湿法磷酸萃取技术发展现状与研究进展

Development status and research progress of wet phosphoric acid extraction technology

  • 摘要: 磷酸作为一种重要的化工原料,在化工业中占有极其重要的地位. 磷酸的应用主要由磷酸的纯度决定,低纯度磷酸可用于工业和农业领域,而高纯度磷酸则可用于医药、食品和电子等行业. 我国磷矿以低品位磷矿为主,生产磷酸主要采用湿法工艺. 相比热法生产,湿法工艺更加清洁环保,但产品杂质含量多、种类复杂,故发展磷酸净化技术尤为重要. 本文从湿法磷酸纯化技术中的萃取法出发,综述了萃取法的主要研究进展. 重点介绍了溶剂萃取法、双水相萃取法、反胶团萃取法、超声协助萃取法和超临界流体萃取法的基本原理和发展趋势. 分析了不同萃取方法的优缺点、分离效果和适用条件. 突出介绍了溶剂萃取法,梳理了磷酸除杂的主要萃取剂,特别强调了复合萃取剂和新型萃取剂在磷酸纯化方面的显著优势,最后,对磷酸的萃取技术做出了前景展望.

     

    Abstract: Phosphoric acid, as a vital chemical raw material, holds an important position in the chemical industry. Its applications span across various sectors, determined largely by its purity. Low-purity phosphoric acid can be used in industrial and agricultural sectors, while high-purity phosphoric acid is essential for pharmaceuticals, food, electronics and other industries. The rising demand for batteries and semiconductors in recent years has led to increased requirements for phosphoric acid purity. There are two main methods for manufacturing phosphoric acid. The thermal method, while effective, is energy-intensive and environmentally unfriendly, conflicting with China’s green chemistry development goals. On the other hand, the phosphoric acid process, characterized by lower energy consumption, is more adept at handling China’s low-grade phosphate rock despite resulting in bulk and complex product impurities. Among various purification technologies, such as chemical precipitation, crystallization, electrodialysis, and ion exchange resin, the extraction method stands out. It offers environmental benefits, simple operation, and the capacity for large-scale production, marking it as a promising technique for phosphoric acid purification. This article summarizes in detail the research status of various extraction methods in recent years. It focuses on solvent extraction, aqueous two-phase extraction, reverse micelle extraction, ultrasonic-assisted extraction, and supercritical fluid extraction. It sorts out the solvent extraction method along with various extractants. The research on single extractants such as tri-n-butyl phosphate (TBP), methyl isobutyl ketone (MIBK), and n-octanol (NOA) has been primarily focused on identifying the optimal extraction conditions, including the O/A phase ratio, temperature, and air pressure. However, these single extractants typically target a single impurity, which limits their effectiveness in purifying phosphoric acid when multiple impurities are present. This limitation underscores the significant advantages of composite extractants in the purification process. Current research on composite extractants emphasizes determining the ideal proportion of extractants, often based on volume ratio, and establishing the optimal conditions for effective extraction. In addition to composite extractants, the development of new extractants offers promising solutions to the challenges posed by the low extraction efficiency of single extractants. Looking forward, the future of phosphoric acid extraction technology is poised for exciting developments: (1) The development of green composite extractants, alongside new extractants and materials combined with extractants, aims to achieve more efficient separation of impurities from phosphoric acid; (2) There is a growing interest in expanding research into the application of aqueous two-phase extraction and reverse micelle extraction for ion extraction, including the exploration of new aqueous phase systems; (3) The use of ultrasonic technology to accelerate the extraction process, coupled with studies on how supercritical fluids can improve the solubility and extraction efficiency of ions, represents another avenue for innovation. These advancements seek to reduce costs and explore specific application areas.

     

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