Recovery of Europium and Yttrium from Electronic Scrap

"The technological development observed in recent years has stimulated the application of rare earth (RE) elements. Amongst their various applications it is well worth mentioning their use in electronics, superconductors, nuclear medicine, as well as in special inks - as those used in radar invisible airplanes. TV and computer monitor screens present as coating a powder containing some rare earth elements, mainly Europium and Yttrium. The recovery of the RE elements from electronic scrap is extremely important as the economic and environmental issues are concerned. This paper describes the study of the Eu and Y recovery from e-scraps. The first step of the process was the leaching of the powder obtained by manually scraping the inside surface of the screen. After the optimization of the leaching, the dissolution of Eu and Y was higher than 98 w/t% and a pregnant sulfuric liquor containing 11.9 g L-1 Y and 0.72 g L-1 Eu was obtained. The second step was the separation of the metals found in the liquor by the solvent extraction technique. The separation of Eu and Y was carried out in a counter current circuit compound of 3 extraction stages, 7 scrubbing stages and 15 stripping stages. DEHPA was used as the extractant, whereas a diluted sulfuric acid solution was applied as scrubbing agent and a hydrochloric acid solution at high concentration was used as the stripping agent.INTRODUCTIONThe rare earths (RE) are a moderately abundant group of 17 elements composed of lanthanides, scandium and yttrium. Amongst the RE, promethium (Pm) is extremely rare, however several of the RE elements are not very rare and occur dispersed in a variety of forms (Greenwood & Earnshaw, 1984; Tyler, 2004).The innumerable applications of the RE elements are based on their particular properties, mainly their spectroscopic and magnetic properties (Martins & Isolani, 2005). The technological development observed in recent years has stimulated the application of rare earth (RE) elements. They have been used in agriculture, electronics, superconductors, nuclear medicine, automobile industry, special inks – as those used in radar invisible airplanes, X-ray screens, high intensity mercury vapour light bulbs, neutron scintilators, charged-particle detectors and optical memory reading systems (Maestro & Huguenin, 1995; Nagaosa & Binghua, 1997; Sánchez et al., 1999)."