SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (7): 1824-1831.DOI: 10.1016/j.cjche.2020.01.005

• Catalysis, Kinetics and Reaction Engineering • Previous Articles     Next Articles

The fouling properties of SiO2-CaO-P2O5 system in high-temperature rotary kiln phosphoric acid process

Pan Wu1, Li Lü1, Siyang Tang1, Changjun Liu1,2, Hairong Yue1,2, Wei Jiang1, Bin Liang1,2   

  1. 1 Low-carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China;
    2 Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China
  • Received:2019-02-18 Revised:2019-11-15 Online:2020-08-31 Published:2020-07-28
  • Contact: Bin Liang
  • Supported by:
    The authors are grateful for the support from the National Key R&D Program of China (2018YFC1900201), the Provincial Key R&D Program of Shanxi (201603D31212003).

The fouling properties of SiO2-CaO-P2O5 system in high-temperature rotary kiln phosphoric acid process

Pan Wu1, Li Lü1, Siyang Tang1, Changjun Liu1,2, Hairong Yue1,2, Wei Jiang1, Bin Liang1,2   

  1. 1 Low-carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China;
    2 Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China
  • 通讯作者: Bin Liang
  • 基金资助:
    The authors are grateful for the support from the National Key R&D Program of China (2018YFC1900201), the Provincial Key R&D Program of Shanxi (201603D31212003).

Abstract: Kiln phosphoric acid (KPA) technology could produce P2O5 with high purity and has been applied in thermal phosphoric acid industry; however the formation of fouling in the high-temperature rotary kiln restricts the stable and long-term operation. In this paper, the reaction of phosphate ores with gaseous P2O5 was investigated in a high-temperature reactor, and the CaO-SiO2-P2O5 ternary phase diagram was analyzed to understand the fouling formation mechanism. The results showed that the low-melting-point products, such as Ca(PO3)2 and Ca2P2O7, are responsible for the fouling in the KPA process. In addition, a small amount of impurities, e.g., aluminum and iron, could facilitate the generation of the low-melting-point products and cause serious fouling. Based on the high-temperature SiO2-P2O5 and CaO-SiO2-P2O5 phase diagram analysis, the control of Si/Ca molar ratio (e.g., Si/Ca = 2.0) was found to avoid fouling formation in the kiln. These results could provide the operation parameters of reaction temperature and feeds composition to suppress the fouling in the kiln reactor for the phosphoric acid production in industry.

Key words: Thermal phosphoric acid, Kiln technology, Fouling formation, Phase diagram analysis

摘要: Kiln phosphoric acid (KPA) technology could produce P2O5 with high purity and has been applied in thermal phosphoric acid industry; however the formation of fouling in the high-temperature rotary kiln restricts the stable and long-term operation. In this paper, the reaction of phosphate ores with gaseous P2O5 was investigated in a high-temperature reactor, and the CaO-SiO2-P2O5 ternary phase diagram was analyzed to understand the fouling formation mechanism. The results showed that the low-melting-point products, such as Ca(PO3)2 and Ca2P2O7, are responsible for the fouling in the KPA process. In addition, a small amount of impurities, e.g., aluminum and iron, could facilitate the generation of the low-melting-point products and cause serious fouling. Based on the high-temperature SiO2-P2O5 and CaO-SiO2-P2O5 phase diagram analysis, the control of Si/Ca molar ratio (e.g., Si/Ca = 2.0) was found to avoid fouling formation in the kiln. These results could provide the operation parameters of reaction temperature and feeds composition to suppress the fouling in the kiln reactor for the phosphoric acid production in industry.

关键词: Thermal phosphoric acid, Kiln technology, Fouling formation, Phase diagram analysis