The Platinum Group Metals (PGMs) are made up platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru) and osmium (Os). These metals are desirable in the marketplace due to their value to the industrial, electronic, medical, and especially now, the automotive markets. The PGMs have been in the news lately because one of the leading domestic uses for these elements is in catalytic converters (which decrease harmful emissions from automobiles) and theft of these parts as skyrocketed.
We have written several times over the past few years about the issue of catalytic converters being stolen and sold to scrap metal recycling companies for hundreds of dollars in cash for each converter. The auto part is coated with chemicals and a combination of platinum group metals (PGMs). The recyclers extract the precious metals and resell them. Unfortunately, the beginning of 2021 has seen a substantial uptick in these thefts. Several US cities are reporting 50, 100, even 300 catalytic converter thefts in just a few months’ time.
While theft is a concern for products already manufactured, obtaining new PGMs is just as problematic. Mining these valuable minerals is fraught with difficulty. Mineable PGM deposits are very rare and much less productive than those containing many common metals.
A 2017 USGS Publication* explains why PGEs are among the rarest metals…
Earth’s upper crust contains only about 0.0005 part per million (ppm) platinum. Today, the average grade of PGEs in ores that are mined primarily for their PGE concentrations varies from 5 to 15 ppm, although the concentration of PGEs in hand-picked ore specimens may range from tens to hundreds of parts per million.
More than 100 different minerals have one of the PGEs as an essential component. PGE minerals occur as native metals. They also occur as compounds with other transition metals (copper, iron, mercury, nickel, and silver), post-transition metals (bismuth, lead, and tin), metalloids (antimony, arsenic, and tellurium), and nonmetals (selenium and sulfur).
The latest USGS report notes that world resources of PGMs are estimated to total more than 100 million kilograms. The largest reserves are in the Bushveld Complex in South Africa. United States yearly mine production of the platinum group elements has increased from 13,000 kilograms in 2016 to 14,000 kilograms in 2020 for palladium; the same period showed a smaller increase from 3,890 to 4,000 for platinum. As reported, “production of PGMs in South Africa, the world’s leading supplier of mined material, decreased by 11% compared with that of 2019 owing to temporary lockdowns related to the COVID-19 pandemic as well as increased labor costs, increased costs for electricity, an unreliable supply of electricity, and challenges related to deep-level mining.”
Handheld XRF analyzers can help meet the platinum group metals challenge. These instruments can identify alloys, detect tramp elements, and analyze precious metals, so they are valuable to metal recycling scrap yards. But these instruments also help meet the mining challenge, because they also deliver geochemical data.
In some instances – such as grade control of concentrates, and exploration of rich zones – precious metals, including some PGMs, can be detected directly using handheld x-ray fluorescence (XRF) analyzers. In other occurrences – where very low concentrations of these metals are under exploration – pathfinder elements can be used successfully as exploration tools to locate potential zones.
The pathfinder elements, along with precious metals, are enriched in anomalous areas and are easily detected compared to the target elements. Analysis of PGE pathfinder elements using handheld XRF analyzers is emerging as a valuable tool in precious metal exploration operations.
Handheld XRF analyzers can help deliver rapid sample analysis and reliable data that enables mining companies to increase their discovery success rates and target the highest quality deposits of PGMs. Unfortunately, there’s nothing they can do about stopping the theft of them.
*Reference: Zientek, M.L., Loferski, P.J., Parks, H.L., Schulte, R.F., and Seal, R.R., II, 2017, Platinum-group elements, chap. N of Schulz, K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply: U.S. Geological Survey Professional Paper 1802, p. N1–N91, https://doi.org/10.3133/pp1802N.