Modern manufacturing and process engineering use an ever-increasing number of critical elements, including rare earths (RE) and precious metals. The volume of RE in everyday products is estimated to be growing at around 10%/year.
The biggest RE consumer product is the car. The average electrically-powered automobile engine contains something like 35 of them – including neodymium, praseodymium and dysprosium. In addition, the sensors to measure and control oxygen content in burning the fuel (lean/rich mixture) use yttrium. Three-way catalytic converters and the polishes of windshields and mirrors contain cerium.
In hybrid vehicles, the Ni-metal-hydride battery contains lanthanum while the magnets on electric traction motors use neodymium and dysprosium. As for derived products, gasoline has for many years used fluid cracking catalysts (FCCs) containing lanthanum, cerium and mixed RE ores.
Just how critical RE are to economies worldwide and the global consumer society became obvious in 2010 when China, which enjoys almost monopolistic status as a producer and reserves holder, imposed strict export quotas claiming it was attempting to reduce pollution and protect resources.
China’s stance sent prices of these prized commodities – critical to the manufacturing processes of leading multi-nationals such as General Electric (wind turbines), Toyota and Nissan (hybrid and electric cars) and Blackberry and Apple (smartphones and tablet computers) –rocketing by hundreds of percent.
The ensuing geopolitical fall-out saw the US, EU and Japan protest to the World Trade Organization (WTO). They argued that China was effectively putting a squeeze on world supplies and the export restrictions gave Chinese companies an unfair competitive edge.
Defending its position, China, affirmed that limits on exports of RE, as well as the metals tungsten and molybdenum, were needed to prevent over-mining. In March 2014, the WTO ruled that China’s export duties, quotas, and quota administration breached its rules; China has appealed.
Upward price pressure on RE had already relented considerably in anticipation of a WTO ruling against China. However, Ryan Castilloux, founder of Adamas Intelligence, which specialises in the provision of market intelligence in critical sectors of the mining and metals industry, underlined that two driving factors have sent most RE prices rising again since the start of 2014, neither of which relate to the WTO ruling.
‘The first has been a significant increase in RE exports out of China over the first five months of this year versus 2013,’ he says. ‘And the second is speculation that the Chinese government would purchase a significant volume of rare earths from its domestic producers for strategic stockpiling.’
But he warns against generalising as some other commercially important RE-containing compounds, notably cerium oxide, lanthanum oxide and yttrium oxide, have ‘trended continuously lower’.
While RE have captured the headlines, they are only one aspect of the endangered elements debate. In late May 2014, the EU published its European Critical Raw Materials Review, a list of 20 elements and materials deemed to be critical to Europe’s manufacturing industry but which are subject to supply risk. They include antimony, niobium, magnesium, natural graphite, magnesite, tungsten, germanium, indium, gallium, fluorspar, silicon, cobalt, platinum group metals, borate phosphate rock, beryllium and coking coal as well as heavy and light RE.
The EU’s ‘critical’ list totaled 14 elements and materials as recently as 2010.
Speaking at the American Chemical Society’s (ACS) annual Green Chemistry and Sustainability conference in June 2014, Rod Eggert, of the Colorado School of Mines, in a paper entitled Endangered Elements: Critical Materials in the Supply Chain, picked up on the theme of ‘a Periodic Table under siege’.
He highlighted the smartphone, which contains between 60 and 70 elements. ‘Most of the Periodic Table is in a smartphone and in doing so we are calling upon elements, which up to now have been used in very small quantities and specialised applications, if they’ve ever been used at all in materials. And drawing on ever-increasing portions of the Periodic Table has led to issues related to availability.’
General Electric, meanwhile, ‘uses something like 73 of the first 80 elements in the Periodic Table in its products or in processes used to make its products,’ he pointed out. ‘So what’s true for the cell phone is also true for General Electric and the manufacturing economy as a whole.’
Supplies of critical materials may be fragile or insecure for a number of reasons, with geographically-concentrated production perhaps the most prominent medium-term risk, Eggert argued. ‘As a consequence, there’s the prospect of high or volatile prices, physical unavailability or all three, raising the concern that the supply chain risks threatening the development of materials we would otherwise like to deploy.’
Nevertheless, his take-away message was: ‘we’re not running out – there are no examples of elements, which are moving towards exhaustion or extinction over the next century.’ The issues, he said, are developing technologies capable of extracting materials, the environmental and social consequences of extraction and use, as well the economics of extracting elements and developing materials at costs that people are willing and able to pay for.
Paul Chirik of the department of chemistry at Princeton University, US, also spoke at the meeting and gave an insight into his team’s work to replace the established precious metal catalysts with more abundant and environmentally-compatible base metals, such as manganese, iron and cobalt. The thrust of his message was to show how chemical catalysis ‘actually uses a lot of these rare and exotic elements to make items that are much more common and much more simple and much less sophisticated than a smartphone’.
Chirik focused on common household products that rely on platinum group metals such as rhodium and platinum for their manufacture. Silicone release coatings, for example, used for adhesives on envelopes and labels as well as kitchen utensils, are made by using a platinum catalyst that is very hard if not impossible to recover because it is used in such a low concentration.
It turns out that about a third of the cost of these coatings is due to the residual platinium used in their manufacture. ‘So this is a great example of a case where you would like to find a catalyst based on a terrifically abundant element,’ Chirik said.
Chirik’s group has reported iron catalysts (Science, doi:10.1126/science.1214451) that operate with higher activity and selectivity than current platinum catalysts. ‘These are yet to be used commercially but are currently undergoing evaluation and optimisation,’ he says.
Heightened supply risks relating to strategic elements led to the US setting up the Critical Materials Institute (CMI), which opened for business in June 2013. ‘We focus on the three pillars of the US Department of Energy’s Critical Materials Strategy: diversification of sources; development of alternatives; and better use of what is currently available through more efficient manufacturing and improved recycling,’ said CMI’s director, Alex King.
CMI co-operates with a group of industrial ‘member and affiliate’ companies whose activities span the supply chain from mining to complete systems manufacturing and recycling.
‘The industrial interface is extremely important to CMI, since all of our work has to be focused on possible commercial use,’ King says, adding that CMI is constantly reviewing its ‘agenda’ as demand for materials shifts in response to supply issues.
CMI focuses on elements that include neodymium and dysprosium, essential for lightweight, high-strength permanent magnets used in wind-turbine generators and hybrid vehicle motors, as well as other technologies such as hard disk drives, small motors and loudspeakers; europium, terbium and yttrium, used in efficient light sources such as fluorescent lamps, LED lamps, flat panel displays and lithium (lightweight rechargeable batteries) and tellurium (solar cell technologies).
Yet another element in the spotlight at the ACS conference was iridium, pointed out Avtar Matharu, deputy director of the Green Chemistry Centre of Excellence at the University of York, UK. ‘Liquid crystal display (LCD) screens or the flat panel industry have a huge, huge use for indium tin oxide and other markets are coming onstream – for example, photovoltaics,’ Matharu said.
On the ‘Substitutability Index’ for endangered elements, which runs on a scale from 0 to 1, with 0 being almost like a drop-in replacement and 1 being extremely difficult to find a substitute, he noted that ‘indium sits at 0.82 on the Index so this puts the challenge of finding a substitute for indium into perspective’.
Matharu also touched on the recovery and recycling of the numerous critical materials found in electronic goods. ‘If we are going to tap into the urban mine of the future, we really need engineers who can produce goods that are sort of smart disassembly so at end of life we can actually get at these critical metals and materials easily.’
Stuart Todd is a freelance writer based in France