LONDON (Reuters) – The EU will struggle to meet ambitious targets for rare earths in new legislation designed to boost domestic production of crucial minerals and reduce dependence on China.
The 17 silvery-white rare earth minerals are not uncommon in the Earth’s crust. But deposits that are economically viable are harder to find, and the real rarity lies in the complex process of separating them into the materials needed to produce permanent magnets used in a range of critical products.
China accounts for about 60% of global rare earth production, but its share is rising to 90% of processed rare earths and magnet production.
Below are the complex steps that rare earth metals must take to end up as magnets used in electric vehicles and wind turbines – the two main areas that will drive demand in the coming years.
MINE
Ore is first extracted from an open pit or underground mine, crushed and moved to a factory, usually close to the mine site.
The ore contains a small percentage of rare earth elements, but other minerals are removed by flotation, magnetic or electrostatic processing to produce a mixed rare earth concentrate often containing 60% to 70% rare earth elements.
Other operations produce a concentrate of rare earth metals as a by-product of mining waste or from other metals such as mineral sand or iron ore.
RADIOACTIVITY
Certain ore types, such as monazite, must undergo another step to remove radioactive thorium or uranium from the ore, often using acid.
PARTING
One of the most difficult steps is separating the individual rare earth metals. The technology was first developed after World War II in U.S. government research laboratories.
Separation can be achieved using ion exchange technology. It can also be done using solvents such as ammonia, hydrochloric acid and sulfates, although some such chemicals produce toxic waste that can cause cancer.
So-called light and heavy rare earth metals must pass through different separation circuits where individual rare earth metals are extracted.
New, more environmentally friendly technologies are being developed, but they are not yet widely used.
METALS/ALLOYS
Separated rare earth oxides are then converted into rare earth metals by electrolysis.
The most commonly used permanent magnets combine rare earth metals neodymium and praseodymium with iron and boron, which are placed in a vacuum induction furnace to form an alloy. Small amounts of rare earth metals dysprosium and terbium are often added to create more heat resistance in the magnet.
MAGNETS
The alloy blocks are broken down in a nitrogen and argon atmosphere and ground into micron-sized powder using jet mills. This process undergoes a high temperature and pressure process called ‘sintering’ before being pressed into magnets.
