Japan's National Institute for Material Science (NIMS) announced that it had developed a new method which is easier to use in recovering rare metals from piles of used products, so-called "urban mine."
In the method, announced on November 26, 2008, discarded electric devices are shredded into pieces of a few centimeters in size before being put into a ball mill and ground, without undergoing disassembling and selection by hand.
By feeding large objects exceeding the ball mill's accepted maximum size limit, structural parts of the wastes made of plastics and aluminum are not ground and left in the form of plates, whereas junctions, ceramics and plating that contain rare metals, are pulverized into fine particles less than one millimeter in size. Through this process, each component can be obtained in a form to be treated easily in the downstream process.
This method, utilizing a ball mill, a simple piece of equipment widely used in conventional pulverization, basically requires no heat or water, and can be operated in urban area as a small size plant.
NIMS considers this to be an optimal system for "urban mines."
