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Gallium is becoming an increasingly widespread material for semiconductors in electronic applications. To limit the need for new resources, the ReGaIL project explored and proved that it is possible to create a circular system by recovering gallium from end-of-life LED (light-emitting diode) lamps in a novel, environmentally friendly way. The recovered gallium can then find a second life in other use cases, amongst them as a key element in semiconductors for power electronics, machines, and drives (PEMD).
Moreover, the project demonstrated new recovery methods using novel solutions, such as ionic liquids, instead of the more conventional aqueous chemistries based on strong oxidants and concentrated acids. This article explains how gallium, as well as other metals, such as indium, silver, and gold, can be recovered from LED lamps and what costs need to be considered by businesses looking to gain profit from gallium recycling.
The current market price of gallium is £210 per kilogram, but this is expected to rise as gallium is increasingly being used as a semiconductor in various electronic applications. Adding to this the opportunity to extract other metals, such as indium, silver, and gold from the LEDs, in a similar process, would significantly increase the profit margin. Although an LED lamp holds a relatively small amount of gallium (about 0.025g per LED) and other metals, the increasing value of these metals means that a solution that maximises volume while minimising costs could be quite profitable.
The gallium recycling process has four distinct stages – collection and sorting; dismantling and comminution (where the gallium is reduced to smaller particles); dissolution; and electroplating – each of which incurs specific costs. HSSMI detailed these stages, analysing the costs and waste streams in each stage, as they can have a significant impact on the costliness of the entire process. As a robust process for recovering gallium from LED lamps is still being developed, quantitative economic values cannot be accurately estimated, but the types of costs and, conversely, drivers for profitability involved can still be identified.
There are costs that are common to all four stages of the gallium recovery process, such as the cost of purchase, maintenance and running of the site and buildings of a presumed recovery facility or multiple facilities, the labour costs, as well as the cost of transportation of the material between each step of the process. These could potentially be minimised by carrying out the entire process on one site or by combining some of the steps into one facility.
Collection & Sorting of LED Lamps
There are four main costs associated with this step of the process: the capital investment into collection containers, transportation containers, supply availability, and treatment costs. The costs associated with collection and transportation can be limited by using standardised containers and decreasing the number of trips to gather the collection containers. Once collected, the LED lamps are transported to an approved authorised treatment facility (AATF), as they may be mixed with lamps that contain mercury and therefore require specialised handling. Depending on the length of the journey between the collection sites and the AATF, the geographical location of the AATF may have a significant impact on transportation costs.
The supply availability – that is, the sheer volume of lamps to be collected – may impact the investment necessary for collection and transportation containers, as the supply will determine the number of containers, vehicles, and journeys necessary. It is worth keeping in mind that the proportion of LED lamps is expected to increase in the future, causing an increase in the transportation cost following lamp separation. However, the overall process is likely to become more efficient as the yield of LED lamps collected increases.
The treatment costs include expenses related to the manual labour of sorting the collected lamps. This may include PPE (personal protective equipment) for staff due to the presence of hazardous chemicals, as well as investments in conveyor lines, lifting equipment, and bins. However, further work needs to be carried out to analyse this in detail, as there may be an opportunity to automate the treatment process partially or entirely.
Dismantling & Comminution
The most critical aspect that needs to be considered with this part of the process is the choice between manual and automated dismantling of the LEDs. Manual dismantling will have high labour costs but smaller capital costs, and the automated process will be the opposite. As it takes 5 to 10 minutes to remove the LED chip from a lamp, thus generating an estimated £2.50 labour cost per lamp, which is higher than the average inherent value of gallium obtained from the lamp, it becomes economically unfeasible to have the dismantling done manually.
Further analysis should be done in this area to identify the most optimal equipment – granulator and ball mill – to use for dismantling the LED lamps. For reference, the cost of this equipment in similar recycling processes is around £120,000 for a granulator and £75,000 for a ball mill.
At this stage, the ionic liquid is required to separate the gallium. Ionic liquids are a more environmentally friendly alternative to the conventional aqueous chemistries that are based on strong oxidants and concentrated acids. At roughly £300 per litre, the ionic liquid is one of the most expensive elements in the entire gallium recovery process. One litre of ionic liquid can dissolve approximately 7g of gallium, so the expense incurred will depend on batch size. Given the high upfront cost, it is important to note that most of the ionic liquid can be regenerated in the recovery process and recycled, meaning that the purchase of the ionic liquid is a one-time investment, although it will have to be periodically topped up.
Additional capital investment will be necessary for a filtration or centrifuge system to remove the slurry of ionic liquid left behind after the recovery process. This will help minimise the ionic liquid losses. The cost of a small chemical reactor, which is where the dissolution takes place, also needs to be factored in.
After being dissolved by the ionic liquid, the recovered gallium goes through an electroplating process, which takes place in a batch reactor – another significant capital cost. There is also the cost of the copper cathode used to electroplate the gallium onto. It is as of yet unclear whether it might be possible to reuse the copper cathode after the removal of the gallium. This stage will require further operating costs related to the chemical consumables used for cleaning and treating the cathode, the electricity and heating of the electroplating process, as well as air filters and electricity costs incurred during fume extraction.
Once the gallium has been deposited onto the cathode, the final separation takes place – the gallium is removed from the cathode and separated from the other deposited metals. Further separation and purification will be necessary to ensure a high purity level of the gallium. This will require further expenditure on processing equipment.
Limiting the waste produced in the recovery process helps reduce overall costs, as well as environmental impact.
The main waste streams identified in the recycling process are:
– Glass, plastic and metal from the remainder of the LED lamp after the LED boards are removed to be comminuted. If these cannot be easily separated, they will be sent for Waste from Electrical and Electronic Equipment (WEEE) recycling.
– The slurry of ionic liquid left behind after gallium, and potentially other metals, are dissolved in it. This waste can either be consigned to generic disposal or an alternative route, such as using it as a filler in a cement matrix.
– The contaminated water from rinsing the cathode after electroplating. Care needs to be taken to dispose of the waters safely.
– The cathode, depending on whether or not it can be reused.
Overall, the analysis has shown that waste is minimal throughout the entire process and materials are being reused or recycled wherever possible.
This article explained the novel, environmentally friendly process for gallium recovery that was proved in the ReGaIL project. Although it is technically possible to recover gallium, more work needs to be carried out to establish how this can be done in a cost-effective way to bring profit. Moreover, it is not yet clear how much gallium this process would yield, making it impossible to forecast the overall revenue. This requires further research on the development and scale up of the gallium recovery process. Nonetheless, with gallium becoming ever more popular as a component of semiconductors, as well as the rise of automotive electrification, it is anticipated that the price of gallium will rise accordingly, creating an incentive for recycling businesses to pursue gallium recovery. ReGaIL has taken the first steps by proving that gallium recovery is possible, and the consortium hopes that other projects will build upon these findings.
Find out more about our work on gallium recovery in this case study, which presents the simulation that HSSMI built to explore and refine the gallium recovery process within a recovery facility.
ReGaIL (Recovery of Gallium from Ionic Liquids) was a collaborative project between eight partners – S2S Group, Recolight, Institute of Materials Finishing, Envaqua Research, E.C. Williams, and HSSMI – and conducted with funding from Innovate UK. For more information about the gallium recovery process, please contact the project team by writing to HSSMI’s Circular Economy Manager Savina Venkova at email@example.com.