黄铁矿加热过程中的矿相变化研究——基于磁化率随温度变化特征分析

对采自河南嵩县祁雨沟7号角砾岩筒的黄铁矿样品进行了详细的磁化率随温度变化特征研究，加热的最高温度为700℃，结果表明黄铁矿受热分解最终生成磁黄铁矿.黄铁矿通过两个可能的途径转变为磁黄铁矿：一个是黄铁矿颗粒首先经表面吸附氧的氧化转变为磁铁矿，随温度升高新生成的磁铁矿与黄铁矿晶格中挥发出的硫进一步反应转变为磁黄铁矿；另一可能途径是黄铁矿直接脱硫转变为磁黄铁矿，此反应为磁黄铁矿的主要来源.氩气环境下加热过程中，从约380℃开始即有磁铁矿生成，但直到约535℃才有磁黄铁矿的生成.在535℃～560℃的加热过程中生成的磁黄铁矿居里温度不稳定，直到加热至高于约560℃时才生成居里温度稳定的磁黄铁矿.氩气环境下，黄铁矿受热生成的磁性矿物的类型仅受最高温度的控制，与高温段的滞留时间无明显关系，而其生成量同时受最高温度和高温段滞留时间的控制.

Detection of mineralogical changes in pyrite using measurements of temperature-dependence susceptibilities

Detailed measurements of temperature_dependence susceptibilities were employed to detect mineralogical changes of pyrite samples from Song county, Henan Province. The results indicate that pyrite converts into pyrrhotite in either an argon or an air atmosphere through two possible processes. One is that magnetite firstly appears around the powder of pyrite by oxidation caused by oxygen adsorbed on the powder, and then the newly formed magnetite reacts with sulfur atoms which are released from the pyrite lattice and converts into pyrrhotite at higher temperature. The other is that pyrite directly transforms into pyrrhotite by desulphation, and this reaction is the main source of pyrrhotite in our experiments. During heating in an argon atmosphere, magnetite begins to occur at 380℃, while pyrrhotite does not occur until 535℃. When pyrite is heated to 535℃～560℃, the Curie temperature of the newly formed pyrrhotite is not stable, and the Curie temperature of newly formed pyrrhotite may tend to be stable when pyrite is heated to above about 560℃. The type of the newly formed magnetic minerals when pyrite is heated in an argon atmosphere only depends on the maximal temperature, and does not depend on the linger time at the maximal temperature, while the amount of the newly formed magnetic minerals is controlled by both these factors.