HYPERSPECTRAL IMAGING FOR RARE EARTH ELEMENTS OF COALS FROM NAVAJO MINE, NEW MEXICO

Rare earth elements (REEs) have become critical components in the advancement of energy technologies. Traditionally, REEs are extracted from rocks. However, recent research has expanded on identifying REE deposits in other materials like salt lakes and coal deposits worldwide. Coal seams with high REE concentrations were first discovered in East Russia two decades ago. In these coal seams, REEs are dispersed within aluminosilicates and clay minerals found in the coal and fly ash. During the process of burning coal, mineral alteration occurs. However, REEs are retained and sometimes concentrated in this process. The formation of glassy quartz and alteration of kaolinite to metakaolin in fly ash provides a suitable target for detection of REE through hyperspectral imaging in a laboratory environment. This study aims to detect REEs in coal and fly ash samples using hyperspectral imaging conducted both in laboratory and field settings. Drone and ground-based hyperspectral imaging were performed at the Navajo coal mine, and coal samples were collected during fieldwork. Additionally, a coal core was obtained to scan and identify the various layers within the coal. The spectral profiles of coal samples collected using a spectroradiometer were compared with hyperspectral images. Mineral identification within the coal samples was conducted using spectral libraries. Various clay minerals, including kaolinite, illite, and smectite, were identified as the primary targets for REE concentration in the coal samples and core. Other minerals identified included muscovite, jarosite, actinolite, and dolomite. This ongoing research demonstrates promising results in detecting the potential for REE in coal samples.