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Electromagnetic separator

The electromagnetic metal separator, used in car scrap yards, may become a very important industrial application of electromagnetic induction. A car sent for scrapping contains a large amount of metal that may be recycled. Until recently only the steel could be separated by simply passing the crushed scrap along a belt over a d.c. electromagnet (see Figure 1(a)). The ferrous metal was attracted and passed round under the magnetic roller while the rest of the scrap fell into a hopper. The remainder of the scrap contained plastic, rubber and a large amount of aluminium and it was this aluminium that it was desirable to separate.

This further separation can now be achieved as follows. The remaining scrap is passed along a belt over an a.c. electromagnet (see Figure 1(b)). This induces eddy currents in the aluminium metal scrap that is then repelled by the field and flies off sideways while the remaining non-metal scrap continues along the belt. A very high purity for the aluminium separated by this method has been claimed. It has also proved extremely effective for separating bottle tops from crushed glass bottle waste.

Construct a small-scale aluminium metal separator in the laboratory and test how effective it is.
(A mixture of old milk-bottle tops and small stones is suitable for the material.)

(See: Electromagnetic separator (Experiment 14))
© Keith Gibbs 2011