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Precious Materials Recovery from Electronic Waste
Short-lived electronic devices have become a significant waste stream globally. A common electronic waste is the liquid crystal display (LCD) screen used in electronic devices such as mobile phones, televisions and computers. Currently, these devices are disassembled in order to eliminate any dangerous parts (e.g., backlight systems containing mercury) and the LCD panel is disposed as non-hazardous waste. Only a small portion of the disassembled components are currently recycled and large amounts of this waste are still being landfilled or incinerated.
The electronic waste, especially LCD panels are a potential source of valuable materials, such as glass and rare metals. LCDs contain two glass plates sandwiching a liquid-crystal mixture. The outer plate surface is covered with polarizer films, and the inner plate surface comprises a functional indium tin oxide (ITO) film composed of indium oxide (90%) and tin oxide (10%). Indium is a critical raw material for industry with limited supplies and high cost. Existing solutions to recover precious materials from LCD panel involves the use of extreme conditions of time and temperature, as well as strong oxidizing agents to eliminate the organic and the need for downstream treatment of the high chemical oxygen demand (COD) wastewater.
Given the above, the technology owner has developed an energy- and water-efficient recycling process to recover high-purity Indium and glass from shredded LCD panel powder (<1 mm), while avoiding the use of strong oxidizing agent or organic chemicals. The process uses a sulphuric acid-based leaching solution to extract Indium in multiple leaching steps, followed sodium hydroxide and zinc powder cementation treatments to further improve its purity. The glass-rich solid residue may be separated and used as a construction material, and the solution may be recirculated for subsequent leaching steps.
This process enables overall material extraction efficiency of more than 90% and may be used in existing electronic waste recycling facilities. The technology owner is seeking industry or research partners to license the technology and co-develop/extend the recycling technology to enable the recycling of photovoltaic panels such as thin film solar panel made of copper indium gallium selenide (CIGS) cells, as well as smartphone screens.
Technology Features, Specifications and Advantages
- Comprehensive LCD panel recycling process, starting from the initial shredding to the recovery steps of Indium and glass.
- Simple mechanical-based process design and mild leaching reaction temperature of 80°C, using recirculated water (up to 85%) for the reactions that is free of free of oxidising agents or organic chemicals.
- Solid waste exploitation for building material production from the extracted glass material.
- Short processing time (<1 hour), low wastewater production and does not generate solid waste.
- Electronic waste recyclers
- Industries: electrical and electronics, transports, medical devices, etc.
- Applications: end-of-life LCD screen treatment, material recovery facilities, rare metals recovery.
- Indium is mainly used for LCD production and its use will grow for photovoltaic panel CIGS (Copper, Indium, Gallium, Selenite) manufacturing. The annual Indium demand is around 62 ton/year and 5 ton/year in Europe and Italy, respectively. The average amount of the discarded LCD is around 57 kton/year and 6 kton/year in EU and Italy, respectively. Therefore, the possible exploitation of the whole LCD amount could cover the 20% of the annual Indium demand.
- The potential economic value of the recovered metal 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 process allows provides a double solution: avoiding landfilled waste whilst providing new Indium reserves, plus the final Indium product can be further purified or use as an alloy for different applications.