锂辉石-氧化钙烧结法提锂的物相重构与动力学

对锂辉石-氧化钙烧结过程进行热力学分析，绘制了各反应Gibbs自由能与温度的关系图。结果表明，Al₂O₃会优先和Na₂O、Li₂O、K₂O反应，然后与CaO反应生成CaO·Al₂O₃，而且烧结温度需高于1060℃以保证LiAlSi₂O₆能够完成晶形转变。并探讨了锂辉石-氧化钙烧结法提锂的反应机理。考察了不同烧结条件对锂浸出率的影响并对熟料进行X射线衍射（XRD）分析表征。实验结果表明，在配料比为1∶1.25、烧结温度1150℃、烧结时间60min时，锂的浸出率达到92.14%，熟料中的主要物相为Ca₂SiO₄与LiAlO₂。利用XRD和扫描电镜-能谱联用仪（SEM-EDS）对熟料与浸出渣的物相、显微形貌及元素分布情况进行了分析表征。为了确定烧结反应的控制性步骤，在最优烧结条件的基础上对烧结过程进行动力学分析，结果表明，锂辉石-氧化钙烧结体系属于球形颗粒三维界面化学反应控制，烧结过程的动力学拟合方程为\mathrm{1}-{(\mathrm{1}-x)}^{\mathrm{1}/\mathrm{3}}=\mathrm{0.00677}t。

Phase reconstruction and kinetics of lithium extraction by spodumene-calcium oxide sintering process

In this paper, the thermodynamic analysis of spodumene-calcium oxide sintering process was carried out, and the relationship between Gibbs free energy and temperature was plotted. The results showed that the Al₂O₃ will react with Na₂O, Li₂O and K₂O first and then with CaO to form CaO·Al₂O₃. The sintering temperature was higher than 1060℃ to ensure that the LiAlSi₂O₆ can complete the crystal transition. The reaction mechanism of lithium extraction by spodumene-calcium oxide sintering method was discussed in detail. The effect of sintering conditions on the leaching rate of lithium was investigated and the clinker was characterized by XRD.The experimental results indicated that the leaching rate of lithium reached 92.14% when the mixture ratio was 1∶1.25 at the sintering temperature of 1150℃, and the sintering time of 60min. The main phases in clinker were Ca₂SiO₄ and LiAlO₂. The phase, microstructure and distribution of element of clinker and leaching slag were analyzed and characterized by XRD and SEM-EDS. In order to to determine the control step of the sintering process, the dynamic analysis of the sintering process was carried out on the basis of the optimized sintering conditions. The results showed that the spodumene-calcium oxide sintering system was chemical reaction control of the three-dimensional interface of the spherical particles, and the fitting equation of the kinetics of the sintering process was\mathrm{1}-{(\mathrm{1}-x)}^{\mathrm{1}/\mathrm{3}}=\mathrm{0.00677}\text{?}t.