天然陈化对磷石膏理化性质的影响及作用机理研究

The effect and mechanism of natural aging procedure on the physicochemical properties of phosphogypsum

采用安徽某磷肥厂位于宁国市堆场的磷石膏为原料,探究不同天然陈化时间对磷石膏生料中杂质含量与理化性质的影响。通过测试与表征得出陈化0~3年磷石膏生料的杂质含量、品位、外观、微观形貌、晶体特性和分子结构在陈化过程中的变化。通过吉布斯自由能计算与X射线光电子能谱分析讨论了磷石膏中可溶磷、可溶氟、共晶磷在陈化过程中含量的降低机理。研究表明:陈化过程可以降低磷石膏中的杂质含量与粒径,但不会对微观形貌及晶体结构产生影响。此外,在陈化过程中,除了雨水冲刷对可溶性杂质的物理去除作用外,磷石膏内部会发生化学反应,从而达到固磷、固氟的作用。

In this paper,the phosphogypsum in Ningguo of an Anhui fertilizer industry has been employed as raw materials,which is utilized to explore the effects of different natural aging time on the impurity content and physicochemical properties of phosphogypsum.The changes of grade,appearance,impurities,micro-morphology,crystal characteristics and molecular structure of phosphogypsum during the natural aging process between 0~3 years have been analyzed.More importantly,the degradation mechanism of soluble phosphorus,soluble fluorine and eutectic phosphorus during the natural aging process has also been proposed by Gibbs free energy calculation and XPS analyzation.The results demonstrate that natural aging process can reduce the impurity content and particle size of phosphogypsum,but it will not affect the microstructure and crystal structure.Moreover,during the aging process,in addition to the physical removal of soluble impurities by rainwater erosion,chemical reactions have occurred inside of phosphogypsum during the natural aging process,which achieves effective phosphorus and fluorine fixation.