Microwave-enhanced heap leaching of porphyry copper ores: Part 1 – The role of mineralogy in microwave-induced fracture networking measured by X-ray computed tomography

Giyani, B.F.; Batchelor, A.R.; Kingman, S.W.

Abstract

Previous studies have shown that the magnitude of microwave-induced fractures is dependent on ore mineralogy and texture. Those studies were based on quantitative measurements of ore competency through destructive testing or one-dimensional non-destructive ultrasonic testing, and thus did not provide detailed information about the damage (e.g., 3D fracture mapping). In this study, the role of mineralogy and texture was investigated using the X-ray Computed Tomography (X-ray CT) imaging technique to provide 3D visualization and quantification of microwave-induced fractures in four porphyry copper ores of varying lithology. The extent of mineral exposure resulting from microwave treatment was determined by comparing the Euclidean Distance Map (EDM) of pre- and post-treated scanning results, which can be used to inform leaching performance and thus select suitable ore types for microwave-assisted leaching. Ores that exhibited a greater increase in flaw thickness (up to 0.8 mm) and a higher mineral exposure (shortening the leaching pathways by up to 45 %) due to microwave treatment tended to have similar mineralogical features. The features included a high modal abundance of good microwave heaters (∼7–14 %), a coarse grain size or micro-veins of these heaters (average D50 = 300–500 µm), and contained a significant proportion of stiffer microwave heaters (e.g., pyrite) (5–11 %). Given the right mineralogy and texture, this study indicates that microwave ore pre-treatment is a potential technology that can significantly increase mineral exposure (reducing leaching pathways) by inducing macro-fractures, which can be exploited to improve metal extraction without further size reduction (e.g., in heap leaching). Alternatively, if the coarsely treated fragments are crushed, the internal mineral will be exposed due to preferential breakage along induced fracture paths, potentially promoting metal leach extraction.

Citation

Giyani, B., Batchelor, A., & Kingman, S. (2025). Microwave-enhanced heap leaching of porphyry copper ores: Part 1 – The role of mineralogy in microwave-induced fracture networking measured by X-ray computed tomography. Minerals Engineering, 233, Article 109589. https://doi.org/10.1016/j.mineng.2025.109589

• Journal Article Type: Article
• Acceptance Date: Jul 1, 2025
• Online Publication Date: Jul 9, 2025
• Publication Date: 2025-11
• Deposit Date: Jul 24, 2025
• Publicly Available Date: Jul 24, 2025
• Journal: Minerals Engineering
• Print ISSN: 0892-6875
• Electronic ISSN: 0892-6875
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 233
• Article Number: 109589
• DOI: https://doi.org/10.1016/j.mineng.2025.109589
• Keywords: Microwave, Mineralogy, Fracture, X-ray CT, Image Analysis
• Public URL: https://nottingham-repository.worktribe.com/output/51892066
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0892687525004170
• Additional Information: This article is maintained by: Elsevier; Article Title: Microwave-enhanced heap leaching of porphyry copper ores: Part 1 – The role of mineralogy in microwave-induced fracture networking measured by X-ray computed tomography; Journal Title: Minerals Engineering; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.mineng.2025.109589; Content Type: article; Copyright: © 2025 The Authors. Published by Elsevier Ltd.