About magnet pulley / belt conveyor -14

To remove irons during conveying with a belt conveyor, there is a method that magnet pulley (roller) which is a kind of head pulley at the front edge of the conveyor and whose outside surface is covered by magnet to be attached.
It is used when metals need to be removed from staffs being conveyed. Only object made by metal sticks to the magnet head pulley via conveyor belt, so that only the metal staff are removed. This is often used in recycling plants, food plants, etc..
Objects being conveyed normally fall to chute, however, object made of metals are curried to return side of the belt without falling because of the magnet. Metals curried to return side finally falls where the magnetic attractive force becomes to have no effect. It can be said that magnet pulley is one of the cheapest and simplest magnetic screening facilities since screening can be took place with only replacement of head pulley to magnetic pulley.
However, this is not perfect. Objects being carried with belt conveyer has thickness, therefore, upper part of objects which is far from the magnet might pass though without being stick to magnet and without being screened, although magnet has effect on bottom side which is near belt surface.
Therefore, other types of magnetic screening facilities are often used together.
Magnetic strength of the magnet pulley is normally around 2,000 gauss for vertical and 1,000 gauss for horizontal, however, there are stronger type with 3,000 gauss for vertical and 5,000  for horizontal as well.

The following movie is about belt conveyor type magnetic separator of empty cans. Magnet pulley is used as head pulley.
Empty cans are being separated into ones made of steel and ones made of aluminum.