The suspension stage of copper flash smelting was examined by roasting a high arsenic copper smelting feed mixture at 500-900°C for 0-20 s in nitrogen and air atmospheres.The enrichment of copper,lead,zinc,arseni...The suspension stage of copper flash smelting was examined by roasting a high arsenic copper smelting feed mixture at 500-900°C for 0-20 s in nitrogen and air atmospheres.The enrichment of copper,lead,zinc,arsenic,and sulfur in the quenched calcine was determined via chemical analyses.Pyrite and chalcopyrite were the main minerals in the feed mixture,and about 55 wt.%of arsenic was in tennantite.The stability of the feed and the formation of S_(2) and SO_(2)during roasting were surveyed by thermal analysis combined with mass spectrometry.Selected pure impurity sulfides were studied for reference purposes.Results indicated that arsenic was released more easily in inert atmosphere compared to air,in which oxidation products of sulfides captured the released gaseous arsenic.Kinetics analyses showed that the third-order chemical reaction and three-dimensional diffusion models were found as the most suitable mechanism functions of arsenic volatilization in inert and air atmospheres,respectively.展开更多
Antimony smelting activities damage the soil and vegetation surroundings while generating economic value.However,no standardizedmethods are available to diagnose the extent of soil degradation at antimony smelting sit...Antimony smelting activities damage the soil and vegetation surroundings while generating economic value.However,no standardizedmethods are available to diagnose the extent of soil degradation at antimony smelting sites.This study developed a standardized framework for assessing soil quality by consideringmicrobial-induced resilience and heavymetal contamination at Xikuangshan antimony smelting site.The soil resilience index(SRI)and soil contamination index(SCI)were calculated byMinimum Data Set and geo-accumulation model,respectively.After standardized by a multi-criteria quantitative procedure of modified Nemerow’s pollution index(NPI),the integrated assessment of soil quality index(SQI),which is the minimumof SRINPI and SCINPI,was achieved.The results showed that Sb and As were the prominent metal(loid)pollutants,and significant correlations between SQI and SRI indicated that the poor soil quality was mainly caused by the low level of soil resilience.The primary limiting factors of SRI were Fungi in high andmiddle contaminated areas,and Skermanella in low contaminated area,suggesting that the weak soil resilience was caused by low specific microbial abundances.Microbial regulation and phytoremediation are greatly required to improve the soil quality at antimony smelting sites from the perspectives of pollution control and resilience improvement.This study improves our understanding of ecological effects of antimony smelting sites and provides a theoretical basis for ecological restoration and sustainable development of mining areas.展开更多
Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across...Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.展开更多
Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs prod...Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs production and have high recycling value.In this study,smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe_(2)O_(3).This separates REEs into a slag phase from an iron-rich metallic phase.B_(2)O_(3) was also added to the system as a flux to lower the slag melting temperature.This minimizes REEs loss to the metallic phase and allows a more efficient phase separation.The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB(NdCeFeB)magnets.At 1350℃and for 1 h,the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe_(2)O_(3) and 40 wt%of B_(2)O_(3).Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX)analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron.After the selective removal of iron into the metallic phase,REEs are recovered from the slag phase through an acid leaching process allowing>99%of REEs recovery.Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique.The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.展开更多
To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction re...To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction reaction process of the Fe-Si bath and the migration behavior of valuable elements in the solidification and crystallization process of silicothermic reduction tailings were investigated,and a treatment method for efficiently separating and enriching REE,Nb and Ti was explored.Thermodynamic analysis indicated that at 1600℃,with a 6 wt.%addition of Si as the reducing agent,the niobium oxide in the REE-Nb-Ti-containing slag could be selectively reduced to metallic Nb.In the Fe-Si bath reduction process,the Nb mass fraction in the metal phase increased with prolonged reaction time,peaking at 2.77%,while the Ti mass fraction consistently stayed below 0.12%.Lowering the w(CaO)/w(SiO_(2))enhanced the migration of Nb from slag to metal phase and reduced the Ti impurities.During solidification and crystallization,a significant quantity of perovskite precipitated from reduction tailings,with the REE dissolving into this perovskite.By adjusting the w(CaO)/w(SiO_(2))in tailings to 1.2-1.9 and maintaining a temperature of 1100℃for 4 h,the perovskite area fraction in the final slag could exceed 37%.Finally,a method was proposed to separate and enrich valuable elements in REE-Nb-Ti-containing slags via Fe-Si bath smelting reduction and crystallization control.展开更多
Non-ferrous metal smelting poses significant risks to public health.Specifically,the copper smelting process releases arsenic,a semi-volatile metalloid,which poses an emerging exposure risk to both workers and nearby ...Non-ferrous metal smelting poses significant risks to public health.Specifically,the copper smelting process releases arsenic,a semi-volatile metalloid,which poses an emerging exposure risk to both workers and nearby residents.To comprehensively understand the internal exposure risks of metal(loid)s from copper smelting,we explored eighteen metal(loid)s and arsenic metabolites in the urine of both occupational and non-occupational populations using inductively coupled plasma mass spectrometry with high-performance liquid chromatography and compared their health risks.Results showed that zinc and copper(485.38 and 14.00μg/L),and arsenic,lead,cadmium,vanadium,tin and antimony(46.80,6.82,2.17,0.40,0.44 and 0.23μg/L,respectively)in workers(n=179)were significantly higher compared to controls(n=168),while Zinc,tin and antimony(412.10,0.51 and 0.15μg/L,respectively)of residents were significantly higher than controls.Additionally,workers had a higher monomethyl arsenic percentage(MMA%),showing lower arsenic methylation capacity.Source appointment analysis identified arsenic,lead,cadmium,antimony,tin and thallium as co-exposure metal(loid)s from copper smelting,positively relating to the age of workers.The hazard index(HI)of workers exceeded 1.0,while residents and control were approximately at 1.0.Besides,all three populations had accumulated cancer risks exceeding 1.0×10^(-4),and arsenite(AsIII)was the main contributor to the variation of workers and residents.Furthermore,residents living closer to the smelting plant had higher health risks.This study reveals arsenic exposure metabolites and multiple metals as emerging contaminants for copper smelting exposure populations,providing valuable insights for pollution control in non-ferrous metal smelting.展开更多
The properties of direct reduced iron(DRI)smelting slag are important in the DRI melting process for molten iron production to ensure the slag-iron separation and quality of molten iron.The influence of binary basicit...The properties of direct reduced iron(DRI)smelting slag are important in the DRI melting process for molten iron production to ensure the slag-iron separation and quality of molten iron.The influence of binary basicity on the viscosity and sulfide capacity of CaO-SiO_(2)-MgO-Al_(2)O_(3)-FeO slag was investigated by the high-temperature experiments,structural analysis and thermodynamic calculation.The viscosity of the slag decreased rapidly with an increase in basicity from 0.4 to 0.8,and this trend became slow as the basicity further increased to 1.2.For the acidic slag with basicity of 0.4 and 0.6,the viscosity at 1500℃ was higher than 0.6 Pa s,which was harmful for the fluidity of slag melt.The slags with basicity of 0.8,1.0 and 1.2 at 1500℃ showed the low viscosity of less than 0.6 Pa s.For the basic slag with basicity of 1.0 and 1.2,the rapid precipitation of melilite led to the abrupt increase behavior of the viscosity,and the acidic slag showed the gentle temperature-viscosity curves.The Raman analysis revealed that the conversion from Q^(3) to Q^(2),Q^(1) and Q^(0) mainly occurred with the basicity increasing from 0.4 to 0.8,and the conversion from Q^(2) to Q^(1) and Q^(0) was dominant with further increase in basicity to 1.2,decreasing the degree of polymerization.The sulfide capacity was improved with the increasing basicity due to the increase in O^(2-)ions,and CaS could be formed dominantly for S^(2-)stabilization in present slag.The sulfur partition ratio was derived from sulfide capacity,and the values of sulfur partition ratio at basicity of 0.4 and 0.6 were much smaller than those at basicity of 0.8,1.0 and 1.2,indicating a weak desulfurization ability of the slag with a low basicity.展开更多
Stainless steel,known for its exceptional properties and diverse applications,conventionally requires a multistage process that generates considerable CO_(2) emissions by using fossil-based carbon reductants.This stud...Stainless steel,known for its exceptional properties and diverse applications,conventionally requires a multistage process that generates considerable CO_(2) emissions by using fossil-based carbon reductants.This study investigated hydrogen plasma smelting reduction as a novel,sustainable,and efficient method for producing stainless steel directly from lateritic nickel and chromite ores.The research aimed to examine the effect of ore proportion on AISI 300 series stainless steel production and assess the reduction process over time through thermochemical calculations and experimental studies.Results showed that increasing the proportion of chromite ore in the feed raises Cr content and reduces Ni content in metals while increasing Cr_(2)O_(3) and Al_(2)O_(3) content in oxides.A briquette comprising 30wt%chromite ore and 70wt%calcined nickel ore yields better results for AISI 300 stainless steel,with Fe,Cr,Ni,and Si content of 62.95wt%,19.37wt%,11.83wt%,and 0.72wt%,respectively,after 180 s of hydrogen plasma exposure.Nearly all NiO compounds are converted into Ni after 60 s of smelting reduction,whereas FeO compounds are almost fully converted into Fe after 120 s of smelting reduction.AISI 300 series stainless steel is successfully produced after 120 s of reduction,achieving Fe,Cr,Ni,and Si content of 64.36wt%,21.92wt%,10.08wt%,and 0.61wt%,respectively.Process optimization remains promising because the Cr_(2)O_(3) content in the slag is still relatively high at 15.52wt%.This ultrafast and direct production method holds considerable potential to transform stainless steel production by reducing environmental impact and enhancing process efficiency.Specifically,the method eliminates the use of an argon oxygen decarburization converter and vacuum oxygen decarburization in stainless steelmaking.展开更多
The semi-molten smelting process of a mixture of saprolitic and limonitic laterite ores was systematically investigated and the effect of slag basicity was deeply analyzed.The results indicate that the slag system can...The semi-molten smelting process of a mixture of saprolitic and limonitic laterite ores was systematically investigated and the effect of slag basicity was deeply analyzed.The results indicate that the slag system can be located in the liquidus region of low melting-point diopside(CaMgSi_(2)O_(6))when slag basicity is kept at 0.3 and limonitic laterite mass fraction is not less than 10%.When the reduction temperature,C/O mass ratio,limonitic laterite mass fraction and slag basicity are kept at the optimum values of 1300℃,0.86,20%and 0.3,respectively,ferronickel products with grades 6.42%Ni and 86.99%Fe are prepared.The recovery rates of Ni and Fe reach 88.60%and 72.25%,respectively.展开更多
Under complicated field conditions,such as the coupled effects of freeze-thaw cycles(FTs)and acidification,the leaching behavior of potentially toxic element(PTEs)from indigenous Zn smelting slags(ZSS)was intricately ...Under complicated field conditions,such as the coupled effects of freeze-thaw cycles(FTs)and acidification,the leaching behavior of potentially toxic element(PTEs)from indigenous Zn smelting slags(ZSS)was intricately connected to the mineralogy(e.g.,the composition,assemblage,microstructure of mineral particles).In this study,FTs tests were carried out to explore the interactions between PTEs release and ZSSmineralogy.Subsequently,advanced characterization techniqueswere adopted to quantify the mineralogy andmicrostructure of ZSS.The results indicated that ZSS were mainly composed of silicate minerals(e.g.,quartz,biotite and chlorite)and secondary Fe(III)oxyhydroxides(e.g.,magnetite and limonite),accounting for 67.48% and 24.23%,respectively.The occurrence mode analysis revealed that 81.95%of As,21.31%of Pb and 7.77% of Zn were hosted in limonite.About 37.89%,59.34% and 34.50% of Cd,Pb and Zn were associated with carbonate bound fractions.Under FTs interacting with different pH conditions,the leaching concentrations of As,Cd,Cu,Pb and Zn did not significantly increase with the increase in FTs and pH.The microstructure damage of mineral particles in ZSS with the higher porosity was caused by both FTs and proton corrosion.More importantly,the geochemical modeling results suggested that the precipitation of hematite and magnetite,as well as the dissolution of arsenolite,might have little impacts on PTEs release under FTs and FTs with acidification.This work would provide a deeper understanding of PTEs release from smelting waste slags under complex physicochemical interactions.展开更多
The melting and separation behavior of vanadium-titanium magnetite pellets directed at an efficient extraction of vanadium and titanium was systematically investigated.Applying FactSage simulations and experiments,the...The melting and separation behavior of vanadium-titanium magnetite pellets directed at an efficient extraction of vanadium and titanium was systematically investigated.Applying FactSage simulations and experiments,the smelting separation of three pre-reduced pellets from different regions was analyzed.The simulations demonstrate that FeTi2O5 is converted to TiC at low temperatures,necessitating suppression of this step.Experiments under optimized conditions(1590-1690°C,20-25 min,2%coke,basicity 0.4-0.6,and 3.0%-6.0%MgO)yield iron grade of 92.35%-95.06%,titanium grade of 34.37%-39.89%,and vanadium grade of 0.56%-1.52%,with recoveries of 99.52%-99.60%,94.08%-98.96%,and 92.63%-94.38%for iron,titanium and vanadium,respectively.The titanium in the slag,primarily in the form of anosovite,is suitable for sulfuric acid-based titanium white production.An increase in basicity,MgO content,and pellet metallization serves to improve vanadium recovery in melted iron but lowers the titanium grade in the slag.The overall process effectively utilizes vanadium and titanium resources under optimized conditions.展开更多
A process for treating cyanide tailings was proposed.The process essentially implicates reduction smelting which involves volatilizing silver,lead,and zinc in the cyanide tailings at high temperatures.Meanwhile,gold a...A process for treating cyanide tailings was proposed.The process essentially implicates reduction smelting which involves volatilizing silver,lead,and zinc in the cyanide tailings at high temperatures.Meanwhile,gold and copper combine with the reduced iron to form a metal phase,allowing for the simultaneous recovery of polymetallic elements.The experimental results indicate that the process works optimally with a coke powder of 7.5 wt.%,an alkalinity of 1.0,a melting temperature of 1450℃,and a melting time of 60 min.Under these conditions,more than 99% of gold,77% of copper and 94% of iron are incorporated into pig iron.In the meantime,the volatilization rate of silver exceeds 90%,while lead and zinc are essentially completely volatilized.The primary component of the by-product smelting slag is akermanite,which exhibits lower leaching toxicity than the national standard and belongs to general solid waste.Additionally,taking the trapping process of iron to copper as a case study,the mechanism of iron trapping is methodically examined and divided into three processes:smelting reduction,migration capture,and condensation deposition.展开更多
Heavy metal(loid)s contamination is a constant issue at smelting sites.It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental manageme...Heavy metal(loid)s contamination is a constant issue at smelting sites.It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites.In this study,203 soil samples from 57 sites were collected in a typical lead smelting site.The findings demonstrated that there were significant Pb,Zn,Cd,and As contamination in soil samples.The spatial distribution of heavy metal(loid)s showed strong spatial heterogeneity,the contaminated soil areas of Pb,As,Cd,and Zn were 99.5%,98.9%,85.3%,and 72.4%,respectively.Pb,Cd,and As contamination of the soil reached a depth of 5 m,which migrated from the surface to deep soil layers.The leaching contents of Zn,Pb,and As decreased obviously in 3-4 m soil layer,but the leaching content of Cd was still high,which indicated the high migration of Cd.With the increase of depth,the proportion of acid soluble fraction of heavy metal(loid)s decreased,and the residual fraction increased.The acid soluble fraction of Cd accounted for a higher proportion,and As mainly existed in reducible and residual fractions in soil.According to the calculation of the migration factor,the migration of heavy metal(loid)s in soils were ordered as Cd>Zn>Pb>As.The outcomes are advantageous for risk reduction and site remediation for non-ferrous metal smelting sites.展开更多
The lack of understanding of heavy metal speciation and solubility control mechanisms in smelting soils limits the effective pollution control.In this study smelting soils were investigated by an advanced mineralogica...The lack of understanding of heavy metal speciation and solubility control mechanisms in smelting soils limits the effective pollution control.In this study smelting soils were investigated by an advanced mineralogical analysis(AMICS),leaching tests and thermodynamic modelling.The aims were to identify the partitioning and release behaviour of Pb,Zn,Cd and As.The integration of multiple techniques was necessary and displayed coherent results.In addition to the residual fraction,Pb and Zn were predominantly associated with reducible fractions,and As primarily existed as the crystalline iron oxide-bound fractions.AMICS quantitative analysis further confirmed that Fe oxyhydroxides were the common dominant phase for As,Cd,Pb and Zn.In addition,a metal arsenate(paulmooreite)was an important mineral host for Pb and As.The pH-stat leaching indicted that the release of Pb,Zn and Cd increased towards low pH values while release of As increased towards high p H values.The separate leaching schemes were associated with the geochemical behaviour under the control of minerals and were confirmed by thermodynamic modelling.PHREEQC calculations suggested that the formation of arsenate minerals(schultenite,mimetite and koritnigite)and the binding to Fe oxyhydroxides synchronously controlled the release of Pb,Zn,Cd and As.Our results emphasized the governing role of Fe oxyhydroxides and secondary insoluble minerals in natural attenuation of heavy metals,which provides a novelty strategy for the stabilization of multi-metals in smelting sites.展开更多
The prevention of hot cracking formation is of utmost importance in the production of the new Ni-Co based superalloys through the utilization of the electron beam smelting layered solidification technique(EBSL),as it ...The prevention of hot cracking formation is of utmost importance in the production of the new Ni-Co based superalloys through the utilization of the electron beam smelting layered solidification technique(EBSL),as it ensures exceptional homogeneity and dependable consistency of the specimens.In contrast to previous studies that focused on minimizing the liquid film and solidification range,our methodology adopts a distinct approach.In this research,a novel methodology was employed to mitigate internal stresses through the implementation of equiaxed grain layers via an alternately reduced cooling method.This ultimately resulted in the elimination of hot cracking.To be more specific,the transition from a columnar to an equiaxed structure was observed during the layer-by-layer construction process in the fabrication of the new Ni-Co based superalloy in EBSL.The EBSL-Ni-Co superalloy,when subjected to the alternating reduction cooling method,exhibited an internal stress of 49 MPa.This value represents a significant reduction of 83.8%compared to the internal stress observed when employing the linear reduction cooling method.Additionally,the solvus temperature of theγ-γ’eutectic phases in EBSL-Ni-Co superalloys produced by the alternating reduction cooling method is significantly higher.Intriguingly,the Nth layer of the EBSL-Ni-Co based superalloys produced by EBSL simultaneously heats treated with the preceding layers.And the low melting point phase gradually dissolved back into the matrix.The implementation of an alternating reduced cooling method successfully mitigated the formation of the liquid film in theγ-γ’eutectic phase and the buildup of internal stresses in the EBSL-Ni-Co superalloy during its manufacturing process.These discoveries open up a novel preparation procedure pathway for the manufacture of crack-free superalloys with superior mechanical characteristics using EBSL.展开更多
The separation of halogens and recovery of heavy metals from secondary copper smelting(SCS)dust using a sulfating roasting−water leaching process were investigated.The thermodynamic analysis results confirm the feasib...The separation of halogens and recovery of heavy metals from secondary copper smelting(SCS)dust using a sulfating roasting−water leaching process were investigated.The thermodynamic analysis results confirm the feasibility of the phase transformation to metal sulfates and to gaseous HF and HCl.Under the sulfating roasting conditions of the roasting temperature of 250℃ and the sulfuric acid excess coefficient of 1.8,over 74 wt.%of F and 98 wt.%of Cl were volatilized into flue gas.Approximately 98.6 wt.%of Zn and 96.5 wt.%of Cu in the roasting product were dissolved into the leaching solution after the water leaching process,while the leaching efficiencies of Pb and Sn were only 0.12%and 0.22%,respectively.The mechanism studies indicate the pivotal effect of roasting temperature on the sulphation reactions from various metal species to metal sulfates and the salting out reactions from various metal halides to gaseous hydrogen halides.展开更多
A general prediction model for seven heavy metals was established using the heavy metal contents of 207soil samples measured by a portable X-ray fluorescence spectrometer(XRF)and six environmental factors as model cor...A general prediction model for seven heavy metals was established using the heavy metal contents of 207soil samples measured by a portable X-ray fluorescence spectrometer(XRF)and six environmental factors as model correction coefficients.The eXtreme Gradient Boosting(XGBoost)model was used to fit the relationship between the content of heavy metals and environment characteristics to evaluate the soil ecological risk of the smelting site.The results demonstrated that the generalized prediction model developed for Pb,Cd,and As was highly accurate with fitted coefficients(R^(2))values of 0.911,0.950,and 0.835,respectively.Topsoil presented the highest ecological risk,and there existed high potential ecological risk at some positions with different depths due to high mobility of Cd.Generally,the application of machine learning significantly increased the accuracy of pXRF measurements,and identified key environmental factors.The adapted potential ecological risk assessment emphasized the need to focus on Pb,Cd,and As in future site remediation efforts.展开更多
The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method.The essenti...The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method.The essential aspects of the fluid phase(e.g.,splashing volume,dead zone of copper slag,and gas penetration depth)were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases.The results illustrated that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance,respectively.The expansion of larger ones as well as the shrinking of smaller ones combine to cause the contraction of the bubble waist.Compared to the results of the case with a fixed gas injection velocity(V_(g)=58 m/s),the splashing volume and dead zone volume of the slag under the V_(g)=58+10sin(2πt)condition are reduced by 24.9%and 23.5%,respectively,where t represents the instant time.Gas penetration depth and slag motion velocity of the latter are 1.03 and 1.31 times high-er than those of the former,respectively.展开更多
A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effec...A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effect.Its modeling results were verified with theoretical correlations and experiments,and the nozzle-eroded states in practice were also involved in the analysis.Through comparison,it is confirmed that the thermal expansion effect influences the flow pattern significantly,which may lead to the backward motion of airflow and create a potential risk to production safety.Consequently,the influences of air injection velocity and furnace width on airflow behavior were investigated to provide operating and design guidance.It is found that the thin layer melt,which avoids high-rate oxygen airflow eroding nozzles,shrinks as the injection velocity increases,but safety can be guaranteed when the velocity ranges from 175 to 275 m/s.Moreover,the isoline patterns and heights of thin layers change slightly when the furnace width increases from 2.2 to 2.8 m,indicating that the furnace width shows a limited influence on production safety.展开更多
This research was performed to investigate the optimization of copper recovery from copper smelting slag(CSS)with a deep eutectic solvent as a green reagent.The effect of important parameters on the leaching efficienc...This research was performed to investigate the optimization of copper recovery from copper smelting slag(CSS)with a deep eutectic solvent as a green reagent.The effect of important parameters on the leaching efficiency of copper and zinc(as well as dissolution of iron),such as leaching time,leaching temperature,solid/liquid ratio,and particle size was studied.In order to model the copper recovery,an optimization method was used.According to the chemical analysis of CSS,the slag contains 0.9%copper,3.3%zinc,and 36.7%iron.Also,it was found that the CSS is mainly composed of Fe2SiO4,Fe3O4 and SiO2.Copper-containing structures were determined as CuO and CuS.As a result of leaching experiments,80%copper and 61%zinc recoveries were obtained at 48 h,95℃,1/25 g·ml^(-1),and-33 mm.It is noted that the iron and silicon dissolution remained negligible under the selected conditions.According to the mathematical model,the highest copper leaching efficiency(up to 100%)could be under optimum working conditions as 48.5℃leaching temperature,40.1 h leaching duration,and 62.3 ml·g^(-1)solid/liquid ratio.Also,the proposed model revealed that a wide range of experimental levels can be used as leaching parameter to get desired metal leaching efficiency.展开更多
基金support from the Research Foundation for Doctor of Nanyang Institute of Technology,China(No.NGBJ-2022-27)the National Key Research and Development Program of China(No.2023YFC3904002)+3 种基金the National Natural Science Foundation of China(Nos.52064038,52364056)the Science and Technology Research Project of Henan Province,China(No.252102320113)the Key Scientific Research Project Plan of Colleges and Universities in Henan Province,China(No.25B610009)Jiangxi Provincial Natural Science Foundation,China(Nos.20232BCJ22049,20232ACB214009).
文摘The suspension stage of copper flash smelting was examined by roasting a high arsenic copper smelting feed mixture at 500-900°C for 0-20 s in nitrogen and air atmospheres.The enrichment of copper,lead,zinc,arsenic,and sulfur in the quenched calcine was determined via chemical analyses.Pyrite and chalcopyrite were the main minerals in the feed mixture,and about 55 wt.%of arsenic was in tennantite.The stability of the feed and the formation of S_(2) and SO_(2)during roasting were surveyed by thermal analysis combined with mass spectrometry.Selected pure impurity sulfides were studied for reference purposes.Results indicated that arsenic was released more easily in inert atmosphere compared to air,in which oxidation products of sulfides captured the released gaseous arsenic.Kinetics analyses showed that the third-order chemical reaction and three-dimensional diffusion models were found as the most suitable mechanism functions of arsenic volatilization in inert and air atmospheres,respectively.
基金supported by the National Key Research and Development Program of China (No.2019YFC1803604)the National Natural Science Foundation of China (Nos.42007306 and 42277193).
文摘Antimony smelting activities damage the soil and vegetation surroundings while generating economic value.However,no standardizedmethods are available to diagnose the extent of soil degradation at antimony smelting sites.This study developed a standardized framework for assessing soil quality by consideringmicrobial-induced resilience and heavymetal contamination at Xikuangshan antimony smelting site.The soil resilience index(SRI)and soil contamination index(SCI)were calculated byMinimum Data Set and geo-accumulation model,respectively.After standardized by a multi-criteria quantitative procedure of modified Nemerow’s pollution index(NPI),the integrated assessment of soil quality index(SQI),which is the minimumof SRINPI and SCINPI,was achieved.The results showed that Sb and As were the prominent metal(loid)pollutants,and significant correlations between SQI and SRI indicated that the poor soil quality was mainly caused by the low level of soil resilience.The primary limiting factors of SRI were Fungi in high andmiddle contaminated areas,and Skermanella in low contaminated area,suggesting that the weak soil resilience was caused by low specific microbial abundances.Microbial regulation and phytoremediation are greatly required to improve the soil quality at antimony smelting sites from the perspectives of pollution control and resilience improvement.This study improves our understanding of ecological effects of antimony smelting sites and provides a theoretical basis for ecological restoration and sustainable development of mining areas.
文摘Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.
基金Project supported by the Science and Engineering Research Board of India(SRG/2020/002096)。
文摘Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs production and have high recycling value.In this study,smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe_(2)O_(3).This separates REEs into a slag phase from an iron-rich metallic phase.B_(2)O_(3) was also added to the system as a flux to lower the slag melting temperature.This minimizes REEs loss to the metallic phase and allows a more efficient phase separation.The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB(NdCeFeB)magnets.At 1350℃and for 1 h,the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe_(2)O_(3) and 40 wt%of B_(2)O_(3).Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX)analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron.After the selective removal of iron into the metallic phase,REEs are recovered from the slag phase through an acid leaching process allowing>99%of REEs recovery.Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique.The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.
基金supported by the National Key R&D Program of China(No.2021YFC2901200)National Natural Science Foundation of China(Nos.52174383 and 52374412)Liaoning Provincial Natural Science Foundation of China(No.2022-YQ-09).
文摘To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction reaction process of the Fe-Si bath and the migration behavior of valuable elements in the solidification and crystallization process of silicothermic reduction tailings were investigated,and a treatment method for efficiently separating and enriching REE,Nb and Ti was explored.Thermodynamic analysis indicated that at 1600℃,with a 6 wt.%addition of Si as the reducing agent,the niobium oxide in the REE-Nb-Ti-containing slag could be selectively reduced to metallic Nb.In the Fe-Si bath reduction process,the Nb mass fraction in the metal phase increased with prolonged reaction time,peaking at 2.77%,while the Ti mass fraction consistently stayed below 0.12%.Lowering the w(CaO)/w(SiO_(2))enhanced the migration of Nb from slag to metal phase and reduced the Ti impurities.During solidification and crystallization,a significant quantity of perovskite precipitated from reduction tailings,with the REE dissolving into this perovskite.By adjusting the w(CaO)/w(SiO_(2))in tailings to 1.2-1.9 and maintaining a temperature of 1100℃for 4 h,the perovskite area fraction in the final slag could exceed 37%.Finally,a method was proposed to separate and enrich valuable elements in REE-Nb-Ti-containing slags via Fe-Si bath smelting reduction and crystallization control.
基金supported by the National Key Research and Development Project(Nos.2019YFC1804503 and 2019YFC1804504)the National Natural Science Foundation of China(No.41731279)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032).
文摘Non-ferrous metal smelting poses significant risks to public health.Specifically,the copper smelting process releases arsenic,a semi-volatile metalloid,which poses an emerging exposure risk to both workers and nearby residents.To comprehensively understand the internal exposure risks of metal(loid)s from copper smelting,we explored eighteen metal(loid)s and arsenic metabolites in the urine of both occupational and non-occupational populations using inductively coupled plasma mass spectrometry with high-performance liquid chromatography and compared their health risks.Results showed that zinc and copper(485.38 and 14.00μg/L),and arsenic,lead,cadmium,vanadium,tin and antimony(46.80,6.82,2.17,0.40,0.44 and 0.23μg/L,respectively)in workers(n=179)were significantly higher compared to controls(n=168),while Zinc,tin and antimony(412.10,0.51 and 0.15μg/L,respectively)of residents were significantly higher than controls.Additionally,workers had a higher monomethyl arsenic percentage(MMA%),showing lower arsenic methylation capacity.Source appointment analysis identified arsenic,lead,cadmium,antimony,tin and thallium as co-exposure metal(loid)s from copper smelting,positively relating to the age of workers.The hazard index(HI)of workers exceeded 1.0,while residents and control were approximately at 1.0.Besides,all three populations had accumulated cancer risks exceeding 1.0×10^(-4),and arsenite(AsIII)was the main contributor to the variation of workers and residents.Furthermore,residents living closer to the smelting plant had higher health risks.This study reveals arsenic exposure metabolites and multiple metals as emerging contaminants for copper smelting exposure populations,providing valuable insights for pollution control in non-ferrous metal smelting.
基金the financial support from China Postdoctoral Science Foundation(2024M750177)National Natural Science Foundation of China(52474345)and Science and Technology Major Project of WuHan(2023020302020572).
文摘The properties of direct reduced iron(DRI)smelting slag are important in the DRI melting process for molten iron production to ensure the slag-iron separation and quality of molten iron.The influence of binary basicity on the viscosity and sulfide capacity of CaO-SiO_(2)-MgO-Al_(2)O_(3)-FeO slag was investigated by the high-temperature experiments,structural analysis and thermodynamic calculation.The viscosity of the slag decreased rapidly with an increase in basicity from 0.4 to 0.8,and this trend became slow as the basicity further increased to 1.2.For the acidic slag with basicity of 0.4 and 0.6,the viscosity at 1500℃ was higher than 0.6 Pa s,which was harmful for the fluidity of slag melt.The slags with basicity of 0.8,1.0 and 1.2 at 1500℃ showed the low viscosity of less than 0.6 Pa s.For the basic slag with basicity of 1.0 and 1.2,the rapid precipitation of melilite led to the abrupt increase behavior of the viscosity,and the acidic slag showed the gentle temperature-viscosity curves.The Raman analysis revealed that the conversion from Q^(3) to Q^(2),Q^(1) and Q^(0) mainly occurred with the basicity increasing from 0.4 to 0.8,and the conversion from Q^(2) to Q^(1) and Q^(0) was dominant with further increase in basicity to 1.2,decreasing the degree of polymerization.The sulfide capacity was improved with the increasing basicity due to the increase in O^(2-)ions,and CaS could be formed dominantly for S^(2-)stabilization in present slag.The sulfur partition ratio was derived from sulfide capacity,and the values of sulfur partition ratio at basicity of 0.4 and 0.6 were much smaller than those at basicity of 0.8,1.0 and 1.2,indicating a weak desulfurization ability of the slag with a low basicity.
文摘Stainless steel,known for its exceptional properties and diverse applications,conventionally requires a multistage process that generates considerable CO_(2) emissions by using fossil-based carbon reductants.This study investigated hydrogen plasma smelting reduction as a novel,sustainable,and efficient method for producing stainless steel directly from lateritic nickel and chromite ores.The research aimed to examine the effect of ore proportion on AISI 300 series stainless steel production and assess the reduction process over time through thermochemical calculations and experimental studies.Results showed that increasing the proportion of chromite ore in the feed raises Cr content and reduces Ni content in metals while increasing Cr_(2)O_(3) and Al_(2)O_(3) content in oxides.A briquette comprising 30wt%chromite ore and 70wt%calcined nickel ore yields better results for AISI 300 stainless steel,with Fe,Cr,Ni,and Si content of 62.95wt%,19.37wt%,11.83wt%,and 0.72wt%,respectively,after 180 s of hydrogen plasma exposure.Nearly all NiO compounds are converted into Ni after 60 s of smelting reduction,whereas FeO compounds are almost fully converted into Fe after 120 s of smelting reduction.AISI 300 series stainless steel is successfully produced after 120 s of reduction,achieving Fe,Cr,Ni,and Si content of 64.36wt%,21.92wt%,10.08wt%,and 0.61wt%,respectively.Process optimization remains promising because the Cr_(2)O_(3) content in the slag is still relatively high at 15.52wt%.This ultrafast and direct production method holds considerable potential to transform stainless steel production by reducing environmental impact and enhancing process efficiency.Specifically,the method eliminates the use of an argon oxygen decarburization converter and vacuum oxygen decarburization in stainless steelmaking.
基金supports from the National Key R&D Program of China(No.2022YFC3901404)the Natural Science Foundation of Chongqing,China(No.CSTB2023NSCQ-BHX0166)the Fundamental Research Funds for the Central Universities,China(No.2023CDJXY-016)are sincerely acknowledged.
文摘The semi-molten smelting process of a mixture of saprolitic and limonitic laterite ores was systematically investigated and the effect of slag basicity was deeply analyzed.The results indicate that the slag system can be located in the liquidus region of low melting-point diopside(CaMgSi_(2)O_(6))when slag basicity is kept at 0.3 and limonitic laterite mass fraction is not less than 10%.When the reduction temperature,C/O mass ratio,limonitic laterite mass fraction and slag basicity are kept at the optimum values of 1300℃,0.86,20%and 0.3,respectively,ferronickel products with grades 6.42%Ni and 86.99%Fe are prepared.The recovery rates of Ni and Fe reach 88.60%and 72.25%,respectively.
基金supported by the National Key Research and Development Program of China(Nos.2023YFC3707704 and 2019YFC1805205)the Research Initiation Fund and the 16th Batch of Sailing Plan Project of China University of Mining and Technology(Nos.102524004 and 102524096)the key scientific research projects(No.ZMYJJB-2024-01)of First Exploration Burea,China National Administration of coal Geology.
文摘Under complicated field conditions,such as the coupled effects of freeze-thaw cycles(FTs)and acidification,the leaching behavior of potentially toxic element(PTEs)from indigenous Zn smelting slags(ZSS)was intricately connected to the mineralogy(e.g.,the composition,assemblage,microstructure of mineral particles).In this study,FTs tests were carried out to explore the interactions between PTEs release and ZSSmineralogy.Subsequently,advanced characterization techniqueswere adopted to quantify the mineralogy andmicrostructure of ZSS.The results indicated that ZSS were mainly composed of silicate minerals(e.g.,quartz,biotite and chlorite)and secondary Fe(III)oxyhydroxides(e.g.,magnetite and limonite),accounting for 67.48% and 24.23%,respectively.The occurrence mode analysis revealed that 81.95%of As,21.31%of Pb and 7.77% of Zn were hosted in limonite.About 37.89%,59.34% and 34.50% of Cd,Pb and Zn were associated with carbonate bound fractions.Under FTs interacting with different pH conditions,the leaching concentrations of As,Cd,Cu,Pb and Zn did not significantly increase with the increase in FTs and pH.The microstructure damage of mineral particles in ZSS with the higher porosity was caused by both FTs and proton corrosion.More importantly,the geochemical modeling results suggested that the precipitation of hematite and magnetite,as well as the dissolution of arsenolite,might have little impacts on PTEs release under FTs and FTs with acidification.This work would provide a deeper understanding of PTEs release from smelting waste slags under complex physicochemical interactions.
基金support from the National Key R&D Program of China(Nos.2023YFC3903900,2023YFC3903904)the National Natural Science Foundation of China(Nos.52274343,52174329).
文摘The melting and separation behavior of vanadium-titanium magnetite pellets directed at an efficient extraction of vanadium and titanium was systematically investigated.Applying FactSage simulations and experiments,the smelting separation of three pre-reduced pellets from different regions was analyzed.The simulations demonstrate that FeTi2O5 is converted to TiC at low temperatures,necessitating suppression of this step.Experiments under optimized conditions(1590-1690°C,20-25 min,2%coke,basicity 0.4-0.6,and 3.0%-6.0%MgO)yield iron grade of 92.35%-95.06%,titanium grade of 34.37%-39.89%,and vanadium grade of 0.56%-1.52%,with recoveries of 99.52%-99.60%,94.08%-98.96%,and 92.63%-94.38%for iron,titanium and vanadium,respectively.The titanium in the slag,primarily in the form of anosovite,is suitable for sulfuric acid-based titanium white production.An increase in basicity,MgO content,and pellet metallization serves to improve vanadium recovery in melted iron but lowers the titanium grade in the slag.The overall process effectively utilizes vanadium and titanium resources under optimized conditions.
基金supported by the National Key R&D Program of China(No.2020YFC1909203)the Hunan Provincial Innovation Project,China(No.CX20230213)。
文摘A process for treating cyanide tailings was proposed.The process essentially implicates reduction smelting which involves volatilizing silver,lead,and zinc in the cyanide tailings at high temperatures.Meanwhile,gold and copper combine with the reduced iron to form a metal phase,allowing for the simultaneous recovery of polymetallic elements.The experimental results indicate that the process works optimally with a coke powder of 7.5 wt.%,an alkalinity of 1.0,a melting temperature of 1450℃,and a melting time of 60 min.Under these conditions,more than 99% of gold,77% of copper and 94% of iron are incorporated into pig iron.In the meantime,the volatilization rate of silver exceeds 90%,while lead and zinc are essentially completely volatilized.The primary component of the by-product smelting slag is akermanite,which exhibits lower leaching toxicity than the national standard and belongs to general solid waste.Additionally,taking the trapping process of iron to copper as a case study,the mechanism of iron trapping is methodically examined and divided into three processes:smelting reduction,migration capture,and condensation deposition.
基金supported by the National Key Research and Development Program of China (No.2019YFC1803604)the National Natural Science Foundation of China (No.42177392).
文摘Heavy metal(loid)s contamination is a constant issue at smelting sites.It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites.In this study,203 soil samples from 57 sites were collected in a typical lead smelting site.The findings demonstrated that there were significant Pb,Zn,Cd,and As contamination in soil samples.The spatial distribution of heavy metal(loid)s showed strong spatial heterogeneity,the contaminated soil areas of Pb,As,Cd,and Zn were 99.5%,98.9%,85.3%,and 72.4%,respectively.Pb,Cd,and As contamination of the soil reached a depth of 5 m,which migrated from the surface to deep soil layers.The leaching contents of Zn,Pb,and As decreased obviously in 3-4 m soil layer,but the leaching content of Cd was still high,which indicated the high migration of Cd.With the increase of depth,the proportion of acid soluble fraction of heavy metal(loid)s decreased,and the residual fraction increased.The acid soluble fraction of Cd accounted for a higher proportion,and As mainly existed in reducible and residual fractions in soil.According to the calculation of the migration factor,the migration of heavy metal(loid)s in soils were ordered as Cd>Zn>Pb>As.The outcomes are advantageous for risk reduction and site remediation for non-ferrous metal smelting sites.
基金funded by the National Key Research and Development Program of China(No.2019YFC1803601)the National Natural Science Foundation of China(No.42177392)the Fundamental Research Funds for the Central Universities of Central South University(No.2021zzts0122)。
文摘The lack of understanding of heavy metal speciation and solubility control mechanisms in smelting soils limits the effective pollution control.In this study smelting soils were investigated by an advanced mineralogical analysis(AMICS),leaching tests and thermodynamic modelling.The aims were to identify the partitioning and release behaviour of Pb,Zn,Cd and As.The integration of multiple techniques was necessary and displayed coherent results.In addition to the residual fraction,Pb and Zn were predominantly associated with reducible fractions,and As primarily existed as the crystalline iron oxide-bound fractions.AMICS quantitative analysis further confirmed that Fe oxyhydroxides were the common dominant phase for As,Cd,Pb and Zn.In addition,a metal arsenate(paulmooreite)was an important mineral host for Pb and As.The pH-stat leaching indicted that the release of Pb,Zn and Cd increased towards low pH values while release of As increased towards high p H values.The separate leaching schemes were associated with the geochemical behaviour under the control of minerals and were confirmed by thermodynamic modelling.PHREEQC calculations suggested that the formation of arsenate minerals(schultenite,mimetite and koritnigite)and the binding to Fe oxyhydroxides synchronously controlled the release of Pb,Zn,Cd and As.Our results emphasized the governing role of Fe oxyhydroxides and secondary insoluble minerals in natural attenuation of heavy metals,which provides a novelty strategy for the stabilization of multi-metals in smelting sites.
基金support from the National Key Research and Development Program of China(Grant No.2019YFA0705300)the National Natural Science Foundation of China(GrantNo.52004051)the Innovation Team Projectfor Key Fields of Dalian(Grant No.2019RT13).
文摘The prevention of hot cracking formation is of utmost importance in the production of the new Ni-Co based superalloys through the utilization of the electron beam smelting layered solidification technique(EBSL),as it ensures exceptional homogeneity and dependable consistency of the specimens.In contrast to previous studies that focused on minimizing the liquid film and solidification range,our methodology adopts a distinct approach.In this research,a novel methodology was employed to mitigate internal stresses through the implementation of equiaxed grain layers via an alternately reduced cooling method.This ultimately resulted in the elimination of hot cracking.To be more specific,the transition from a columnar to an equiaxed structure was observed during the layer-by-layer construction process in the fabrication of the new Ni-Co based superalloy in EBSL.The EBSL-Ni-Co superalloy,when subjected to the alternating reduction cooling method,exhibited an internal stress of 49 MPa.This value represents a significant reduction of 83.8%compared to the internal stress observed when employing the linear reduction cooling method.Additionally,the solvus temperature of theγ-γ’eutectic phases in EBSL-Ni-Co superalloys produced by the alternating reduction cooling method is significantly higher.Intriguingly,the Nth layer of the EBSL-Ni-Co based superalloys produced by EBSL simultaneously heats treated with the preceding layers.And the low melting point phase gradually dissolved back into the matrix.The implementation of an alternating reduced cooling method successfully mitigated the formation of the liquid film in theγ-γ’eutectic phase and the buildup of internal stresses in the EBSL-Ni-Co superalloy during its manufacturing process.These discoveries open up a novel preparation procedure pathway for the manufacture of crack-free superalloys with superior mechanical characteristics using EBSL.
基金the National Key Research and Development Program of China(No.2019YFC1908400)the National Natural Science Foundation of China(Nos.52174334,52374413)+3 种基金the Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects,China(Nos.20212BCJ23007,20212BCJL23052)the Jiangxi Provincial Natural Science Foundation,China(Nos.20224ACB214009,20224BAB214040)the Double Thousand Plan of Jiangxi Province,China(No.S2021GDQN2970)the Distinguished Professor Program of Jinggang Scholars in Institutions of Higher Learning of Jiangxi Province,China.
文摘The separation of halogens and recovery of heavy metals from secondary copper smelting(SCS)dust using a sulfating roasting−water leaching process were investigated.The thermodynamic analysis results confirm the feasibility of the phase transformation to metal sulfates and to gaseous HF and HCl.Under the sulfating roasting conditions of the roasting temperature of 250℃ and the sulfuric acid excess coefficient of 1.8,over 74 wt.%of F and 98 wt.%of Cl were volatilized into flue gas.Approximately 98.6 wt.%of Zn and 96.5 wt.%of Cu in the roasting product were dissolved into the leaching solution after the water leaching process,while the leaching efficiencies of Pb and Sn were only 0.12%and 0.22%,respectively.The mechanism studies indicate the pivotal effect of roasting temperature on the sulphation reactions from various metal species to metal sulfates and the salting out reactions from various metal halides to gaseous hydrogen halides.
基金financially supported from the National Key Research and Development Program of China(No.2019YFC1803601)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2023ZZTS0801)+1 种基金the Postgraduate Innovative Project of Central South University,China(No.2023XQLH068)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.QL20230054)。
文摘A general prediction model for seven heavy metals was established using the heavy metal contents of 207soil samples measured by a portable X-ray fluorescence spectrometer(XRF)and six environmental factors as model correction coefficients.The eXtreme Gradient Boosting(XGBoost)model was used to fit the relationship between the content of heavy metals and environment characteristics to evaluate the soil ecological risk of the smelting site.The results demonstrated that the generalized prediction model developed for Pb,Cd,and As was highly accurate with fitted coefficients(R^(2))values of 0.911,0.950,and 0.835,respectively.Topsoil presented the highest ecological risk,and there existed high potential ecological risk at some positions with different depths due to high mobility of Cd.Generally,the application of machine learning significantly increased the accuracy of pXRF measurements,and identified key environmental factors.The adapted potential ecological risk assessment emphasized the need to focus on Pb,Cd,and As in future site remediation efforts.
基金the Applied Basic Research Project of Yunnan Province,China(No.202301 AT070411).
文摘The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method.The essential aspects of the fluid phase(e.g.,splashing volume,dead zone of copper slag,and gas penetration depth)were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases.The results illustrated that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance,respectively.The expansion of larger ones as well as the shrinking of smaller ones combine to cause the contraction of the bubble waist.Compared to the results of the case with a fixed gas injection velocity(V_(g)=58 m/s),the splashing volume and dead zone volume of the slag under the V_(g)=58+10sin(2πt)condition are reduced by 24.9%and 23.5%,respectively,where t represents the instant time.Gas penetration depth and slag motion velocity of the latter are 1.03 and 1.31 times high-er than those of the former,respectively.
基金the support from the National Key R&D Program of China(No.2018YFC1901606).
文摘A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effect.Its modeling results were verified with theoretical correlations and experiments,and the nozzle-eroded states in practice were also involved in the analysis.Through comparison,it is confirmed that the thermal expansion effect influences the flow pattern significantly,which may lead to the backward motion of airflow and create a potential risk to production safety.Consequently,the influences of air injection velocity and furnace width on airflow behavior were investigated to provide operating and design guidance.It is found that the thin layer melt,which avoids high-rate oxygen airflow eroding nozzles,shrinks as the injection velocity increases,but safety can be guaranteed when the velocity ranges from 175 to 275 m/s.Moreover,the isoline patterns and heights of thin layers change slightly when the furnace width increases from 2.2 to 2.8 m,indicating that the furnace width shows a limited influence on production safety.
基金the Karamanoglu Mehmetbey University Scientific Research Projects(BAP)Coordinating Office for support with grant number KMU-BAP-17-M-18.
文摘This research was performed to investigate the optimization of copper recovery from copper smelting slag(CSS)with a deep eutectic solvent as a green reagent.The effect of important parameters on the leaching efficiency of copper and zinc(as well as dissolution of iron),such as leaching time,leaching temperature,solid/liquid ratio,and particle size was studied.In order to model the copper recovery,an optimization method was used.According to the chemical analysis of CSS,the slag contains 0.9%copper,3.3%zinc,and 36.7%iron.Also,it was found that the CSS is mainly composed of Fe2SiO4,Fe3O4 and SiO2.Copper-containing structures were determined as CuO and CuS.As a result of leaching experiments,80%copper and 61%zinc recoveries were obtained at 48 h,95℃,1/25 g·ml^(-1),and-33 mm.It is noted that the iron and silicon dissolution remained negligible under the selected conditions.According to the mathematical model,the highest copper leaching efficiency(up to 100%)could be under optimum working conditions as 48.5℃leaching temperature,40.1 h leaching duration,and 62.3 ml·g^(-1)solid/liquid ratio.Also,the proposed model revealed that a wide range of experimental levels can be used as leaching parameter to get desired metal leaching efficiency.
