PGMs find new planet-saving role for clean energy transition Critical Minerals Alliances 2023 - September 12, 2023
After 50 years of scrubbing the emissions from fossil-fueled transportation and industry, platinum group metals are finding new roles as catalysts for the transition to a low-carbon energy future.
"Platinum group metals (PGM) are critical for today's energy sector industrial base and will play a key role in tomorrow's decarbonized economy," U.S. Department of Energy inked in an informational brochure on these transitional metals, also known as platinum group elements.
PGMs – platinum, palladium, rhodium, ruthenium, iridium, and osmium – have a long list of attributes that make them indispensable to global industries. These characteristics include exceptionally high resistance to wear, tarnishing, and chemical attack; the ability to endure high temperatures; and excellent electrical stability. It is the catalytic properties of this group of metals, however, that scrubbed the exhausts from fossil-fueled energy of the 20th century and are being used to create cleaner fuels for the low-carbon energy future that lies ahead.
"Catalysts based on PGMs are used in a variety of applications such as chemical manufacturing, automotive catalytic converters, and petroleum refining," DOE wrote. "They are also central to emerging decarbonization technologies such as water electrolyzers for green hydrogen production and fuel cells for vehicles and stationary energy storage."
While the blue-collar job of scrubbing harmful emissions from automobile tailpipes and industrial smokestacks has been the primary use for PGMs, these metals are just as comfortable in a lab coat or at a black-tie event.
"PGMs are also used in catalysts for bulk-chemical production and petroleum refining; dental and medical devices; electronic applications, such as in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors; glass manufacturing; investment; jewelry; and laboratory equipment," the U.S. Geological Survey penned in its Mineral Commodity Summaries 2023 report.
Three PGMs in particular – platinum, palladium, and rhodium – are minted into coins and bars for investment purposes, solidifying the group's role as precious metals.
The rarity and beauty of jewelry donned at a black-tie soiree, combined with hardworking durability and catalytic characteristics featured on Mike Rowe's "Dirty Jobs," elevates the criticality of this group of elements.
As fossil fuel-burning cars give way to electric mobility, so goes the need for catalytic converters. The same catalytic properties used to scrub the exhaust from ICE vehicles, however, are being used to convert water into green hydrogen fuel.
DOE is particularly interested in the production of green hydrogen to decarbonize steelmaking and other industrial processes in the U.S., which account for 23% of the nation's greenhouse gas emissions.
"To meet the nation's goal of net-zero carbon emissions by 2050, decarbonization of these energy and emissions intensive processes will be crucial. PGM catalysts, and the green hydrogen produced with them, can enable dramatic emissions reductions in these hard-to-decarbonize industrial sectors," the Energy Department wrote.
Fuel cells being manufactured for large trucks, busses, trains, ships, and even airplanes also take advantage of the PGM's catalytic properties to split hydrogen molecules into electrons that create a flow of electricity and protons that unite with oxygen to produce water vapor exhaust and heat.
The platinum metals, however, are very rare and roughly 98% of the world's known reserves are found in South Africa (90%) and Russia (8%).
"The six PGMs are among the least abundant elements on earth and occur in only a few countries worldwide, with the majority of production and reserves in South Africa and Russia," DOE wrote. "To secure the supply chains for these clean energy technologies, as well as green hydrogen and chemical manufacturing, the United States needs to invest in its domestic resources and in innovations in PGM substitutions, material efficiency, and recycling."
The combination of scarcity, import reliance, and importance to clean energy and other industrial sectors plants PGMs on critical minerals lists compiled by both USGS and DOE.
After considering the entire suite of PGMs as one commodity on its original 2019 critical minerals list, USGS evaluated each of these metals separately when updating the list in 2022.
The 2022 list names five PGMs – iridium, platinum, palladium, rhodium, and ruthenium – as critical to the U.S.
IRIDIUM – The rarest of the PGMs, iridium sells for more than $4,500/oz. This most expensive PGM is known for its chemical and thermal stability. Iridium is the anode catalyst for hydrogen production. Like rhodium, iridium is also used as a hardening agent for platinum. This biologically compatible PGM also has medical applications.
PALLADIUM – With the unique ability to absorb hydrogen, palladium is used in chemical processes that require hydrogen exchange, such as those used to produce raw materials for synthetic rubber and nylon. Palladium also has excellent catalytic properties and is often used as a substitute for platinum but, at roughly $1,300/oz, is more expensive.
PLATINUM – This PGM namesake, prized as a precious and industrial metal, sells for around $900 per ounce. In addition to its primary use as a catalyst for scrubbing emissions and hydrogen fuel technologies, platinum is used for computer hard drives, fiber optics, LCDs, spark plugs, pacemakers, and dental fillings.
RHODIUM – Rhodium is a silver–colored metal that is extremely resistant to corrosion and highly reflective – qualities used to add luster to jewelry, mirrors, and searchlights. Rhodium is also used to harden and improve the corrosion resistance of platinum and palladium alloys. Due to its uses and rarity, rhodium sells for more than $3,000/oz.
RUTHENIUM – Ruthenium is very hard and also a good alloying agent for platinum and palladium. Due to its conductive properties and durability, this PGM is used in wear-resistant electrical contacts for computers and smartphones. Ruthenium, which is also used in highly efficient solar cells and as a catalyst, sells for under $500/oz.
Based on its analysis of forward-leaning energy technologies, DOE has included two PGMs – iridium and platinum – on its list of critical materials.
Due to its importance to the energy transition and high supply risks, iridium ranks particularly high on the U.S. Energy Department's list of critical materials.
This is largely due to iridium being the catalyst of choice for the anodes of the proton electrolyte membrane (PEM) electrolyzers that produce green hydrogen from water. This extremely scarce PGM's ability to endure the acidic conditions that occur during this process makes the catalyst worth its weight in iridium.
"Iridium is one of the rarest elements in the earth's crust," DOE wrote. "A particular challenge to the supply of iridium in coming years is the expected decline in demand for co-products palladium and rhodium used in internal combustion vehicles' catalytic converters and palladium used in diesel engine vehicles' catalytic converters. The majority of iridium is produced from mines and refiners in South Africa and Zimbabwe where mine operations have been affected by environmental, operational, safety, and labor issues."
Despite the high price of iridium, it is almost never found in concentrations that would support its recovery independent of the other platinum metals.
"It is unlikely that iridium would be produced as a primary product, although some iridium may be recovered from platinum mine overburden, discarded ores, and tailings," DOE penned in its 2023 Critical Materials Assessment published in July.
While the Stillwater and East Boulder mines, about 85 miles southwest of Billings, Montana, produced roughly $880 million of PGMs during 2022, iridium is not among the platinum metals recovered. This makes the U.S. 100% dependent on imports for this critical rare metal.
For these reasons, iridium is high on the Energy Department's list of materials critical to America's low-carbon emissions future.
While the criticality of platinum is not as high as iridium, DOE considers the namesake PGM as near-critical in the short term and rising into the critical category during the 2025-2035 medium span considered in the Critical Materials Assessment.
"Platinum demand for catalytic converters is expected to decline after 2025 as vehicle technologies transition to battery and fuel cell-powered vehicles (FCEVs)," DOE penned in the report. "This decline may be mitigated as PEM fuel cells and electrolyzers are adopted as important technologies for the hydrogen economy."
In the short term, the Energy Department foresees an excess supply of platinum as the auto sector will need less for catalytic converters as it phases out ICE vehicles in favor of EVs. The rise in hydrogen fuel technologies and fuel cell-powered transportation is expected to create new demand that outpaces supply in the medium term considered in DOE's Critical Minerals Assessment.
"The supply risk for platinum is significant in the short and long term," DOE wrote.
During 2022, the U.S. was dependent on imports for 66% of its platinum needs.
Both Canada, the fourth largest producer of PGMs, and the U.S., the fifth largest, have highly prospective areas for bolstering the production of this group of critical catalyst metals.
Canadian mines produced 699,000 troy ounces of PGMs in 2021.
Roughly 73% of Canada's platinum metals are mined in Ontario, which is home to Impala Canada's Lac des Iles Mine, the only primary PGM mine in the country. The balance of the Ontario PGMs is produced as a byproduct of nickel mining in the Sudbury region, where global miner Vale has five mines, a mill, and a smelter.
There are two advanced exploration projects in northern Ontario that are focused on PGMs as the primary commodities.
When it comes to the clean energy transition, it is fortuitous that PGMs are found alongside the nickel needed for EV and renewable energy storage batteries, and the Canadian PGMs not produced in Ontario are recovered as a byproduct of mining the battery metals in Quebec, Manitoba, Newfoundland and Labrador.
Besides the PGM-rich regions of Montana and Ontario, along with the platinum metals being produced as byproducts of nickel mining in Canada, there are some areas of North America prospective for future sources of this group of high-priced critical metals.
A special category of PGM-hosting deposits that partially derive their name from Alaska – Ural-Alaska-type ultramafic complexes – hint at the prospectivity for this group of industrious precious metals across the Last Frontier.
Wrangellia – a geological terrane that arcs more than 1,250 miles across the breadth of Alaska, through southern Yukon, and down the western side of British Columbia – is highly prospective for these ultramafic deposits enriched with nickel, copper, cobalt, platinum, palladium, iridium, rhodium, osmium, ruthenium, gold, and silver.
The most advanced PGM deposit along this massive geological terrane is Nickel Shäw in southeastern Yukon, about 60 miles east of the Alaska border.
According to a 2018 calculation, Nickel Shäw hosts 323.4 million metric tons of measured and indicated resources averaging 0.26 g/t (2.65 million oz) palladium, 0.2 g/t (2.63 million oz) platinum, 0.27% (1.88 billion lb) nickel, 0.16% (1.11 billion lb) copper, and 0.015% (107 million lb) cobalt.
Nickel Creek Platinum Corp. is exploring 11 high-priority targets that could add to this resource as it continues to optimize plans for developing a mine at Nickel Shäw.
There are intriguing signs that similar PGM-nickel-copper-cobalt deposits may be found in the Alaska portion of Wrangellia, such as the Nikolai property about 250 miles northwest of Nickel Shäw.
Discovered by INCO in the 1990s, the Nikolai project hosts a roughly 10-mile-long trend of lower-grade nickel-copper-cobalt-chromium-PGE mineralization.
Alaska Energy Metals Corp., which recently acquired this property, is carrying out drilling in 2023 to establish a resource at this bulk tonnage target known as Eureka and is exploring much higher-grade targets on the adjacent Canwell property.
One particularly high-grade rock collected from this Alaska property contained 13.6% nickel, 2.9% copper, and 26 g/t PGMs.
"Located in the USA, we intend to help North America transition to electrical power for vehicles and other rechargeable battery powered products," said Alaska Energy Metals President and CEO Gregory Beischer.