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对铜陵矿区废矿石的矿物组成及其成因进行研究,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分析原生矿物及其风化产物的组成,探讨次生矿物的形成机制。XRD及SEM/EDS分析表明,废矿石中残留的主要原生矿物为黄铁矿,次生矿物为针铁矿、赤铁矿、水铁矿及次生硫酸盐矿物。原生矿物风化为次生矿物的过程是从黄铁矿的裂隙带等有缺陷的部位开始,逐步氧化成最终产物针铁矿。中间过程出现了矿物相及形态的多样性,局部可能会先形成中间产物水铁矿,由于水铁矿很不稳定,在不同的温、湿度条件下会很快转化成针铁矿或赤铁矿。针铁矿在风化过程中呈现出多种形态,针状矿物最先形成,随后重结晶成球状集合体和菱方双锥单晶,最后在废矿石表面完全覆盖一层土状针铁矿。SEM观察到的黄铁矿表面的生物矿物与最外层风化层上的菌丝类物质说明,在废矿石的风化过程中生物亦起了一定的作用。
The mineral composition and genesis of waste ore in Tongling mining area were studied. The composition of primary minerals and their weathering products were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the formation mechanism of secondary minerals was discussed. XRD and SEM / EDS analysis showed that the main primary minerals left in the waste ores are pyrite, the secondary minerals are goethite, hematite, water iron ore and secondary sulfate minerals. The process of primary mineral weathered as secondary minerals starts from the defective part of the pyrite fracture zone and gradually oxidizes to the final goethite. Due to the diversity of mineral phases and morphologies in the middle process, the intermediate product may form water iron ore firstly. Because iron ores are unstable, they will be converted into goethite or hematite rapidly under different temperature and humidity conditions mine. Goethite presents a variety of morphologies during the weathering process. The acicular minerals are formed first and then recrystallized into spherical aggregates and rhombic double-cone single crystals. Finally, the surface of the waste ore is completely covered with a layer of goethite. The SEM observation of the biogenic minerals on the pyrite surface and the mycelium species on the outermost weathered layer demonstrated that the organism also played a role in the weathering of the waste ores.