Hafnium – hot right now because it can take the heat
Demand for the minor metal hafnium has stepped up with growing use within the aerospace industry for heat-resistant alloys, while nuclear cutbacks have reduced available Hafnium supply.
About 15 years ago, just before the MMTA Dinner, my staff asked me what metal they should mention if anyone happened to ask what we traded. As I was worried about losing what little business we had by careless talk, I suggested the team said “hafnium”.
“Just say to anyone who asks: ‘We do hafnium’,” I said.
The dinner was on a Thursday and at that time we did not do hafnium. But the young people did as they were asked. By Monday we had enquiries both to buy and sell hafnium; and by the end of that week we were trading it and have been doing so ever since. However, if anyone reading this has ideas of warehousing large amounts of money in this small market, please turn away. At prices of about $1,000 per kg, this 50 tonnes a year market is worth no more than $50 million.
But on such delicate markets, much hangs. In this particular case, some nickel-cobalt base complex alloys for aerospace and industrial gas turbines in a range of directionally solidified castings. It is a group of alloys that counts hafnium as un-substitutable.
The main alloy of choice is MAR M 247, containing 1.5% of hafnium, developed in the 1970s and patented by US company Martin Marietta Corp for use in the hot part of jet engines – the shrouds, vanes and blades (mainly the low pressure turbine). As operating temperatures have gone up, so has the demand for these alloys, and therefore for hafnium.
The trouble is… The trouble about getting hold of hafnium, though, is that like a number of by-product elements, those who need it are not necessarily the priority for those who make it.
Although the metal was first separated in 1923, the main usage of hafnium, and hence the main driver for its recovery, did not arrive until the birth of the nuclear industry, post-war.
In fuel assemblies, hafnium-free zirconium is required. Zirconium is a “low neutron absorber”, meaning it is blind (transparent) to neutrons. Hafnium does the opposite – it blocks neutrons. In nuclear plant and equipment, zirconium is used in tubes and sheet to allow the neutrons to pass safely through the assembly wall to stimulate the uranium granules as part of the nuclear reaction.
The bottom line is that, while the aerospace and IGT industries have become a useful outlet for by-product hafnium, the nuclear-focused people who generate it will always put their industry first.
The second problem is how hafnium arises in nature. It is only found in any recoverable quantity with zircon sand – at an average rate of 1:50 versus zirconium – and the majority of zirconia is sold to the refractory industry for furnace bricks or liners. For this use there is no need to remove the hafnium and the consequence is that the hafnium is lost.
So why is hafnium hot right now?
There are two factors tugging at hafnium today.
On the supply side, the March 2011 tsunami that knocked out Fukushima made a great big hole in nuclear plans all round the world and stopped the nuclear renaissance in its tracks.
All Japan’s 48 reactors were closed and Germany announced that all of its would be closed by 2022.
Less nuclear-grade zirconium was needed, so less de-hafniation occurred with the result that hafnium output declined.
Quest for higher operating temperatures
Meantime, aerospace continues its quest for higher operating temperatures. While a group of rhenium-bearing, nickel-base alloys (such as CMSX-4, PW-1484 and their derivatives) allow blades to withstand the highest temperatures of all (with environments now creeping towards 2000°C in some cases) it follows that other parts, once made from lower temperature alloys, must be upgraded too.
MAR M 247 has been the great beneficiary of this demand. It is now thought that at least 40 tonnes of hafnium crystal bars are needed just for MAR M 247 production. And that is before all the other uses for hafnium – in plasma cutting tips, Intel Pentium ® chips, as well as its original application in control rods to block neutrons.
Today, the market is a virtual duopoly made up of Areva of France and ATI Wah Chang in the USA. There were others – but Russia no longer exports hafnium, Ukraine no longer produces it and Western Zirconium does not process the by-product hafnium to metal. That said, China would like to be involved but has not yet developed the plant for reliable de-hafniation.
It is thought that Areva produces about 18 tpy of hafnium crystal bars and ATI Wah Chang about the same – but their outputs are inelastic.
Growing aerospace demand, seen in record aircraft deliveries in 2014 (Airbus: 629; Boeing: 723), explains where some of the demand is coming from.
Undoubtedly, this additional take-up should have an effect on prices which, if the analogous market of rhenium is anything to go by, could be a few multiples higher than the present level of $1,000 per kg.
For me, it is just another example, if any more were needed, of the disconnect between the industry that generates an important but minor element, and those most in need of it. In defence of my own industry – trading – it also highlights the value of its role. In the case of hafnium, merchants may be the only source left for consumers to turn to.
Anthony Lipmann Published in Metal Bulletin on Jan 19th 2015