热硫化条件下铁硫比值对黄铁矿形成的影响

模拟火山喷气成矿作用，在热硫化条件下，系统考察反应物中铁硫比值从Fe∶S=1∶1至1∶8变化对黄铁矿形成的影响。运用扫描电镜(SEM)、X射线粉晶衍射分析(XRD)等测试手段，观测和分析实验产物的形貌、成分和结构特征，发现随着Fe∶S比值的减小，实验产物中黄铁矿逐渐增多，磁黄铁矿逐渐减少，同时Fe∶S比值对实验产物的形貌也有一定的控制作用。计算结果显示实验产物中黄铁矿晶粒尺寸的变化范围为42.543~63.799 nm，磁黄铁矿晶粒尺寸的变化范围为21.973~87.926 nm，黄铁矿和磁黄铁矿的晶胞体积变化较小。结合热力学计算结果分析认为，在热硫化条件下，当Fe∶S比值小于或等于磁黄铁矿中铁硫原子比时，反应生成磁黄铁矿；当Fe∶S比值超过磁黄铁矿中铁硫原子比时，实验产物中出现黄铁矿；当Fe∶S比值达到或超过黄铁矿中铁硫原子比时，反应主要生成黄铁矿。过硫条件有利于黄铁矿的生长，硫源越充足，实验产物中黄铁矿越多。

The influence of different iron-sulfur ratios on pyrite formation under thermal sulfurization condition

In the course of simulating the volcanic exhalation mineralization,the impact of different iron-sulfur ratio from Fe∶S=1∶1 to 1∶8 on pyrite formation was investigated under the thermal sulfurization condition.By using scanning electron microscopy(SEM),powder X-ray diffraction(XRD) and other methods,the morphological,compositional and structural characteristics of the experimental products were observed and analyzed.With the Fe∶S ratio decreasing,the pyrite gradually increased and the pyrrhotite gradually reduced.The iron-sulfur ratio also had a certain impact on the crystal morphology of experimental products.After calculating,the pyrite grain size ranged from 42.543 nm to 63.799 nm,the pyrrhotite grain size ranged from 21.973 nm to 87.926 nm,and the unit cell volume of the pyrite and pyrrhotite changed a little.Combined with the thermodynamic analysis,under the thermal sulfurization condition,when the Fe∶S ratio was less than or equal to the iron-sulfur atomic ratio of pyrrhotite,the reaction produced pyrrhotite;when the Fe∶S ratio reached the iron-sulfur atomic ratio of pyrite,the pyrite appeared;when the Fe∶S ratio reached or exceeded the iron-sulfur atomic ratio of pyrite,the reaction mainly produced pyrite.The excessive sulfur condition was conducive to pyrite formation.The more adequate of sulfur source,the more percentage of pyrite would produce in the products.