二氧化锰对石煤钒矿酸性浸出的影响

采用湘西地区的石煤钒矿为研究对象,石煤中+3,+4,+5价钒分布分别为75.67%,17.85%和6.48%,硅酸盐含量较高,属高硅石煤矿。在传统直接酸浸工艺的基础上,添加少量氧化剂二氧化锰,考察了二氧化锰的用量、液固比、浸出温度、浸出时间、硫酸体积浓度等因素对钒浸出率的影响。单因素实验和正交试验结果表明:加入少量二氧化锰能协同H+破坏石煤结构,大大提高石煤中钒的浸出率;在二氧化锰用量为2%、液固比为1∶1、浸出时间为13 h、硫酸体积浓度为25%和浸出温度为95℃的条件下,钒浸出率达到97.2%,其中硫酸体积浓度对石煤湿法提钒影响最大。和直接酸浸工艺相比,钒的浸出率提高40%以上;与传统的钠化焙烧工艺相比,钒的浸出率提高40%以上,完全消除了焙烧过程中所产生的烟气污染;本实验采用氧化酸浸提钒技术,不经焙烧过程,不产生烟气污染,节约能源,且能大幅度提高钒的浸出率,实现资源的充分利用,具有较好的应用前景。     

石煤钒矿碳酸钠混合焙烧-浸出实验研究

以湖南某地的石煤钒矿为原料,通过实验研究了Na2CO3作为添加剂和浸出剂对石煤钒矿焙烧-浸出效果的影响。实验结果表明,钒的浸出率随焙烧温度、焙烧时间和Na2CO3添加量不同而变化;该地石煤钒矿最佳焙烧条件是:焙烧温度为800℃,焙烧时间为2h,Na2CO3添加量为矿量的2%。     

石煤钒矿浓酸熟化浸出工艺优化

针对目前石煤钒矿焙烧效果差,全湿法工艺流程缺陷多等问题,以湖南某地石煤钒矿为研究对象,在前期对含钒石煤矿进行浓酸熟化浸出研究的基础上,采用保湿处理对石煤钒矿浓酸熟化浸出过程进行强化,重点考察了熟化时间、硫酸用量、熟化温度、拌水量工艺参数对钒浸出率的影响,同时对石煤中含钒物相在熟化过程中变化进行了研究。试验结果表明:熟化过程中控制相对湿度在65%左右进行保湿处理,在熟化时间8.5 h、硫酸用量20%、熟化温度120℃、拌水量10%的最佳熟化条件下,钒浸出率达到93.9%;而在相同酸用量、熟化温度和拌水量的条件下,采用常规浓酸熟化法熟化5.5 h,钒浸出率只有78.0%。保湿处理极大提高了石煤钒矿浓酸熟化浸出工艺的钒浸出率,起到了显著地强化作用。由含钒物相分析可知,在熟化过程中含钒云母物相被有效破坏,水浸过程中云母结构没有继续分解,只是可溶钒的溶出过程。本实验采用保湿浓酸熟化浸出技术,避免了高耗能、高污染的焙烧过程,提钒效率高,是一种经济环保的石煤提钒新工艺,具有良好的工业应用前景。     

三种石煤钒矿浸出行为的对比研究

以江西省修水县、江西省彭泽县和湖北省通山县的三种石煤钒矿为对象,研究了直接酸浸工艺和空白焙烧-酸浸工艺对三种石煤钒矿中钒浸出行为的影响。结果表明:在温度95℃、浸出时间4h、液固比1∶1、H2SO4体积分数15%和CaF2质量分数5%的浸出条件下,三种石煤钒矿在直接酸浸工艺中的钒浸出率分别为92.39%、74.10%和40.53%,而在空白焙烧-酸浸工艺中的钒浸出率则分别为85.53%、90.78%和41.59%。石煤钒矿中钒、铁的赋存形式以及方解石等耗酸物质的含量均对钒浸出率有很大影响。空白焙烧能使炭质钒转变为较易溶出的游离钒氧化物,并能破坏云母类含钒矿物而促进钒的浸出,但同时也可能使黄铁矿等非耗酸矿物转变成赤铁矿等耗酸矿物而阻碍钒的浸出。上述三种石煤中的钒均主要赋存于云母类铝硅酸盐矿物中,根据原矿的不同特性需采用不同的提钒工艺:江西修水石煤钒矿宜采用直接浸出工艺,江西彭泽石煤钒矿宜采用空白焙烧-酸浸工艺,湖北通山石煤钒矿需采用其他提钒工艺。     

石煤钒矿浸出过程研究与动力学分析

以湖南某地的石煤钒矿石为原料,进行空白氧化焙烧得到焙烧矿粉,使用H2 SO4浸出以确定石煤钒矿中钒的含量.探讨了硫酸浓度、固液比、浸出时间、浸出温度对钒浸出率的影响.结果表明:使用4 mol/L的硫酸作为浸出剂,在温度为95℃、液固比为4∶1的条件下进行浸出8h,通过计算可得此时钒的浸出率为88.3％.石煤钒矿的浸出过...     

从某低品位石煤钒矿中浸出钒的工艺研究

研究了从某低品位石煤钒矿中浸出钒,主要考察了硫酸直接浸出、氧化焙烧—酸浸、氧化焙烧—碱浸和钙化焙烧—碳酸钠浸出等工艺对钒浸出率的影响。结果表明:造球氧化焙烧—酸浸流程工艺指标较好;在焙烧温度850℃、焙烧时间2h、酸用量为矿石质量60%条件下浸出6h,五氧化二钒浸出率达62.5%。     

钙质复合添加剂对石煤提钒焙烧效果的影响

以湖北某云母型含钒石煤为原料,研究了不同钙质添加剂对石煤焙烧效果的影响。在此基础上选取CaO、CaF_2组成复合添加剂,考察了复合添加剂配比、焙烧温度及焙烧时间对钒浸出率的影响,同时对石煤焙烧熟料进行了扫描电镜、X射线衍射、热力学分析。结果表明,石煤在添加6%CaO+4%CaF_2、焙烧温度850℃、焙烧时间90min的条件下焙烧,焙烧熟料按照液固比3∶1(mL/g)加入体积分数20%的硫酸、95℃浸出2h,钒浸出率可达91.73%。XRD和热力学分析表明,CaF_2参与了化学反应,添加剂加入后云母结构在焙烧过程中被有效的破坏,为钒的解离提供了基础;CaO对V_2O_5有很好的亲活力,焙烧可以促进钒酸钙的生成,有利于钒的浸出。     

云母型含钒石煤灰渣空白焙烧提钒试验研究

为探究云母型含钒石煤空白焙烧提钒工艺的可行性,以西北某地云母型含钒石煤为研究对象,对石煤进行循环流化床燃烧利用其热能后,通过细磨技术对石煤灰渣进行预处理,同时,针对灰渣粒度、焙烧温度、焙烧时间、空气流量等焙烧因素对钒转浸率的影响作用,对细磨处理后的灰渣进行了空白焙烧的相关试验研究。研究结果表明:焙烧温度对钒转浸率的提高有显著影响,焙烧过程中,较低的焙烧温度不能有效破坏钒云母晶格结构,当焙烧温度足以有效破坏云母晶格结构时,若低价钒不能被氧化成高价态含钒化合物,钒也难以浸出;焙烧过程中,氧化性气氛的存在一方面将释放出来的低价钒氧化成高价态含钒化合物,同时有助于促进含钒云母晶格中钒的释放;经细磨预处理的石煤灰渣进行高温空白焙烧后,在常温(20℃)、低酸(0.54 mol·L-1H2SO4)、无助浸剂、静置2 h等酸浸条件下进行酸浸,钒转浸率可达83.81%,这表明对云母型含钒石煤进行空白焙烧提钒是可行的。     

硫酸铵焙烧法从石煤钒矿中提取钒和铝的试验研究

采用在石煤钒矿流化床燃烧灰渣中加入硫酸铵进行焙烧,再用稀硫酸浸出焙砂的工艺,进行了从石煤钒矿中提取钒和铝的试验,考察了硫酸铵添加量、混磨时间、焙烧温度、焙烧时间等对钒、铝浸出率的影响。在采用优化工艺参数的条件下,钒的浸出率大于88%,铝的浸出率达95%。随后采用常规工艺可从浸出液中获得符合有关质量标准要求的V2O5和Al2O3产品。该工艺焙烧条件易控制,焙烧设备易解决,为石煤提钒的大规模商业化运行提供了一条新途径。     

高硅质石煤钒矿浸出机理研究

对高硅质石煤钒矿进行工艺矿物学分析和在硫酸体系下浸出机理的研究。结果表明,钒钛矿及含钒金红石、硫钒铜矿在硫酸直接浸出以及添加氟化物条件下,钒均难以浸出;钒酸盐、褐铁矿在硫酸体系下,钒易于浸出,氢离子破坏其晶体结构;含钒云母类矿物采用硫酸直接浸出,钒浸出率低于50%,在添加氟化物条件下,钒浸出率高于90%。氟化物强化含钒云母类矿物的浸出机理是HF与F-形成络合离子,在H_3O~+的促进下,破坏硅酸盐矿物晶体结构中的Si-O键,实现钒的浸出,HF在浸出过程起催化作用。     

Extraction of vanadium from athabasca tar sands fly ash

The production of refinery grade oil from the Alberta tar sands deposits as currently practiced by Suncor (formally Great Canadian Oil Sands Ltd.—GCOS) generates a substantial amount of petroleum coke fly ash which contains appreciable amounts of valuable metals such as vanadium, nickel and titanium. Although the recovery of vanadium from petroleum ash is a well established commercial practice, it is shown in the present work that such processes are not suitable for recovery of vanadium from the GCOS fly ash. The fact that the GCOS fly ash behaves so differently when compared to other petroleum fly ash is attributed to its high silicon and aluminum contents which tie up the metal values in a silica-alumina matrix. Results of experiments carried out in this investigation indicate that such matrices can be broken down by application of a sodium chloride/water roast of the carbon-free fly ash. Based on results from a series of preliminary studies, a detailed investigation was undertaken in order to define optimum conditions for a vanadium extraction process. The process developed involves a high temperature (875 to 950 °C) roasting of the fly ash in the presence of sodium chloride and water vapor carried out in a rotary screw kiln, followed by dilute sodium hydroxide atmosphereic leaching (98 °C) to solublize about 85 pet of the vanadium originally present in the fly ash. It was found that the salt roasting operation, besides enhancing vanadium recovery, also inhibits silicon dissolution during the subsequent leaching step. The salt roasting treatment is found to improve vanadium recovery significantly when the fly ash is fully oxidized. This is easily achieved by burning off the carbon present in the “as received” fly ash under excess air. The basic leaching used in the new process selectively dissolves vanadium from the roasted ash, leaving nickel and titanium untouched.     

Extraction of vanadium from V-Cr bearing reduced residue by selective oxidation combined with alkaline leaching

The extraction of vanadium from the V-Cr-bearing reduced residue formed from the waste water by reduction and neutralization in the process of extracting vanadium from vanadium slag was investigated by selective oxidation combined with alkaline leaching. Vanadium pentoxide is used as the selective oxidant. The effects of leaching temperature, leaching time, solution pH and vanadium pentoxide addition were studied. Under the most suitable conditions including a leaching temperature of 95°C, leaching time of 3?h, solution pH 13.0 and vanadium pentoxide addition of 4.55?wt-%, the leaching of vanadium reached 93.4% and the leaching of chromium was 17.1%.     

一步法制备碳氮化钒的工艺优化试验

围绕开发连续、高效、低成本的一步法合成碳氮化钒的技术,在总结氮化钒生产工艺过程研究的基础上,以V₂O₅为原料,焦炭为还原剂,经过破碎、混料和压制成块、烘干后进行还原氮化过程,在高纯氮气气氛下探索了高温碳热还原一步法制备碳氮化钒的最佳生产工艺条件。通过对V₂O₅的还原过程进行热力学分析计算并利用FactSage热力学软件对其进行理论研究,采用XRD、SEM等测试方法对反应温度、反应时间、氮气流量、制样压力等影响因素进行单因素试验分析,结果表明,碳化钒的氮化反应是逐级进行的,碳氮化钒的反应过程为V₂O₅→V₂O₄→V₂O₃→VC→VCN。试验中产生的CO会改变炉内气体分压,会对碳化温度和氮化温度产生影响,因此反应过程中应严格控制体系的CO和N₂分压;反应时间和氮气流量对反应产物的钒、氮、碳含量产生不同的影响,钒含量和氮含量随着反应时间的增加和氮气流量的...     

Leaching of vanadium from carbonaceous shale

The leaching of vanadium from carbonaceous shale using dilute H₂SO₄ was investigated, and the mechanism of leaching determined. The results showed that higher leaching efficiency of vanadium was obtained by increasing initial concentration of H₂SO₄, raising leaching temperature and prolonging leaching time. Addition of ammonium fluoride also enhanced recovery. A recovery of 92% was obtained using a liquid to solid ratio 4:1, initial H₂SO₄ concentration 18%, NH₄F addition 4.8 wt.% of carbonaceous shale, leaching temperature 95 °C and contact time 8 h; the recovery was only 56% without NH₄F. The presence of NH₄F enhanced the leaching of vanadiferous mica.     

溶剂萃取法从含钒浸出液中提钒的研究进展

提钒原料、浸出工艺及浸出条件等将决定浸出液中钒的存在形态及净化方法.溶剂萃取法可有效净化回收浸出液中的钒，具有处理量大、选择性高、可回收利用、产品纯度高等优点，在钒冶金中得到越来越广泛的应用.笔者针对不同提钒原料所得到的含钒浸出液，综述了各类萃取剂以一定萃取机制从中萃取钒的研究现状.讨论了萃取过程中溶液pH值、协萃剂、萃取时间、杂质元素及萃取预处理等因素对钒萃取分离的影响，并介绍了溶剂萃取法从含钒浸出液中提钒新技术，提出了钒溶剂萃取技术的未来发展方向.      

废弃SCR脱硝催化剂资源化利用研究进展

废弃SCR脱硝催化剂是一种危险废物,同时又含有多种有价成分。通过分析国内外废弃催化剂资源化利用的主要方法、原理、途径及优缺点,得到能够充分回收钒钨钛资源的有效方法主要为废弃SCR脱硝催化剂浸出-浸出液净化分离回收钒钨-浸出渣酸洗焙烧回收钛,其中浸出过程比较适合采用碱式焙烧-水浸法;浸出液净化分离过程比较适合采用化学沉淀法或溶剂萃取结合化学沉淀法。此外,展望了废弃SCR脱硝催化剂资源化利用的研究方向。     

Kinetics of vanadium dissolution from black shale in pressure acid leaching

The leaching kinetics of vanadium from black shale in the sulphuric acid-oxygen system is presented. The effects of agitation speed, leaching temperature in the range of 110-150 °C, sulphuric acid concentration, oxygen partial pressure and particle size on the rate of vanadium leaching were determined. The results indicate that the rate is nearly independent of agitation above 200 rpm and increases with increasing temperature, sulphuric acid concentration and oxygen partial pressure. As leaching occurs, there is a progressive dissolution of a vanadium-bearing alumino-silicate phase, while the inert quartz phase assembles onto the mineral surface and remains as an “ash” layer. The leaching kinetics was analyzed by using a new variant of the shrinking core model (SCM) in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. The determined activation energy was found to be 40.14 kJ/mol and the reaction orders with respect to sulphuric acid concentration and oxygen partial pressure were 0.61 and 1.67, respectively. A semi-empirical rate equation was derived to describe the process.     

Extraction of vanadium from black shale using pressure acid leaching

The extraction of vanadium from black shale was attempted using pressure acid leaching. The effects of the several parameters which included reaction time, concentration of sulfuric acid, leaching temperature, liquid to solid ratio and concentration of additive (FeSO₄) upon leaching efficiency of vanadium were investigated and a two-step counter-current leaching approach was developed. The results showed that the leaching efficiency of vanadium in the two-step process could reach above 90%. Vanadium was effectively separated and enriched by solvent extraction after leachate pretreatments, including the reduction of Fe³⁺ and adjustment of pH value. The extraction and stripping yields of vanadium were both > 98%. Ammonia was added to a stripping liquor to precipitate vanadium and then the ammonium poly-vanadate produced was calcined at 550 °C for 3 h to produce the high purity V₂O₅ powder. The overall yield of vanadium through all process stages was about 85%.     

熔融钒渣直接氧化提钒方法节能减排初步分析

为了分析熔融钒渣直接氧化提钒方法在节能减排方面的效果,计算对比了该方法与现行钒渣焙烧提钒工艺能耗,结果显示熔融钒渣直接氧化提钒方法比现行钒渣焙烧提钒工艺节能2.09×106kJ/t（钒渣）,相当于减排CO2 178.00kg/t（钒渣）。该方法可为钒渣提钒工业的节能减排作出巨大的贡献。     

粘土钒精矿中温直接浸出试验研究

研究和讨论了采用氟硅酸中温直接浸出粘土钒精矿的可行性,并对氟硅酸中温直接浸出的影响因素进行了研究,结合工艺矿物学探讨分析了氟硅酸浸钒机理。研究表明：氟硅酸可以很好破坏云母、粘土矿物、褐铁矿的结构,直接浸钒可行,浸出效率大于正常硫酸浸出。粘土钒精矿矿物结构的破坏与氟离子的浓度、温度相关。温度越高,粘土钒精矿分解反应越快。在中温浸出优化条件-200目≥85％,温度85℃,控制L／S为2．5～3：1、氟硅酸溶液（35％W／W）加入比2．0,浸出9h,钒浸出率可达96．58％,同时副产二氧化硅水合物。粘土钒精矿实现氟循环回收利用有望实现。