title: A hydrometallurgical process for the recovery of terbium from fluorescent lamps: Experimental design, optimization of acid leaching process and process analysis.
abstract: Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (42). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths.
authors: Department of Industrial Engineering and Information and Economy, University of L'Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100, L'Aquila, Italy.
authors: Valentina
authors: V
authors: Innocenzi
authors: Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy. Electronic address: nicolomaria.ippolito@uniroma1.it.
authors: Nicolò Maria
authors: NM
authors: Ippolito
authors: Department of Industrial Engineering and Information and Economy, University of L'Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100, L'Aquila, Italy.
authors: Ida
authors: I
authors: De Michelis
authors: Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, via Eudossiana 18, Rome 00184, Italy.
authors: Franco
authors: F
authors: Medici
authors: Department of Industrial Engineering and Information and Economy, University of L'Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100, L'Aquila, Italy.
authors: Francesco
authors: F
authors: Vegliò
mesh_terms: D002563:Cerium / Q000032:analysis / Q000737:chemistry; D005063:Europium / Q000032:analysis / Q000737:chemistry; D006794:Household Articles; D006851:Hydrochloric Acid / Q000737:chemistry*; D007811:Lanthanum / Q000032:analysis / Q000737:chemistry; D008029:Lighting; D010087:Oxides / Q000032:analysis / Q000737:chemistry; D059027:Recycling / Q000379:methods*; D012107:Research Design; D013725:Terbium / Q000032:analysis / Q000737:chemistry*; D015019:Yttrium / Q000032:analysis / Q000737:chemistry
chemical_list: D010087:Oxides; D013725:Terbium; D002563:Cerium; D005063:Europium; C103829:lanthanum oxide; D015019:Yttrium; C030583:ceric oxide; D007811:Lanthanum; D006851:Hydrochloric Acid; C091417:yttria
keywords: Hazardous materials; Hydrometallurgical process; Rare earth elements; Spent fluorescent lamps; Terbium