关键词: 石英砂;焙烧;酸洗;Fe杂质;未反应核模型

Abstract: A method for removing iron impurity from silica sand by roasting and acid leaching was proposed .The optimum holding time is 180 min under the roasting temperature of 900 ℃.The iron content in silica sand with roasting is 34.61 μg/g, the removal rate is 88.3％after acid leaching under conditions:acid leaching temperature is 90 ℃, leaching time is 360 min.The silica sand was analyzed by SEM, the corresponding result showed that there are many cracks and corrosion pits on the surface of the silica sand particles after roasting , which contributed to removing of Fe impurity .Kinetics analysis reveals that the product layer diffusion in heterogeneous reaction system is the rate-controlling step . Compared to the one without roasting , the acid leaching after roasting reacts more quickly , the iron content and the activation energy are lower .The activation energy is 30.88 kJ/mol after roasting for 900℃, holding 180 min compared with 36 .18 kJ/mol without roasting , and it reduce 17 .2％after roasting . It showed that roasting will promote the acid leaching reaction .

Key words: silica sand;roasting;acid leaching;iron impurity;shrinking core model