VALORIZZAZIONE DI SCHERMI LCD A FINE VITA

The end-of-life liquid crystal displays (LCD) represent a relevant criticality for waste management since huge amounts of this waste are reaching the landfilling sites worldwide. This equipment is used in different devices (e.g., PC, Tv, notebook monitors) with an average lifespan of 6-7 years.

During the traditional recycling technology, after a first dismantling of the LCD, the resulting panel is disposed of as not-hazardous material, with a consequent loss of valuable materials. Indeed, this panel is composed of glass, the main component, and ITO, a film of Indium (90%) and tin (10%) oxides. The potential economic value of these fractions, combined with the need to decrease waste sent to landfilling sites, makes this innovative LCD recycling process essential for the development of circular economy strategy.

The identification of secondary resources of indium, defined as critical raw material by European Commission and currently extracted in Chinese mines, represents a priority. In this context, our invention shows an innovative method for the recovery of indium from LCD. The simple design includes a panel grinding followed by an acid leaching and a cementation process with Zn. The operative conditions (T 80°C, reaction time of few minutes) allow an indium recovery higher than 90% with low waste production, thanks to the exploitation of the solid residue as building material  and an efficient wastewater recirculation system.

As described in the WEEE Directive (Dir. 2012/19/UE, D. Lgs 49/2014), LCD are first dismantled to remove the hazardous components and main fractions (such as steel, aluminium, plastics) are exploited.  The end-of-life panel is currently not exploited and it represents a significant criticality for the waste management system: indeed, since a huge amount of this kind of waste is reaching the landfilling sites worldwide (around 25 million m2 of LCD per year in Europe).

On the other hand, it is estimated that the annual Indium demand will reach 25-50 ktons in the next years, to cover the future demand for both LCD and CIGS production.

Nevertheless, the mines (the main current indium resource) cannot support the further metal demand.

The need to decrease landfilled waste combined with the necessity of secondary indium production, makes the LCD recycling process crucial for the development of circular economy strategy.

The present technology addresses every SME recycler that deals with electronic waste. Its characteristics of simplicity and versality, will allow to transform a waste into a resource, directly in the premises of the recycler. The process will provide a double solution: avoiding landfilled waste and providing new Indium reserves; also creating new job positions for the LCD panel exploitation. As concerns the final Indium product, a double market option exists: either purification or use as alloy for different applications.

The unique combination of the steps described above, provides the follow advantages:

• Solid waste exploitation for building material production;
• No oxidant agent;
• No first washing step;
• No use of organic reagents;
• The short time;
• Low temperature;
• No solid waste production;
• Low wastewater production.