关键词: 浸取中和法, 磷石膏, 硫酸, 除杂

Abstract: The effects of temperature，time，and mass fraction of sulfuric acid on the removal of P，F，Fe2O3，and Al2O3 impurities from the phosphogypsum were investigated in the process of phosphogypsum leached by H2SO4 and the acidity was adjusted with lime milk.The microstructure，thermostability，and crystal structure of phosphogypsum before and after treatment were carefully analyzed by scanning electron microscope（SEM），thermogravimetric analysis（TG），and X ray diffraction （XRD）.Results showed that the optimum conditions as follows: the leaching temperature was 85 ℃，the leaching time was 45 min，the mass fraction of H2SO4was 30%.Under the optimal conditions，the removal percents of P and F were both achieved about 90%，Al2O3 removal rate was 80%，Fe2O3 removal rate was over 20%，and pH of phosphogypsum was at least 7.0. Phosphogypsum leached with H2SO4 showed sharply decreased particle size，but higher thermostability，and more stable structure.It was concluded that it could meet the requirements for the building materials.

Key words: leaching neutralization method, phosphogypsum, sulfuric acid, impurity removing