Alessia Amato

Environmental impact assessment of different end-of-life LCD management strategies

The strong growth of the electrical and electronic equipment production combined with its short lifespan are causing the production of a significant amount of waste to treat. In particular, the present paper focuses on end-of-life liquid crystal displays (LCDs) for their significant content of valuable materials, like plastic, glass and metals that could be recovered after dismantling. In the recent literature, traditional LCD recycling processes are combined with innovative treatments, which allow to recover critical raw materials, such as indium. In this context, we have evaluated the environmental impact of four different strategies of end-of-life LCD management: the disposal in landfilling sites, the incineration, the traditional recycling treatment and an innovative process also addressed to the recovery of indium. The traditional recycling treatment resulted to be the best scenario for the environment. Indeed, a life cycle assessment study gave following environmental burdens (if negative they are credits): 18, 81, -68, -60kg CO2-equiv. and 0.08, 0.01, -0.25, -0.18mol H+-equiv., for the four scenarios in the categories of global warming and acidification, respectively. The limit of the variability of LCD composition was overcome including additional literature data in the study. In order to improve the innovative process sustainability, a system of water recirculation was optimized with a consequent impact decrease of 35% in the global warming category. Nevertheless, this action should be combined with an increase of indium concentration in the panel because the low metal content represents the bottleneck of the overall approach. In this regard, a sensitivity analysis showed that an increase of at least five times in indium concentration in the waste is needed to observe an advantage of the innovative vs the traditional recycling process, when the impact category of climate change is considered. As a whole, the life cycle assessment was confirmed as a key tool for the choice of the best option of WEEE management.

Recovery of critical metals from LCDs and Li-ion batteries

In 2014, the European Union defined a list of 20 raw materials critical for economic importance and high supply risk. The aim of this work is to present the main results achieved within the EU-FP7 Project HydroWEEE-Demo dealing with the recovery of indium and cobalt, metals included in such European list, from LCD scraps and end of life Li-ion batteries, respectively. A complete indium recovery was achieved carrying out an acidic leaching, followed by a zinc cementation. Cobalt was extracted from the electrodic powder according to the following main operations: leaching (by acid reducing conditions), primary purification (by precipitation of metal impurities), solvent extraction with D2EPHA (for the removal of metal impurities), solvent extraction with Cyanex 272 (for the separation of cobalt from nickel), cobalt recovery (by precipitation as cobalt hydroxide). Co products with 95% purity were obtained by implementation of the solvent extraction with D2EHPA and Cyanex 272.

Spent liquid crystal display panel processing by hydrometallurgical methods

Abstract Rapid technological development has caused considerable growth of the liquid crystal display (LCD) market. Considering their average lifetime of between 3 and 8 years, the management of end-of-life LCDs represents a modern critical issue. Nevertheless, this kind of waste could also represent a source of secondary raw materials, especially indium, a metal classified as a critical raw material by the European Commission, on the basis of supply risk. This element is present, in oxide form, in the indium tin oxide film, an optoelectronic material with characteristics of transparency to visible light, electric conduction, and thermal reflection. Currently, no commercial recycling processes are available but many researches have focused on the optimization of high-efficiency treatments, carried out at different conditions. This chapter aims to provide an overview of the hydrometallurgical approaches developed for indium recovery and the final valorization of end-of-life LCD.

End of life liquid crystal displays recycling: A patent review

A huge quantity of end-of-life liquid crystal displays (LCD) is collected, every year, around the world. Nowadays, this equipment is disassembled, for the removal of hazardous components (e.g. the backlight fluorescent lamps), and the resulting panel is stored. The reason is the significant content of valuable fractions (e.g. glass, metals and liquid crystals) and the lack of a recycling process, sustainable from an economic and an environmental point of view. Considering the relevance of this critical issue, the scientific community focused on the development of different recovery strategies, summarized in several available reviews. Nevertheless, the literature has not yet dealt with the technological innovation aspect. With the aim of filling this gap, the present review presents the international patents about LCD recycling, from 1999 to 2017, using the Espacenet platform, that has access to all the most relevant patent databases worldwide. The inventions include a first waste disassembling, followed by the classification of the target fractions and the recovery of metal (e.g. indium, indium tin oxide) and non-metal (e.g. glass, polarizing film, liquid crystal) components.

SUPPLY AND SUBSTITUTION OPTIONS FOR SELECTED CRITICAL RAW MATERIALS: COBALT, NIOBIUM, TUNGSTEN, YTTRIUM AND RARE EARTHS ELEMENTS

European industry is dependent on the import of raw materials. The European Commission has recognized that some raw materials are crucial for the function of the European economy and show a high risk of supply shortage. This communication addresses supply and substitution options for selected critical raw materials: cobalt, niobium, tungsten, yttrium, and the rare earth elements. For each element, the most relevant data concerning mining, abundance, recycling rates and possible substitutes are summarized and discussed.​