Optimization of Yttrium oxide leaching from red phosphor waste fluorescent lamps by D-optimal design

Rare earth metals have been widely used as raw materials for luminescent materials, vehicle catalysts, cathode ray tubes and permanent magnet motors. In this work, leaching of yttrium oxide from waste red fluorescent lamp by sulfuric acid was investigated. For this purpose, several waste lamps were broken under ventilator and powder was separated from glassy material. Then, the powder was collected by brushing. The effects of various parameters on leaching process were explored and the optimal conditions were determined as stirring speed of 800 rpm, temperature of 90C, H2SO4 concentration of M, leaching time of 2h and S/L ratio of 20% w/v. In this condition the yields of yttrium and europium solution were 98% and 92%, respectively. The analysis of variance showed that time and temperature have significant positive effect on yttrium solution in sulfuric acid medium.

Keywords:

red fluorescent lamps , leaching , yttrium oxide , europium