磷矿浮选尾矿在硫磷混酸中的分解动力学研究

Dissolution Kinetics of Phosphorite Flotation Tailings by Mixture of Sulfuric Acid and Phosphoric Acid

对硫磷混酸分解磷矿浮选尾矿的动力学进行了研究,结果表明,随着反应温度和P2O5浓度的提高,尾矿中MgO和P2O5的浸出率提高,在相同条件下,MgO浸出率高于P2O5浸出率,且由于磷酸的加入,生成了溶解度较大的Ca(H2PO4)2,降低了硫酸钙固体膜层的影响,有效改善了反应物和生成物通过固体膜层的扩散过程.硫磷混酸分解磷矿浮选尾矿的动力学,可用形成致密固体反应物膜的收缩未反应核模型来描述,动力学模型与实验结果拟合直线的相关系数均在0.97以上.通过Arrhenius方程计算,MgO的表观活化能为9.95kJ/mol,P2O5的为12.84kJ/mol,说明硫磷混酸分解磷矿浮选尾矿容易进行,也说明酸解过程属于扩散控制过程.

The dissolution kinetics of phosphorite flotation tailings in the mixture of sulfuric acid and phosphoric acid was studied. The results showed that the leaching rates of MgO and P2O5 were improved with the increase of reaction temperature and P2O5 concentration. The leaching rate of MgO was higher than that of P2O5 under the same conditions. The reaction rate of dolomite with acid was faster than that of apatite with acid. Moreover,due to the addition of phosphoric acid,Ca(H2PO4)2 which has higher solubility than CaSO4-nH2O was produced to decrease the effect of solid layer of calcium sulphate on diffusion process. The dissolution kinetics could be described by the unreacted core shrinking model of producing solid outgrowth layer. The correlation coefficient fitting experimental data was more than 0.97. The reaction apparent activation energy of MgO calculated by Arrhenius equation was 9.95 kJ/mol,and that of P2O5 was 12.84 kJ/mol. The results showed that the dissolution reaction easily happened and was a diffusion control process.