GB2039796A

GB2039796A - Magnetic Separator

Info

Publication number: GB2039796A
Application number: GB8001152A
Authority: GB
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1979-01-13
Filing date: 1980-01-14
Publication date: 1980-08-20
Also published as: DE2901194A1; SE8000296L; ZA80173B; AU5454680A

Abstract

A magnetic separator comprises a drum (1) with a stationary magnet system arranged inside the drum (1), the drum (1) comprising a largely non- magnetic material and having a plurality of ferromagnetic conveying elements (2) associated with its surface. The conveying elements may be partially or wholly embedded in the drum. <IMAGE>

Description

SPECIFICATION Magnetic Separator The invention relates to a magnetic separator having a stationary magnetic system which is arranged inside a rotary drum, such as a superconducting magnetic system.

In magnetic drum separators with superconducting magnetic systems there is the problem that the material which may be magnetized and which is drawn to the surface of the drum in the effective region of the magnetic system is kept in the effective region of the magnetic system by the high magnetic field forces. Extreme difficulties are caused by transferring of the magnetizable material out of the magnetic field into the largely field-free area.

Blockages of material and consequently faults in operation result from the magnetizable material being kept back in the region bordering the largely field-free area.

In accordance with German Patent Application P 2832275.0 and in an effort to solve this problem use of conveyer means comprising a material of high magnetic susceptibility is suggested, the conveyor means providing the magnetizable material with a sufficient bonding force due to residual magnetization so that safe removal of the magnetizable fraction of material out of the effective region of the magnetic system may be guaranteed.

The invention seeks to further shape the magnetic conveyor elements with respect to their arrangement on the rotary drum and their shape with regard to optimum separation of the magnetizable fraction of material.

According to the invention there is provided a magnetic separator with stationary magnet system arranged inside a rotary drum, wherein the rotary drum comprises a largely non-magnetic material and has a plurality of ferromagnetic conveying elements associated with the drum surface.

The conveying elements may be mounted on the drum surface, beneath the drum surface but projecting therefrom or wholly beneath the drum surface.

Both uniform and irregular distribution of the ferromagnetic elements, may be used which in cooperation with a rotary drum comprising plastics, guarantee that no eddy currents are able to be formed which could brake movement of the rotary drum or could weaken its magnetic field by screening. The entire surface of the rotary drum may be covered by this distribution so that the entire drum surface takes part effectively in this separation process whereby, in the case of uniform distribution which is advantageous for example for manufacturing reasons, any desired systematic approach is conceivable. The ferromagnetic elements may be arranged partly above and partly below the surface but also completely beneath the surface-at a small spacing. A plastics rotary drum provides particularly simple possibilities for fixing because of its ease of manipulation as a material.Thus it contributes overall to a high degree of separation of the magnetic separator.

The conveying elements may be flat or curved discrete elements, preferably pyramidlike in shape having a polygonal or circular base in which the length of one base edge-as seen in a side projection-is between 0.5 mm and 10 mm, preferably 3 mm and in which the ratio of the amount of the length of the base edges and the height of the pyramids is a maximum of 1:3.

Pyramid-like elements which are arranged on the surface of the rotary drum at their base are effective field gradient producers because of their edges and points and contribute to a good separation.

The conveying elements may have a cylindrical, more particuiarly needle-like shape, the diameter of which is between 0.5 mm and 5 mm, preferably 3 mm and its length projecting out of the surface of the rotary drum is between 1 mm and 30 mm, whereby the ratio of the length projecting out of the rotary drum and the diameter of the element is at least 1.1.

Finally, the elements may be of any desired shape, have a volume of 1 mm3 to 3 mm3 and be arranged in the walls of the rotary drum at a small spacing beneath the surface. This kind of dimensioning or arrangement of the ferromagnetic elements has proved to be advantageous in practice.

The invention will now be described in greater detail, by way of example, with reference to the schematic drawings, in which: Fig. 1 shows needle-like elements which are fixed beneath the surface of a rotary drum of a magnetic separator in accordance with the invention; Fig. 2 shows pyramid-like elements which are fixed beneath the surface or on the surface of the rotary drum and Fig. 3 shows cylindrical elements which are arranged beneath the surface of the rotary drum.

In all of the Figures a part of the rotary drum of a magnetic separator, shown in section, is designated by reference numbered 1.

Fig. 1 shows needle-like elements 2, which are inserted into the walls of the rotary drum 1 and have a length projecting out of these walls of approximately 30 mm and a diameter of approximately 2 mm.

Fig. 2 shows pyramid-like elements 3, which are fixed on the surface, preferably by means of adhesion or being partially inlet into the walls. The pyramids have a square base with an edge length A of approximately 3 mm and a height B of approximately 2 mm. However pyramid-like elements having any desired base are also possible in which those with numerous edges are regarded as preferred embodiments.

Fig. 3. shows ferromagnetic elements 4 arranged beneath the surface of the rotary drum 1. The elements 4 are arranged insulated from each other close beneath the surface and are constructed as rod-like elements. Such an arrangement is advantageous if attack due to corrosion is to be feared with respect to the ferromagnetic elements. The elements 4 may also be constructed as a continuous uniform wire grating which must however be low in mass for limiting the eddy currents which arise and heating of the walls of the rotary drum.

Claims

1. A magnetic separator with a stationary magnet system arranged inside a rotary drum, wherein the rotary drum comprises a largely nonmagnetic material and has a pluraiity of ferromagnetic conveying elements associated with the drum surface.

2. A magnetic separator according to Claim 1, wherein the conveying elements are mounted beneath the surface of the drum and project therefrom.

3. A magnetic separator according to Claim 1, wherein the conveying elements are mounted on the surface of the drum.

4. A magnetic separator according to Claim 1, wherein the conveying elements are mounted entirely just beneath the surface of the drum.

5. A magnetic separator according to Claim 2 or 3, wherein the conveying elements are discrete pyramid-like in shape with a polygonal or circular base, in which the length of the base edge-as seen in a side projection-is 0.5 mm to 10 mm, and in which the ratio of the base edge length to the height of the pyramids maximum of 1:3.

6. A magnetic separator according to Claim 5, wherein the length of the base edge is 3 mm.

7. A magnetic separator according to Claim 1, or 2, wherein the conveying elements have a cylindrical,the diameter of which is between 0.5 mm and 5 mm, and its length projecting from the surface of the rotary drum is between 1 mm and 30 mm, in which the ratio between the length of the conveying elements projecting from the rotary drum and, of their diameter is at least 1:1.

8. A magnetic separator according to Claim 77 wherein the conveying elements are of needle like shape.

9. A magnetic separator according to Claim 7 or 8, wherein the diameter of the conveying elements is 3 mm.

10. A magnetic separator according to Claim 1 or 4, wherein the conveying elements have a voiume between 1 mm3 and 3 mm3 and are arranged in the wall of the rotary drum at a small spacing beneath its surface.

11. A magnetic separator according to Claim 1 or 4, wherein the conveying elements compose a wire grating, wire netting etc. of small mass and arranged at a small spacing beneath the surface of the rotary drum.

12. A magnetic separator substantially as described herein with reference to the drawings.