In the platinum group metals (PGM) industry, we largely take for granted that PGMs are recyclable. Value-driven recovery and refining of these metals from their vast range of industrial applications has been quietly taking place for decades.
However, increasingly intense regulatory focus on the circularity of critical metals means we can’t rest on our laurels.
With this increasing focus will come increasing control. For materials where the market value doesn’t drive recycling and where processing standards may be lower, these controls will ensure circularity is established. But for the PGMs, that increasing control – despite not being primarily aimed at the PGMs – brings the risk of unintended consequences.
Our responsibility is to ensure we inform decision-makers about how PGM recycling works today. This will mitigate the risk of unhelpful regulations, allow learnings from the PGMs to be applied to other materials, and further boost the circularity of PGMs where the opportunity exists.
Milling and blending of PGM refinery input
The Visible ('Open') and the Invisible ('Closed') Loop
The first challenge to understanding recycling in PGMs comes from the fact that much of it is unreported.
PGM market data is published annually by Johnson Matthey and this includes figures for secondary supply, in other words the supply of recycled metal to the market each year. This is sometimes read as a figure for total recycling, which it is not, and this has led to significant underestimations of PGM recycling rates by some analysts.
Secondary supply is sourced from what we term ‘open-loop’ recycling. The loop is open because ownership of the metal is not retained by the original purchaser, so once it is recovered from the end-of-life material it can be sold on the market again. Since it affects the balance of metal in the market, it is explicitly captured in market data.
But PGMs are also routinely recycled in a ‘closed loop’, in which ownership of the metal is retained. Because the original purchaser regains the metal for reuse, the recovered metal is not available to the market and can’t be reported as market supply. But this recycling still has implications for the market because it greatly reduces the demand for ’replacement’ metal. This is particularly important for ruthenium and iridium, which are typically not recycled in open loop, but which have large amounts circulating in closed loops. This is crucial to their widespread and sustainable industrial use.
Because closed-loop recycling reduces the need for new metal, it is subtracted from reported PGM demand figures and is essentially invisible. But, and importantly, it constitutes a substantial part of the volumes handled by secondary PGM refiners such as Johnson Matthey.
DESIGN-FOR-REFINE APPROACHES ARE GAINING INCREASING TRACTION IN THE PGM INDUSTRY, SEEING RECYCLERS WORKING TOGETHER WITH OEMS AND TECHNOLOGY PROVIDERS DURING PRODUCT DEVELOPMENT TO ENSURE THAT THE PGM THEY USE TODAY WILL HAVE A KNOWN ROUTE TO RECOVERY TOMORROW.
Recycling Diversifies Supply
Recycled PGM that is returned to the market is counted as supply because primary and secondary PGM are fully fungible, with no difference in their physical properties or uses. But regulators tend to treat recycling and supply as distinct metrics, which creates complications.
The distinction routinely leads to understatement of supplies of platinum, palladium, and rhodium: today, a fifth of platinum, and a third of each of palladium and rhodium supplied to the market is recycled metal. If it is overlooked, the reliance of regions such as the EU or USA on South Africa as a PGM supplier is overestimated, resulting in PGMs being seen as a particularly high-priority target for diversification of supply.
What is missed here is that supply is already diversified, thanks to the maturity of PGM recycling coupled with the perfect fungibility of recycled and virgin PGMs. The bulk of PGM recycling infrastructure sits in the Global North, as do substantial aboveground ‘deposits’ of PGMs that can be tapped by recycling.
If true circularity in critical metals is the aim and fungibility is achieved, recycled supply must be considered. Then diversification efforts directed at trying to mine PGMs where there are none would instead be more fruitfully spent in maximising recycling returns.
Addressing Recycling Losses
Even though the value of the PGMs means that they are routinely recycled, there is still room for much improvement in recycling rates. The fact that losses in the closed loop are typically far lower than losses in the open loop provides a clue as to why this is: where suboptimal PGM recycling rates are seen today, it is overwhelmingly due to inefficient collection practices.
Technical recyclability of the PGMs is extremely high, and through the global PGM refining network the vast majority of PGMs in spent material can be recovered. With continued investment in their refining facilities by the established PGM recyclers, secondary PGM refining capacity will be sufficient and technically capable of efficiently recycling these metals from established and new uses.
So regulatory efforts to boost PGM recycling rates are best focused on increasing collection rates through mandated critical metals recovery or producer responsibility.
The potential impact of such measures is well illustrated by the example of iridium-tipped spark plugs for gasoline vehicles. Iridium is subject to tightly constrained and inelastic primary supply, as it is only mined as a minor by-product of platinum. Tens of thousands of ounces of iridium are used annually on premium spark plugs, consuming a substantial portion of the iridium mined annually, and yet today most of this iridium goes unrecovered at the end of vehicle life.
This is because the amount of iridium per plug is miniscule, and there is a fair amount of labour involved in extracting the plug from the engine and separating the iridium tip from the plug body. But if recovery of iridium from scrapped plugs were mandated, this could constitute a source of secondary iridium supply – and, moreover, one that is located within the major vehicle markets of the North.
Market supply of PGMs in 2023, with secondary supply in light blue. Closed loop recycling is not shown. For ruthenium and iridium, ‘other mining’ includes all regions outside of southern Africa.
Rev furnaces in PGM refining
Recycling as a Service
In the open loop, specialist collectors target end-of-life material to obtain PGMs that they can sell for profit. The secondary refiner can either buy this PGM from the collector or process it as a service to them. In the closed loop, secondary refining is always carried out as a service on behalf of the metal owner. This service is referred to as toll-refining and is a well-established model in the PGM industry.
It is a model that could be widely adopted in other critical metals as circularity matures because a closed loop tends to minimise collection losses. The original purchaser of the metal retains the metal and can therefore treat it as an investment rather than an expense. It locks in future availability for their business, with additional benefits for traceability of metal provenance and minimising Scope 3 emissions.
But this service can be taken one step further to build in an end-of-life solution at the very start of the life of the equipment or product. Design-for-refine approaches are gaining increasing traction in the PGM industry, seeing recyclers working together with OEMs and technology providers during product development to ensure that the PGM they use today will have a known route to recovery tomorrow.
This does not mean that technology choices need be constrained by recycling considerations. Quite often a collaboration with a specialist PGM refiner can see a ‘refine-for-design’ approach instead. If the refiner has sight of technology development that will give rise to a novel scrap material in future, it can start to develop and optimise the necessary processes to ensure this material can be recycled at high efficiency.
This has recently been exemplified by Johnson Matthey demonstrating its new HyRefine (TM) technology at lab scale, in a world-first for recycling hydrogen fuel cell and electrolyser materials and recovering both the PGMs and the valuable membrane ionomer.
Molten PGM in arc furnace
The Global Recycling Network
Recycling of PGMs is routine, but that does not mean it is easy. The technical and commercial complexity of processing these metals has led to specialist secondary PGM refiners serving the global market from large operations in centralised locations. Each PGM refiner has optimised different capabilities and typically targets different types of scrap. As a result, PGM recycling functions far more optimally and cost-effectively than it would if numerous individual companies were to undertake all the necessary processing to recycle PGMs from their variety of industrial uses within domestic boundaries.
The key exception is China, which is a closed recycling market, in that PGM-containing spent material arising in China must be recycled in China, and therefore its recycling capability is geared to serving its domestic requirement.
For the rest of the world, the salient feature of PGM recycling networks is their global nature: PGM-containing spent material and the resulting refined metal routinely cross borders. Metal that is first sold in a particular region is not necessarily used, recovered, processed, or resold in that same region, and metal can quite often be in a different region from its owner.
In PGM toll-refining, the refiners process metal on behalf of their customers and do not own the metal themselves during this process. This means that imports of PGM-containing spent material are often undertaken by the refiner of the metal, not the metal owner, and this is not typically recognised in tax and customs policy.
The experience of decades of PGM recycling shows the benefits of open borders to achieving efficient circularity. While high standards in processing must be maintained, care must be taken in setting domestic recycling targets or benchmarks so that appropriate services can still be accessed outside of domestic markets, otherwise customer choice will be reduced and the efficiency of recycling will be harmed.
Conclusion
PGM recycling works today and it works well. This circularity will be harnessed to maximise the benefit of these useful metals for the energy transition and other new applications.
What’s more, the valuable experience gained in the successful scale-up and operation of PGM recycling networks over many decades can inform more embryonic circularity in other critical materials as their own networks develop.
But to ensure robust and efficient PGM recycling networks for the future, regulatory measures should be tailored to support and optimise what already exists.
