【作者】 徐耀兵；

【导师】 王勤辉； 骆仲泱； 倪明江；

【作者基本信息】 浙江大学 ， 热能工程， 2009， 博士

【摘要】 钒具有优异的物理化学性质,在国防、冶金、化工和医学等行业有着广泛的应用,目前,国际、国内钒冶金行业发展迅速。国外提钒工业受提钒原料及提钒工艺所限,钒产量提高能力有限。国内市场主要依靠钒钛磁铁矿生产钒产品,钒产能受到钢铁产品产能的限制。石煤是我国另外一种重要的含钒矿物,但开发利用难度较大。为满足国际国内市场对钒产品日益增长的需求,必须加大对石煤钒矿资源的开发利用。石煤提钒技术工艺较多,但大多数都存在着污染严重、回收率低。资源浪费严重等问题。在对现有的石煤提钒工艺进行对比分析后,提出中间盐法石煤灰渣酸浸提钒工艺,具体为：石煤灰渣硫酸浸取→酸浸液提取铵明矾→结晶中间盐→中间盐溶解→萃取→反萃取→氨法沉钒→热解脱氨→V2O5产品。石煤灰渣浸取阶段使用硫酸作为浸出剂,合理的酸浸工艺条件为：硫酸浓度6mol/L、酸浸温度115℃、浸取时间4h、液固比3:1条件下,V2O5酸浸效率达到85.52%。对浸出过程动力学分析表明,灰渣中V2O5浸出过程处于固膜扩散控制过程,酸浸温度对提高V2O5酸浸效率有显著的作用。本工艺中提出用强酸溶液中结晶铵明矾的技术方法来除去溶液中绝大部分的Al3+离子。合理的铵明矾结晶工艺条件为：在硫酸铝浓度150-200 g/L,铵/铝摩尔比1.2左右,冷却速度15℃/h左右,结晶温度5℃左右条件下,铵明矾结晶率达到89.52%,酸浸液中的Al2O3浓度下降至5g/L左右。本文中提出中间盐结晶技术方法,从强酸溶液中提取V2O5。溶液温度140℃、酸度9mol/L、添加剂C、添加剂比例系数0.3等条件下,V2O5结晶率达到96.72%,溶液中V2O5浓度为0.37g/L。将滤液(返酸)返回酸浸阶段循环使用,可以节约51%的新酸投入。。中间盐晶体中V2O5含量4-6%,是灰渣含钒量的3-5倍。中间盐是一种水溶性较强的晶体,在温度95℃、液固比2：1、溶解时间4h的条件下,中间盐溶解效率达到99.63%。中间盐溶解液经还原、中和后,进行萃取,反萃取,反萃液氨法沉钒,多钒酸铵热解得到V2O5,V2O5产品纯度99.34%。中间盐法石煤灰渣湿法提钒工艺小试试验取得了圆满成功,全流程V2O5总回收率为82.80%。为验证小试试验所得工艺参数的合理性,检验提钒工艺的适用性,在小试试验获得成功后,我们对本工艺进行了放大规模的中试实验研究。中试实验规模为日处理灰渣700Kg,中试实验采用小试试验所得工艺参数,中试实验共分为三个阶段：新酸浸取实验、返酸浸取实验、中间盐溶解至热解脱氨实验,单个阶段依次进行,每个阶段连续运行48小时以上,中试实验共获得V205产品2530.7g。中试实验取得了与小试试验相同水平的技术指标,全流程V205总回收率为81.46%。中试实验结果说明,小试试验所得工艺参数是正确、合适的,同时证明了中间盐法石煤灰渣湿法提钒工艺在放大规模实验中的适用性,为日后的大规模工业生产提供了可靠的参考依据。本文用化学分析、SEM-EDS扫描电镜分析、XPS电子能谱分析、XRD衍射分析等分析手段,对中间盐晶体成分及物相组成进行分析,综合各项分析结果可知,中间盐中的物相组成为：K1.11V3O8、(NH4)(FexV1-x)(SO4)2、(NH4)Al(SO4)2、(NH4)Al(SO4)212H2O等四种。定量分析结果表明,中间盐晶体中K1.11V308含量仅为1.23%。因此,将中间盐晶体定位为一种多金属复合铵盐,其成分表达式可以表示为：(NH4)(AlxFeyVz)(SO4)2·nH2O,其中x+y+z=1,n=0或12。提出了中间盐晶体中含钒物相的生成反应方程式,依据经验公式,对含钒物相的热力学参数进行了估算,对两种含钒物相的生成反应进行了热力学计算,从理论角度对含钒物相的生成反应进行了分析,确定了K1.11V308的生成步骤。更多还原

【Abstract】 Vanadium has got the extensive application in national defense, metallurgy, chemical and medicine, which leads to the rapid progress of vanadium products price and rapid development of vanadium metallurgy. However, the overseas vanadium throughout is restricted by the resource and technology, the output of vanadium products cannot get greatly raised. As for home market, the output is restricted by the output of iron product. Stone coal is another important mineral resource of vanadium in china..But it is difficult to get full use of the low grade stone coal. In order to fulfill the market demand of vanadium products, it is necessary to develop new technique to extract vanadium from stone coal.There have been so many process for vanadium extraction from stone coal. Due to environment pollution, low recovery rate and serious waste of the resource, clean and efficient process seldom appeared. Comparing and analyzing these existed vanadium extraction process, we propose a new process to extract vanadium from low grade stone coal:vanadium extraction by interim product with sulfuric acid leaching from ash of stone coal. It contains:acid leaching by sulfuric acid, aluminum ammonium sulfate crystallizing from leachate, interim product crystallizing, interim product dissolved by water, solvent extraction, back extraction, vanadium precipitation by ammonia and pyrogenation to be vanadium pentoxide.In the leaching phase, high concentration sulfuric acid is used to be leaching solution. The optimal operation conditions are as followed:the concentration of sulfuric acid is 6 mol/L, the leaching temperature is 115℃, the leaching time is 4 hours and the ratio of L/S is 3:1. With these conditions, leaching efficiency is 85.52%. The leaching kinetics of vanadium pentoxide is approached. The result shows that the diffusion through the solid film is the main limited step. Vanadium leaching efficiency is affected by temperature greatly. Aluminum ammonium sulfate crystallization method is proposed to remove the voluminous Al3+ in leachate. The optimal operation conditions are as followed:the concentration of aluminum sulfate is between 150 and 200 g/L, the molar ratio of ammonium to aluminum is about 1.2, cooling rate is about 15℃/h and the crystallization temperature is about 5℃。With the optimal operation conditions, the crystallization efficiency of aluminum ammonium sulfate is 89.52%, the concentration of aluminum sulfate in leachate is just about 5 g/L.In this research, interim product crystallizing method is proposed to extract vanadium from high concentration sulfuric acid. The optimal operation conditions are as followed:crystallizing temperature is 140℃, sulfuric acid concentration is over 9 mol/L, addictive is C, and the coefficient is 0.3. With the optimal operation conditions, interim product crystallization efficiency is 96.72%. The concentration of vanadium pentoxide in the filtrate is just 0.37g/L. The filtrate is named back acid and it goes back to the leaching phase. The dosage of sulfuric acid can be reduced by 49%. The content of vanadium pentoxide in interim product contains is between 4% and 6%, as 3to 5 times of ash.Interim product crystal can be dissolved by water easily. The optimal operation conditions are as followed:temperature is 95℃, L/S is 3:1, dissolving time is 4 hours. With the optimal operation conditions, the dissolution efficiency is 99.63%. The solution of dissolving interim product is deoxidized and neutralized. After that, the solution is extracted by organic solvent. The next phase is back-extraction, oxidization, precipitation and pyrogenation. The purity of vanadium penoxide is 99.34%.The interim product process of vanadium extraction succeeds in lab scale experiment study. Totally recovery rate of vanadium is 82.80%. To check the rationality of operation conditions conclude from lab experiment and applicability of the process, pilot-scale experiment is presecuted after the lab scale experiment.700kg ash was leached in the pilot-scale experiment, operation conditions of pilot-scale experiment is the same as lab scale experiment. Pilot-scale experiment is divided into three phases:sulfuric acid leaching experiment, back-acid leaching experiment and from interim dissolution to pyrogenation experiment. Each phase lasts over 48 hours.2530.7g vanadium penoxide is the main product of Pilot-scale experiment. Technical achievement is comparative to the lab scale experiment. Totally recovery rate of vanadium penoxide is 81.46%. Results of pilot-scale experiment show that operation conditions of lab scale experiment are feasible for large scale experiment. It provide dependable reference to the industry manufacture.In this research, interim product is researched by chemical analyze, SEM-EDS analyze, XPS analyze, XRD analyze and etc. for its chemical composition and phase composition. Result of all kinds of analyze show that the phase composition of interim product are K1.11V3O8, (NH4)(FexV1-x)(SO4)2, (NH4)Al(SO4)2, (NH4)Al(SO4)212H2O. Quantification analyzes shows that the content of K1.11V3O8 in the interim product is just 1.23%. So, interim product is named by complicated ammonium salt of kinds of metal. Structural formula of it is (NH4)(AlxFeyVz)(SO4)2·nH2O, which the sum of x, y, z is land n is Oor 12. With the predigestion and hypothesis of chemical reaction of interim product, Chemical equation of interim product was proposed based on the result of all kinds of analyze. By means of empirical equation, thermodynamic parameters of interim product are estimated. Chemical reaction of K1.11V3O8, (NH4)(FexV1-x)(SO4)2 are calculated in the light of thermodynamic function of state Gibbs Free Energy.更多还原