Master Magnets Ltd

Recycling aluminium explained - Case Study


Courtesy of Master Magnets Ltd

A major magnetic equipment manufacturer has successfully solved numerous Aluminium Recycling problems world wide. Master Magnets Ltd is a world leader in the field of Metal Separation applications, they are now willing to share the secrets behind their success.

The recycling of aluminum generally produces significant cost savings over the production of new aluminum even when the cost of collection, separation and recycling are taken into account. Over the long term, even larger national savings are made when the reduction in the capital costs associated with landfills, mines and international shipping of raw aluminium are considered.

The environmental benefits of recycling aluminium are also enormous. Only around 5% of the CO2 is produced during the recycling process compared to producing raw aluminium (and an even smaller percentage when considering the complete cycle of mining and transporting the aluminium). Also, open-cut mining is most often used for obtaining aluminium ore, which destroys large sections of world's natural land.

Recycling Aluminium has been further improved through Master Magnets high performance ‘Eddy Current Separator’. In the late 80’s Master Magnets recognized a need in the market for a machine which can separate Aluminium (Non Ferrous) from other metals and non metallic’s (E.g Iron and Plastics). Therefore Master Magnets launched the Eddy Current Separator into the market place.

Operating principle

An Eddy Current Separator basically consists of a short belt conveyor with its drive at the return end. Inside the delivery pulley a rotor fitted with magnets spins at high speed generating a high frequency alternating magnetic field. In a similar manner to electric motors the alternating magnetic field sets up an electric current in conducting metals within its influence, which in turn produces a magnetic field opposing that of the rotor. Conducting metals are therefore repelled by the rotor, and tend to jump away from it. In operation non metallics are discharged as from a normal conveyor, non ferrous metals because of the repulsive force take a higher trajectory passing over a splitter plate placed between the two flows.

The separating efficiency depends on the frequency of the alternating magnetic field, the strength of the magnets, the speed of the conveyor and the position of the splitter plate. All of these factors should be taken into account when selecting a machine for a particular application. In order to allow non ferrous metals to be repulsed by the rotor material on the conveyor should ideally be in a monolayer, so throughput will depend on the density and particle size of the material, and the width and speed of the conveyor.


Eddy Current Separators are increasingly used wherever separation of non ferrous metals from a product stream can give a more valuable product, whether the end use is in recycling, reduction of waste, raw material production or any other process where separation is beneficial. Typical examples of applications are :-

• Separation of non ferrous metals in auto shredder residue
• Separation of non ferrous metals from solid waste incinerator ash
• Sorting aluminium beverage cans from non metalllics.
• Removal of contamination from crushed glass cullet
• Extraction of contaminants from process lines
• Separation of non ferrous dross from foundry sand
• Non ferrous metal removal in WEE recycling plants
• Removal of aluminium components in UPVC window recycling

At the heart of many Material Recycling Facilities (MRF’s) an Eddy Current Separator will remove non ferrous metals from domestic, commercial and industrial waste.
Technology from Master Magnets

Master Magnets ECS designs incorporate the latest generation neodymium-iron-boron rare earth magnetic elements to give the high field strengths necessary for efficient separation. Careful design of the rotor within the outer pulley shell ensures that the product is as close as possible to the magnets, as does the selection of high quality thin section conveyor belt.

Various combinations of rotor size and magnetic design are available depending on the application. The standard rotor functions well on such applications as municipal waste recycling. The ‘Fines’ rotor will treat small particle sizes where high rejecting forces are required, and a special design treats coarse, light material such as beverage cans. All are available in widths from 300mm to 1500mm depending on the throughput required. Below is our latest version of the eddy current separator, which is lower in cost and specifically designed for can sorting.

Master Magnets can supply a complete solution to a non ferrous separation problem, from laboratory sample testing to design and installation of a complete separation plant. After careful consideration of the operational requirements the plant will be designed to give a long and trouble free life, and to produce separated materials to the customers specification. In house experience will be drawn on to ensure that hoppers, feeders, conveyors, magnetic separators, and all other parts of the plant are compatible, and together function efficiently.

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