Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential...Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential for secondary utilization in composite preparation.We prepared SC-based composite PCMs with SC as a matrix,stearic acid (SA) as a PCM,and expanded graphite (EG) as an additive.The combined roasting and acid leaching treatment of raw SC was conducted to understand the effect of vanadium extraction on promoting loading capacity.Results showed that the combined treatment of roasting at 900℃ and leaching increased the SC loading of the composite by 6.2%by improving the specific surface area.The loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% EG.These data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed composite.The obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical compatibility.The SC-based composite has prospects in building applications exploiting the secondary utilization of minerals.展开更多
The purpose of this study is to apply process mineralogy as a practical tool to further understand and analyze the reasons for low leaching rates in the curing-leaching process of vanadium-bearing stone coal and to fi...The purpose of this study is to apply process mineralogy as a practical tool to further understand and analyze the reasons for low leaching rates in the curing-leaching process of vanadium-bearing stone coal and to find a solution or improvement to optimize the leaching index.Using vanadium-bearing stone coal with the V2O5 mass fraction of 0.88%as the research object,the effects of particle size,mineral composition,and sulfuric acid curing on the feed,intermediate,and final products of curing-leaching were analyzed.The main vanadium-bearing minerals in the feed samples included sericite/illite,montmorillonite,kaolinite,limonite,and schreyerite.Through the penetration depth analysis of sulfuric acid,the reason for the high vanadium content in the coarse leaching residue(0.205%V2O5)was found,mainly due to the poor curing effect and incomplete washing after screening.Therefore,thorough washing after sieving and further optimizing the curing process are necessary.The vanadium content of the fine leaching residue(0.078%)was low and the curing-leaching effect was good.However,the vanadium content in the thickened residue(0.296%)exceeded that in the fine leaching residue,which was attributed to the neutralization reaction in the#1 thickener.To solve this problem,the neutralization and thickening processes should be performed in separate equipment.The analysis and detection of key products is helpful for identifying problems and improving the curing-leaching circuit process.展开更多
The recovery of vanadium(V)from stone coal by bioleaching is a promising method.The bioleaching experiments and the biosorption experiments were carried out,aiming to explore the adsorption characteristics of Bacillus...The recovery of vanadium(V)from stone coal by bioleaching is a promising method.The bioleaching experiments and the biosorption experiments were carried out,aiming to explore the adsorption characteristics of Bacillus mucilaginosus(B.mucilaginosus)on the surface of vanadium-bearing stone coal,and the related mechanisms have been investigated.After bioleaching at 30℃ for 28 d,the cumulative leaching rate of V reached 60.2%.The biosorption of B.mucilaginosus on stone coal was affected by many factors.When the pH value of leaching system is 5.0,strong electrostatic attraction between bacteria and stone coal promoted biosorption.Bacteria in the logarithmic growth phase had mature and excellent biosorption properties.The initial bacterial concentration of 3.5×10^(8) CFU/mL was conducive to adhesion,with 38.9%adsorption rate and 3.6×10^(7) CFU/g adsorption quantity.The adsorption of B.mucilaginosus on the stone coal conformed to the Freundlich model and the pseudo-second-order kinetic model.Bacterial surface carried functional groups(-CH_(2),-CH_(3),-NH_(2),etc.),which were highly correlated with the adsorption behavior.In addition,biosorption changed the surface properties of stone coal,resulting in the isoelectric point(IEP)approaching the bacteria.The results could provide an effective reference for the adsorption laws of bacteria on minerals.展开更多
Through leaching from residue directly and leaching after a roasting treatment,respectively,the experimental research on sulfuric leaching of vanadium from residue of stone coal that came from power generation was con...Through leaching from residue directly and leaching after a roasting treatment,respectively,the experimental research on sulfuric leaching of vanadium from residue of stone coal that came from power generation was conducted.Factors which influence the leaching of vanadium such as concentration of sulfuric acid,leaching temperature,leaching time and liquid-to-solid ratio were investigated in both processes.In the process of direct leaching,to achieve a leaching rate of 74.49%,H2SO4 concentration of up to 5.4%,leaching temperature of 90℃and leaching time of 8 h were necessary reaction factors.The results show that after a roasting treatment at the optimum condition of 950℃at 1 h,76.88%vanadium can be leached under the experimental condition of 0.45% of H2SO4,30℃for 1 h with a liquid-to-solid ratio of 2 mL/g.Leaching after an oxidation roasting treatment is an efficient way to leach vanadium from the residue of stone coal,which has some advantages,such as high recovery,low economic cost and less impurities in leaching solution.展开更多
An effectively new technology of extracting vanadium from stone coals by high concentration sulfuric acid was researched. The effect of the concentration of sulfuric acid,leaching temperature,leaching time and helper ...An effectively new technology of extracting vanadium from stone coals by high concentration sulfuric acid was researched. The effect of the concentration of sulfuric acid,leaching temperature,leaching time and helper leaching agent on the extraction of vanadium was explored.The results show that the optimal conditions of extraction are as follows:the concentration of sulfuric acid is 6 mol/L,the ratio of liquid to solid is 3-1;the temperature is 90℃;the leaching time is 3-5 h,the diameter of the ore particle is less than 180μm,and the concentration of helper leaching agent R is 6%.Under these conditions,the extraction of vanadium can reach 95.86%.展开更多
The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the incr...The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the increase of flowrate of CO2 gas and reaction time.Reaction temperature and stirring speed have little effect on desilication rate,while influence the loss rate of vanadium significantly.Under the condition of reaction time of 2 h,reaction temperature of 95℃,stirring speed of 180 r/min,flowrate of CO2 gas of 60 mL/min and aging time of 2 h,desilication rate is more than 96%and the loss rate of vanadium is about 4.24%.The residue of desilication process can be processed for silicon materials,such as high-grade hydrated silica,which commonly known as white carbon black.In addition,with this carbonation method,leaching regents NaOH can be recycled by simple treatments.展开更多
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal.Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when ...The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal.Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 molL H 2 SO 4 at 90℃ for 2 h.After the sample is roasted at 900℃ for 2 h,the leaching rate of vanadium reaches the maximum,and more than 70% of vanadium can be leached.The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900℃,therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals.Some new phases,anorthite for example,form when the roasting temperature reaches 1000℃.A part of vanadium may be enwrapped in the sintered materials and newly formed phases,which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically.The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.展开更多
The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The lea...The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The leaching experiments were carried out under the conditions of 95 ℃, 6h, 1.5 mlg-1 , 15 vol % H2SO4 , and 5 % calcium fluoride (mass ratio of CaF2 to stone coal). The concentrations of hydrogen ion were adjusted from initial 1.82 and 4.79 mol L -1 to the pH of 1.80 ± 0.05 by 200 g L-1 lime milk, respectively. The solvent extraction experiments were carried out under the organic phase using 15 vol% D2EHPA, 5 vol% TBP, and 80 vol% sulfonated kerosene and O/A phase ratio of 1/4. The leaching rate of vanadium and six-stage countercurrent solvent extraction rate of vanadium can be remarkably improved from 66.71 to 92.97 % and 81.15 to 98.81 %, respectively, when calcium fluoride was added as aid-leaching reagent. In the leaching process, fluorine can enhance the breakage of the structure of vanadium-bearing minerals. Meanwhile, fluoride ion can combine with iron ion to generate acid-insoluble iron fluoride hydrate (Fe2F57H2O) and consume all ferric ions and a portion of ferrous ions. In adjusting pH value process, the massive impurities are decreased to form KAlSO4 and FeAlF5 . In solvent extraction process, fluorine can prevent the formation of ferric hydroxide colloids and eliminate the formed unstable ferric hydroxide colloids and the silicon-containing colloids to promote the sufficient contact between the aqueous phase and the organic phase and the sufficient reaction.展开更多
The effects of roasting, mass ratio of H2SO4 to stone coal, leaching temperature, liquid-to-solid ratio, grinding fineness of stone coal, and two-stage counter-current leaching on the vanadium leaching ratio were stud...The effects of roasting, mass ratio of H2SO4 to stone coal, leaching temperature, liquid-to-solid ratio, grinding fineness of stone coal, and two-stage counter-current leaching on the vanadium leaching ratio were studied. The results show that the vanadium leaching ratio of roasted stone coal through two-stage counter-current leaching can reach 65.1% at the mass ratio of H2SO4 to stone coal of 20%, leaching temperature of 95°C, leaching time of 30 h, liquid-to-solid ratio of 1.1 mL-g-1, and grinding fineness of 0.1 mm, which can serve as an experimental basis for the production of vanadium from stone coal.展开更多
The low-grade vanadium-containing stone coal used in this experiment was collected from Wuxi Country, Chongqing City, China. The experiment focused on the vanadium recovery from roasted residue through optimizing the ...The low-grade vanadium-containing stone coal used in this experiment was collected from Wuxi Country, Chongqing City, China. The experiment focused on the vanadium recovery from roasted residue through optimizing the process conditions of an effective and environmentally-friendly technology, named calcified roasting-sulfuric acid leaching technology. By single-factor experiments and orthogonal experiments, the effects of roasting temperature, roasting time, sulfuric acid concentration and leaching time on the leaching ratio of vanadium were analyzed. The results showed that the leaching ratio of vanadium reached 85.5% under the proper technological conditions of roasting temperature=950℃, roasting time=4 h, 40% concentration of sulfuric acid and leaching time=6 h.展开更多
Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is...Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is found that the optimum manganese reduction efficiency can be up to 98.97% under the conditions that the mass ratio of stone coal to pyrolusite is 3:1, the roasting temperature of stone coal is 1000℃, the roasting temperature of pyrolusite is 800℃, and the roasting time is 2 h. Other low-grade pyrolusite ores in China from Guangxi, Hunan, and Guizhou Provinces were tested and all these minerals responded well, giving～99% manganese reduction efficiency. Meanwhile, the reduction kinetic model has been established. It is confirmed that the reduction process is controlled by the interface chemical reaction. The apparent activation energy is 36.397 kJ/mol.展开更多
This paper investigates the leaching behavior of heavy metals(V,Pb,Cd,Cr,and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments.The results show that the dissolved concentra...This paper investigates the leaching behavior of heavy metals(V,Pb,Cd,Cr,and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments.The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb,Cd,and Cr were high in the early stage before decreasing.The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions.The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V,Pb,and As decreased in the order fine fraction > medium fraction > coarse fraction,and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction > coarse fraction > fine fraction and coarse fraction > medium fraction > fine fraction,respectively.The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V(17104.36 μg/kg) > As(609.41 μg/kg) > Pb(469.24 μg/kg) > Cr(56.35 μg/kg) > Cd(27.52 μg/kg),and the dissolution rates decreased in the order As(2.96%) > Pb(0.93%) > V(0.35%) > Cd(0.25%) > Cr(0.01%).The specific surface area,pore size of the stone coal waste rocks,and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks.Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model.The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks.展开更多
Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to...Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to investigate the effects of roasting temperature, roasting time, H2SO4 concentration, and leaching time on vanadium extraction. The results show that the vanadium leaching efficiency is 84% when the sample is roasted at 800°C for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vol%, 1.5:1 m L·g-1, 95°C, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900°C for 60 min is just 71% under the same leaching conditions. Scanning electron microscopy(SEM) analysis shows that the microwave roasted samples contain more cracks and that the particles are more porous compared to the conventionally roasted samples. According to the results of X-ray diffraction(XRD) and Fourier-transform infrared(FTIR) analyses, neither of these roasting methods could completely destroy the mica lattice structure under the experimental conditions; however, both methods deformed the muscovite structure and facilitated the leaching process. Comparing with conventional roasting, microwave roasting causes a greater deformation of the mineral structure at a lower temperature for a shorter roasting time.展开更多
In order to reduce the pollution of Cl2 and HCl released during extracting vanadium from stone coal by sodium chloride roasting, a modified salt-roasting process was proposed by adding calcined lime in roasting proces...In order to reduce the pollution of Cl2 and HCl released during extracting vanadium from stone coal by sodium chloride roasting, a modified salt-roasting process was proposed by adding calcined lime in roasting process followed by H2SO4 leaching. The effects of parameters including roasting temperature, roasting time, addition mass ratio of NaCl, calcined lime upon leaching rate of vanadium and curing rate of chlorine were investigated, and the effects of leaching time and leaching temperature on leaching rate of vanadium were also studied. The results show that the vanadium leaching rate and the curing rate of chlorine are 67.3% and 51.5% (mass fraction), respectively, at roasting temperature of 750 °C, roasting time of 4 h, 15% sodium chloride and 8% (mass fraction) calcined lime, leaching temperature of room temperature, and leaching time of 4 h.展开更多
This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including th...This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including the initial p H value, initial Fe^(2+) concentration, solid load, and inoculum quantity were examined. The results revealed that 48.92 wt% of the vanadium was extracted through bioleaching under optimal conditions. Comparatively, the chemical leaching yield(H_2SO_4, pH 2.0) showed a slower and milder increase in vanadium yield. The vanadium bioleaching yield was 35.11 wt% greater than the chemical leaching yield. The Community Bureau of Reference(BCR) sequential extraction results revealed that 88.62 wt% of vanadium existed in the residual fraction. The bacteria substantially changed the distribution of the vanadium speciation during the leaching process, and the residual fraction decreased to 48.44 wt%. The X-ray diffraction(XRD) and Fourier transform infrared(FTIR) results provided evidence that the crystal lattice structure of muscovite was destroyed by the bacteria.展开更多
Low recovery rate,high energy consumption and serious pollution are existed in traditional processes of vanadium extraction.To seek a new process with high recovery rate,low energy consumption and less pollution disch...Low recovery rate,high energy consumption and serious pollution are existed in traditional processes of vanadium extraction.To seek a new process with high recovery rate,low energy consumption and less pollution discharge is of great significance.Microwave-aided roasting for vanadium extraction is an environmentally-friendly technology.Non-pollution roasting processes with additives following sodium carbonate and potassium carbonate,under microwave irradiation were investigated with stone coal.The valence variation of vanadium in oxidation roasting of the vanadium bearing stone coal was studied.The results showed that the oxidation process of vanadium was a stepwise process following V(Ⅲ)→V(Ⅳ)→V(Ⅴ).The roasted stone coal was characterized by XRD,SEM.Factors associated with extraction rate were investigated following roasting temperature,roasting time,microwave power,and amount of roasting additive.Comparing with conventional roasting process,the recovery rate was higher without air pollution.展开更多
The high calcium type stone coal from Hubei province was leached by water and dilute acid separately after being roasted with different dosage of Na Cl. The water leaching rate of vanadium(WLRV) was low and only 26.8%...The high calcium type stone coal from Hubei province was leached by water and dilute acid separately after being roasted with different dosage of Na Cl. The water leaching rate of vanadium(WLRV) was low and only 26.8% of vanadium can be leached by water when 4% Na Cl was added, but the acid leaching rate of vanadium(ALRV) was relatively high. Calcium in the high calcium type stone coal is greatly superfl uous relative to vanadium, hence, the calcium reacts with vanadium to form Ca(VO3)2, Ca2V2O7 and Ca3(VO4)2orderly during the stone coal roasting process and high temperature is beneficial to the reactions between calcium and vanadium, which was validated by simulated reactions between pure calcium carbonate and vanadium pentoxide. These calcium vanadates are all water insoluble but acid soluble and this causes the low WLRV and relatively high ALRV. After calcium removal by HCl, the WLRV is highly enhanced and reaches about 50% when only 2% Na Cl was added. If the HCl content is too high, the stone coal is easily sintered and the formed glass structure can enwrap vanadium, which leads the WLRV to decline. Single water leaching process is not appropriate to extract vanadium from high calcium type stone coal.展开更多
Stone coal is a special resource, because it is associated with a variety of rare metal elements. The elemental geochemical characteristics of stone coal can provide useful information for the study of its formation a...Stone coal is a special resource, because it is associated with a variety of rare metal elements. The elemental geochemical characteristics of stone coal can provide useful information for the study of its formation and evolution history. The content of rare earth elements in stone coal has been the focus of attention. Stone coal is widely distributed in southern Shaanxi province of China. In order to study the content and distribution of rare earth elements in stone coal, and provide a plan for the comprehensive development and utilization of stone coal, this study tested the rare earth elements content of stone coal, parting and coal ash samples, respectively, compared the content of rare earth elements in stone coal, parting, coal ash with the mean value of China coal, the mean value of world coal and the abundance value of upper crust, and discussed the features of rare earth elements content in different types of samples in southern Shaanxi province of China. The average contents of rare earth elements in the samples of stone coal, parting and coal ash were calculated, and the enrichment coefficients of the samples with the mean value of China coal, the mean value of world coal and the abundance value of upper crust were listed. The distribution rules and characteristics of the contents of rare earth elements in different types of samples in southern Shaanxi province of China were summarized.展开更多
基金financially supported by the National Natural Science Foundation of China, China (Nos. 52274252 and 51874047)the Special Fund for the Construction of Innovative Provinces in Hunan Province, China (No. 2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars, China (No. kq1802007)。
文摘Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential for secondary utilization in composite preparation.We prepared SC-based composite PCMs with SC as a matrix,stearic acid (SA) as a PCM,and expanded graphite (EG) as an additive.The combined roasting and acid leaching treatment of raw SC was conducted to understand the effect of vanadium extraction on promoting loading capacity.Results showed that the combined treatment of roasting at 900℃ and leaching increased the SC loading of the composite by 6.2%by improving the specific surface area.The loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% EG.These data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed composite.The obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical compatibility.The SC-based composite has prospects in building applications exploiting the secondary utilization of minerals.
基金supported by the National Key Research and Development Program of China(No.2020YFC1909704)the National Natural Science Foundation of China(Nos.51904222 and 52074068)+1 种基金the Shaanxi Innovation Capacity Support Plan(2020KJXX-053)the Shaanxi Natural Science Basic Research Program(No.2019JQ-468).
文摘The purpose of this study is to apply process mineralogy as a practical tool to further understand and analyze the reasons for low leaching rates in the curing-leaching process of vanadium-bearing stone coal and to find a solution or improvement to optimize the leaching index.Using vanadium-bearing stone coal with the V2O5 mass fraction of 0.88%as the research object,the effects of particle size,mineral composition,and sulfuric acid curing on the feed,intermediate,and final products of curing-leaching were analyzed.The main vanadium-bearing minerals in the feed samples included sericite/illite,montmorillonite,kaolinite,limonite,and schreyerite.Through the penetration depth analysis of sulfuric acid,the reason for the high vanadium content in the coarse leaching residue(0.205%V2O5)was found,mainly due to the poor curing effect and incomplete washing after screening.Therefore,thorough washing after sieving and further optimizing the curing process are necessary.The vanadium content of the fine leaching residue(0.078%)was low and the curing-leaching effect was good.However,the vanadium content in the thickened residue(0.296%)exceeded that in the fine leaching residue,which was attributed to the neutralization reaction in the#1 thickener.To solve this problem,the neutralization and thickening processes should be performed in separate equipment.The analysis and detection of key products is helpful for identifying problems and improving the curing-leaching circuit process.
基金supported by the National Natural Science Foundation of China(No.51874018)。
文摘The recovery of vanadium(V)from stone coal by bioleaching is a promising method.The bioleaching experiments and the biosorption experiments were carried out,aiming to explore the adsorption characteristics of Bacillus mucilaginosus(B.mucilaginosus)on the surface of vanadium-bearing stone coal,and the related mechanisms have been investigated.After bioleaching at 30℃ for 28 d,the cumulative leaching rate of V reached 60.2%.The biosorption of B.mucilaginosus on stone coal was affected by many factors.When the pH value of leaching system is 5.0,strong electrostatic attraction between bacteria and stone coal promoted biosorption.Bacteria in the logarithmic growth phase had mature and excellent biosorption properties.The initial bacterial concentration of 3.5×10^(8) CFU/mL was conducive to adhesion,with 38.9%adsorption rate and 3.6×10^(7) CFU/g adsorption quantity.The adsorption of B.mucilaginosus on the stone coal conformed to the Freundlich model and the pseudo-second-order kinetic model.Bacterial surface carried functional groups(-CH_(2),-CH_(3),-NH_(2),etc.),which were highly correlated with the adsorption behavior.In addition,biosorption changed the surface properties of stone coal,resulting in the isoelectric point(IEP)approaching the bacteria.The results could provide an effective reference for the adsorption laws of bacteria on minerals.
基金Project(50974133)supported by the National Natural Science of Chinaproject(08zxgk06)supported by the Opening Foundation of Key Laboratory of Solid Waste Treatment and Resource Recycle(SWUST),Ministry of Education,China
文摘Through leaching from residue directly and leaching after a roasting treatment,respectively,the experimental research on sulfuric leaching of vanadium from residue of stone coal that came from power generation was conducted.Factors which influence the leaching of vanadium such as concentration of sulfuric acid,leaching temperature,leaching time and liquid-to-solid ratio were investigated in both processes.In the process of direct leaching,to achieve a leaching rate of 74.49%,H2SO4 concentration of up to 5.4%,leaching temperature of 90℃and leaching time of 8 h were necessary reaction factors.The results show that after a roasting treatment at the optimum condition of 950℃at 1 h,76.88%vanadium can be leached under the experimental condition of 0.45% of H2SO4,30℃for 1 h with a liquid-to-solid ratio of 2 mL/g.Leaching after an oxidation roasting treatment is an efficient way to leach vanadium from the residue of stone coal,which has some advantages,such as high recovery,low economic cost and less impurities in leaching solution.
基金Project(2007ZDGC-11)supported by"13115"Science and Technique Innovation Program of Shaanxi Province,ChinaProject(QN0918)supported by Science Fund for Young Scholars of Xi’an University of Architecture and Technology,China
文摘An effectively new technology of extracting vanadium from stone coals by high concentration sulfuric acid was researched. The effect of the concentration of sulfuric acid,leaching temperature,leaching time and helper leaching agent on the extraction of vanadium was explored.The results show that the optimal conditions of extraction are as follows:the concentration of sulfuric acid is 6 mol/L,the ratio of liquid to solid is 3-1;the temperature is 90℃;the leaching time is 3-5 h,the diameter of the ore particle is less than 180μm,and the concentration of helper leaching agent R is 6%.Under these conditions,the extraction of vanadium can reach 95.86%.
基金Project(50974133)supported by the National Natural Science Foundation of China
文摘The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the increase of flowrate of CO2 gas and reaction time.Reaction temperature and stirring speed have little effect on desilication rate,while influence the loss rate of vanadium significantly.Under the condition of reaction time of 2 h,reaction temperature of 95℃,stirring speed of 180 r/min,flowrate of CO2 gas of 60 mL/min and aging time of 2 h,desilication rate is more than 96%and the loss rate of vanadium is about 4.24%.The residue of desilication process can be processed for silicon materials,such as high-grade hydrated silica,which commonly known as white carbon black.In addition,with this carbonation method,leaching regents NaOH can be recycled by simple treatments.
基金financially supported by the National Key Technologies R&D Program of China(Nos.2011BAB05B01 and 2011BAB05B04)the Exclusive Research Fund of Environmental Protection for the Commonweal of China(No.201009013)
文摘The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal.Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 molL H 2 SO 4 at 90℃ for 2 h.After the sample is roasted at 900℃ for 2 h,the leaching rate of vanadium reaches the maximum,and more than 70% of vanadium can be leached.The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900℃,therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals.Some new phases,anorthite for example,form when the roasting temperature reaches 1000℃.A part of vanadium may be enwrapped in the sintered materials and newly formed phases,which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically.The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.
基金financially supported by the Key Science and Technology Support Program (No. 2011BAB05B01) from the Ministry of ScienceTechnology of China and the Special Science and Technology Program (No. 201009013) from the Ministry of Environmental Protection of China
文摘The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The leaching experiments were carried out under the conditions of 95 ℃, 6h, 1.5 mlg-1 , 15 vol % H2SO4 , and 5 % calcium fluoride (mass ratio of CaF2 to stone coal). The concentrations of hydrogen ion were adjusted from initial 1.82 and 4.79 mol L -1 to the pH of 1.80 ± 0.05 by 200 g L-1 lime milk, respectively. The solvent extraction experiments were carried out under the organic phase using 15 vol% D2EHPA, 5 vol% TBP, and 80 vol% sulfonated kerosene and O/A phase ratio of 1/4. The leaching rate of vanadium and six-stage countercurrent solvent extraction rate of vanadium can be remarkably improved from 66.71 to 92.97 % and 81.15 to 98.81 %, respectively, when calcium fluoride was added as aid-leaching reagent. In the leaching process, fluorine can enhance the breakage of the structure of vanadium-bearing minerals. Meanwhile, fluoride ion can combine with iron ion to generate acid-insoluble iron fluoride hydrate (Fe2F57H2O) and consume all ferric ions and a portion of ferrous ions. In adjusting pH value process, the massive impurities are decreased to form KAlSO4 and FeAlF5 . In solvent extraction process, fluorine can prevent the formation of ferric hydroxide colloids and eliminate the formed unstable ferric hydroxide colloids and the silicon-containing colloids to promote the sufficient contact between the aqueous phase and the organic phase and the sufficient reaction.
基金This work was financially supported by the Science Foundation of Central South University (No.76112037)the Postdoctoral Science Foundation of Central South University.
基金supported by the Science Foundation of Central South University (No. 76112037)the Postdoctoral Science Foundation of Central South University.
文摘The effects of roasting, mass ratio of H2SO4 to stone coal, leaching temperature, liquid-to-solid ratio, grinding fineness of stone coal, and two-stage counter-current leaching on the vanadium leaching ratio were studied. The results show that the vanadium leaching ratio of roasted stone coal through two-stage counter-current leaching can reach 65.1% at the mass ratio of H2SO4 to stone coal of 20%, leaching temperature of 95°C, leaching time of 30 h, liquid-to-solid ratio of 1.1 mL-g-1, and grinding fineness of 0.1 mm, which can serve as an experimental basis for the production of vanadium from stone coal.
基金the Scientific Research Foundation of State Key Lab.of Coal Mine Disaster Dynamics and Control(2011AD105827-MS201206)Scientific&Technologic Program for the Bureau of Land Resources and Housing Management of Chongqing
文摘The low-grade vanadium-containing stone coal used in this experiment was collected from Wuxi Country, Chongqing City, China. The experiment focused on the vanadium recovery from roasted residue through optimizing the process conditions of an effective and environmentally-friendly technology, named calcified roasting-sulfuric acid leaching technology. By single-factor experiments and orthogonal experiments, the effects of roasting temperature, roasting time, sulfuric acid concentration and leaching time on the leaching ratio of vanadium were analyzed. The results showed that the leaching ratio of vanadium reached 85.5% under the proper technological conditions of roasting temperature=950℃, roasting time=4 h, 40% concentration of sulfuric acid and leaching time=6 h.
基金financially supported by the National Natural Science Foundation of China (Nos. 21176026 and 21176242)the National High Technology Research and Development Program of China (No. 2012AA062401)+2 种基金the National Key Technology R&D Program of China (Nos.2012BAB07B05 and 2012BAB14B05)China Ocean Mineral resources R&D Association (No. DY125-15-T-08)the Fundamental Reserarch Funds for the Central Universities of China (No. FRT-TP-09-002B)
文摘Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is found that the optimum manganese reduction efficiency can be up to 98.97% under the conditions that the mass ratio of stone coal to pyrolusite is 3:1, the roasting temperature of stone coal is 1000℃, the roasting temperature of pyrolusite is 800℃, and the roasting time is 2 h. Other low-grade pyrolusite ores in China from Guangxi, Hunan, and Guizhou Provinces were tested and all these minerals responded well, giving～99% manganese reduction efficiency. Meanwhile, the reduction kinetic model has been established. It is confirmed that the reduction process is controlled by the interface chemical reaction. The apparent activation energy is 36.397 kJ/mol.
基金financially supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China (No.2015ZX07205003)
文摘This paper investigates the leaching behavior of heavy metals(V,Pb,Cd,Cr,and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments.The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb,Cd,and Cr were high in the early stage before decreasing.The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions.The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V,Pb,and As decreased in the order fine fraction > medium fraction > coarse fraction,and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction > coarse fraction > fine fraction and coarse fraction > medium fraction > fine fraction,respectively.The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V(17104.36 μg/kg) > As(609.41 μg/kg) > Pb(469.24 μg/kg) > Cr(56.35 μg/kg) > Cd(27.52 μg/kg),and the dissolution rates decreased in the order As(2.96%) > Pb(0.93%) > V(0.35%) > Cd(0.25%) > Cr(0.01%).The specific surface area,pore size of the stone coal waste rocks,and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks.Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model.The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks.
基金financially supported by the Research Project from the Chinese Ministry of Education (No. 213025A)
文摘Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to investigate the effects of roasting temperature, roasting time, H2SO4 concentration, and leaching time on vanadium extraction. The results show that the vanadium leaching efficiency is 84% when the sample is roasted at 800°C for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vol%, 1.5:1 m L·g-1, 95°C, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900°C for 60 min is just 71% under the same leaching conditions. Scanning electron microscopy(SEM) analysis shows that the microwave roasted samples contain more cracks and that the particles are more porous compared to the conventionally roasted samples. According to the results of X-ray diffraction(XRD) and Fourier-transform infrared(FTIR) analyses, neither of these roasting methods could completely destroy the mica lattice structure under the experimental conditions; however, both methods deformed the muscovite structure and facilitated the leaching process. Comparing with conventional roasting, microwave roasting causes a greater deformation of the mineral structure at a lower temperature for a shorter roasting time.
基金Project(2007GH001) supported by Development and Reform Commission of Guizhou Province, China
文摘In order to reduce the pollution of Cl2 and HCl released during extracting vanadium from stone coal by sodium chloride roasting, a modified salt-roasting process was proposed by adding calcined lime in roasting process followed by H2SO4 leaching. The effects of parameters including roasting temperature, roasting time, addition mass ratio of NaCl, calcined lime upon leaching rate of vanadium and curing rate of chlorine were investigated, and the effects of leaching time and leaching temperature on leaching rate of vanadium were also studied. The results show that the vanadium leaching rate and the curing rate of chlorine are 67.3% and 51.5% (mass fraction), respectively, at roasting temperature of 750 °C, roasting time of 4 h, 15% sodium chloride and 8% (mass fraction) calcined lime, leaching temperature of room temperature, and leaching time of 4 h.
基金financially supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2015ZX07205003)
文摘This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including the initial p H value, initial Fe^(2+) concentration, solid load, and inoculum quantity were examined. The results revealed that 48.92 wt% of the vanadium was extracted through bioleaching under optimal conditions. Comparatively, the chemical leaching yield(H_2SO_4, pH 2.0) showed a slower and milder increase in vanadium yield. The vanadium bioleaching yield was 35.11 wt% greater than the chemical leaching yield. The Community Bureau of Reference(BCR) sequential extraction results revealed that 88.62 wt% of vanadium existed in the residual fraction. The bacteria substantially changed the distribution of the vanadium speciation during the leaching process, and the residual fraction decreased to 48.44 wt%. The X-ray diffraction(XRD) and Fourier transform infrared(FTIR) results provided evidence that the crystal lattice structure of muscovite was destroyed by the bacteria.
基金supported by the National High Technology Research and Development Program of China(2008AA031202)Major Science&Technology of Chongqing(CSTC2008AA4026)foundation of Chongqing University for Young Talents to Promote the Innovative Force(qnjj2008-7)
文摘Low recovery rate,high energy consumption and serious pollution are existed in traditional processes of vanadium extraction.To seek a new process with high recovery rate,low energy consumption and less pollution discharge is of great significance.Microwave-aided roasting for vanadium extraction is an environmentally-friendly technology.Non-pollution roasting processes with additives following sodium carbonate and potassium carbonate,under microwave irradiation were investigated with stone coal.The valence variation of vanadium in oxidation roasting of the vanadium bearing stone coal was studied.The results showed that the oxidation process of vanadium was a stepwise process following V(Ⅲ)→V(Ⅳ)→V(Ⅴ).The roasted stone coal was characterized by XRD,SEM.Factors associated with extraction rate were investigated following roasting temperature,roasting time,microwave power,and amount of roasting additive.Comparing with conventional roasting process,the recovery rate was higher without air pollution.
基金Funded by the Fundamental Research Funds for Central Universities(WUT:2013-IV-001)the Ministry of Education of the People's Republic of China(No.20120143120007)
文摘The high calcium type stone coal from Hubei province was leached by water and dilute acid separately after being roasted with different dosage of Na Cl. The water leaching rate of vanadium(WLRV) was low and only 26.8% of vanadium can be leached by water when 4% Na Cl was added, but the acid leaching rate of vanadium(ALRV) was relatively high. Calcium in the high calcium type stone coal is greatly superfl uous relative to vanadium, hence, the calcium reacts with vanadium to form Ca(VO3)2, Ca2V2O7 and Ca3(VO4)2orderly during the stone coal roasting process and high temperature is beneficial to the reactions between calcium and vanadium, which was validated by simulated reactions between pure calcium carbonate and vanadium pentoxide. These calcium vanadates are all water insoluble but acid soluble and this causes the low WLRV and relatively high ALRV. After calcium removal by HCl, the WLRV is highly enhanced and reaches about 50% when only 2% Na Cl was added. If the HCl content is too high, the stone coal is easily sintered and the formed glass structure can enwrap vanadium, which leads the WLRV to decline. Single water leaching process is not appropriate to extract vanadium from high calcium type stone coal.
文摘Stone coal is a special resource, because it is associated with a variety of rare metal elements. The elemental geochemical characteristics of stone coal can provide useful information for the study of its formation and evolution history. The content of rare earth elements in stone coal has been the focus of attention. Stone coal is widely distributed in southern Shaanxi province of China. In order to study the content and distribution of rare earth elements in stone coal, and provide a plan for the comprehensive development and utilization of stone coal, this study tested the rare earth elements content of stone coal, parting and coal ash samples, respectively, compared the content of rare earth elements in stone coal, parting, coal ash with the mean value of China coal, the mean value of world coal and the abundance value of upper crust, and discussed the features of rare earth elements content in different types of samples in southern Shaanxi province of China. The average contents of rare earth elements in the samples of stone coal, parting and coal ash were calculated, and the enrichment coefficients of the samples with the mean value of China coal, the mean value of world coal and the abundance value of upper crust were listed. The distribution rules and characteristics of the contents of rare earth elements in different types of samples in southern Shaanxi province of China were summarized.
