Researchers from Leeds University’s faculty of engineering have discovered how to recover significant quantities of rare-earth oxides that are present in titanium-dioxide minerals.
The rare-earth oxides, which are indispensable for the manufacture of electric components, are extracted or reclaimed from the waste materials of another industrial processes.
Despite their name, the 15 rare-earth metals occur more commonly within the Earth’s crust than precious metals such as gold and platinum but their oxides are rarely found in sufficient concentrations to allow for commercial mining and purification.
They are, however, found relatively frequently alongside titanium dioxide – a versatile mineral that is used in everything from cosmetics and medicines to electronics and the aerospace industries – which Leeds University’s Prof Animesh Jha has been researching for the last eight years.
The Leeds breakthrough came as Jha and his team were fine tuning a patented industrial process they have developed to extract higher yields of titanium dioxide and refine it to over 99 per cent purity.
Not only does the technology eliminate hazardous wastes and cut costs and carbon-dioxide emissions, the team also discovered they can extract significant quantities of rare-earth metal oxides as co-products of the refining process.
‘Our recovery rate varies between 60 and 80 per cent, although through better process engineering we will be able to recover more in the future,’ said Jha. ‘But already, the recovery of oxides of neodymium (Nd), cerium (Ce) and lanthanum (La) from the waste products – which are most commonly found with titanium-dioxide minerals – is an impressive environmental double benefit.’
The research has been funded by the Engineering and Physical Sciences Research Council (EPSRC), the former DTI’s Sustainable Technology Programme and industrial sponsor, and Cristal Global in the US (formerly Millennium Inorganic Chemicals) through a PhD studentship for team member Graham Cooke.