Identification of Surface Processes in Individual Minerals of a Complex Ore through the Analysis of Polished Sections Using Polarization Microscopy and X-ray Photoelectron Spectroscopy (XPS)
Identification of Surface Processes in Individual Minerals of a Complex Ore through the Analysis of Polished Sections Using Polarization Microscopy and X-ray Photoelectron Spectroscopy (XPS)
复制标题
通过使用偏光显微镜和 X 射线光电子能谱 (XPS) 分析抛光切片来识别复杂矿石中单个矿物的表面过程
作者：
D. Silva;Chuan He;Melissa Jacome;C. Benndorf;A. Teplyakov;J. Rodriguez
了解矿石加工过程中矿物的变化对于制定旨在提高金属提取效率的战略至关重要。由于矿石在成分、矿物学和结构方面的可变性，这项任务往往很困难。特别是，表面过程，如金属再吸附（preg-robbing）在特定的矿物是难以评估的，即使他们可能是重要的，因为再吸附的材料可以阻塞有价值的矿物和负面影响的提取过程。在这里，我们展示了一种简单而强大的方法，通过这种方法，通过结合偏光显微镜（MP）和X射线光电子能谱（XPS）来识别单个矿物的表面过程。以秘鲁中部安第斯山脉的某含银多金属硫化矿（黄铁矿为主，含少量方铅矿）为例，跟踪了氰化过程中样品的变化。虽然偏光显微镜是鉴定矿物种类的工具，XPS提供了铅在黄铁矿表面上的再吸附的证据，可能是氧化铅/氢氧化物。黄铁矿的表面并没有表现出显着的变化后，浸出过程中根据微观结果，虽然形式的氧化铁检测与再吸附的铅通过XPS。方铅矿，嵌入在黄铁矿中，溶解在氰化物浸出过程中，所证明的PM和XPS信号的减少与硫化物和硫酸盐的位置。同时，在不同位置处的铅峰的上升证实了再吸附的铅物质不能是硫化物或硫酸盐。有趣的是，铅没有检测到铜蓝表面在浸出过程中，这表明，铅的再吸附是一个过程，取决于矿物的性质，这里所示的方法是一个工具，了解复杂的表面过程中影响各种矿物金属提取过程中的重要性。
Understanding the changes of a mineral during ore processing is of capital importance for the development of strategies aimed at increasing the efficiency of metal extraction. This task is often difficult due to the variability of the ore in terms of composition, mineralogy and texture. In particular, surface processes such as metal re-adsorption (preg-robbing) on specific minerals are difficult to evaluate, even though they may be of importance as the re-adsorbed material can be blocking the valuable mineral and negatively affect the extraction process. Here, we show a simple yet powerful approach, through which surface processes in individual minerals are identified by combining polarization microscopy (MP) and X-ray photoelectron spectroscopy (XPS). Taking as an example a silver-containing polymetallic sulfide ore from the Peruvian central Andes (pyrite-based with small amounts of galena), we track the changes in the sample during the course of cyanidation. While polarization microscopy is instrumental for identifying mineralogical species, XPS provides evidence of the re-adsorption of lead on a pyrite surface, possibly as lead oxide/hydroxide. The surface of pyrite does not show significant changes after the leaching process according to the microscopic results, although forms of oxidized iron are detected together with the re-adsorption of lead by XPS. Galena, embedded in pyrite, dissolves during cyanide leaching, as evidenced by PM and by the decrease of XPS signals at the positions associated with sulfide and sulfate. At the same time, the rise of a lead peak at a different position confirms that the re-adsorbed lead species cannot be sulfides or sulfates. Interestingly, lead is not detected on covellite surfaces during leaching, which shows that lead re-adsorption is a process that depends on the nature of the mineral. The methodology shown here is a tool of significant importance for understanding complex surface processes affecting various minerals during metal extraction.