MINERAL SEPARATION suited to separating weakly magnetic and paramagnetic materials.
Bunting adds that rare earth rolls are widely used in silica sand processing to remove fine iron contamination and paramagnetic minerals. Testing has shown that they are also effective in iron ore beneficiation, particularly as reduced particle size improves mineral liberation but demands higher magnetic field strengths for efficient separation.
At the finest end of the size spectrum, below 1 mm, testing focused on two electromagnetic separator types that delivered similar performance, allowing flexibility in equipment selection depending on application requirements.
The first is the magnetic disc separator, where material is conveyed beneath up to three rotating discs. Each disc is energised by two electromagnetic coils, inducing a magnetic field that lifts weakly magnetic and paramagnetic particles from the belt. These particles are discharged once the disc rotates out of the magnetic field. The dual-coil design and adjustable configuration allow highly selective separation, with up to seven distinct product streams possible depending on disc arrangement. This technology is widely used in mineral processing, particularly for mineral-rich sands, and is increasingly applied in the separation of rare earth minerals such as monazite. Testing with a single-disc unit produced three product streams with clearly differentiated iron content.
The second option for this size range is the induced roll separator, another electromagnetic system that uses a highpowered coil to induce a magnetic field into a castellated roll. The castellations generate a very high field gradient. Material is topfed onto the roll, where weakly magnetic and paramagnetic particles are attracted
Bunting Electro Overband Magnets awaiting shipment to mining customers
and discharged from the magnetic field, while inert material falls away immediately. Induced roll separators are well established in the mineral processing industry, particularly in silica sand applications. Test work demonstrated the ability to produce iron-rich and predominantly inert product streams in a single pass, with multi-roll
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