Energy Effects on Structural and Chemical Transformations of Base Minerals of Eudialyte Concentrate in Nitric Acid Leach
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MINERAL DRESSING
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Energy Effects on Structural and Chemical Transformations of Base Minerals of Eudialyte Concentrate in Nitric Acid Leaching V. A. Chanturiaa, E. V. Koporulinaa*, V. G. Minenkoa, and A. L. Samuseva a
Academician Melnikov Research Institute for Comprehensive Exploitation of Mineral Resources—IPKON, Russian Academy of Sciences, Moscow, 111020 Russia *e-mail: [email protected] Received May 17, 2019 Revised May 17, 2019 Accepted July 3, 2019 Abstract—Using the methods of X-ray phase analysis, analytical scanning electron microscopy and inductively coupled plasma mass spectrometry, the influence of preliminary energy effects on transformations of eudialyte concentrate base minerals during nitric acid leaching, their micromorphology and phase composition of the surface is studied. It is found that preliminary mechanical activation of the concentrate provides a 34–45% increase in the recovery of zirconium and the sum of rare-earth metal oxides into pregnant solution. Electrochemical processing of mineral suspension during nitric acid leaching and, to a greater extent, ultrasound effects contribute to an additional increase in the recovery of these elements into pregnant solution by 12–23% due to the cleaning of mineral grain surface from amorphous phases and formation of structural inhomogeneities. Keywords: Nitric acid leaching, eudialyte concentrate, morphology, phase composition, zirconium, rare-earth metals, mechanical activation, energy effects. DOI: 10.1134/S1062739119045989
INTRODUCTION
Eudialyte ores of the Lovozero deposit in the Murmansk Region are the promising source for zirconium and rare earth metal production in Russia. In [1−11], pyro- and hydrometallurgical options for the processing of eudialyte concentrates based on multi-stage decomposition by acids and alkalis are proposed. The main problems of hydrometallurgical processing of eudialyte are associated with the presence of a significant amount of silicon (40–60%) in the composition. During acid leaching, silicon passes into solution in the form of silicic acid, which undergoes polycondensation with the formation of polymers of various composition and structure up to stable gels, which leads to a decrease in the recovery of valuable components, deteriorates filtration performance, and complicates further processing of solutions by recovery and sorption methods. Methods for solving the problem of processing high-silicon ores by hydrometallurgical methods are preliminary mechanical activation and energy effects. High efficiency of nitric acid leaching of eudialyte concentrate using ultrasound effects was substantiated and confirmed in [12, 13]. The effect of various grinding machines on acid leaching of eu
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