Eriez® Suspended Electromagnet – World Class Design, Built Aussie Tough!
This was originally published by Eriez.
Above Image: Eriez’s Suspended Electromagnet in action above a conveyor belt. Image Credit: Eriez.
The state-of-the-art Eriez Suspended Electromagnet (SE) is widely used in the mining industry. When installed and maintained correctly, it can operate effectively and efficiently for years under the harshest of environments.
Removing damaging tramp iron when conveying bulk materials is an important step to effectively increase plant availability and protect expensive downstream mineral processing equipment.
Both manual and self-cleaning SE magnets are typically mounted over a conveyor belt to remove large pieces of tramp iron such as rebar, nuts, bolts and other steel contamination that represent a hazard to downstream crushers, mills and pulverisers.
They also remove sharp metal rods (i.e. pokers) that damage or tear conveyor belts, typically at transfer points. It is important that customers choose the right type of SE magnet for the right application however.
Selecting the right SE magnet
An SE magnet can be tailored for a static plant application, in-pit mobile equipment or bulk terminal loading facility – such as iron ore and coal ship loaders.
Key selection factors include burden depth, belt width, suspension height, position and tramp iron size and shape. Other factors are belt speed and incline, material density and maximum lump size.
While primarily designed to capture larger masses, such as roof bolts, hammerheads and star pickets, SE magnets can also be adjusted for smaller tramp as well, such as M24 nuts.
The required magnet strength increases as the belt width and burden depth increases. For example, a 1066mm square SE magnet suspended at 330mm can pull tramp iron through 280mm of burden. A larger belt with a magnet height of 762mm can pull tramp through 711mm of burden. Eriez has SE magnets for belt widths up to 2440mm.
A larger belt width and a deeper burden increases the volume and mass of material on the belt, which increases the amount of material through which the magnet has to pull the tramp metal. As belts move faster, the force needed to remove the tramp also increases as the magnet has less opportunity (i.e. less time) to pull out the ferrous contamination.”
Standard vs. custom components
SE magnets consist of several standard components necessary to provide the magnetic force required to remove steel contaminants. These include the coil, core, back bar and steel enclosure. Collectively, they provide the magnetic circuit for the duty; 99 per cent of Eriez SE magnets come with coils fully immersed in cooling oil.
The oil effectively controls heat and moisture – the greatest enemies of electromagnets – by keeping the coil relatively cool while maximising the magnetic strength. Eriez is the only manufacturer to incorporate an expansion tank to ensure the coils are always completely submerged.
The advantage of the expansion tank which only Eriez utilises is that this arrangement makes sure that the coils are always 100 per cent submerged and as the magnet gets hot and oil expands, it is contained in the expansion tank.
In comparison, suspended electromagnets that don’t include this approach will always have portions of their coils uncovered because as the oil heats up, it expands and seeps out of the magnet pressure relief valve.
A small percentage of SE magnets also utilise air-cooling and contain no oil. This type of magnet is generally used in areas designated as hazardous, such as gassy or dusty locations. Permanent suspended magnets (non-powered) can also be used for these applications where the strength and deep reach of an electromagnet is not required.
Manual cleaning vs. self-cleaning
Manual clean SE magnets are for low frequency tramp occurrences. The magnet is moved away from the belt and the power is shut down to release the accumulated tramp into a skip.
A potentially higher incidence of tramp requires a self-cleaning option to continually operate and propel accumulated tramp from the magnet face. Another advantage here is that self-cleaners don’t require manual intervention.
Eriez is recognized as world authority in separation technologies. For more information please call us on +613 8401 7400, email email@example.com or visit our website eriez.com.au.