Three-dimensional X-Ray computed tomographic characterization of micro-imperfections in ground siderite particles, C. Zhang, L.X. Li, X. Zhang, N. Li, H.M. Zheng, Z.T. Yuan , and X.M. Wang

In metal mines, comminution is commonly used to liberate minerals for subsequent mineral concentration processes, such as flotation, magnetic separation and gravity separation. However, ores are aggregates of valuable minerals and their disseminated gangue minerals, and these minerals exhibit diverse comminution behaviours. In carbonate-bearing iron ores, hematite, siderite, and quartz are the predominant minerals, of which hematite is the objective recoverable mineral. In this regard, the present study aimed to identify the imperfections in siderite minerals by X-ray computed tomography (XCT), and thus quantitatively characterise their size and shape in terms of Feret diameter and aspect ratio, as well as other parameters. XCT images indicated the protogenetic ubiquity of pores <5 μm in diameter and cracks of 7-8 μm inside siderite particles. In the ground product of artificially mixed siderite and hematite, siderite particles were smaller than hematite particles. Siderite particles had a larger surface area and greater surface roughness than hematite particles of the same volume, which was attributable to the intrinsic holes and cracks in siderite particles. This study provides an insight into the relationship between the inherent imperfections of minerals and their comminution properties. Keywords: Siderite; X-ray computed tomography; particle imperfections; grinding behaviour; sliming