Solubilization of Rare Earth Elements (La, Ce, and Tb) in Waste Phosphor Using Concentrated Sulfuric Acid

Abstract

In the present study, extraction of rare earth elements (La, Ce, and Tb) in phosphor using concentrated sulfuric acid followed by water extraction was investigated in order to develop a recycling process of waste phosphor containing rare earth elements (La, Ce, and Tb). As a pretreatment, Y and Eu were leached with 2.0 mol/dm³ sulfuric acid solution. More than 80% of La, Ce, and Tb were extracted with H₂O after heating at 120°C in concentrated sulfuric acid. Extraction efficiencies of La, Ce, and Tb increased with the heating temperature, heating time, and amount of sulfuric acid. A solution containing 5.45 g/dm³ La, 2.57 g/dm³ Ce, and 1.43 g/dm³ Tb was obtained under the condition of 3.00 g sample, 4.00 g sulfuric acid, 120°C heating temperature, 4hrs heating time, and 100 cm³ H₂O for extraction.