菱镁矿和白云石的表面性质及浮游性的密度泛函理论研究

菱镁矿是一种重要的含镁矿物,是制取金属镁的主要原料,菱镁矿和白云石的分离是使用浮选法富集菱镁矿的关键问题之一。矿物表面润湿性的调节是浮选过程中的核心问题,与矿物的表面性质密切相关,深入了解这两种矿物的表面性质,对研究菱镁矿和白云石的浮选分离具有重要意义。本文采用基于密度泛函理论的第一性原理计算方法,研究菱镁矿和白云石两种矿物解理面的性质及其与两种矿物浮游性之间的关系。结果表明:当矿物晶体破裂后,两种矿物的表面均出现明显的重构现象,白云石表面原子的弛豫现象比菱镁矿更明显;白云石(101)面的表面自由能小于菱镁矿(101)面的表面自由能;两种矿物表面Mg原子的3s轨道和2p轨道电子以及Ca原子的3s轨道电子的轨道能级均跨越费米能级;两种矿物(101)表面均具有较强的离子性。

Density functional theory study on surface properties and floatability of magnesite and dolomite

Magnesite is an important magnesium-bearing mineral and is the main raw material for the production of magnesium. The adjustment of mineral surface wettability is a core issue in the flotation process, which is closely related to the surface properties of minerals. Therefore, an in-depth understanding of the surface properties of magnesite and dolomite is of great significance for their flotation separation. In this paper, the first-principles calculation method based on density functional theory (DFT) is used to study the properties of the cleavage planes of magnesite and dolomite, and its relationship with the floatability of two minerals. The results show that when the mineral crystals rupture, the surface structure of the two minerals shows obvious reconstruction. The relaxation of the dolomite surface atoms is more obvious than that of magnesite. The surface free energy of the dolomite (101) surface is smaller than that of the magnesite (101) surface. The orbital energy of the 3s orbital and 2p orbital electrons of the Mg atoms and the 3s orbital electrons of the Ca atom on the surface of the two minerals all span the Fermi level. The surface of the two minerals (101) shows a strong ionicity.