US3389794A - Magnetic separator - Google Patents

Description

June 25, 1968 SABURO MIYATA 3,389,794

MAGNETIC SEPARATOR Filed April 12, 1965 4 Sheets-Sheet 1 \\\\\\|m\\\ |&\\\\\\ ///////4 33 v F 1G. 1.

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June 25, 1968 SABURO MIYATA Filed April 12, 1965 4 Sheets-Sheet 2 INVENTOE SABURO MIYATA BY MAGNETIC SEPARATOR J ne 25, 1968 SABURO MIYATA MAGNET IC SEPARATOR 4 Sheets-Sheet 5 Filed April 12, 1965 FIG. 9.

FlCl'f INVENTOR. 5 5. N SABURO MIYATA United States Patent 3,389,794 MAGNETIC SEPARATOR Sabin-o Miyata, 58 Shimo Takanawa, Minato-ku, Yokohama, Japan Filed Apr. 12, 1965, Ser. No. 447,189 3 Claims. (Cl. 209219) ABSTRACT OF THE DISCLOSURE The invention comprises a magnetic filter taking here two forms. First there is a pulley having a non magnetic surface layer, within which is a magnet system comprising a plurality of magnetic discs, pairs of which are spaced by magnetizable mild steel discs of slightly greater diameter than the magnetic discs. The steel discs are rabbeted to receive rings of non magnetic material over the niagnet'discs. By this means, areas of concentrated flux density are provided on the surface at the peripheries of the pole pieces. End pole pieces similar to the intermediate pole pieces are provided each having but one rabbet. In another form the magnets are bars and they are separated by pole pieces over which strips of non magnetic material are placed. A sheet of non magnetic material is above and below the assembly of bars.

This invention relates to an apparatus for removal of ferromagnetic material from fluent material. More particularly the invention relates to means for removing ferromagnetic particles from liquids or particulate masses which are capable of flowing or moving by gravity from a higher level to a lower level when restraint is removed. This conception is believed to conform to the dictionary definition of fiuent as easily moving.

In practicing the invention, fluids or liquids sometimes normally static may be caused to flow over or under the apparatus of this invention for removing ferromagnetic particles from such fluids. Also, masses of particulate material which may contain ferromagnetic particles may be moved over or under or by the apparatus of this invention for removing such ferromagnetic particles.

An object of this invention is the provision of a magnet device for attracting ferromagnetic particles which produces a high flux density at a surface engaged by the fluent material.

A second object of this invention is the provision of a magnet device composed of a plurality of ferrite magnets having a thickness along their polar axes that is less than the face dimensions perpendicular to such axes.

A third object of this invention is the production of a magnetic device having a plurality of very thin magnets, magnetized in the direction of their smallest dimension, arranged with like poles facing and separated by pole pieces of paramagnetic material.

A fourth object of this invention is to provide a magnetic device having a surface divided into a plurality of alternate N and S poles to thereby create areas on said surface of intense magnetic flux between such poles.

It is known that some ferrites, such as barium ferrite, BaO6Fe O when sintered and formed into suitable shapes can be magnetized to produce powerful magnets. They can be selectively magnetized, i.e., on any desired axis. Thus, Wafer magnets, having a thickness much less than any other dimension, can be produced, and they can be magnetized in the direction of their thickness. The magnetic apparatus of this invention is built around the last noted property of ferrite magnets.

Other objects and advantages of this invention will become apparent from a consideration of the following specification taken with the annexed drawings, which together form a complete disclosure of the invention.

3,389,794 Patented June 25, 1968 "ice In the drawings:

FIG. 1 is a vertical section through one form of the invention;

FIG. 2 is a sectional view substantially along the line 22 of FIG. 1;

FIG. 3 is a diagrammatic view of one manner of using the device of FIGS. 1 and 2;

FIG. 4 is a diagrammatic view of a second manner of practicing the invention;

FIG. 5 is a diagrammatic view of a third manner of practicing the invention;

FIG. 6 is a fragmentary vertical section similar to FIG. 1 showing a modified form of drum;

FIG. 7 is a face view of a spacer;

FIG. 8 is an axial section of FIG. 7;

FIG. 9 is a fragmentary side view, with parts in sectic-n, of a type of magnet array used in FIG. 6;

FIG. 10 is an axial section of the device of FIG. 9;

F I6. 11 is a fragmentary axonometric view of a modified form of the apparatus;

FIG. 12 is a fragmentary axonometric view on a larger scale;

FIG. 13 is a fragmentary axonometric view of a device according to this invention employing the magnets of FIGS. 6 and 7; and

FIG. 14 is a diagrammatic view of a screening device using the magnetic apparatus of FIG. 8.

Referring now to the drawings wherein like parts are represented by like characters of reference throughout the several figures, and particularly to FIGS. 1 and 2; number 10 indicates a drum of relatively large diameter. The drum 10 has a peripheral surface 11 and end walls 12 and 13, all of which may be formed of non-magnetic material such as non-ferrous metals or suitable plastics. A shaft 13, which may be solid, as shown, or tubular is located in the axis of the drum 10. The shaft 13 may be formed of non-ferrous metal or suitable plastic. As shown, the shaft 14 is threaded at either end as at 15, and is provided with nuts 16 which function in a manner later to be noted.

The drum 10 will obviously be made to any suitable diameter and axial length. Between the end plates 12 and 13 I provide my novel magnet assembly including a plurality of disc-like magnet arrays 17, each comprising a plurality of annularly arranged substantially wedge- shaped wafer magnets 18, 19 and 20 of increasing cross section from the center out. The magnets 18 are spaced apart slightly, in a circumferential direction, as at 21, and form a broken disc or annulus. The magnets 18 may be united through the interspaces 21 by means of suitable cement such as epoxy resin glue. However, the interspaces 21 may be air gaps and the assembly of magnets may be secure-d in their annular arrangement by means later to be described.

The magnets 19 and 20 form two concentric annuli, each concentric with the annulus formed by the magnets 18. Their respective interspaces 22 and 23 may be as provided for the magnets 18. The annulus 24 is formed of the magnets 18 and is spaced from the annulus 26, formed of the magnets 19, by the annular space 27. The annulus 26 is spaced from the annulus 28 by like annular space 29. The spaces 27 and 29 may be filled with a cement such as an epoxy resin glue or they may be treated as later to be noted.

A plurality of pole pieces 30 are placed in the assembly, one between each pair of magnetic arrays 17 and one at either end of the assembly. These pole pieces are of mild steel and are of a thickness less than the thickness of two magnet arrays 17. As described, the magnets 18, 19 and 20 are substantially wedge-shaped or keystone-shaped wafers, and are preferably formed of a suitable ferrite as mentioned above. These magnets are magnetized in the direction of their thicknesses, and therefore have, each, one face as a N pole and one face as a S pole. The magnets of the arrays 17 are arranged with common-like poles in a plane and alternate arrays 17 have like poles facing. While it may be desirable to assemble the magnet arrays 17, as previously described, it is desirable also to assemble them on or between pole pieces 30 by the use of suitable adhesives, such as epoxy resins.

The magnet arrays 17 are preferably of a diameter slightly smaller than that of the pole pieces 30 and the diameter of the arrays 17 is made the same as that of the pole pieces 30 by adding a ring of non-magnetic material 31. The ring 31 is preferably of greater axial dimension than the thickness of the magnet wafers 20, and as a consequence the pole pieces 30 are circumferentially rabbeted as at 32 to leave a very thin pole piece 33.

While the sleeve or shell 11 is shown, and in some instances will be preferred, it is to be noted that if the shell 11 were omitted and the peripheral surfaces of the rings 31 and the pole pieces 30 were finished smooth, a greater magnetic elfect will be produced. It is therefore contemplated that, under some circumstances, the shell 11 may be omitted. The drum is formed by assembling a suitable number of magnetic arrays 17 as described, and spacer pole pieces 30, with two end pole pieces 30, on a shaft 14 and using end plates 12, 13, with or without the sleeve 11 cut to suitable axial dimensions. Nuts 16 are threaded on the threaded portions of the shaft 14 and tightened to clamp the assembly into a substantially rigid unit or drum magnet 10. The arrangement is such that a strong concentrated area of magnetic flux is present at the periphery of the drum in the region between two N poles or two S poles. Since the wafer magnets 18, 19 and 20 are thin and the pole pieces are only slightly thicker, the areas of strong flux will attract any ferro-magnetic material that may come within their field of influence.

FIGS. 3, 4 and 5 illustrate diagrammatically some of the uses of the magnetic drum 10. In FIG. 3, a liquid 34 having suspended therein particles of ferromagnetic material 35 flows down a trough 36 onto the rotatably mounted drum 10. At about the point 37, approximately the vertical tangent point on the drum 10, the liquid 34 flows into the tank 38, from which it may be drained by means of the valved outlet 39. The particulate ferromagnetic material 35 clings to the drum surface and at about the vertical tangent point 40 it is removed by means of the doctor knife 41, or other suitable means, and is collected in the tank 42.

In FIG. 4, the rotatably mounted magnetic drum 10 dips in a suspension 43 containing dispersed ferromagnetic material 44. The suspension 43, is, in this case, in a compartment 45 formed by means of a partition 46 in the tank 47. The material 44 clips to the drum 10 and is removed by the doctor knife 48 and collects in the compartment 49. It is within the purview of this invention to form the compartments 45 and 49 as separate tanks, or receptacles.

In the embodiment shown in FIG. 5, .the rotatably mounted magnetic drum 10 receives a belt conveyor 50 which is passed about the drum 10. Particulate material 51 is carried by the conveyor 50, and may contain ferromagnetic particles 52. The particulate material 51 falls off the conveyor 50 and is collected in the receptacle 53. The ferromagnetic material 52 clings to the conveyor 50, by virtue of the intense flux areas on the drum 10, until carried beyond the influence of such fiux. It then falls into the receptacle 54.

In FIGS. 6 to 10 inclusive, I show a modified drum 110 having a shaft 114 and a shell 114 spaced from the drum 114 by means of one or more disc webs 114 A plurality of annular magnet arrays 117 are placed about the shell 114 Each array 117 comprises a plurality of annularly arranged magnets 119 and 120. The magnets 119 and 120 are substantially keystone-shaped and are closely spaced radially and circumferentially. Each magnet array has end or pole pieces plates of ferromagnetic material. The inner diameters of the spacers are slightly greater than that of the annular series of magnets 119, and the space between the pole pieces is filled with nonmagnetic material, which may be cement. The pole pieces 130 are of larger outer diameter than the adjacent annular series of magnets 120. The circumferential space between the pole pieces 130 is filled with non-magnetic material, which may be cement.

The magnets 119 and 120 are magnetized in the direction of their thickness as indicated by the letters N and S for the N and S poles, in FIGS. 6 and 10. As there is a strong tendency for the arrays 117 to separate due to facing like poles, it may be necessary to fix all the elements 119, 129, 130 and 130 in place with suitable cement, such as an epoxy resin. The pole pieces 130 and 130 are preferably of a thickness less than half that of the magnets 119 and 120, so that alternate pairs form very strong N and S poles to produce powerful flux rings along the outer surface of the drum 119. This drum will operate in all respects like the drum 10, and is particularly useful in the construction shown in FIG. 5.

In FIGS. 11, 12, 13 and 14, I illustrate a modification of the invention wherein I employ a magnetic apparatus 210 which may comprise a plurality of magnet arrays 217. The magnetic apparatus 210 generally comprises bottom and top plates 260 and 261 and end plates 262 and 263 and a plurality of magnet arrays 217 arranged side by side with spaces 227 and 229 between them. The spaces may be filled with suitable cement or the magnet arrays 217 may be cemented to the plates 260 and 261 by means of suitable adhesives. A magnet array 217 consists of a plurality of prismatic wafer magnets 218, of sintered ferrite, magnetized along their smallest dimension. The magnets 218 are arranged with their like poles facing and are spaced apart by narrow pole pieces 230. The magnets 218 are not so high as the pole pieces and the difference is made up by non-magnetic strips 231. The whole assembly of magnets 218, pole pieces 230 and strips 231 may be made unitary by means of suitable adhesives, such as epoxy resin glues. Suitable assemblies 217 may be placed on a sheet 260 and cemented thereto, and the end pieces 262 and 263 cemented to the ends of the assemblies 217 and to the sheet 262. For use a trough 236 is formed by suitably attaching side plates 264 and 265, and the sheet 261 as its bottom. End pieces 266 may be used in the formation of the assemblies 217.

For use, the trough 236 forms part of an inclined plane type feeder 265, which may b of known type, such as a shaker screen or a vibratory feeder. Fluent material 251 passing along the feeder 265, containing ferromagnetic particles, will drop off the end of the feeder onto a suitable conveyor or into a suitable receptacle. The ferromagnetic particles will remain on the sheet 261 on the bottom of the trough 236 and may be removed from time to time.

Having now described my invention in its preferred aspects, I desire it to be understood that various changes and modifications may be made within the skill of the art and the scope of the appended claims.

I claim:

1. A magnetic device for removing ferromagnetic particles from fluent material contacting such particles, said device comprising a surface having zones of strong magnetic flux, said surface being the periphery of a cylinder having a series of longitudinally spaced apart permanent magnets of like facing poles, each of said magnets being a solid having length, breadth and thickness, the last dimension being the least, said magnets being magnetized generally in the direction of the least dimension and being arranged with their faces of greatest surface areas in planes substantially normal to the said surface, each of said spaced apart magnets constituting magnet arrays lying in radial planes of such cylinder, said spacing means comprising steel disc pole pieces positioned intermediate pairs of discs, the outer diameter of the magnet arrays being less than the outer diameter of the pole pieces, said arrays comprising at least two concentric radially spaced annuli, each annulus comprising a plurality of circumferentially spaced magnets, and a shaft for rotatably mounting the cylinder, each of said magnet arrays extending from said shaft to the 10 periphery of said cylinder.

2. The structure as defined in claim 1 wherein the pole pieces are rabbeted at each peripheral edge to the diameter of the magnet array, and including rings of nonmagnetic material over the magnet arrays and in the rabbeted portions.

3. The structure as defined in claim 1 wherein the magnet arrays comprise keystone-shaped magnets closely juxtaposed both radially and circumferentially.

References Cited UNITED STATES PATENTS 262,790 8/1882 King 209-223 359,085 3/1887 Mansfield 209-222 X 468,540 2/1892 Cane 210222 X 986,389 3/1911 Herr 209217 X 2,678,729 5/1954 Spodig 209219 X 2,992,733 7/1961 Buus 209-219 2,992,736 7/1961 Buus 209223 FOREIGN PATENTS 840,102 7/1960 Great Britain.

OTHER REFERENCES A.P.C. application of Veglio, Ser. No. 345,246, pub. May 18, 1943.

HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner.

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