Increasing demand for rare earth elements (REEs) and instabilities in their supply chain requires an alternative source for REEs. Discarded tubular lights have been evaluated in this study as a potential source of REEs. Phosphor dust separated after crushing, and sieving of tubular lights, comprises approximately 34% rare earths (Y, Eu, Ce, Tb) in Y1.90Eu0.10O3 and Al11Ce0.67MgO19Tb0.33 phases. The present study is focused on a two-step recovery of REEs, the recovery of Y and Eu (> 95%) via a leaching route followed by the recovery of Ce (40%) and Tb (> 95%) from leach residue using microwave exposure followed by leaching. The Y and Eu leaching process is optimized using a statistical design to evaluate different leaching parameters, reaction kinetics, while the activation energy was also studied. The leach residue was microwave-treated with NaOH for the dissociation of Ce- and Tb-bearing phases. The material balance reveals that it is possible to recover 52 g of the mixed oxides of Y and Eu and 7 g of the mixed oxides of Tb, Ce, Eu, and Y with purities of over 99% from 100 units of tubular lights.
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The authors would like to acknowledge the funding received from the Indian Institute of Technology, Roorkee (Faculty Initiation Grant; FIG-100714).