Rare earths extracted from coal byproducts

United States – Researchers from Pennsylvania State University (PSU) and US department of energy scientists have developed a ‘cost-effective’ ion-exchange process to extract rare-earth elements from coal byproducts. Ion exchange involves rinsing the coal with a solution such as ammonium sulfate to release the rare earths bound to the coal.

The 17 rare-earth elements support more than US$ 329 billion of economic output in North America, according to the American Chemistry Council, and the United States Geological Survey expects worldwide demand to grow more than 5% annually through 2020. Rare-earth elements are used in, among many other everyday items, computers, smart phones, rechargeable batteries, electric vehicles, magnets and chemical catalysts. Currently, China produces more than 85% of the world’s rare-earth elements, with the USA in second place at just over 6%.

‘We have known for many decades that rare-earth elements are found in coal seams and near other mineral veins,’ says Professor Sarma Pisupati of PSU’s energy and mineral engineering department. ‘However, it was costly to extract the materials, and there was relatively low demand until recently. We wanted to take a fresh look at the feasibility of extracting REEs from coal because it is so abundant in the United States. Essentially, REEs stick to the surface of molecules found in coal, and we use a special solution to pluck them out. We experimented with many solvents to find one that is both inexpensive and environmentally friendly.’

The researchers used coal byproducts in their study, some of which were discarded or marked as refuse during mining operations owing to poor quality.

Source: ASM International