Downstream of the shredder and the yard floor, sorting plants separate mixed metals into the grades that sell: eddy-current separators lift non-ferrous out of fluff, sink-float plants split Zorba into Twitch and heavies, and sensor sorters pick alloys from a moving belt.
Downstream of the shredder and the yard floor, sorting plants separate mixed metals into the grades that sell: eddy-current separators lift non-ferrous out of fluff, sink-float plants split Zorba into Twitch and heavies, and sensor sorters pick alloys from a moving belt.
Magnetic separation comes first: drum and overband magnets take the ferrous fraction out of shredder output and mixed loads. Eddy-current separators then spin a rotor of alternating magnets beneath a belt; non-ferrous metals passing over it are thrown forward by induced currents while plastic and glass fall straight down. That product is Zorba.
Sink-float (heavy-media) plants suspend the Zorba in a slurry of a set density so that aluminium floats and copper, brass, zinc and stainless sink — the classic way of making Twitch. Sensor-based sorters do it dry: X-ray transmission (XRT) sorters distinguish metals by density on a belt and blow out the heavies with air jets; X-ray fluorescence and LIBS sorters identify alloys piece by piece at belt speed, separating cast from wrought aluminium or 304 from 316 at tonnes per hour.
China’s import standards made mixed scrap unsaleable without upgrading, so sorting plants were built in Malaysia, Thailand, India and in the exporting countries themselves. Carmakers wanting recycled aluminium of known alloy, and stainless mills wanting cleaner feed, have pushed the technology further. A yard that sorts sells Twitch, sorted brass and graded stainless instead of Zorba, and keeps the margin.
The big shredder makers supply downstream plants; specialist sorter makers in Germany, Norway, Belgium and the United States supply the sensor sorters; eddy-current and magnet makers are found in Germany, Italy, India and China.
Long-established makers of this class of machine. Names first; the buttons go deeper.
| Maker | Where | Machines | |
|---|---|---|---|
| Lindemann GmbH (Metso) | Düsseldorf, Germany | Shredders and downstream separation plants | |
| Danieli Centro Recycling (Danieli & C. S.p.A.) | Buttrio, Italy | Shredders, shears, balers, separation | |
| Steinert GmbH | Cologne, Germany | Magnets, eddy-current and sensor sorters | |
| TOMRA Sorting | Asker, Norway | XRT and LIBS metal sorters | |
| Eriez Manufacturing Co. | Erie, United States | Magnets and eddy-current separators |