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

doi:10.1016/j.cjche.2020.01.005

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 Liu^1,2, Hairong Yue^1,2, Wei Jiang¹, Bin Liang^1,2

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 Liu^1,2, Hairong Yue^1,2, Wei Jiang¹, Bin Liang^1,2

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

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

Pan Wu, Li Lü, Siyang Tang, Changjun Liu, Hairong Yue, Wei Jiang, Bin Liang. The fouling properties of SiO₂-CaO-P₂O₅ system in high-temperature rotary kiln phosphoric acid process[J]. Chinese Journal of Chemical Engineering, 2020, 28(7): 1824-1831.

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

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

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