Ca （H2PO4） 2-H3PO4-K2SO4体系两步法制备KH2PO4过程中硫酸钙晶型和形貌调控

doi:10.3969/j.issn.1001-1803.2022.11.004

日用化学工业（中英文） ›› 2022, Vol. 52 ›› Issue (11): 1169-1178.doi: 10.3969/j.issn.1001-1803.2022.11.004

Ca （H₂PO₄） ₂-H₃PO₄-K₂SO₄体系两步法制备KH₂PO₄过程中硫酸钙晶型和形貌调控

叶文财^1,²,吴钦¹,易芸^1,²,于文³,曹建新^1,^2,^*()

1.贵州大学化学与化工学院，贵州贵阳 550025
2.贵州省绿色化工与清洁能源技术重点实验室，贵州贵阳 550025
3.贵州省建材产品质量检验检测院，贵州贵阳 550002

收稿日期:2022-07-11 修回日期:2022-10-28 出版日期:2022-11-22 发布日期:2022-11-22
通讯作者: 曹建新
基金资助:
国家重点研发计划(2018YFC1900206-2);贵州省科技计划项目(黔科合支撑[2021]一般487);贵州省科技计划项目(黔科合服企[2018]4011)

Regulation of crystal form and morphology of gypsum during two-step preparation of KH₂PO₄ via Ca（H₂PO₄） ₂-H₃PO₄-K₂SO₄ system

Ye Wencai^1,²,Wu Qin¹,Yi Yun^1,²,Yu Wen³,Cao Jianxin^1,^2,^*()

1. School of Chemistry and Chemical Engineering, Guizhou University, Guiyang, Guizhou 550025, China
2. Key Laboratory of Guizhou Province for Green Chemical Industry and Clean Energy Technology, Guizhou University, Guiyang, Guizhou 550025, China
3. Guizhou Provincial Building Materials Product Quality Inspection and Testing Institute, Guiyang, Guizhou 550002, China

Received:2022-07-11 Revised:2022-10-28 Online:2022-11-22 Published:2022-11-22
Contact: Jianxin Cao

摘要/Abstract

摘要：

在Ca（H₂PO₄）₂-H₃PO₄-K₂SO₄体系中，通过调控较低温度下CaSO₄·2H₂O结晶和较高温度下CaSO₄·2H₂O向CaSO₄·0.5H₂O转晶的两步法晶化反应，制备KH₂PO₄及副产品α型半水硫酸钙。研究了反应条件对两步晶化过程中CaSO₄晶型和形貌、磷钾收率和脱钙率的影响。结果表明，反应温度、反应时间、K₂SO₄溶液浓度、SO₄^2-过量系数、CaO/P₂O₅摩尔比和P₂O₅含量等参数的变化对CaSO₄晶型形貌、磷钾收率和脱钙率具有明显影响。一步反应和结晶温度为70 ℃、反应和结晶时间为60 min、二步转晶温度为102 ℃、转晶时间为5.0 h、K₂SO₄质量分数10%、SO₄^2-过量系数1.2、CaO/P₂O₅摩尔比0.20、P₂O₅质量分数25%条件下，滤液钾收率、磷收率和脱钙率分别达98.35%，91.43%和89.74%，制得石膏样品晶型为α-CaSO₄·0.5H₂O、形貌呈六棱形锥面短柱状、2 h抗折强度和绝干抗压强度分别达5.70 MPa和35.07 Mpa、强度等级达到JC/T 2038－2010《α型高强石膏》α30要求。制得的磷酸二氢钾纯度达80%以上。

关键词: Ca（H₂PO₄）₂-H₃PO₄-K₂SO₄体系, 一步结晶, 二步转晶

Abstract:

In Ca（H₂PO₄） ₂-H₃PO₄-K₂SO₄ system, α-calcium sulfate was made as a by-product during the production of KH₂PO₄through regulating the two-step crystallization reaction including the crystallization of CaSO₄·2H₂O at lower temperature and the crystal transformation from CaSO₄·2H₂O to CaSO₄·0.5H₂O at higher temperature. The effects of reaction conditions on the crystal formation and morphology of CaSO₄, the yields of phosphorus and potassium, and the decalcification rate in the two-step crystallization process were studied. The results showed that, the preparation parameters such as reaction temperature, reaction time, K₂SO₄ solution concentration, SO₄^2- excess coefficient, CaO/P₂O₅ molar ratio and P₂O₅ content significantly influenced the morphology of CaSO₄ crystal, the yields of phosphorus and potassium, and the decalcification rate. When the first-step reaction and crystallization was operated at 70 ℃ for 60 min and the second-step crystallization transformation was operated at 102 ℃ for 5.0 h under the conditions of K₂SO₄ concentration being 10%, SO₄^2- excess coefficient of 1.2, CaO/P₂O₅ ratio of 0.20 and P₂O₅ content of 25%, the yield of potassium and the yield of phosphorus and the decalcification rate of filtrate were 98.35%, 91.43% and 89.74%, respectively. The crystal form of the gypsum sample thus prepared was α-CaSO₄·0.5H₂O, and the morphology was hexagonal conical short column. The 2-hour-flexural-strength and absolute dry compressive strength reached 5.70 MPa and 35.07 MPa, respectively, which matched with the α30 level of the α-high-strength gypsum industry standard. The purity of the produced potassium dihydrogen phosphate was higher than 80%.

Key words: Ca（H₂PO₄）₂-H₃PO₄-K₂SO₄ system, one-step crystallization, two-step crystal transformation

中图分类号:

TQ177

叶文财,吴钦,易芸,于文,曹建新. Ca （H₂PO₄） ₂-H₃PO₄-K₂SO₄体系两步法制备KH₂PO₄过程中硫酸钙晶型和形貌调控[J]. 日用化学工业（中英文）, 2022, 52(11): 1169-1178.

Ye Wencai,Wu Qin,Yi Yun,Yu Wen,Cao Jianxin. Regulation of crystal form and morphology of gypsum during two-step preparation of KH₂PO₄ via Ca（H₂PO₄） ₂-H₃PO₄-K₂SO₄ system[J]. China Surfactant Detergent & Cosmetics, 2022, 52(11): 1169-1178.

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参考文献 14

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指标	初凝/min	终凝/min	2 h抗折/MPa	绝干抗压/MPa
JC/T 2038－2010	≥3	≤30	≥4.0（α30等级）	≥30.0（α30等级）
样品	12	27	5.7	35.07

Ca （H₂PO₄） ₂-H₃PO₄-K₂SO₄体系两步法制备KH₂PO₄过程中硫酸钙晶型和形貌调控

Regulation of crystal form and morphology of gypsum during two-step preparation of KH₂PO₄ via Ca（H₂PO₄） ₂-H₃PO₄-K₂SO₄ system

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