IMF : INSTITUTE OF MATERIALS FINISHING
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 highperformance 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 photonic 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 controlled
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 .
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8 NOVEMBER 2020 twitter : @ surfaceworldmag