磷石膏中可溶磷形态、分布及其对性能影响机制的研究

STUDY ON THE FORM AND DISTRIBUTION OF WATER-SOLUBLE P_2O_5 IN PHOSPHOGYPSUM AND EFFECTIVE MECHANISM OF PROPERTIES

可溶磷是磷石膏中主要有害杂质 .采用DSC ,SEM ,原子吸收光谱分析及结晶水测定 ,结合宏观性能试验 ,对可溶磷分布、形态及其对性能影响进行了研究 .结果表明 :可溶磷主要分布在二水石膏晶体表面 ,其含量随磷石膏粒度增加而增加 .可溶磷降低二水石膏脱水温度和液相过饱和度 ,使二水石膏晶体粗化 ,硬化体强度降低 .磷石膏胶结材水化时 ,可溶磷转化为Ca3 (PO4 ) 2 沉淀 ,覆盖在半水石膏晶体表面 ,阻碍其溶解与水化 ,使其缓凝 .不同形态可溶磷中 ,H3 PO4 对性能影响最大 .

Water_soluble P 2O 5 ia a main harmful impurity in phosphogypsum. By means of DSC, SEM, atom absorption spectra and constitution water, as well as the macro_property measurements, the forms and distributions of water_soluble P 2O 5 and its effects on the properties were studied. Experimental results show that water_soluble P 2O 5 is distributed on the surface of dihydrate gypsum crystals. Its content increases with increase of size of phosphogypsum. It reduces dehydration temperature and solubility of dihydrate gypsum, makes gypsum crystals thick and wide, and reduces the strength of hardened body. During phosphogypsum binder hydration, water_soluble phosphates become Ca 3(PO 4) 2 precipitate which covers the surface of CaSO 4·0.5H 2O crystals and hinders CaSO 4 · 0.5 H 2O to disso_ lve, hydrate and set. Among the different forms of water_soluble P 2O 5, the effects of H 3PO 4 are the worst.