It is difficult to recover chrysocolla from sulfidation flotation which is closely related to the mineral surface composition.In this study,the effects of fluoride roasting on the surface composition of chrysocolla we...It is difficult to recover chrysocolla from sulfidation flotation which is closely related to the mineral surface composition.In this study,the effects of fluoride roasting on the surface composition of chrysocolla were investigated,its impact on sulfidation flotation was explored,and the mechanisms involved in both fluoride roasting and sulfidation flotation were discussed.With CaF_(2)as the roasting reagent,Na_(2)S·9H_(2)O as the sulfidation reagent,and sodium butyl xanthate(NaBX)as the collector,the results of the flotation experiments showed that fluoride roasting improved the floatability of chrysocolla,and the recovery rate increased from 16.87%to 82.74%.X-ray diffraction analysis revealed that after fluoride roasting,approximately all the Cu on the chrysocolla surface was exposed in the form of CuO,which could provide a basis for subsequent sulfidation flotation.The microscopy and elemental analyses revealed that large quantities of"pagoda-like"grains were observed on the sulfidation surface of the fluoride-roasted chrysocolla,indicating high crystallinity particles of copper sulfide.This suggests that the effect of sulfide formation on the chrysocolla surface was more pronounced.X-ray photoelectron spectroscopy revealed that fluoride roasting increased the relative contents of sulfur and copper on the surface and that both the Cu~+and polysulfide fractions on the surface of the minerals increased.This enhances the effect of sulfidation,which is conducive to flotation recovery.Therefore,fluoride roasting improved the effect of copper species transformation and sulfidation on the surface of chysocolla,promoted the adsorption of collectors,and improved the recovery of chrysocolla from sulfidation flotation.展开更多
To explore the spontaneous magnetization of iron-bearing rare earth ores during suspension roasting,binary minerals containing hematite and bastnaesite were used to investigate the effects of the roasting temperature,...To explore the spontaneous magnetization of iron-bearing rare earth ores during suspension roasting,binary minerals containing hematite and bastnaesite were used to investigate the effects of the roasting temperature,roasting time,and bastnaesite-to-hematite mass ratio on in-situ reduction of hematite in a N_(2)atmosphere.Relevant analytical tests were used to explore the mineral phase evolution during roasting,the magnetism and microstructure of the roasted products,the phase composition,and the surface element valence of concentrate.It was found that magnetic separation of the iron concentrate afforded an iron grade of 68.87%and a recovery of 93.18%under the optimum roasting conditions.During roasting,bastnaesite decomposed to generate CO_(2)and CO,and the compact structure of hematite was gradually destroyed,resulting in microcracks.Subsequently,the CO entered the surface of the hematite through the microcracks and reacted to form a magnetite shell,and the magnetite-encapsulated hematite particles were recovered via low-intensity magnetic separation.展开更多
A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vana...A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.展开更多
With the continuous increase in the disposal volume of spent lithium-ion batteries(LIBs),properly recycling spent LIBs has become essential for the advancement of the circular economy.This study presents a systematic ...With the continuous increase in the disposal volume of spent lithium-ion batteries(LIBs),properly recycling spent LIBs has become essential for the advancement of the circular economy.This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials.The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free,model-fitting,and Z(α)function(αis conversion rate).Results indicated that the reaction was dominated by the first-order(F1)model when the conversion rate was less than or equal to 0.5 and shifted to the second-order(F2)model when the conversion rate exceeded 0.5.Optimal conditions were determined by thoroughly investigating the effects of roasting temperature,roasting time,and the mass ratio of NH_(4)Cl to LiCoO_(2).Under the optimal conditions,namely 400℃,20 min,and NH_(4)Cl/LiCoO_(2)mass ratio of 3:1,the leaching efficiency of Li and Co reached 99.43% and 99.05%,respectively.Analysis of the roasted products revealed that valuable metals in LiCoO_(2)transformed into CoCl_(2) and LiCl.Furthermore,the reaction mechanism was elucidated,providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective.This technology can guide the development of LIB recycling processes with low energy consumption,low secondary pollution,high recovery efficiency,and high added value.展开更多
Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction ac...Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction activity of Ti-BFS.A comprehensive utilization route of Ti,Mg and Al from Ti-BFS was proposed.Ti-BFS was firstly roasted with H_(2)SO_(4)to realizes the conversion of Ti,Mg and Al to their corresponding sulphates.The sulphates were leached by dilute H_(2)SO_(4)solution to extraction Ti,Mg and Al from roasted Ti-BFS.The roasting conditions were optimized as follows,sulfuric acid concentration of 85%(mass),temperature of 200℃,acid-slag ratio of 5.5,particle size of Ti-BFS<75μm,and reaction time of 1 h.The extraction rates of titanium,aluminum,and magnesium reached 82.42%,88.78%and 90.53%,respectively.The leachate was hydrolyzed at 102℃for 5 h with a titanium hydrolysis ratio of 96%.After filtration and calcination,TiO_(2)with a purity of 97%(mass)was obtained.Al in the leachate was converted to NH_(4)Al(SO_(4))_(2)·12H_(2)O by the neutralization of ammonia water at pH=4.5.Al_(2)O_(3) was obtained by the calcination of NH_(4)Al(SO_(4))_(2)·12H_(2)O.The residual solution can be used to prepare products of magnesium sulfate.In the proposed process,Ti,Mg and Al were extracted from Ti-BFS and utilized comprehensively to prepare valuable products.The leaching behavior of roasted Ti-BFS with water was also studied.It followed the unreacted shrinking core model.The apparent activation energy was 26.07 kJ·mol^(-1).This research not only provides a viable method for recovering valuable metals in Ti-BFS,but also provides a strategy to comprehensive utilize the valuable elements in Ti-BFS.展开更多
Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a c...Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.展开更多
Addressing the environmental issues of traditional vanadium extraction methods from vanadium-bearing shale,a highly efficient and clean suspension oxidation roasting-curing-leaching process was proposed and semi-indus...Addressing the environmental issues of traditional vanadium extraction methods from vanadium-bearing shale,a highly efficient and clean suspension oxidation roasting-curing-leaching process was proposed and semi-industrial trials were conducted.Vanadium in raw ore mainly exists in sericite,roscoelite,and limonite,predominantly in the forms of V(Ⅲ)and V(Ⅳ).Under the conditions of a feed rate of 30 kg/h,an air flow rate of 28.0 m^(3)/h,an O_(2) flow rate of 4.0 m^(3)/h,and a temperature of 900℃ in both the suspension furnace and fluidized reactor,the vanadium-bearing mica underwent dehydroxylation and transformed into illite-montmorillonite.These changes disrupted the crystal structure of mica,facilitating vanadium extraction.Compared to direct acid leaching,curing-leaching demonstrates better performance in vanadium extraction.Under the conditions of curing temperature of 130℃,acid dosage of 40 wt.%,curing time of 6 h,and leaching time of 3 h,a V_(2)O_(5) leaching efficiency of 83.92% was achieved.展开更多
As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limoni...As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limonite was explored.The micromorphology,microstructure,and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope,an automatic surface area and porosity analyzer,an X-ray diffractometer,and a vibrating sample magnetometer.Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate.Microwave fluidization roasting significantly increased the specific surface area of limonite,increased the opportunity of contact between CO and limonite,and accelerated the transformation from FeO(OH)toα-Fe_(2)O_(3)and then to Fe_(3)O_(4).In addition,the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity,which has a certain activation effect on the reduction roasting of limonite.The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m^(2)·kg^(-1)and 2.50×10^(-4)m^(3)·kg^(-1),respectively.The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt%and a recovery of 90.07wt%.Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model(G(α)=α^(2)),with the mechanism function described as k=0.08208exp[-20.3441/(R_(g)T)].Therefore,microwave fluidization roasting shows significant potential in the beneficiation of limonite,offering a promising approach for the exploitation of refractory iron ores.展开更多
As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-s...As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.展开更多
The growing demand for Ni and Co in the new energy sector necessitates efficient extraction methods for limonitic laterite ores.This study demonstrated the effectiveness of sodium sulfate(Na_(2)SO_(4))as an additive f...The growing demand for Ni and Co in the new energy sector necessitates efficient extraction methods for limonitic laterite ores.This study demonstrated the effectiveness of sodium sulfate(Na_(2)SO_(4))as an additive for enhancing the co-enrichment of Ni and Co during solid-state reduction.Na_(2)SO_(4)promoted the formation of two distinct liquid phases,low-melting-point FeS-FeO-Fe and NaAlSiO_(4)-NaFeSiO_(4),facilitating the migration and aggregation of Ni-Co-Fe alloy particles,leading to a high-grade alloy powder with 11.98wt%Ni and 0.88wt%Co and recoveries of 94.03%and 80.16%,respectively.Ni-Co-Fe particle growth was mainly driven by the FeS-FeO-Fe eutectic melt,aligned with a liquid-phase sintering mechanism.Pilot-scale rotary kiln experiments validated the industrial feasibility of this approach,which offers a promising solution for the sustainable extraction of these critical metals.展开更多
Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relev...Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relevant analytical tests were applied to evaluate the phase and surface property variations of bastnaesite,and isothermal kinetic analysis of bastnaesite pyrolysis and Ce oxidation was performed.The results revealed that bastnaesite decomposed rapidly and accompanied by Ce oxidation,and the gas-solid products were identified as CO_(2),Ce_(7)O_(12),La_(2)O_(3),CeF_(3) and LaF_(3),with Ce oxidation restricted by bastnaesite pyrolysis.As roasting time prolonged,cracks and pores appeared on bastnaesite surface;the BET specific surface and pore diameter increased.In later roasting period,the pore diameter continued to increase but the specific surface decreased,assigned to particle fusion agglomeration and pore consolidation.Additionally,the surface C content reduced and Ce(Ⅳ)content increased gradually as roasting progressed.The reaction kinetics all followed Avrami-Erofeev equations,the reaction orders of bastnaesite pyrolysis and Ce oxidation decreased with decreasing reaction temperature.The calculated activation energies at lower temperatures were higher than those calculated at higher temperatures.This study analyzed the bastnaesite reaction mechanism to supply a reference for the application of suspension roasting technology in bastnaesite smelting.展开更多
Rare earth elements were extracted using a sulfuric acid roasting-water leaching process.The effect of acid roasting on a new type of low-grade sedimentary rare earth ore found in Guizhou Province,China was analyzed u...Rare earth elements were extracted using a sulfuric acid roasting-water leaching process.The effect of acid roasting on a new type of low-grade sedimentary rare earth ore found in Guizhou Province,China was analyzed using X-ray diffraction and scanning electron microscopy.A systematic study was conducted on process parameters such as amount of acid,roasting temperature,roasting time,water leaching temperature,and leaching time.The results reveal that the total recove ry of rare earth elements reaches 81.37%,which is 3.1 times higher than that achieved through direct acid leaching,under the optimal conditions.In addition,the leaching rate of heavy rare earth elements reaches 72.53%.Rare earth elements and some other valuable metals are transformed into soluble sulfate through the local decomposition of clay minerals under the action of the sulfuric acid attack.The dissolution rates of aluminum,iron,and titanium ions are 34.94%,17.05%,and 62.77%,respectively.The precipitation rate of Ti reaches 99%,and the loss of rare earth ions in the solution is less than 1%.Meanwhile,the results of a leaching kinetics analysis indicate that the leaching process of rare ions is controlled by diffusion.Precious metal ions such as iron and aluminum in the leaching solution can reduce the adsorption of rare earth ions by kaolinite.This study efficiently recovered rare earth ions under conditions of low calcination te mperature and direct water leaching,resulting in reduced energy consumption of the extraction process and acidity of the leaching solution.These findings provide a solid foundation for the further separation and extraction of rare earth ions.展开更多
Iron tailings are a common solid waste resource,posing serious environmental and spatial challenges.This study proposed a novel hydrogen-based reduction roasting(HRR)technology for the processing of iron tailings usin...Iron tailings are a common solid waste resource,posing serious environmental and spatial challenges.This study proposed a novel hydrogen-based reduction roasting(HRR)technology for the processing of iron tailings using a combined beneficiation and metallurgy approach.Pilot-cale experiment results indicated that under the gas composition of CO:H_(2)=1:3,and optimal roasting conditions at a reduction temperature of 520℃,the majority of weakly magnetic hematite transforms into strongly magnetic magnetite during the reduction process.Combining roasting products with a magnetic separation-grinding-magnetic selection process yields a final iron concentrate with a grade of 56.68%iron and a recovery rate of 86.54%.Theoretical calculations suggested the annual production value can reach 29.7 million USD and a reduction of 20.79 tons of CO_(2) emissions per year.This highlights that the use of HRR in conjunction with traditional beneficiation processes can effectively achieve comprehensive utilization of iron tailings,thereby reducing environmental impact.展开更多
The ammonium salt precipitation method is frequently utilized for extracting vanadium from the leaching solution obtained through sodium roasting of vanadium slag.However,Na^(+)and NH_(4)^(+)ions in the vanadium preci...The ammonium salt precipitation method is frequently utilized for extracting vanadium from the leaching solution obtained through sodium roasting of vanadium slag.However,Na^(+)and NH_(4)^(+)ions in the vanadium precipitation solution can not be effectively separated,leading to a large amount of ammonia-nitrogen wastewater which is difficult to treat.In this study,the manganese salt pretreatment process is used to extract vanadium from a sodium roasting leaching solution,enabling the separation of vanadium and sodium.The vanadium extraction product of manganese salt is dissolved in acid to obtain vanadium-containing leaching solution,then vanadium is extracted by hydrolysis and vanadium precipitation,and V_(2)O_(5)is obtained after impurity removal and calcination.The results show that the rate of vanadium extraction by manganese salt is 98.23%.The vanadium extraction product by manganese salt is Mn_(2)V_(2)O_(7),and its sodium content is only 0.167%.Additionally,the acid solubility of vanadium extraction products by manganese salt is 99.52%,and the vanadium precipitation rate of manganese vanadate solution is 92.34%.After the removal of manganese and calcination process,the purity of V_(2)O_(5)product reached 97.73%,with a mere 0.64%loss of vanadium.The Mn_(2)^(+)and NH_(4)^(+)ions in the solution after vanadium precipitation are separated by precipitation method,which reduces the generation of ammonia-nitrogen wastewater.This is conducive to the green and sustainable development of the vanadium industry.展开更多
The recovery of lithium from spent lithium-ion batteries(LIBs)is of great importance in addressing lithium shortages and environmental issues.In this study,a novel and clean process for selective separation of lithium...The recovery of lithium from spent lithium-ion batteries(LIBs)is of great importance in addressing lithium shortages and environmental issues.In this study,a novel and clean process for selective separation of lithium from spent LiFePO_(4)cathode material by low temperature oxidative roasting and water leaching was proposed.The effect of several important factors,such as roasting temperature,roasting time,and molar ratio of ferric chloride(FeCl_(3)·6H_(2)O)to lithium iron phosphate(LFP),on the leaching efficiency of lithium and iron was systematically investigated by using single factor experimental method.The results show that approximately 97.1%lithium element was recovered by being converted to water-soluble LiCl at a roasting temperature 350℃,a roasting time 120 min and a FeCl_(3)·6H_(2)O/LFP molar ratio of 1:1,and iron element was enriched in the leaching residue in the form of insoluble FePO_(4).High-purity lithium carbonate products could be prepared from the leching solution by adding Na_(2)CO_(3) after removing iron.The establishment of new cleaning process can provide a scalable,environmentally friendly and simple way to recover valuable metals from spent LFP batteries.展开更多
Chlorination roasting followed by water leaching process was used to extract lithium from lepidolite.The microstructure of the lepidolite and roasted materials were characterized by X-ray diffraction（XRD）.Various pa...Chlorination roasting followed by water leaching process was used to extract lithium from lepidolite.The microstructure of the lepidolite and roasted materials were characterized by X-ray diffraction（XRD）.Various parameters including chlorination roasting temperature,time,type and amount of chlorinating agents were optimized.The conditional experiments indicate that the best mass ratio of lepidolite to NaCl to CaCl2 is 1：0.6：0.4 during the roasting process.The extraction of lithium reaches peak value of 92.86% at 880 °C,potassium,rubidium,and cesium 88.49%,93.60% and 93.01%,respectively.The XRD result indicates that the major phases of the product after roasting lepidolite with mixture of chlorinating agents（CaCl2 and NaCl） are SiO2,CaF2,KCl,CaSiO3,CaAl2Si2O8,NaCl and NaAlSi3O8.展开更多
High phosphorous oolitic hematite ore is one of typical intractable iron ores in China, and the conventional beneficiation methods are found to be impracticable to , remove phosphorus from the ore effectively. Better ...High phosphorous oolitic hematite ore is one of typical intractable iron ores in China, and the conventional beneficiation methods are found to be impracticable to , remove phosphorus from the ore effectively. Better beneficiation index were gotten by direct reduction roasting with dephosphorization agent followed by two stages of grinding and magnetic separation. P content decreases from 0.82% in the raw ore to 0.06% in the magnetic concentrate, and the total iron grade increases from 43.65% to 90.23%, the recovery of iron can reach 87%. Mechanisms of phosphorus removal in the beneficiation of high phosphorous oolitic hematite ore by direct reduction roasting with dephosphorization agent were studied using XRD, SEM and EPMA. The results showed that about 20% of the apatite in the raw ore transferred into phosphorus and volatilized with the gas in the process of reduction roasting, while the rest 80% apatite was not involved in the reaction of generation of phosphorus, and remained as apatite in the roasted products, which was removed to tailings by grinding and magnetic separation. A small amount of phosphorus existed in the magnetic concentrate as apatite. The oolitic texture of raw ore was partly changed during roasting, resulting in the formation of nepheline in the reaction between the dephosphorization agent, SiO2 and Al2O3 in the raw ore, which greatly improved the liberation degree of minerals in the roasted products, and it was beneficial to the subsequent grinding and magnetic separation.展开更多
A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of HaPO4 dosage, roasting temperature, and roasting time on TiO2 grade were investi...A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of HaPO4 dosage, roasting temperature, and roasting time on TiO2 grade were investigated. A Ti-rich material containing 88.54% TiO2, 0.42% （CaO＋MgO） was obtained when finely ground titanium slag was roasted with 7.5% H3PO4 at 1000 ℃ for 2 h, followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h. The XRD patterns show that the product is titanium dioxide with a rutile structure. Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process. As a result, titanium components in titanium slag are transformed into TiO2 （futile） while impurities are transformed into acid-soluble phosphate and quartz.展开更多
In order to investigate the oxidation roasting of molybdenite concentrate in pure oxygen atmosphere, experiments at 673, 723, 773, 873 and 973 K were carried out. The phase transitions and morphology evolutions of the...In order to investigate the oxidation roasting of molybdenite concentrate in pure oxygen atmosphere, experiments at 673, 723, 773, 873 and 973 K were carried out. The phase transitions and morphology evolutions of the samples obtained at different temperatures after reacting for different time were analyzed by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results showed that molybdenite concentrate was oxidized directly to Mo O3 in pure oxygen atmosphere. There were remarkable changes of the morphologies of products with the increase of the roasting temperature. It was also found that sintering phenomenon occurred during the roasting process in pure oxygen when the temperature was above 873 K. The composition of sintered sample was mainly comprised of Mo O3 and some unreacted Mo S2.展开更多
H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to char...H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52374259)the Open Fund of the State Key Laboratory of Mineral Processing Science and Technology,China(No.BGRIMM-KJSKL-2023-11)the Major Science and Technology Projects in Yunnan Province,China(No.202302 AF080004)。
文摘It is difficult to recover chrysocolla from sulfidation flotation which is closely related to the mineral surface composition.In this study,the effects of fluoride roasting on the surface composition of chrysocolla were investigated,its impact on sulfidation flotation was explored,and the mechanisms involved in both fluoride roasting and sulfidation flotation were discussed.With CaF_(2)as the roasting reagent,Na_(2)S·9H_(2)O as the sulfidation reagent,and sodium butyl xanthate(NaBX)as the collector,the results of the flotation experiments showed that fluoride roasting improved the floatability of chrysocolla,and the recovery rate increased from 16.87%to 82.74%.X-ray diffraction analysis revealed that after fluoride roasting,approximately all the Cu on the chrysocolla surface was exposed in the form of CuO,which could provide a basis for subsequent sulfidation flotation.The microscopy and elemental analyses revealed that large quantities of"pagoda-like"grains were observed on the sulfidation surface of the fluoride-roasted chrysocolla,indicating high crystallinity particles of copper sulfide.This suggests that the effect of sulfide formation on the chrysocolla surface was more pronounced.X-ray photoelectron spectroscopy revealed that fluoride roasting increased the relative contents of sulfur and copper on the surface and that both the Cu~+and polysulfide fractions on the surface of the minerals increased.This enhances the effect of sulfidation,which is conducive to flotation recovery.Therefore,fluoride roasting improved the effect of copper species transformation and sulfidation on the surface of chysocolla,promoted the adsorption of collectors,and improved the recovery of chrysocolla from sulfidation flotation.
基金the financial support from the National Key R&D Program of China(No.2022YFC2905800)the National Natural Science Foundation of China(Nos.52174242,52130406)。
文摘To explore the spontaneous magnetization of iron-bearing rare earth ores during suspension roasting,binary minerals containing hematite and bastnaesite were used to investigate the effects of the roasting temperature,roasting time,and bastnaesite-to-hematite mass ratio on in-situ reduction of hematite in a N_(2)atmosphere.Relevant analytical tests were used to explore the mineral phase evolution during roasting,the magnetism and microstructure of the roasted products,the phase composition,and the surface element valence of concentrate.It was found that magnetic separation of the iron concentrate afforded an iron grade of 68.87%and a recovery of 93.18%under the optimum roasting conditions.During roasting,bastnaesite decomposed to generate CO_(2)and CO,and the compact structure of hematite was gradually destroyed,resulting in microcracks.Subsequently,the CO entered the surface of the hematite through the microcracks and reacted to form a magnetite shell,and the magnetite-encapsulated hematite particles were recovered via low-intensity magnetic separation.
基金finally supported by the National Natural Science Foundation of China (Nos.52204309,52174277,52374300)。
文摘A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.
基金financially supported by the National Natural Science Foundation of China(No.52204310)the Guizhou Provincial Key Laboratory of Coal Clean Utilization(No.[2020]2001)+5 种基金the China Postdoctoral Science Foundation(Nos.2020TQ0059 and 2020M570967)the Natural Science Foundation of Liaoning Province(No.2021–MS–083)the Fundamental Research Funds for the Central Universities,China(No.N2125010)the Open Project Program of Key Laboratory of Metallurgical Emission Reduction&Resources Recycling(Anhui University of Technology),Ministry of Education(No.JKF22–02)the Foundation of Liupanshui Normal University(No.LPSSYZDZK202205)the Key Laboratory for Anisotropy and Texture of Materials,Ministry of Education,China。
文摘With the continuous increase in the disposal volume of spent lithium-ion batteries(LIBs),properly recycling spent LIBs has become essential for the advancement of the circular economy.This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials.The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free,model-fitting,and Z(α)function(αis conversion rate).Results indicated that the reaction was dominated by the first-order(F1)model when the conversion rate was less than or equal to 0.5 and shifted to the second-order(F2)model when the conversion rate exceeded 0.5.Optimal conditions were determined by thoroughly investigating the effects of roasting temperature,roasting time,and the mass ratio of NH_(4)Cl to LiCoO_(2).Under the optimal conditions,namely 400℃,20 min,and NH_(4)Cl/LiCoO_(2)mass ratio of 3:1,the leaching efficiency of Li and Co reached 99.43% and 99.05%,respectively.Analysis of the roasted products revealed that valuable metals in LiCoO_(2)transformed into CoCl_(2) and LiCl.Furthermore,the reaction mechanism was elucidated,providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective.This technology can guide the development of LIB recycling processes with low energy consumption,low secondary pollution,high recovery efficiency,and high added value.
基金the Pangang Group Company Limited for its financial supportthe support from the Fundamental Research Funds for the Central Universities(SCU2024D009)。
文摘Titanium-bearing blast furnace slag(Ti-BFS)is an industrial solid waste rich in titanium,magnesium and aluminum.However,it is difficult to utilize Ti,Mg and Al from Ti-BFS for the strong stability and poor reaction activity of Ti-BFS.A comprehensive utilization route of Ti,Mg and Al from Ti-BFS was proposed.Ti-BFS was firstly roasted with H_(2)SO_(4)to realizes the conversion of Ti,Mg and Al to their corresponding sulphates.The sulphates were leached by dilute H_(2)SO_(4)solution to extraction Ti,Mg and Al from roasted Ti-BFS.The roasting conditions were optimized as follows,sulfuric acid concentration of 85%(mass),temperature of 200℃,acid-slag ratio of 5.5,particle size of Ti-BFS<75μm,and reaction time of 1 h.The extraction rates of titanium,aluminum,and magnesium reached 82.42%,88.78%and 90.53%,respectively.The leachate was hydrolyzed at 102℃for 5 h with a titanium hydrolysis ratio of 96%.After filtration and calcination,TiO_(2)with a purity of 97%(mass)was obtained.Al in the leachate was converted to NH_(4)Al(SO_(4))_(2)·12H_(2)O by the neutralization of ammonia water at pH=4.5.Al_(2)O_(3) was obtained by the calcination of NH_(4)Al(SO_(4))_(2)·12H_(2)O.The residual solution can be used to prepare products of magnesium sulfate.In the proposed process,Ti,Mg and Al were extracted from Ti-BFS and utilized comprehensively to prepare valuable products.The leaching behavior of roasted Ti-BFS with water was also studied.It followed the unreacted shrinking core model.The apparent activation energy was 26.07 kJ·mol^(-1).This research not only provides a viable method for recovering valuable metals in Ti-BFS,but also provides a strategy to comprehensive utilize the valuable elements in Ti-BFS.
基金Project supported by the National Natural Science Foundation of China(51964009)。
文摘Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.
基金funded by the National Key Research and Development Program of China(No.2020YFC1909704)the Fundamental Research Funds for the Central Universities,China(Nos.N2301026,N2301017).
文摘Addressing the environmental issues of traditional vanadium extraction methods from vanadium-bearing shale,a highly efficient and clean suspension oxidation roasting-curing-leaching process was proposed and semi-industrial trials were conducted.Vanadium in raw ore mainly exists in sericite,roscoelite,and limonite,predominantly in the forms of V(Ⅲ)and V(Ⅳ).Under the conditions of a feed rate of 30 kg/h,an air flow rate of 28.0 m^(3)/h,an O_(2) flow rate of 4.0 m^(3)/h,and a temperature of 900℃ in both the suspension furnace and fluidized reactor,the vanadium-bearing mica underwent dehydroxylation and transformed into illite-montmorillonite.These changes disrupted the crystal structure of mica,facilitating vanadium extraction.Compared to direct acid leaching,curing-leaching demonstrates better performance in vanadium extraction.Under the conditions of curing temperature of 130℃,acid dosage of 40 wt.%,curing time of 6 h,and leaching time of 3 h,a V_(2)O_(5) leaching efficiency of 83.92% was achieved.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2901000)the National Natural Science Foundation of China(No.52104249)+1 种基金the Liaoning Joint Fund General Support Program Project(No.2023-MSBA-126)the Fundamental Research Funds for the Central Universities(No.N2401019)。
文摘As a refractory iron ore,the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal.In this study,the microwave fluidization magnetization roasting of limonite was explored.The micromorphology,microstructure,and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope,an automatic surface area and porosity analyzer,an X-ray diffractometer,and a vibrating sample magnetometer.Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate.Microwave fluidization roasting significantly increased the specific surface area of limonite,increased the opportunity of contact between CO and limonite,and accelerated the transformation from FeO(OH)toα-Fe_(2)O_(3)and then to Fe_(3)O_(4).In addition,the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity,which has a certain activation effect on the reduction roasting of limonite.The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m^(2)·kg^(-1)and 2.50×10^(-4)m^(3)·kg^(-1),respectively.The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt%and a recovery of 90.07wt%.Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model(G(α)=α^(2)),with the mechanism function described as k=0.08208exp[-20.3441/(R_(g)T)].Therefore,microwave fluidization roasting shows significant potential in the beneficiation of limonite,offering a promising approach for the exploitation of refractory iron ores.
基金supported by the National Key Research and Development Program of China(2022YFC2904400)Guangxi Science and Technology Major Project(Gui Ke AA23023033)。
文摘As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.
基金financially supported by the National Natural Science Foundation of China(Nos.52174288 and 51804346)the Fundamental Research Funds for the Central Universities of Central South University,China(No.1053320231449).
文摘The growing demand for Ni and Co in the new energy sector necessitates efficient extraction methods for limonitic laterite ores.This study demonstrated the effectiveness of sodium sulfate(Na_(2)SO_(4))as an additive for enhancing the co-enrichment of Ni and Co during solid-state reduction.Na_(2)SO_(4)promoted the formation of two distinct liquid phases,low-melting-point FeS-FeO-Fe and NaAlSiO_(4)-NaFeSiO_(4),facilitating the migration and aggregation of Ni-Co-Fe alloy particles,leading to a high-grade alloy powder with 11.98wt%Ni and 0.88wt%Co and recoveries of 94.03%and 80.16%,respectively.Ni-Co-Fe particle growth was mainly driven by the FeS-FeO-Fe eutectic melt,aligned with a liquid-phase sintering mechanism.Pilot-scale rotary kiln experiments validated the industrial feasibility of this approach,which offers a promising solution for the sustainable extraction of these critical metals.
基金Projects(2022YFC2905800,2021YFC2901000)supported by the National Key R&D Program of ChinaProject(52174242)supported by the National Science and Technology of ChinaProject(52130406)supported by the National Science and Technology Major Project of China。
文摘Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relevant analytical tests were applied to evaluate the phase and surface property variations of bastnaesite,and isothermal kinetic analysis of bastnaesite pyrolysis and Ce oxidation was performed.The results revealed that bastnaesite decomposed rapidly and accompanied by Ce oxidation,and the gas-solid products were identified as CO_(2),Ce_(7)O_(12),La_(2)O_(3),CeF_(3) and LaF_(3),with Ce oxidation restricted by bastnaesite pyrolysis.As roasting time prolonged,cracks and pores appeared on bastnaesite surface;the BET specific surface and pore diameter increased.In later roasting period,the pore diameter continued to increase but the specific surface decreased,assigned to particle fusion agglomeration and pore consolidation.Additionally,the surface C content reduced and Ce(Ⅳ)content increased gradually as roasting progressed.The reaction kinetics all followed Avrami-Erofeev equations,the reaction orders of bastnaesite pyrolysis and Ce oxidation decreased with decreasing reaction temperature.The calculated activation energies at lower temperatures were higher than those calculated at higher temperatures.This study analyzed the bastnaesite reaction mechanism to supply a reference for the application of suspension roasting technology in bastnaesite smelting.
基金supported by the Guizhou Provincial Science and Technology Program ([2022]ZD006)。
文摘Rare earth elements were extracted using a sulfuric acid roasting-water leaching process.The effect of acid roasting on a new type of low-grade sedimentary rare earth ore found in Guizhou Province,China was analyzed using X-ray diffraction and scanning electron microscopy.A systematic study was conducted on process parameters such as amount of acid,roasting temperature,roasting time,water leaching temperature,and leaching time.The results reveal that the total recove ry of rare earth elements reaches 81.37%,which is 3.1 times higher than that achieved through direct acid leaching,under the optimal conditions.In addition,the leaching rate of heavy rare earth elements reaches 72.53%.Rare earth elements and some other valuable metals are transformed into soluble sulfate through the local decomposition of clay minerals under the action of the sulfuric acid attack.The dissolution rates of aluminum,iron,and titanium ions are 34.94%,17.05%,and 62.77%,respectively.The precipitation rate of Ti reaches 99%,and the loss of rare earth ions in the solution is less than 1%.Meanwhile,the results of a leaching kinetics analysis indicate that the leaching process of rare ions is controlled by diffusion.Precious metal ions such as iron and aluminum in the leaching solution can reduce the adsorption of rare earth ions by kaolinite.This study efficiently recovered rare earth ions under conditions of low calcination te mperature and direct water leaching,resulting in reduced energy consumption of the extraction process and acidity of the leaching solution.These findings provide a solid foundation for the further separation and extraction of rare earth ions.
基金National Natural Science Foundation of China(52104249)Liaoning Joint Fund General Support Program Project(2023-MSBA-126)the Fundamental Research Funds for the Central Universities(N2401019).
文摘Iron tailings are a common solid waste resource,posing serious environmental and spatial challenges.This study proposed a novel hydrogen-based reduction roasting(HRR)technology for the processing of iron tailings using a combined beneficiation and metallurgy approach.Pilot-cale experiment results indicated that under the gas composition of CO:H_(2)=1:3,and optimal roasting conditions at a reduction temperature of 520℃,the majority of weakly magnetic hematite transforms into strongly magnetic magnetite during the reduction process.Combining roasting products with a magnetic separation-grinding-magnetic selection process yields a final iron concentrate with a grade of 56.68%iron and a recovery rate of 86.54%.Theoretical calculations suggested the annual production value can reach 29.7 million USD and a reduction of 20.79 tons of CO_(2) emissions per year.This highlights that the use of HRR in conjunction with traditional beneficiation processes can effectively achieve comprehensive utilization of iron tailings,thereby reducing environmental impact.
基金supported by the National Natural Science Foundation of China(52204309,52374300 and 52174277)the Opening Foundation of State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization,China(2022P4FZG11A).
文摘The ammonium salt precipitation method is frequently utilized for extracting vanadium from the leaching solution obtained through sodium roasting of vanadium slag.However,Na^(+)and NH_(4)^(+)ions in the vanadium precipitation solution can not be effectively separated,leading to a large amount of ammonia-nitrogen wastewater which is difficult to treat.In this study,the manganese salt pretreatment process is used to extract vanadium from a sodium roasting leaching solution,enabling the separation of vanadium and sodium.The vanadium extraction product of manganese salt is dissolved in acid to obtain vanadium-containing leaching solution,then vanadium is extracted by hydrolysis and vanadium precipitation,and V_(2)O_(5)is obtained after impurity removal and calcination.The results show that the rate of vanadium extraction by manganese salt is 98.23%.The vanadium extraction product by manganese salt is Mn_(2)V_(2)O_(7),and its sodium content is only 0.167%.Additionally,the acid solubility of vanadium extraction products by manganese salt is 99.52%,and the vanadium precipitation rate of manganese vanadate solution is 92.34%.After the removal of manganese and calcination process,the purity of V_(2)O_(5)product reached 97.73%,with a mere 0.64%loss of vanadium.The Mn_(2)^(+)and NH_(4)^(+)ions in the solution after vanadium precipitation are separated by precipitation method,which reduces the generation of ammonia-nitrogen wastewater.This is conducive to the green and sustainable development of the vanadium industry.
基金Projects(52074069,52174314)supported by the National Natural Science Foundation of ChinaProject(E2021501029)supported by the Natural Science Foundation of Hebei Province,China+2 种基金Project(E2022501030)supported by the Natural Science Foundation-Steel,the Iron Foundation of Hebei Province,ChinaProject(22567627H)supported by Performance subsidy Fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province,ChinaProject(24464402D)supported by S&T Program of Hebei Province,China。
文摘The recovery of lithium from spent lithium-ion batteries(LIBs)is of great importance in addressing lithium shortages and environmental issues.In this study,a novel and clean process for selective separation of lithium from spent LiFePO_(4)cathode material by low temperature oxidative roasting and water leaching was proposed.The effect of several important factors,such as roasting temperature,roasting time,and molar ratio of ferric chloride(FeCl_(3)·6H_(2)O)to lithium iron phosphate(LFP),on the leaching efficiency of lithium and iron was systematically investigated by using single factor experimental method.The results show that approximately 97.1%lithium element was recovered by being converted to water-soluble LiCl at a roasting temperature 350℃,a roasting time 120 min and a FeCl_(3)·6H_(2)O/LFP molar ratio of 1:1,and iron element was enriched in the leaching residue in the form of insoluble FePO_(4).High-purity lithium carbonate products could be prepared from the leching solution by adding Na_(2)CO_(3) after removing iron.The establishment of new cleaning process can provide a scalable,environmentally friendly and simple way to recover valuable metals from spent LFP batteries.
文摘Chlorination roasting followed by water leaching process was used to extract lithium from lepidolite.The microstructure of the lepidolite and roasted materials were characterized by X-ray diffraction（XRD）.Various parameters including chlorination roasting temperature,time,type and amount of chlorinating agents were optimized.The conditional experiments indicate that the best mass ratio of lepidolite to NaCl to CaCl2 is 1：0.6：0.4 during the roasting process.The extraction of lithium reaches peak value of 92.86% at 880 °C,potassium,rubidium,and cesium 88.49%,93.60% and 93.01%,respectively.The XRD result indicates that the major phases of the product after roasting lepidolite with mixture of chlorinating agents（CaCl2 and NaCl） are SiO2,CaF2,KCl,CaSiO3,CaAl2Si2O8,NaCl and NaAlSi3O8.
基金Project (51074016) support by the National Natural Science Foundation of China
文摘High phosphorous oolitic hematite ore is one of typical intractable iron ores in China, and the conventional beneficiation methods are found to be impracticable to , remove phosphorus from the ore effectively. Better beneficiation index were gotten by direct reduction roasting with dephosphorization agent followed by two stages of grinding and magnetic separation. P content decreases from 0.82% in the raw ore to 0.06% in the magnetic concentrate, and the total iron grade increases from 43.65% to 90.23%, the recovery of iron can reach 87%. Mechanisms of phosphorus removal in the beneficiation of high phosphorous oolitic hematite ore by direct reduction roasting with dephosphorization agent were studied using XRD, SEM and EPMA. The results showed that about 20% of the apatite in the raw ore transferred into phosphorus and volatilized with the gas in the process of reduction roasting, while the rest 80% apatite was not involved in the reaction of generation of phosphorus, and remained as apatite in the roasted products, which was removed to tailings by grinding and magnetic separation. A small amount of phosphorus existed in the magnetic concentrate as apatite. The oolitic texture of raw ore was partly changed during roasting, resulting in the formation of nepheline in the reaction between the dephosphorization agent, SiO2 and Al2O3 in the raw ore, which greatly improved the liberation degree of minerals in the roasted products, and it was beneficial to the subsequent grinding and magnetic separation.
基金Project(NCET-10-0834) supported by the Program for New Century Excellent Talents in University,China
文摘A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of HaPO4 dosage, roasting temperature, and roasting time on TiO2 grade were investigated. A Ti-rich material containing 88.54% TiO2, 0.42% （CaO＋MgO） was obtained when finely ground titanium slag was roasted with 7.5% H3PO4 at 1000 ℃ for 2 h, followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h. The XRD patterns show that the product is titanium dioxide with a rutile structure. Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process. As a result, titanium components in titanium slag are transformed into TiO2 （futile） while impurities are transformed into acid-soluble phosphate and quartz.
基金Projects(5147414151174022)supported by the National Natural Science Foundation of China
文摘In order to investigate the oxidation roasting of molybdenite concentrate in pure oxygen atmosphere, experiments at 673, 723, 773, 873 and 973 K were carried out. The phase transitions and morphology evolutions of the samples obtained at different temperatures after reacting for different time were analyzed by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results showed that molybdenite concentrate was oxidized directly to Mo O3 in pure oxygen atmosphere. There were remarkable changes of the morphologies of products with the increase of the roasting temperature. It was also found that sintering phenomenon occurred during the roasting process in pure oxygen when the temperature was above 873 K. The composition of sintered sample was mainly comprised of Mo O3 and some unreacted Mo S2.
文摘H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.
