Engineering researchers from the University of Leeds have discovered how to recover significant quantities of rare-earth oxides, present in titanium dioxide minerals. Rare-earth oxides are useful in many applications, such as the manufacture of wind turbines, energy-efficient lighting, and hybrid and electric cars.
Rare earth metals are a group of 15 chemically similar elements, grouped separately in the periodic table, known as lanthanides. Their unique properties - catalytic, chemical, electrical, metallurgical, nuclear, magnetic, and optical - have led to their use in an extraordinarily wide range of applications.
Despite their name, 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.
The oxides are, however, found relatively frequently alongside titanium dioxide - a versatile mineral used in everything from cosmetics and medicines to electronics and the aerospace industries - which the Leeds professor Animesh Jha has been researching for the last eight years.
Professor 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 percent purity. Not only does the technology eliminate hazardous wastes, 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 percent, although through better process engineering we will be able to recover more in the future," says Professor 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."