Application of microwave imaging in sensor-based ore sorting

Ore sorting is a pre-concentration technique used in mineral processing to reject low-grade ore particles from the feed material at coarse particle sizes. Modern ore sorting technology employs sensors to distinguish between the properties of different rocks. This study aims to investigate if microwave imaging (MWI) can be used to distinguish rocks that contain valuable minerals or metals from those that do not, for potential application in sensor-based ore sorting as a new sensing method. Compared to more established sensors, such as XRT and XRF, MWI has the potential to penetrate deeper into ore particles and to be used as a supplementary method for analyzing those ores with high contrast in electromagnetic (EM) properties between valuable minerals/metals and gangue minerals. Microwave scattering simulations and experimental measurements are performed on both gold ore cores and gold ore particles with irregular shapes. A MWI algorithm and a sorting algorithm are proposed to form images of rocks and to make the accept/reject sorting decision, respectively. Both simulation and measurement results suggest the feasibility of using MWI to identify the presence of valuable minerals or metals in ores.