US2702123A - Self-cleaning magnetic separator - Google Patents

Description

Feb. 15, 1955 s'. G. INJEsKl, .JR 2,702,123

A SELF-CLEANING MAGNETIC sEPARA'roR Filed Feb. 17, 1954 2 sheets-sneu 1Y dad/@wah ,4 7' To RA/EYS.

Feb. 15, 1955 s. G. lNJEsKl, JR 2,702,123

i SELF-CLEANING MAGNETIC`SEPARATOR Filed Feb. 17, 1954 2 Sheets-Sheet 2 5 g 6 @if 5 NSi) man;

SELF-CLEANING MAGNETIC sEPAnAToR l Stanley G. Inieski, Jr., Milwaukee, Wis., assignor to Dinge Magnetic Separator Co., Milwaukee,` Wis., a corporation of Wisconsin Application February 17, 1954, Serial No. 410,842

8 Claims. (Cl. 209-223) This invention relates generally to improvements in the art of magnetic separation, and relates more particularly to improvements in the construction and operation of separators for removing magnetic substances such as pieces of iron from bulk material such as sand used especially during molding and casting operations in foundries.

The primary object of my present invention is to provide various improvements in the construction of so-called self-cleaning magnetic separating installations whereby the operation and functioning thereof is made more flexible while the eflciency of such units is enhanced to a maximum.

It has long been customary in the foundry industry, to remove pieces of iron from molding and core sand in order to permit re-use of the sand, by subjecting an advancing layer of the sand to the influence of a rectangular electro-magnet having depending central and opposite end poles coacting with the lower stretch or run of an endless conveyor belt travelling in proximity to and above the bulk sand layer. These prior separating units are either of the cross-belt type wherein the bulk layer is advanced transversely beneath the belt run, or of the in-line type in which the bulk mixture is fed and travels in the same direction as that of the lower belt stretch. ln both of these types of separators, the medial pole of the main magnet is positive whereas the two end poles are negative and the zones of negative polarity and influence extend considerable distances along the magnetic material transporting belt away from the main magnet. This arrangement of parts is sometimes detrimental when applied to the in-line type of installation since it frequently obstructs the self-cleaning characteristic of the unit by causing some of the magnetic pieces lor particles to either fail to be removed from the feed mixture, or to cling to the transfer run of the belt for too long a time, or to release these pieces from the belt stretch too soon so that they drop onto the sand discharge conveyor.

The present invention while perhaps also being` advantageously applicable to some extent to the cross-belt type of self-cleaning separators, is primarily applicable to the in-line type, and an important feature of the improvement is the provision of means for positively making such separating units self-cleaning while also insuring most effective removal of the iron from the sand.

. Another important object of the present invention is to provide a self-cleaning separator for positively and automatically removing magnetic material from a relatively thick advancing layer of foundry sand or the like, with utmost precision and under varying operating conditions.

A further important object of this invention is to provide simple instrumentalities for improving the functioning of in-line self-cleaning magnetic separators of the electro-magnet type, whereby most efficient separation of magnetic substances from non-magnetic burden is assured at all times.

Still another object of my invention is to provide a simple attachment which is readily applicable to the main electro-magnet of a self-cleaning separator of either the cross-belt or in-line type hereinabove referred to, in order to vary its functioning so as to meet diverse requirements.

These and other more specific objects of the present invention will be apparent from the following detailed description from which it may be noted that the gist of United States Patent O Patented Feb. 15, 195s the improvement is the provision of one or more auxhary energizing coils adapted to be associated with the main electro-magnet of a self-cleaning magnetic separator in order to vary the nature of the magnetic field of the main magnet so as to insure most effective separation of the magnetic material from the non-magnetic burden which is constantly presented to this field.

A clear conception of the features constituting the present invention, and of the construction and operation of numerous modified self-cleaning magnetic separators embodying the improvement, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a somewhat diagrammatic central longitudinal section through an in-line self-cleaning electromagnetic separator having a single auxiliary energizing coil associated therewith and also having endless belt conveyors for transporting the feed into the separating zone and for removing the separated ingredients therefrom, and showing the approximate functioning of the unit;

Fig. 2 is a similarly diagrammatic side elevation of an in-line self-cleaning separator having a pair of the auxiliary energizing and field modifying coils associated with the main magnet thereof but embodying reciprocable pan conveyors for introducing the feed and for removing the separated magnetic material;

Fig. 3 is a fragmentary and diagrammatic top view of a further modified in-line magnetic separator of the same type shown in Figs. 1 and 2, but embodying a single auxiliary field modifying pole and coil associated with he main electro-magnet to vary the functioning of the atter;

Fig. 4 is a longitudinal vertical section through an in-line magnetic separator of the type shown in Fig. 3 and taken along the line 4-4 thereof, the separator being provided with an auxiliary field modifying pole and energizing electric coil and with reciprocating pan conveyors for the feed and separated materials;

Fig. 5 is a similar section through an in-line magnetic separator such as depicted in Figs. 3 and 4, but embodying a pair of auxiliary field modifying poles and energizing coils disposed at opposite ends of the main electromagnet; and

Fig. 6 is a sectional view of a modified separating unit somewhat similar to that of Fig. 5, but showing a transverse magnetic material discharge conveyor and assemblage for altering the field of magnetic inuence.

While the drawings and description of the invention have been confined herein to in-line types of self-cleaning foundry sand and iron separators, some of the features may also be advantageously applied to so-called crossbelt separators and to devices for-handling other bulk materials; and it is also contemplated that specific descriptive terms employed herein be given the broadest possible interpretation consistent with the disclosure.

Referring to the drawings and especially to Fig. l, the in-line self-cleaning separator illustrated therein comprises in general, a main rectangular electro-magnet 8 having a central upright pole 9 surrounded by an energizing electric winding or coil 10 and also having opposite upright end poles 11, 12 spaced from the central pole 9; a main endless conveyor belt 13 coacting with pulleys 14, 15 journalled respectively in frames 16, 17 associated with the adjacent end poles 11, 12, and having a lower horizontal stretch or run 18 movable across and in close proximity beneath the main magnet poles 9, 11, 12; an auxiliary field modifying electric winding or coil 19 embracing the frame 16 associated with the main magnet end pole 11; an electric motor 20 for driving the pulley 15 and being mounted upon the frame 17; an auxiliary endless belt conveyor 21 for transporting the feed layer 22 into the field of magnetic uxor influence beneath the pulley 14 and in alinement with the lower run 18 of the main conveyor 13; another auxiliary endless sand discharge conveyor 23 disposed directly beneath and extending transversely of the main magnet 8; and still another auxiliary endless iron delivery conveyor 24 located beneath the pulley 15 and also extending transversely of the unit.

In all magnetic separators of this typeand whic utilize rectangular electro-magnets 8, the main conveyor belt 13 is formed of non-magnetic material; and when the magnet is energized by the coil. 10, the central pole 9 has positive or north polarity w hile the end poles 11, 12 have negative or south polarity thereby creating a zone or field of intense magnetic inuence along the lower surface of the belt stretch 18 directly adjacent'to these poles. Without the use of any field modifying coils 19 or the like, the pulleys 14, 15 of these prior self cleaning magnetic separators were ordinarily formed of magnetic steel while the pulley supporting frames 16, 17 were constructed of non-magnetic metal, s o that magnetic lines of force or ux of negative polarity were induced along the lower surface of the belt run 18 outwardly beyond each of the end poles 11, 12 of the main magnet 8 toward the adjacent peripheries of the pulleys 16, 17 respectively. In most installations such action was not desirable because these negative magnetic fields at both the pick-up and discharge zones for the magnetic material or pieces 25 repelled the latter and therefore failed to effect proper removal of iron from the nonmagnetic substance or sand 26 and from the conveying belt 13.

According to the present invention and as shown in Fig. 1, at least the pulley supporting frame 16 at the burden supply end of the separator, is formed of magnetic material such as mild steel, the same as the adjacent pulley 14, and the coil 19 which coacts with this frame 16 is energized to produce a positive or no rth pole zone adjacent to the lowermost peripheral portion of the pulley 14. This assemblage will therefore cause the iron material or pieces 25 to be more rapidly and positively withdrawn from the burden 22 onto the lower run 18 of the belt 13 and to cling to this belt run until these magnetic pieces have been transported across the sand discharge conveyor 23 and over the magnetic material delivery conveyor 24 where they are released from the belt run 18 and drop by gravity onto the transverse belt 24. The magnetic material 25 will thus positively prevented from dropping upon the sand discharge conveyor belt 23, thereby insuring most effective removal of the separated iron 25 and sand 26.

Referring more particularly to Fig. 2 of thedrawings, the in-line self-cleaning separator shown therein is similar to that shown in Fig. l, except that a reciprocating pan conveyor 27 is utilized for the feed burden 22; a similar r:onveyor 28 is employed for discharging the removed iron pieces 25; and another auxiliary magnet energizing coil 29 is provided at the iron delivery end of the assemblage. In this modification, the two pan conveyors 27, 28 are disposed beneath and in alinement with the lower stretch or run 18 of the main coriveyor, while the endless belt conveyor 23 extends across and beneath the main magnet 8, and the iron delivery pan conveyor 28 may be inclined as shown in dot-anddash lines. Both of the pulley supporting frames 16, 17

as well as the adjacent pulleys 14, 15 are formed of magnetic material so that energization of the two coils 19, 29 will produce positive or north pole zones at the lowermost peripheral portions ofV both pulleys. This modied structure will therefore create a stronger magnetic pick-up zone for initially withdrawing the iron material 25 from the sand 26, as well as providing a stronger magnetic material delivery zone as in Fig. 1.

Referring more specifically to the modified improved magnetic separator shown schematically in Figs. 3 and 4, this separator is somewhat similar to that shown in Fig. l, except that longitudinally reciprocable and alined pan conveyors 27, 28 are utilized for the feed burden and iron delivery respectively; a transverse pan conveyor 30 located between and beneath the adjacent ends of the conveyors 27, 28 is employed to discharge the sand; and the auxiliary energizing coil 19 coacts with a special magnetic pole 31 cooperating with the periphery of the adjacent magnetic pulley 14. In this embodiment the pulley support 16 is formed of non-magnetic material in order to prevent undesirable magnetic lines of force or ux from passing through the bearings for the pulley mounting shaft 34, and the pole 31 which may be attached to and supported by the main magnet 8 is of course constructed of highly magnetic metal. Wheuthe auxiliary coil 19 is energized, a zone of positive or' north polarity will be established adjacent to the lowermost peripheral portion of the pulley 15 at the feed zone as in the embodiment of the invention show n in Fig. 1, and the removed iron pieces 25 willbe positively withdrawn and held against the lower belt run 18 until they have been carried across the sand conveyor 30 and well within the pan conveyor 28, but the special pole 31 will function to confine the magnetic ux to the periphery of the pulley 14 as indicated by the arrows, thereby protecting the bearings for the shaft 34 against excessive magnetic influence.

Referring to the further modified assemblage illustrated diagrammatically in Fig. 5, this separator is quite similar to the one shown in Figs. 3 and 4, but the iron delivery end pulley 15 is also provided with a special magnet pole 33 with which a second auxiliary energizing coil 29 coacts and which is secured directly to the main magnet 8. The pulley supporting frames 16 and 17 of this embodiment of the invention are both formed of non-magnetic material so as to protect the bearings of both pulley shafts 32, 34 against undesirable magnetism or magnetic inuence, and both pulleys 14, 15 are formed of magnetic material in order to cause the coils 19, 29 and their respective poles 31, 33 to create zones of positive or north polarity adjacent to the lowermost peri heral portions of both pulleys. The effect on the entering burden is therefore to most effectively extract the magnetic pieces 25 from the advancing feed layer 22 and to cause these pieces to adhere to the lower belt run 18 until after they have been carried well beyond the sand conveyor 30 and over the iron delivery conveyor 28, thus insuring most efficient separation and removal of the separated ingredients.

Referring to the embodiment of the invention depicted in Fig. 6, wherein a transverse iron delivery conveyor 35 which is disposed laterally of and extends parallel to the sand conveyor 30, is provided, in this modification the coil 29 is energized to provide a negative or south zone of magnetic polarity at the lower portion of the pulley l5, while the other auxiliary coil 19 is energized to provide a zone of positive or north polarity adjacent to the opposite end pulley 14. The pulley supporting frames 16, 17 of this special separator may be formed of either magnetic or non-magnetic material and it is lpreferable to utilize the special poles 31, 33 when the frames are constructed of non-magnetic substance. When this modification is operating normally, the zone of positive polarity beneath the feed end pulley 14 will cause the iron to be effectively removed from the burden 22 at the pick-up zone, but the zone of negative polarity beneath the other pulley 15 will quickly repel the iron pieces 25 and permit them to drop into the iron delivery conveyor 35 after they have been carried across the sand discharge conveyor 30.

From the foregoing detailed description of the construction and operation of the various embodiments of the invention illustrated in the drawings, it will be apparent that either one or several of the auxiliary ma netic energizing coils 19, 29 may be utilized to modigy the separating action of the main magnet 8 at one or both sides of the latter. Either belt conveyors 21, 23, 24 or pan conveyors 27, 28, 30, 35 may be utilized to handle the feed burden 22, the sand 26 and the iron, and these conveyors may be disposed at various distances from the main conveyor belt run 18 and either in alinement therewith or transversely thereof, depending upon the characteristics of the particular burden 22 which is being treated. 'Iliis burden while normally being substantially dry, may contain more or less moisture and the ingredients may also be relatively loosely associated or compacted, but with the flexibility provided by the present invention any of these different conditions rrayl'l bie met and most eicient separation can be accompis e The improved auxiliary coils 19, 29 may be energized to produce either positive or negative fields of strong magnetic influence on either of the opposite sides of the rnain magnet, and the improved special poles 31, 33 may also be utilized to eliminate undesirable magnetic influence upon the bearings for the pulley mounting shafts 32, 34. The pulley supporting frames 16, 17 mayhowever be formed of either magnetic or non-magnetic material depending upon the characteristics of the burd :n 22, and while the invention is primarily advantageously applicable to in-line separators for foundry sand, the improved auxiliary energizing coils 19, 29 and special poles 31, 33 may also be likewise applied to cross-belt types of socalled self cleaning magnetic separators embodying reetangular magnets 8. I

lt should be understood that it is not desired to limit this invention to the exact details of construction and operation of the in-line magnetic separators specilically shown and described herein, for various modificatlons within the scope of the appended claims may occur to persons skilled in the art.

l claim:

l. In a magnetic separator, a main electromagnet having a medial pole surrounded by an energizing coil and opposite end poles spaced from the medial pole, all of said poles terminating in a common lower plane, a conveyor having a lower stretch movable past said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and non-magnetic substances along and beneath said conveyor stretch to cause said magnet to separate magnetic material from the layer while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and an auxiliary energizing coil cooperating with said conveyor stretch remote from said main magnet for altering the magnetic Vinfluence of said magnet upon the ingredients of the mixture.

2. In a magnetic separator, a main electromagnet having a medial pole embraced by an energizing coil and opposite end poles spaced from the medial pole, all of said poles depending toward and terminating in a common lower plane, an endless conveyor belt c oactng with pulleys at the opposite ends of said magnet and having a lower run movable past said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and non-magnetic substances along and beneath said belt run to cause said magnet to separate magnetic material from the layer while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and-an auxiliary. energizing coil cooperating with one of said pulleys for altering the magnetic influence of said main magnet upon the ingredients of the mixture.

3. In a magnetic separator, a main electromagnet havp ing a medial pole surrounded by an energizing coil and opposite end poles spaced from the medial pole, all of said poles terminating in a common lower plane, an-endless conveyor belt coacting with magnetic pulleys at the opposite sides of said magnet having a lower run movable past said poles substantially within said plane, means`for transporting a bulk layer of mixedv magnetic and nonmagnetic substances along and beneath said belt run to cause said magnet to separate magnetic material from the layer ,while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and an auxiliary energizing coil cooperating with one of said pulleys at a zone remote from the field of most eective action of said main magnet for altering the magnetic influence of said magnet at said zone.

4. In a magnetic separator, a main electromagnet having a. medial pole surrounded byan energizing coil and opposite end poles spaced from the medial pole, all of said poles terminating in a common lower plane, an endless conveyor belt coacting with magnetic pulleys at the opposite sides of said magnet having a lower run movable past said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and nonmagnetic substances along and beneath said belt run to cause said magnet tov separate magnetic material` from the layer while rmitting the non-magnetic ingredients to drop by gravity away from said magnet, and an auxiliary energizing coil cooperating with each of said pulleys to alter the magnetic inliuence of said main magnet adiacent to the pulleys. 1

5. In a magnetic separator, a main electromagnet having a medial pole and opposite end poles spaced from the medial pole, all of said poles depending toward and terminating in a common lower plane, a conveyor having a lower stretch movable past said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and non-magnetic burden beneath said conveyor stretch to cause said magnet to separate magnetic material from the layer while permitting the non-magnetic ingredicnts to drop by gravity away from said magnet, and an electric energizing coil cooperating with said conveyor stretch remote from said main magnet for altering the magnetic influence of said magnet upon the ingredients of the burden.

6. In a magnetic separator, a main magnet having a medial pole embraced by an energizing coil and opposite end poles spaced from the medial pole, all of said poles depending toward and terminating in a common lower plane. an endless conveyor belt coacting with pulleys at the opposite ends of said magnet and having a lower horizontal stretch movable past said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and non-magnetic burden longitudinally of and beneath said belt to cause said magnet to lift magnetic material from the layer onto said horizontal stretch while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and auxiliary energizing coils cooperating with said pulleys for altering the magnetic influence of said main magnet upon the ingredients of the burden.

7. In a magnetic separator, a main magnet having a medial pole surrounded by an energizing coil and opposite end poles spaced from the medial pole, all of said poles depending from a magnetic backing and terminating in a common lower horizontal plane, an endless con veyor belt coacting with magnetic pulleys at the opposite sides of said magnet having a lower run movable horizontally across said poles substantially within said plane, means for transporting a bulk layer of mixed magnetic and nonmagnetic burden longitudinally beneath said belt run to cause said magnet to pick up magnetic material from the layer while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and an auxiliary energizing coil cooperating with each of said pulleys at a zone remote from the field of most effective action of said main magnet for altering the magnetic influence of said magnet at said zone.

8. In a magnetic separator, a main magnet having a medial pole surrounded by an energizing coil and opposite end poles spaced from the medial pole, all of said poles terminating -in a common lower plane, an endless conveyor belt coactingvwith magnetic pulleys at the opposite sides of said main magnet and having a lower run movable past said poles substantially within said plane, means for transporting a bulk layer of mixedmagnetic and non-magnetic burden along and beneath said belt run to cause said magnet to separate magnetic material from the layer while permitting the non-magnetic ingredients to drop by gravity away from said magnet, and an auxiliaryelectro-magnet pole cooperating with each of said pulleys vto alter the polarity of the magnetic field liux beyond the opposite sides of said main magnet and adjacent to the pulleys. i

No references cited.

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