Multisource rock characterisation at microscale for a better understanding of processing characteristics

摘要

One of the main challenges for current and future mining and processing methodologies is to understand the characteristics of the rock so that its behaviour in one or more parts of the mining process chain can be predicted. Features such as rock texture, mineralogy or border complexity between minerals control how the rock behaves from the processing plant through to the final products, including tailings disposal (Evans, Wightman, Manlapig, & Coulter, 2011; Parbhakar-Fox, Lottermoser, & Bradshaw, 2013; Yildirim, Bradshaw, Powell, Evans, & Clark, 2014) and thus can affect the feasibility of the project from technical, economic and environmental impact perspectives. Understanding how the mineralogy and texture of rock affect its behaviour in mineral processing is a demanding area of research and is essential knowledge in predicting the processability of complex ores in different stages. This study aims to demonstrate that different types of relevant information can be extracted from a range of currently available analytical methods. However, this information can be used in a complementary way for building a more comprehensive rock characterisation at the microscale and better-predicting ore processing characteristics from the intact rock through to tailing disposal. A sample of porphyry copper ore collected from a phyllic hydrothermally-altered zone was analysed with three different technologies, and the information which is relevant to processing behaviours was extracted from each of them. Firstly, thin sections were photomicrographed with a Digital Optical Microscope (DOM) to extract the borders of each mineral and the grain size of the rock. Then, the thin sections were analysed with the Mineral Liberation Analyser tool to obtain modal mineralogy, and finally, some particles from the same rock were measured using the X-ray micro-tomography system to obtain a volumetric quantification of porosity.