urbanmining.org

Products and materials.

Discover the magnets, metals and electronics inside everyday products, industrial equipment and data centers.

Headphones turn electrical signals into sound. Take a closer look at the materials that make it happen.

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3D view of black over-ear headphones
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Headphone components

Inside an earcup, a voice coil, diaphragm and magnet work together to turn an electrical signal into sound.

The same headphone model with one earcup separated into components

The cushion and housing surround the driver. Inside it, a voice coil sits in the magnet’s field and moves the diaphragm as the electrical signal changes.

Neodymium magnets can provide a strong magnetic field in a compact space. They are used in headphone drivers, including the Sony WH-1000XM4.

The magnet, copper coil, steel parts and housing are different material streams. Separating them is a key step in recovering their value.

Small magnet. Powerful sound.

The magnet supplies a steady magnetic field. Current in the voice coil moves the diaphragm, creating the vibrations we hear as sound.

Many headphone drivers use neodymium magnets for their strength and compact size. Recovering these magnets starts with separating them from the surrounding copper, steel and electronics.

The driver cut in half: a disc magnet under a steel pole plate in a steel cup, and the copper voice coil in the narrow gap, carried by the diaphragmThe driver’s disc magnet on its own

How magnets can be recovered

  1. Collected. Magnets from many products are gathered for recovery, once each product’s data, safety and handling requirements are met.
  2. Broken down. Mechanical processing breaks magnets into fragments and granules.
  3. Refined. Refining separates the rare-earth elements, typically as oxides. Iron and other materials leave as a separate stream.
  4. Made new. Oxides can be converted to metals and alloys, then made into new magnets. Each is a separate industrial stage.
Magnets of many shapes, from headphones, speakers, phones, drives and motors, gathered in a trayThe magnets broken down into a heap of granulesA dish of pale rare-earth oxide powder beside a separate dish of dark iron-rich remainderThe oxide beside a rare-earth metal ingot and a stack of new magnet blocks

Sort the wall: 31 still to go Headphones details
Sources

An interactive challenge

Sort the wall.

Thirty-one devices, opened up: servers, phones, appliances, tools and motors. Drag each one to the bin you think is right, a rare-earth magnet, another kind of magnet, or no permanent magnet at all. Open any device first if you want a closer look.

Every answer is what a device most likely holds; magnet type depends on each product’s design.

Data center and IT

Servers, drives and computers: voice-coil magnets in every hard disk, small motors in every fan.

Personal electronics

Phones, wearables and audio: the smallest magnets, in the largest numbers.

Audio

Speakers of every size. Newer and smaller tends to mean rare-earth; older and larger tends to mean ferrite.

Appliances

Kitchen and household equipment: a mix of ferrite, induction and no magnet at all.

Tools and mobility

Cordless tools and e-mobility run on compact permanent-magnet motors.

Motors and parts

What an industrial permanent-magnet motor separates into: magnets, copper and steel.

Wall sorted

0 of 31 right.

0 points

Rare-earth magnets turned up where space is tight and power matters; ferrite where size was no object; and none at all in heaters, induction motors and bearings. That is what recovery sorts for.

What could we recover together?

Reference

Product profiles.

Specs, materials and recovery notes for each product.