An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established.The occurrence of various components in copper slag was predicted using sulfur-oxygen potential calcula...An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established.The occurrence of various components in copper slag was predicted using sulfur-oxygen potential calculations and confirmed through high-temperature experiments.The recovery rate of copper can reach 90.13%under the optimal conditions of 1200°C,an iron to silicon mass ratio of 1.0,3 wt.%ferrous sulfide,and a duration of 45 min.Lead(54.07 wt.%)and zinc(17.42 wt.%)are found in the flue dust as lead sulfate,lead sulfide,and zinc oxide,while copper matte contains lead(14.44 wt.%)and zinc sulfide(1.29 wt.%).The remaining lead and zinc are encapsulated as oxides within the fayalite phase.展开更多
在相对真空下以CaSi_(2)为还原剂进行预制球团提镁过程的研究。利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分别对还原渣的形貌、化学成分和物相进行分析。结果表明,小的氩气流量可以极大地提高氧化镁的还原率,在相对真空...在相对真空下以CaSi_(2)为还原剂进行预制球团提镁过程的研究。利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分别对还原渣的形貌、化学成分和物相进行分析。结果表明,小的氩气流量可以极大地提高氧化镁的还原率,在相对真空下以CaSi_(2)为还原剂的预制球团提镁过程可以用F_(1)模型解释,CaSi_(2)还原氧化镁为固液反应,此过程为化学反应控制,温度对还原率影响很大,表观活化能为108.99 k J/mol。还原渣的物相分析表明,渣中的MgO含量对Ca_(2)SiO_(4)的晶型转变有影响。展开更多
To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy ...To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The result shows that the vana-dium slag is composed of major phases of fayalite, titanomagnetite, and spinel. During the high pressure oxidative acid leaching process, the fayalite and spinel phases are gradually decomposed by sulfuric acid, causing the release of vanadium and iron in the solution. Meanwhile, unreacted silicon and titanium are enriched in the leach residues. With the initial concentration of sulfuric acid at 250 g·L^-1, a leaching tem-perature of 140℃, a leaching time of 50 min, a liquid-solid ratio of 10：1 mL·g^-1, and oxygen pressure at 0.2 MPa, the leaching rate of vana-dium reaches 97.69%.展开更多
Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-ca...Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of im- portant parameters such as temperature, amount of CaO added, and CO2 partial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of Na2O to Fe2O3 and of Al2O3 to Fe2O3 from 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% Na2O can potentially be used as a construction material.展开更多
The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. ...The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham's theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10^(-11)n^(3.65)T^(2.08)P_g^(0.18). It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.展开更多
An effective method was reported to prepare low-oxygen Ti powder,which included two experimental steps:the fast conversion of TiO_(2) to TiO_(x<1) powder by self-propagating high-temperature synthesis(SHS)process a...An effective method was reported to prepare low-oxygen Ti powder,which included two experimental steps:the fast conversion of TiO_(2) to TiO_(x<1) powder by self-propagating high-temperature synthesis(SHS)process and the generation of low-oxygen Ti powder by electrodeoxidizing TiO_(x<1) powder at the cathode in molten CaCl_(2).The key intermediate steps were analyzed by XRD,SEM and electrochemical testing techniques.The results demonstrated that TiO_(x<1) powder(TiO_(0.325) and TiO_(0.97))was generated after acid leaching MgO in SHS products with TiO_(2)/Mg molar ratio of 1:2,and the TiO_(x<1) powder with 16.3 wt.%oxygen could be transformed into pure titanium powder with 0.121 wt.%oxygen by electrodeoxidation at a constant potential of−3.3 V for 10 h.The electrodeoxidation of TiO_(x<1) powder in CaCl_(2) molten salt follows the step-by-step deoxidation mode,and the lattice of TiO_(x<1) powder after electrodeoxidation shrinks.展开更多
Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In ...Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.展开更多
α-Ni(OH)2 was synthesized from a NiCl2 solution by electrodeposition method.In order to conduct a systematic study on the effects of experimental parameters,a series of electrolyte initial pH values,current densities...α-Ni(OH)2 was synthesized from a NiCl2 solution by electrodeposition method.In order to conduct a systematic study on the effects of experimental parameters,a series of electrolyte initial pH values,current densities,electrodeposition temperatures,and electrodeposition time were used.Cyclic voltammetry results demonstrated a side reaction of Ni^2++2e→Ni.The X-ray diffraction analysis,Fourier-transform infrared spectrum,and the color of the product showed that pureα-Ni(OH)2 could be obtained in the initial pH value range of 2−5.86,current density range of 10−25 mA/cm^2,electrodeposition temperature range of 25−35℃,and electrodeposition time range of 1.0−3.0 h.When electrodeposition temperature increased to 45℃,a mixture ofα-Ni(OH)2 and metallic Ni was obtained.A current density higher than 30 mA/cm^2 resulted in the sample with features ofβ-Ni(OH)2.A small amount of metallic Ni existed in the as-prepared sample when current density decreased to 5 mA/cm^2.A slight increase of electrolyte pH was observed with increasing initial solution pH and current density.Electrodeposition mass revealed a slight decrease with initial pH decreasing and showed an almost linear increase with current density increasing.The slope of the curve for electrodeposition mass versus electrodeposition time remained stable in the first 2.0 h and then decreased.展开更多
The potential autoclave was used to study the catalytic mechanism of Cu^2+during the oxygen pressure leaching process of artificial sphalerite.By studying the potential change of the system at different temperatures a...The potential autoclave was used to study the catalytic mechanism of Cu^2+during the oxygen pressure leaching process of artificial sphalerite.By studying the potential change of the system at different temperatures and the SEM–EDS difference of the leaching residues,it was found that in the temperature range of 363–423 K,the internal Cu^2+formed a Cu S deposit on the surface of sphalerite,which hindered the leaching reaction,resulting in a zinc leaching rate of only 51.04%.When the temperature exceeds 463 K,the system potential increases steadily.The increase in temperature leads to the dissolution of the CuS,which is beneficial to the circulation catalysis of Cu^2+.At this time,the leaching rate of Zn exceeds 95%.In addition,the leaching kinetics equations at 363–423 and 423–483 K were established.The activation energy of zinc leaching at 363–423 and 423–483 K is 38.66 and 36.25 kJ/mol,respectively,and the leaching process is controlled by surface chemical reactions.展开更多
In order to achieve high-efficiency alkali conversion and impurity removal of high titanium slag under the condition of low alkali concentration,a new way of oxygen-rich alkali conversion in KOH solution was proposed....In order to achieve high-efficiency alkali conversion and impurity removal of high titanium slag under the condition of low alkali concentration,a new way of oxygen-rich alkali conversion in KOH solution was proposed.The conversion law of element occurrence state and the influence of the conversion conditions on the titanium conversion rate and removal rate of silicon and aluminum were studied.The results showed that the KOH solution converted the titanium oxide in high titanium slag into whisker-like potassium titanate.Silicon and aluminum elements were dissolved into the solution.Under the following conditions,KOH concentration of 6 mol/L,conversion temperature of 260℃,initial oxygen partial pressure of 2 MPa,liquid−solid ratio of 35 mL/g,conversion time of 4 h,and high titanium slag particle size of 48−74μm,the conversion rate of titanium was 97.0%,and the removal rates of silicon and aluminum were 90.2%and 76.2%,respectively.Oxygen-rich alkali conversion product was converted to rutile with a TiO_(2) grade of 99.1%by acid hydrolysis conversion.展开更多
To comprehensively utilize the low-iron high-vanadium-titanium magnetite,a new method of vortex smelting reduction of vanadium-titanium magnetite was proposed,and the enrichment and reconstitution regularity of Ti-bea...To comprehensively utilize the low-iron high-vanadium-titanium magnetite,a new method of vortex smelting reduction of vanadium-titanium magnetite was proposed,and the enrichment and reconstitution regularity of Ti-bearing phases in the slag was investigated through X-ray fluorescence spectrometry,X-ray photoelectron spectroscopy,X-ray diffraction analysis,and optical microscopy.The phase diagram revealed that the preferential crystallization of MgTi_(2)O_(5) can be achieved by adjusting the CaO,MgO,and TiO_(2) contents of slag.The predominant Ti-bearing phases in the slag obtained from the reduction process are MgxTi_(3_x)O_(5)(0≤x≤1)and CaTiO_(3).FeTiO_(3) is present at carbon-iron ratio(CR)=1.3,while MgTi_(2)O4 and TiC are formed at CR=1.3.The enrichment of TiO_(2) in the slag increases first and then decreases as the CR increases,and at CR=1.1,the enrichment of TiO_(2) in the slag reaches 51.3 wt.%.Additionally,the concentrations of MgxTi_(3_x)O_(5)(0≤x≤1)and CaTiO_(3) in the slag,along with the grain width of MgxTi_(3_x)O_(5)(0≤x≤1),decrease with the increase in CR.展开更多
In this paper,a new electrolysis device was presented with corundum crucible as an electrolytic cell in place of a graphite crucible,and in the corundum crucible a sleeve with a cathode pellet with a fluted base place...In this paper,a new electrolysis device was presented with corundum crucible as an electrolytic cell in place of a graphite crucible,and in the corundum crucible a sleeve with a cathode pellet with a fluted base placed flat in it was adopted to separate the cathode and anode.The process of electrochemical reduction of solid TiO_(2) to Ti in situ was studied and characterized by the time-current curves and X-ray diffraction(XRD) patterns of the electrochemical reduction products.The influence of CaCl_(2)doping in the cathode and the electrolysis device structures on electrochemical reduction mechanisms and the process strengthening was systematically studied.The results show that the oxygen content in the obtained Ti is reduced to0.51% with a cathode pellet sintering temperature of1000 ℃,sample preparation pressure of 20 MPa and CaCl_(2) doping amount of 30%.Tiny holes are formed in the cathode pellet by CaCl_(2) doping in the electrochemical reduction process,which could increase the contact area between the electrolyte and cathode and improve the electrode reaction efficiency.The new electrolysis device could reduce the carbon content in the molten salt,cathode polarization and the electrode reaction overvoltage,inhibit the chances of secondary reactions,increase the contact area between the produced Ca and cathode and strengthen the thermal reduction of TiO_(2) by Ca.展开更多
A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to cond...A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.展开更多
The kinetics of oxygen pressure acid leaching marmatite with high indium content was studied. The effects of particle size, agitation rate, temperature, HSOconcentration, and oxygen partial pressure on leaching rate o...The kinetics of oxygen pressure acid leaching marmatite with high indium content was studied. The effects of particle size, agitation rate, temperature, HSOconcentration, and oxygen partial pressure on leaching rate of indium were investigated. The results show that when the agitation rate is above 600 r-min, its influence on indium leaching rate is insignificant. It is determined that the leaching rates increase with the increase in sulfuric acid concentration, temperature, partial oxygen pressure, and the decrease in particle size. Moreover, the results demonstrate that the process of indium leaching is controlled by interface chemical reaction, with apparent activation energy of 65.7 k J-mol. The apparent reaction orders of sulfuric acid and oxygen partial pressure are determined to be 0.749 and 1.260, respectively. The leaching reaction process follows shrinking unreacted core model. And finally, the kinetics model equation is established for indium.展开更多
In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO2-C- C12 system show that when C is excess in the solid phas...In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO2-C- C12 system show that when C is excess in the solid phase, titanium tetrachloride and carbon monoxide can exist sta- bly. At high temperature, the reaction with CO as the product is the dominant reaction. The appropriate reaction conditions are as follows： reaction temperature of 950 ℃, reaction time of 40 min, carbon ratio of 30 wt% of rutile, natural rutile particle size of -96 μm, petroleum coke size of -150 μm, and chlorine flow of 0.036 m3.h-1. Under the above conditions, the reaction conversion rate of TiO2 can reach about 95 %. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is generally consistent with the experimental data. For the TiO2-C-C12 system, the reaction rate is dependent on the initial radius of rutile particle, density, and the partial pressures of C12. From 900 to 1,000 ℃, the apparent activation energy is 10.569 kJ.mo1-1, and the mass diffu- sion is found to be the main reaction-controlling step. The expression for the chlorine reaction rate in the C-C12 sys- tem is obtained, and it depends on the degree of reaction, the partial pressure of C12, and the size of rutile particle.展开更多
Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central p...Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist^ersion in the bath.展开更多
Ferrotitanium is used as a deoxidizer and alloying agent during steelmaking process,which has a high demand for sulfur control.Sulfur was introduced from raw materials in the process of producing ferrotitanium by ther...Ferrotitanium is used as a deoxidizer and alloying agent during steelmaking process,which has a high demand for sulfur control.Sulfur was introduced from raw materials in the process of producing ferrotitanium by thermite method,where CaO was used as fluxing agent.At the same time,CaO has a great desulfurization capability.Effects of CaO addition on the distribution of sulfur in high titanium ferroalloy prepared by thermite method were studied in this work.The equilibrium diagram of Ti-AlFe-S system was calculated by FactSage 6.4 software package with FactPS and FTmisc database.The alloy and slag samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),X-ray fluorescence(XRF)and high-frequency infrared ray carbon sulfur analyzer.The result indicates that the sulfur in the alloy firstly exists in the form of liquid FeS,thereafter TiS(s)and eventually Ti2 S(s)during cooling.The sulfur is mainly distributed in the alloy,and only a small amount of sulfur remains in the slag.Moreover,it is noted that the sulfur in the alloy does not distribute homogeneously,and it exists in the form of solid solution phase,(Ti,Al,Fe)S.S content in the slag,the sulfur capacity of the slag and the sulfur distribution ratio(LS)all increase with the increment of CaO addition,while S content in alloys decreases.展开更多
The process of pressure leaching the converter vanadium slag with waste titanium dioxide without roasting was studied. Mineralogy analysis indicates that the con- verter vanadium slag contains mainly three mineral pha...The process of pressure leaching the converter vanadium slag with waste titanium dioxide without roasting was studied. Mineralogy analysis indicates that the con- verter vanadium slag contains mainly three mineral phases： magnetite, titanium magnetite, and silicate phase. Vana- dium is in combination with iron, titanium, manganese, aluminum, and silicon. The impacts of leaching tempera- ture, leaching time, stirring speed, liquid-to-solid ratio, and initial leaching agent concentration were investigated on the waste titanium dioxide leaching process. The results indi- cate that under the optimal conditions, the vanadium and the iron leaching rates are 96.85 % and 93.50 %, respectively, and the content of titanium is 12.6 % in the residue. The main mineral phases for the residues under the optimal operation conditions are quartz, ilmenite, anatase, and sili- cate phase, and the residues can be reused as the extraction of titanium raw materials for titanium dioxide production technology by the sulfate method.展开更多
基金supported by the Fundamental Research Funds for Central Universities,China(No.N2025004)the National Natural Science Foundation of China(Nos.U2102213,U1702253,52204419)+2 种基金Major Science and Technology Project of Liaoning Province,China(No.2021JH1/10400032)Major Science and Technology Project of Guangxi Province,China(No.2021AA12013)Liaoning Natural Science Foundation,China(No.2022-BS-076)。
文摘An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established.The occurrence of various components in copper slag was predicted using sulfur-oxygen potential calculations and confirmed through high-temperature experiments.The recovery rate of copper can reach 90.13%under the optimal conditions of 1200°C,an iron to silicon mass ratio of 1.0,3 wt.%ferrous sulfide,and a duration of 45 min.Lead(54.07 wt.%)and zinc(17.42 wt.%)are found in the flue dust as lead sulfate,lead sulfide,and zinc oxide,while copper matte contains lead(14.44 wt.%)and zinc sulfide(1.29 wt.%).The remaining lead and zinc are encapsulated as oxides within the fayalite phase.
基金supported by the National Key R&D Program of China(No.2021YFE0102200)the Inner Mongolia Natural Science Foundation,China(No.2020MS05063)the Inner Mongolia Science and Technology Plan Project,China(No.2020GG0230)。
基金the financial supports from the Chinese Academy of Sciences,China(No.E055A101)the Science and Technology Project of Shen-Fu Reform and innovation Demonstration Zone,China(No.2021JH15)the National Natural Science Foundation of China(No.U1710257)。
基金supported by the National Natural Science Foundation of China(Nos.U1508217,51504058)the Fundamental Research Funds for the Central Universities of China(No.N162504003)。
文摘在相对真空下以CaSi_(2)为还原剂进行预制球团提镁过程的研究。利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分别对还原渣的形貌、化学成分和物相进行分析。结果表明,小的氩气流量可以极大地提高氧化镁的还原率,在相对真空下以CaSi_(2)为还原剂的预制球团提镁过程可以用F_(1)模型解释,CaSi_(2)还原氧化镁为固液反应,此过程为化学反应控制,温度对还原率影响很大,表观活化能为108.99 k J/mol。还原渣的物相分析表明,渣中的MgO含量对Ca_(2)SiO_(4)的晶型转变有影响。
基金supported by the National High Technology Research and Development Program of China(No.2012AA062303)the National Natural Science Foundation of China(Nos.U1202274,51004033,and 51204040)the Doctoral Fund Project of China(No. 20120042110011)
文摘To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The result shows that the vana-dium slag is composed of major phases of fayalite, titanomagnetite, and spinel. During the high pressure oxidative acid leaching process, the fayalite and spinel phases are gradually decomposed by sulfuric acid, causing the release of vanadium and iron in the solution. Meanwhile, unreacted silicon and titanium are enriched in the leach residues. With the initial concentration of sulfuric acid at 250 g·L^-1, a leaching tem-perature of 140℃, a leaching time of 50 min, a liquid-solid ratio of 10：1 mL·g^-1, and oxygen pressure at 0.2 MPa, the leaching rate of vana-dium reaches 97.69%.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(No.U1202274)the National Natural Science Foundation of China(No.51204040)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China(No.20120042110011)the Fundamental Research Funds for the Central Universities(No.N140204015)
文摘Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of im- portant parameters such as temperature, amount of CaO added, and CO2 partial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of Na2O to Fe2O3 and of Al2O3 to Fe2O3 from 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% Na2O can potentially be used as a construction material.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China (Nos.U1402271, 51504058, and 51504059)
文摘The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham's theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10^(-11)n^(3.65)T^(2.08)P_g^(0.18). It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.
基金supported by the National Natural Science Foundation of China(Nos.52174333,U1908225,1702253)the Fundamental Research Funds for Central Universities,China(Nos.N182515007,N170908001,N2025004).
文摘An effective method was reported to prepare low-oxygen Ti powder,which included two experimental steps:the fast conversion of TiO_(2) to TiO_(x<1) powder by self-propagating high-temperature synthesis(SHS)process and the generation of low-oxygen Ti powder by electrodeoxidizing TiO_(x<1) powder at the cathode in molten CaCl_(2).The key intermediate steps were analyzed by XRD,SEM and electrochemical testing techniques.The results demonstrated that TiO_(x<1) powder(TiO_(0.325) and TiO_(0.97))was generated after acid leaching MgO in SHS products with TiO_(2)/Mg molar ratio of 1:2,and the TiO_(x<1) powder with 16.3 wt.%oxygen could be transformed into pure titanium powder with 0.121 wt.%oxygen by electrodeoxidation at a constant potential of−3.3 V for 10 h.The electrodeoxidation of TiO_(x<1) powder in CaCl_(2) molten salt follows the step-by-step deoxidation mode,and the lattice of TiO_(x<1) powder after electrodeoxidation shrinks.
基金the National Natural Science Foundation of China(Nos.51874078,U1710257,U1202274,and 51764039)the Open Fund of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education)Northeastern University,China(No.NEMM2019004).
文摘Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method,which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method.In this study,the effect of the silica saturation coefficient(x)on the carbonation of hydrogarnet was investigated from the kinetic perspective.The results indicated that the carbonation of hydrogarnets with different x values(x=0.27,0.36,0.70,and 0.73)underwent two stages with significantly different rates,and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3.The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol,respectively.Moreover,the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.
基金Project(U1710257)supported by the National Natural Science Foundation of China。
文摘α-Ni(OH)2 was synthesized from a NiCl2 solution by electrodeposition method.In order to conduct a systematic study on the effects of experimental parameters,a series of electrolyte initial pH values,current densities,electrodeposition temperatures,and electrodeposition time were used.Cyclic voltammetry results demonstrated a side reaction of Ni^2++2e→Ni.The X-ray diffraction analysis,Fourier-transform infrared spectrum,and the color of the product showed that pureα-Ni(OH)2 could be obtained in the initial pH value range of 2−5.86,current density range of 10−25 mA/cm^2,electrodeposition temperature range of 25−35℃,and electrodeposition time range of 1.0−3.0 h.When electrodeposition temperature increased to 45℃,a mixture ofα-Ni(OH)2 and metallic Ni was obtained.A current density higher than 30 mA/cm^2 resulted in the sample with features ofβ-Ni(OH)2.A small amount of metallic Ni existed in the as-prepared sample when current density decreased to 5 mA/cm^2.A slight increase of electrolyte pH was observed with increasing initial solution pH and current density.Electrodeposition mass revealed a slight decrease with initial pH decreasing and showed an almost linear increase with current density increasing.The slope of the curve for electrodeposition mass versus electrodeposition time remained stable in the first 2.0 h and then decreased.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(Nos.51804136,U1402271,51764016)Jiangxi Province Nature Science Foundation,China(No.20181BAB216017)+1 种基金Jiangxi Science and Technology Landing Project,China(No.KJLD13046)Research Fund Program of State Key Laboratory of Rare Metals Separaten and Comprehensive Utilization,Guangzhou,China(No.GK-201803)。
文摘The potential autoclave was used to study the catalytic mechanism of Cu^2+during the oxygen pressure leaching process of artificial sphalerite.By studying the potential change of the system at different temperatures and the SEM–EDS difference of the leaching residues,it was found that in the temperature range of 363–423 K,the internal Cu^2+formed a Cu S deposit on the surface of sphalerite,which hindered the leaching reaction,resulting in a zinc leaching rate of only 51.04%.When the temperature exceeds 463 K,the system potential increases steadily.The increase in temperature leads to the dissolution of the CuS,which is beneficial to the circulation catalysis of Cu^2+.At this time,the leaching rate of Zn exceeds 95%.In addition,the leaching kinetics equations at 363–423 and 423–483 K were established.The activation energy of zinc leaching at 363–423 and 423–483 K is 38.66 and 36.25 kJ/mol,respectively,and the leaching process is controlled by surface chemical reactions.
基金supported by the National Natural Science Foundation of China(Nos.U1908225,U1702253)Fundamental Research Funds for the Central Universities of China(Nos.N182515007,N170908001,N2025004)。
文摘In order to achieve high-efficiency alkali conversion and impurity removal of high titanium slag under the condition of low alkali concentration,a new way of oxygen-rich alkali conversion in KOH solution was proposed.The conversion law of element occurrence state and the influence of the conversion conditions on the titanium conversion rate and removal rate of silicon and aluminum were studied.The results showed that the KOH solution converted the titanium oxide in high titanium slag into whisker-like potassium titanate.Silicon and aluminum elements were dissolved into the solution.Under the following conditions,KOH concentration of 6 mol/L,conversion temperature of 260℃,initial oxygen partial pressure of 2 MPa,liquid−solid ratio of 35 mL/g,conversion time of 4 h,and high titanium slag particle size of 48−74μm,the conversion rate of titanium was 97.0%,and the removal rates of silicon and aluminum were 90.2%and 76.2%,respectively.Oxygen-rich alkali conversion product was converted to rutile with a TiO_(2) grade of 99.1%by acid hydrolysis conversion.
基金financially supported by the National Natural Science Foundation of China (U1908225)the Fundamental Research Funds for Central Universities (N2225012 and N232405-06).
文摘To comprehensively utilize the low-iron high-vanadium-titanium magnetite,a new method of vortex smelting reduction of vanadium-titanium magnetite was proposed,and the enrichment and reconstitution regularity of Ti-bearing phases in the slag was investigated through X-ray fluorescence spectrometry,X-ray photoelectron spectroscopy,X-ray diffraction analysis,and optical microscopy.The phase diagram revealed that the preferential crystallization of MgTi_(2)O_(5) can be achieved by adjusting the CaO,MgO,and TiO_(2) contents of slag.The predominant Ti-bearing phases in the slag obtained from the reduction process are MgxTi_(3_x)O_(5)(0≤x≤1)and CaTiO_(3).FeTiO_(3) is present at carbon-iron ratio(CR)=1.3,while MgTi_(2)O4 and TiC are formed at CR=1.3.The enrichment of TiO_(2) in the slag increases first and then decreases as the CR increases,and at CR=1.1,the enrichment of TiO_(2) in the slag reaches 51.3 wt.%.Additionally,the concentrations of MgxTi_(3_x)O_(5)(0≤x≤1)and CaTiO_(3) in the slag,along with the grain width of MgxTi_(3_x)O_(5)(0≤x≤1),decrease with the increase in CR.
基金financially supported by the National Key Basic Research Program of China (No.2013CB6326062)the Fundamental Research Funds for the Central Universities (Nos.N110202003 and N130102002)the National Natural Science Foundation of China (Nos.51274064 and 51422403)。
文摘In this paper,a new electrolysis device was presented with corundum crucible as an electrolytic cell in place of a graphite crucible,and in the corundum crucible a sleeve with a cathode pellet with a fluted base placed flat in it was adopted to separate the cathode and anode.The process of electrochemical reduction of solid TiO_(2) to Ti in situ was studied and characterized by the time-current curves and X-ray diffraction(XRD) patterns of the electrochemical reduction products.The influence of CaCl_(2)doping in the cathode and the electrolysis device structures on electrochemical reduction mechanisms and the process strengthening was systematically studied.The results show that the oxygen content in the obtained Ti is reduced to0.51% with a cathode pellet sintering temperature of1000 ℃,sample preparation pressure of 20 MPa and CaCl_(2) doping amount of 30%.Tiny holes are formed in the cathode pellet by CaCl_(2) doping in the electrochemical reduction process,which could increase the contact area between the electrolyte and cathode and improve the electrode reaction efficiency.The new electrolysis device could reduce the carbon content in the molten salt,cathode polarization and the electrode reaction overvoltage,inhibit the chances of secondary reactions,increase the contact area between the produced Ca and cathode and strengthen the thermal reduction of TiO_(2) by Ca.
基金the National Natural Science Foundation of China (Nos.52304364,U1710257)the financial support of the National Key Research and Development Program of China (No.2022YFB3504502)。
文摘A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.
基金financially supported by the National High-Tech Research and Development Program of China (No. 2012AA062303)the National Natural Science Foundation of China (Nos. U1402271, 51504059 and 51504058)
文摘The kinetics of oxygen pressure acid leaching marmatite with high indium content was studied. The effects of particle size, agitation rate, temperature, HSOconcentration, and oxygen partial pressure on leaching rate of indium were investigated. The results show that when the agitation rate is above 600 r-min, its influence on indium leaching rate is insignificant. It is determined that the leaching rates increase with the increase in sulfuric acid concentration, temperature, partial oxygen pressure, and the decrease in particle size. Moreover, the results demonstrate that the process of indium leaching is controlled by interface chemical reaction, with apparent activation energy of 65.7 k J-mol. The apparent reaction orders of sulfuric acid and oxygen partial pressure are determined to be 0.749 and 1.260, respectively. The leaching reaction process follows shrinking unreacted core model. And finally, the kinetics model equation is established for indium.
基金financially supported by the National Natural Science Foundation of China(Nos.51374064,51004033,and 51074044)the National High-Tech Research and Development Program of China(No.2012AA062303)+1 种基金the National Key Technology Support Program during the 12th Five-Year Plan Period(No.2012BAE01B02)the Fundamental Research Funds for the Central Universities(Nos.N130402012 and N130702001)
文摘In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO2-C- C12 system show that when C is excess in the solid phase, titanium tetrachloride and carbon monoxide can exist sta- bly. At high temperature, the reaction with CO as the product is the dominant reaction. The appropriate reaction conditions are as follows： reaction temperature of 950 ℃, reaction time of 40 min, carbon ratio of 30 wt% of rutile, natural rutile particle size of -96 μm, petroleum coke size of -150 μm, and chlorine flow of 0.036 m3.h-1. Under the above conditions, the reaction conversion rate of TiO2 can reach about 95 %. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is generally consistent with the experimental data. For the TiO2-C-C12 system, the reaction rate is dependent on the initial radius of rutile particle, density, and the partial pressures of C12. From 900 to 1,000 ℃, the apparent activation energy is 10.569 kJ.mo1-1, and the mass diffu- sion is found to be the main reaction-controlling step. The expression for the chlorine reaction rate in the C-C12 sys- tem is obtained, and it depends on the degree of reaction, the partial pressure of C12, and the size of rutile particle.
基金Item Sponsored by National Natural Science Foundation of China(50974035,51074047)National High Technology Research and Development Program(863 Program)of China(2010AA03A405,2012AA062303)Innovation Team Project of Provincial Science and Technology of Liaoning Province of China(LT2010034)
文摘Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist^ersion in the bath.
基金financially supported by the National Natural Science Foundation of China(Nos.51422403 and51504064)the Fundamental Research Funds for the Central Universities(No.N162505002)the National Basic Research Program of China(No.2013CB632606)
文摘Ferrotitanium is used as a deoxidizer and alloying agent during steelmaking process,which has a high demand for sulfur control.Sulfur was introduced from raw materials in the process of producing ferrotitanium by thermite method,where CaO was used as fluxing agent.At the same time,CaO has a great desulfurization capability.Effects of CaO addition on the distribution of sulfur in high titanium ferroalloy prepared by thermite method were studied in this work.The equilibrium diagram of Ti-AlFe-S system was calculated by FactSage 6.4 software package with FactPS and FTmisc database.The alloy and slag samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),X-ray fluorescence(XRF)and high-frequency infrared ray carbon sulfur analyzer.The result indicates that the sulfur in the alloy firstly exists in the form of liquid FeS,thereafter TiS(s)and eventually Ti2 S(s)during cooling.The sulfur is mainly distributed in the alloy,and only a small amount of sulfur remains in the slag.Moreover,it is noted that the sulfur in the alloy does not distribute homogeneously,and it exists in the form of solid solution phase,(Ti,Al,Fe)S.S content in the slag,the sulfur capacity of the slag and the sulfur distribution ratio(LS)all increase with the increment of CaO addition,while S content in alloys decreases.
基金financially supported by the Chinese National Programs for High Technology Research and Development(Nos.2010AA03A405 and 2012AA062303)the National Natural Science Foundation of China(Nos.U1202274,51004033,51204040,and 50974035)+2 种基金the National Science and Technology Support Program(No.2012BAE01B02)the Fundamental Research Funds for the Central Universities(No.N100302005)the Doctoral Fund Project(No.20120042110011)
文摘The process of pressure leaching the converter vanadium slag with waste titanium dioxide without roasting was studied. Mineralogy analysis indicates that the con- verter vanadium slag contains mainly three mineral phases： magnetite, titanium magnetite, and silicate phase. Vana- dium is in combination with iron, titanium, manganese, aluminum, and silicon. The impacts of leaching tempera- ture, leaching time, stirring speed, liquid-to-solid ratio, and initial leaching agent concentration were investigated on the waste titanium dioxide leaching process. The results indi- cate that under the optimal conditions, the vanadium and the iron leaching rates are 96.85 % and 93.50 %, respectively, and the content of titanium is 12.6 % in the residue. The main mineral phases for the residues under the optimal operation conditions are quartz, ilmenite, anatase, and sili- cate phase, and the residues can be reused as the extraction of titanium raw materials for titanium dioxide production technology by the sulfate method.
