title: Cross-current leaching of indium from end-of-life LCD panels.
abstract: Indium is a critical element mainly produced as a by-product of zinc mining, and it is largely used in the production process of liquid crystal display (LCD) panels. End-of-life LCDs represent a possible source of indium in the field of urban mining. In the present paper, we apply, for the first time, cross-current leaching to mobilize indium from end-of-life LCD panels. We carried out a series of treatments to leach indium. The best leaching conditions for indium were 2M sulfuric acid at 80°C for 10min, which allowed us to completely mobilize indium. Taking into account the low content of indium in end-of-life LCDs, of about 100ppm, a single step of leaching is not cost-effective. We tested 6 steps of cross-current leaching: in the first step indium leaching was complete, whereas in the second step it was in the range of 85-90%, and with 6 steps it was about 50-55%. Indium concentration in the leachate was about 35mg/L after the first step of leaching, almost 2-fold at the second step and about 3-fold at the fifth step. Then, we hypothesized to scale up the process of cross-current leaching up to 10 steps, followed by cementation with zinc to recover indium. In this simulation, the process of indium recovery was advantageous from an economic and environmental point of view. Indeed, cross-current leaching allowed to concentrate indium, save reagents, and reduce the emission of CO2 (with 10 steps we assessed that the emission of about 90kg CO2-Eq. could be avoided) thanks to the recovery of indium. This new strategy represents a useful approach for secondary production of indium from waste LCD panels.
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Rocchetti
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Amato
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Fonti
authors.affiliation: Institute of Environmental Geology and Geoengineering IGAG, National Research Council, Via Salaria km 29300, 00015 Montelibretti, Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Ubaldini
authors.affiliation: Department of Industrial Engineering, Information and Economy, University of L'Aquila, Via Giovanni Gronchi 18, 67100, Zona industriale di Pile, L'Aquila, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: De Michelis
authors.affiliation: ISL Kopacek KG, Beckmanngasse 51, 1140 Wien, Austria.
authors.forename: Bernd
authors.initials: B
authors.lastname: Kopacek
authors.affiliation: Department of Industrial Engineering, Information and Economy, University of L'Aquila, Via Giovanni Gronchi 18, 67100, Zona industriale di Pile, L'Aquila, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vegliò
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy. Electronic address: f.beolchini@univpm.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Beolchini
mesh_terms: D059029:Electronic Waste / Q000032:analysis*; D007204:Indium / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D059027:Recycling / Q000379:methods*; D012037:Refuse Disposal; D018505:Waste Management / Q000379:methods*
chemical_list: D007204:Indium
keywords: Critical raw material; Cross-current leaching; Indium; LCD panel; Urban mining