钠长石的晶体化学基因特征及其可浮性预测

Crystal Chemical Genes Characteristics of Albite and Prediction of Its Floatability

基于密度泛函理论的第一性原理,采用Materials Studio软件的CASTEP模块对钠长石晶胞进行优化。计算结果表明:优化采用交换相关泛函为GGA-PBESOL,k点取样密度为2×2×4,平面波截断能为700 eV。Mulliken电荷布居表明钠长石中,O原子为电子受体,其余原子均为电子供体;Mulliken键布居表明Na-O键最易断裂,Na^+会溶于水而使钠长石表面荷负电,易与阳离子捕收剂发生作用;能带结构表明钠长石为绝缘体;态密度分析表明费米能级附近主要是由O原子的2p轨道贡献,所以O原子在参与化学反应时活性较强,是矿物浮选的活性位点;构建钠长石(010)表面,原子层数为3、真空层厚度为1.5 nm,表面Mulliken键布居与体相键布居有明显差别,计算得此时表面能为1.309 7 J/m^2。研究结果可以从微观层面为锂辉石与钠长石的浮选分离提供理论参考。

Based on the first principle of the density functional theory(DFT),the CASTEP module of Materials Studio was used to optimize the albite crystal cell.The parameters of optimization were set as that the exchange correlation function⁃al was GGA-PBESOL,the Brillouin zone was sampled using Monkhorst and Pack special k points of a 2×2×4 grid,and the plane wave cut-off energy was 700 eV.Mulliken charge population showed that O atom was electron acceptor and the rest at⁃oms were electron donors.Mulliken bond population indicated that Na-O bond was the easiest to break,Na+would dissolve in water and made the surface of albite negatively charged,which was easy to be acted by cation collector.Energy band struc⁃ture showed that albite was an insulator.Analysis of the density of states showed that the density of state near Fermi energy level was mainly attributed to 2p orbit of O,so the activity of the O atom was strong when it participated in the chemical reac⁃tion and it was the active site of mineral flotation.The albite(010)surface was selected to studied,and the atomic layers were 3 and the thickness of the vacuum layer was 1.5 nm,there were obvious differences of Mulliken bond population be⁃tween surface system and bulk system,and the surface energy was calculated to be 1.3097 J/m2.The results can provide the⁃oretical reference for flotation separation of spodumene from albite from the crystal chemical characteristics.