Recovering rare earths from waste phosphors using froth flotation and selective flocculation
This study explores froth flotation and selective flocculation methods to recycle waste phosphors containing several rare earth elements, namely, yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb). The effects of the presence or absence of collector and of flocculant and their dosages, as well as the pH, were investigated. Reverse flotation resulted in concentrates with grade of 27.03 percent and recovery rate of 71.36 percent, while flocculation resulted in concentrates with grade of 31.43 percent and recovery rate of 91.28 percent. The flotation and flocculation behaviors were further analyzed by X-ray diffraction analysis, zeta potential measurements, particle size distribution and other methods. The successful separation of rare earth minerals by flotation was attributed to the selective adsorption of the collector onto quartz, making it particularly recoverable by reverse flotation so as to be separated from the valuable materials. The analysis of the particle aggregation process indicated that its better flocculation performance was due to the selective adsorption of flocculants onto the unwanted materials, enlarging the flocculant sizes by forming aggregations and facilitating the separation of rare earth minerals from waste materials based on different settling rates.
Key wordsWaste phosphors Selective flocculation Froth flotation Rare earth elements
Unable to display preview. Download preview PDF.
- Hirajima, T., Bissombolo, A., Sasaki, K., Nakayama, K., Hirai, H., and Tsunekawa, M., 2005, “Floatability of rare earth phosphors from waste fluorescent lamps,” International Journal of Mineral Processing, Vol. 77, No. 4, pp. 187–198, https://doi.org/10.1016/j.minpro.2005.05.002.CrossRefGoogle Scholar
- Hirajima, T., Sasaki, K., Bissombolo, A., Hirai, H., Hamada, M., and Tsunekawa, M., 2005, “Feasibility of an efficient recovery of rare earth-activated phosphors from waste fluorescent lamps through dense-medium centrifugation,” Separation and Purification Technology, Vol. 44, No. 3, pp. 197–204, https://doi.org/10.1016/j.seppur.2004.12.014.CrossRefGoogle Scholar
- Li, H.M., 2010, “Recovery of rare earths from phosphor sludge by acid leaching,” Chinese Journal of Rare Metals, Vol. 34, No. 6, pp. 899–904.Google Scholar
- Li, R., Wu, Y., Zhang Q., and Wang, W., 2012, “Extraction of rare earth from waste three primary colors fluorescent powder in high temperature alkali fusion method,” Proceedings of CCATM 2012 International Conference, Vol. 32, pp. 795–799.Google Scholar
- Lucas, L., and Emery, R., 2006, “Assessing occupational mercury exposures during the onsite processing of spent fluorescent lamps,” Journal of Environmental Health, Vol. 68, No. 30, pp. 40–45.Google Scholar
- Mei, G.J., Rao P., and Mitsuaki, M., 2009, “Separation of red (Y2O3:Eu3+), blue (BaMgAl10O17:Eu2+) and green (CeMgAl10O17:Tb3+) rare earth phosphors by liquid/liquid extraction,” Journal of Wuhan University of Technology, Vol. 24, No. 4, pp. 603–607, https://doi.org/10.1007/s11595-009-4603-x.CrossRefGoogle Scholar
- Otsuki, A., Dodbiba, G., Shibayama, A., Sadaki, J., Mei, G.J., and Fujita, T., 2008, “Separation of rare earth fluorescent powders by two-liquid flotation using organic solvents,” Japanese Journal of Applied Physics, Vol. 47, No. 6, pp. 5093–5099, https://doi.org/10.1143/jjap.47.5093.CrossRefGoogle Scholar
- Panda, L., Baneriee, P., Biswal, S.K., Venugopal, R., and Mandre, N.R., 2013, “Performance evaluation for selectivity of the flocculant on hematite in selective flocculation,” International Journal of Mineral, Metallurgy and Materials, Vol. 20, pp. 1123–1130, https://doi.org/10.1007/s12613-013-0844-y.CrossRefGoogle Scholar
- Porob, D.G., Srivastava, A.M., Nammalwar, P.K., Ramachandran, G.C., and Comanzo, H.A., 2012, “Rare Earth Recovery from Fluorescent Material and Associated Method,” U.S. Patent 8137645, applied Aug. 25, 2011, published Mar. 20, 2012.Google Scholar
- Takahashi, T., Takano, A., and Saitoh, T., 2001, “Separation and recovery of REEs from phosphor sludge in processing plant of waste fluorescent lamp by pneumatic classification and sulfuric acidic leaching,” Selective Journal of Mining and Materials Processing Institute of Japan, Vol. 117, No. 7, pp. 579–585, https://doi.org/10.2473/shigentosozai.117.579.Google Scholar