US2826302A - Magnetic separator - Google Patents

Description

March 11, 1958 w. J. scoTT MAGNETIC SEPARATOR Filed Feb. 21, 1956 mmvrox WALTER J. sc TT FIG] @ZM MM A TTOPNEVS United States Patent O a 2,826,302 p MAGNETIC SEPARATOR Walter J. Scott, Porfland, Oreg. Application February 21, 1956, Serial No. 566,822

' 1 Claim. (Cl. 209-218) This invention relates to a magnetic separator, and more particularly to a device which will more effectively separate particles of magnetic material from particles of nonmagnetic material.

The present invention constitutes an improvement over the device shown and described in my prior Patent No. 2,604,207, granted July 22, 1952. The device of such prior patent is particularly effective for separating finely divided magnetic material from finely divided nonmagnetic material when such materials are settling in a liquid, such as water. By carrying out the separation in water or other liquid, a relatively long time of treatment of the material may be obtained in a limited space so that a relatively weak magnetic field in such space will provide effective separation. In the apparatus of the present invention, however, means are provided for projecting or extending the magnetic field into the separating space so as to intensify such field in the separating space. This is accomplished by disposing magnetic flux carrying elements substantially throughout the separating space. Effective separation is produced even when the material being separated falls rapidly through a separating space which is filled with air or other gas. The apparatus of the present invention is therefore capable of carrying out efficient magnetic separation where the separation is carried out in a liquid, such as water, or is carried out in a gas-filled separating space.

In the apparatus of the present invention, a plurality of spaced elongated magnetic elements having high mag netic permeability and low magnetic retentivity are carried through a separating space in such a manner that portions of the elements pass close to, or are in contact with, the pole faces of a plurality of magnets which may be either permanent or electromagnets. The remaining portions of such magnetic elements extend into and at least partly across the separating space so as to come into contact with or be positioned closely adjacent the particles of the materials being separated. The magnetic elements referred to are carried out of the separating space while their first mentioned portions are still in contact with, or close to, the pole faces of the magnets so that such members carry magnetic material adhering thereto out of the separating space and away from the nonmagnetic material passing through such space. When such magnetic material has been thus carried out of the separating space, the magnetic elements are removed from the vicinity of the magnets so that the magnetic material carried by the magnetic elements is released and discharged separately from the nonmagnetic material. Since the magnetic elements have low magnetic retentivity, substantially all of the magnetic material is released from the magnetic elements. The magnetic elements are thereafter again brought into the vicinity of the magnets so as to be again magnetized and passed through the separating space. 1 i

' The specific apparatus disclosed in the present applilarged scale through a portion of the flexible carrier of- 2,826,302 Patented Mar. 11,1958

form of spaced fingers of magnetic material extending substantially perpendicularly from the surface of an endless carrier of nonmagnetic material, such as a belt, the magnetic fingers being carried upwardly along a vertical separating run of the belt through a separating space into which material to be separated is introduced and allowed to pass downwardly therethrough. The material being separated is brought into close proximity to such fingers of magnetic material while an end of each of such fingers is in close proximity to the face of the pole of a magnet. The fingers become magnetized and magnetic material adheres thereto, the nonmagmatic material passing downwardly and through the separating space. The magnetic fingers are carried out of the separating space while their ends are still maintained close to the poles of magnets and they are thereafter removed from the vicinity of the poles of magnets. Since the fingers are made of magnetic material having low retentivity, they immediately lose substantially all of their magnetism and the magnetic material carried thereby readily separates from the fingers and is discharged separately from the nonmagnetic material.

It is therefore an object of the invention to provide an improved magnetic separator which will more effectively separate particles or pieces of magnetic material from particles or pieces of nonmagnetic material.

A further object of the invention is to provide a magnetic separator in which elements of magnetic material having high permeability and low retentivity are passed through a separating space while surrounded by a magnetic field produced by magnetism induced in such ele ments from magnets adjacent a portion of such members and the magnetic elements are thereafter removed from the vicinity of such magnets after they have carried magnetic material out of the separating space.

Another object of the invention is to provide an improved magnetic separator which efiectively separates magnetic materials from nonmagnetic materials and which can be employed to separate such materials while they are moving downwardly through a separating space filled either with a liquid or with air or other gases.

A further object of the invention is to provide a magnetic separator in which magnetic elements of high permeability and low retentivity have magnetism induced therein from permanent magnets while being passed through a separating space in close proximity to material to be separated into magnetic and nonmagnetic portions and in which the magnetic elements carry magnetic material out of the separating space and thereafter have their induced magnetism removed so as to release and enable discharge of the magnetic material separate from the nonmagnetic material.

Other objects and advantages of the invention will ap-' pear in the following description of a preferred embodiment of the invention shown in the attacheddrawings of which: I

Fig. 1 is a vertical section through an apparatus in.

accordance with the present invention, taken on the line Fig. 3 is a fragmentary view showing a portion of the.

flexible carrier, magnetic fingers and magnetic rails of the present invention in front elevation;

Fig. 4 is a fragmentary horizontal section on an en Fig. 3;

tiaticu'includes a plurality of magnetic elements in the Fig. 5 is a view similar to Fig. 4 showing a modified.

manner of attaching the magnetic fingers to the flexible carrier;

Fig. 6 is a view similar to Fig. 5 showing a further modification of magnetic fingers and carrier therefor; and

Fig. 7 is a fragmentary front elevation of the modification of Fig. 6.

Referring more particularly to the drawings, the magnetic separator of the present invention may include a.

casing '10 in which is journaled upper and lower shafts 12 and 14, respectively. The shafts 12 and 14 extend laterally through the casing and arepreferablyin vertical alignment. Each of the shafts 12 and 14 has a pair of spaced belt wheels or drums 16 secured thereto adjacent the sides of the casing 10. A flexible belt or carrier 18 is trained over the drum 16 and also over a pair of drums 20 secured to a shaft 22 also journaled in the sides of the casing and positioned rearwardly'of the shaft 12. The belt 18 is also trained over a pair of drums 24 secured to a shaft 26 journaled-in the sides of the casing 10 and positioned between and below the shafts 1-2 and 22. The positions of the various shafts in drums, above described, are such that the flexible carrier 18 has an upward run 28 adjacent the front of the casing 10 but spaced therefrom, a horizontal upper run 30 and a return run 32 between the drums 20 and 16 by way of the drums 24.

The front portion of the casing 10 and the vertical run 28 of the carrier 18 define a separating chamber 34. Material to be separated may be introduced into an upper hopper portion 35 of the casing 10, such hopper portion delivering such material into the separating chamber 34. The material introduced into chamber 34 for separation will, in general, either be in powdered or granular form, although material having particles or pieces of substantial size may be separated so long as the particles or pieces of magnetic material are discrete particles capable of being separated from the particles of nonmagnetic material. The material to be separated may either be introduced in a liquid or may be separated in a dry condition during its movement downwardly through the separating chamber 34.

The belt or carrier 18 has a plurality of magnetic elem ments or fingers 36 projecting substantially perpendicularly from its outer surface, such fingers being distributed over such outer surface of the carrier and being of a magnetic material having a high permeability and low retentivity, for example, the magnetic material may be a high grade of transformer iron. The fingers 36 may be secured to the belt in various ways, one manner being illustrated in Fig. 4, in which each of the fingers are made up of two pieces of thin magnetic material riveted together and having their ends 38 bent in opposite directions and secured between two layers 40 and 42 making up the belt 18.

The ends of the fingers 36, which are secured in the belt 18, are carried by the belt in close proximity to members of magnetic material in the form of rails 44 and 46 positioned between the drum 16 and in engagement with the vertical front run 28 of the belt 18. As shown in Fig. 2, the rails 44 and 46 are spaced laterally from each other and, as shown in Fig. l, are curved at their lower and upper ends so as to conform to the curvature of the belt 18 in passing around the drums 16 Preferably, a portion of each of the rails 44 and 46 extend horizontally below the upper run 30 of the belt 18. A plurality of permanent magnets 48 are positioned to have their poles in contact with the magnetic rails 44 and 46 and such permanent magnets are supported by a backing member 50 in turn supported by cross members 52 secured to the side of the casing 10. The permanent magnets 48 extend between the magnetic rails 44 and 46 and are arranged such that the rails are of opposite polarity. For example, all of the north poles of the magnets 48 may be in contact with the rail 44 and all of the south poles of the magnet may be in contact with the rail 46. The rails 44, and 46 are also preferably made of magnetic material having high permeability and since the magnetic fingers 36 are carried in close proximity to the rails 48 or in contact therewith 4 by belt or carrier 18, the fingers 36 become magnetized and the separating chamber 34 is permeated substantially throughout with a magnetic field. Permanent magnets of high strength are commercially available and may be made of any one of several known or suitable alloys, one such alloy being of aluminum, nickel and cobalt. It will be, of course, apparent that electromagnets may be substituted for the permanent magnets 48 but, in

- many cases, a greater magnetic effect in a given space can be produced by modern permanent magnets than by electromagnets.

Either, or both, of the shafts 12 or 14 may be driven from any suitable source of power, for example, by a pulley 54 on the shaft 14 in a direction to cause the vertical front run '28 of the belt 18 to advance upwardly at a controlled rate of speed so as to carry the fingers 36 upwardly. Material to be separated is introduced into the separating chamber 34 through the hopper and progresses downwardly therethrough in close proximity tolthe fingers 36 which, as-shown in Fig. 3, are preferably distributed in staggered relation on the carrier. A plurality of downwardly inclined baifies 55 are preferably positioned adjacent the fingers 36 to direct the material being separated into contact with the fingers. Magnetic material adheres to the fingers and is carried upwardly and then laterally along the upper run 30 of the belt 18. Nonmagnetic material continues downwardly through the separating chamber 34 and is discharged from the lower end thereof under control of an adjustable gate 56. As soon as the fingers 36 pass to the left in Fig. 1, past the end of the magnetic rails 44 and 46, they become rapidly demagnetized such that magnetic material adhering to the fingers drops therefrom and upon passage of the belt around the drums, suchrnaterial is discharged to a hopper 57. The fingers are then carried by the belt 18 aroundthe drums 24 which have sufiicient radius of curvature that theends of the fingers 36 do not interfere and the fingers are then carried downwardly and around the lower belt 16 and again upwardly through separating chamber in proximity to the magnetic rails 44 and 46 and to the material to be separated.

The magnetic elements or fingers may take various forms and a modified form is shown in- Fig. 5 in which the magnetic elements 58 are made up of U-shaped members of magnetic material riveted together and then riveted to a modified form of carrier 69 so that the portions which connect their extending portions are in close proximity to the magnetic rails 44 and 46.

In the structure shown in Figs. 4 and 5, all of the magnetic elements or fingers on one side of a median line extending longitudinally of the belt have magnetism induced from magnetic poles of one polarity and the fingers on the other side of such median line have magnetisrn induced from poles of opposite polarity. A somewhat better distribution of magnetic flux in the separating chamber may be produced if alternate rows of fingers extending substantially across the belt are of opposite polarity and such distribution of the fingers can 'be' accomplished by the structure shown in Figs. 6 and 7. In these figures, Z-shaped bars 62 of magnetic material which carry fingers 64 and 66 also of magnetic material are secured to the carrier 60. The Z-shaped bars have one of their legs secured to one side of the belt 68 and their other legs spaced from the other side of the belt 68. The alternate bars have opposite ends secured to the belt and with such structure, a portion of each of alternate bars 62 are adjacent one of the magnetic rails 44 and a portion of each of the other alternate bars 62 are adjacent the magnetic rail 46. Such Z-shaped bars have other portions extending laterally of the carrier 60 and are spaced from the magnetic rails 44 or 46. The structure is such that alternate bars 62 and the fingers 64 and 66' carried thereby are of opposite polarity. A

substantial amount of magnetic flux extends between that the magnetic field is more evenly distributed throughout the separating space and greater magnetic forces are present tending to hold magnetic materials in the form of particles or small pieces on the various fingers 64 and 66. The bars 62 and the fingers 64 and 66 are preferably of magnetic material having high permeability and low retentivity and it will be apparent that the magnetic structures of Figs. 6 and 7 may be substituted for that shown in Figs. 1 to 3. It will also be apparent that a greater number of magnetic rails than two can be employed with alternate rails of opposite polarity.

I claim:

Apparatus for effecting separation of particles of magnetic material from particles of nonmagnetic material, which comprises a casing providing a separating chamber for receiving particles of the material to be separated, means for feeding said particles into the top of said chamber and discharging particles from the bottom of said chamber, an endless carrier having a vertical run adjacent one side of said chamber, a plurality of elongated elements of magnetic material of high magnetic permeability secured to said carrier at one end and extending into said chamber, providing magnetic fingers spaced longitudinally and laterally of said run, a plurality of downwardly inclined stationary baffies mounted adjacent the other side of said chamber and extending toward said elements to direct particles toward said element,

magnetic rail members providing magnetic poles extending longitudinally of said run and in close proximity to said ends of said elements to magnetize said elements by induced magnetism, a plurality of permanent magnets extending between said rail members to induce magnetism into said rail members, means supporting and moving said carrier to move said elements longitudinally of said run through and out of said chamber so that particles of magnetic material adhere to said elements and are carried out of said chamber, said carrier having a portion spaced from said chamber and from said members and said elements having low magnetic retentivity so as to release said particles of magnetic material when said elements are carried away from said members, and means to discharge the released particles of magnetic material separately from particles of nonmagnetic material.

References Cited in the file of this patent UNITED STATES PATENTS France Mar. 10, 1930

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