Superalloys have been the primary source of rhenium demand over the past two decades, but new medical applications have the potential to disrupt the market.
Several molybdenum-rhenium (MoRe) alloy medical devices have been approved by the US Food and Administration (FDA) over the past 18 months and demand is growing fast, delegates at the Minor Metals Trade Association (MMTA) annual conference in Lisbon heard today.
China has been hoovering up much of the global supply of rhenium, which is primarily produced by Molymet in Chile, for its burgeoning aerospace manufacturing industry. China surpassed the US as the largest importer of rhenium from Chile in 2023, taking 26t — up from 2t in 2018 — according to UK-based trading firm Lipmann Walton. That was equivalent to Molymet's annual primary production. The US has historically been the largest importer for its aerospace industry, with aerospace superalloys typically accounting for around 75pc of overall rhenium demand.
But the aerospace industry will increasingly need to compete with the medical industry for supply over the coming years, several speakers said.
Mo50 Re alloy, which contains 47.5pc rhenium and 52.5pc molybdenum, has been cleared by the FDA for use in spinal implants, and more recently cardiovascular stents.
MiRus, which is developing spine, limb and structural heart disease treatments using its MoRe alloys, received FDA clearance of the first MoRe-based spine implant in 2019 and has since received further approvals for its devices.
"It takes up to 10 years for medical approvals, but now approved, the demand from this sector alone could be as much as the largest premium producer makes in any given year," Lipmann Walton managing director Suzannah Lipmann said.
Rhenium-based alloys have been associated with high-temperature applications, but they continue to find new uses at body temperature that benefit from its mechanical strength, fatigue resistance and biological performance as an alternative to traditional stainless steel, titanium, nickel-titanium and cobalt-chromium alloys used in medical implants. MoRe implants have so far not shown the allergic reactions that can results from nickel, cobalt or chromium implants.
"It's one thing to have the approval for a new design, for a new type of instrument based upon traditional materials, but it's a totally different thing to have the approval for a new material," Molymet's research director Edgardo Cisternas. "This is a major milestone that opens the door for the use of this material. It's already being used in spinal and coronary surgeries, and probably will set new standards for bio-operability."
Rhenium alloys show promise for the design of a new generation of smaller, stronger and more fatigue-resistant foot and ankle implants, which result in faster recovery and better outcomes for patients, Titan International's chief technical officer Alex Iasnikov said.
Traditional devices have a tendency to break over time, at a rate of up to 10pc, requiring replacement, Iasnikov said. But rhenium-containing implants are more robust and have shown zero breakage rates in initial testing. MoRe stents can absorb more radiation than traditional alloys, making them easier to implant more precisely and safely.
"With our ageing population around the world, this is going to result in big demand," Iasnikov said. "We believe that demand for this can grow very substantially, and I wouldn't be surprised if in 10 years it might disrupt markets."
Growing demand for rhenium, driven by megatrends such as medicine, electronics and green hydrogen refining, in addition to Chinese aerospace manufacturing, could lift prices to levels that would spur increased recycling, speakers said. This is particularly the case as annual output from the world's four major primary producers is set to remain relatively stable, given reductions in copper and molybdenum concentrate content in legacy ore bodies and a lack of new mining capacity in development.
