Suspended permanent magnets play an important role across Australia’s waste, recycling, quarrying and mining sectors, due to their ability to remove damaging metal contaminants from material streams. Designed to deliver consistent separation, these systems provide a practical solution for improving product quality and maintaining reliable processing in demanding environments.
“Even small amounts of tramp metal can have a significant impact on uptime and operating costs,” said Jonathan Schulberg, business development manager, Heavy Industry Asia Pacific Region at Eriez.
“Suspended magnets are often the first line of defense, helping operators protect critical equipment and maintain consistent throughput.”
At the core of separation technology specialist Eriez’s range of suspended permanent magnets is a carefully engineered magnetic circuit constructed from ceramic magnetic materials.
These materials are arranged in specific patterns to generate a magnetic field capable of extracting ferrous metals from conveyed materials. Because the magnets are permanently charged, they operate without the need for an external power source, delivering continuous protection and consistent performance in a wide range of applications.
“Because permanent magnets don’t require an external power source, they offer a simple, highly reliable solution—particularly in remote or mobile applications where power availability and maintenance access can be limited,” Schulberg said.
These magnets are typically installed above conveyor belts or at key transfer points where materials are in motion. Their primary function is to remove tramp iron, which includes unwanted ferrous items such as nails, screws, bolts and fragments of steel. These contaminants can cause significant damage to plant and machinery if left unchecked.
The systems are designed to suit a range of operational requirements. Standard units can accommodate conveyor widths from 500 mm through to 2000 mm, with larger configurations available for high-capacity applications. Suspension heights typically range between 200 mm and 400 mm, allowing flexibility depending on the nature of the material being processed and the level of contamination present. Multiple magnetic circuit designs allow systems to be tailored to specific conditions such as belt speed and the frequency of tramp metal occurrence.
“No two operations are exactly the same,” Schulberg said. “Selecting the right magnetic circuit and installation configuration ensures the separator performs optimally within the specific conditions of each site.”
Hydraulic and electric motor options are available to support different configurations, particularly where self-cleaning mechanisms are required.
Beyond waste and recycling, the technology is used in mining and quarrying to protect downstream equipment from damage caused by stray metal. In these environments, suspended magnets play a role in improving product purity, particularly in applications involving aggregates or recovered materials, where the presence of metal contaminants can compromise quality.
These separators are also effective in municipal solid waste processing, where they are used to recover steel cans and other recyclable metals. In timber recycling, they remove embedded nails and screws from waste wood, enabling safer handling and further processing.
For more demanding industrial environments, electromagnetic separators may be used instead of permanent magnets.
These systems generate a magnetic field through an electrically powered coil, often housed within an oil-filled assembly to manage heat and maintain performance.
Electromagnets are usually used in heavy-duty applications involving materials such as coal, limestone and sand, where higher levels of magnetic force are required. While they offer greater strength, they also require a continuous power supply and additional maintenance compared to permanent systems.
“The choice between permanent and electromagnetic systems ultimately comes down to the application,” Schulberg said. “Higher burden depths and more demanding materials may require the additional strength of an electromagnet, while permanent magnets offer a lower-maintenance alternative for many standard applications.”
Cleaning methods are another important consideration in the design and operation of suspended magnets.
Manual-cleaning models are suited to applications where only occasional or small amounts of tramp iron are present. These units require periodic removal of accumulated metal, usually during scheduled maintenance. In contrast, self-cleaning models incorporate a short belt conveyor that continuously removes captured metal from the magnet face. This automated system includes a rubber belt, bearings, frame and motor-driven mechanism, ensuring that the magnet remains effective without interrupting production.
Proper installation plays a critical role in achieving optimal performance. The preferred configuration is to position the magnet over the trajectory of material as it is discharged from a conveyor, often referred to as in-line installation. In this arrangement, the material moves directly towards the magnet, allowing its momentum to assist in the separation process.
“Positioning the magnet correctly relative to the material trajectory can significantly enhance recovery performance,” Schulberg says.
Where conveyor speeds are lower and the material trajectory becomes more vertical, the magnet may need to be positioned closer to the head pulley to maintain efficiency. In some cases, a stainless-steel head pulley is used to minimise interference with the magnetic field.
An alternative configuration involves mounting the magnet across the conveyor belt before the discharge point, known as cross-belt installation. While this approach can be effective in certain situations, it is generally less suitable for high-speed conveyors, where the reduced interaction time between the material and the magnetic field can limit performance.
The simplicity of installation has also helped make Eriez suspended permanent magnets a standard feature in many bulk handling systems. Their ability to operate without interruption, coupled with minimal maintenance requirements, supports long-term reliability in a range of industrial settings.
As industries continue to focus on efficiency, safety and resource recovery, the role of magnetic separation is expected to grow. Suspended permanent magnets offer a proven and adaptable solution, helping operators manage contamination, protect valuable equipment and improve overall process outcomes without adding unnecessary complexity to their operations.