A truly circular process for recycling all main raw materials of waste of LCDs screens of smartphones

Paper ID: 
Published under CEST2023
Proceedings ISBN:
Proceedings ISSN: 2944-9820
Martelo L., Silva M., Bacelo H., Bastos M., (Corresponding) Soares H.
A liquid-crystal display (LCD) screen is composed by two transparent glasses coated with indium-tin oxide (ITO) on it and crystal liquids (LCs) sandwiched between them. The current implemented recycling process usually adopts mechanical crushing or pyrolysis as the primary LCDs screens treatment step. However, the toxic (LCs) and valuable recyclable (Indium, In) materials are treated together and the In recovery rate is low. Furthermore, in a circular economy perspective, the recovery of glass and plastics from the LCD screens should be targeted too, to close the loop of the recycling chain. Here, we propose a hybrid (physical plus chemical steps) method that removes the polymeric film (PF) attached to the ITO glass to recover the highest amount of In and also to recover the plastic fraction and the glass substrate. For that, the cut LCDs pieces were put in a water and ethyl acetate (1:5) mixture in a low-pressure reactor (1 hour at 180 ÂșC) for detaching the PF, separate it and dissolve the LCs in the solvent. Subsequently, a high In recovery yield (99.0%) was achieved from the ITO glass under microwave-assisted soft acid leaching conditions followed by continuous column ion-exchange technology (IET) to purify In from other metals impurities
: Indium, Critical Raw Material, LCD screens recycling