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人工晶体学报 ›› 2022, Vol. 51 ›› Issue (8): 1396-1405.

• 研究论文 • 上一篇    下一篇

F-及SiF2-6对α型半水硫酸钙结晶成核及形貌的影响

张远永1, 杨林1,2, 曹建新1,2, 刘荣1, 张煜1   

  1. 1.贵州大学化学与化工学院,贵阳 550025;
    2.贵州省工业废弃物高效利用工程研究中心,贵阳 550025
  • 收稿日期:2022-05-06 出版日期:2022-08-15 发布日期:2022-09-08
  • 通讯作者: 杨 林,教授。E-mail:ce.lyang@gzu.edu.cn
  • 作者简介:张远永(1995—),男,贵州省人,硕士研究生。E-mail:1017499611@qq.com
  • 基金资助:
    国家重点研发计划(2018YFC1900206-2);贵州省科技计划(黔科合平台人才[2019]5668号,黔科合平台人才[2019]5409号, 黔科合支撑[2021]一般487)

Effect of F- and SiF2-6 on the Crystallization Nucleation and Morphology of α-Hemihydrate Calcium Sulfate

ZHANG Yuanyong1, YANG Lin1,2, CAO Jianxin1,2, LIU Rong1, ZHANG Yu1   

  1. 1. School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China;
    2. Guizhou Engineering Research Center for Efficient Utilization of Industrial Waste, Guiyang 550025, China
  • Received:2022-05-06 Online:2022-08-15 Published:2022-09-08

摘要: 本文模拟了半水法湿法磷酸生产过程中α型半水硫酸钙(α-HH)的结晶过程。在30%P2O5,反应温度95 ℃,过饱和度S=1.64~2.10条件下,通过浊度仪监测溶液中浊度变化,测定了不同F-及SiF2-6浓度下α-HH结晶诱导时间,采用经典成核理论公式计算了α-HH的临界晶核半径及成核速率,并通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)表征分析了F-及SiF2-6对α-HH结晶过程的影响。结果表明:随着F-、SiF2-6浓度的升高,α-HH晶体的结晶诱导时间延长,表面能和临界晶核半径都增大,然而成核速率减小。当过饱和度S=1.64时,加入0.06 mol·L-1 F-,α-HH结晶诱导时间延长了465 s,成核速率减小到0.403×1029 晶核数·cm-3·s-1,然而,加入0.06 mol·L-1 SiF2-6,α-HH结晶诱导时间延长了710 s,成核速率减小到0.339×1029晶核数·cm-3·s-1。SiF2-6对α-HH晶体抑制成核作用大于F-。F-、SiF2-6阻碍了α-HH晶体沿C轴方向生长,使得晶体长径比减小,晶体形貌向短柱状变化。F-、SiF2-6影响了α-HH晶体(200)、(310)、(400)晶面衍射峰强度和结晶度。控制半水法湿法磷酸中F-及SiF2-6浓度水平,可以得到短柱状的α-HH晶体,有利于过滤洗涤。

关键词: α型半水硫酸钙, 结晶诱导时间, 临界晶核半径, 成核速率, 湿法磷酸, 表面能

Abstract: In this study, the crystallization process of type-α hemihydrate calcium sulfate (α-HH) in the hemihydrate wet-process phosphoric acid production was simulated. The crystallization induction time of α-HH was determined by monitoring the turbidity changes in 95 ℃, supersaturation from 1.64 to 2.10, 30%P2O5 phosphoric acid solution with different F- and SiF2-6 concentration. The critical nucleation radius and nucleation rates of α-HH were calculated by classical nucleation theory equations, and the effects of F- and SiF2-6 on the crystallization process of α-HH were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that with the increase of F- and SiF2-6 concentration, the crystallization induction time, the surface energy, and the critical nucleation radius of α-HH crystals increase, but the nucleation rates of α-HH crystals decrease. When 0.06 mol·L-1 F- is introduced in the system at the supersaturation 1.64, the crystallization induction time of α-HH crystals is prolonged by 465 s and the nucleation rate is reduced to 0.403×1029 crystal nuclei·cm-3·s-1. However, in the presence of 0.06 mol·L-1 SiF2-6, the crystallization induction time of α-HH crystals is prolonged by 710 s, and the nucleation rate is reduced to 0.339×1029 crystal nuclei·cm-3·s-1. The effect of SiF2-6 on nucleation inhibition of α-HH crystals is greater than that of F-. The F- and SiF2-6 hinder the growth of α-HH crystals along the C-axis, resulting in a decrease of the crystal aspect ratio and a change of the crystal morphology to short cylinder shape. F- and SiF2-6 affect the intensity and crystallinity of α-HH crystals (200), (310), (400) crystal planes. The concentration levels of F- and SiF2-6 in the semi-aqueous wet phosphoric acid are controlled to obtain short columnar α-HH crystals, which are favorable for filtration and washing.

Key words: type-α hemihydrate calcium sulfate, crystallization induction time, critical nucleation radius, nucleation rate, wet-process phosphoric acid, surface energy

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