The recovery of Gallium from WEEE
The recovery of gallium from WEEE (ReGall)A consortium of six UK companies has been awarded funding by Innovate UK for a nine month project to study the opportunities for recovering pure gallium metal from LED lights obtained from Waste Electrical and Electronic Equipment (WEEE)..
UK Team to be world leaders in studying the recovery of gallium from WEEE
A consortium of six UK companies has been awarded funding by Innovate UK for a nine months project to study the opportunities for recovering pure gallium metal from LED lights obtained from Waste Electrical and Electronic Equipment (WEEE). The gallium found in LEDs is in the form of gallium nitride (GaN), which is a high-performance semiconductor and a vital component in LEDs. The project started on 1st November 2020 and will be the first time that gallium will be recovered from End-of-Life components. Currently, gallium is only recovered from material offcuts and shavings.
The commercially focussed consortium comprises: S2S – a circular economy specialist SME with expertise in IT asset recovery and WEEE recycling; Envaqua Research Ltd – a company devoted to the development and implementation of resource recovery technologies; E. C. Williams Ltd – another SME that specialises in electroplating and surface finishing; Recolight – a not-for-profit company that operates over 2,000 collection points in the UK for the collection of waste lamps; HSSMI – a company specialising in advancing innovative manufacturing techniques; and the Institute of Materials Finishing – a charitable organisation that focuses on surface coatings, engineering and related technologies, as well as providing educational courses for the sector.
Gallium nitride is used in an ever-increasing range of applications which currently include lasers and pho- tonic applications (LEDs etc), solar cells, RF (Radio Frequency) power amplifiers, wireless chargers for phones, heart pumps, etc. and light detection systems in autonomous cars. Gallium is also used as a cost -effective substitute for crystalline silicon and in high temperature thermometers and barometers due to its unique property of having the widest liquid element temperature range of any known element, with the liquid phase spreading between 29.8 °C to 2,204 °C. It is widely thought that, as the demand and use of electric vehicles rises, there will be a corresponding increase in demand for gallium, which will also be used in PEMD (Power, Electronics and Machine Drives). Hence, gallium and its compounds will play an increasingly important role in our futures.
LEDs have been known for over a century and the first one was a crystal of silicon carbide (SiC), but it was not until the early 1960s that a visible light LED was developed. These LEDs use materials including gallium arsenide (GaAs), gallium phosphide (GaP) and gallium arsenide phosphide (GaAsP) to make the light- producing process more efficient. LEDs also have carefully con- trolled amounts of indium or aluminium added, and they can also be doped with other elements such as magnesium. These dopants result in the generation of coloured LEDs – notably, red, orange, yellow and green. LEDs emitting blue light are based on silicon carbide and gallium nitride. The colour and intensity of an LED depends on the combination of materials used and the energy gaps of the positive (p) and negative (n) materials used in the diode. An important part of the project will be to separate out these dopant metals to ensure a high purity output of metallic gallium.
Gallium is not considered to be a precious metal element, but it does command a relatively high value of about £2,500/tonne, (although this does fluctuate). It is classified as a Critical Raw Material by the EU, with the largest producers of gallium being China (80%), followed by Germany (8%) and the Ukraine (5%).
Gallium is found naturally in bauxite (an aluminium ore), which provides over 95% of gallium extraction and in sulfidic zinc ores, as well as some coals. It is usually only found naturally in very low concentrations of less than 50 ppm; this makes it uneconomic to extract as a primary product, but it is recovered from the processing of bauxite to make aluminium and from zinc ores used for zinc production, so its availability is directly linked to demand for other metals. However, where extraction has been considered, it has required the use of highly corrosive and hazardous materials.
To mitigate the use of hazardous extractive processes, this study plans to demonstrate that the more benign Deep Eutectic Solvents (DES), or “Ionic Liquids”, will be able to deliver a cost-effective method for recovering high quality gallium metal from the mixture of materials found in LED lights. The consortium is very aware of the challenges it faces but is very confident of success.