Study on the Kinetics of Hydration Transformation from Hemihydrate Phosphogypsum to Dihydrate Phosphogypsum in Simulated Wet Process Phosphoric Acid,ACS Omega

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Study on the Kinetics of Hydration Transformation from Hemihydrate Phosphogypsum to Dihydrate Phosphogypsum in Simulated Wet Process Phosphoric Acid
ACS Omega ( IF 3.7 ) Pub Date : 2021-03-08 , DOI: 10.1021/acsomega.0c05432
Bingqi Wang _{1,

2} , Lin Yang _{1,

2} , Tong Luo _{1,

2} , Jianxin Cao _{1,

3}

Affiliation

The key technology of wet process phosphoric acid recrystallization is phosphogypsum phase transformation. In this study, the hydration of α-hemihydrate phosphogypsum (α-HH) to dihydrate phosphogypsum (DH) and the influence of process parameters on hydration kinetics are performed by modifying a dispersive kinetic model in the simulation of wet process phosphoric acid recrystallization. Results show that the modified dispersive kinetic model is very important in describing the entire kinetic process, indicating that α-HH–DH hydration includes induction of nucleation and growth restriction. The hydration rate of α-HH–DH substantially accelerates with the decrease of temperature and phosphoric acid concentration because the activation entropy of the reaction increases during the induction stage and the growth stage, which reduces the activation energy barrier. Moreover, the hydration rate of α-HH–DH considerably accelerates with the increase of SO₄^2– ion concentration. Activation entropy increases in the induction stage, causing the activation energy barrier to decrease. Activation enthalpy increases in the growth stage, causing the activation energy barrier to decrease. The influence of process parameters on the rate of the α-HH–DH hydration reaction follows the order SO₄^2– ion concentration > phosphoric acid concentration > temperature. Therefore, controlling the three parameters of temperature, phosphoric acid concentration, and SO₄^2– ion concentration are important for improving the conversion rate of α-HH–DH and the purity of DH products in the production of wet process phosphoric acid.

中文翻译：

模拟湿法磷酸中半水磷石膏水合转化为二水合磷酸酯的动力学研究

湿法磷酸重结晶的关键技术是磷石膏相变。在这项研究中，通过在湿法磷酸重结晶的模拟中修改分散动力学模型，进行了α-半水合磷酸石膏（α-HH）到二水合磷酸石膏（DH）的水合以及工艺参数对水合动力学的影响。结果表明，改进的分散动力学模型在描述整个动力学过程中非常重要，表明α-HH-DH水合包括诱导成核作用和生长限制。α-HH-DH的水合速率随着温度和磷酸浓度的降低而大大加快，因为反应的活化熵在诱导阶段和生长阶段增加，这减少了激活能垒。而且，随着SO的增加，α-HH-DH的水合速率大大加快。₄^{2 –}离子浓度。活化熵在诱导阶段增加，导致活化能垒降低。活化焓在生长阶段增加，导致活化能垒降低。工艺参数对α-HH-DH水合反应速率的影响遵循SO ₄^2–离子浓度>磷酸浓度>温度的顺序。因此，控制温度，磷酸浓度和SO ₄^2-离子浓度这三个参数对于提高湿法磷酸生产中α-HH-DH的转化率和DH产物的纯度至关重要。

更新日期：2021-03-23

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