Phosphorus tends to migrate into metallic iron during the direct reduction of high-phosphorus oolitic iron ore,leading to undesirable phosphorus enrichment in metallic iron.However,the underlying reduction and migrati...Phosphorus tends to migrate into metallic iron during the direct reduction of high-phosphorus oolitic iron ore,leading to undesirable phosphorus enrichment in metallic iron.However,the underlying reduction and migration mechanisms remain poorly understood.Phosphorus behavior during coal-based reduction was systematically investigated through theoretical modeling and experimental approaches.Thermodynamic analysis revealed that the carbon reduction of solid Ca_(3)(PO_(4))_(2)to gaseous P_(2)requires temperatures exceeding 1400℃.Notably,this threshold significantly decreases to 1130.5℃in the presence of SiO_(2)and Al_(2)O_(3).Further investigations demonstrated that Ca_(3)(PO_(4))_(2)co-reduces with Fe_(x)O_(γ)in the presence of SiO_(2)-Al_(2)O_(3)-Fe_(x)O_(γ),forming Fe_(3)P(instead of gaseous P_(2))at a markedly lower temperature of 778.7℃.Mechanistic studies indicate that the inherent thermal stability of Ca_(3)(PO_(4))_(2)inhibits the generation of reactive[P_(2)O_(5)].However,SiO_(2)-Al_(2)O_(3)coexistence destabilizes Ca_(3)(PO_(4))_(2)while exponentially enhancing[P_(2)O_(5)]activity.This synergistic effect dramatically promotes the phosphorus mineral reduction.Characterization confirmed that Ca_(3)(PO_(4))_(2)migrated into the slag phase(4FeO·Al_(2)O_(3)·3SiO_(2)·CaO·P_(2)O_(5)).Subsequently,the reactive P_(2)O_(5)in slag is reduced with metallic iron to form Fe_(3)P,which further dissolves into theα-Fe matrix through solid-state diffusion,ultimately generating Fe-P solid solutions.展开更多
A low-grade nickel laterite ore was reduced at different reduction temperatures. The morphology of metallic particles was investigated by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）...A low-grade nickel laterite ore was reduced at different reduction temperatures. The morphology of metallic particles was investigated by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. Experimental results indicate that the metallic nickel and iron gradually assemble and grow into larger spherical particles with increasing temperature and prolonging time. After reduction, the nickel laterite ore obviously changes into two parts of Fe-Ni metallic particles and slag matrix. An obvious relationship is found between the reduction of iron magnesium olivine and its crystal chemical properties. The nickel and iron oxides are reduced to metallic by reductant, and the lattice of olivine is destroyed. The entire reduction process is comprised of oxide reduction and metallic phase growth.展开更多
In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applie...In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applied to investigate the rare earth minerals in Bayan Obo.The occurrence state and regularity of rare earth elements were analyzed under different reduction time. The results reveal that rare earth elements in rare earth minerals exist in RE（CO3）F（bastnaesite） and REPO4（monazite）. In this research, at 1,498 K with a C/O molar ratio（i.e., molar ratio of fixed carbon in the coal to reducible oxygen in the ore） of2.5, rare earth minerals primarily decompose into RE2O3at5 min. When the time is extended to 10 min, solid-phase reactions occur among RE2O3, CaO, and SiO2, and the resultant is cerium wollastonite（CaO·2RE2O3·3SiO2）. At reaction time 〉20 min, rare earth elements mainly exist in cerium wollastonite（CaO·2RE2O3·3SiO2）, and the grain size varies in the range of 10–30 μm. The results show that coal-based reduction is efficient to recover rare earth minerals in reduced materials.展开更多
The application of coal-based reduction in the efficient recovery of iron from refractory iron-bearing resources is comprehensively reviewed.Currently,the development and beneficiation of refractory iron-bearing resou...The application of coal-based reduction in the efficient recovery of iron from refractory iron-bearing resources is comprehensively reviewed.Currently,the development and beneficiation of refractory iron-bearing resources have attracted increasing attention.However,the effect of iron recovery by traditional beneficiation methods is unacceptable.Coal-based reduction followed by magnetic separation is proposed,which adopts coal as the reductant to reduce iron oxides to metallic iron below the melting temperature.The metallic iron particles aggregate and grow,and the particle size continuously increases to be suitable for magnetic separation.The optimization and application of coal-based reduction have been abundantly researched.A detailed literature study on coal-based reduction is performed from the perspectives of thermodynamics,reduction kinetics,growth of metallic iron particles,additives,and application.The coal-based reduction industrial equipment can be developed based on the existing pyrometallurgical equipments,rotary hearth furnace and rotary kiln,which are introduced briefly.However,coal-based reduction currently mainly adopts coal as a reductant and fuel,which may result in high levels of carbon dioxide emissions,energy consumption,and pollution.Technological innovation aiming at decreasing carbon dioxide emissions is a new trend of green and sustainable development of the steel industry.Therefore,the substitution of coal with clean energy(hydrogen,biomass,etc.)for iron oxide reduction shows promise in the future.展开更多
To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetic...To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA)and using the basic principle of solid phase mass transfer,respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction,and the migration process could be divided into three stages:phosphorus diffusing from the slag to the metallic interface,the formation of Fe P compounds at the slag metal interface and P diffusing from the slag metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature,while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.展开更多
Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reducti...Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions （i.e., reduction temperature, 1250℃; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%）. The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.展开更多
This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distr...This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distribution ratio in the metal, slag, and gas phases） during reduction was investigated in detail. Experimental results showed that the distribution behavior of phosphorus was strongly influenced by the reduction temperature, the reduction time, and the C/O molar ratio. A higher temperature and a longer reaction time were more favor-able for phosphorus reduction and enrichment in the metal phase. An increase in the C/O ratio improved phosphorus reduction but also hin-dered the mass transfer of the reduced phosphorus when the C/O ratio exceeded 2.0. According to scanning electron microscopy analysis, the iron ore was transformed from an integral structure to metal and slag fractions during the reduction process. Apatite in the ore was reduced to P, and the reduced P was mainly enriched in the metal phase. These results suggest that the proposed method may enable utilization of high-phosphorus-content oolitic iron ore resources.展开更多
To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure...To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the re- duced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumula- tive frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol^-1, and 922.05, respec- tively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.展开更多
The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorat...The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide （SiO2） to adjust the melting degree of file briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion （SiO2/（SiO2 ＋ A1203 ＋ MgO） mass ratio）. Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems axe avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500~C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The micro stxucture and phase txmlsformation of reduced briquette reveals that the aggregation and growth of ferroinckel particles were not significantly affected after adding SiO2 to the reduction process.展开更多
A water cooling treatment was applied in the coal-based reduction of high-chromium vanadium and titanium （V-Ti-Cr） iron ore from the Hongge region of Panzhihua, China. Its effects on the metallization ratio （η）, ...A water cooling treatment was applied in the coal-based reduction of high-chromium vanadium and titanium （V-Ti-Cr） iron ore from the Hongge region of Panzhihua, China. Its effects on the metallization ratio （η）, S removal ratio （Rs）, and P removal ratio （Rp） were studied and analyzed on the basis of chemical composition determined via inductively coupled plasma optical emission spectroscopy. The metallic iron particle size and the element distribution of Fe, V, Cr, and Ti in a reduced briquette after water cooling treatment at 1350℃ were determined and observed via scanning electron microscopy. The results show that the water cooling treatment improved the η, Rs, and Rp in the coal-based reduction of V-Ti-Cr iron ore compared to those obtained with a furnace cooling treatment. Meanwhile, the particle size of metallic iron obtained via the water cooling treatment was smaller than that of metallic iron obtained via the furnace cooling treatment; however, the particle size reached 70 μm at 1350℃, which is substantially larger than the minimum particle size required （20 μm） for magnetic separation. Therefore, the water cooling treatment described in this work is a good method for improving the quality of metallic iron in coal-based reduction and it could be applied in the coal-based reduction of V-Ti-Cr iron ore followed by magnetic separation.展开更多
An approach for coal-based direct reduction of vanadium−titanium magnetite(VTM)raw ore was proposed.Under the optimal reduction conditions with reduction temperature of 1140℃,reduction time of 3 h,C-to-Fe molar ratio...An approach for coal-based direct reduction of vanadium−titanium magnetite(VTM)raw ore was proposed.Under the optimal reduction conditions with reduction temperature of 1140℃,reduction time of 3 h,C-to-Fe molar ratio of 1.2꞉1,and pre-oxidation temperature of 900℃,the iron metallization degree is 97.8%.Ultimately,magnetic separation yields an iron concentrate with an Fe content of 76.78 wt.%and efficiency of 93.41%,while the magnetic separation slag has a Ti grade and recovery of 9.36 wt.%and 87.07%,respectively,with a titanium loss of 12.93%.This new strategy eliminates the beneficiation process of VTM raw ore,effectively reduces the Ti content in the iron concentrate,and improves the comprehensive utilization of valuable metals.展开更多
The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The ef...The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The effects of molar ratio of C to Fe n(C)/n(Fe) and temperature on the behaviors of vanadium and chromium during direct reduction and magnetic separation were investigated. The reduced samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM) and energy dispersive spectrometry(EDS) techniques. Experimental results indicate that the recoveries of vanadium and chromium rapidly increase from 10.0% and 9.6% to 45.3% and 74.3%, respectively, as the n(C)/n(Fe) increases from 0.8 to 1.4. At n(C)/n(Fe) of 0.8, the recoveries of vanadium and chromium are always lower than 10.0% in the whole temperature range of 1100-1250 °C. However, at n(C)/n(Fe) of 1.2, the recoveries of vanadium and chromium considerably increase from 17.8% and 33.8% to 42.4% and 76.0%, respectively, as the temperature increases from 1100 °C to 1250 °C. At n(C)/n(Fe) lower than 0.8, most of the FeO·V2O3 and FeO·Cr2O3 are not reduced to carbides because of the lack of carbonaceous reductants, and the temperature has little effect on the reduction behaviors of FeO·V2O3 and FeO·Cr2O3, resulting in very low recoveries of vanadium and chromium during magnetic separation. However, at higher n(C)/n(Fe), the reduction rates of FeO·V2O3 and FeO·Cr2O3 increase significatly because of the excess amount of carbonaceous reductants. Moreover, higher temperatures largely induce the reduction of FeO·V2O3 and FeO·Cr2O3 to carbides. The newly formed carbides are then dissolved in the γ(FCC) phase, and recovered accompanied with the metallic iron during magnetic separation.展开更多
Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model versi...Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model version 6 with a machine-learning-integrated four-mode version of the Modal Aerosol Module, we quantify global BC aging responses to emission reductions for 2011–2018 and for 2050 and 2100 under carbon neutrality. During 2011–18, global trends in BC aging degree(mass ratio of coatings to BC, R_(BC)) exhibited marked regional disparities, with a significant increase in China(5.4% yr^(-1)), which contrasts with minimal changes in the USA, Europe, and India. The divergence is attributed to opposing trends in secondary organic aerosol(SOA) and sulfate coatings, driven by regional changes in the emission ratios of corresponding coating precursors to BC(volatile organic compounds-VOCs/BC and SO_(2)/BC). Projections under carbon neutrality reveal that R_(BC) will increase globally by 47%(118%) in 2050(2100), with strong convergent increases expected across major source regions. The R_(BC) increase, primarily driven by enhanced SOA coatings due to sharper BC reductions relative to VOCs, will enhance the global BC mass absorption cross-section(MAC) by 11%(17%) in 2050(2100).Consequently, although the global BC burden will decline sharply by 60%(76%), the enhanced MAC partially offsets the magnitude of the decline in the BC direct radiative effect, resulting in the moderation of global BC DRE decreases to 88%(92%) of the BC burden reductions in 2050(2100). This study highlights the globally enhanced BC aging and light absorption capacity under carbon neutrality, thereby partly offsetting the impact of BC direct emission reductions on future changes in BC radiative effects globally.展开更多
In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride ...In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride molten salt as the reaction medium at 923 K.The study assessed the effects of lithium thermochemical reduction and electrolytic reduction of ZnO.The volatilization behavior of metal oxides in molten salts,the equivalent of a reducing agent,reduction time,amount of molten salt,stirring time,and the method of reduction feed were investigated for their impacts on the reduction yield and product composition.X-ray powder diffraction(XRD)analysis of the products showed that lithium reduction of ZnO not only produced metallic Zn but also formed a LiZn alloy.Electrolytic reduction can be used to obtain the metallic Zn product by controlling the potential below-2.2 V(vs Ag/Ag^(+)).Moreover,sintered oxides and higher electrode potentials could enhance the efficiency of electrolysis.Under the optimal reaction conditions determined experimentally,the lithium reduction experiment achieved a yield of 77.2%after a 12-h test,and the electrolytic reduction reached a yield of 85.4%after a 6-h test.展开更多
A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affordi...A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affording aldehydes in isolated yields of up to 88%with broad functional group tolerance,including cyano,halogen,alkenyl,ketone,and ester groups.Moreover,the method enables gram-scale aldehyde synthesis and shows high efficiency in reducing in situ generated acyl chlorides,thereby enhancing its synthetic practicality.展开更多
This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramia...This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.展开更多
This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the correspo...This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the corresponding ester[Fe_(2)(CO)_(6)(μ‑tedt)](2),where tedt=SCH_(2)CH(CH_(2)OOC(5‑C_(3)HNSCH_(3)))S.Further reactions of complex 2 with tri(ptolyl)phosphine(tp)or tris(4‑fluorophenyl)phosphine(fp)gave the phosphine‑substituted derivatives[Fe_(2)(CO)_(5)(tp)(μ‑tedt)](3)and[Fe_(2)(CO)_(5)(fp)(μ‑tedt)](4).The structures of the newly prepared complexes were elucidated by elemental analysis,NMR,IR,and X‑ray photoelectron spectroscopy.Moreover,single‑crystal X‑ray diffraction analysis confirmed their molecular structures,showing that they contain a di‑iron core ligated by a bridged dithiolate bearing a thiazole moiety and terminal carbonyls.The electrochemical and electrocatalytic proton reduction were probed by cyclic voltammetry,revealing that three complexes can catalyze the reduction of protons to H_(2) under the electrochemical conditions.For comparison,complex 4 possessed the best efficiency with a turnover frequency of 23.5 s^(-1)at 10 mmol·L^(-1)HOAc concentration.In addition,the fungicidal activity of these complexes was also investigated in this study.CCDC:2477511,2;2477512,3;2477513,4.展开更多
Experts and officials shared their insights on poverty reduction cooperation and sustainable development during the 2025 International Seminar on Global Poverty Reduction Partnerships.
Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in ac...Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.展开更多
Objective: To investigate the therapeutic advantages of closed reduction and Kirschner wire fixation versus open reduction and plate fixation in patients with hand surgery fractures. Methods: The sample was collected ...Objective: To investigate the therapeutic advantages of closed reduction and Kirschner wire fixation versus open reduction and plate fixation in patients with hand surgery fractures. Methods: The sample was collected from May 2021 to May 2025, consisting of 80 patients with hand surgery fractures. These patients were randomly divided into two groups using the red and blue ball method: the plate fixation group (40 cases, treated with open reduction and plate fixation) and the Kirschner wire fixation group (40 cases, treated with closed reduction and Kirschner wire fixation). The therapeutic effects between the two groups were randomly compared. Results: The Kirschner wire fixation group outperformed the plate fixation group in all indicators except for hand function scores (p < 0.05). There was no statistically significant difference in hand function scores between the two groups (p > 0.05). Conclusion: Compared with open reduction and plate fixation, closed reduction and Kirschner wire fixation for patients with hand surgery fractures achieves a more pronounced therapeutic effect, with advantages such as less trauma, shorter operation time, less bleeding, and a lower incidence of complications. It is suitable for hand surgery fractures with good stability. Open reduction and plate internal fixation have greater advantages in complex fractures and cases requiring high stability, and are worthy of promotion and application.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2023YFC3903900 and 2023YFC3903904)the National Natural Science Foundation Youth Foundation of China(No.52404356)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202216)。
文摘Phosphorus tends to migrate into metallic iron during the direct reduction of high-phosphorus oolitic iron ore,leading to undesirable phosphorus enrichment in metallic iron.However,the underlying reduction and migration mechanisms remain poorly understood.Phosphorus behavior during coal-based reduction was systematically investigated through theoretical modeling and experimental approaches.Thermodynamic analysis revealed that the carbon reduction of solid Ca_(3)(PO_(4))_(2)to gaseous P_(2)requires temperatures exceeding 1400℃.Notably,this threshold significantly decreases to 1130.5℃in the presence of SiO_(2)and Al_(2)O_(3).Further investigations demonstrated that Ca_(3)(PO_(4))_(2)co-reduces with Fe_(x)O_(γ)in the presence of SiO_(2)-Al_(2)O_(3)-Fe_(x)O_(γ),forming Fe_(3)P(instead of gaseous P_(2))at a markedly lower temperature of 778.7℃.Mechanistic studies indicate that the inherent thermal stability of Ca_(3)(PO_(4))_(2)inhibits the generation of reactive[P_(2)O_(5)].However,SiO_(2)-Al_(2)O_(3)coexistence destabilizes Ca_(3)(PO_(4))_(2)while exponentially enhancing[P_(2)O_(5)]activity.This synergistic effect dramatically promotes the phosphorus mineral reduction.Characterization confirmed that Ca_(3)(PO_(4))_(2)migrated into the slag phase(4FeO·Al_(2)O_(3)·3SiO_(2)·CaO·P_(2)O_(5)).Subsequently,the reactive P_(2)O_(5)in slag is reduced with metallic iron to form Fe_(3)P,which further dissolves into theα-Fe matrix through solid-state diffusion,ultimately generating Fe-P solid solutions.
基金Project(51134002)supported by the National Natural Science Foundation of ChinaProject(2012BAB14B02)supported by the Ministry of Science and Technology of ChinaProject(12120113086600)supported by Ministry of Land and Resources of China
文摘A low-grade nickel laterite ore was reduced at different reduction temperatures. The morphology of metallic particles was investigated by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. Experimental results indicate that the metallic nickel and iron gradually assemble and grow into larger spherical particles with increasing temperature and prolonging time. After reduction, the nickel laterite ore obviously changes into two parts of Fe-Ni metallic particles and slag matrix. An obvious relationship is found between the reduction of iron magnesium olivine and its crystal chemical properties. The nickel and iron oxides are reduced to metallic by reductant, and the lattice of olivine is destroyed. The entire reduction process is comprised of oxide reduction and metallic phase growth.
基金financially supported by the National Natural Science Foundation of China (Nos. 51204033 and 51134002)
文摘In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applied to investigate the rare earth minerals in Bayan Obo.The occurrence state and regularity of rare earth elements were analyzed under different reduction time. The results reveal that rare earth elements in rare earth minerals exist in RE（CO3）F（bastnaesite） and REPO4（monazite）. In this research, at 1,498 K with a C/O molar ratio（i.e., molar ratio of fixed carbon in the coal to reducible oxygen in the ore） of2.5, rare earth minerals primarily decompose into RE2O3at5 min. When the time is extended to 10 min, solid-phase reactions occur among RE2O3, CaO, and SiO2, and the resultant is cerium wollastonite（CaO·2RE2O3·3SiO2）. At reaction time 〉20 min, rare earth elements mainly exist in cerium wollastonite（CaO·2RE2O3·3SiO2）, and the grain size varies in the range of 10–30 μm. The results show that coal-based reduction is efficient to recover rare earth minerals in reduced materials.
基金financially supported by the National Natural Science Foundation of China (No. 52022019)the National Key R&D Program of China (No. 2021YFC2901000)the Fok Ying Tung Education Foundation (No. 161045)
文摘The application of coal-based reduction in the efficient recovery of iron from refractory iron-bearing resources is comprehensively reviewed.Currently,the development and beneficiation of refractory iron-bearing resources have attracted increasing attention.However,the effect of iron recovery by traditional beneficiation methods is unacceptable.Coal-based reduction followed by magnetic separation is proposed,which adopts coal as the reductant to reduce iron oxides to metallic iron below the melting temperature.The metallic iron particles aggregate and grow,and the particle size continuously increases to be suitable for magnetic separation.The optimization and application of coal-based reduction have been abundantly researched.A detailed literature study on coal-based reduction is performed from the perspectives of thermodynamics,reduction kinetics,growth of metallic iron particles,additives,and application.The coal-based reduction industrial equipment can be developed based on the existing pyrometallurgical equipments,rotary hearth furnace and rotary kiln,which are introduced briefly.However,coal-based reduction currently mainly adopts coal as a reductant and fuel,which may result in high levels of carbon dioxide emissions,energy consumption,and pollution.Technological innovation aiming at decreasing carbon dioxide emissions is a new trend of green and sustainable development of the steel industry.Therefore,the substitution of coal with clean energy(hydrogen,biomass,etc.)for iron oxide reduction shows promise in the future.
基金financially supported by the National Natural Science Foundation of China (No.51604063)
文摘To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA)and using the basic principle of solid phase mass transfer,respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction,and the migration process could be divided into three stages:phosphorus diffusing from the slag to the metallic interface,the formation of Fe P compounds at the slag metal interface and P diffusing from the slag metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature,while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.
基金supported by the National Natural Science Foundation of China(Nos.51134002 and 51074036)
文摘Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions （i.e., reduction temperature, 1250℃; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%）. The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.
基金financially supported by the National Natural Science Foundation of China(No.51134002)the Fundamental Research Funds for the Central Universi-ties of China(No.N120601004)
文摘This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distribution ratio in the metal, slag, and gas phases） during reduction was investigated in detail. Experimental results showed that the distribution behavior of phosphorus was strongly influenced by the reduction temperature, the reduction time, and the C/O molar ratio. A higher temperature and a longer reaction time were more favor-able for phosphorus reduction and enrichment in the metal phase. An increase in the C/O ratio improved phosphorus reduction but also hin-dered the mass transfer of the reduced phosphorus when the C/O ratio exceeded 2.0. According to scanning electron microscopy analysis, the iron ore was transformed from an integral structure to metal and slag fractions during the reduction process. Apatite in the ore was reduced to P, and the reduced P was mainly enriched in the metal phase. These results suggest that the proposed method may enable utilization of high-phosphorus-content oolitic iron ore resources.
基金financially supported by the National Natural Science Foundation of China(Nos.51134002 and 51604063)the Fundamental Research Funds for the Central Universities(No.N140108001)
文摘To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the re- duced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumula- tive frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol^-1, and 922.05, respec- tively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.
基金the National Natural Science Foundation of China(No.51234010)the Fundamental Research Funds for Central Universities(No.106112017CDJXY130001)for the financial support provided for this research
文摘The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide （SiO2） to adjust the melting degree of file briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion （SiO2/（SiO2 ＋ A1203 ＋ MgO） mass ratio）. Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems axe avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500~C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The micro stxucture and phase txmlsformation of reduced briquette reveals that the aggregation and growth of ferroinckel particles were not significantly affected after adding SiO2 to the reduction process.
基金financially supported by the Programs of the National Natural Science Foundation of China(Nos.51604065,51090384,51674084,51174051,and 51574082)the National Basic Research Program of China(No.2013CB632603)+1 种基金the Fundamental Funds for the Central Universities(Nos.150203003 and 150202001)the National Key Technology Research and development Program(No.2015BAB19B02)
文摘A water cooling treatment was applied in the coal-based reduction of high-chromium vanadium and titanium （V-Ti-Cr） iron ore from the Hongge region of Panzhihua, China. Its effects on the metallization ratio （η）, S removal ratio （Rs）, and P removal ratio （Rp） were studied and analyzed on the basis of chemical composition determined via inductively coupled plasma optical emission spectroscopy. The metallic iron particle size and the element distribution of Fe, V, Cr, and Ti in a reduced briquette after water cooling treatment at 1350℃ were determined and observed via scanning electron microscopy. The results show that the water cooling treatment improved the η, Rs, and Rp in the coal-based reduction of V-Ti-Cr iron ore compared to those obtained with a furnace cooling treatment. Meanwhile, the particle size of metallic iron obtained via the water cooling treatment was smaller than that of metallic iron obtained via the furnace cooling treatment; however, the particle size reached 70 μm at 1350℃, which is substantially larger than the minimum particle size required （20 μm） for magnetic separation. Therefore, the water cooling treatment described in this work is a good method for improving the quality of metallic iron in coal-based reduction and it could be applied in the coal-based reduction of V-Ti-Cr iron ore followed by magnetic separation.
基金funded by the National Natural Science Foundation of China(Nos.U20A20145,51774205)the Open Project from Engineering Research Center of the Ministry of Education,Sichuan University,China.
文摘An approach for coal-based direct reduction of vanadium−titanium magnetite(VTM)raw ore was proposed.Under the optimal reduction conditions with reduction temperature of 1140℃,reduction time of 3 h,C-to-Fe molar ratio of 1.2꞉1,and pre-oxidation temperature of 900℃,the iron metallization degree is 97.8%.Ultimately,magnetic separation yields an iron concentrate with an Fe content of 76.78 wt.%and efficiency of 93.41%,while the magnetic separation slag has a Ti grade and recovery of 9.36 wt.%and 87.07%,respectively,with a titanium loss of 12.93%.This new strategy eliminates the beneficiation process of VTM raw ore,effectively reduces the Ti content in the iron concentrate,and improves the comprehensive utilization of valuable metals.
基金Projects(2013CB632601,2013CB632604)supported by the National Basic Research Program of ChinaProject(51125018)supported by the National Science Foundation for Distinguished Young Scholars of China+1 种基金Project(KGZD-EW-201-2)supported by the Key Research Program of the Chinese Academy of SciencesProjects(51374191,21106167,51104139)supported by the National Natural Science Foundation of China
文摘The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The effects of molar ratio of C to Fe n(C)/n(Fe) and temperature on the behaviors of vanadium and chromium during direct reduction and magnetic separation were investigated. The reduced samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM) and energy dispersive spectrometry(EDS) techniques. Experimental results indicate that the recoveries of vanadium and chromium rapidly increase from 10.0% and 9.6% to 45.3% and 74.3%, respectively, as the n(C)/n(Fe) increases from 0.8 to 1.4. At n(C)/n(Fe) of 0.8, the recoveries of vanadium and chromium are always lower than 10.0% in the whole temperature range of 1100-1250 °C. However, at n(C)/n(Fe) of 1.2, the recoveries of vanadium and chromium considerably increase from 17.8% and 33.8% to 42.4% and 76.0%, respectively, as the temperature increases from 1100 °C to 1250 °C. At n(C)/n(Fe) lower than 0.8, most of the FeO·V2O3 and FeO·Cr2O3 are not reduced to carbides because of the lack of carbonaceous reductants, and the temperature has little effect on the reduction behaviors of FeO·V2O3 and FeO·Cr2O3, resulting in very low recoveries of vanadium and chromium during magnetic separation. However, at higher n(C)/n(Fe), the reduction rates of FeO·V2O3 and FeO·Cr2O3 increase significatly because of the excess amount of carbonaceous reductants. Moreover, higher temperatures largely induce the reduction of FeO·V2O3 and FeO·Cr2O3 to carbides. The newly formed carbides are then dissolved in the γ(FCC) phase, and recovered accompanied with the metallic iron during magnetic separation.
基金supported by the National Natural Science Foundation of China (42505149,41925023,U2342223,42105069,and 91744208)the China Postdoctoral Science Foundation (2025M770303)+1 种基金the Fundamental Research Funds for the Central Universities (14380230)the Jiangsu Funding Program for Excellent Postdoctoral Talent,and Jiangsu Collaborative Innovation Center of Climate Change。
文摘Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model version 6 with a machine-learning-integrated four-mode version of the Modal Aerosol Module, we quantify global BC aging responses to emission reductions for 2011–2018 and for 2050 and 2100 under carbon neutrality. During 2011–18, global trends in BC aging degree(mass ratio of coatings to BC, R_(BC)) exhibited marked regional disparities, with a significant increase in China(5.4% yr^(-1)), which contrasts with minimal changes in the USA, Europe, and India. The divergence is attributed to opposing trends in secondary organic aerosol(SOA) and sulfate coatings, driven by regional changes in the emission ratios of corresponding coating precursors to BC(volatile organic compounds-VOCs/BC and SO_(2)/BC). Projections under carbon neutrality reveal that R_(BC) will increase globally by 47%(118%) in 2050(2100), with strong convergent increases expected across major source regions. The R_(BC) increase, primarily driven by enhanced SOA coatings due to sharper BC reductions relative to VOCs, will enhance the global BC mass absorption cross-section(MAC) by 11%(17%) in 2050(2100).Consequently, although the global BC burden will decline sharply by 60%(76%), the enhanced MAC partially offsets the magnitude of the decline in the BC direct radiative effect, resulting in the moderation of global BC DRE decreases to 88%(92%) of the BC burden reductions in 2050(2100). This study highlights the globally enhanced BC aging and light absorption capacity under carbon neutrality, thereby partly offsetting the impact of BC direct emission reductions on future changes in BC radiative effects globally.
文摘In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride molten salt as the reaction medium at 923 K.The study assessed the effects of lithium thermochemical reduction and electrolytic reduction of ZnO.The volatilization behavior of metal oxides in molten salts,the equivalent of a reducing agent,reduction time,amount of molten salt,stirring time,and the method of reduction feed were investigated for their impacts on the reduction yield and product composition.X-ray powder diffraction(XRD)analysis of the products showed that lithium reduction of ZnO not only produced metallic Zn but also formed a LiZn alloy.Electrolytic reduction can be used to obtain the metallic Zn product by controlling the potential below-2.2 V(vs Ag/Ag^(+)).Moreover,sintered oxides and higher electrode potentials could enhance the efficiency of electrolysis.Under the optimal reaction conditions determined experimentally,the lithium reduction experiment achieved a yield of 77.2%after a 12-h test,and the electrolytic reduction reached a yield of 85.4%after a 6-h test.
文摘A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affording aldehydes in isolated yields of up to 88%with broad functional group tolerance,including cyano,halogen,alkenyl,ketone,and ester groups.Moreover,the method enables gram-scale aldehyde synthesis and shows high efficiency in reducing in situ generated acyl chlorides,thereby enhancing its synthetic practicality.
文摘This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.
文摘This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the corresponding ester[Fe_(2)(CO)_(6)(μ‑tedt)](2),where tedt=SCH_(2)CH(CH_(2)OOC(5‑C_(3)HNSCH_(3)))S.Further reactions of complex 2 with tri(ptolyl)phosphine(tp)or tris(4‑fluorophenyl)phosphine(fp)gave the phosphine‑substituted derivatives[Fe_(2)(CO)_(5)(tp)(μ‑tedt)](3)and[Fe_(2)(CO)_(5)(fp)(μ‑tedt)](4).The structures of the newly prepared complexes were elucidated by elemental analysis,NMR,IR,and X‑ray photoelectron spectroscopy.Moreover,single‑crystal X‑ray diffraction analysis confirmed their molecular structures,showing that they contain a di‑iron core ligated by a bridged dithiolate bearing a thiazole moiety and terminal carbonyls.The electrochemical and electrocatalytic proton reduction were probed by cyclic voltammetry,revealing that three complexes can catalyze the reduction of protons to H_(2) under the electrochemical conditions.For comparison,complex 4 possessed the best efficiency with a turnover frequency of 23.5 s^(-1)at 10 mmol·L^(-1)HOAc concentration.In addition,the fungicidal activity of these complexes was also investigated in this study.CCDC:2477511,2;2477512,3;2477513,4.
文摘Experts and officials shared their insights on poverty reduction cooperation and sustainable development during the 2025 International Seminar on Global Poverty Reduction Partnerships.
基金supported by the National Key R&D Program of China(No.2023YFE0112100)the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Devel-opment Special Fund of Xiamen(No.23YYST064QCB36).
文摘Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.
文摘Objective: To investigate the therapeutic advantages of closed reduction and Kirschner wire fixation versus open reduction and plate fixation in patients with hand surgery fractures. Methods: The sample was collected from May 2021 to May 2025, consisting of 80 patients with hand surgery fractures. These patients were randomly divided into two groups using the red and blue ball method: the plate fixation group (40 cases, treated with open reduction and plate fixation) and the Kirschner wire fixation group (40 cases, treated with closed reduction and Kirschner wire fixation). The therapeutic effects between the two groups were randomly compared. Results: The Kirschner wire fixation group outperformed the plate fixation group in all indicators except for hand function scores (p < 0.05). There was no statistically significant difference in hand function scores between the two groups (p > 0.05). Conclusion: Compared with open reduction and plate fixation, closed reduction and Kirschner wire fixation for patients with hand surgery fractures achieves a more pronounced therapeutic effect, with advantages such as less trauma, shorter operation time, less bleeding, and a lower incidence of complications. It is suitable for hand surgery fractures with good stability. Open reduction and plate internal fixation have greater advantages in complex fractures and cases requiring high stability, and are worthy of promotion and application.
