Catalytic converter theft - what's behind it?Copyright: © Peter Winandy
It is a worldwide phenomenon: Catalytic converters are stolen from vehicles because of the precious metals they contain, such as palladium, platinum, and rhodium. We asked Professor Elisabeth Clausen of the Chair and Institute of Advanced Mining Technologies about what is behind these thefts.
Professor Clausen, what makes these raw materials so valuable?
Platinum (Pt), palladium (Pd), and rhodium (Rh) – as well as ruthenium (Ru), osmium (Os), and iridium (Ir) – belong to the so-called platinum group metals (PGM). They are extremely valuable due to their special properties and use in many essential products, making them economically very important. At the same time, there is a significant risk of supply chain uncertainty. This is why the EU currently classifies platinum group metals and other raw materials such as tungsten, tantalum, rare earths, and coking coal as critical raw materials.
Where and how are these precious metals mined?
The platinum group metals occur in different types of deposits, primarily along with nickel and copper. We can distinguish between two different types: PGM-dominated deposits with low contents of base metal sulfides and nickel-copper-dominated deposits in which the PGMs are extracted as by-products. The raw materials are won using both deep and open-pit mining methods.
The so-called Bushveld Complex in South Africa is the world's most important deposit of PGM-dominated ores. For nickel-copper deposits, the two largest deposits are located in Canada and the Russian Federation. The world's top two producing countries are South Africa and the Russian Federation, which accounted for nearly 83 percent of global production in 2020. In addition to primary production, however, secondary production is also an important source of supply globally. In 2020, about 100 tons of palladium and platinum were recovered from new and old scrap metal worldwide. In comparison, primary production in 2020 was around 365 tons. In the case of secondary raw materials, however, it is important to note that, at most, only the quantity that was originally used at some point can be recovered. The service life of products or different recycling rates must also be taken into account.
You mentioned the high economic importance of these raw materials earlier. Where exactly do we encounter them in everyday life?
Platinum (Pt), palladium (Pd), and rhodium (Rh) are primarily used for the production of automotive exhaust catalysts and industrial catalysts. That is why catalytic converters are still valuable even when the cars have reached the end of their lives. The jewelry industry is another important buyer of platinum. In addition, PGMs are used in emerging technologies, such as fuel cells, solar cells, medical technology, and special capacitors or seawater desalination plants. Other areas of application include the glass industry, medical and dental technology, and metrology.