The Effect of Energy Impacts on the Acid Leaching of Eudialyte Concentrate

Abstract

ABSTRACT Using a combination of energy – dispersive X-ray spectroscopy, X-ray diffraction, X-ray fluorescence, Infrared and X-ray photoelectron spectroscopies, the effect of acids (sulfuric, hydrochloric, and nitric) and energy impacts (electrochemical, mechanochemical, high power electromagnetic pulses, ultrasound) on the leaching parameters of eudialyte concentrate was studied. Zr and Σ REE recovery after a single stage when using sulfuric acid was 91.5% and 82.4%, when using hydrochloric acid – 83.9% and 83.6%, when using nitric acid – 76.9% and 79.6%, respectively. Using sulfuric acid leads to the formation of the maximum amount of silicate gel and high loss of valuable components, while hydrochloric acid is highly aggressive to the process equipment. The possibility of nitric acid leaching intensifying by applying ultrasonic impacts was determined which disperse colloidal silicate gel, prevents the formation and precipitation of the gel on the mineral surface, provides the formation of numerous defects and microcracks on the eudialyte grains surface, including breakage thereof. Three stages of nitric acid leaching of eudialyte concentrate with an ultrasonic treatment in the first stage provide the highest recovery of zirconium (97.1%) and rare earth elements (94.5%) at a minimal loss of valuable components with silica gel. The process is recommended for commercialization.