不同粒级辉钼矿的XRD和SEM及其可浮性差异研究

在浮选过程中，微细粒级的辉钼矿回收难度较大，易损失在尾矿中。为了分析不同粒级辉钼矿可浮性差异，揭示细粒级辉钼矿可浮性恶化的原因，以-150+74，-74+45，-45+38和-38 μm四个粒级辉钼矿为研究对象，通过辉钼矿纯矿物浮选试验，首次利用X射线衍射分析(XRD)、扫描电镜(SEM)及能谱(EDS)分析，对四个粒级辉钼矿的可浮性及其晶型特征和外在形貌的变化规律进行系统研究和对比。研究表明：随着粒级的减小，辉钼矿的可浮性降低，浮选效果恶化，且辉钼矿的可浮性由非极性、低能、疏水的“面”和活泼、亲水的“棱”的面积比决定。辉钼矿在受外力作用下由粗粒级变成细粒级过程中，首先主要是沿解理面破裂，然后沿断裂面的破裂增多，导致面棱比减小，辉钼矿的可浮性下降；同时辉钼矿晶型结构由3R亚稳定状态转变为2H型稳定状态。此外，与3R型的粗粒级辉钼矿相比，微细粒级辉钼矿以2H型为主，且其（002）晶面的面间距逐渐增大，导致水分子容易进入晶体结构内部，并在矿物表面形成水化膜，辉钼矿亲水性增强。晶型的不同使不同粒级辉钼矿的物理性质发生变化，面间距的增大则使辉钼矿断裂面暴露的亲水性钼-硫键数目增多，两者是细粒级辉钼矿亲水性增强及可浮性下降的本质原因。

XRD and SEM Analyses of Molybdenite with Different Particle Sizes and Its Floatability Difference

In the process of flotation, the recovery of micro-particle molybdenite is difficult, and it is easy to lose in the tailings. In order to analyze the flotability difference of molybdenite with different particle sizes and to reveal the reasons for the flotability of fine-grained molybdenite, using four particle sizes molybdenite respectively -150+74, -74+45, -45+38 and -38 μm as the research object, through molybdenite flotation tests of pure minerals, first by means of X ray diffraction analysis (XRD) and scanning electron microscopy (SEM) analysis，the floatability of particle size molybdenite and its crystalline characteristics, external morphology and variation were systematically studied and compared. The results showed that the floatability of molybdenite decreased with the decrease of particle size, and the flotation effect deteriorated. The floatability of molybdenite was determined by the area ratio of non-polar, low energy, hydrophobic “surface”and lively, hydrophilic “edge”. In the process of transformation from coarse to fine particle size under the action of external force, firstly, it mainly broke along the cleavage plane, and then broke more along the fracture surface, resulting in the decrease of the area ratio of “surface” and “edge”, and the decrease of the floatability. Meanwhile, the crystalline structure of molybdenite changed from 3R type to 2H type. In addition, compared with 3R type coarse particle size molybdenite, fine particle size molybdenite was mainly 2H type and the surface spacing of (002) crystal surface increased gradually. So water molecules was easy to enter the crystal structure and formed hydrated film on the mineral surface, resulting in an increase of the hydrophilicity of molybdenite. The physical properties of molybdenite with different particle sizes changed by different crystal types. The increase of the distance between the surfaces made the number of hydrophilic molybdenum sulfur bonds exposed to the fracture surface of molybdenite increase, which was the essential reason for the enhancement of hydrophilicity and the decrease of floatability of fine grained molybdenite.