黄铁矿晶体断裂机制与表面反应性研究

A study on the broken mechanism and surface reactivity of pyrite crystal

通过密度泛函理论、断裂键参数和晶体结构分析,本文研究了黄铁矿晶体各向异性、晶体断裂规律及表面反应性。研究结果表明,黄铁矿晶体中存在Fe—S和S—S两种化学键,且Fe—S键的键能高于S—S键。Fe—S键与S—S键强度不等导致晶面断裂键密度与表面能关系不显著。通过引入化学键能量参数,本文得出晶面断裂能密度更适合分析黄铁矿晶体断裂机制和预测表面能,进而从晶体化学的角度解释了黄铁矿(100)、(111)、(210)、(110)面的表面能及其在晶体断裂时出现的困难程度依次增加的趋势,同时明确了黄铁矿常见暴露面的位点配位性质。基于此,研究得出黄铁矿表面低配位数的位点活性相对较强,从晶体化学的角度阐述了含金黄铁矿具有良好可浮性以及黄铁矿不同晶面氧化性差异的机理。

The anisotropy,fracturing mechanism,and surface reactivity of pyrite crystal have been studied by using the density functional theory,broken bond parameters and crystal structure analysis.The results show that there are Fe—S and S—S bonds in pyrite crystals,and the bond energy of the Fe—S bond is greater than that of the S—S bond.The relationship between the surface energy of crystal plane and the density of broken bond is not obvious because of different strengths of the Fe—S bond and the S—S bond.By introducing the chemical bond energy parameter,it is obtained that the broken energy density of the crystal surface is more suitable for analyzing the fracturing mechanism of pyrite crystals and predicting the surface energy of pyrite.Then,the surface energies of the(100),(111),(210),and(110)planes of pyrite and the increasing tendency of difficulty for the occurrence of the crystal broken of pyrite have been explained from the perspective of crystal chemistry.The coordination properties of sites on common exposed surfaces of pyrite have also been determined.On the basis above,it is found that the sites on the surface of pyrite with low coordination numbers have relatively strong activities.The mechanisms of good floatability of gold-bearing pyrite and different oxidization properties of different pyrite crystal planes have been explained from the perspective of crystal chemistry.