首页|Deep decalcification of factory-provided freezing acidolysis solution to achieve α-high-strength gypsum

Deep decalcification of factory-provided freezing acidolysis solution to achieve α-high-strength gypsum

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The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,based on the potential crystallization principle of calcium sulfate in NH4NO3-H3PO4-H2O,the deep decalcification(i.e.calcium removal)technology to achieve α-high-strength gypsum originated from freezing acidolysis-solutions has been firstly proposed and investigated.Typically,calcium can be removed from the factory-provided freezing acidolysis-solution by neutralizing it with ammonia,fol-lowed by the addition of ammonium sulfate solution.As a result,the formation of calcium sulfate in the reaction system undergoes the nucleation and growth of CaSO4·2H2O(DH),as well as its dissolution and crystallization into short columnar α-CaSO4·0.5H2O(α-HH).Remarkably,with the molar ratio of SO24-/Ca2+at 1.8,the degree of neutralization(NH3/HNO3 molar ratio)at 1.7,the reaction temperature of 94 ℃,and the reaction time of 300 min,the decalcification rate can reach 86.89％,of which the high-strength α-CaSO4·0.5H2O(α-HH)will be obtained.Noteworthy,the deep decalcification product meets the standards for the production of fine phosphates and highly water-soluble phosphate fertilizers.Consequently,the 2 h flexural strength of α-HH is 5.3 MPa and the dry compressive strength is 36.8 MPa,which is up to the standard of commercial α-HH.

NitrophosphateAmmonia neutralizationDeep decalcificationHigh-strength α-hemihydrate gypsumControlled crystallization at atmospheric pressure

Wencai Ye、Yulu Li、Yonggang Dong、Lin Yang、Yun Yi、Jianxin Cao

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School of Chemistry and Chemical Engineering,Guizhou University,Guiyang 550025,China

Key Laboratory of Guizhou Province for Green Chemical Industry and Clean Energy Technology,Guizhou University,Guiyang 550025,China

Engineering Research Center of Efficient Utilization for Industrial Waste,Guizhou University,Guiyang 550025,China

National Key Research and Development Program of ChinaScience &Technology Plan Projects of Guizhou ProvinceScience and Technology Support Plan Project of Guizhou Provincial

2018YFC1900206-2Qiankehe Service Enterprises[2018]4011Qiankehe Support[2021]General 487

2024

10.1016/j.cjche.2024.01.015

中国化学工程学报(英文版)
中国化工学会

中国化学工程学报(英文版)

CSTPCDEI
影响因子：0.818
ISSN：1004-9541
年,卷(期)：2024.69(5)
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