Magnetic separation
Encyclopedia
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
or with bismuth such as at the Shepherd and Murphy mine in Moina, Tasmania
, 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 calcination
was fed onto a moving belt which passed underneath two pairs of electromagnet
s 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.
It is also used in electromagnetic cranes that separates magnetic material from scraps.
In mines where wolframite
Wolframite
Wolframite WO4, is an iron manganese tungstate mineral that is the intermediate between ferberite and huebernite . Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with granitic intrusives...
was mixed with cassiterite
Cassiterite
Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem...
, such as South Crofty
South Crofty
South Crofty is a metalliferous Tin and Copper mine located in the village of Pool, Cornwall, England UK. An ancient mine, it has seen production for over 400 years, and extends almost two and a half miles across and down and has mined over 40 lodes. Evidence of mining activity in South Crofty has...
and East Pool mine
East Pool mine
East Pool mine , was a metalliferous mine in the Camborne and Redruth mining area, just east of the village of Pool in Cornwall, England. Worked from the early 18th century until 1945, first for copper and later tin, it was very profitable for much of its life...
in Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
or with bismuth such as at the Shepherd and Murphy mine in Moina, Tasmania
Moina, Tasmania
Moina is a town situated 45 km inland from Devonport on the north-west coast of Tasmania, Australia's island state. Moina was the site of a brief gold rush in the late nineteenth century and then one of the largest Wolfram and Bismuth mines in Tasmania...
, 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 calcination
Calcination
Calcination is a thermal treatment process applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials...
was fed onto a moving belt which passed underneath two pairs of electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
s 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.
It is also used in electromagnetic cranes that separates magnetic material from scraps.