Article in Chemical & Engineering News (C&EN) includes CMI leader Ikenna Nlebedim and his research at Ames National Laboratory:
With DOE funding, materials scientists at the Ames National Laboratory have developed a clever chemical process to recover rare earths from hard drive magnets. Rare earth recovery methods proposed so far dissolve the elements using acids, but the magnetic material first needs to be separated from pulverized e-waste, such as hard disk drives, and then demagnetized and oxidized.
Ikenna Nlebedim and colleagues instead put the entire shredded disk drive in a copper-based solution that selectively dissolves the rare earths, leaving behind other metals for downstream recovery. The basics behind the simple process are taught in high school chemistry, Nlebedim says. “When you put a nail in a copper salt solution, after some time the nail is covered with copper because of ion exchange. Copper from the solution comes out as metallic copper, and iron goes into the solution. Instead of iron, we are using magnets, which are 70% iron and contain rare earths.”
The researchers currently use an oxalate-based material to extract the rare earths from the solution. Finally—and this is a key advantage—they are now developing a process to produce rare earths in a form that can be directly converted to metals. Most recycling technologies create rare earth oxides, which are typically converted to metals using harsh hydrofluoric acid. This conversion step is one of the reasons why the US sends rare earths outside the country for processing, he says. “The US is now the second-largest rare earth producer, but we don’t have domestic capability to convert those rare earths to metal.”
About a 20 min drive west of Ames, Iowa, in the town of Boone, TdVib is processing over 1 t of disk drives per batch in a pilot plant using the technology it licensed from the national lab. The company continues to optimize the technology. “When they licensed it from us, the efficiency of recovery of rare earths from e-waste was 70%. Now they are at 90%,” Nlebedim says.
See the full story: Electronic waste is a gold mine waiting to be tapped. How can companies dig in?