Drum magnetic separator

Magnetic separators introduction

By creating an environment comprimizing a magnetic force (Fm), a gravitational force (Fg) and a drag force (Fd) magnetic particles can be separated from nonmagnetic particles by Magnetic separators.

Magnetic separation – Magnetic attraction force (Fm)
Fm = V x X x H x grad H
V = particle volume (determined by process)
X = magnetic susceptibility (see table below)
H = magnetic field (created by the magnet system design) in mT
(milliTesla) or kG (kiloGauss) 1 kG = 100 mT = 0.1 T
grad H = Magnetic field gradient (created by the magnet system design) in mT/m

Magnetic field and magnetic gradient are equally important factors for creating the magnet attraction force.

Magnetic separation – Competing forces

    • Gravitational force (Fg) is determined by particle size and density.
    • Drag force (hydrodynamic, aerodynamic), Fd, is determined by particle size, shape, fluid density, viscosity, turbidity and velocity.
    • Centripetal force (Fc).
    • Adhesion
    • Electrostatic forces etc.

Magnetic separation – Methods

Low Intensity Magnetic Separation, or LIMS in short

    • Dry and wet methods
    • For separation of ferromagnetic particles
    • Magnetic field intensity up to 300 mT
    • Particle sizes up to 300 mm

Medium Intensity Magnetic Separation, or MIMS in short
• Dry and wet methods
• For separation of ferromagnetic particles
• Magnetic field intensity up to 800 mT
• Particle sizes up to 300 mm

High Gradient Magnetic Separation, or HGMS in short
• Cyclic and continuous methods
• For separation of paramagnetic particles
• Magnetic field intensity up to 2 T
• Limited to processing of particles finer than about 1 mm

Magnetic separation – Separator types

Magnetic separation equipment

  • All LIMS models, wet and dry versions, comprise magnetic drum assemblies mounted in either tanks or dust housings. The magnetic assembly comprises a stationary magnetic array installed in a rotating outer drum. The drum rotation speed and direction are selected for the application in question.
  • Generally coarse material is processed by dry LIMS and fine material by either dry or wet LIMS. The upper particle size limit for wet processing is about 8 mm but with special arrangements coarser material can be processed by wet methods.
  • Dry LIMS – Belt drum separator, or BS in short

    The belt drum separator, BS, is generally used in iron ore beneficiation to either produce coarse final products or for reducing feed mass to following process stages. It is also used for steel slag and pyrite cinder treatment.

    Features
    • Magnetic system with three different pole pitches with alternating polarity (models BSA)
    • Special pole design with fixed polarity in rotating direction for coarse material,(model BSS)
    • For low to high Fe grade feed
    • Belt speeds up to 3 m/s (20 ft/min)
    • Belt feed for even distribution of feed material
    • Adjustable product splitter for product quality control
    • Coarse particle tolerant, up to 250 – 300 mm
    • Basically used in primary stages
    • Can be arranged in single stage or multistage processing
    • Very large unit capacity

    Recommended pole pitch and capacity ranges

    Note: Capacities vary with grade as well as particle size

    Dry LIMS – Belt separator (BSA and BSS)



    Note: At peripheral drum speed 2 m/s (400 ft/min)

    Dry LIMS – Drum separator, DS

    The Dry Drum Separator, DS, is generally used in iron ore beneficiation to either produce coarse final products or for reducing feed mass to following process stages. It is also used for steel slag and pyrite cinder treatment. The metal powder industry uses the separator for final product control.

    Features
    • Magnetic system with four different pole pitches
    • For low to high Fe grade feed
    • Drum speeds up to 8 m/s (1600 ft/min)
    • Top feed
    • Adjustable product splitter for product quality control
    • Coarse particle tolerant, normally up to 20 – 25 mm (3/4 – 1 inch)
    • Basically used in primary stages as cobber and rougher
    • Can be arranged in single stage or multistage processing
    • Can be connected to dust control systems
    • Large unit capacity

    Recommended pole pitch

    Note: pp 25 is intended only for special application

    DS – Capacities

    Note: Capacities vary with grade and particle size

    Dry LIMS – Drum separator – (DS)


    Note: At drum peripheral speed of 2 m/s (400 ft/min)

    Wet LIMS – Wet magnetic separators

  • The wet magnetic separators are generally used in the iron ore industry in several stages of the process from coarse separation to fine concentration of magnetite ore, in single concentration means or in combination with other methods (e.g. flotation, gravity concentration, screening).
  • Wet LIMS are also used in other mineral industries for e.g. preparation of dense media, reduction of pyrrhotite content in base metal concentrates, removal of ferromagnetic contaminants etc.
  • Please always check with Deya Machinery for final selection!

    Wet LIMS – Concurrent CC

    • Medium long magnetics pick up zone
    • Standard magnetic system
    • For low to high Fe grade feed
    • Concurrent operation
    • Tank bottom spigots for tailings flow control
    • Coarse particle tolerant, normally up to 8 mm
    • Basically used in primary stages as cobber and rougher
    • Can be arranged as single stage or multistage units on same level for reprocessing of the magnetic product
    • Large unit capacity
    • Feed density acceptable in a wide range, normally 35 to 45 percent solids by weight

    Wet LIMS – Counter rotation CR and CRHG

    • Extra long magnetics pick up zone
    • Available with either standard or High Gradient magnetic systems
    • For low to high Fe grade feed
    • Counter rotational operation
    • Manually adjustable weir for tailings flow control
    • Coarse particle tolerant, normally up to 3-4 mm
    • Basically used in primary stages as cobber or rougher
    • Also used for dense media recovery
    • Large unit capacity
    • Mostly used in single unit operation but can installed as double units on two levels
    • Feed density acceptable in a wide range, normally 25 to 45 percent solids by weight

    Wet LIMS – Countercurrent CTC and CTCHG

    • Long magnetics pick up zone
    • Available with either standard or High Gradient magnetic systems
    • Countercurrent operation
    • Normally arranged installed as multistage units on same level for reprocessing of the magnetic product
    • Fixed overflow weir for tailings flow control
    • Medium particle tolerant, normally up to 0,8 mm
    • Basically used in cleaning or finishing stages
    • Feed density acceptable in a wide range, normally up to 40 percent solids by weight

    Wet LIMS – Counter rotation froth DWHG

    • Long magnetics pick up zone
    • High Gradient magnetic systems
    • Counter rotational operation
    • Extra large feed box for deaeration of feed slurry
    • Normally arranged installed as a single stage unit
    • Manually adjustable weir for tailings flow control
    • Coarse particle tolerant, normally up to 3-4 mm
    • Designed to improve recovery from aerated (frothy) slurries
    • Used for recovery of magnetics in slurries emanating from flotation
    • Feed density acceptable in a wide range, normally up to 45 percent solids by weight

    Wet LIMS – Dense media recovery DM and DMHG

    • Very long magnetics pick up zone
    • Standard and High Gradient (HG) magnetic systems available
    • For low to high Fe grade feed
    • Concurrent operation with long magnetics pick-up zone
    • Bottom spigots combined with effluent weir overflow for tailings flow control
    • Coarse particle tolerant, normally up to 8 mm
    • Used in both primary and secondary stages in single stage units

    Wet LIMS – Concurrent (CC)

    Wet LIMS – Counterrotation CR and CRHG

    Wet LIMS – Countercurrent CTC and CTCHG

    Wet LIMS – Counter rotation froth DWHG

    Wet LIMS – Dense media DM and DMHG

    Thanks for Metso