湿法磷酸深度脱氟精制食品级磷酸工艺研究

发布时间：2018-06-02 04:34

本文选题：湿法磷酸 + 萃取磷酸　；参考：《昆明理工大学》2015年硕士论文

【摘要】：磷酸作为磷化工生产过程中最为关键的中间体,是生产磷酸盐、磷肥等的主要原料之一。随着磷化工精细化的发展,各种级别的磷酸市场需求不断加大,而近年来我国磷化工一直存在产能严重过剩、产品质量低、结构单一,精细化程度不够,国际市场竞争力不强的缺陷。为了实现磷化工行业的可持续发展,湿法磷酸净化技术已成为研究的热点。云天化国际三环分公司所生产湿法磷酸同样存在杂质多、P205含量较低的问题。目前三环分公司已与四川大学合作,通过预处理、溶剂萃取(磷酸三丁酯)、洗涤及反萃进行净化精制,精制生产的磷酸除氟外,其他指标均能达到食品级质量标准,本文针对该现状,以三环公司现有的湿法磷酸净化后的萃取磷酸为原料,拟开展湿法磷酸深度脱氟研究,欲使其达到食品级磷酸质量标准,即氟含量降到10mg/L (10ppm)以下。本文以脱氟率及P205收率为主要指标,应用单因素实验与正交实验相结合的方法,分别探索了稀碱液洗涤、真空浓缩、氮气汽提三种方法的脱氟效果。首先采用稀碱液洗涤萃取酸的有机相进行脱氟,单因素实验得到的较优化条件为：稀碱液浓度20%；稀碱液用量1.4%；稀碱液洗涤温度45℃。随后进行正交实验,得出较优化的操作条件为稀碱液浓度20%,用量1.4%,洗涤温度45℃,此时脱氟率达67.75%,有机相中P205收率达95.50%,经蒸馏水反萃后磷酸中氟含量降至272ppm。说明单一的稀碱液洗涤磷酸脱氟效果还达不到食品级磷酸标准。然后对精制磷酸进行真空浓缩脱氟实验研究。单因素实验得出的较优化条件为：浓缩时间120min：脱氟剂添加量是磷酸中氟含量理论量的200%：浓缩温度85℃。随后进行正交实验,实验结果为浓缩时间120min,硅藻土用量是理论量的200%,浓缩温度为90℃时,脱氟率达到66.72%,氟含量降到160ppm左右,浓缩酸磷质量浓度w(P205)达67.53%。说明真空浓缩脱氟效果也未达到食品级磷酸标准。再者采用氮气汽提脱氟实验研究,结果表明较优化的工艺条件为：汽提时间120min、硅藻土添加量是磷酸中氟含量理论量的200%、汽提温度900C、氮气通气量0.5-0.6L/min、搅拌速度300r/min。在较优条件下,脱氟率可达85%以上,氟含量降到110ppm左右,浓缩酸磷质量浓度w(P205)达70%左右。说明氮气汽提脱氟效果仍未达到食品级磷酸标准。由以上三种单一方法脱氟,均未达到食品级磷酸标准,是由于原料酸含有多种杂质如铁、铝、镁、硫酸根等离子,影响了氟在磷酸中的存在形式,使其存在形式多样化,从而难以实现预计的脱氟目标。鉴于此,最后设计将上述三种方法串联集成,初步实验结果显示氟含量可降至10ppm左右,汽提后磷酸中磷质量浓度达到72%左右。该集成技术能有效脱除萃取磷酸中的氟,为湿法磷酸深度脱氟精制食品级磷酸提供了新的思路。本研究不仅有利于拓宽云天化生产工业磷酸的利用途径,提高企业自身的经济效益和市场竞争力,充分实现资源的有效利用,还可以为磷化工产品的精细化、专业化发展提供一定的技术支撑。
[Abstract]:Phosphoric acid is one of the most important intermediates in the process of phosphorous chemical production. It is one of the main raw materials for the production of phosphate and phosphate. With the development of fine phosphorus chemical industry, the demand of various levels of phosphoric acid is increasing. In recent years, there has been a lot of heavy production capacity, low product quality, single structure and insufficient fine degree in the phosphorus chemical industry in recent years. In order to realize the sustainable development of the phosphorous and chemical industry, the wet process phosphoric acid purification technology has become the hot spot of research. The wet process phosphoric acid produced by the international tricyclic company of Yunnan Tianhua has the same impurity and low P205 content. At present, the three ring branch company has been working with the Sichuan University by preprocessing and dissolving. The other indexes can reach the food grade quality standard. In this paper, the research on deep defluorination of wet process phosphoric acid is intended to be carried out to reach food grade phosphorus. The standard of acid quality, that is, the content of fluorine drops below 10mg/L (10ppm). In this paper, the defluorination effect of three methods, dilute alkaline solution, vacuum concentration and nitrogen stripping, is explored by the combination of single factor experiment and orthogonal experiment with the defluorination rate and the yield of P205 as the main index. The optimum conditions of fluorine were as follows: the concentration of dilute alkali solution was 20%, the dosage of dilute alkaline solution was 1.4%, the washing temperature of dilute alkaline solution was 45. Then orthogonal experiment was carried out. The optimum operating conditions were 20%, 1.4% and 45, the defluorination rate was 67.75%, the P205 yield of the organic phase was 95.50%, and the distilled water was reversed. The content of fluorine in the extracted phosphoric acid decreased to 272ppm., indicating that the defluorination effect of a single dilute lye washing phosphoric acid could not reach the standard of food grade phosphoric acid. Then, the experimental study on the defluorination of refined phosphoric acid was carried out in vacuum concentration. The optimum conditions of the single factor experiment were as follows: concentration time was 120min: the addition of defluorinated agent was 200% of the theoretical amount of fluorine content in phosphoric acid. The concentration temperature was 85. Then the experiment was carried out. The result was the concentration time 120min, the dosage of diatomite was 200% of the theoretical amount, the defluorination rate reached 66.72%, the fluorine content was about 66.72%, the fluorine content was reduced to about 160ppm, the concentration of concentrated acid phosphorus was w (P205) to 67.53%., indicating that the effect of true air concentration and defluorination did not reach the standard of food grade phosphoric acid. The experimental study of nitrogen stripping defluorination shows that the optimum technological conditions are as follows: the extraction time is 120min, the addition of diatomite is 200% of the theoretical amount of fluorine content in phosphoric acid, the stripping temperature is 900C, the nitrogen ventilation is 0.5-0.6L/min, and the rate of defluorination can reach more than 85%, and the content of fluorine drops to about 110ppm under the favorable conditions. The concentration of W (P205) is about 70%. It shows that the defluorination effect of nitrogen stripping has not reached the standard of food grade phosphoric acid. Defluorination by the above three single methods has not reached the standard of food grade phosphoric acid. It is because the raw acid contains a variety of impurities such as iron, aluminum, magnesium and sulfate, which affect the existence form of fluorine in phosphoric acid and make it form. It is difficult to achieve the expected defluorination target. In view of this, the three methods are integrated in series. The preliminary experimental results show that the fluorine content can be reduced to about 10ppm and the phosphorus concentration in the phosphoric acid is about 72% after stripping. The integrated technology can effectively remove fluorine in the extraction of phosphoric acid and refine the defluorination of the wet process phosphoric acid. Food grade phosphoric acid provides a new way of thinking. This study not only helps to widen the utilization of phosphoric acid in the industrial production, improve the economic and market competitiveness of enterprises, fully realize the effective utilization of resources, but also provide some technical support for the refined and specialized development of phosphorus chemical products.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ126.35

【参考文献】