Recovery of Yttrium and Europium from Powder used in Fluorescent Lamps

The fluorescent powder contributes to up to 3% weight of compact fluorescent lamps, a significant portion of which contains rare earth elements such as yttrium and europium. These lamps are not recycled after usage, while they can be a good source for these elements. In this study, investigation on the process of dissolution and precipitation of yttrium and europium by hydrochloric acid and oxalic acid was targeted in order to find the optimal operating conditions. By measuring the pH changes, factors such as temperature, time, acid concentration, and solid-to-liquid ratio were determined to achieve the best leaching conditions. In addition, in the precipitation stage, the rinsing effect of yttrium hydroxide gels on increasing the purity of the product was investigated. The best leaching conditions were obtained by hydrochloric acid at 75 0C for at least 30 minutes and a solid-to-liquid ratio of 15 g/l in 0.3 M acid solution. The maximum precipitation of yttrium and europium oxalate, was obtained at pH=7. Rinsing the hydroxide gel by distilled water increased the purity of the product by more than 97% for the total of yttrium and europium, while 97% of europium and 99% of yttrium were recovered in the product.