Microwave pretreatment of gold-bearing sulfides in an inert atmosphere has served as a promising technique to improve the extraction of gold. However, the complex decomposition mechanism of gold-bearing pyrite under microwave irradiation has not been completely clarified. This study employs in-situ and ex-situ X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) to investigate the phase transformation and sulfur conversion during microwave pyrolysis of gold-bearing pyrite. The removal of sulfur from gold-bearing pyrite caused a significant change at about 600 °C with an activation energy of 223.02 kJ·mol⁻¹. The phase transformation during in-situ heating of gold-bearing pyrite occurred at 500–600 °C, and the crystal lattices underwent thermal expansion along the c-axis direction. Under microwave irradiation, iron (Fe) and sulfur (S) atoms in pyrite rearranged themselves to form different types of pyrrhotite in space groups P31 and P63/mmc, and the symmetry of crystal structure became disordered. After microwave pyrolysis, the formation of polycrystalline aggregates consisting of nanoscale pyrrhotite and unreacted pyrite was confirmed in the TEM study. Microwave-induced hot spots should be responsible for the appearance of numerous holes inside mineral particles. Additionally, the sulfur in pyrite (S₂²⁻ and S_n²⁻) was converted to monosulfide (S²⁻) in pyrrhotite and elemental sulfur (S⁰), potentially reducing air pollution caused by exhaust emissions. This work provides further insights into the decomposition mechanism of gold-bearing pyrite in the microwave field, and it may help advance the application of microwave pretreatment under inert atmospheres in gold extraction.

在惰性气氛中微波预处理含金硫化物已成为改善金提取的有前途的技术。然而，微波辐照下含金黄铁矿的复杂分解机理尚未完全阐明。本研究采用原位和非原位 X 射线衍射 (XRD)、透射电子显微镜 (TEM) 和 X 射线光电子能谱 (XPS) 研究了含金黄铁矿微波热解过程中的相变和硫转化。 . 含金黄铁矿中硫的脱除在约 600 °C 时引起显着变化，活化能为 223.02 kJ·mol ^-1. 含金黄铁矿原位加热相变发生在500~600 ℃，晶格沿c轴方向发生热膨胀。在微波辐照下，黄铁矿中的铁（Fe）和硫（S）原子重新排列形成不同类型的空间群P31和P63/mmc的磁黄铁矿，晶体结构的对称性变得无序。在微波热解后，TEM 研究证实了由纳米级磁黄铁矿和未反应的黄铁矿组成的多晶聚集体的形成。微波引起的热点应该是矿物颗粒内部出现大量孔洞的原因。此外，黄铁矿中的硫（S ₂ ^2-和 S _n ^2-）转化为一硫化物（S ^2-) 在磁黄铁矿和元素硫 (S ⁰ ) 中，有可能减少废气排放造成的空气污染。该工作进一步深入了解了含金黄铁矿在微波场中的分解机理，有助于推进惰性气氛下的微波预处理在黄金提取中的应用。