US2645348A - Apparatus for magnetic separation of materials - Google Patents

Description

July 14, 1953 R c, HQFF 2,645,348

APPARATUS FOR MAGNETIC SEPARATION OF MATERIALS Filed June 25, 1949 INVENTOR RON/ 1.0 C.HOFF

ATTORNEY Patented July 14, 1953 APPARATUS FOltMAGNETIC SEPARATION OF MATERIALS l Renal d0. Hoff, Erie, Pa., assignor to Eriez Manufacturing Company, Erie, Pa., a corporation of Pennsylvania Application June 25, 1949, Serial No. 101,432

14 Claims. 209-218) This invention relates generally to apparatus for the magnetic separation of materials and more particularly to the separation of non-magnetic materials from magnetic materials.

When the mixed materials to be separated contain a relatively high percentage of magnetizable material, for example, from five to ten or more per cent as compared to ordinary separation where the magnetizable particles are usually measured in parts per 1000, the magnetizable particles tend to be attracted to each other as well as toward and to the magnet. In the past, it has been the practice to pass such mixed materials over a drum type separator of the agitator type. In this drum type separator, a cylindrical shell is rotated around fixed magnets having alternating north and south poles around a portion of the circumference. The magnetic material being carried around the drum is caused to change polarity and a tumbling action results. This method depends upon the non-magnetic material falling away from the face of the drum by gravity and in wet separation processes, with the aid of a streamof water washing the surface of the drum in a direction opposed to its rotation.

This method has never been too successful particularly with materials in the dry state and with the finer non-magnetic materials since. 1

l. The finer non-magnetic particles tend to stick to the magnetic particles and to the surface of the drum and they become entrapped in the bunched strings of magnetic .particles which have been attracted to each other;

2. The mixed dry materials are usually introduced to the drum at the beginning of a top quadrant thereof and gravity tends to remix the nonmagnetic and magnetic materials until the horizontal center line of the drum is approached allowing only the lower quadrant of the drum for the non-magnetic material to fall free; and

3. It has never been possible to increase the separating efliciency of an agitator. drum to any degree by the use of centrifugal force acting upon the non-magnetic materials since a. Impingement of the material mixture on a rapidly revolving drum tends to throw the mixture away from the drum before it can become b.-Passing the magnetizable materials throug alternate poles of a magnet cause particles thereof to turn end over end and when the particles are standing on end, their attraction to the magnet is greatly decreased whereby centrifugal force at this time can readily throw it off. On wet separation, a considerable volume of water is required. p

It is, accordingly, an object of my invention to overcome the above and other defects in mag-.

netic separation devices of the drum type and it is more particularly an object of my invention to provide apparatus for magnetic separation of materials which is simple in construction, economical in cost, economical in manufacture, and efficient in operation.

Another object of my invention is to provide apparatus for magnetically separating finely divided materials utilizing a rotating magnetic member with successive stages of magnetic pole pieces of opposite polarity around the periphery thereof.

Another object of my invention isto provide an inclined bafiie between a material delivering device and a magnetic drum with a rotating field. 1 Another object of my invention is to, provide apparatus for separating materials magnetically before reaching the face of a magnetized pulley comprising a series of inclined baffles, thelbafiies being inclined at different vertical angles from a horizontal plane passing through the axis of the magnetic drum.

Another object of my invention is to provide a series of inclined bafiles in the path of materials to be separated and in magnetic fields of opposite polarity of a magnetic drum, in association with conveying bafiles or aprons for conveying the nonmagnetic material separated on the baiiles from the magnetic material to a point adjacent the pulley for further separation. 7 Another object of my invention is to provide a series of bafiles in a magnetic separating device between the delivery point of the material to be separated and a magnetic drum, the height of the baffles adjacent the drum being greater than those adjacent the delivery point.

Another object of my invention is to provide a series of inclined battles between a delivery point of material to be separatedand a magnetic drum and means for pulsating or vibrating the bafiles upon the rotation of the magnetic drum.

Other objects of my invention will become evident from the following detailed description, taken in conjunction with the accompanying drawing, in which The figure of the drawing shows a more or less diagrammatic side elevational view of my novel apparatus for magnetically separating material with the magnetic drum shown in cross section.

Referring now to the drawing, I show in the figure of the drawing a magnetic drum I having circumferentially spaced, U-shaped magnets 2. The pole faces of the magnets 2 are engaged with pole pieces or shoes 3 disposed in spaced relation around the periphery of the drum I. The magnets 2 are attached to the drum I by bolt and nut assemblies 6. It will be noted that by the use of three magnets symmetrically placed around the inner periphery of the drum. I, six, equally spaced magnetic poles 9 of alternate polarity are provided around the periphery thereof. The magnetic fields I produced by the poles 9 are weakest adjacent the points of juncture 8 and strongest toward the central portion thereof as is well known in practice. The drum I has a non-mag neticbelt Ill engageable therewith the belt I!) engaging any suitable power pulley for rotating the drum I:, preferably in a counterclockwise direction.

Associated with the drum I are a series? of baf to be separated to the central portion of the first bafile I2. I preferably utilize a conventional vibrating conveying trough in order to evenly distribute the material to be separated movable therein. The angle of inclination of the bafiles I3, and I4 increases successively from the delivery trough IE to the drum I as shown in the drawing, The balile I2 has the least, angle of inclination and it has depending flanges I9. The

magnetizable material is drawn over the top side of thebafile. I2 with'the. use of a comparatively small magnetic force provided by the magnets 2 in the drum, I. The non-magnetic material flows downwardly by gravity on the baffle I2 opposite to the direction. of movement of the magnetic material. onto a conveyingapron H which is attac-hed to the support plate I5 by means of brackets 22 and screw bolts23. The ends Zld of the.

apron 2| are flanged downwardly. The apron 2| is inclined in a direction opposite to the inclinae tion of the baffles I2, I3, and I4 so that the material flows. bygravity downwardly thereon in the general direction of the drum. I The battle.

I3 receives the material that moves. over the top of the baffle I2 and it hasv the upper end I3a thereof bent toa vertical position. After separation on balile I3, the material that passes over the top thereof engages the midpoint of baffle lei where i more direct impingement on the succeeding baffles. The upper ends I3c and Ma of the baflies l3 and I4 are bent to more thoroughly agitate the material passing thereover whereby the nonmagnetic material will be shaken loose from any bunched magnetizable particles. The baiile I4 has a right angled depending bafile portion 24.

. the. drum I. The apron 25 is secured tothe plate I5 by means of brackets 25 and'screw bolts 21. The end 28 of the apron 25 is bent upwardly at right angles to prevent non-magnetizable material from flowing toward the face of the belt I0 on the drum I and to thoroughly agitate any remaining magnetizable particles impinging thereon due to the strong attraction of the magnets 2 in the drum I. The lower end 29 of the apron 25 is flanged. downwardly at right angles to permit the free flow of non-magnetizable material therefrom. r 1

The support plate I5 has an aperture 3 I through which extends a support shaft 32; the diameter of the aperture being greater than the shaft 32 tov permit pulsating or vibratory movement of the support plate I5. An: armature 33 is supported on an arm 34 which extends angularly upwardly from the upper end of the plate I5 and is secured theretoby welding or any other suitable means. The armature, 3.3- is made of: magnetizable material so that as it tends to close. the magnetic circuit between the north and south poles 9: of the magnets 2, it is moved inwardly. Upon continued rotation of the drum I, the armature 33 moves to a weak field and the. spring 35 urges it further separation takes place. The upper end Me of the baflle I4 isbent to an inclined position away' from the drum I to minimize the amount of non-magnetic material carried thereover to the belt I0. surrounding the drum I. The bafiles I2, 13, and 14 are. preferably arranged so. that the material flowing thereon strikes approximately the midpoint thereof. The baffles. I2, I3, and [4 preferably have successively greater angles of inclination in order that the finer nonmagnetizable materials carried with the magnetizable materials over the bafIles I2 and I3 will be shaken from the. magnetizable material due to the outwardly. The armature 33:. is thus movedinwardly and outwardly upon pass-age. of each pair of poles 9 of the magnets 2; thereby causing pulsating movement of the support I5. The com- 'pression spring 35 is supported by a bracket 36 and it engages the lower side of the support plate I5 remote from the drum I to urge the armature 33 away from the drum I. The vibrating or pulsating movement of the baffles I2, I3, and I l permit the use of baffles with less inclination thereby providing better separation The vibrations of the baliles i2, I3, and I4 permit the use permitting the, magnetizable particles to be walked up-over the baiiles end. over end more easily, particularly on the more. remote bafile I2 when the field is not as strong.

In operation, the drum I is rotated by the belt Ill and material to be. separated is delivered to the first inclined baffle I2 at approximately the midpoint thereof by a conventional vibrating trough I6. The vibrating trough I5 agitates the material to be separated sov that it is evenly distributed therein. The magnetic fields I of the magnets 2v of the drum I act upon the magnetiza ble particles in the materials to be separated. when they reach a point near the end of the trough It in the preferable form of my magnetic separating device. The magnetizable particles tend to string or bunch together when they enter the. magnetic fields of opposite polarity produced by succeeding poles 9 of the magnets 2.. The magnetic fields of opposite polarity cause the magend over end inasmuch as the field of one polarity magnetically induces the string of magnetizable material causing the more distant end of the string tobe'attracted by the approaching pole of opposite polarity. This action repeats as the drum revolves causing the particles to walk end over end into the face of the drum. Bystringing together the magnetizable particles, the par ticles on the ends thereof have a greater amount of induced magnetism. When the material to be separated reachesthe midpoint of the pulsating inclined bafile I2, the non-magnetizable material gravitates downwardly on the baflle I2 to the inclined apron 2| whence it passes to the apron 25 and to a suitable container. The magnetizable material is drawn upwardly over the upper end of the bafiie I2, end over end, impinges on the second baiile I3 whereupon the magnetizable material moves upwardly thereon end over end and the non-magnetizable material carried with the magnetizable material is shaken loose by the impingement and agitation of the magnetizable particles drawn over the upper end Isa of the baffle I3 and gravitates downwardly on the baffle I3. Inasmuch as the baiiie I3 is in a stronger magnetic field than bafile I2 because it is closer to the drum I, the upper end I 341 of the baffle 13 is bentup- .wardly to a vertical position to increase the agitation of the magnetizable particles to shake loose the non-magnetizable particles therefrom. When the remaining material leaves the upper end I3a "of the baffle I3 and is drawn with increased force into the baffle I4, it is violently agitated by the impingement and non-magnetizable particles clinging to or held by magnetizable particles are i shaken loose and they gravitate downwardly on the baifie It! to the apron 24, the magnetizable imaterial moving end over end upwardly thereon clinging to or held thereby. The angle of inclination of the baffles I2, I3, and [4 increases progressively from the delivery chute It to the drum I to progressively decrease the angle of impingement and increase the agitation of the magnetizable particles to assure complete separation.

All of the separated non-magnetizable material gravitating from the baflies l2, I3, and I4 pass to the apron 2! whereby they are directed to a. point adjacent the drum I.

As it passes from the lower end of the apron M to the upper end of the apron 25 adjacent the drum l, the material is again subjected to the strong magnetic forces of the magnets 2 of the drum and any remaining magnetizable material is drawn upwardly, end over end, over the bent upper end 28 of the apron 25 and it is gathered on the belt I surrounding the drum I. The magnetic fields of opposite polarity produced by the opposite poles 9 of the magnets 2 passing the armature 33 causeit and connected plate I carrying baffles I2, I3, and I 4 to pulsate thereby causing the material to be agitated at all times so that it gravitates down the inclined bafiies I2, I3, and I4 and aprons 2| and continuously and the magnetizable par- 'ticles are agitated so that the baffles I2, I3, and I4 may have a lesser inclination thereby minimizing i 6 the amount of magnetizable material gravitating with the non-magnetizable material to the apron 2 I, The non-magnetizable material gravitates from the apron 2| to the apron 25 which passes the non-magnetizable material to a point remote from the drum I. The magnetizable material is gathered on the belt I0 surrounding the drum I and any remaining non-magnetizable material is thrown off therefrom by centrifugal force. The magnetizable material drops from the belt III when it reaches a point outside of the magnetic fields I of the magnets 2. 7

Any type of delivery trough may be used but I prefer to use avibratory type because it provides an even uniform flow which gives uniform results. Although I show the baiiies I2, I3, and I4 attached to one side of a plate [5, I show this for illustration only inasmuch as the hafiles may be supported by plates on both sides thereof or by any other suitable supporting means. My magnetic separating device will operate without the pulsation of the'support plate I5 althoughI prefer to pulsate the support plate and the bafiles I2, l3, and [4 to assure the eflicient flow of the materials with bafiies having a minimum inclination. The armature 33' may be utilized for pulsating any accessory equipment in conjunction with the magnetic drum I. i

I prefer to use more thanone inclined baffle although it will be evident that my device will operate with only one inclined battle. I also prefer to increase the inclination of the baffies as they become more distant from the delivery trough and as they move into the strongest field of magnetization of the drum I because only the more finely grained non-magnetic material usually reaches the second and third baflles and increased obstacles causing greater impingement frees a maximum amount of non-magnetizable material.

It will further be observed that the upper ends of each succeeding baflle from the delivery trough to thedrum is spaced upwardly from the preceding bafile and the upper end of the baffles nearest to the pulley are inclined vertically or away from increasing the agitation and the consequent throwing off of the non-magnetic materials.

The drum I has the magnetic pole pieces and air gap-running parallel to the shaft supporting it so that when the drum revolves in front of the material to be separated or adjacent thereto, it causes the magnetic particles to tumble end over end in a pulsating action as the north and south magnetic fields intermittently magnetize the magnetic material as the drum I rotates.

Itwill be evident from the foregoing description that I have provided a magnetic separating device for separating magnetizable materials and especially materials containing an appreciable amount of magnetizable material wherein the material is run from a vibrating trough over one or more inclined separating baffles interposed between the delivery chute and the face of a belt on a magnetic pulley or drum, the magnetic drum material which gravitates with the non-magnetizable material from the inclined battles between the delivery chute and the pulley, which also separates non-magnetizable material from the magnetizable material by centrifugal forceafter it "rotating member having magnets spaced around the inner periphery thereof and rotating therewith, said magnets having alternately progressive magnetic poles of opposite polarity around the outer periphery thereof, an inclined bafiie spaced laterally from said rotating member within the magnetic fields of said magnets therein,

and means for feeding the material to be separated onto the side of said inclined baiile in a direction towards th magnets of said rotating member, said baffle being inclined away and downwardly from said member whereby non-magnetic material is directed therefrom by gravitation and magnetic material is drawn over the top of said inclined balile towards the outer surface of said rotating member.

2. A magnetic separating device as set forth in claim 1 wherein a plurality of successively spaced inclined bailies are spaced laterally from said rotating member, the angle of inclination of each successive baffle beinggreater than the angle of inclination of the preceding bafiie in the direction of said rotating member.

3. In combination with a rotating member having magnets disposed around theperiphery thereof providing magnetic poles of opposite polarity alternately and progressively around the periphery thereof, a plurality of spaced inclined baiiles spaced laterally from said rotating member within the magnetic fields of said magnets, the angle of inclination of said bafiies being away from said rotating member, and means for directing material to be separated into said inclined bailles toward said rotating member whereby magnetizablematerial is attracted by the magnets in said rotating member over the top of said bafiies and non-magnetizable material gravitates downwardly on said inclined bafiies away from said rotating member. 7

4. In combination with a rotating member" as .set forth in claim 3 wherein the upperends of said bafiles adjacent said rotating member are inclined away from said rotating member.

5. In combination with a rotating member as set forth in claim 3 wherein support means are provided for said bafiies and an armature is mounted on said support means adjacent said rotating member for pulsating said baffles and baille support means.

6. In combination with a rotating member as set forth in claim 3 wherein an inclined apron is disposed below said baffles inclined toward said rotating member to convey material gravitating from said baiil-es to a point adjacent said magnetic rotating member whereby further separation of said material takes place.

7. In combination with a rotating member as set-forth in claim 6 wherein a second apron is spaced from the end of said first apron and inclined at an angle opposite thereto to direct non-magnetic material away from said rotating member.

alternate north and south magnetic poles, a plu- .rality of inclinedbaflles spaced laterally outwardly from said magnetic drum, said bafiles be- .ing inclined away from said drum, means for delivering material to be separated into the bafiie furtherest from said magnetic drum toward said rotating member, an apron disposed below said baffles inclined toward said rotating drum for directing the material gravitating therefrom towards said magnetic drum, and a second apron 1 spaced from end of said first mentioned apron to direct said material flowing from said first mentioned apron away from said magnetic drum.

9. In a magnetic separating device as set forth in claim 8 wherein the angle of inclination of each of said successive inclined bafiies is inclined at a greater angle than thepreceding successive baflle from said material delivery means to said magnetic drum.

10. In a magnetic separating device as set forth in claim 9 wherein said baflles are-disposed on a support member, and means are provided for vibrating said support member and baflies thereon.

11. In a magnetic separating device as set forth in claim 10 wherein the means for pulsating said support member and baffles comprises an arm secured to-said support member having an armature adjacent said magnetic drum and in the rotating magnetic fields thereof.

12. In a magnetic-separating device, incom bination, a rotating member having magnets disposed around the periphery thereof within said rotating member defining alternate magnetic poles of opposite polarity, a deflecting member in the magnetic fields of said magnets spaced a predetermined distance laterally outwardly from the outer surface of said rotating member for deflecting the flow of material attracted to said rotating member, and an armature connected to said deflecting member disposed adjacent said rotating member in the magnetic fields of said magnets for pulsating said deflecting member upon rotation of said rotating member. V

13. In a magnetic separating device, in combination, a pulleyhaving magnets of generally U-shape disposed around the inner periphery thereof with the legs thereof transversely aligned around the periphery of said pulley defining progressive magnetic fields of alternate polarity around theouterperiphery of said pulley; a nona magnetic belt trained on said pulley, a delivery chute for material to be separated having the delivery end thereof in said magnetic fields, an V V inclined baflie disposed between said chute and said pulley, said bafiie being inclined away from said pulley, and a second baffle inclined oppositely to the direction of said first bafile to direct material gravitating therefrom towards and adjacent to said belt on said pulley, said material being fed by said delivery chute into said inclined baffle in a direction leading to said pulley.

14. In a magnetic separating device, in combination, a rotatable member having magnets rated passing toward said rotatable member to Number Name 7 Date deflect the path of same, mounted on said sup 463,305 Hoffman Nov. 17, 1891 port member for said armature. 500,604 Payne Ju1y'4, 1893 RONALD C. HOFF. 634,356 Kreuser Oct. 3, 1899 5 946,394 Ohm Jan. 11, 1910 References Cited in the file of this patent 1 529 970 which Man 17' 1925 UNITED STATES PATENTS 1,693,033 Hope NOV. 27, 1928 Number Name Date 2,1 7,637 Sutton Jan. 16, 1940 411,899 Mofi'att Oct. 1, 1889 FOREIGN EN 443,044: Finney DEC. 16, 1890 Number Country D te 449,726 Ball 7, 1891 103,310 Austria, May 10, 1926

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