Characterization of rare earth particles from the Florida phosphate industry through dual energy radiography and X-ray tomography.

摘要

Mineral identification is an extremely important topic in metallurgical engineering, and rare earth particle identification grows increasingly important as national and global demand increases. Due to the small concentration wherein they are usually found in the Florida phosphate industry, particle identification methods often overlook, miscount, and do not adequately describe the rare earth particles in sample streams. In this regard, dual energy radiography followed by X-ray tomography is used to quantitatively identify rare earth particles and to establish their characteristics in selected samples. It is hypothesized that by combining these two methods, better data can be gathered to make an accurate accounting of the parts per million concentration of the minerals and that time can be saved by employing both processes instead of only using X-ray tomography, which would be one procedure for mineral identification and liberation analysis. To verify that the proposed methodology does as claimed, it was used to identify rare earth particles in three sample streams provided by the Florida Industrial and Phosphate Research Institute (FIPR). Each sample was separated by size, prepared, then scanned by dual energy radiography, thresholded, and prepared and scanned by high resolution X-ray microtomography. The results were then analyzed. Based on the final digital 3D reconstruction of the samples, it was concluded that this methodology was indeed faster and more time efficient than only X-ray tomography. It was also concluded that some additional data could be gathered from the preconcentration of the X-ray tomography samples caused by preliminary dual energy radiography, but that data were dependent on the sample stream and not guaranteed for every sample scanned using this method. Therefore, it was finally concluded that the proposed methodology was time beneficial and that the potential additional data that could be gathered made this process worth exploring for future projects, especially if they involved identification of trace particles concentrated on a small, parts per million scale.