150 years ago, Dimitri Mendeleev developed the Periodic Table of the Elements. A way of organising all the information about the behaviour of the 63 elements known at the time. It has become an iconic image of science, and in celebration 2019 has been named the International Year of the Periodic Table.
Many people had tried to make sense of the messy collection of rules and examples that was chemistry. This was critical to the developing industrial revolution. We knew about elements, materials that cannot be broken down into anything simpler by heat, acid, solvent or electricity. We knew that elements could combine to make more complex structures, from rocks to pigments to the building blocks of life. But there was no logic that explained what we saw; no framework.
Mendeleev worked obsessively on the patterns he found, carrying around a deck of cards of elements and their properties that he constantly dealt out in different arrangements like a scientific game of Patience or Solitaire. One story tells that exhausted from efforts to find the pattern on a three-day train journey he fell asleep and saw the solution in a dream.
The genius of Mendeleev’s table is that he recognised that to make the patterns work he needed to leave gaps for elements that had not yet been discovered and predicted their atomic weights and chemical properties. Gallium, germanium and scandium were all unknown when he developed the table and when discovered they had exactly the properties predicted.
We still use the same framework today. The number of known elements has increased from 63 to 118, and through quantum mechanics we understand why the patterns exist, but Mendeleev would immediately grasp the content and what it meant.
We make practical use of most of the elements to build our world
So far, an exciting story of human ingenuity and discovery, but why should we be thinking about it today? The periodic table is the book of the stuff we build the world from. We use most of the 90 stable elements found on the earth in industry. Solutions to the global challenges of population growth, climate change and resource limitations increasingly depend on electrical, electronic, computing and communications technologies. These, in turn, depend on the use of many different elements.
“The periodic table is the book of the stuff we build the world from”
Critical raw materials represent a big risk to the global economy
Unfortunately, not all elements are equally available. Some are in high demand and hard to come by. Critical Raw Materials (CRM’s) or endangered elements are materials essential for a modern economy and where there is a risk to future supplies.
Risk factors include:
- Concentration of primary supply – how many countries are significant suppliers?
- Reserve distribution – how widely distributed are proven reserves?
- Political stability of suppliers – what is the risk of disruption of primary production?
- Companion fraction – how much is produced as a side stream from a bulk material and therefore dependent on the economics of the primary product?
- Substitutability – are alternatives available for the key applications?
- Recyclability – can it be recycled at end of life, and is it being recycled?
A good example of CRM’s are the rare-earth elements used to make high-power magnets. These are used for everything from wind-power generation, through electric cars to computer hard drives and smartphones. Current generation wind turbines use about 500 kgMW-1, 2.5kg for the electric motors in an electric car, 80g for an electric bike and much less than a gram for a smartphone.
‘Rare-earth element’ is a slightly confusing name as they are not that rare. The problem is that they don’t come concentrated in nice compact rock strata that are easily mined. So we have a limited supply at an economic price, and we are rapidly ramping up demand with the switch to a low-carbon economy.
The magnets in a wind-turbine or an electric car are in nice big lumps and can be recovered and reused or recycled economically. The magnets in a mobile phone are tiny compared to the size of the whole phone and hard to recover. There are now more mobile phones than people on the planet with over 1.5 billion sold in 2017. Most of these end up in landfill where recovery is difficult.
We need to find a better way of using these CRM’s or we are going to run out.
Finding a better way to make the electronic devices we depend on
There are four possible strategies for tackling the problem of critical raw materials:
- Find new reserves and extract them more efficiently
- Find substitute materials that are more readily available
- Improve efficiency to get more of the effect out of less material
- Get better at reusing and recycling key materials; moving towards a circular economy
In practice, all these approaches are being explored right now. There will be exciting opportunities for both fundamental research and commercial innovation in substituting, using efficiently and recycling CRMs. Opportunities in everything from fundamental chemistry and materials science to the design and production engineering of consumer products. Opportunities that will be big future markets for someone.
A more thorough review of critical raw materials is published here.