Characterization of LCD Screens for Recovery of Strategic Metals: In and TR (Rare Earths)
Abstract
Electronic scrap has grown exponentially in the last decade, representing a serious ecological issue. Additionally, some components, such as liquid crystal displays (LCDs), contain strategic elements, such as rare earths (TR), whose depletion and scarce reserves oblige the search for alternatives to increase the availability of these elements. This work presents the preparation and characterization of a representative sample from electronic scrap LCD screens, such as televisions, electronic tablets, laptops and cell phones. Chemical and physical methods were employed to determine the presence of technologically interesting metals. The particle size of the LCD screens was reduced by mechanical grinding and separated using screens with different mesh sizes: +60, -60 + 120, -120 + 200, -200 + 270, 270 + 325 and -325. The ground material was analyzed by X-ray diffraction and fluorescence (DRX, FRX, respectively) and by scanning electron microscopy (SEM). Subsequently, each different particle size powder was digested with aqua regia (HCl: HNO3, 3: 1) and the liquors obtained were analyzed by ICP to quantify the metallic content. The highest values of 2,425 and 580 mg/kg for In and TR (Pr, Er and Gd), respectively, were found in the smallest (-325 mesh) size fraction, which are economically interesting to recover.
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References
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