Bikes, bowling balls, and the balancing act that is modern recycling (2015)

Recycled materials are only valuable if they’re pure—a collection of a single type of metal or plastic that can serve as a feedstock for manufacturing or other industrial processes. As barges and trucks arrive at the facility, the material (often still in its clear bags) is dumped as a single stream onto a large conveyor. Again, most other materials fall immediately off the end of the conveyor and drop onto a new one below; the drum lifts all the remaining metals across to a separate conveyor.

Source: arstechnica.com