Recycling iridium for a greener future

After years of research, McCol Metals has developed expertise in the sustainable recovery and recycling of iridium. The company has developed an advanced process to effectively facilitate the sustainable recovery and recycling of iridium from titanium substrates – more specifically, from spent mixed metal oxide (MMO) anodes.

In the four years since its commercialization, McCol has recycled 12,000 troy ounces (oz t) of iridium oxide and counting. McCol Metals' innovative platinum group metals (PGMs) recycling process is effectively working to reduce strain on global iridium supplies during the accelerated growth of the hydrogen electrolyzer market, and beyond. Its advanced methods have positioned McCol as an internationally recognized leader in the global green economy, particularly during a time when the shift to green energy has never been more important.

Widely utilized for its high melting point and strong corrosion resistance, iridium is a rare metal that is in scarce global supply. Like other PGMs, iridium is known for its purity and unique catalytic properties.

Platinum group metals are used in an extensive range of diverse applications and industries, both existing and unexplored, ranging from the automotive sector and electric fuel cell technology, to luxury goods. In addition to its traditional uses – including in spark plugs, dip pens, and tooth fillings – iridium and iridium alloys are increasing in demand, particularly within the electrical and electrochemical sectors. Although iridium has a range of uses, worldwide demand has exceeded, and will continue to exceed, the current production rate of mined iridium; this drives the need for sustainable solutions to bridge the gap.

As global efforts actively shift toward a clean energy transition, hydrogen has emerged as a promising carbon-free fuel capable of cleaning up difficult-to-decarbonize sectors. One of the key hydrogen production technologies – proton exchange membrane (PEM) water electrolysis, also referred to PEM electrolyzers – relies on iridium as a critical input.

Within a PEM electrolyzer, iridium acts as a catalyst that drives a chemical reaction and improves overall efficacy. Of the various electrolyzers available, PEM electrolyzers are particularly suitable for clean energy applications as they pair well with variable renewable electricity resources like wind and solar. Therefore, iridium plays a pivotal role in driving the chemical reactions within PEM electrolyzers, making it essential for sustainable energy solutions.

Inevitably, as the demand for clean hydrogen increases, so does the demand for iridium. Yet, at the current rate of global production, there is not enough iridium to develop PEM electrolyzer technology at the rates necessary to match the expected growth. So, how do we move toward the inevitable green transition in our economy without straining the already struggling PGMs markets? Cue McCol Metals.

To best understand the environmental impact of McCol's process, the company commissioned Fundamental Inc. and Internat Energy Solutions Canada to conduct a cradle-to-gate life cycle assessment (LCA) back in 2022. In short, cradle-to-gate is an important term in the environmental footprint method LCA. It's an LCA model that assesses a product's environmental footprint from raw materials extraction until it leaves the factory gate.

The LCA offered a holistic environmental assessment of McCol's proprietary iridium recovery and recycling process in an effort to demonstrate its carbon footprint and environmental performance associated with the extraction and processing, transportation, and manufacturing of iridium. Results of the LCA showed that McCol's output of iridium (as iridium oxide) has a footprint of 24.5 kilograms of carbon dioxide equivalent (kg CO2e) as compared with mined and refined iridium, which has a footprint of 78,559 kg CO2e. This is a 99.97 percent reduction of greenhouse gasses.

Furthermore, given that McCol also recycles titanium plates to manufacture new anodes, its process results in a 45-fold reduction of emissions associated with the production of titanium to make the plates (per oz t of iridium). The LCA also confirmed that net negative greenhouse gas emissions – 1,094 kg CO2 eq per oz t of iridium recovered and recycled – were observed as a result of the avoided titanium primary metal production. These results highlight the significant importance and benefits of end-of-life recycling of iridium.

As climate change continues to rear its ugly head around the world, McCol Metals remains committed to pioneering the path forward in the recovery and recycling of iridium in addition to other PGMs. In a world with endless clean growth potential, creating value from waste has never been more important.

Samantha Harding is the director of marketing and communications at McCol Metals which specializes in platinum group metals recovery.

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Website: mccol.ca