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钒酸钙碳化铵化制备钒产品应用基础研究
闫红
学位类型硕士
导师张懿 ; 郑诗礼
2016-07
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业化学工程
关键词钒酸钙 偏钒酸铵 碳化铵化 溶解度 冷却结晶
摘要

本文针对钒渣亚熔盐法钒铬共提清洁生产工艺中间产品钒酸钠的后续产品转化问题,重点开展了钒酸钙碳化铵化与偏钒酸铵结晶分离研究,可在获得合格钒产品的同时实现碱金属离子的再生循环。系统开展了钒酸钙碳化铵化反应规律、碳酸氢铵热分解规律、偏钒酸铵结晶热力学及结晶工艺的研究,在此基础上开发了钒酸钙低温碳化铵化-高温溶钒-钒酸铵冷却结晶工艺,并完成扩大试验,为万吨级钒渣亚熔盐法钒铬共提清洁生产示范工程的实施提供了坚实的理论和技术支撑。论文取得的创新性成果如下:(1)获得了各工艺参数对钒酸钙碳化铵化反应的影响规律。查明了CO2气体、反应温度、液固比、铵钒摩尔比、反应时间等因素对钒酸钙碳化铵化反应的影响,发现提高温度、增大液固比、为反应体系提供充足的碳源有利于提高钒转化率,并获得优化的反应条件,在此条件下钒转化率达97.35%。(2)测定了NH4+//VO3-,CO32-,HCO3--H2O体系溶解度相图,建立了偏钒酸铵冷却结晶分离方法。查明碳酸氢铵浓度、搅拌转速、降温速率、晶种添加量等条件对偏钒酸铵结晶的影响,发现较低碳酸氢铵浓度、适宜的搅拌转速、降温速率并适量添加晶种条件下有利于提高偏钒酸铵结晶率,获得偏钒酸铵冷却结晶优化参数,在此条件下最高结晶率可达84.2%。测定了偏钒酸铵结晶介稳区,通过加入碳酸氢铵进行盐析,可大幅度提高结晶率。(3)查明碳酸氢铵的热分解规律,发现在温度40℃-70℃,碳酸氢铵浓度10 g/L-100g/L的条件区间内,碳酸氢铵会分解产生氨气,影响操作环境。设计开发了钒酸钙低温铵化转化-高温溶钒-冷却结晶工艺路线,以控制铵分解。在35℃,液固比10:1,铵钒摩尔比3.0,反应后渣中钒含量可达1%以下。设计了两级反应-逆流浸出工艺,并进行初步循环实验,得到钒含量在1-2%之间的固相碳酸钙,浸出液结晶率达到68.2%。对碳化铵化全流程进行了扩大试验,工艺物料全部循环回用,最终得到纯度达98.5%的五氧化二钒产品,全过程无废水排放,表明工艺设计合理可行。

其他摘要

Based on the subsequent transformation of sodium vanadate which was produced during the vanadium-chromium co-extraction by vanadium slag sub-molten salt roasting process, the calcium vanadate carbonization-ammonium reaction, thermal decomposition of ammonium bicarboncate, ammonium metavanadate crystallization thermodynamics and crystallization process were investigated in this paper with calcium vanadate carbonization-ammonium process and the following ammonium metavanadate crystallization separation process as a core. Based on the study of calcium vanadate carbonization-ammonium reaction rules, the optimum condition was obtained. The efficient crystallization separation method was established by measuring the phase solubility diagram of NH4+//VO3-,CO32-,HCO3--H2O system. On this basis, the research on cooling crystallization process, metastable region and salting-out crystallization were carried out. In consideration of ammonia emission when industrial operation is conducted, the calcium vanadate low temperature carbonization-ammonium reaction-high temperature vanadium leaching-ammonium metavanadate cooling crystallization process was developed. This process improves the sodium vanadate multistage cation substitution process, realizes the non-pollution of the whole process, thus providing the theoretical support for the ten thousand tons demonstration project of vanadium-chromium co-extraction by vanadium slag sub-molten salt roasting process. Innovative achievements in this paper including:1. The reaction rules of calcium vanadate carbonization-ammonium were obtained. The effects of CO2, NH4+-V mole ratio, liquid-solid ratio and reaction time were investigated and the optimal process conditions were obtained, which made the vanadium conversion from calcium vanadate reached 97.35%.2. The optimal conditions of ammonium metavanadate crystallization process were obtained. The cooling crystallization process was determined by measuring the phase solubility diagram of NH4+//VO3-,CO32-,HCO3--H2Osystem. The effects of ammonium bicarboncate concentration, stirring speed, cooling rate and seed crystal addition were investigated and the optimal process conditions were obtained which made the crystallization ratio reached 84.2%. The metastable region of NH4+//VO3-,CO32-,HCO3--H2Osystem was measured the same time in order to optimize the crystallization process.3. The thermal decomposition of ammonium bicarboncate was investigated, and in order to control the decomposition of ammonium bicarboncate, the calcium vanadate low temperature carbonization-ammonium reaction-high temperature vanadium leaching-ammonium metavanadate cooling crystallization process was developed. Through the study on low temperature carbonization-ammonium reaction, the optimal conditions of calcium vanadate low temperature(35℃) reaction were obtained with vanadium content in calcium carbonate slag less than 1%. The two-stage reaction process was developed based on this low temperature carbonization-ammonium reaction and the preliminary cycle experiment was conducted, obtaining calcium carbonate slag with vanadium content between 1-2%. The ammonium metavanadate crystallized from the follow-up lixivium obtained and the crystallization ratio reached 68.2%. The calcium vanadate low temperature carbonization-ammonium reaction-high temperature vanadium leaching-ammonium metavanadate cooling crystallization process realizes the cycling of reaction medium and there is on waste water discharged the whole process. 

语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/22933
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闫红. 钒酸钙碳化铵化制备钒产品应用基础研究[D]. 北京. 中国科学院研究生院,2016.
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