Indium Recovery from ITO in LCD Glass Using Magnetic Separation and Sulfuric Acid: Influence of Fractions and Process Conditions

This study emphasizes the role of magnetic separation as a novel pretreatment strategy for the recovery of indium from ITO coatings in LCD screen glass. Previous studies have primarily focused on the magnetic separation of leaching residues. In this work, a reverse approach is proposed, and for the first time, magnetic separation was systematically applied prior to leaching. Our results demonstrate that indium accumulates in the ferromagnetic fraction, indicating its association with Fe-rich phases. In addition to Fe, the behavior of Sr and Si was also evaluated, providing a broader understanding of elemental distribution within LCD glass. This finding offers new insights into the distribution and mobility of indium during hydrometallurgical processing and highlights magnetic separation as a valuable step for improving recovery efficiency. To establish optimal leaching conditions, preliminary experiments were performed on ground LCD glass using sulfuric acid at three concentrations (0.1, 1, and 5 M) and two temperatures (21 °C and 65 °C) for both coarse (>1 mm) and fine (<1 mm) particle fractions. All residues and solid-state analyses were performed using the XRF method. Acid molarity was found to be the dominant factor controlling indium dissolution, with 5 M H2SO4 selected as the most effective leaching medium. Statistical evaluation further clarified the dissolution trends of these elements and confirmed the significance of magnetic separation in enhancing the efficiency of indium recovery.