Magnetic Separation is one of the physical concentration processes that utilizes the
differences in magnetic properties of various minerals present in the ore body.

The magnetic fraction may be valuable or gangue depending upon its end use in a particular
process and so also the non-magnetic fraction, e.g., separation of magnetite (magnetic)
from quartz (non-magnetic), separation of tin bearing mineral cassiterite (non-magnetic)
from magnetite (magnetic) impurity etc.

The magnetic force in a magnetic field is generally conceived and represented by
magnetic force lines. For a magnet they are envisaged as running from the south pole to
the north pole.

In its field magnet always exert some force on the body placed there. That
force may be attractive or repulsive depending on the properties of the placed body.
When a body is placed in a magnetic field,

the magnetic line may be concentrated inside the body and the body is pushed towards the higher field intensity or the force line may be expel from the placed body and as a result the body pushed towards the lower field
intensity. Depending on this material may be categorized in to two major groups namely
paramagnetic material (as in the first case) and diamagnetic material (second case).

There are some material which shows special kind of paramagnetism called ferromagnetic
material. They have very strong attractive force in the magnetic field. These behaviors of
material in magnetic field are utilized in magnetic separation.

It is observed that the
diamagnetic force is too weak and in practical purpose it can not he utilized for
separation. Paramagnetic force is strong enough and is used industrially for magnetic
separation.

COMMON TYPES OF MAGNETIC SEPARATORS USED FOR

Ore Cobbing Magnetic Pulleys

Ore cobbing or concentrating magnetic pulleys utilize more poles across the pulley width
so as to develop as uniform field depth as possible and a sufficient area of collecting
magnetic poles to carry the large amount of magnetic material commonly encountered in
such applications. Generally, ferromagnetic minerals are used for concentration.

Magnetic Drums

Magnetic drums with axial pole design are used to concentrate ferromagnetic minerals.
Feed materials up to 1-inch diameter can be treated. The drum speed can be varied
between 20-45 rpm in low intensity whereas it is up to 200 rpm for high intensity separators.

Induced Roll Magnetic Separator

It develops high intensity magnetic fields and is capable of removing particles that do not
respond to the low intensity magnetic separator. This is widely used to treat beach sands,
wolfratnite, tin ores, glass sands and phosphate rocks.

Cross-belt High Intensity Magnetic Separators

A cross belt runs across the face of the electromagnetic pole, and the sharp magnetized
points of this upper pole attract the weakly magnetic material. The cross belt transports it
to a suitable discharge point. Selective mineral concentration of weakly magnetic
minerals can be performed by using this instrument.

Ring Type Magnetic Separators

The basic construction is similar to the cross belt but a magnetized steel ring is
substituted for the cross belt.