Investigation of Different Processing Routes for Rare Earth Extraction from Discarded Tubular Lights

Discarded tubular lights were crushed and sieved to retrieve phosphor powder comprising about 40% rare earth (Y, La, Ce, Eu, Tb) present in phosphor. In this study, different processing routes comprising direct leaching, leaching followed by thermal treatment, and thermal treatment are investigated for recovery of Y, Eu, Ce, Tb, and La. The heat treatment process was optimized at different microwave exposure time and compared with the conventional heat treatment. Leaching of Eu–Y values followed by microwave treatment of leach residue with sodium hydroxide was found promising for REEs extraction. Microwave route yielded 94% La, 9% Ce, 45% Eu, and 62% Tb extraction with 50% NaOH dosage and 87% La, 8%Ce, 65% Eu, and 95% Tb extraction on increasing NaOH dosage to 100%. The material balance shows that 50 g mixed oxide of Y, Eu, and ~ 11 g mixed oxide of La, Ce, Eu, Tb, Y with purity more than 97% are recovered from 100 units of discarded tubular lights. The adopted process is simple, adaptable, and can recover appreciable rare earth elements within a short time from discarded slim tube lights.