石英砂磁选—酸洗除铁机理研究

Iron Removal Mechnism of Silica Sand Purification by Magnetic Separation and Acid Leaching

为了提高石英砂的杂质去除率,采用磁选加混酸酸洗工艺,并研究了酸洗反应动力学模型,对石英砂酸浸除杂进行理论指导。试验结果表明,铁去除率随着粒径减小而增大,150~180μm石英砂磁选效果最好。通过研究不同酸洗组合,发现混酸(硝酸+盐酸+氢氟酸)对铁的去除效果最好;使用混酸(V_酸∶V_水=1∶1),90℃水浴反应360 min,石英砂中铁去除率可达88.3%,铁杂质含量降为24.76μg/g,达到了精制石英砂的纯度要求。利用液固多相未反应核模型拟合发现,石英砂的酸洗过程控速步骤为产物内扩散控制,计算得出反应激活能Ea=51.73 k J/mol。

In order to improve iron impurity removal efficiency of impurities from silica sand, magnetic separation and mixed acid leaching were used, and iron removing kinetic has been analyzed. The results show that iron removal rate is negative correlated with particle size and the removal rate of iron is the highest when the particle size is 150 ~ 180 μm. It is found that mixed acid （HNO3 ＋ HCl ＋ HF）has a better performance, and the removal rate can reach 88.3% ,the content of iron impurity is reduced to 24. 76 μg/g under conditions： Vacid：Vwater =1： 1, acid leaching temperature is 90 ℃, leaching time is 360 min. This meets the qualification of refined quartz sand. The kinetics analysis reveals that product layer diffusion in heterogeneous reaction system is the rate-control factor and the activation energy is 51.73 kJ/mol.