Effects of massive electromagnetic pulses on the structural and chemical properties and leaching efficiency of eudialyte concentrate

Abstract

Scanning electron microscopy (SEM) and infrared spectroscopy (IR) were used to study the influence of high-power nanosecond electromagnetic pulses (HPEMP) and dielectric barrier discharges (DBD) in air at the atmospheric pressure on the structural and chemical properties of eudialyte. The spectral data analysis has shown that highintensity electric fields initiate mineral surface fracturing due to the weakening and/or breaking of bonds in the structural fragments of the mineral framework (presumably, Si10O27, and Si9MO30). According to the SEM data, HPEMPs cause sample surface strength reduction with the formation of new surface reliefs in the range from parallel (texp = 30 s) to polygonal fractured shapes (texp = 60 and 90 s), depending on the electromagnetic pulse exposure time texp. Eudialyte grain micromorphology after the treatment under DBD conditions is distinctively characterized by the presence of imprints of electrical current breakdown microchannels of up to 3–4 μm, with practically no microcracks or other defects occurring on the mineral surface. The intensifying effect of high-power electromagnetic pulses on the process of eudialyte concentrate acid leaching has been experimentally established. Zirconium recovery into the pregnant solution is improved by 3.4 to 4.3 % through HPEMP pretreatment and by 4.0 % through DBD exposure, with the total recovery of rare earth elements increasing by 1.1 to 1.7 %.This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation, project No. 13.1902.21.0018 (agreement No. 075-15-2020-802).