Electrical wire is a conductive metal wrapped in a plastic insulation.
The most common metal used in electrical wire is copper but depending on the conductor, the metal may be aluminum, or sliver.
Aluminum conductor wire was popular in the 1970’s when copper was at a premium
The plastic that surrounds the wire is also valuable in large quantities
There are millions of feet of scrap wire thrown into landfills every year by contractors, and auto recyclers. This material can be tedious to separate and many companies that scrap this material don’t have time to recycle it.
Some metal scrap yards will also accept electrical wire with the insulation still in place. However the rate per pound received for this material is usually about 50% less than bare material.
The equipment required to recycle electrical wire on a small to large scale varies greatly. But It can be as simple as a utility knife to a large scale granulation and a Density Separator.
Different types of wire require different equipment.
Large cable this is wire that is 8ga to 4/0 and larger. Often this comes from building teardowns, mining operations, industrial renovations, and electrical contractors. This is the easiest to strip and get a good rate for and can often be done on a small scale with just a utility knife.
When you get tired of hand stripping and want to increase production, a roller blade type machine is the next most economical step.
Some of the most cost effective machines for striping wire consist of motorized rollers and a blade to slice through the insulation. These machines can effectively strip wire from large cable down to 16ga stranded wire.
A wire chopping system is the next progression and that is how most large scale wire recyclers operate.
The most basic of these consist of a Granulator and a Density Separator. The more complex systems will have a pre-shredder, magnetic separator, Granulator, Turbo mill, and multiple Density Separators.
What these Machines do:
Pre shredder: This machine takes bales or bulk amounts of scrap wire and cuts it down to consistent size particles.
This can be a single shaft insert type, dual shaft, or quad shaft shear type shredder. The goal of this is to cut down the wire to small enough pieces that any tramp steel can be separated out and increase the efficiency of the Granulator.
Magnetic Separator: This can be many different types, Simple magnetic conveyor head pulley, Cross belt overhead magnet, Rotating Drum Magnet, ect.
A Magnetic head pulley is a magnetized conveyor belt pulley used on the out-feed end of a belt conveyor. It causes the ferrous metals to stick to the belt and ride it around the pulley, where it is discharged away from the other non ferrous material.
A Cross Belt Magnet, is a large magnet suspended over the flow of material. It usually has a cleated conveyor belt that runs around to discharge caught material.
A Rotating drum magnet, is a magnet mounted inside of a rotating stainless steel drum. Material to be separated is dropped onto the top of the drum, and the ferrous material will be discharged in the opposite direction of the nonferrous.
Most better systems incorporate more than one of these strategies to get ferrous material out of their flow.
Granulator: This is the machine that chops the wire up into particles small enough that the metal can be separated from the plastic. The amount of throughput depends on the size of the machine, screen size, and input material size.
Granulator Screen Size depends on the material being processed. For large cables a screen size of 3/8” – 1/2” may be acceptable. For smaller wire 1/8” – 5/16” will work. The goal is to get the wire down to a size that liberates all of the metal from the plastic. However when processing wire thinner then 16ga the granulator might not completely liberate it.
Granulator size just depends on your required throughput and what can be afforded. Most systems use solid rotor granulators from 30 – 150hp.
Turbo Mill: This machine is similar to a hammer mill but with a different rotor design. The purpose of the turbo mill is to liberate and densify fine wire. If processing fine communication wire a turbo mill is a must.
Density Separator: There are a few different types of these, wet type, up draft,zig zag, ect.
The wet type works on the same principle as panning for gold. The material is put onto a vibrating table and washed down with water. The denser copper goes one direction while the less dense plastic is washed away. These are often used as the very last stage to harvest the ultra fine copper particles.
The Up draft works by running the material over a vibrating screen, while air is blown through is from below or sucked through from above. This causes the denser copper to be thrown in the direction and the plastic falls off of the face. Because of it’s adjustability to different particle sizes, it is the most common type used.
A Zig-Zag separator works great when the copper particles are large, 1/4” and bigger. It is a tall narrow box with angled baffles. Air is drawn through from the top and the material is fed in through an airlock a few baffles down from the top. As the denser particle fall through and out the bottom. The lighter plastic is sucked out the top.
Moving the chopped wire: This is usually done using a combination of Belt conveyors, augers and air conveyors.