US2003430A - Apparatus for removing magnetic from nonmagnetic material - Google Patents

Description

June 4, 1935.,l

APPARATUS FOR REMOVING MAGNETIC FROM NONMAGNETIC MATERIAL R. E. CROCKETT Filed Aug. 24, 1932 2 Sheets-Shes?.- 1

Warn:

l INVENTOR.

ATTORNEY'.

BYV Y June 4, 1935.

E. CROCKETT APPARATUS FOR REMOVING MAGNETIC FROM NONMAGNETIC MATERIAL 2 Sheets-Sheet 2 Filed Aug.a 24, 1932 l" I' "u:

www: um* gen' o Il" INVENTOR.

ATTORNEYeS.

Patented June 4, 1935 UNITED STATES PATENT OFFICE APPARATUS FOR REMOVING MAGNETIC FROM NONMAGNETIC MATERIAL Application August 24,

12 Claims.

'I'he present invention relates in general to improvements apparatus for separating mixed solids having dierent characteristicaand relates more specifically to an improved apparatus for removing magnetic from non-magnetic material.

`Generally stated, an object of the invention is to provide a new and useful apparatus for segregating magnetic and non-magnetic material, automatically and in a highly effective manner.

While it has heretofore been proposed in the mining industry, to separate ore concentrates from tailings, it required two independent operations and machines in order to remove the tailings from the magnetic material, and to further segregate the concentrates from the middlings. This dual handling of the material is not only tedious and costly, but also requires more machinery and greater space for installation of the same.

It is therefore a more specific object of the present invention to provide an improved apparatus for separating magnetic ore concentrates and middlings from each other and from the tailings, both rapidly and effectively, and with but a single compact machine. Y

Another specific object of the invention is to provide a simple and highly practical apparatus for utilizing electro-magnetic force to segregate nely divided mixed particles having dierent characteristics.

A further specific object of the invention is to provide a new apparatus for separation whereby magnetic inuence is utilized to agitate mixed particles of magnetic and non-magnetic material, while a liquid such as Water may be employed in cooperation with the magnetic force to effect separation of the particles.

Still another specic object of the invention is to provide an improved concentrator especially useful in the mining industry, for separating a mixture of materials into different classes, such as tailings, middlings and concentrates.

Another specific object of the invention is to provide a simple, compact and highly emcient classier for segregating a continuous stream of bulk material into constituents having different characteristics.

A further specific object of the invention is to provide an automatically `functioning sepa- -rator which will effectively segregate an advancing layer of mixed granules into two or more accurately defined classes.

Still another specific object of the invention is to provide an improved magnetic Vseparating ma- 1932, serial No. 630,174 (ci. 209-232) chine which is exible in operation, and all parts of which, while being protected, are conveniently accessible for inspection, adjustment and repairs.

Another specic object is to provide a hydromagnetic separator operable with minimum liquid, wherein the magnetic particles of a mixture are separated under water, and the removed magnetic particles are subsequently withdrawn from the liquid by magnetic influence.

Another specific object of the invention is to provide -a compact magnetic .separator operable at minimum cost to effectively treat enormous quantities of material, and wherein the magnet structure is thoroughly protected against moisture even with parts thereof submerged.

A further specific object of the invention is to provide various improvements in the construction and mode of manipulating classifying devices, whereby the manufacture, assembly and operation thereof is facilitated, and the cost reduced to a minimum.

These and other objects and advantages will be apparent from the following detailed description. 'l

A clear conception of several embodiments of the invention may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views:`

Fig. 1 is a part sectional side elevation of one of the improved magnetic separators utilizing a liquid bath of water to aid in the separation;

Fig. 2 is a part sectional end view of the magnetic separator of Fig. l, the section having been taken through the center of the intermediate separating hopper;

Fig. 3 is a central longitudinal section through the separating and collecting hoppers of the machine of Figs. 1 and 2;

Fig. 4 is an enlarged part sectional side view of the magnet structure preferably employed in the improved separators;

Fig. 5 is a part sectional side elevation of another form of improved magnetic separator utilizing fluid jets to facilitate separation; and- Fig. 6 is an enlarged top View of the piping and jet delivery structure employed in the modified machine of Fig. 5.

Referring specifically to the embodiment of the invention shown in Figs. 1, 2 and 3 of the drawings; the improved separator comprises in general a waterproof multi-pole agitating magnet or series of magnets 8 having downwardly exposed pole pieces 9 the lower faces of which cooperate to form substantially a catenary curve; an endless non-magnetic band or belt I0 having its lower stretch movable along and in close proximity to the lower faces of the pole pieces 9; means for feeding mixed magnetic and non-magnetic material in bulk and in the form of a thin layer to the lower surface of the belt I0 within the magnetic field created by the magnets 8; and hydraulic means for washing the material being transported through the magnetic field by the belt IU.

The magnet structure is built substantially as shown in Fig.'4, and consists of a series of vertical magnetic cores II having the pole pieces 9 attached to lower extremities thereof, with nonmagnetic blocks I2 interposed between the adjacent pole pieces 9. Each core II is embraced by anenergizing coil I3, which may be energized from any suitable electrical source in such a manner that alternate, magnets produce field sections of the same polarity, while the intermediate magnets produce sections of opposite polarity. The magnets 8 may also be arranged in successive groups creating elds of different intensity. The initial group is preferably of high intensity and extends from the pick-up region of the feed chute entirely across the initial or tailings hopper and partially over the intermediate or middlings hopper. The intermediate group is of medium intensity and extends from the initial group along the catenary curve to a point just above the liquid level in the middlings hopper near the discharge end thereof, and the magnets of this group may be of decreasing intensity in the direction of travel of the lower run of the belt. 'I'he final group may be adjustable and of high intensity and extends from the end of the intermediate4 group to the end of the magnet structure, that is, beyond the de-watering chute and into the final discharge chute. 'Ihe magnet cores II and coils I3 are housed within a removable non-magnetic waterproof casing I4 which extends along the lower ends of the cores II above the pole pieces 9, and the end pole piece I5 may be made to project beyond the end magnet in the direction of travel of the belt I0. The magnet structure is preferably of considerably less width than the belt I0 and is supported from a main frame I6 formed of structural iron, by means of brackets I1 attached to a supporting side plate I8 to which the casing I4 and pole pieces 9 are secured.

The band or belt I0 the lower run or stretch of which is movable along the lower faces of the pole pieces 9 and spacer blocks I2, is supported upon a driving drum I9 and an idler drum 20, both rotatably supported in bearings mounted upon the main frame I8. 'Ihe driving shaft 2| which supports the drum I9, is mounted in fixed bearings and is adapted to be rotated at any desired speed, by means of power applied to a pulley 22. The supporting shaft 22 of the idler drum 20 is rotatably supported in movable bearings 23 which are adjustably supported upon inclined brackets 24 attached to the main frame I6, and the inclination of these brackets is such that the catenary curve of the lower stretch of the belt I0 is not materially changed by adjustment of the drum 20 throughout the limits provided. As previously indicated, the width of the be1t |0 is preferably somewhat greater than that of the magnet structure, and the length of the drums I9, 20 may be somewhat greater than the belt width.

' The means for feeding the material in the form of a thin layer to the lower surface of the belt I0, shown in Fig. 1, includes a set of superimposed inclined troughs 25, 26 the upper of which delivers ore to a medial portion of the lower trough 26, and the lower of which is supplied with liquid from a pipe 21. The admitted water mixes with the ore received from the trough 25, and the mixture is adapted to be discharged by gravity through a vertical pipe 28 into a scrubbing box 29. The side of the scrubbing box 29 has an elongated horizontal delivery opening which communicates with the upper end of an inclined feed chute 30 having a wooden or sponge rubber lining 3I therein the lower end of which is riiiled or otherwise roughened and extends in close proximity to and along the portion of the lower run of the belt I0 approaching the pole pieces 9. The roughened portion may be of any suitable shape having its surface adapted to distribute the particles of material in the form of a thin continuous layer of uniform thickness over the entire face of the belt I0 within the limits of the field produced by the magnets 8.

The hydraulic ine-ans for washing the material during its transportation through the magnetic field by the belt I0, specifically illustrated in Figs. 1, 2 and 3, comprises a series of three hoppers 32, 33, 34, 35 formed integral with each other and supported upon the main frame I6 beneath the magnets 8 by means of adjustable suspension bolts 36. The preliminary agitating hopper 32, may or may not be used, and this hopper 32 has its upper end in open communication with the feed chute 30 and has a iiuid injection pipe 32 communicating with its lower end. The initial separating hopper 33 is adapted to receive the non-magnetic particles or tailings which are removed by washing from the magnetic field, and this hopper 33 has an inclined or curved partition 31 in the upper end thereof forming a iiow intercepting baiiie directly below the magnetic field. The intermediate separating hopper 34 is adapted to receive the particles having'constituents of both magnetic and non-magnetic characteristics commonly designated as middlings, and this hopper 34 has two flow intercepting baiiies or partitions 38 therein directly below the magnetic separating field. The final separating hopper 35 is adapted to receive the particles of material having magnetic characteristics substantially throughout, ordinarily concentrates, and this hopper 35 has a transverse division wall 39 therein whichv extends downwardly from a point below the extended pole piece I5 to form an auxiliary excess water removing hopper 40 having a drain spout 4| at the lower end thereof. The baiiies 31, 38 may be made vertically adjustable, and these baffles aided by the division dams between the hoppers serve to enhance the washing action by retarding the liquid whichfis dragged along the magnetic eld by the belt I0 and the particles advanced thereby.

An abundant but regulated supply of water may be admitted upwardly into the middlings and tailings collecting hoppers 34, 33 through an upper water inlet pipe 42, and additional lower fluid inlets may be provided near the bottom of these hoppers to prevent clogging. A water spray 43 may also be utilized to wash the concentrate from the portions of the belt I0 leaving the magnetic separating eld, but this may in some cases be omitted. In order to maintain the concentrate in relatively dry condition, the amount of liquid admitted through the spray 43 when used, should preferably be limited. 'Ihe concentrate hopper 35 is provided with an open outlet pipe 44, but each of the other main hoppers 33, 34 is providedv with an intermittently opening mechanically actuated rubber covered discharge valve 45. These valves 45 are supported upon levers 46 through compression springs 41, and the levers 46 are pivotally supported from the lower portions of the adjacent hoppers 33, 34 and are swingable in vertical planes to alternately open and close the valves 45 by means of constantly rotating eccentrics 48 coacting with straps 49 cooperating through springs 48' with the swinging ends of the levers 46. While the valves 45 serve to discharge some of the excess liquid which is admitted to the hoppers 33, 34 through the pipes 42, and some of this water ls also carried over the discharge end of the middlings hopper 34 into the auxiliary hopper 46, provision is also made to carry off the remainder of excess liquid, over the sides of the hoppers 33, 34. The valves 45 and hoppers 33, 34, cooperate to dewater the finally discharged products to any desired extent due to the variability of the opening and closing periods of the valves and the extent of opening. Each side of each of the hoppers 33, 34, is provided with a vertically adjustable dam 50 cooperating with a recess 5| to provide a controllable overflow, and the dams 50 of the tailings hopper 33 are preferably set at a lower level than those of the hopper 34. The overflow liquid which passes through the auxiliary hopper 40 and over the dams 50 may be utilized for injection through the pipe 21 in order to save ore particles contained therein, or it may be otherwise treated for removal of the concentrates.

While the normal operation of the machine shown in Figs. 1, 2 and 3 during the exploitation Yof the improved process, shouldbe clearly apparent from the foregoing description, such operation will be briefly described. The mixed ore and tailings are delivered from the trough 25 into the trough 26 and arethoroughly mixed with liquid from the pipe 21, the mixture being delivered through the pipe 28 to the scrubbing box 29 where it is thoroughly agitated. 'Ihe uent mixture of water and solid materials is then discharged through the chute 3| over the hopper 32, and upon striking the roughened portion of the chute the solids are delivered in thoroughly agitated condition and in the form of a thin layer across the face of the advancing belt l0. Liquid is being admitted through one or more of the inlet pipes 42 and is rising in the hoppers 33, 34 thus thoroughly washing the entering film of material and causing the tailings to drop and to be discharged periodically together with excess liquid, through the valve 45 at the bottom of the hopper 33. When the advancing materiall reaches the hopper 34, the middlings are separated and periodically discharged together with some of the liquid, past the valve 45 at the bottom of the hopper 34, and these middlings may be reground for subsequent treatment for the removal of magnetic concentrates. The concentrates are carried along by the advancing belt I and when the auxiliary hopper 40 is reached, the excess liquid which is dragged along by the belt I0 is removed by the squeezing action produced by the final high intensity magnets which pull the concentrates against the conveying surface of the belt, whereupon the concentrates are deposited through the discharge pipe 44 after being removed from the influence of the final pole piece l5. The jet delivered from the spray pipe 43 then removes adhering material from the belt I 0. The excess liquid admitted to the hoppers 33, 34 which is not removed past the valves 45 and through the auxiliary hopper 40, overflows at the dams 50. As previously indicated, the magnet groups are, initially of high intensity at the pick-up region and across the tailings hopper 33 and slightly into the middlings hopper 34, secondly of medium intensity over the greater portion of the middlin'gs hopper 34, and finally of adjustable high intensity to the end of the magnetic fleld, so as to successively separate the several grades and to dewater the final concentrates. The successive pole pieces 9 are of reverse polarity so as to constantly maintain the magnetic particles in a state of agitation during their transportation. The tension of the belt I0 may obviously be readily adjusted by shifting the bearings 23, and such adjustment does not materially affect the curvature of the lower run of the belt. l

In the modied embodiment of the invention specifically illustrated in Figs. 5 and 6, the magnet structure, belt arrangement and frame construction are substantially the same as those previously described, but the modes of feeding the raw material and of separating the constituents, are slightly different. The material feeding means of the modified machine, may comprise a preliminary funnel 59 communicating upwardly with the medial portion of a feed chute 60 having a woodenv or rubber lining 6| therein, and the lower portion of the lining 6I which is in close proximity to the belt I0, may be provided with a material distributing roughened portion 62. The fluent mixture of solids and liquid admitted to the upper end of the chute 60, may be caused to flow .into the funnel 59 where it can be agitated and intimately mixed by air or liquid delivered into the lower funnel end through a valve controlled pipe 62', or it may be mixed and agitated in a scrubbing box 29 and without utilizing the funnel 59.

'Ihe means for effecting removal of the several classes of material from the magnetic field of the modification, is again preferably hydraulically actuated, although air or gas may be used to advantage in the treatment of certain materials. A series of hoppers 63, 64, 65 formed integral with the funnel 59 and adjustably supported upon the main frame I6, is disposed beneath the magnetic field produced by the magnets 8 and traversed by the belt I6. The successive groups of magnets 3 of this machine are preferably of gradually diminishing strength throughout the separating zone. 'Ihe initial hopper 63 is adapted to receive the non-magnetic particles or tailings, while the intermediate hopper 64 is adapted to receive the middlings, and the final hopper 65 receives the concentrates. Each of the hoppers 63, 64 is provided with an open outlet pipe 66, and the final hopper 65 likewise has a constantly open outlet pipe 68 communicating with the lower end thereof. The nal hopper 65 may also be provided with a transverse division Wall 69 forming a de-watering hopper 10 having a liquid discharge spout 'll at the lower end thereof, but this partition wall 69 may in some cases be omitted. Removal of the graded particles may be effected by means of a series of spray pipes 13, I4 shown in detail in Fig. 6. The pipes 13 are disposed above the middlings hopper 64 and have either elongated slots or series of orifices directed perpendicular toward the material transporting surface of the belt l0, while the pipe 14 is disposed above the tailings hopper 63 and may have its delivery slot or orifices disposed perpendicular or at an oblique angle relative to the belt surface. All of the pipes 13, 'I4 may communicate with a common fluid supply header 15 having a regulating valve '16, through which fluid, preferably liquid under pressure may be delivered to the spray producing pipes. This modified machine may also be provided with a final wash spray for the belt l0, if it is desired, although this may be omitted.

While the normal operation of the modified separator of Figs. 5 and 6 should also be apparent from the foregoing description, the said operation will be briefly described. The material to be treated is fed to the modified machine in a manner similar to that previously described in connection with the machine of Fig. 1, and the initial mixture of the material thus admitted may be enhanced by the funnel 59 and the injection of fluid into this funnel through the pipe 62'. As the thin layer of material is advanced along the magnetic field by the lower run of the belt I0, the jets of fluid delivered from the spray pipes 13, 14 remove the classified particles from the agitated mixture being transported by the belt, and deposit these particles into their respective hoppers 63, 64. The concentrates are carried over the final hopper 65 and drop by gravity as they are cremoved from the influence of the magnetic eld. The wash spray 43 may again be utilized to remove any adhering particles from the belt l0, and the separated materials are delivered from the hoppers 63, 64, 65 through the pipes 66, 68. As heretofore described, the magnets 8 are of decreasing intensity in the direction of travel of the lower run of the belt l0 and successive magnets are of reversed polarity, thus enhancing the washing action afforded by the sprays.

From the foregoing description, it will be apparent that the present invention provides a simple and highly efficient apparatus for removing magnetic from non-magnetic material, and of automatically segregating the removed particles into accurately defined classes or grades. Obviously, the number of grades or classes produced may be enlarged beyond three, by merely adding more intermediate hoppers and by properly controlling the energization of the magnets 8. The intensity of the magnetic eld should de crease or increase in the direction of travel of v the belt I 0, so as to enhance the effectiveness With which the particular materials handled, may be separated and removed from the belt surface. It will also be apparent that the degree of coarseness or fineness of the material may be readily varied as desired, by merely varying the intensity of the magnetic field, and by utilizing either a hydraulic bath or jets to effect removal of the non-magnetic particles from the separating zone.

The hoppers of both machines may be adjusted relative to the main frame I6, and the magnets 8 may be readily removed as a unit to permit removal of the belt I0. The casing I4 within which the cores Il and coils I3 are housed, effectively protects these parts against moisture while permitting location of the magnetic field within a zone of abundant moisture. The alternate polarity of the magnets 8, While effectively retaining the magnetic particles within the magnetic field, serves to intermittently reverse and thereby agitate the advancing particles' and thus insures production of accurate nal grades or classes.

When the separation is effected beneath the surface of the liquid, there is a distinct advantage since difliculties introduced by surface tension of the liquid when it is attempted to separate at the liquid surface, are entirely eliminated. The baffle plates 3l, 38 in the hoppers 33, 34 serve to retard the velocity of the entering liquid and to distribute the same gently over the material transporting surface of the belt I0, and the adjustable dams 50 cooperate with the valves '4,5 to maintain the desired levels of liquid within the hoppers 33, 34. By setting the dams 50 of the tailings hopper 33 lower than those of the hopper 34, the bulk of the floating material will be drawn ofi before the liquid near the magnetic field is caused to flow into the intermediate hopper 34 by the advancing belt l0, so that theliquid in the latter hopper will remain relatively clean. Furthermore, the clean washing water will be introduced into the middlings hopper and because of the lower Water level in the tailings hopper will flow into it, reversing the stream of dirty water which the travelling belt would tend to drag over into the middlings hopper. This will also increase the washing action on the material on the belt. It will also be noted that the preponderance of clean make-up water is admitted near the point where the material on the belt has become a concentrate, thus giving the latter a flnal washing in clean water. The advancing belt l0 also tends to carry liquid in relatively large quantities over the discharge wall of the intermediate hopper 34, and this liquid quickly drains through the auxiliary hopper 40 and is discharged through the spout 4|. The spray 43 may be disposed as shown in Fig. 1 or it may be advanced along the face of the drum lI9 as in Fig. 5, in order to reduce the amount Aof water required for nal removal of adhering particles from the belt I 0, to a minimum. The opening and closing movement of the discharge valves.45 may be adjusted in any convenient manner in order to comtrol the liquid level in the hoppers 33, 34, and the rubber facing on these valves will prolong their life.

When the separation is effected by the spray process, the hoppers 63, 64, 65 need not have any liquid confined therein, but a combination of the two processes may sometimes be desirable. In either case, the material admitted to the belt I0 and to the magnetic field, should be thoroughly mixed and agitated, and this result is attained with the aid of the funnels 32, 59. A preliminary mixer and feeder such as shown in Fig. 1, may also be utilized in conjunction with the modified machine, and any number of spray pipes 73 may be utilized. As previously indicated, the final wash spray pipe 43 when utilized, will remove all particles from the advancing belt'l surface and will leave the belt in clean condition ready for subsequent separating operations. It will be apparent that the features of either of the specific types of machines herein shown and described, may obviously be applied to or substituted for those of the other. For example, the funnel type of feeder will be found desirable for feeding extremely finely divided material with minimum undesirable disturbance and should be utilized when treating fine ore with the submerged type of machine.

It should be understood that it is not desired to limit the invention to the precise construction of the apparatus herein ,shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patentz- 1. In a separator, means forming a liquid basin, means for producing a magnetic field of substantially catenary shape having successive sections of reversed polarity and disposed beneath the liquid level in said basin, a belt having a lower stretch transportable along said field while immersed in said liquid, means for feeding mixed magnetic and non-magnetic material to said belt stretch, a series of baffles disposed in said basin in close proximity to said belt stretch, and means for discharging separated material from said basin tog-ether with some of the liquid.

2. In a separator, means for producing a magnetic field, a belt movable through said field along substantially a catenary curve, the portion of said belt at the medial portion of said curve being immersed in liquid, means for feeding mixed granular material to said belt at one side of said immersed portion, means for removing graded materials from said belt at said immersed portion, and means for de-watering and discharging the dry residue at the other side of said immersed portion.

3. In a separator, means forming a liquid basin, means for producing a downwardly curved magnetic field having successive sections of alternate polarity and having its lowest portion disposed beneath the level of the liquid in said basin and the opposite ends thereof above sai-d liquid, a belt having a substantially catenary portion transportable along said eld and through said liquid, means for feeding mixed magnetic and .non-magnetic material to said belt above the liquid in said basin, a series of deiiector bailles disposed in said basin in close proximity to the immersed portion of said belt, and means for discharging separated material from said basin.

4. In a separator, a series of magnets associated with each other to produce an elongated magnetic ileld successive sections of which have opposite polarity, a conveyor cooperable directly with the poles of said magnets and movable through said field to advance a thin layer of mixed magnetic and non-magnetic particles along said field, means forming a basin containing liquid within which the medial portion of said leld is immersed, the end portions of said field being disposed above said liquid, means for delivering the mixed material to said eld in the direction of travel of said conveyor and at one ,of said end portions, means including said basin for subsequently rev moving from said layer the particles having both magnetic and non-magnetic constituents, and means at the opposite end of said eld for removing the particles having only magnetic qualities.

5. In a separator, means forming a liquid basin,

means for producing a magnetic field having end portions of higher intensity than the intermediate portion and having said intermediate portion immersed within the liquid of said basin, means for conveying granular material along said ileld, means for feeding such material to said conveying means at one of said field portions of high intensity, and means for removing magnetic material alone from said conveying means at the other of said field portions of high intensity, the

latter of said eld portions of high intensity acting to press the material against said conveying means to de-water the magnetic material prior to naal. removal thereof.

6. In a separator, means for producing a magnetic eld having relatively high intensity at an end thereof, a belt having a substantially catenary flexible portion movable along said field to transport material toward said high intensity end of said field, and means forming a basin containing liquid through which said belt portion advances before reaching said high intensity end of said field, said high intensity acting to de-water the material `after leaving said basin.

7. In a separator, means forming'a liquid basin, a belt movable through the liquid in said basin to advance material therealong, means for subjecting the material conveying surface of said belt to magnetic influence while the same is immersed within said liquid, and curved material divert-v ing baffles disposed entirely within said liquid and extending in close proximity to the material transporting surface of said belt.

8. In a separator, means forming a liquid basin, a belt movable through the liquid in said basin to transport granular material, means for subjecting the material transportingy surface of said belt to magnetic inuence, and a series of curved baiiles immersed in said liquid and extending transversely of and in close proximity to said belt surface, said baffles being curved upwardly in a direction opposite to the direction of travel of the adjacent portion of the belt.

9. In a separator, means for producing a magnetic field, a belt having a section movable longiV tudinally through said eld, means forming tailings and middlings receiving liquid basins through which said belt section advances in succession, and adjustable means for maintaining the liquid level in said tailings basin below that in said middlings basin so as to produce a flow of liquid along said belt in a direction opposite to the direction of belt movement.

l0. In a separator, means for producing a magnetic field, a belt movable longitudinally through said field, means forming adjoining compartments having liquid, therein through which said belt advances, -said compartments being separated by a partition, and adjustable means for causing a flow of said liquid over said partition and along said belt in a direction opposite to the direction of travel of the belt.

11. In a separator, a flexible conveyor having a portion thereof movable while submerged in liquid along a ,substantially catenary curve, a series of magnets of alternate polarity having pole faces of substantially catenary formation disposed closely adjacent to said conveyor portion, means for delivering mixed magnetic and non-magnetic material to said conveyor while approaching said magnets, and means for removing the non-magneticjand magnetic constituents from said conveyor portion in succession.

12. In a separator, a flexible conveyor having a portion thereof movable while submerged in liquid along a substantially catenary curve, a series of magnets of alternate polarity Ahaving pole faces of substantially catenary formation disposed closely adjacent to said conveyor portion, means for delivering mixed magnetic and non-magnetic material to said conveyor while approaching said magnets, means for removing the non-magnetic and magnetic constituents from said conveyor portion in succession, and means for subjecting the magnetic constituents to in creased magnetic influence prior to removal thereof from said conveyor.

ROBERT E. CROCKE'IT.

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