GB1602279A - Magnetic separation - Google Patents

Description

(54) IMPROVEMENTS IN MAGNETIC SEPARATION (71) We, BRITISH STEEL CORPORA TION, a Corporation incorporated and existing under the Iron and Steel Act 1967 whose principal office is at 33 Grosvenor Place, London, S.W.1, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to magnetic separation. It is particularly concerned with the separation of fragments of ferrous scrap from non-ferrous or composite scrap fragments.

In the processing of automobile and consumer durable scrap, hammer mills are widely used to shred the scrap into small fragments which is a more manageable material for handling purposes. Following fragmentation, magnetic separation may be employed to remove non-ferrous metals such as aluminium, zinc, lead, tin and cop per so as to produce a relatively clean ferrous scrap suitable to feeding to a steel furnace.

Tests on the ferrous scrap have indicated that copper is not removed to the same extent as other non-ferrous metals with the existing magnetic separation techniques. The majority of the copper contamination appears to be in the form of armature fragments and brass or copper composite pieces. This contamination can have very deleterious effects on the steel if it is used for certain qualities of steel.

According to one aspect of the present invention, a magnetic separator includes a continuous conveyor belt which is driven around a drum by drive means adapted to run the conveyor belt at a speed of at least 200 feet per minute, said drum containing a magnetic device which remains static relative to said conveyor belt and in use acts to attract ferromagnetic material towards the belt as it passes around the drum, said device comprising a plurality of magnet poles extending around the interior of the drum for substantially 1800, the uppermost pole being positioned at an angle of at least 15 to the vertical through the axis of the drum in the direction of belt travel.

With a maximum acute angle of 35 the drive means should be adapted to run the conveyor belt at a speed not exceeding 500 feet per minute.

A splitter plate may be located below the drum and spaced from the conveyor belt, which splitter plate assists in the separation of ferromagnetic material from other contaminants. The separator may include a feed shute positioned above the belt towards the end of the belt distant from the drum containing the magnetic device.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which is a schematic side elevation partly in section of a magnetic separator.

A horizontal conveyor belt 10 passes around two drums 11 and 12 respectively, each one at the extent of the belt travel.

The first drum 11 which the belt 10 passes over is driven by a drive motor (not shown) and appropriate gearing. The second drum 12 contains a static magnetic device, comprising a set of magnet poles 13 closely adjacent the drum surface. The poles 13 are arranged so that they extend around 1800 of the drum, commencing at a position inclined an an angle equal to 15 from the vertical in the direction of travel of belt 10. The direction of belt travel is shown by arrow 14 in the drawing.

The drum 11 is arranged to be driven so that the belt speed is approximately 250 feet per minute.

Metal fragments are fed to the uppermost.surface of belt 10 down a shute 15 which typically has a vibrating mechanism to ensure even feed of material. The fragments are carried along to drum 12 where the bars and copper composite fragments tend to be thrown off the end of the belt 10, whereas the ferromagnetic fragments are carried around the drum 12 past a splitter plate 16 by their attraction to the magnet poles 13.

The angular location of the magnet poles, and their commencement is quite critical for the separation purposes which are to be served. With a belt speed of 200 feet per minute the first magnet pole must be located at least 15 to the vertical, or otherwise the composite fragments will not be separated from the fully ferromagnetic fragments. With the maximum belt speed of 500 feet per minute the first magnet pole must be located not more than 35 to the vertical, or otherwise the ferromagnetic fragments will leave the belt 10 prior to the splitter plate 16, and therefore not be separated from the composite fragments and pieces of brass and copper.

WHAT WE CLAIM IS: - 1. A magnetic separator including a continuous conveyor belt which is driven around a drum by drive means adapted to run the conveyor belt at a speed of at least 200 feet per minute, said drum containing a magnetic device which remains static relative to said conveyor belt and in use acts to attract ferromagnetic material towards the belt as it passes around the drum, said device comprising a plurality of magnetic poles extending around the interior of the drum for substantially 1800, the uppermost pole being positioned at an angle of at least 15 to the vertical through the axis of the drum in the direction of belt travel.

2. A magnetic separator as claimed in claim 1 having an angle of 35" of the uppermost pole to the vertical through the axis of the drum and a conveyor belt speed of between 200 and 500 feet per minute.

3. A magnetic separator as claimed in any preceding claim including a splitter plate located below the drum and spaced from the conveyor belt, the splitter plate assisting in the separation of the ferromagnetic material from other contaminants.

4. A magnetic separaor as claimed in any preceding claim including a feed shute positioned above the belt towards the end of the belt distant from the drum containing the magnetic device.

5. A magnetic separator as hereinbefore described with reference to and as shown in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. poles, and their commencement is quite critical for the separation purposes which are to be served. With a belt speed of 200 feet per minute the first magnet pole must be located at least 15 to the vertical, or otherwise the composite fragments will not be separated from the fully ferromagnetic fragments. With the maximum belt speed of 500 feet per minute the first magnet pole must be located not more than 35 to the vertical, or otherwise the ferromagnetic fragments will leave the belt 10 prior to the splitter plate 16, and therefore not be separated from the composite fragments and pieces of brass and copper. WHAT WE CLAIM IS: -

1. A magnetic separator including a continuous conveyor belt which is driven around a drum by drive means adapted to run the conveyor belt at a speed of at least 200 feet per minute, said drum containing a magnetic device which remains static relative to said conveyor belt and in use acts to attract ferromagnetic material towards the belt as it passes around the drum, said device comprising a plurality of magnetic poles extending around the interior of the drum for substantially 1800, the uppermost pole being positioned at an angle of at least 15 to the vertical through the axis of the drum in the direction of belt travel.

2. A magnetic separator as claimed in claim 1 having an angle of 35" of the uppermost pole to the vertical through the axis of the drum and a conveyor belt speed of between 200 and 500 feet per minute.

3. A magnetic separator as claimed in any preceding claim including a splitter plate located below the drum and spaced from the conveyor belt, the splitter plate assisting in the separation of the ferromagnetic material from other contaminants.

4. A magnetic separaor as claimed in any preceding claim including a feed shute positioned above the belt towards the end of the belt distant from the drum containing the magnetic device.

5. A magnetic separator as hereinbefore described with reference to and as shown in the accompanying drawing.