Tag Archives: magnets

Eriez ups the capacity of heavy-duty electromagnetic vibratory feeders

Comminution of minerals, Mineral processing, Mining equipment, Mining services,

Eriez® has announced the expansion of its extensive B-series line of heavy-duty electromagnetic vibratory feeders with four all-new B-HC high-capacity models.

Boasting nearly 70-100% greater capacity than previous models, these feeders offer the widest capacity range in the industry, capable of delivering controlled amounts from just a few pounds to 1,089 t of bulk material per hour, the company claims.

The B-HC line of feeders incorporates an innovative electromagnetic drive that features an exceptionally strong rare earth permanent magnetic armature assembly. This system applies power in both the forward and reverse directions of the feeder tray, ensuring precise linearity and control compared to traditional attract-release systems. The coil-and-magnet assembly is encased in epoxy, protecting it from dust and moisture, eliminating coil movement and significantly extending the feeder’s lifespan.

Equipped with a compact and energy-efficient AC control system, Eriez B-HC feeders provide precise, variable-speed feed rate control with accelerometer feedback. The design eliminates sliding and rotating parts, enhancing profitability and productivity by reducing power consumption and maintenance requirements.

B-HC feeders are ideal for head-load applications below a hopper, efficiently metering bulk materials to belt conveyors, screens, crushers and elevators. Standard and custom-engineered trays can be supplied with features such as dust covers, screens and grizzlies. Abrasion-resistant steel or UHMW liners are optional. 

These feeders support both base and suspended mounting options, with the flexibility to choose between undermount or overhead drive configurations. Rob Yandrick, Eriez Global Product Manager-Vibratory, says that the 65B-HC feeder is already demonstrating its superiority among early adopters, including Washington Mills, a leading producer of abrasive grains. Yandrick explains that Washington Mills previously needed their feeder to run at full capacity to meet material feed requirements. In contrast, the 65B-HC can deliver the same feed quantity while maintaining significant feed capacity in reserve.

The full range of high-capacity electromagnetic feeders is being officially unveiled at MINExpo INTERNATIONAL 2024, in Las Vegas, this week.

Bunting ups the design ante with new Permanent Crossbelt Overband Magnet optionality

Comminution of minerals, Mining equipment, Mining services, Sustainable mining, , , , , ,

Bunting says it has developed three designs of Permanent Crossbelt Overband Magnet (PCB), with different magnetic polarity, to suit an ever-expanding range of applications.

Overband Magnets are mounted over conveyors to separate ferrous metal from non-magnetic material and are commonly used in industries, including mining.

The magnetic field of a Permanent Crossbelt Overband Magnet (PCB) is generated by charging ferrite or rare earth magnet blocks mounted inside a stainless steel box with a steel back bar. The steel bar back forces the magnetic field to propagate through and out of the bottom of the magnet box, which would be down towards a conveyor transporting bulk materials. Although all three designs operate under this basic principle, that is where the similarities cease.

The magnetic field of the three designs of PCBs is defined as being either a ‘Single Pole’, ‘Twin Pole’ or ‘Tri-Pole’.

The Single Pole design (PCB Single Pole) is the simplest and most common design of PCB. Constructed with a single magnet block and steel back bar, the north pole sits on the back bar with the south pole at the bottom of the block. The field runs vertical, from north to south, projecting out from the south pole and into material being transported on a conveyor. The Single Pole design removes general tramp metal from a range of products in various applications.

A Twin Pole (PCB Twin Pole) configuration uses two separate magnet boxes, mounted side by side on a single steel back bar, each with a different magnetic pole. The magnetic field flows from south to north (from one box to the other) producing a deep magnetic field that projects away and down from the magnet faces.

The enhanced separation performance of the PCB Twin Pole enables capture of smaller ferrous particles. The twin pole configuration has the advantage of lifting longer and thinner tramp ferrous metal, typically steel rebar, in a flat orientation which aids discharge and reduces belt wear. This characteristic of the Twin Pole occurs due to the different poles of the two magnet boxes attracting opposite ends of the ferrous metal rod, forcing it to remain flat in the field. The Single Pole design attracts one end, resulting in one end striking the belt or face of the magnet box.

The Tri-Pole Permanent Crossbelt Overband Magnet (PCB Tri-Pole) has two additional steel side poles mounted either side, with a gap, of a single central magnet box. Each of the side poles has a magnetic north pole, with the centre of the box being south pole (ie three poles). This generates two magnetic fields running from the box to the steel sidepoles. The sidepoles reduce flux leakage and concentrate the magnetic field downwards toward the product.

The greater depth of magnetic field generated by the PCB Tri-Pole results in a higher suspension height of the Overband Magnet, which is ideal for deeper troughed conveyors and higher burdens of material, Bunting says. The Tri-Pole model captures smaller ferrous metals that are difficult to separate with a PCB Single Pole.

An added advantage is that the shape and direction of the magnetic field limits any magnetisation of the Overband Magnet frame.

Bunting offers up armour for Overband Magnet applications

Bulk handling, Equipment maintenance, Mineral processing, Mining equipment, , ,

The highest wear part on an Overband Magnet is the belt that transfers the separated metal away from the conveyor and into a collection area. In order to reduce such wear in applications from mining to recycling to biomass power plants, Bunting has developed a special lightweight armouring for the rubber belt.

In operation, an Overband Magnet sits over a conveyor transporting materials such as mined ore. The magnetic field of the Overband Magnet, generated by either a permanent magnet or an electromagnetic block, attracts ferrous metal from the conveyed material up and onto the revolving self-cleaning belt. Rubber upstands on the belt catch the lifted metal, transporting it away from the conveyed material into a separate collection area.

The force of the ferrous metal striking against the self-cleaning rubber belt is significant due to the magnetic attractive energy of the permanent or electromagnetic block increasing as the metal moves closer to the face. This means the metal is accelerating into the belt. The moving belt becomes sandwiched between the lifted metal and the magnetic block momentarily, until the upstand catches and drags the item away and out of the magnetic field.

Applications in which self-cleaning belts experience high levels of wear include:

  • When there are high amounts of ferrous metal present in the conveyed material;
  • When the ferrous metal is large and heavy;
  • When there are nails or thin and sharp ferrous metals; and
  • When the magnetic block has additional magnetic force, as with the ElectroMax and ElectroMax-Plus models.

To combat the excessive wear and extend the life of a self-cleaning belt, Bunting’s engineers designed a lightweight but heavy-duty armouring for the belt. There were other options, including special wear-resistant belt coatings and other types of rubber belt, however the armouring provided unrivalled protection, significantly lengthening belt life, Bunting says.

The armouring on the rubber belt is comprised of high-density polyethylene (HDPE) slats. Each slat is 100-mm wide and 10-mm thick, with a length to suit the model of overband magnet. The slats are fastened to the belt using special 304 stainless steel elevator bucket bolts and nyloc nuts.

“The introduction of this design of armoured belt has proven very popular,” Adrian Coleman, Bunting’s Technical Director, says. “Other types of belt armouring have proven unsuccessful, but the HDPE has worked exceptionally well.”