Geometallurgical Characterization of Sandstone-Hosted Vanadium Ore from the Colorado Plateau

Abstract

The La Sal District in the Four-Corners region of the United States is a major domestic resource of vanadium ore. The vanadium occurs in a variety of minerals impregnating sandstones of the Jurassic Morrison Formation. Detailed mineralogic and textural characterization of six ore samples in parallel with beaker-scale acid-leach tests provide insight into potential considerations for metallurgical recovery of vanadium from this ore type. Scanning electron microscopy (SEM) and Tescan TIMA automated mineralogy reveal substantial degree of locking of soluble vanadium-hydroxides in quartz-overgrowths and vanadium-clay particles at -850 μm grind size. Electron microprobe (EPMA) analyses of the ore mineral compositions reveal four primary vanadium hosts – montroseite, duttonite, V-illite and V-chlorite and accessory ore phases uvanite and an unidentified Ti-V hydroxide. Beaker-scale leach tests in dilute H2SO4 and NaClO3 resulted in 14 – 54% vanadium recovery. Comparison of V-illite compositions from heads and tails indicate moderate solubility of this phase – with the average composition of V-illite being reduced from an average of 16.4% V in the head analyses to 10.5% V in the tail analyses in one experiment. Through comparison of vanadium deportment in the heads and the maximum recoveries from the leach experiments it is suggested that V-chlorite is less soluble than V-illite under the study conditions.