The demand for special metals used in the manufacture of electronics is booming, but a few countries control much of the world's supply. Germany is looking to reduce its reliance on imports by exploiting the metal that is thrown away in trash. Urban mining could become big business.

Thierry Van Kerckhoven has an eye for hidden value. The Belgian can look at a pile of shredded scrap metal from electronic devices and recognize what it is made of. Not only that, he can tell how much it's worth.

Kerckhoven works as a buyer of such waste in the world's largest recycling facility for complex precious metals in Hoboken, a section of the Belgian city of Antwerp. The Umicore Group owns the facility, where deliveries are stored in individual concrete bays. Kerckhoven removes his sunglasses and surveys his treasures.

The powdery and shiny material in Box 2051 on the far left, Kerckhoven explains, used to be printed circuit boards and monitors. The copper in the mixture produces the brown color and the glass makes it shimmer. Kerckhoven can detect the remnants of SIM cards in a pile of colorful bits of plastic in the next bay. He pulls out a handful and points to the word "Vivo," a Brazilian mobile communications company.

"Probably excess production," he says, explaining that this is why the material ended up in the landfill. Useless for Vivo, it becomes a valuable resource for Umicore. There are about 100 grams of gold, valued at about €3,400 ($5,000), in each ton of waste in this box. By comparison, a ton of ore from a gold mine often contains no more than 5 grams of the precious metal. When it comes to yield, the recycling plant in Hoboken far outperforms any mine in the world.