Wet drum separators are used in Dense Media Separation (DMS) plants for the recovery of magnetic particles from the dilute medium. They must recover the maximum amount of magnetic particles at the highest possible density.
A wet drum separator consists of a feed box where slurry in initially introduced to the separator, this slurry is then presented to the magnet drum via feed pipes.
The magnet drum consists of a stationary magnet arc around which a drum rotates. The drum is partially submerged in the tank. When the ferromagnetic [medium] particles in the slurry are introduced into the magnetising field produced by the magnet, they first align themselves with the lines of force. The individual magnetic particles are magnetised as they enter the magnetic field. They become induced magnets and join together to form chains or agglomerates which are attracted to the drum. The attraction of magnetic particles to each other increases with the amount of magnetic particles in the feed. When the magnetic force acting on the flocs exceeds the opposing forces, the flocs attach themselves to the drum surface. Flocculation occurs more readily with a “thick” slurry than with a “dilute” slurry, where the magnetic particles are far apart from each other.
The drum contains a radially arranged ferrite magnet assembly with steel poles [RADMAX] between the magnets to concentrate the flux density this provides a strong magnetising field [2000 gauss] and high magnetic gradient at the feed point. The strong magnetising field profile on the drum surface, which allows capture and travel of medium along drum shell until drum shell moves out of the permanent magnet field.
In a counter rotation [CR] tank the drum direction is moving against the feed direction and magnetics attracted to the drum surface are immediately discharged into a chute under the feed box as the moving drum and particles are transported out of the strong magnetic field. Non-magnetic particles / grit and water which are unaffected by the magnetising field, leave the tank through the tailings discharge outlet and weir overflow. A separates compartment with weir can be provided to provide recycled clarified water overflow for re-use in the plant [CRO]. The CRM type tank is able to sink high levels of non-magnetic material.
In a con-current tank [CC] the slurry is introduced into the feed box and flows in the direction of drum rotation. Magnetic particles attach themselves to the drum and are transported by the rotation of the drum, to a point beyond the effect of the magnetising field, where they are discharged.
Level control in the tank is provided by use orifice insert rubbers for CR, CRO, CRM and CC types of tanks, restricting the water flow form the tank increases level further submerging the drum and removing them increases outflow reducing the water level in the tank.
In a self-levelling [CRS] tank level control is automatic which is ideal for plants with fluctuating feed rates, pulp level is maintained by the lack of an orifice in the bottom of the tank, and grit can escape through a small slot before a series of removal weir bars. The water level is dictated by the height of the weir bars.
The RADMAX wet drum separators Recover the maximum amount of magnetic particles, at the highest possible density while reject grit or slimes
Main applications are:
Recovery of magnetite or ferrosilicon in heavy / dense media coal washing or mineral processing plants
Removal of ferromagnetic particles from materials being processed in slurry form
Removal of magnetite from spiral heavy mineral concentrate or magnetite / pyrrhotite from copper nickel ores
Typical particles size range separated range from 45 microns up to 5 mm
High Magnetic Gradient and measurable 2000 gauss flux density on the drum surface using C8A ceramic ferrite magnet and steel pole circuit in radial arrangement
Capacity pulp volume flow rates of 150 m³/hr per metre drum width
High magnetics recovery and low losses even at high solids loading rates
99.9% recovery efficiency in a single stage machine
Able to recover magnetic particles in slurries with very low magnetics content,
High concentrate densities easily achieved
Drum gas purge valves safety feature for FeSi applications
Maintenance friendly drum components, sealed for life drive end bearing, non-drive bearing can be changed “in-situ
Advanced drum component sealing and ingress protection arrangement
Modular magnet element using support column instead of solid shaft, detachable stub shafts on either column end
Direct Drive Shaft mount helical bevel geared motor drive arrangement on detachable drive shaft, low maintenance and easily detachable
non-drive side drum bearings required re-lubrication; non-drive bearing can be changed “in-situ”. The drive side is “lubricated for life”
Self-Tensioning Scraper Blade assembly
Can be supplied with various optional parts and configurations (feed manifolds, product chutes, launders, wear wraps, guarding)
The drum comprises of a shell carried on end flanges fitted with sealed, self-aligning bearings.
The shell is made from non-magnetic stainless steel, typically 3 mm thick. The shell can be covered with an optional wear wrap, typically 2 mm thick, of non-magnetic stainless steel or polyurethane.
The drum end flanges are machined from non-magnetic stainless-steel plate.
The feed box and tank (underpan) are an integral construction, fabricated from non-magnetic stainless steel, typically 3 mm thick. The concentrate chute and feed box are lined with polyurea spray on lining.
The support frame is fabricated mild steel sections and painted with a 2 coat epoxy paint system.
The geared motor drives the drum directly coupled to the end flange via a stub shaft.
Drum scraper blade assembly for cleaning any carried over concentrate
