Recovery of Potassium from K-Feldspar by Thermal Decomposition with Flue Gas Desulfurization Gypsum and CaCO3: Analysis of Mechanism and Kinetics

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• 作者：Yiwei ZhongJintao Gao ; Panze Chen ; Zhancheng Guo
• 刊名：Energy & Fuels
• 出版年：2017
• 出版时间：January 19, 2017
• 年：2017
• 卷：31
• 期：1
• 页码：699-707
• 全文大小：601K
• ISSN：1520-5029

文摘

The thermal decomposition mechanism of K-feldspar with industrial waste of FGD gypsum to produce soluble potassium (K) salt was investigated. Effects of the reaction temperature and the amount of reagents used on the recovery of K were studied. The results showed that increasing the reaction temperature and mass ratio of CaCO₃/KAlSi₃O₈ and CaSO₄/KAlSi₃O₈ was beneficial to the decomposition of K-feldspar. The recovery ratio of K was higher than 90% with the mass ratio of KAlSi₃O₈:CaSO₄:CaCO₃ = 1:1:3 at 1373 K for 40 min, and the product K₂SO₄ with a purity of 91.3% was obtained. A crystal structure disintegration mechanism for KAlSi₃O₈ was proposed on the basis of the characterization of phase transformation sequences by XRD, FTIR, and SEM/EDS. It was found that two product layers formed successively during the KAlSi₃O₈ decomposition process. K was enriched in the outer product layer, and the decomposition rate was controlled by Ca diffusion through the inner one. Based on the experimental results, a kinetics model of K-feldspar decomposition was established using the Crank-Ginstling-Brounshtein equation, and the apparent activation energy was determined.