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Alternative TitleStudy on Molten Salt Reaction and Purification of Titanyl Sulfate Solution in Treatment of Titania-rich Slag using Molten Salt Method
Thesis Advisor齐涛
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword富钛料 二氧化钛 混合熔盐 动力学 脱硅
Abstract富钛料(TiO2含量为70%~85%)是工业生产钛白的重要原料,主要采用电炉熔炼法生产;既可以直接用作硫酸法原料,也可经提质后用于氯化法。硫酸法存在废弃物量大、环境污染重等问题,氯化法对原料品位要求高,产生高毒的氯化物需深井填埋处理;基于此,团队提出并研发成功了NaOH熔盐法钛白清洁生产新技术,并在山东东佳集团完成千吨级中试,通过工艺鉴定。新技术采用高钛渣(TiO2含量90%~92%)为原料,经济效益和市场竞争力低,为此,本论文采用更低品位富钛料(TiO2含量78%)代替高钛渣进行熔盐法生产钛白的应用基础研究。 本论文针对采用富钛料为原料带来的一系列问题,开展了系统应用基础研究,优化了工艺过程,并水解出粒度合格的偏钛酸,进一步完善熔盐法钛白清洁生产技术体系。取得的主要创新性成果如下: (1) 解决了富钛料熔盐反应结块难题。深入分析了富钛料为原料进行熔盐反应结块原因,提出了采用加入添加剂法和两步升温法解决结块难题,并分析了其防止结块的原因。 (2) 系统研究了NaOH-KOH混合熔盐分解富钛料过程。富钛料NaOH-KOH混合熔盐分解过程宏观动力学研究表明,该浸出过程符合未反应收缩核模型,反应浸出速率受内扩散控制,反应活化能为43.1kJ/mol;在反应温度为350℃、反应时间为45min的优化工艺条件下,钛浸出率可达到98.1%;采用分子模拟的手段分析了黑钛石在NaOH-KOH混合熔盐体系生成NaKTiO3的反应历程;获得了NaOH-KOH混合熔盐与富钛料熔盐产物的水洗优化工艺条件,在该条件下,Na+和K+的回收率分别可以达到86%和98%。 (3) 深入研究了NaOH-NaNO3混合熔盐分解富钛料的过程。富钛料NaOH-NaNO3混合熔盐分解过程宏观动力学研究表明,该过程符合未反应收缩核模型,反应浸出速率受化学反应控制,反应活化能为62.6kJ/mol;最佳工艺条件下,钛浸出率达到98%,最佳反应温度为400℃;同时对NaOH-NaNO3混合熔盐分解富钛料的反应历程进行推理。 (4) 解决钛液深度脱硅难题。研究并获得钛液深度脱硅优化工艺条件如下:采用质量浓度为0.5%的阳离子聚丙烯酰胺絮凝剂,体积加入量8%,絮凝时间4h,在该条件下,钛液中的硅含量降至30ppm以下,并分析了絮凝脱硅机理;脱硅后钛液经水解可制备得到粒径分布合格的偏钛酸。
Other AbstractTitania-rich slag with the content of 70 wt% to 85 wt% is an important raw material in the production of pigment titanium dioxide. Titania-rich slag maily comes from the reduction of ilmenite in electric furnace. It can be directly used as the raw meterials of sulfate process. After remove the impurities, it can also be used as the raw meterials of chloride process. In the sulfate process, a large amount of wastes by-products, such as spent sulfate acid and copperas, are produced, resulting in serious environmental problems. In the chloride process, less wastes was produced. On the other hand, high grade titanium slag was needed (high titanium slag or rutile) and high toxicity chloride was produced which needs deep landfill. Furthermore, the technology has been monopolized by the foreign companies such as DuPont. Recently, a novel metallurgical process for TiO2 production has been developed by the Institute of Process Engineering, Chinese Academy of Sciences. A demonstration plant has been built in Shandong Province, which has approached zero emission of pollution. In this process, high titanium slag (content of TiO2 is 91.8 wt.%) was used as raw materials. As the price of the raw material (high titanium slag) is relatively expensive, the economy of this new process has no advantages over the existing process. In order to elevate the market competitiveness of this new process, relatively low grade titanium slag — titania-rich slag (78 wt%) has been used in this thesis. This thesis focus on solving the problems by using titania-rich slag as raw material and the corresponding application and fundamental research has been done. The feasibility of the process by using the titania-rich slag as raw material has greatly elevated. Meanwhile, the process was optimized, the energy consumption was reduced, the impact of the impurities on the process was reduced and qualified products were obtained. The thesis laid the fundamental by using low grade titanium slag in the future. In this thesis, the following results and progresses were achieved: (1) The reason of caking in the process of molten salt reaction has been analyzed. Two feasible approach has been given to solve the problem: adding addictive and two-step reaction and reason of anti-caking was analyzed. (2) The process of eutectic NaOH-KOH binary molten salt reaction was studied. A kinetic study of the decomposition of titania-rich slag in the temperature range from 250℃ to 350℃has also been investigated. The kinetics investigation indicates that the decomposition of titanium slag is controlled by mass diffusion in residual layer and the apparent activation energy is 43.1 kJ/mol. Under conditions of temperature 350℃ and mixed alkali-to-titanium slag ratio 1.4:1, titanium conversion ratio obtained is >98% with reaction time around 45min. The mechanism of titanium slag decomposed in monten NaOH-KOH has been analyzed by using software.The water leaching process of the intermediate product of the eutectic NaOH-KOH binary molten salt reaction has been studied. Under the optimized conditions, 98% of KOH and 86% of NaOH can be recycled by three-stage counter-current leaching process. (3) The process of NaOH-NaNO3 binary molten salt reaction was studied. The kinetics investigation indicates that the decomposition of titanium slag is chemical reaction controlled process and the apparent activation energy is 62.6 kJ/mol. Under the optimized conditions, 98% of titanium can be decomposed and the optimal reaction temperature is 400℃. The mechanism of titanium slag decomposed in monten NaOH-NaNO3 has been studied. (4) Flocculation of silica gel from titanyl sulfate solution by cationic polyacrylamide CCE-801 was studied. The mechanism of desilicication has been analyzed. Under the optimized conditions, the content of SiO2 can by reduced to 30ppm by adding 8% flocculant solution. The concentration of flocculant solution is 0.5wt%, and flocculation time is 4h.
Document Type学位论文
Recommended Citation
GB/T 7714
王东. 富钛料为原料熔盐法工艺中熔盐反应和钛液净化研究[D]. 中国科学院研究生院,2014.
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