Monday, 19 August 2019 15:57

Boost for recycling of rare earth metals for a green economy

The University of Birmingham has been awarded €4m to set up a pilot facility to reclaim rare earth metals from scrap as part of an EU-funded Horizon 2020 project. The facility will focus on recycling magnets made of neodymium, boron and iron. These are found in hard disk drives, household appliances, electric vehicles and wind turbine generators, and are increasingly important in the transition to a green, low carbon economy.

In the last 30 years their use has increased exponentially, and demand is expected to rise to the tens of thousands of tonnes by 20301. China produces around 80% of the world's rare earth metals, and currently less than 1% is recycled – which means it presents an exciting circular economy opportunity. Additionally, there has been significant volatility in the price of rare earth metals in recent years, and recycling the magnets will help protect the supply chain for Europe's manufacturing base.

The grant will fund the development of a complete European supply chain that is capable of producing 20 tonnes of recycled magnets a year that would otherwise go to landfill.

rare earthA robotic sorting line will locate and concentrate the rare earth magnets from scrap at Tyseley Energy Park in Birmingham, recycling facilities will extract the metal alloy powders, and these will be used to manufacture recycled magnets in plants in the UK, Germany and Slovenia.

An innovative process developed by University of Birmingham researchers will be a key aspect of this new supply chain.

Previous methods of extracting rare earth metals required disassembly and removal of the magnet. However the new process uses hydrogen to break down magnetic metal alloys into a powder, which is easily separated from the remaining components, thereby saving time, labour and money. The approach also allows the recycling unit to process multiple items at the same time.

Professor Allan Walton, from the School of Metallurgy and Materials at the University of Birmingham is one of the inventors of the process. He commented: "Rare earth magnets are used in practically every application that uses electricity to produce motion, and underpin industries that are worth more than £1trn worldwide. However both the price and supply have fluctuated considerably over recent years. This means there is considerable opportunity for cost-efficient technologies, which make recycling viable in the long-term."

Recent studies have indicated that magnet recycling could emulate the stainless-steel market, where 25% of demand is met by secondary material4.

The EU's Horizon 2020 research and innovation programme awarded a grant of €14m to SUSMAGPRO (Sustainable Recovery, Reprocessing and Reuse of Rare-Earth Magnets in a Circular Economy), an industry-based consortium, which consists of 19 project partners and one associated partner from nine European countries. Of this, €4.696m was allocated to the University of Birmingham to build a scaled pilot system for Hydrogen Processing of Magnet Scrap (HPMS).

The new supply chain will be capable of producing 20 tonnes of recycled magnets a year. A robotic sorting line in Sweden will locate and concentrate the rare earth magnets from scrap, production facilities in the UK, Germany and Sweden will extract the magnet powders from sorted scrap, and these alloys will be used to manufacture recycled magnets in plants in the UK, Germany, Denmark and Slovenia. It is expected that the facilities will process scrap from a range of sources, from small domestic appliances to larger industrial machinery, up to the size of wind turbines.

HPMS – Hydrogen Processing of Magnet Scrap - This patented process uses hydrogen decrepitation, a process developed at the University of Birmingham by Professor Rex Harris, as a cost-effective and efficient way of extracting rare earth magnets from redundant or broken products. Hydrogen preferentially enters the rare earth metal, and causes an expansion in volume. The structure cannot cope with such a large volume expansion and 'decrepitates' as grains break away from the material forming a fine powder. A safe mixture of hydrogen and inert gas at a low pressure causes magnets to decrepitate within a few hours. The de-magnetized alloy is then removed by screening and can be reprocessed directly back into new magnets as an alloy powder.