Shards of plastic, metal, and fiberglass are spit out the other side (below). The shredded phones are heated in ovens that incinerate the plastic. What’s left goes into a melting furnace to produce a metal alloy covered with a brownish layer called slag, which consists mostly of silica. The slag is removed and later sold for use in shingles and road construction.
The remaining alloy is cooled into bars.