Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low gra...Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low grades.Therefore,the effective extraction and recovery of metallic vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore.Herein,Bacillus mucilaginosus was selected as the leaching strain.The vanadium leaching rate reached 35.5%after 20 d of bioleaching under optimal operating conditions.The cumulative vanadium leaching rate in the contact group reached 35.5%,which was higher than that in the noncontact group(9.3%).The metabolites of B.mucilaginosus,such as oxalic,tartaric,citric,and malic acids,dominated in bioleaching,accounting for 73.8%of the vanadium leaching rate.Interestingly,during leaching,the presence of stone coal stimulated the expression of carbonic anhydrase in bacterial cells,and enzyme activity increased by 1.335-1.905 U.Enzyme activity positively promoted the production of metabolite organic acids,and total organic acid content increased by 39.31 mg·L^(-1),resulting in a reduction of 2.51 in the pH of the leaching system with stone coal.This effect favored the leaching of vanadium from stone coal.Atomic force microscopy illustrated that bacterial leaching exacerbated corrosion on the surface of stone coal beyond 10 nm.Our study provides a clear and promising strategy for exploring the bioleaching mechanism from the perspective of microbial enzyme activity and metabolites.展开更多
In order to provide a reliable reference for utilizing Indonesia vanadium titano-magnetite(VTM) in blast furnace(BF) economically, metallurgical properties of iron ore sinter with addition of Indonesia VTM in mixed si...In order to provide a reliable reference for utilizing Indonesia vanadium titano-magnetite(VTM) in blast furnace(BF) economically, metallurgical properties of iron ore sinter with addition of Indonesia VTM in mixed sintering materials were investigated, including low-temperature reduction degradation index(RDI), reducibility index(RI), and softening/melting properties. Additionally, influenced mechanism of Indonesia VTM on metallurgical properties of sinter was studied. It is found that adding Indonesia VTM in sintering process quickly increases the RDI of sinters, and decreases the RI from 78.02% to 68.43%. Moreover, both beginning temperature(T_4) and final temperature(TD) of softening/melting increase gradually, and cohesive zone temperature range(T_D–T_4) enlarges from 219 oC to 315 oC. As a result, the permeability of cohesive zone gets worse, which is proven by the higher maximum pressure drop(δPmax) in softening/melting experiments. It is concluded that, after comprehensively considering all metallurgical properties mentioned above, the proper proportion of Indonesia VTM in sintering process is proposed in the new raw materials conditions.展开更多
Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed ...Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H2, CO, H2O, CO2, and N2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C–H–O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C–H–O system as a reducing agent was obtained;it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H2/(H2 + CO), and decreasing H2O, CO2, and N2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.展开更多
The reduction of vanadium titano-magnetite pellets by H_2-CO at temperatures from 850 to 1050°C was investigated in this paper. The influences of pre-oxidation treatment, reduction temperature, and V_(H_2)/(V_...The reduction of vanadium titano-magnetite pellets by H_2-CO at temperatures from 850 to 1050°C was investigated in this paper. The influences of pre-oxidation treatment, reduction temperature, and V_(H_2)/(V_(H_2) + VCO) on the metallization degree were studied. The results showed that pre-oxidation played a substantial role in the reduction of vanadium titano-magnetite pellets. During the reduction process, the metallization degree increased with increasing temperature and increasing V_(H_2) /(V_(H_2) + VCO). The phase transformation of pre-oxidized vanadium titano-magnetite pellets during the reduction process under an H_2 atmosphere and a CO atmosphere was discussed, and the reduced samples were analyzed by scanning electron microscopy(SEM) in conjunction with back scatter electron(BSE) imaging. The results show that the difference in thermodynamic reducing ability between H_2 and CO is not the only factor that leads to differences in the reduction results obtained using different atmospheres. Some of Fe_(3-x)Ti_xO_4 cannot be reduced under a CO atmosphere because of the densification of particles' structure and because of the enrichment of Mg in unreacted cores. By contrast, a loose structure of particles was obtained when the pellets were reduced under an H_2 atmosphere and this structure decreased the resistance to gas diffusion. Moreover, the phenomenon of Mg enrichment in unreacted cores disappeared during H_2 reduction. Both the lower resistance to gas diffusion and the lack of Mg enrichment facilitated the reduction of vanadium titano-magnetite.展开更多
The effect of microwave treatment on the grinding and dissociation characteristics of vanadium titano-magnetite(VTM) ore were investigated using scanning electron microscopy(SEM), nitrogen absorption measurements, par...The effect of microwave treatment on the grinding and dissociation characteristics of vanadium titano-magnetite(VTM) ore were investigated using scanning electron microscopy(SEM), nitrogen absorption measurements, particle size distribution measurements, X-ray diffraction(XRD) analysis, Fourier transform infrared(FT-IR) spectroscopic analysis, and magnetic separation. SEM analysis showed that microfractures appeared in the microwave-treated VTM, which is attributed to the microwaves' selective heating characteristic and the differential expansion between minerals and gangues. Nitrogen absorption showed that the microfractures were more pronounced when the microwave heating time was increased. Particle size distribution analysis showed that microwave treatment could improve the grindability of the VTM, thus increasing the weight percent of the fine-ground product. The increase in grindability was more significant with prolonged heating time. Moreover, the particle size distribution of the fine-ground product changed only slightly after the microwave treatment. XRD analysis showed that the crystallinity of the microwave-treated VTM increased with increasing microwave heating time. The magnetic separation tests revealed that the separation efficiency increased as a result of the intergranular fractures generated by microwave treatment. The Fe grade of the magnetic fraction of microwave-treated VTM was 1.72% higher than that of the raw ore. We concluded that the microwave treatment was beneficial, especially for the mineral processing characteristics.展开更多
There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the wate...There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the water quality characteristics and pollution degree are relatively weak.This contribution was organized to investigate the surface water quality by general parameters,including TDS,Eh,pH,DO,TOC,COD,and EC,in the vanadium ore belt(Yinhua River basin).Major ions were determined to detect the water type and natural chemical weathering,while trace elements were used to illustrate their geochemical characteristics and ecological risk assessment of heavy metals.The study found that the surface water was weakly alkaline and mainly dominated from normal to pool grade.The particle size with1000–10,000 nm of suspended particles was the main carrier of organic matter.The concentration of HCO_(3)^(-)and SO_(4)^(2-)in the anions and Ca^(2+)and Mg^(2+)ions in the cations were relatively high,and the water type was Ca-Mg-HCO_(3)-SO_(4) type.Rock weathering had a great influence on surface water,and the weathering products were mainly silicate and carbonate.Compared with the Type river,the contents of V elements showed an obvious positive anomaly,which may be affected by mining activities of vanadium ore and the annual leaching of the tailings pond.As and Cd in the surface water was polluted seriously.The integrated pollution index suggested that the surface water pollution was serious,and the main stream was more serious with the increasing tailings ponds.展开更多
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when...The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 moUL H2SO4 at 90℃ for 2 h. After the sample is roasted at 900℃ for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the Content of V(V) increases with the rise of roasting temperature from 600 to 900℃, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000℃. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.展开更多
To achieve high efficiency utilization of high-chromium vanadium-titanium magnetite (V-Ti-Cr) fines, an investigation of V Ti42r fines was conducted using a sinter pot. The chemical composition, particle parameters,...To achieve high efficiency utilization of high-chromium vanadium-titanium magnetite (V-Ti-Cr) fines, an investigation of V Ti42r fines was conducted using a sinter pot. The chemical composition, particle parameters, and granulation of V-Ti-Cr mixtures were analyzed, and the effects of sintering parameters on the sintering behaviors were investigated. The results indicated that the optimum quicklime dosage, mixture moisture, wetting time, and granulation time for V-Ti-Cr fines are 5wt%, 7.5wt%, 10 min, and 5-8 min, respectively. Meanwhile, the vertical sintering speed, yield, tumbler strength, and productivity gains were shown to be 21.28 mm/min, 60.50wt% , 58.26wt%, and 1.36 t·m^-2·h^-1, respectively. Furthermore, the consolidation mechanism of V-Ti-Cr fines was clarified, revealing that the consolidation of a V-Ti-Cr sinter requires an approximately 14vo1% calcium ferrite liquid-state, an approximately 15vo1% silicate liq- uid-state, a solid-state reaction, and the recrystallization of magnetite. Compared to an ordinary sinter, calcium ferrite content in a V-Ti-Cr sinter is lower, while the perovskite content is higher, possibly resulting in unsatisfactory sinter outcomes.展开更多
The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms...The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMS)experiments were compared.At respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe recovery.Compared with the goethitic ore,the titanomagnetite ore responded better to MW heating.The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide phases.Finally,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.展开更多
Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences t...Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences the bonding degree, which ultimately determines the sinter strength. Infiltration tests were conducted using micro-sinter equipment. The infiltration area index of original liquid(IAO), infiltration volume index of secondary liquid(IVS), and sinter body bonding strength(SBS) were proposed to study the melt infiltration behavior. The results show that the IVS first increases and then decreases with increasing TiO2 content in adhering fines, whereas the IAO exhibits the opposite behavior. Compared with the original liquid, the secondary liquid shows lower porosity, smaller pores, and more uniform distribution. The SBS increases first and then decreases with increasing IAO and TiO2 content, and reaches a maximum when the IAO and TiO2 contents are approximately 0.5 and 2.0wt%, respectively. The SBS first increases and then tends to be stable with increasing IVS. The TiO2 content is suggested to be controlled to approximately 2.0wt% in low-titanium ore sintering.展开更多
Currently there have been formed industrial uranium deposits in Kyzylkum province that refer to three types of formations—exogenetic uranium formation in the sediments of Mesozoic-Cenozoic cover,endogenic molybdenum-...Currently there have been formed industrial uranium deposits in Kyzylkum province that refer to three types of formations—exogenetic uranium formation in the sediments of Mesozoic-Cenozoic cover,endogenic molybdenum-uranium formation and polygenic molybdenum-uranium-vanadium formation in carbon-siliceous shale formations ("black-shale"type).Carbon-siliceous shales are展开更多
Experiments were carried out by adding CaF2 and NaF as catalysts in an Ar atmosphere to study the isothermal reduction kinetics of vanadium titano-magnetite carbon composite pellets under high temperature in the range...Experiments were carried out by adding CaF2 and NaF as catalysts in an Ar atmosphere to study the isothermal reduction kinetics of vanadium titano-magnetite carbon composite pellets under high temperature in the range from 1 473 to 1 673 K. The scanning electron microscope (SEM) was used to characterize the microstructure of product. By analyzing reduction mechanism, it was found that the rate controlling step was gas diffusion, and the activation energy was 178.39 kJ/mol without adding any catalysts. Adding CaF2 or NaF of 3% to vanadium titano-magnetite carbon composite pellets can decrease the apparent activation energy of reduction, and the decrease extent was 14.95 and 15.79 kJ/mol, respectively. In addition, temperature was an important factor influencing on reaction rate.展开更多
The vanadium titano-magnetite (VTM) iron ore fines of 110--150/xm in diameter were reduced in a trans- parent quartz fluidized bed by 70 %CO-30 % H2 (volume fraction) mixtures. MgO powders served as coating agent ...The vanadium titano-magnetite (VTM) iron ore fines of 110--150/xm in diameter were reduced in a trans- parent quartz fluidized bed by 70 %CO-30 % H2 (volume fraction) mixtures. MgO powders served as coating agent to solve sticking problem. Two coating methods were introduced in this experiment: high temperature injection method and briquetting→oxidizing roast→crushing method. According to the experimental results, the minimum effective coating amount of MgO was 0. 1 mass%. The metallization ratio (MR) of the product rose from around 58% to above 90% with the above treatments. To investigate the sticking mechanism of fine ore, the morphology evolution was in- vestigated. Instead of iron whiskers, an interlaced fibrous porous surface formed. The ulvospinel (2FeO : TiO2 ) in VTM is more difficult to be reduced than FeO according to thermodynamic calculation. XRD results showed that MgO diffused into Fe203 lattice before forming pleonaste (MgO · Fe2O3 ) during oxidizing roast at 1273 K. The melting point of the pleonaste is 1986 K and that made contribution to prevent the sticking problem.展开更多
The large quantity of sediment produced in the hearth during vanadium titano-magnetite smelting in a blast furnace(BF) affects the stability of the blast furnace operation. Testing and analysis of the sediment in th...The large quantity of sediment produced in the hearth during vanadium titano-magnetite smelting in a blast furnace(BF) affects the stability of the blast furnace operation. Testing and analysis of the sediment in the hearth of Chengde Iron and Steel Company?s BF No.7 revealed that it was mainly concentrated in the location below the tuyere and above the iron notch. Notably, some of the bonding material(sediment) consisted of greater than 50% pig iron, and the pig iron distributed in the slag was granular. It is proposed that a large quantity of Ti C and Ti(C,N) are deposited on the surface of the pig iron. These high melting point materials mix with iron drops, preventing the slag from flowing freely, thus leading to the formation of bonding materials. In addition, the viscosity and melting temperature of the slag in the tuyere areas fluctuate greatly, and thus the properties of the slag are unstable. Moreover, the slag contains large quantities of carbon, which results in the reduction of Ti O2. The resultant precipitation of Ti is followed by the formation of Ti C in the slag, which also leads to an increase in the viscosity of the slag and difficulty in achieving separation of the slag-iron. In fact, all of these factors interact with each other, and as a result, sediment is formed when the operating conditions in the hearth fluctuate.展开更多
The Obrochishte deposit located in the Republic of Bulgaria has considerable reserves of relatively poor carbonate manganese ore. At the same time, in the country there are operative outputs for the production of sulp...The Obrochishte deposit located in the Republic of Bulgaria has considerable reserves of relatively poor carbonate manganese ore. At the same time, in the country there are operative outputs for the production of sulphuric acid where vanadium catalyst is deactivated and discharged, polluting the environment. The utilization of these materials requires their consolidation to proper sizes with regard to the next processing, as the most suitable method for joint consolidation is agglomeration. The present work explores the preliminary calculations for obtaining agglomerate and obtaining an alloy with high and low carbon content, through carbothermic and aluminothermic agglomerate reduction.展开更多
High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the enviro...High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the environment and affect product quality due to heavy metals in the wastewater.The wastewater is usually treated by lime neutralization,but valuable metals(especially V and Mn)cannot be recovered.In this study,an efficient and environmentally friendly method was developed to recover valuable metals by using a solvent extraction-precipitation process.In the solvent extraction process,98.15%of vanadium was recovered,and the V2Os product,with a purity of 98.60%,was obtained under optimal conditions.For the precipitation process,91.05%of manganese was recovered as MnCO3 which meets the III grade standard of HG/T 2836-2011.Thermodynamic simulation analysis indicated that MnCO3 was selectively precipitated at pH 6.5 while Mg and Ca could hardly be precipitated.The results of X-ray diffraction and scanning electron microscopy demonstrated that the obtained V2Os and MnCO3 displayed a good degree of crystallinity.The treated wastewater can be returned for leaching,and resources(V and Mn)in the wastewater were utilized efficiently in an environmentally friendly way.Therefore,this study provides a novel method for the coextraction of V and Mn from HMVW.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(No.51874018)the Open Foundation of State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2022-07).
文摘Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low grades.Therefore,the effective extraction and recovery of metallic vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore.Herein,Bacillus mucilaginosus was selected as the leaching strain.The vanadium leaching rate reached 35.5%after 20 d of bioleaching under optimal operating conditions.The cumulative vanadium leaching rate in the contact group reached 35.5%,which was higher than that in the noncontact group(9.3%).The metabolites of B.mucilaginosus,such as oxalic,tartaric,citric,and malic acids,dominated in bioleaching,accounting for 73.8%of the vanadium leaching rate.Interestingly,during leaching,the presence of stone coal stimulated the expression of carbonic anhydrase in bacterial cells,and enzyme activity increased by 1.335-1.905 U.Enzyme activity positively promoted the production of metabolite organic acids,and total organic acid content increased by 39.31 mg·L^(-1),resulting in a reduction of 2.51 in the pH of the leaching system with stone coal.This effect favored the leaching of vanadium from stone coal.Atomic force microscopy illustrated that bacterial leaching exacerbated corrosion on the surface of stone coal beyond 10 nm.Our study provides a clear and promising strategy for exploring the bioleaching mechanism from the perspective of microbial enzyme activity and metabolites.
基金Projects(51604069,51604049,U1508213) supported by the National Natural Science Foundation of ChinaProject(N162504004) supported by the Fundamental Research Funds for the Central Universities,ChinaProjects(2017YFB0603800,2017YFB0603801) supported by the National Key R&D Program of China
文摘In order to provide a reliable reference for utilizing Indonesia vanadium titano-magnetite(VTM) in blast furnace(BF) economically, metallurgical properties of iron ore sinter with addition of Indonesia VTM in mixed sintering materials were investigated, including low-temperature reduction degradation index(RDI), reducibility index(RI), and softening/melting properties. Additionally, influenced mechanism of Indonesia VTM on metallurgical properties of sinter was studied. It is found that adding Indonesia VTM in sintering process quickly increases the RDI of sinters, and decreases the RI from 78.02% to 68.43%. Moreover, both beginning temperature(T_4) and final temperature(TD) of softening/melting increase gradually, and cohesive zone temperature range(T_D–T_4) enlarges from 219 oC to 315 oC. As a result, the permeability of cohesive zone gets worse, which is proven by the higher maximum pressure drop(δPmax) in softening/melting experiments. It is concluded that, after comprehensively considering all metallurgical properties mentioned above, the proper proportion of Indonesia VTM in sintering process is proposed in the new raw materials conditions.
基金financially supported by the Ministry of Land and Resources Public Welfare Industry Research Project, China (No. 201511062-02)
文摘Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H2, CO, H2O, CO2, and N2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C–H–O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C–H–O system as a reducing agent was obtained;it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H2/(H2 + CO), and decreasing H2O, CO2, and N2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.
基金financially supported by the Fundamental Research Funds for the Central Universities(2014zzts273)
文摘The reduction of vanadium titano-magnetite pellets by H_2-CO at temperatures from 850 to 1050°C was investigated in this paper. The influences of pre-oxidation treatment, reduction temperature, and V_(H_2)/(V_(H_2) + VCO) on the metallization degree were studied. The results showed that pre-oxidation played a substantial role in the reduction of vanadium titano-magnetite pellets. During the reduction process, the metallization degree increased with increasing temperature and increasing V_(H_2) /(V_(H_2) + VCO). The phase transformation of pre-oxidized vanadium titano-magnetite pellets during the reduction process under an H_2 atmosphere and a CO atmosphere was discussed, and the reduced samples were analyzed by scanning electron microscopy(SEM) in conjunction with back scatter electron(BSE) imaging. The results show that the difference in thermodynamic reducing ability between H_2 and CO is not the only factor that leads to differences in the reduction results obtained using different atmospheres. Some of Fe_(3-x)Ti_xO_4 cannot be reduced under a CO atmosphere because of the densification of particles' structure and because of the enrichment of Mg in unreacted cores. By contrast, a loose structure of particles was obtained when the pellets were reduced under an H_2 atmosphere and this structure decreased the resistance to gas diffusion. Moreover, the phenomenon of Mg enrichment in unreacted cores disappeared during H_2 reduction. Both the lower resistance to gas diffusion and the lack of Mg enrichment facilitated the reduction of vanadium titano-magnetite.
基金financially supported by the National Natural Science Foundation of China (Nos. 51574082 and 51874077)the Fundamental Research Funds for the Central University of China (Nos. N150202001 and N172507012)
文摘The effect of microwave treatment on the grinding and dissociation characteristics of vanadium titano-magnetite(VTM) ore were investigated using scanning electron microscopy(SEM), nitrogen absorption measurements, particle size distribution measurements, X-ray diffraction(XRD) analysis, Fourier transform infrared(FT-IR) spectroscopic analysis, and magnetic separation. SEM analysis showed that microfractures appeared in the microwave-treated VTM, which is attributed to the microwaves' selective heating characteristic and the differential expansion between minerals and gangues. Nitrogen absorption showed that the microfractures were more pronounced when the microwave heating time was increased. Particle size distribution analysis showed that microwave treatment could improve the grindability of the VTM, thus increasing the weight percent of the fine-ground product. The increase in grindability was more significant with prolonged heating time. Moreover, the particle size distribution of the fine-ground product changed only slightly after the microwave treatment. XRD analysis showed that the crystallinity of the microwave-treated VTM increased with increasing microwave heating time. The magnetic separation tests revealed that the separation efficiency increased as a result of the intergranular fractures generated by microwave treatment. The Fe grade of the magnetic fraction of microwave-treated VTM was 1.72% higher than that of the raw ore. We concluded that the microwave treatment was beneficial, especially for the mineral processing characteristics.
基金supported by National Natural Science Foundation of China(No.4210021463)Natural Science Basic Research Program of Shaanxi Province(No.2020JQ-744)+2 种基金China Postdoctoral Science Foundation(No.2020M673443)Shaanxi Provincial Education Department general special project(No.21JK0775)Public Welfare Geology Project of Shaanxi Province(No.201907)。
文摘There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the water quality characteristics and pollution degree are relatively weak.This contribution was organized to investigate the surface water quality by general parameters,including TDS,Eh,pH,DO,TOC,COD,and EC,in the vanadium ore belt(Yinhua River basin).Major ions were determined to detect the water type and natural chemical weathering,while trace elements were used to illustrate their geochemical characteristics and ecological risk assessment of heavy metals.The study found that the surface water was weakly alkaline and mainly dominated from normal to pool grade.The particle size with1000–10,000 nm of suspended particles was the main carrier of organic matter.The concentration of HCO_(3)^(-)and SO_(4)^(2-)in the anions and Ca^(2+)and Mg^(2+)ions in the cations were relatively high,and the water type was Ca-Mg-HCO_(3)-SO_(4) type.Rock weathering had a great influence on surface water,and the weathering products were mainly silicate and carbonate.Compared with the Type river,the contents of V elements showed an obvious positive anomaly,which may be affected by mining activities of vanadium ore and the annual leaching of the tailings pond.As and Cd in the surface water was polluted seriously.The integrated pollution index suggested that the surface water pollution was serious,and the main stream was more serious with the increasing tailings ponds.
基金financially supported by the National Key Technologies R&D Program of China(Nos.2011BAB05B01 and 2011BAB05B04)the Exclusive Research Fund of Environmental Protection for the Commonweal of China(No.201009013)
文摘The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 moUL H2SO4 at 90℃ for 2 h. After the sample is roasted at 900℃ for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the Content of V(V) increases with the rise of roasting temperature from 600 to 900℃, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000℃. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.
基金the National High Technology Research and Development Program of China (Nos. 2012AA062302 and 2012AA062304)the Program of the National Natural Science Foundation of China (Nos. 51090384 and 51174051)The International Cooperation of the Ministry of Science and Technology of China (No. 2012DFR60210)
文摘To achieve high efficiency utilization of high-chromium vanadium-titanium magnetite (V-Ti-Cr) fines, an investigation of V Ti42r fines was conducted using a sinter pot. The chemical composition, particle parameters, and granulation of V-Ti-Cr mixtures were analyzed, and the effects of sintering parameters on the sintering behaviors were investigated. The results indicated that the optimum quicklime dosage, mixture moisture, wetting time, and granulation time for V-Ti-Cr fines are 5wt%, 7.5wt%, 10 min, and 5-8 min, respectively. Meanwhile, the vertical sintering speed, yield, tumbler strength, and productivity gains were shown to be 21.28 mm/min, 60.50wt% , 58.26wt%, and 1.36 t·m^-2·h^-1, respectively. Furthermore, the consolidation mechanism of V-Ti-Cr fines was clarified, revealing that the consolidation of a V-Ti-Cr sinter requires an approximately 14vo1% calcium ferrite liquid-state, an approximately 15vo1% silicate liq- uid-state, a solid-state reaction, and the recrystallization of magnetite. Compared to an ordinary sinter, calcium ferrite content in a V-Ti-Cr sinter is lower, while the perovskite content is higher, possibly resulting in unsatisfactory sinter outcomes.
基金The authors are thankful to the Director,CSIR-IMMT,Bhubaneswar for his permission to publish this paper and the Ministry of Steel,Government of India,for their financial support(F.No.11(12)/GBS/2014-TW).
文摘The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMS)experiments were compared.At respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe recovery.Compared with the goethitic ore,the titanomagnetite ore responded better to MW heating.The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide phases.Finally,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.
基金financially supported by the Major State Basic Research Development Program of China (No. 2012CB720401)the Natural Science Foundation of China and Baosteel (No. 51134008)the National Natural Science Foundation of China (No. U1260202)
文摘Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences the bonding degree, which ultimately determines the sinter strength. Infiltration tests were conducted using micro-sinter equipment. The infiltration area index of original liquid(IAO), infiltration volume index of secondary liquid(IVS), and sinter body bonding strength(SBS) were proposed to study the melt infiltration behavior. The results show that the IVS first increases and then decreases with increasing TiO2 content in adhering fines, whereas the IAO exhibits the opposite behavior. Compared with the original liquid, the secondary liquid shows lower porosity, smaller pores, and more uniform distribution. The SBS increases first and then decreases with increasing IAO and TiO2 content, and reaches a maximum when the IAO and TiO2 contents are approximately 0.5 and 2.0wt%, respectively. The SBS first increases and then tends to be stable with increasing IVS. The TiO2 content is suggested to be controlled to approximately 2.0wt% in low-titanium ore sintering.
文摘Currently there have been formed industrial uranium deposits in Kyzylkum province that refer to three types of formations—exogenetic uranium formation in the sediments of Mesozoic-Cenozoic cover,endogenic molybdenum-uranium formation and polygenic molybdenum-uranium-vanadium formation in carbon-siliceous shale formations ("black-shale"type).Carbon-siliceous shales are
基金Item Sponsored by National Key Technology Research and Development Program of China(2008BAB32B05)
文摘Experiments were carried out by adding CaF2 and NaF as catalysts in an Ar atmosphere to study the isothermal reduction kinetics of vanadium titano-magnetite carbon composite pellets under high temperature in the range from 1 473 to 1 673 K. The scanning electron microscope (SEM) was used to characterize the microstructure of product. By analyzing reduction mechanism, it was found that the rate controlling step was gas diffusion, and the activation energy was 178.39 kJ/mol without adding any catalysts. Adding CaF2 or NaF of 3% to vanadium titano-magnetite carbon composite pellets can decrease the apparent activation energy of reduction, and the decrease extent was 14.95 and 15.79 kJ/mol, respectively. In addition, temperature was an important factor influencing on reaction rate.
基金Sponsored by National Natural Science Foundation of China(51234001)National Basic Research Program of China(2012CB720401)
文摘The vanadium titano-magnetite (VTM) iron ore fines of 110--150/xm in diameter were reduced in a trans- parent quartz fluidized bed by 70 %CO-30 % H2 (volume fraction) mixtures. MgO powders served as coating agent to solve sticking problem. Two coating methods were introduced in this experiment: high temperature injection method and briquetting→oxidizing roast→crushing method. According to the experimental results, the minimum effective coating amount of MgO was 0. 1 mass%. The metallization ratio (MR) of the product rose from around 58% to above 90% with the above treatments. To investigate the sticking mechanism of fine ore, the morphology evolution was in- vestigated. Instead of iron whiskers, an interlaced fibrous porous surface formed. The ulvospinel (2FeO : TiO2 ) in VTM is more difficult to be reduced than FeO according to thermodynamic calculation. XRD results showed that MgO diffused into Fe203 lattice before forming pleonaste (MgO · Fe2O3 ) during oxidizing roast at 1273 K. The melting point of the pleonaste is 1986 K and that made contribution to prevent the sticking problem.
基金Item Sponsored by National Natural Science Foundation of China(U1360205)
文摘The large quantity of sediment produced in the hearth during vanadium titano-magnetite smelting in a blast furnace(BF) affects the stability of the blast furnace operation. Testing and analysis of the sediment in the hearth of Chengde Iron and Steel Company?s BF No.7 revealed that it was mainly concentrated in the location below the tuyere and above the iron notch. Notably, some of the bonding material(sediment) consisted of greater than 50% pig iron, and the pig iron distributed in the slag was granular. It is proposed that a large quantity of Ti C and Ti(C,N) are deposited on the surface of the pig iron. These high melting point materials mix with iron drops, preventing the slag from flowing freely, thus leading to the formation of bonding materials. In addition, the viscosity and melting temperature of the slag in the tuyere areas fluctuate greatly, and thus the properties of the slag are unstable. Moreover, the slag contains large quantities of carbon, which results in the reduction of Ti O2. The resultant precipitation of Ti is followed by the formation of Ti C in the slag, which also leads to an increase in the viscosity of the slag and difficulty in achieving separation of the slag-iron. In fact, all of these factors interact with each other, and as a result, sediment is formed when the operating conditions in the hearth fluctuate.
文摘The Obrochishte deposit located in the Republic of Bulgaria has considerable reserves of relatively poor carbonate manganese ore. At the same time, in the country there are operative outputs for the production of sulphuric acid where vanadium catalyst is deactivated and discharged, polluting the environment. The utilization of these materials requires their consolidation to proper sizes with regard to the next processing, as the most suitable method for joint consolidation is agglomeration. The present work explores the preliminary calculations for obtaining agglomerate and obtaining an alloy with high and low carbon content, through carbothermic and aluminothermic agglomerate reduction.
基金This study was financially supported by Project of National Natural Science Foundation of China(Grant Nos.51774215,51474162,and 51774216)Project of Hubei Province Science Foundation of China(No.2018CFA068).
文摘High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the environment and affect product quality due to heavy metals in the wastewater.The wastewater is usually treated by lime neutralization,but valuable metals(especially V and Mn)cannot be recovered.In this study,an efficient and environmentally friendly method was developed to recover valuable metals by using a solvent extraction-precipitation process.In the solvent extraction process,98.15%of vanadium was recovered,and the V2Os product,with a purity of 98.60%,was obtained under optimal conditions.For the precipitation process,91.05%of manganese was recovered as MnCO3 which meets the III grade standard of HG/T 2836-2011.Thermodynamic simulation analysis indicated that MnCO3 was selectively precipitated at pH 6.5 while Mg and Ca could hardly be precipitated.The results of X-ray diffraction and scanning electron microscopy demonstrated that the obtained V2Os and MnCO3 displayed a good degree of crystallinity.The treated wastewater can be returned for leaching,and resources(V and Mn)in the wastewater were utilized efficiently in an environmentally friendly way.Therefore,this study provides a novel method for the coextraction of V and Mn from HMVW.