磷石膏中微量含氟物相的光谱分析

磷石膏中二水硫酸钙(CaSO₄·2H₂O)的含量高达90%以上，是一种重要的再生石膏资源。然而与天然石膏不同，磷石膏中磷、氟、有机物等有害杂质限制了它的实际利用。探明微量杂质氟物相的存在形态、含量及分布规律，对高效脱除磷石膏中杂质氟具有重要的理论价值。采用X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)与电子显微探针(electron microprobe analysis, EMPA)相结合的分析方法，研究了磷石膏中微量含氟物相的主要存在形式和分布规律。结果表明，磷石膏中微量含氟物相主要包括NaF，KF，CaF₂，K₂SiF₆，Na₂SiF₆，Na₃AlF₆，K₃AlF₆，AlF₃·3H₂O，AlF_2.3(OH)_0.7·H₂O，Ca₅(PO₄)₃F，Ca₁₀(PO₄)₆F₂。其中，4.83%的氟以NaF，KF，CaF₂等氟化物形式存在，8.42%的氟以氟磷酸盐Ca₅(PO₄)₃F和Ca₁₀(PO₄)₆F₂形式存在，12.21%的氟以氟铝酸盐Na₃AlF₆和K₃AlF₆形式存在，41.52%的氟以氟硅酸盐K₂SiF₆和Na₂SiF₆形式存在，33.02%的氟以带结晶水的氟化铝AlF₃·3H₂O和AlF_2.3(OH)_0.7·H₂O形式存在。研究表明分析固体样品中微量元素物相时，采用XPS与EMPA相结合的分析方法更具有优势。本研究为磷石膏中微量杂质氟的脱除以及有效回收氟资源提供理论依据。

Spectral Analysis of Trace Fluorine Phase in Phosphogypsum

Phosphogypsum, which contains more than 90% of the calcium sulfate dihydrate(CaSO₄·2H₂O), is a kind of important renewable gypsum resources. Unlike the natural gypsum, however, phosphorus, fluorine, organic matter and other harmful impurities in phosphogypsum limit its practical use. To ascertain the existence form, content and phase distribution of trace fluoride in phosphogypsum has important theoretical values in removing trace fluoride effectively. In this present paper, the main existence form and phase distribution of trace fluoride in phosphogypsum was investigated by the combination of X-ray photoelectron spectroscopy (XPS) and Electron microprobe analysis (EMPA). The results show that trace fluoride phase mainly includes NaF, KF, CaF₂, K₂SiF₆, Na₂SiF₆, Na₃AlF₆, K₃AlF₆, AlF₃·3H₂O, AlF_2.3(OH)_0.7·H₂O, Ca₅(PO₄)₃F, Ca₁₀(PO₄)₆F₂. Among them, 4.83% of fluorine exists in the form of fluoride (NaF, KF, CaF₂); Accordingly, 8.43% in the form of fluoride phosphate(Ca₅(PO₄)₃F, Ca₁₀(PO₄)₆F₂); 12.21% in the form of fluorine aluminate(Na₃AlF₆, K₃AlF₆); 41.52% in the form of fluorosilicate(K₂SiF₆, Na₂SiF₆); 33.02% in the form of aluminum fluoride with crystal water(AlF₃·3H₂O, AlF_2.3(OH)_0.7·H₂O). In the analysis of phase constitution for trace elements in solid samples, the method of combining XPS and EMPA has more advantages. This study also provides theoretical basis for the removal of trace fluorine impurity and the effective recovery of fluorine resources.