Chinese Journal of Applied Chemistry ›› 2022, Vol. 39 ›› Issue (9): 1437-1446.DOI: 10.19894/j.issn.1000-0518.210544

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Effect of Chlorine Removal on Crystallization in the Mother Liquor of Ammonium Sulfate

Gao-Yong ZI1,2, Bang-Fu HUANG1,2(), Meng DAI1,2, Zheng-Yu YANG1,2, Zhen-Jing WEN1,2, Wan-Jun LI1,2, Liu-Bin LUO1,2   

  1. 1.Faculty of Metallurgical and Energy Engineering,Kunming University of Science and Technology,Kunming 650093,China
    2.Clean Metallurgy Key Laboratory of Complex Iron Resources,University of Yunnan Province,Kunming 650093,China
  • Received:2021-11-23 Accepted:2022-02-28 Published:2022-09-01 Online:2022-09-08
  • Contact: Bang-Fu HUANG
  • About author:kmusthbf@163.com
  • Supported by:
    the General Project of Applied Basic Research Program of Yunnan Province(202001AT070029);the Open Foundation of Key Laboratory of Iron and Steel Metallurgy and Resource Utilization of Ministry of Education(FMRUlab?20?4)

Abstract:

Continuous cyclic enrichment of Cl- in mother liquor of ammonium sulfate causes serious corrosion of equipment, while also affecting the crystallization and quality of ammonium sulfate. Dechlorination of the mother liquor of ammonium sulfate is investigated using calcium aluminum sulfate and desulfurized ash aluminum approach. A sieving approach is used to analyze the crystal size, scanning electron microscope is used to characterize the crystal size and morphology, and X-ray diffraction is used to analyze the crystal phase. The results show that the optimal dechlorination agent dosage is 3.0 g calcium sulfate and 0.8 g sodium metaaluminate, 3.0 g desulfurization ash and 0.8 g sodium metaaluminate, corresponding to dechlorination rates of 31.70% and 36.38%, respectively. At a rate of 200 r/min and a reaction temperature of 75 ℃, the addition of two dechlorinating agents causes the ρ(Cl-) to drop rapidly. The reaction of Cl- with Ca2+ and AlO2- forms insoluble calcium aluminum chloride compounds. Excessive NaAlO2 causes double hydrolysis, dissociates OH-, and inhibits the reaction of Cl- with Ca2+ and AlO2-, resulting in a decrease in the rate of Cl- removal. The calcium aluminum chloride compound forms using the calcium aluminum sulfate approach will adhere to the crystal grains′ active surface, thereby increasing the width of the ammonium sulfate crystal metastable zone, inhibiting the crystal′s normal growth, and reducing the number of crystals; the impurity metal in the desulfurization gray aluminum method can OH- consumption and reduction of the width of the metastable zone of ammonium sulfate crystals, containing a large amount of SO42- increases the amount of ammonium sulfate crystals, but reduce the crystal purity. The results of related studies can be used as a reference for reducing ammonia desulfurization equipment corrosion and enhancing ammonium sulfate crystallization.

Key words: Ammonium sulfate, Chlorine removal, Calcium aluminum sulfate method, Desulfurization ash aluminum method, Crystallization

CLC Number: