Conceiving a high resolution and fast X-ray CT system for imaging fine multi-phase mineral particles and retrieving mineral liberation spectra

摘要

Mineral liberation studies on fine particulate systems require high resolution and fast examination of a (statistically) significant number of particles. Commercial X-ray computed tomography systems allow high resolution on very small samples (say few micrometers on single particles) and only limited resolution on large particulate samples: thus they are unsuitable for fine particle liberation studies. A computed tomography system was conceived that is capable of high resolution (say micrometric or sub-micrometric) and allows imaging at once a large number of particles. It uses a detector design with a fiber optic bundle that allows enlarging the Field of View of a standard high resolution CCD in one direction. The thin particle multi-layer in a straw offers low X-ray attenuation and permits scanning with low current and voltages that in turn allows keeping small the size of X-ray focal spot and the induced geometrical un-sharpness of the projected particles. At low magnification values (i.e., with the sample close to the detector fiber optic input end) the overall resolution is controlled by CCD pixel size and the detector allows to scan more particles. At higher magnification values the detector design allows also improvements in resolutions. The system allows studying directly in 3D those liberation problems that require micrometer-size resolution.