Solid − liquid phase diagram of the KNO3 - Ca(NO3)2 - Mg(NO3)2 - H2O system at 313.15 K

IF 3.7 3区工程技术 Q2 ENGINEERING, CHEMICAL

Chinese Journal of Chemical Engineering Pub Date : 2025-02-01 DOI:10.1016/j.cjche.2024.11.002

Xiangxia Zeng, Tao Zhang, Li Lv, Wenxiang Tang, Zongpeng Zou, Shengwei Tang

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引用次数: 0

Abstract

The enrichment of low-grade phosphate rock is an important process to realize sustainable support of phosphorus resources. An aqueous solution containing Ca(NO₃)₂ and Mg(NO₃)₂ is produced during the enrichment of low-grade phosphate rock by leaching of HNO₃ or calcination coupling with leaching of NH₄NO₃ solution. Preparation liquid fertilizer is a preferential way to utilize it. The liquid−solid phase diagrams of Ca(NO₃)₂-Mg(NO₃)₂-H₂O, KNO₃-Mg(NO₃)₂-H₂O, KNO₃-Ca(NO₃)₂-H₂O and KNO₃-Ca(NO₃)₂-Mg(NO₃)₂-H₂O systems at 313.15 K were studied by isothermal dissolution equilibrium method. Two crystallization regions of Ca(NO₃)₂·4H₂O and Mg(NO₃)₂·6H₂O were observed in the phase diagram of the ternary system Ca(NO₃)₂-Mg(NO₃)₂-H₂O, a liquid fertilizer with a maximal total nutrient content of 27.46% and a nutrients ratio of N:Ca:Mg = 8.40:10.37:1 can be formed. A homogenous solution can be formed by mixing Ca(NO₃)₂·4H₂O and Mg(NO₃)₂·6H₂O. In the ternary system KNO₃-Mg(NO₃)₂-H₂O, the crystallization regions of KNO₃, Mg(NO₃)₂·6H₂O and the co-crystallization region of KNO₃ and Mg(NO₃)₂·6H₂O were observed. The obtained maximal total nutrient content of liquid fertilizer is 23.32% with the ratio of N:K₂O = 1:3.39. In the ternary system KNO₃-Ca(NO₃)₂-H₂O, the crystallization regions of Ca(NO₃)₂·4H₂O and KNO₃ were observed. The obtained maximal total nutrient content of liquid fertilizer is 38.41% with the ratio of N:K₂O:Ca = 1.05:1.18:1. A homogenous solution can also be formed by mixing Ca(NO₃)₂·4H₂O and KNO₃ directly. In the quaternary system KNO₃-Ca(NO₃)₂-Mg(NO₃)₂-H₂O, the crystallization regions of Ca(NO₃)₂·4H₂O, Mg(NO₃)₂·6H₂O and KNO₃ and the co-crystallization region of KNO₃ and Mg(NO₃)₂·6H₂O were observed. The obtained maximal total nutrient content of liquid fertilizer is 38.41% with the ratio of N:K₂O:Ca = 1.05:1.18:1. The modified BET model was successfully used to fit the solubility curves. The results can provide a guidance for the formulation of water-soluble fertilizers of N-(K, Ca, Mg).

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来源期刊

Chinese Journal of Chemical Engineering 工程技术-工程：化工

CiteScore

6.60

自引率

5.30%

发文量

4309

审稿时长

31 days

期刊介绍： The Chinese Journal of Chemical Engineering (Monthly, started in 1982) is the official journal of the Chemical Industry and Engineering Society of China and published by the Chemical Industry Press Co. Ltd. The aim of the journal is to develop the international exchange of scientific and technical information in the field of chemical engineering. It publishes original research papers that cover the major advancements and achievements in chemical engineering in China as well as some articles from overseas contributors. The topics of journal include chemical engineering, chemical technology, biochemical engineering, energy and environmental engineering and other relevant fields. Papers are published on the basis of their relevance to theoretical research, practical application or potential uses in the industry as Research Papers, Communications, Reviews and Perspectives. Prominent domestic and overseas chemical experts and scholars have been invited to form an International Advisory Board and the Editorial Committee. It enjoys recognition among Chinese academia and industry as a reliable source of information of what is going on in chemical engineering research, both domestic and abroad.