白钨矿与萤石、方解石电子结构的第一性原理研究

First-Principle Theory Calculation of Electronic Structures of Scheelite,Fluorite and Calcite

采用基于密度泛函理论的第一性原理,计算了理想白钨矿、萤石和方解石的电子结构,及水分子和聚丙烯酸钠在3种矿物表面吸附的吸附能,并采用单矿物浮选试验验证了水体系中聚丙烯酸钠在3种矿物表面的吸附能的关系。计算结果表明:白钨矿、萤石和方解石的优化都采用局域密度泛函近似(LDA)下的CA-PZ交换相关函数,截断能分别为277,270和275 e V;能带结构表明3种矿物均属于绝缘体,其Ca原子态密度组成很相似,因此化学活性非常相似,在浮选过程中表现出相似的浮选性能;Mulliken布居分析表明3种矿物Ca原子所带电荷大小顺序为方解石>白钨矿>萤石。在矿浆中聚丙烯酸钠排开矿物表面的水分子与矿物发生吸附,其吸附能均为负值,大小顺序为白钨矿>方解石>萤石,说明自然p H(未添加p H调整剂)条件下聚丙烯酸钠对3种矿物有抑制作用,抑制强弱为萤石>方解石>白钨矿。单矿物浮选试验结果表明,聚丙烯酸钠为抑制剂时,在自然p H条件下,白钨矿、萤石和方解石的回收率分别为76.03%,18.59%和33.68%,此时聚丙烯酸钠的抑制强弱顺序为萤石>方解石>白钨矿,与计算模拟结果相符。为进一步了解白钨矿、萤石和方解石可浮性的差异及含钙矿物浮选新药剂开发提供理论参考。

The electronic structures of scheelite,fluorite and calcite and the adsorption energy of H2 O and PA-Na adsorbing on the three kinds of mineral surface were calculated using first-principle method based on the density functional theory（ DFT）. Single mineral flotation tests verified the adsorption energy relationship of PA-Na attached to minerals in the water system. The calculation results showed that exchange / correlation function（ CA-PA） of local-density approximation（ LDA） was used to optimize electronic structures of scheelite,fluorite and calcite,and cut-off energies were 277,270 and 275 e V,respectively. Energy band structures showed that the three minerals were all insulators and their densities of Ca were similar extremely. Their chemical activities were very similar,so that the minerals showed similar flotation performance. The Mulliken population analysis showed that the charge of Ca of the three mineralswas as follows： calcite scheelite fluorite. Sodium polyacrylate（ PA-Na） was absorbed on mineral surfaces when H2 O molecules were released in the pulp,and the adsorption energies were negative in the order of scheelite calcite fluorite. This showed that PANa could inhibit the three minerals in the order of fluorite calcite scheelite at the nature p H（ p H adjusting agent was not added）.Single mineral flotation test results showed that as an inhibitor of PA-Na,the recoveries of scheelite,fluorite and calcite were 76. 03%,18. 59% and 33. 68%,respectively,at the nature p H. The inhibiting ability of PA-Na was in the order of fluorite calcite scheelite,which was consistent with the calculation results. This work provided a theoretical reference for the research on flotation performances of calcite,scheelite and fluorite and the development reagents.