Knowledge Management System Of Institute of process engineering,CAS
|Thesis Advisor||张懿 ; 郑诗礼|
|Place of Conferral||北京|
|Keyword||钒酸钙 偏钒酸铵 碳化铵化 溶解度 冷却结晶|
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.
|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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