Hence, the addition of FeO is conducive to decreasing Cr leaching.展开更多
High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave a...High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.展开更多
The effects of MgO/Al2 O3 ratio on the viscous behaviors of MgO-Al2 O3-TiO2-CaO-SiO2 systems were investigated by the rotating cylinder method.Raman spectroscopy was used to analyze the structural characteristics of s...The effects of MgO/Al2 O3 ratio on the viscous behaviors of MgO-Al2 O3-TiO2-CaO-SiO2 systems were investigated by the rotating cylinder method.Raman spectroscopy was used to analyze the structural characteristics of slag and Factsage 7.0 was adopted to demonstrate the liquidus temperature of slag.The results show that the viscosity and activation energy for viscous flow decrease when the MgO/Al2O3 ratio increases from 0.82 to 1.36.The break point temperature and liquidus temperature of slag initially decrease and subsequently increase.The complex viscous structures are gradually depolymerized to simple structural units.In conclusion,with the increase of MgO/Al2O3 ratio,the degree of polymerization of slag decreases,which improves the fluidity of slag.The variations of liquidus temperature of slag lead to the same changes of break point temperature.展开更多
文摘The slagging/fouling due to the accession of fireside deposits on the steam boilers decreases boiler efficiency and availability which leads to unexpected shut-downs. Since it is inevitably associated with the three major factors namely the fuel characteristics, boiler operating conditions and ash behavior, this serious slagging/fouling may be reduced by varying the above three factors. The research develops a generic slagging/fouling prediction tool based on hybrid fuzzy clustering and Artificial Neural Networks (FCANN). The FCANN model presents a good accuracy of 99.85% which makes this model fast in response and easy to be updated with lesser time when compared to single ANN. The comparison between predictions and observations is found to be satisfactory with less input parameters. This should be capable of giving relatively quick responses while being easily implemented for various furnace types.
基金finally supported by the National Natural Science Foundation of China (Nos.52204309,52174277,52374300)。
文摘A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.
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funded by the National Natural Science Foundation of China(No.52374321)the National Key Research and Development Program of China(No.2024YFB3713602)the Youth Science and Technology Innovation Fund of Jianlong Group-University of Science and Technology Beijing(No.20231235).
文摘Slag viscosity plays a crucial role in the smelting process.A slag viscosity prediction model was developed by integrating hyperparameter optimization algorithms,machine learning,and SHapley Additive exPlanations(SHAP)analysis.The developed slag viscosity prediction models were evaluated using multiple statistical metrics,leading to the identification of the optimal model—Bayesian optimization-based categorical boosting(BO-CatBoost).And this model was further compared with existing models,including NPL model,FactSage+Roscoe-Einstein(RE)equation,artificial neural network model+RE equation,Riboud model+RE equation,and Zhang model.The results indicate that the slag viscosity prediction model based on BO-CatBoost outperforms all other models,achieving a coefficient of determination of 0.9897,a root mean square error of 1.0619,a mean absolute error of 0.6133,and a hit ratio of 95.1%.The global interpretability analysis of SHAP analysis was used to reveal the importance degree of different features on slag viscosity.The local interpretability analysis of SHAP analysis was used to obtain the quantitative influence of different features on slag viscosity in specific samples.The high-accuracy and interpretable slag viscosity prediction model developed is beneficial to the intelligent design of slag composition.
基金financially supported by the National Natural Science Foundation of China(No.52174299)the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization,China(No.2024P4FZG10).
文摘This study analyzes the influence of TiO_(2) and Al_(2)O_(3) contents on the microstructure of CaO-SiO_(2)-MgO-xwt%Al_(2)O_(3)-ywt%TiO_(2)(14≤x≤22,0≤y≤10)blast furnace slag systems based on the change of slag viscosity,Raman spectroscopy,and molecular dynamics.The Raman spectroscopy results indicate that an increase in TiO_(2) content leads to the gradual depolymerization of complex Q_(Si)^(3) Q_(Si)^(2) Q_(Si)^(0) Q_(Si)^(1)silicate structures(and)into simpler structures(and)in the slag.At the same time,the Al-O-Al bonds in the aluminate structures of the slag also depolymerize into simpler Al-O-forms,resulting in a decrease in the degree of polymerization of both silicates and aluminates.In contrast,an increase in Al_(2)O_(3) content generally results in an increased degree of polymerization for the silicates and aluminates.Molecular dynamics simulations of the polymerization and depolymerization processes in the microstructure of the blast fur-nace slag reveal that Si and Al mainly exist in tetrahedral[SiO_(4)]^(4-)and[AlO_(4)]^(4-),while Ti mainly exists in the form of simple pentaco-ordinate[TiO_(5)]^(6-)and hexacoordinate[TiO_(6)]^(8-).TiO_(2) exhibits basic properties in this system,whereas Al_(2)O_(3) demonstrates acidic behavior.The addition of TiO_(2) introduces free oxide ions into the system,causing the bridging oxygens to break into non-bridging oxygens,lead-Q_(Si)^(4) Q_(Si)^(3)ing to the depolymerization of complex structures and,which simplifies the slag structure.On the other hand,an increase in Al_(2)O_(3) content tends to capture or share the oxide ions within the system to form[AlO_(4)]^(4-),resulting in the polymerization of free oxygens into Q_(Si)^(0) Q_(Si)^(1)non-bridging oxygens,which further polymerize into bridging oxygens and lead to the consolidation of simple structures and,resulting in a more complex slag structure.Both Raman spectroscopy analysis and molecular dynamics simulation results indicate that the degree of polymerization of[SiO_(4)]^(4-) and[AlO_(4)]^(4-) in the slag network structure is a crucial factor determining the fluidity of the slag.
基金Funded by the Science and Technology Program of Gansu Province(Nos.23JRRA799 and 24JRRA213)the National Natural Science Foundation of China(Nos.52178216,52008196,and U21A20150)。
文摘In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under different influencing factors was designed with the aid of ICP-OES,XRD,and SEM-EDS.The experimental results show that,with the extension of leaching time,the continuous hydration reaction in the system enables the leaching amount of Si,Al,Mg,and Ca elements to show an overall downward trend.In the alkaline environment,the more sufficient hydration reaction consumes more soluble elements,resulting in a significantly smaller leaching amount than that in the neutral environment.Temperature is also an important factor affecting the leaching of elements.The rise of temperature promotes the dissolution of amorphous phases Si,Al,and Mg in the system,leading to increased leaching amount and higher consumption of C_(2)S and C_(3)S,generating more reaction products.In addition,the content and fineness of FETNS also have a significant effect on the element leaching of the composite cementitious system.More importantly,this paper clarifies the leaching safety of internal heavy metal elements when FETNS is used under the above conditions,which provides a scientific guarantee for the safe and efficient application of FETNS in building materials.
基金financially supported by the National Natural Science Foundation of China(52204309,52174277 and 52374300)Fundamental Funds for the Central Universities(N2425026)Liaoning Province Science and Technology Plan Joint Fund(2023-MSBA-052)。
文摘The current vanadium extraction process from sodium roasted vanadium slag poses risks such as ammonia pollution.This study proposes a novel calcium-based vanadium extraction and hydrolysis precipitation process,achieving clean and efficient vanadium recovery.The introduction of Ca O facilitates the targeted reconstruction and conversion of vanadium and calcium in the solution,forming acidsoluble calcium vanadate intermediates.Under optimal conditions,n(Ca)/n(V)ratio of 1.75,extraction temperature of 90℃,and extraction time of 90 min,the vanadium extraction ratio reached 99.83%.This process also separates vanadium from sodium and silicon,enabling one-step purification of the vanadium solution.Subsequent sulfuric acid leaching,conducted at p H of 4.0,90℃,and 60 min,achieved a vanadium leaching ratio of 99.72%,further separating vanadium from calcium and other impurities.Finally,the purified vanadium solution underwent hydrolysis precipitation at p H of 2.1 and 95℃for60 min,achieving a precipitation ratio of 98.69%.The calcined product yielded V_(2)O_(5) with a purity of 98.60%.Compared to the conventional sodium roasting—water leaching along with ammonium salt precipitation process,this innovative method eliminates ammonia-nitrogen wastewater emissions.This study provides a foundation for the development of new vanadium extraction technologies from vanadium slag.
基金Project(JS-211)supported by the State-Owned Enterprise Electric Vehicle Industry Alliance,China
文摘NA novel smelting reduction process based on FeO-SiO2-Al2O3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0：1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO-SiO2-Al2O3 slag system for the smelting process is appropriate under the conditions of m（FeO）：m（SiO2）=0.58：1？1.03：1, and 17.19%？21.52% Al2O3 content. The obtained alloy was mainly composed of Fe-Co-Cu-Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.
基金Project(2007CB613504)supported by the National Key Basic Research Program of ChinaProjects(51004033,50974035,51074047)supported by the National Natural Science Foundation of ChinaProject(2008BAB34B01)supported by National Science and Technology Support Plan of China during the 11th Five-Year Plan
文摘To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.
基金Project (41271330) supported by the National Natural Science Foundation of China
文摘The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.
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 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 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.
文摘A new electric arc furnace （EAF） steelmaking process with increasing hot metal charging ratio and improving slagging regime simultaneously was developed and applied in a 50 t electric arc furnace for more than a year at No. 1 Steelmaking Plant of Shanxi Taigang Stainless Corporation Limited. The essential fact of the new EAF steelmaking process was to charge hot metal in two portions or steps： firstly, 35wt%-40wt% hot metal was pretreated by blowing oxygen in a specially designed reactor for decar burization and improving hot metal temperature and melting premelted slag; secondly, 30wt% hot metal was charged into EAF with high basicity refining slags from ladle furnace （LF）-vacuum degassing furnace （VD） refining process. The results show that the hot metal charging ratio can reach to about 65wt%-70wt% for the new EAF steelrnaking process; meanwhile, the tap-to-tap time of a 50 t EAF can shorten by 5-10 min, the electricity consumption can decrease by 35-50 kW·h/t, the lime consumption can reduce by 10.5 kg/t of molten steel, and the content of harmful heavy metals in molten steel can be easily controlled to less than the upper limits of aimed steel specification or grade compared with the traditional EAF steelmaking process. In addition, the dephosphorization ability shows a slight strengthening, however, a small degree of lessening for desulphurization ability is observed for the new EAF steelmaking process, but the weakness of desulphurization ability cannot become an obstacle to its further application since a stronger desulphurization ability can be achieved during secondary refining of LF coupled with VD after EAF steelmaking process.
基金financially supported by the National Natural Science Foundation of China(No.51174148)
文摘The effects of basicity and MgO content on the viscosity of SiO2-CaO-MgO-9wt%Al2O3 slags with basicity from 0.4 to 1.0 and MgO content from 13wt%to 19wt%were investigated using the rotating cylinder method. A correlation between the viscosity and the slag structure was determined by Fourier transform infrared （FTIR） spectroscopy. It is indicated that the complex network structure of the slag melt is depolymerized into simpler network units with increasing basicity or MgO content, resulting in a continuous decrease in viscosity of the slag. The viscosity is strongly dependent on the combined action of basic oxide components in the slag. Under the present experimental conditions, increasing the basicity is found to be more effective than increasing the MgO content in decreasing the viscosity of the slag. At higher temperatures, the increase of basicity or MgO content does not appreciably decrease the viscosity of the slag, as it does at lower tem-peratures. The calculated activation energy of viscous flow is between 154 and 200 kJ＆#183;mol-1, which decreases with an increase in basicity from 0.4 to 1.0 at a fixed MgO content in the range of 13wt%to 19wt%.
基金the Chinese Scholarship Council for financial support
文摘Synthetic slag samples of the CaO-SiO2-MgO-A1203-Cr203 system were obtained to clarify the effect of FeO on the formation of spinel phases and Cr distribution. X-ray diffraction （XRD） and scanning electron microscopy （SEM） equipped with energy-dispersive spectroscopy （EDS）, as well as the thermodynamic software FactSage 6.2, were used for sample characterization. The results show that the addition of FeO can decrease the viscosity of molten slag and the precipitation temperatures of melilite and merwinite. The solidus temperature significantly decreases from 1400 to 1250℃ with the increase of FeO content from 0wt% to 6wt%. The addition of FeO could enhance the content of Cr in spinel phases and reduce the content of Cr in soluble minerals, such as merwinite, melilite, and dicalcium silicate. Hence, the addition of FeO is conducive to decreasing Cr leaching.
基金the National Key Basic Research Program of China (No. 2014CB238905)
文摘High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.
基金Projects(51574067,51904063)supported by the National Natural Science Foundation of ChinaProjects(N172503016,N172502005,N172506011)supported by Fundamental Research Funds for the Central Universities,ChinaProject(2018M640259)supported by China Postdoctoral Science Foundation
文摘The effects of MgO/Al2 O3 ratio on the viscous behaviors of MgO-Al2 O3-TiO2-CaO-SiO2 systems were investigated by the rotating cylinder method.Raman spectroscopy was used to analyze the structural characteristics of slag and Factsage 7.0 was adopted to demonstrate the liquidus temperature of slag.The results show that the viscosity and activation energy for viscous flow decrease when the MgO/Al2O3 ratio increases from 0.82 to 1.36.The break point temperature and liquidus temperature of slag initially decrease and subsequently increase.The complex viscous structures are gradually depolymerized to simple structural units.In conclusion,with the increase of MgO/Al2O3 ratio,the degree of polymerization of slag decreases,which improves the fluidity of slag.The variations of liquidus temperature of slag lead to the same changes of break point temperature.
