Scrap Metal Sorting: Magnet Cranes to ABB Robots

Scrap metal sorting decides what a piece of old steel or aluminium is worth, because a smelter pays far more for a clean, known alloy than for a mixed heap. For most of the last century people did that sorting by hand, helped by magnets. This post follows the job from hand picked scrap yards through magnets, shredders and eddy current separators to the laser sensors and AI robots arriving now, including a new aluminium sorting plant in Germany. It also looks at where ABB robots could fit in a scrap yard and what still holds automation back.

A scrap metal recycling yard in the industrial zone of Longview, Washington, 2024. Photo: Quintin Soloviev / Wikimedia Commons (CC BY 4.0)

Hand picking, magnets and the shredder

Scrap sorting used to start with people. During the Second World War households gave up pots, pans and kettles, and in July 1940 members of the Women's Voluntary Service in Welshpool, Wales, piled up aluminium for the war effort. In the yards, workers graded metal from experience and picked copper, brass and lead out of the iron by hand. One of their tests is still in use: hold a magnet to the piece. Steel sticks to it, and copper, aluminium and brass do not.

Women's Voluntary Service members with aluminium pots and kettles collected for the war effort in Welshpool, Wales, July 1940. Photo: Geoff Charles / Wikimedia Commons (CC BY-SA 4.0)

Magnets scaled that test up. A 1942 photograph of an American car salvage dump shows sorted scrap being loaded by powerful electric cranes into freight cars, each type and grade in its own car. The electromagnet on the crane lifts anything made of iron or steel and drops the rest. That made moving steel fast, but a magnet cannot tell one non-ferrous metal from another, so copper wire and aluminium castings were still picked out by hand.

An electromagnet crane lifting sorted automobile scrap at a salvage dump, September 1942. Photo: William Perlitch, Library of Congress via Wikimedia Commons (public domain)

Shredders later turned whole cars into fist sized pieces, and magnetic drums pulled the steel out of the stream. In 1969 William Benson and Thomas Falconer of Eriez Magnetics received a US patent for an electrodynamic separator, the device now called an eddy current separator. Its spinning magnetic rotor throws aluminium, copper and die cast metal off the end of a conveyor while non-metals drop away. It always sits after the magnets, because steel heats up in the eddy current field and can damage the machine. What comes out is still a mix of non-ferrous metals, which the trade calls Zorba and which has to be sorted again.

Flattened cars waiting for the auto shredder at Fields Point, Providence, April 1973. Photo: Hope Alexander, EPA DOCUMERICA / NARA via Wikimedia Commons (public domain)

Laser sorting and robot pickers today

The newest sorting lines read the chemistry of each piece. AlCircle reported on 2 September 2026 that Trimet Aluminium is opening a sorting site in Hamm, Germany, due to start in October with a capacity of 40,000 tonnes a year. Its laser induced breakdown spectroscopy system checks up to 150 pieces a second for silicon, copper, iron and magnesium. Air pulses blow each piece into the right fraction, and a press bales the sorted metal for melting. Trimet says the plant takes over work that outside partners used to do.

Baled aluminium scrap in a container in Dillingen, Germany, 2007. Photo: Lokilech / Wikimedia Commons (CC BY-SA 3.0)

People are now putting numbers on what better sorting is worth. In September 2026 the World Business Council for Sustainable Development said about 2 million tonnes of US aluminium scrap are exported each year, much of it as mixed Zorba. Around 71 percent of recovered US aluminium scrap outside the 3xxx series stays mixed and ends up downcycled. The council estimated that about 35 advanced sorting plants using X ray transmission and laser analysis could add USD 1.9 to 2.3 billion a year in processing value, with each plant handling about 45,000 tonnes a year.

The Max Becker scrap yard in Köln-Ehrenfeld, Germany, seen from the air, 2020. Photo: Raimond Spekking / Wikimedia Commons (CC BY-SA 4.0)

Robot arms take the pieces that air jets cannot move, such as heavy or tangled ones. ZenRobotics' Heavy Picker recognises copper, brass, stainless steel, aluminium and zinc, and can be trained to spot electric motors and wire. Its ZenBrain software reads the sensor data in real time and decides which piece each arm should grab. Swedish scrap processor Skrotfrag installed a three armed line in 2019. One of the largest US steel recyclers ordered seven more units after three went into service in 2024, partly to keep copper below 0.1 percent in recycled steel. ABB's Robotic Item Picker, which uses AI vision to grab unknown items from mixed bins, shows how ABB arms could fit such a line, though no ABB scrap yard project is public.

ABB's Robotic Item Picker uses AI vision to grab unknown items from mixed bins. Photo: ABB

What comes next for scrap sorting robots

Magnets and eddy currents will keep doing the bulk work, because nothing moves tonnes of mixed metal more cheaply. Robots and lasers come after them and clean up the fractions that are worth more when pure. Steelmakers want less copper in their scrap, and aluminium plants want alloy grades they can recast with less fresh metal. Yards will need more sensors per tonne as a result, and the problem looks quite different from the light packaging that curbside recycling robots pick.

A crane magnet loading shredded steel into railway cars, May 1972; magnets still do this bulk work today. Photo: William C. Shrout, EPA DOCUMERICA / NARA via Wikimedia Commons (public domain)

Heavy scrap needs heavy arms. An IRB 6700 can lift loads that would injure a person, while a FlexPicker running ABB's PickMaster software suits light, fast fractions such as shredded aluminium on a belt. Gripping is the hard part, since scrap is often sharp and oily and grippers wear out quickly. Engineers usually plan and test such cells in RobotStudio before the first piece of scrap hits the belt, because a crash on a heavy line can stop the whole plant.

An ABB IRB 6700 lifting a large panel at dhp technology, the size of robot that heavy scrap would need. Photo: ABB

Money and harsh conditions will decide how fast this spreads. Yards are dusty and rough on equipment, and a picker that jams on a tangle of wire costs money every minute it stands still. The WBCSD put the capital cost of its 35 plants at about USD 150 million, for the US alone. Recyclers will also need staff who can retrain vision models and repair robots. Electronics and batteries call for careful disassembly instead, which we covered in our post on e-waste recycling robots.

An ABB FlexPicker cell set up with PickMaster software, the kind of fast picker used on light fractions. Photo: ABB

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