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International audience; In this report, indium-tin-oxide (ITO)-layer extraction from end-of-life (EOL) Liquid Crystal Displays (LCDs) was discussed by sulfuric acid leaching with simultaneous application of ultrasonication on the ITO-side of glass/ITO panels, exhibiting various dimensions. Applying this technique presents several advantages compared to the traditional leaching process such as fast and controllable kinetics, high extraction yield of indium and tin, selective recovery of these two metals possible, and the opportunity to recycle the neat glass separately avoiding additional separation processes. ITO-dissolution kinetics from EOL LCD panels were investigated as function of leaching time and acidity of sulfuric acid. At a temperature of 60°C, a nearly quantitative indium yield was obtained using an acid concentration of 18 mol/L by simultaneous application of ultrasonication, whereas only 70 % were recovered in the absence of ultrasound. Results from ICP-AES agreed well with SEM/BSE observations demonstrating the high efficiency of the ultrasound assisted process since only 3-4 min were required to obtain maximum ITO recovery.

In recent years, the amount of Waste Electrical and Electronic Equipment (WEEE), such as TVs and Liquid Crystal Displays (LCDs), is constantly increasing. These devices consume non-renewable and therefore limited natural resources, and generate waste that can be a source of pollution. LCDs from WEEE contain highly recyclable Secondary Raw Material (SRM), including liquid crystals and indium-tin oxide (ITO). At present, there are few industrial processes for the recovery of this material for the purpose of recovery. The main objective of this thesis is to translate the results obtained at the UMET laboratory scale into an industrial process developed by Envie 2e Nord. This process allows ultrasonic-assisted chemical extraction of liquid crystals and ITO from LCD screens without glass crushing and regardless of screen size. In order to ensure their quality, the materials obtained have been characterized using various efficient analysis techniques: ICP-OES, SEM/EDS-BSE, ToF-SIMS, POM, FTIR, DSC, TGA,.... Part of the work involved prospecting for recovery routes, particularly for treated liquid crystals.; Ces dernières années, la quantité des Déchets d’Equipements Electriques et Electroniques (DEEE), tels les téléviseurs et moniteurs à cristaux liquides (LCD pour Liquid Crystal Display), est en constante augmentation. Ces dispositifs sont consommateurs de ressources naturelles non renouvelables et donc limitées, et génèrent des déchets pouvant être source de pollution. Ces DEEE contiennent de la Matière Première Secondaire (MPS) recyclable de grand intérêt, notamment les cristaux liquides et l’oxyde d’indium-étain (ITO). A l’heure actuelle, il existe peu de procédés industriels permettant la récupération de cette matière dans le but d’une valorisation. Cette thèse a pour objectif principal la transposition des résultats obtenus à l’échelle du laboratoire UMET sur un procédé industriel développé par l’entreprise Envie 2e Nord. Ce procédé permet l’extraction chimique assistée par ultrasons des cristaux liquides et de l’ITO des écrans LCD sans broyage de verre et quelles que soient les dimensions de l’écran. Afin de s’assurer de leur qualité, les matériaux obtenus ont été caractérisés à l’aide de différentes techniques d’analyse performantes : ICP-OES, MEB/EDS-BSE, ToF-SIMS, MOP, IRTF, DSC, ATG,.... Une partie du travail a concerné la prospection de voies de valorisation, notamment pour les cristaux liquides traités.