MINERAL SEPARATION
The Weir Cavex ® 2 high-efficiency cyclone it says marked a new era in hydrocyclone separation technology with the ability to reduce turbulence and improve classification, with capacity increase of up to 30 %
Catching the cut point
In this separation technology update, Paul Moore focuses on magnetic methods, plus the latest on hydrocyclones, spirals & shaking tables
This annual article is a chance to look at key mineral processing methods that rely on magnetic, density and gravitybased separation.
Starting with magnetic separation, it continues to play an important role in iron ore processing, particularly as the mining industry looks to improve efficiency while reducing environmental impact. From tramp metal removal to dry beneficiation, developments in high-intensity magnetic separation are enabling new approaches to ore upgrading without reliance on water.
16
At the front end of iron ore processing, tramp metal removal remains critical. Large ferrous objects such as excavator teeth or hand tools can cause catastrophic damage to large jaw and cone crushers. Highpowered electro overband magnets are therefore commonly used ahead of crushing stages to capture this material, protecting downstream equipment, maintaining operational continuity and reducing the risk of costly unplanned maintenance.
Beyond equipment protection, one of the major drivers for innovation in iron ore processing is water reduction. It is estimated that between 2,000 and 5,000 litres of water are used per tonne of iron ore produced. A significant portion of this consumption occurs during concentration and beneficiation. As water scarcity and environmental pressures increase, dry processing flowsheets are gaining attention as a viable alternative.
Recent work with global mining companies and research institutions has focused on developing dry processing flowsheets using high-intensity magnetic separation. Test work carried out at Bunting’ s customer experience centre in Redditch, UK, has involved concentrating ores and tailings across a wide range of size fractions using multi-stage magnetic separation, allowing assessment of where individual separator technologies perform most effectively.
For coarser material in the 25-50 mm size range, Gordon Kerr-Whale, Bunting’ s Marketing and Communications Manager – Equipment told IM that a combination of a rare earth permanent drum magnet and a high-intensity separation conveyor( HISC) has proven effective as a pre-sorting stage. This approach increases the iron content of material sent for further size reduction while removing grinding iron and small tramp metal. The rare earth drum utilises a permanent magnet system mounted within a rotating stainless steel drum, with a 180 ° magnetic arc that creates distinct magnetic and non-magnetic zones. In testing, top feeding enabled clean separation of magnetic material.
Material then passes onto the HISC, which uses a high-powered permanent magnetic head pulley with a specialised pole arrangement to generate high magnetic peaks on the belt. A thin, robust belt design keeps the product stream close to the magnet, maximising separation efficiency. Across all samples tested at this size range, this method improved iron content and reduced the volume of inert material reporting to further comminution. The same approach was also effective in tailings applications, separating higher iron content material from lower-grade streams.
For intermediate sizes between 1 and 5 mm, a multi-step process using a rare earth drum followed by a rare earth roll separator was applied. The rare earth roll is a conveyor-based separator featuring a tightly spaced pole configuration that produces a steep magnetic field gradient. Combined with a thin Kevlar belt, this design is well
International Mining | MARCH 2026