tailieunhanh - Preliminary study on separation of rare earth metals from leach solution of discarded fluorescent powder by solvent extraction

The best separation circuit included four-stage counter current extraction for yttrium separation with 20 %v/v PC88A in kerosene (O/A = 1/1, room temperature, 20 min of contact, pH of ) and stripping step with 3 M HCl acid (O/A = 1/1, room temperature, 30 min of contact). | Vietnam Journal of Science and Technology 56 (2C) (2018) 133-139 PRELIMINARY STUDY ON SEPARATION OF RARE EARTH METALS FROM LEACH SOLUTION OF DISCARDED FLUORESCENT POWDER BY SOLVENT EXTRACTION Nguyen Duc Quang, Ha Vinh Hung*, Vu Minh Trang, Le Huy Viet, Huynh Trung Hai School of Environmental Science and Technology, Hanoi University of Science and Technology, 1 Dai Co Viet, Ha Noi * Email: Received: 20 May 2018; Accepted for publication: 22 August 2018 ABSTRACT Discarded fluorescent lamps were considered as hazardous waste in Vietnam (code is 160106). However, its composition contained valuable rare earth metals, which can be recycled and recovered by leaching and solvent extraction processes. The present study sought to define the conditions of separation for rare earth elementals (REEs) from acid leach solution by solvent extraction using PC88A. The acid leach solution was obtained from leaching of fluorescent powder. Efficiencies on REEs extractions as functions of pH levels, extractant concentration, O/A ratio, metal concentration were investigated. For pH values greater than and less than , the orders of the yields extraction were determined: yttrium > terbium > europium > aluminum and calcium. The best separation circuit included four-stage counter current extraction for yttrium separation with 20 %v/v PC88A in kerosene (O/A = 1/1, room temperature, 20 min of contact, pH of ) and stripping step with 3 M HCl acid (O/A = 1/1, room temperature, 30 min of contact). After yttrium separation, the leach solution was extracted at pH of in the same other conditions with two-stage counter current extraction to recover terbium and europium group. The final recovery from leach liquor was higher than 98 % and the grade of the final product was % (for yttrium) and % (for terbium and europium group). Keywords: rare earth, recovery, fluorescent lamp, solvent extraction, PC88A. 1. INTRODUCTION Legally, the discarded .