1.     MAGNETIC SEPARATION:

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet.

In mines where wolframite was mixed with cassiterite, such as South Crofty and East Pool mine in Cornwall, magnetic separation was used to separate the ores. At these mines a device called a Wetherill's Magnetic Separator (invented by John Price Wetherill, 1844–1906) was used.

In this machine the raw ore   after calcinations was fed onto a moving belt which passed underneath two pairs of electromagnets under which further belts ran at right angles to the feed belt. The first pair of electromagnets was weakly magnetised and served to draw off any iron ore present. The second pair were strongly magnetised and attracted the wolframite, which is weakly magnetic. These machines were capable of treating 10 tons of ore a day which is a lot of ore. It is used for Iron containing ores or magnetic ores.

http://en.wikipedia.org/wiki/Magnetic_separation