粉体精製工学部門委員会学生賞セッション

[1201-11-07] Investigation of Leaching Process of Rare Earth Elements from Various Phosphate Minerals

^○Ariuntuya Battsengel¹, Altansukh Batnasan¹, Kazutoshi Haga¹, Yasushi Watanabe¹, Atsushi Shibayama¹ (1. Akita University)

司会: 和嶋隆昌（千葉大学）

Keywords:Rare earth elements, Fluorapatite, Magnetic Separation, Leaching, Gypsum

This paper is discussed the comparison of leaching behavior of the various phosphate minerals such as apatite-based ores contain rare earth oxides ranging from 2.15% to 15.35%. Lanthanum, cerium, praseodymium and neodymium form about 95% of the total. Wet processing, using the digestion of phosphate rocks by sulfuric acid, is the most common process used to produce phosphoric acid. But it’s not favorable for rare earth containing phosphates as described in the references due to the most of rare earth elements about 70% of that contained in the feed, end up in the large amount of gypsum (CaSO₄・2H₂O) formed in the dissolution reaction. Therefore, our study aimed to find an efficient process for leaching of rare earth elements (REEs) from phosphate ores by sulphuric acid solution due to its low economic cost in recovery processes. The ore samples were subjected to a mineralogical and a chemical analysis using instruments such as XRD, SEM-EDS, XRF and ICP-OES. X-ray diffraction (XRD) analysis identified Fluorapatite (specific rare earth bearing), Quartz, Celestine, Calcite as main minerals in the ores. In order to optimize the dissolution process, effects of different parameters on the dissolution of REEs from phosphate ores were examined. To reduce impurities in the leachate, pre-removal of Fe by magnetic separation was studied as well. The results obtained from leaching experiments showed that more than 85% of rare earth elements were dissolved from apatite-based ore in diluted sulfuric acid solution.