Affiliations: [a] School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, P.R. China | [b] School of Foreign Languages, Wuhan Institute of Technology, Wuhan, P.R. China | [c] School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, P.R. China | [d] Key Laboratory of Solid Waste Treatment and Resource Recycle Ministry of Education, Southwest University of Science and Technology, Mianyang, P.R. China
Correspondence:
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Corresponding author: Li Liang, School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, P.R. China. E-mail: [email protected].
Abstract: To increase the production of potash, it is important to convert insoluble potassium-rich minerals into soluble potash salt efficiently. This paper focused on the extraction of soluble potassium from potassium feldspar with normal pressure and negative pressure in the reaction system of hydrofluoric acid–sulfuric acid. The mineralogy of the crude potassium feldspar was studied by X-Ray Fluorescence (XRF) and X-ray Diffraction (XRD) analyses. Factors of ammonium fluoride dosage, reaction time and system pressure on extraction efficiency of soluble potassium were investigated and system pressure is emphasized. The results shows that the dissolution rate of potassium was 79.3 wt.% with 0.5 g·g–1 ammonium fluoride for 2 h at atmospheric pressure. The dissolution rate was 93.1 wt.% at combined normal pressure for 1.5 h with negative pressure (–0.06 Mpa) for 0.5 h, which increased 13.87 wt.% for the extraction efficiency of soluble potassium. The dissolution mechanism was revealed by the thermodynamics calculation of potassium feldspar and demonstrated by phase identification and morphology of extraction residue using XRD. The process is novel method to extracted a large amount of soluble potassium from potassium feldspar which belongs to a simple, economical and effective chemical extraction method.
