Knowledge Management System Of Institute of process engineering,CAS
中国科学院过程工程研究所发现了亚熔盐介质中高反应活性氧负离子（HO2-、O2-、O22-等）对矿物中低价态金属原子具有显著的催化氧化作用，可大幅强化介质氧化分解矿物能力，亚熔盐介质氧化活性调控的核心即是实现介质中各种活性氧的量化调控。为进一步优化钒渣亚熔盐法的钒铬共提工艺，基于微气泡可爆裂强化碱介质中活性氧的生成、提高介质中氧气溶解度这一典型的物理化学特征，本文提出了微气泡强化亚熔盐介质液相氧化法分解钒渣新技术，在对介质中活性氧进行量化测定的基础上，对新技术在全球典型高品位钒渣、含铬钒渣高效提钒及钒铬共提应用上的可行性、机理、工艺参数确定、动力学等进行了系统研究，为钒渣亚熔盐法高效提钒、钒铬共提清洁生产工艺提供了坚实的理论支撑和应用指导。论文取得如下创新性成果：1. 建立了采用三价铬氧化法来定量检测高温高碱亚熔盐介质中活性氧含量的新方法，系统测定了不同温度、碱浓度区间亚熔盐介质中活性氧含量。测定结果表明，活性氧的生成量受介质的热力学和动力学调控，热力学上取决于OH-的浓度和氧气溶解度，动力学上取决于介质的传质和流动性能。随着反应温度的上升，亚熔盐介质的粘度降低，介质的传质和流动性能得到改善，活性氧生成量增加；随着碱浓度的上升，热力学上会提供更多的OH-离子，但是同时会降低氧气溶解度，动力学上降低了介质的传质性能，因此活性氧的生成浓度随碱浓度呈现先升高后降低的趋势。2. 实验证实了微气泡可极大强化钒铁尖晶石矿物在亚熔盐介质中的氧化分解。以全球最为典型的高品位芬兰钒渣为研究对象，采用微气泡强化在碱浓度40%、反应温度110 oC即可实现钒的高效浸出。动力学研究表明，在无强化条件下，钒的浸出速率受界面化学反应控制，表观反应活化能为28.88 kJ/mol，而采用微气泡强化亚熔盐技术钒的浸出速率受内扩散控制，表观反应活化能为20.17 kJ/mol，这说明微气泡强化促进了介质中活性氧的生成，从而在热力学上促进了钒渣中钒的浸出，降低钒渣中的钒的浸出活化能。3. 获得了钒渣含铬量对微气泡强化亚熔盐介质氧化分解钒渣提钒的影响机理及规律。以典型的含铬钒渣承钢钒渣和德胜钒渣为研究对象进行微气泡强化反应，结果表明钒渣中铬含量越高，钒的浸出难度越大，在碱浓度60%、反应温度140 oC方可实现含铬钒渣中钒的高效浸出。动力学研究表明，在微气泡强化亚熔盐工艺中，铬的浸出受化学反应控制，钒的浸出受内扩散控制，含铬量的提高会增加钒渣中钒的浸出难度，提高钒的浸出表观活化能。4. 微气泡强化亚熔盐技术的实验研究表明，钒铬浸出的最优条件也是活性氧生成的最佳区间，间接证明亚熔盐介质中的活性氧是其高效分解两性金属矿物的关键。微气泡强化亚熔盐技术经千吨级扩试、五万吨级产业化应用，均能在温和条件实现钒渣中钒铬共提，并首次在工业规模实现了≤150 oC钒渣中的钒铬共提, 展现出了良好的工业应用前景。;Reactive oxygen species (ROS, HO2-, O2-, O22-, etc.) in the sub-molten salt medium are highly reactive and can effective promote the decomposition and oxidization amphoteric metal oxide ores. The reactivity of the sub-molten salt medium is dependent on the amount of the reactive oxygen species generated in the medium. Because fine bubble can efficiently improve the oxygen solubility and promote the formation of ROS in the medium, we have studied the fine bubble intensified oxidation technology to optimize the sub-molten salt technology for the co-extraction of vanadium and chromium vanadium slag, and developed a new method to treat vanadium slag. By manipulation the generation of ROS in the medium, highly efficient recovery of vanadium from high-grade vanadium slag and co-extraction of vanadium and chromium from chromium-containing vanadium slag have been realized. The feasibility, mechanism, process parameters and kinetics of leaching process were systematically studied, providing theoretical support and application guidance for the design of new process and achieving efficiently extract vanadium and chromium from the vanadium slag using sub-molten technology.The thesis achieved the following innovative results:1. A new method for quantitative determination of ROS in high temperature and high alkali concentration sub-molten salt medium was established based on the oxidation of Cr(III). The effect of temperature and alkali concentration on the generation of ROS in the sub-molten salt medium was systematically investigated. The results showed that the amount of ROS in the media was in general governed by the reaction thermodynamics including the OH- concentration, temperature and the oxygen solubility and kinetics including the mass transfer and viscosities of the medium. As the reaction temperature increased, the viscosity of the sub-molten salt medium decreased, improving the mass transfer and consequently the increase of ROS. As the alkali concentration increased, more OH- ions were provided, favoring the generation of ROS thermodynamically; however, solubility of oxygen and the mass transfer coefficient of the medium was reduced significantly, in favor of the ROS generation. The balance of the two controversial effects resulted in the observed initial increase and subsequent decrease of the ROS when alkali concentration increased.2. Experiments have confirmed that fine bubbles could significantly enhance the oxidative decomposition of vanadium iron spinel minerals in sub-molten medium. Using the typical Finnish vanadium slag as an example, highly efficiency leaching of vanadium could be achieved at 110 oC in 40% NaOH solution due to the fine bubble intensification effect. The kinetic study showed that without the fine bubble intensification, the leaching rate of vanadium was controlled by the interface chemical reaction and the activation energy of apparent reaction was 28.88 kJ/mol. In contrast, with the fine bubble intensification, the leaching rate of vanadium was controlled by internal diffusion and the activation energy of the apparent reaction was 20.17 kJ/mol. These results suggested that the fine bubble could promote the generation of ROS in the medium, decrease the reaction activation energy and promote the oxidation of vanadium slag.3.The effect of chromium on vanadium leaching was studied using fine bubble intensified sub-molten salt technology, and the chromium-containing vanadium slag from Chengde Steel and Desheng Steel was investigated. The leaching results showed that the chromium content in vanadium slag had significant effects on the vanadium leaching. Compared with the Finnish vanadium slag, the leaching of vanadium was much more difficult due to the presence of chromium spinel in the slag, and the alkali concentration was 20% higher and the temperature was 20 oC higher in order to leach out the vanadium effectively. The kinetic study showed that the leaching of vanadium was controlled by internal diffusion and the leaching of chromium was controlled by chemical reaction. Further, the increase of chromium content was unfavorable for the leaching of vanadium as evidenced by the increase of the vanadium leaching apparent activation energy as the chromium content increased.4. Experimental results showed that the optimal conditions for vanadium and chromium leaching were also the optimal conditions for the ROS generation, indirectly proving that the ROS in the sub-molten salt medium was critical for the efficient decomposition and oxidation of minerals. The fine bubble intensified sub-molten salt technology could achieve co-extraction of vanadium and chromium under mild reaction conditions, and the technology has been examined in 1,000 ton/a piolet plant test and 50,000 ton/a industrial scale production line. Synergistic extraction of vanadium and chromium from chromium-containing vanadium slag at 150 °C was realized for the first time on industrial production line, suggesting the new technology has great potential and prospects for large scale industrial application.
|刘龙杰. 微气泡强化亚熔盐液相氧化法基础及应用研究[D]. 中国科学院大学,2018.|
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