Bioleaching of vanadium from stone coal vanadium ore by Bacillus mucilaginosus:Influencing factors and mechanism

Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low grades.Therefore,the effective extraction and recovery of metallic vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore.Herein,Bacillus mucilaginosus was selected as the leaching strain.The vanadium leaching rate reached 35.5%after 20 d of bioleaching under optimal operating conditions.The cumulative vanadium leaching rate in the contact group reached 35.5%,which was higher than that in the noncontact group(9.3%).The metabolites of B.mucilaginosus,such as oxalic,tartaric,citric,and malic acids,dominated in bioleaching,accounting for 73.8%of the vanadium leaching rate.Interestingly,during leaching,the presence of stone coal stimulated the expression of carbonic anhydrase in bacterial cells,and enzyme activity increased by 1.335-1.905 U.Enzyme activity positively promoted the production of metabolite organic acids,and total organic acid content increased by 39.31 mg·L^(-1),resulting in a reduction of 2.51 in the pH of the leaching system with stone coal.This effect favored the leaching of vanadium from stone coal.Atomic force microscopy illustrated that bacterial leaching exacerbated corrosion on the surface of stone coal beyond 10 nm.Our study provides a clear and promising strategy for exploring the bioleaching mechanism from the perspective of microbial enzyme activity and metabolites.

Leaching of vanadium from stone coal with sulfuric acid

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℃, 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.

A new process of extracting vanadium from stone coal

A new process of extracting vanadium from the stone coal vanadium ore in Fangshankou, Dtmhuang area of Gansu Province, China was introduced. Various leaching experiments were carried out, and the results show that the vanadium ore in Fangshankou is difficult to process due to its high consumption of acid and the high leaching rate of impurities. However, the leaching rate can be up to 80% and the content of V2O5 in the residue can be between 0.22%-0.25% in the process of ore fme grinding→oxidation roasting→mixing and ripening→aqueous leaching→P2O4 solvent extraction→sulfuric acid stripping→oxidation and precipitation→decomposition by heat. Also, the quality of flaky V205 produced by this process can meet the requirements of GB3283--87. The total leaching rate of vanadium is 70%. Also, three types of wastes are easy to treat. The vanadium extraction process is better in relation to the aspect of environmental protection than the sodium method.

Calcified roasting-acid leaching process of vanadium from low-grade vanadium-containing stone coal

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.

Extracting vanadium from stone-coal by oxygen pressure acid leaching and solvent extraction

Vanadium extraction from stone-coal was investigated by oxygen pressure acid leaching and solvent extraction.The mineralogy of the stone-coal from Tongren City of Guizhou Province,China,was investigated by various determination methods. The effects of leaching time,leaching temperature,leaching agent concentration,leaching L/S ratio,granularity of material,additive consumption were investigated based on the mineralogy.The results show that under the conditions of leaching time of 3-4 h, temperature of 150℃,sulfuric acid consumption of 25%?30%,ratio of liquid to solid of 1.2:1,the granularity less than 0.074 mm, additive consumption of 3%-5%,and oxygen pressure of 1.2 MPa,and the vanadium leaching rate can be more than 92%by the method of two-step pressurized acid leaching.The powdery V2O5 product with 99.52%in V2O5 content is obtained by the flowsheet of acid recovery,removing iron by reduction process,solvent extraction,precipitating vanadium with ammonium water,and pyrolysis from the stone-coal oxygen pressure acid-leaching solution.The total recovery efficiency of vanadium is above 85%,which is more than 20%higher than that obtained in the conventional process.Furthermore,the new process does not cause air pollution since no HCl or Cl2 is released by calcination of the raw material.

Leaching vanadium by high concentration sulfuric acid from stone coal

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%.

Mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes from stone coal

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 ~C, 6 h, 1.5 ml.g-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 4- 0.05 by 200 g.L-1 lime milk, respectively. The solvent extraction experiments were carded 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 （Fe2Fs.7H20） and consume all ferric ions and a portion of ferrous ions. In adjusting pH value process, the massive impurities are decreased to form KA1SO4 and FeA1Fs. 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.

Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal

The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 moUL H2SO4 at 90℃ for 2 h. After the sample is roasted at 900℃ for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the Content of V（V） increases with the rise of roasting temperature from 600 to 900℃, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000℃. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.

Acid leaching of vanadium from roasted residue of stone coal

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.

Comparison of the mechanisms of microwave roasting and conventional roasting and of their effects on vanadium extraction from stone coal

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 tempera- ture, 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℃ for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vo1%, 1.5：1 mL.g-1, 95℃, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900℃ 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.

Bioleaching of vanadium from barren stone coal and its effect on the transition of vanadium speciation and mineral phase

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.

Effect of vanadium occurrence state on the choice of extracting vanadium technology from stone coal

The extraction technology of vanadium from stone coal by means of no-salt-roasting and dilute acid solution leaching treatment has the advantages of low pollution, low investment, as well as high vanadium leaching efficiency, which makes it the best technology for extending application. In the present study, the effects of vanadium occurrence state in stone coal, roasting temperature and additive agent on the leaching efficiency of vanadium were studied. The results indicate that the effect of vanadium occurrence state on the extracting vanadium technology is obvious. If the vanadium component in stone coal existed in amorphous phase form, this type of stone coal can be treated by no-slat-roasting and dilute acid solution leaching technology; while the vanadium-bearing crystalline phase existed in stone coal, the roasting additive must be added to destroy this crystalline form so as to acquire high vanadium leaching rate.

Desiliconisation of alkaline leaching solution of roasted stone coal with carbonation method

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.

电感耦合等离子体原子发射光谱(ICP-AES)法测定石煤钒矿石中钒、铁、钛的含量

研究一种快速准确测定石煤钒矿石中钒、铁、钛含量的方法对石煤钒矿检测行业的发展和石煤钒矿资源的开发利用、综合评价具有重要的意义。试样经过氧化钠在650℃完全熔融后保持1~3 min,取出冷却,热水浸提,盐酸酸化,定容稀释,选择V 292.402 nm、Fe 259.940 nm、Ti 334.941 nm为分析谱线,利用电感耦合等离子体原子发射光谱法(ICP-AES),建立了石煤钒矿石中同时测定钒、铁、钛含量的方法。优化了钒、铁、钛元素的分析谱线和背景校正模式,采用全程序样品空白稀释配制的校准曲线消除盐度钠基影响;研究了坩埚、熔剂种类、直接碱熔与灼烧-碱熔前处理方式、酸度效应的影响。结果表明:方法检出限为0.009%~0.019%,定量限为0.027%~0.057%;铁、钛、钒3种元素浓度在0.10~30.0μg/mL时,校准曲线线性回归方程的相关系数均大于0.9999;采用国家一级标准物质(GBW07876、GBW07877、GBW07878)进行验证,相对标准偏差(RSD,n=12)为0.49%~0.87%,且测定值与标准值吻合。方法具有快速简便、精密度好、准确度高、同时测定钒、铁、钛等优点,满足石煤钒矿石化学分析检测需求,且可为石煤钒矿化学分析标准方法的建立提供技术支撑。

N235从高碳石煤脱碳渣酸浸液中萃取钒的工艺研究

以某地高碳石煤脱碳渣经空白焙烧-酸浸后的浸出液为原料,采用萃取剂N235和反萃剂Na_(2)CO_(3)对钒萃取工艺和反萃取工艺进行了研究。结果表明,最佳萃取工艺参数为:萃原液pH值2.3、有机相组成为15%N235+5%仲辛醇+80%磺化煤油、相比(O/A)1∶4、萃取时间4 min、氧化剂氯酸钠用量为萃原液V_(2)O_(5)质量的0.05倍、萃取级数五级,钒萃取率达99%;最佳反萃工艺参数为:反萃剂Na_(2)CO_(3)溶液浓度8%、反萃相比(O/A)4∶1、反萃时间10 min、反萃级数三级,钒反萃取率可达99.50%。在最佳萃取和反萃取工艺条件下,钒浓度由4.25 g/L富集到68.50 g/L,且pH值为8.5,无需中和处理。对富钒液进一步沉钒、煅烧得到的最终产品V_(2)O_(5)品位为98.95%,且杂质含量低,满足行业标准YB/T 5304—2017中98级V_(2)O_(5)的要求。

用空白焙烧—酸浸工艺从石煤钒矿中提取钒

研究了采用空白焙烧—酸浸工艺从某石煤钒矿中提取钒,考察了磨矿细度、焙烧时间、焙烧温度、硫酸用量、助浸剂CaF_(2)用量、浸出温度、浸出时间和液固体积质量比对钒浸出率的影响。结果表明:适宜的空白焙烧条件为磨矿细度-74μm占70%,焙烧温度775℃和焙烧时间5 h;适宜的酸浸条件为硫酸用量10%、助浸剂CaF_(2)用量3%,液固体积质量比1.5∶1,浸出温度25℃和浸出时间1.5 h;适宜条件下,钒浸出率可达81.5%。

石煤钒矿低温硫酸熟化-水浸提钒工艺

这是一篇冶金工程领域的论文。以陕西某地含钒矿物为绢云母、伊利石的石煤钒矿为研究对象,采用低温硫酸熟化-水浸工艺提钒,考查了熟化温度、熟化时间、硫酸用量、氯化钠用量,浸出温度、浸出时间及浸出液固比对钒浸出率的影响。结果表明:向石煤钒矿中加入25%的硫酸、0.8%的氯化钠,在130℃下熟化8 h,熟化样品在浸出温度55℃、液固比1.5∶1的条件下浸出时间2 h,钒浸出率可达89%。这说明采用低温(130℃)硫酸熟化-水浸工艺提取石煤型钒矿是可行的。

江西某黏土型(石煤)钒矿工艺矿物学研究

通过偏光显微镜、扫描电子显微镜(矿物自动分析仪)、X射线能谱元素面分析等多种手段综合研究江西某地黏土型(石煤)钒矿中钒的赋存状态。样品为炭质页岩,V_(2)O_(5)含量为0.61%。黏土矿物主要为伊利石-2及伊利石,含量分别为41.35%和8.68%,石英含量38.14%,黄铁矿含量1.11%。样品具典型的显微鳞片结构,矿物粒度微细,黏土矿物主要为伊利石,呈显微鳞片状,片径主要为0.005 mm左右。常呈集合体状产出。晶粒结晶状态较模糊,且伊利石常与粉末状炭质混杂,界线不清,部分伊利石颜色较深,推测富含有机质。伊利石单体解离度较低,且几乎全部颗粒都处于解离程度小于25%的低自由度状态,连生关系较复杂,主要以石英的多相连生为主。矿石中未能发现钒的独立工业矿物,但显示黏土矿物(伊利石)与钒元素密切相关。钒主要以类质同象的形式存在于伊利石中,占比分配率99.8%,典型测点平均含钒含量为0.65%。根据矿石性质研究,建议选冶试验通过浮选脱除黄铁矿,然后通过擦洗—脱泥的方式对石英和黏土矿物进行分离,从而实现钒的富集。

浅析酒泉市石煤钒矿提钒工艺与环境污染治理

酒泉市石煤钒矿属于低热值石煤,矿石中钒价态以三价钒为主,采用循环流化床脱碳+空白焙烧浸出提钒工艺可有效解决低热值石煤不易燃烧问题,同时可实现热-电-钒工业联产。该工艺产生的环境污染主要为废气、废水和尾矿,废气经处理后可达标排放,废水经处理后全部回用,不外排;尾矿经固体废物属性鉴别,属于一般工业固体废物,可进入尾矿库堆存。

石煤提钒尾渣基钙长石烧结砖的烧结及重金属固化机理

这是一篇陶瓷及复合材料领域的论文。石煤提钒尾渣是一种危险的工业废弃物,综合利用石煤提钒尾渣具有重要的环保与经济意义。本研究以石煤提钒尾渣为主要原料制备了建筑用烧结砖,研究了烧成温度对样品结构和性能的影响规律,探究了Cu、V和Zn重金属浸出活性的钝化机理。结果表明:烧成温度显著影响烧结砖的相组成、显微结构和性能。适当提高烧成温度不仅有助于石英与原料中的碱性物质反应,生成富硅液相,提高样品的致密度,而且促进了黄长石向钙长石转变及莫来石生成。这些晶相与玻璃相互胶结,赋予制品较高的致密度和抗压强度。此外,提高烧成温度增大了制品中Cu、V和Zn的残渣态含量,减小了制品的孔径与孔容积,从而实现了Cu、V和Zn的固化。采用烧成温度为1 200℃,保温时间为3 h的工艺制度,制备出的建筑用烧结砖的各项性能均满足《烧结普通砖》(GB/T 5101—2003)中Mu25等级的要求,且制品的Cu、V、Zn重金属浸出浓度均低于标准值。研究结果为石煤提钒尾渣的综合利用提供了新的思路。