US2675918A - Magnetic separator - Google Patents

Description

W. H. NEWTON MAGNETIC SEPARATOR April 20, 1954 3 Sheets-Sheet 1 Filed May 7, 1951 //v\/E/v7-0R; WILLIAM H. NEWTON,

April 20, 1954 w. H. NEWTON' 2,675,918

MAGNETIC SEPARATOR' Filed May 7, 1951 3 Sheets-Sheet 2 /N\/ENTO,Q; WILLIAM H. NEWTON,

ATTY- April 20, 1954 w. H. NEWTON MAGNETIC SEPARATOR 3 Shets-Sheet 5 Filed May 7 1951 //v VE/V TO/Q, WILLIAM H.NEWTON,

ATT'Y.

Patented Apr. 20, 1954 i J MAGNETIC SEPARATOR William H. Newton, Blacklick, Ohio, assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Application May 7, 1951', Serial No. 224,89?

This invention relates to a magnetic separa tor, and an object of the invention is to provide such a device which will do a very thorough job of removing and recovering all or substantially all of the magnetic constituent in a pulp mixture without necessarily attempting particularly to clean the concentrate or magnetic material which may be allowed to contain a relatively high percentage of non-magnetic material, as compared with some previous known types of magnetic separators.

A further object of the invention is to provide a-magnetic separator in which the essential nonmagnetic pulp is subjected to a rather extended travel under the influence of magnets, with a carrier moving in the opposite direction from the movement of the pulp so as to efiect a very eificient and complete recovery of all the magnetic material.

Still another object of the invention is to provide apparatus, as above described, in which coarse tailings or non-magnetic material is removed before the completion of the travel of the tailings or non-magnetic material from the feed chamber to discharge.

Still another object of the invention is to provide apparatus of the above mentioned type in which an upward current classifier is employed intermediate the feed chamber and the final tailings discharge which will receive coarse tailings and separate any fine tailings therefrom which are subjected to further magnetic treatment.

' Another object of the invention is to provide a modified form of apparatus in which there is a more efiicient cleaning of the concentrates than with other embodiments of said invention.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

Fig. 1 is a side elevational sectional view showing one form of magnetic separator incorporating features of my invention; I I Fig. am a plan view, with parts broken away, showing the separator of Fig. 1; I

Fig. 3 is a view, generally similar to Fig. 1, of a modified form of apparatus incorporating my invention;

Fig. 4- shows in section a further modification of the device of Fig. 3;

Fig. 5 shows a still further modification of the device of Fig. 3; and Fig. 6 shows in section still a further modification of the device of Figs. 1 and 2,,

11 Claims. (01. 209-232) All the figures of the drawings shows devices which are quite similar and it is to be distinctly understood that unless a contrary fact is clearly illustrated in the drawings or described in the specification, any essential structure of one modification is or may be employed with the other.

With particular reference first to the machine of Figs. 1 and 2 of the drawings, there is illustrated a frame ll] carrying a box generally designated H which has vertically spaced generally upright side walls and a generally cylindrically formed bottom which is made up of a number of segments as hereinafter described more completely. Mounted'to rotate in the box II is a non-magnetic carrier in the form of a drum I2 which may be rotated by drive gearing, including a motor l3 (see Fig. 2), in the direction of the arrow seen in Figs. 1, 3 and 4 of the drawings. Within the drum [2 there is a non-rotary or stationary, but adjustable, magnet assembly I l, preferably adjustable about the transverse horizontal axis of rotation of the drum [2. I

The above described structure is of essentially standard design and may follow, for example, the disclosure of the U. S. patent to P. L. Stefiensen, No. 2,160,628, dated May 30', 1939. I I

The carrier disclosed is in the form of the drum 12 though it is to be understood that within certain broad aspects of my invention a belt or other well known type of carrier may be employed.

The novel features of this invention result from the construction of the separator box H and particularly the relation of the various feed chambers, discharge chutes, pulp passageways and the like therewith. It will be noted by reference to- Fig. l of the drawings that the magnet assembly l4 extends over an arc of approximately ninety degrees, it being slightly in excess thereof. The adjacent magnetic poles are of op: posite polarity so that the magnetic material which adheres to the carrier or drum l2 will move or shift as it comes successively under the influence of adjacent poles. The magnet assembly I 4 is associated with the lower part of the drum and by "lower part is meant the pOrtion below a horizontal plane passing through the axis of rotation thereof. It will be seen that the drum l2 extends into the box ll so that slightly less than one hundred and eighty degrees of said "lower part of said drum is within said box II. I I Considering the various significant portions which are associated wither form a part of the substantially semi-cylindrical bottom of said box H, the first structure encountered, starting from the left side and moving to the right, as viewed in Fig. 1, is a concentrates or magnetic material discharge chute l5, the upper edge of which is closely adjacent to the lower surface of the periphery'cf the drum [2. In this connection it may be stated that the lower surface means the radially outward surface of said drum or carrier I2, or, in other words, the surface which is on the opposite side of the carrier [2, as compared with the side adjacent the faces of the individual magnetic poles of the magnet assembly l4. This, of course, means the surface upon which the magnetic material is carried by the non-magnetic carrier l2 under the influence of the magnets of the as-' sembly M. The concentrates discharge chute i5 is located so that material on the carrier I2 adjacent it has just passed out of the influence of the last magnet of the assembly l4 and thus is free todischarge thereon as it will. If desired, a spray [6 may be provided to aid this discharge of the concentrates or magnetic material out of the chute I5. In some cases the spray i6 is not required.

Closely adjacent to the discharge chute l5, and preferably in all of the illustrated embodiments of my invention directly below it, there is a feed chamber I! by which the mixed magnetic and non-magnetic materials, which may be called the concentrates and tailings, preferably in the form of a liquid pulp, are fed to the adjacent surface of the rotating drum l2. Said chamber I! may be fed from a feed pipe 18 in which the materials to be separated, mixed with adequate water to form a pulp, are carried. The normal level of this pulp is clearly illustrated in Figs. 1, 3 and 6 of the drawings.

If desired, a concentrates wash spray pipe 49 may be provided for washing the concentrates or magnetic material which is carried by the drum [2 as it rotates in a clockwise direction and is thereby moved towards its discharge position onto the chute I5. In some instances the wash spray pipe I9 is omitted.

It is to be noted that the feed chamber I1 is generally opposite the last pole of the magnet assembly I4. As a consequence it is obvious that any magnetic material in the pulp, which is magnetically attached to the adjacent surface of the drum or carrier l2 adjacent the feed chamber II,

will only travel a relativel short distance before it passes out of the influence of said last pole of the magnet assembly and is discharged over chute l5, and in the illustrated embodiments of my invention (except Fig. 6) only a single one of the poles of the magnet assembly M will have any significant influence in attracting this magnetic material. The consequence of this is that the concentrates or magnetic constituent of the pulp does not receive any appreciable washing or cleaning action to remove entrapped non-magnetic or tailings therefrom. The result is that in this particular separator significant portions of tailings or non-magnetic material may be discharged with the concentrates or magnetic material. This is totally without objection in connection with certain jobs for which this magnetic separator (except Fig. 6) is particularly designed, for the following reasons.

One of the principal, though not exclusive, uses of magnetic separators incorporating my invention, is in recovering the medium which is used in a non-magnetic or heavy medium process or method for the separation of fine non-magnetic minerals from gangue. For example, one well known way of treating non-magnetic ore or coal to separate the values from the gangue is by heavy medium process. One recognized way to derive the heavy medium is by finely divided magnetite or ferrosilicon, or a mixture of the two. The medium is sometimes used, for example, in a cyclone type separating vessel. For example, in a cyclone process the products are a float and a sink. The float will be gangue with some'separating medium. The sink will be the non-magnetic mineral with some medium. The next problem then is to recover the medium both from the float and from the sink. Each then will be individually treated by a magnetic separator of the type involving my invention. In the case of the float the concentrates or magnetic material will be the medium, and the tailings will be gangue. In the case of the sink, the concentrates or magnetic product will again be the medium, and the tailings will be the non-magnetic mineral or values. In other words, the magnetic separators of my invention are very useful in recovering the magnetic medium from either the non-magnetic gangue or the non-magnetic values or mineral which are individual products of a cyclone separator. It is to be understood; however, that this is only one illustration of important uses of my invention, and others may occur to those skilled in the art. In fact, it is obvious that in a broad sense, in any case where a complete removal of all magnetic materials from the pulp is desired, in which the solid particles are of relatively small sizes, this invention may be very useful.

The tailings pulp flowing from the feed chamber I? is formed in a relatively thin or shallow stream provided by av passageway which is preferably relatively long and has a relatively low height. The word height, as here employed, is intended to mean the dimension substantially at right angles to the adjacent surface of the drum or carrier I2. This elongated thin or lowheight passageway is provided by the lower sur face of the drum or carrier [2 and adjacent curved surface provided by the curved bottom portion 20 of the box II which is of non-magnetic material. This bottom portion or plate 20 H in the embodiment illustrated in Figs. 1 and 2 extends over an arc of approximately sixty degrees, and the elongated low-height or thin passageway extends along the surface of the drum l2 past three adjacent poles of the magnet assembly M which are of successively different polarity.

The upper surface of the bottom plate 20 is preferably covered by a rubber covering 21 or the like to prevent undue wear of the plate 26 under the abrasive action of the tailings pulp.

Adjacent the bottom edge of the plate 20 and generally in a vertical upright plane which passes through the axis of the drum l2 there is a spigot discharge chamber 22 which is adapted to receive the coarse tailings. This prevents building up and possibly clogging of the elongated passageway by large particles which might settle at the lowest area of said passageway. The chamber 22 is controlled by a restricting discharge opening large enough to pass the large gangue but not open enough to discharge all of the pulp. It is, of course, to be understood that the pulp being treated is all relatively small size material, such as of the order of one-fourth inch by zero. As a consequence, the so-calledlarge tailings particles will generally have a maximum size of onequarter inch.

It is to be noted that the spigot discharge chamber 22 is located adjacent the carrier 12 some place between the extremities of the magnet assembly [4 as a consequence of which the tailings pulp will continue to flow through the restricted passageway, above described, beyond said discharge chamber 22. As clearly illustrated in Fig. 1 of the drawings, this restricted passageway is continued in the direction of flow of the tailings pulp beyond the chamber 22 by a bottom plate 23 which, for practical purposes, may be considered as a continuation of the bottom plate 20 and of similar material, since the passageway which it provides is essentially the same size as the previously mentioned narrow passageway, except that, if desired, no liner, equivalent to the liner 2i, need be applied. This is because most of the wear due to the abrasive action above mentioned will take place in the passageway between the chamber l1 and the spigot discharge chamber 22 because of the mentioned large or coarse gangue particles.

The bottom plate 23 extends to a tailings overflow or pulp discharge chamber 24 which is located adjacent one of the end poles of the magnet assembly I l. The weir formed by the lower edge of the chamber 25 is obviously located below the upper edge of the discharge chute I 5, as a consequence of which the fluid pulp will obviously flow from the chamber I? to the discharge chamber 24. This flow of material is essentially downward since the feed chamber I! is above the discharge chamber 24, though this fact is more an incident of the proximity of the feed chamber H to the concentrates discharge chute I5 than a matter of fundamental importance.

In the operation of the device of Figs. 1 and 2, relatively fine material, such as one-fourth inch by zero, including particles of both magnetic and non-magnetic material, of which the nonmagnetic material may be either non-magnetic iron ore, coal, refuse or tailings, or the like, with an adequate amount of water to provide a thin pulp, is delivered by the feed pipe I8 to the feed chamber I! from which the pulp will flow in a thin stream substantially over the full width of the surface of the drum I2 through the elongated thin or low substantially uniform height passageway formed between the outer surface of the drum I2 and the bottom plates 2| and 23 of the box H and into the tailings discharge or overflow chamber 24.

As this pulp first contacts the periphery of the carrier or drum I2, the magnets above said carrier will attract the magnetic particles which will form in a relatively thin layer on the outer surface of said drum i2 which is rotated counterclockwise as illustrated by the arrow, thus carrying the magnetic material forward or upward and out of the path of the magnetic flux. The magnetic material or concentrates will then discharge by gravity either with or without the aid of water from the spray pipe I6 onto the chute I5 from which it will be discharged into any desired receptacle. If desired, the concentrates may be washed by water from the spray pipe 19 as said concentrates start their upward movement along the surface of the drum I2.

The action of the magnetic field and the carrier I2 on those magnetic particles which are moving along in the pulp stream toward the discharge chamber 24 is of particular significance. It is, of course, evident that most of the magnetic material is immediately removed from the flowing stream or the feed as it leaves the feed chamber I! or shortly thereafter, in the flow of said stream toward the tailings discharge chamber 24. As a consequence, the flowing stream is very lean in-magnetic material content and the quan 6 tity of magnetic material picked up by the drum I2 under the influence of the magnetsis small at all areas except substantially adjacent the magnetic pole near the feed chamber I'l. Furthermore, as the stream flows from the feed chamber I'I through the restricted passageway,

above described to the discharge chamber 24 the quantity of magnetic material progressively decreases toward the discharge chamber 24 since magnetic particles continue to be picked up from this stream'and carried on the surface of the drum l2 which moves counter to the direction of flow of said pulp stream.

It is a known fact that magnetic flux will take the path of lowest reluctance and as a consequence where there is a concentration of magnetic materials on the surface I2, namely, ad-- jacent the feed chamber I1 and discharge chute I5, most of the flux will flow through this concentrated mass of magnetic material and there will be little magnetic attraction in those areas closely adjacent this concentrated area.

Stated another way, since most of the magnetic material is removed adjacent the last pole of the magnet assembly I 4, it is evident that there will not be any heavy areas of concentrated material beneath any subsequent poles of said assembly I4, as a consequence of which the full strength of the magnetic poles, save only the first or left-hand one, as viewed in Fig. 1, will be available to catch those magnetic particles carried by the thin stream in the passageway provided by the surface of the drum I2 and the bottom plates 2! and 23.

Furthermore, it is obvious that as the pulp flows toward the discharge chamber 24 it becomes leaner and leaner in magnetic material content and under normal circumstances the probability of these magnetic particles coming close to the drum surface becomes less and less. In those machines of the drum or belt type where the tailings flow in the same direction as the drum or belt, there is a maximum of magnetic material on the drum or belt surface at the point of tailings discharge where, as above stated, the magnets have the least effect so far as picking up material not adhering to the belt or drum.

In the arrangement of my invention the condition is just the reverse and the short circuiting effect of magnetic material on the surface of the drum I2 progressively decreases as the pulp stream moves toward its discharge position. By the time the pulp stream has reached this di charge position the carrying surface of the drum or carrier I2 will be substantially, if not entirely, devoid of any adhering magnetic material, thus insuring a maximum of attractive force or flux available to catch those particles of magnetic material which have not previously been attracted to said drum surface. As a consequence of this arrangement, there is almost always a substantially complete recovery of the magnetic material, and the discharged tailings of nonmagnetic material will be substantially entirely free of said magnetic material.

In Fig. 3 a magnetic separator which, except for certain differences, follows substantially the construction of the machine illustrated in Figs. 1 and 2. The only significant difference is the complete elimination of the spigot discharge chamber 22 for removing coarse tailings. The device of Fig. 3 is preferably employed when the material being treated is of smaller size than previously men--, tioned; for example, where there is complete of the drawings there is illustrated absence of material of the order of one-fourth inch and where the largest particles may, for example, be of the order of one-sixteenth of an inch. Except for the possibility of withdrawing the large particles of tailings at a position along the narrow passageway between the feed chamber H and the discharge chamber 24, the operation or" the machine of Fig. 3 is essentially the same as the machine of Figs. 1 and 2.

In Fig. 4 of the drawings another slight modification of the machine of either of Figs. 1 and 2 or that of Fig. 3 is illustrated, in which a pulp feed pipe 25 is substituted for the feed pipe It to feed chamber ll. Otherwise the machine is fundamentally the same. This form is preferably used where there is considerable larger material which might not be lifted upwardly by the upwardly flowing water in the feed chamber I! of Figs. 1 and 3, the feed from pipe 25 being essentially tangent to the periphery of drum ii.

In Fig. 5 of the drawings still a further modiiication, particularly of the bottom plate of the box I I, is suggested, the structure otherwise following that of the machine of Figs. 1 and 2, or 3. In this arrangement an upward current classifier 26 is provided, it being interposed in the bottom plate of the box ll between a plate 2'] and a plate 23 thereof. It is to be noted that the plate 2! isshorter than the plate 29 in the device of Fig. l, the plate 28 being approximately the same length as the plate 23. The upward current classifier 28 reduces the effective length of the restricted passageway between the feed chamber ll and. the discharge chamber 25, as compared with the device of Fig. 1 or the device of Fig. 3. Otherwise, however, this passageway is essen tially the same as those of said devices of Figs. 1 and 3.

The upward current classifier Z8 is provided with a spigot control material discharge pipe 29 controlled by a spigot, not shown, and is provided with a water feed pipe 3% by which water is fed to the chamber of the classifier 26 and flows upwardly therethrough, flowing with the pulp flow through that portion of the restricted passageway adjacent the plate 23 to the overflow or discharge chamber 24. The upward current classifier 26 will, of course, provide for the removal of the larger particles of tailings, while carrying the smaller particles into that portion of the restricted passageway between said upward current classifier and said discharge chamber 24. Except for this added feature, the operation is essentially the same as above described in connection with the devices of Figs. 1 and 3.

In Fig. 6 of the drawings there is illustrated a further modification which may be applied to the structure of Figs. 1 and 2 or of Fig. 3 and which produces a slightly different result from that above described in one important particular. Otherwise the operation is generally the same. It will be noted that the feed chamber H of the devices of Figs. 1 and 3 has been replaced by a somewhat different feed chamber 3|. Of importance is the fact that the feed chamber 3| provides for feeding the pulp to the elongated passageway above described at a position substantially adjacent the next to last magnetic pole of the magnet assembly i4. As a consequence the concentrates will be subjected to the successive influence of the last two adjacent magnets, and the shifting of said magnetic material as it is carried from the influence of one of said poles to the other will take place. Furthermore, in this instance the spray pipe i9 is of considerable importance because it will be relied upon to wash the concentrates and thereby remove to an appreciable extent any entrained or inhering non-magnetic material or gangue. In other words, the concentrates in this form of invention will be much cleaner and freer of gangue than in any of the other embodiments.

It is to be further particularly noted that this spraying action takes place within the feed chamber itself and yet the spraying fluid or water is not submerged within the normal feed pulp. Thus it is entirely clean water and can efiiciently wash the concentrates without any interference from the feed pulp.

It is furthermore to be noted that this concentrates washing water Will flow largely back into the feed chamber Si, as a consequence of which any magnetic material, which may be washed oif by it, will not be lost but will become a part i the pulp stream which flows through the previously mentioned long narrow passageway to the discharge chamber. It is, of course, evident that the chamber 3! will provide a somewhat lower discharge weir or lip, as compared with the devices of Fig. l or 3, as a consequence of which the normal feed level will be lower than that illustrated, for example, in Fig. l of the drawings. Nevertheless it will still be higher than the discharge weir or lip of the overflow or discharge chamber 24. Should it become necessary, said discharge weir or lip of the overflow or discharge chamber 25. Should it become necessary, said discharge weir or lip of the overflow or discharge chamber 24 may be lowered in any desired manner to insure the desired flow of the pulp from the feed chamber iii to the discharge chamber 24.

Insofar, therefore, as the arrangement of Fig. 6 provides for a more thorough cleaning of the concentrates, this particular embodiment of my invention incorporates a feature which is not present in the same degree in the apparatus of the other figures. It may be pointed out, however, that in any case where the wash pipe I9 is provided, for example, as illustrated in Figs. 1 and 3 of the drawings, there will be to some extent an improved cleaning of the concentrates,

' as compared with the arrangement in which said wash pipe and wash water are omitted, which, as above stated, they may be in some forms of the invention, particularly where a cleaning of the concentrates is not of importance.

It is to be noted that regardless of which of the various embodiments of the invention is employed, the important common feature of making available a high flux concentration with a progressively decreasing amount of flux shortcircuited as the pulp stream flows toward the discharge is present.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and applicant therefore wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. A magnetic separator including a drum type carrier, a box adapted to receive said carrier and hold water, magnets positioned above a run of said carrier as it travels through said box,

said carrier being operable to'move below said magnets from one side of said box to the other, a gangue discharge below said carrier and adjacent one side of said box, a concentrates discharge below said carrier and adjacent the other side of said box, said carrier when in operation moving from said gangue discharge toward said concentrates discharge, said magnets extending above said carrier between said gangue discharge and said concentrates discharge and terminating adjacent each, said concentrates discharge being above said gangue discharge, an upward cur-' rent classifier type of coarse gangue chamber below said carrier intermediate said gangue discharge and said concentrates discharge, and a feed chamber adjacent and below said concentrates discharge and above said gangue discharge whereby pulp fed to said box will flow counter to the movement of said carrier and below it while flowing to said gangue discharge, said box including means providing an elongated passageway of restricted dimension perpendicular to said carrier which passageway receives feed from said feed passageway and conducts saidfeed adjacent said carrier as the feed travels toward the gangue discharge at the other side of the box, said coarse gangue chamber being intermediate the ends of said passageway.

2. A magnetic separator including a carrier, a box adapted to receive said carrier and hold water, magnets positioned above a run of said carrier as it travels through said box, said carrier being operable to move below said magnets from one side of said box to the other, a gangue discharge below said carrier and adjacent one side of said box, a concentrates discharge below said carrier and adjacent the other side of said box,,said carrier when in operation moving from said gangue discharge toward said concentrates discharge, said concentrates discharge being above saidgangue discharge, an upward current classifier type of coarse gangue chamber below said carrier intermediate said gangue discharge and said concentrates discharge, and a feed chamber adjacent and below said concentrates discharge and above said gangue discharge whereby pulp fed to said box will flow counter to the movement of said carrier and below it while flowing to said gangue discharge, said box including means providing an elongated passageway of restricted dimension perpendicular to said carrier which passageway receives feed from said feed passageway and conducts said feed adjacent said carrier as the feed travels toward the gangue discharge at the other side of the box, said coarse gangue chamber being intermediate the ends of said passageway.

3. A magnetic separator including a carrier, a box adapted to receive said carrier and hold water, a magnet assembly positioned above a run of said carrier as it travels through said box, said carrier being operable to move below themagnets of said magnet assembly from one side of said box to the other, a gangue discharge below said carrier and adjacent one side of said box, a magnetic material concentrates discharge below said carrier and adjacent the other side of said box and closely adjacent one end of said magnet assembly, said carrier when in operation moving from said gangue discharge toward said concentrates discharge, said concentrates discharge being above said gangue discharge, and a feed chamber adjacent and directly below' said ,concentrates discharge and also closely adjacent said one end of said magnet assembly whereby the magnetic material derived directly from said feed chamber and attracted by said magnet assembly travels only a relatively short distance before it passes out of the influence of the magnet assembly, said feed chamber being above said gangue discharge whereby pulp fed to said box will flow counter to the movement of said carrier and below it while flowing to said gangue discharge, said box including means providing an elongated passageway of restricted dimension perpendicular to said carrier which passageway receives feed from said feed passageway and conducts said feed adjacent said carrier as the feed travels toward the gangue discharge at the other side of the box.

4. A magnetic separator including a carrier, a box adapted to receive said carrier and hold water, a magnet assembly positioned above a run of said carrier as it travels through said box, said carrier being operable to move below the magnets of said magnet assembly from one side of said box to the other, a gangue discharge belowsaid carrier and adjacent one side of said box, a magnetic material concentrates discharge below said carrier and adjacent the other side of said box and closely adjacent one end of said magnet assembly, said carrier when in operation moving from said gangue discharge toward said concentrates discharge, said concentrates discharge being above said gangue discharge, a coarse gangue chamber below said carrier intermediate said gangue discharge and said concentrates discharge, and a feed chamber adjacent and directly below said concentrates discharge and also closely adjacent said one end of said magnet assembly whereby the magnetic material derived directly from said feed chamber and attracted by said magnet assembly travels only a relatively short distance before it passes out of the influence of the magnet assembly, said feed chamber being above said gangue discharge whereby pulp fed to said box will flow counter to the movement of said carrier and below it while flowing to said gangue discharge, said box including means providing an elongated passageway of restricted dimension perpendicular to said carrier which passageway receives feed from said feed passageway and conducts said feed adjacent said carrier as the feed travels toward the gangue discharge at the other side of the box.

5. A,magnetic separator including a group of magnets of alternate opposite polarities, a carrier movable under said magnets and operable to carry a layer of magnetic material thereon, a feed chamber for feeding a pulp mixture, of magnetic material and non-magnetic material to the lower surface of said carrier adjacent one end of said group of magnets, a magnetic material discharge closely adjacent said feed chamber and ,removed therefrom in the direction of travel of said carrier and adjacent said one end of said group of magnets whereby magnetic material attracted to said carrier by saidmagnets will travel only a short distance before it moves out of the influence of said magnets andis discharged, a non-magnetic material discharge adjacent the other end of said group of magnets and below said carrier and positioned horizontally'below said feed chamber, an elongated thin passageway formed in part by said lower surface of said carrier and extending from said feed chamber to said non-magnetic material discharge whereby essentially non-magnetic material in the pulp flowing from said feed chamber to its discharge will flow in a shallow stream under. the influence of said group of magnets andany magnetic material contained therein will be held against the carrier and returned toward the feed chamber and magnetic material discharge, and a coarse non-magnetic material receiving chamber interposed between the feed chute and nonmagnetic material discharge.

6. A magnetic separator including a group of magnets of alternate opposite polarities, a carrier movable under said magnets and operable to carry a layer of magnetic material thereon, a feed chamber for feeding a pulp mixture of magnetic material and non-magnetic material to the lower surface of said carrier and adjacent one end of said group of magnets, a magnetic material discharge closely adjacent said feed chamber and removed therefrom in the direction of travel of said carrier and adjacent said one end of said group of magnets whereby magnetic material attracted to said carrier by said magnets will travel only a short distance before it moves out of the influence of said group of magnets and is discharged, a non-magnetic material discharge adjacent the other end of said magnets and below said carrier, and an elongated thin passageway formed in part by said lower surface of said carrier and extending from said feed chamber to said non-magnetic material discharge whereby essentially non-magnetic material in the pulp flowing from said feed chamber to its discharge will flow in a shallow stream under the influence of said group of magnets and any magnetic material contained therein will be held against the carrier and returned toward the feed chamber and magnetic material discharge.

7. A magnetic separator including a group of magnets of alternate opposite polarities, a carrier movable under said magnets and operable to carry a layer of magnetic material thereon, a feed chamber for feeding a pulp mixture of magnetic material and non-magnetic material to the lower surface of said carrier adjacent one end of said group of magnets, a magnetic material discharge closely adjacent said feed chamber and removed therefrom in the direction of travel of said carrier and adjacent said one end of said group of magnets whereby magnetic material attracted to said carrier by'said group of magnets will travel only a short distance before it moves out of the influence of said group of magnets and is discharged, a non-magnetic materialdischarge adjacent the other end of said magnets and below said carrier and positioned horizontally below said feed chamber, and a thin passageway formed in part by said lower surface of said carrier and extending from said feedchamber to said non-magnetic material discharge whereby essentially non-magnetic material in the pulp flowing from said feed chamber to its discharge will flow in a shallow stream under the influence of said group of magnets and any magnetic material contained therein willbe held against the carrier and returned toward the feed chamber and magnetic material discharge, said thin passageway being substantially of uniform height and extending a distance at least equal to the distance between two adjacent magnet poles. I

8. A magnetic separator including means providing a magnetic field, a, carrier operable to move from one side of said field to the other and carry magnetic material under the influence of said magnetic field means, means providing a concentrates discharge, means providing a pulp discharge removed from said concentrates discharge opposite tothe direction Of travel of said carrier, a pulp feed chamber adjacent said concentrates discharge and operable to feed pulp to said carrier, a passageway interconnecting said feed chamber and said pulp discharge having said carrier forming one wall thereof, and concentrates washing mechanism in said feed chamber above the liquid level of said feed chamber operable to wash said concentrates and deliver any material removed from said carrier to said feed chamber.

9. A magnetic separator including means providing a magnetic field, a carrier operable to move from one side of said field to the otherand carry magnetic material under the influence of said magnetic field means, means providing a concentrates discharge, means providing a pulp discharge removed from said concentrates discharge opposite to the direction of travel of said carrier, a pulp feed chamber adjacent saidconcentrates discharge and operable to feed pulp to said carrier, a passageway interconnecting said feed chamber and said pulp discharge having said carrier forming one wall thereof, and concentrates washing mechanism in said feed chamber operable to wash said concentrates and deliver any material removed from said carrier to said feed chamber.

10. A magnetic separator including means providing a magnetic field, a carrier operable to move from one side of said field to the other and carry magnetic material under the influence of said magnetic field means, means providing a concentrates discharge, means providing a pulp discharge, a pulp feed chamber operable tofeed pulp to said carrier, and a concentrates wash in said feed chamber operable to wash the concentrates above the liquid level of said pulp feed chamber to remove non-magnetic material therefrom and return it to said pulp feed chamber.

11. A magnetic separator including means providingla magnetic field, a carrier operableto move from one side of said field to the other and carry magnetic material under the influence of said magnetic field means, means providing a concentrates discharge, means providing a pulp discharge, a pulp feed chamber operable to feed pulp to-said carrier, and a concentrates wash in said feed chamber operable towash the concentrates to remove non-magnetic material therefrom and return it to said pulp feed chamber.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,150,628v Stefiensen H May 30, 1939 2,356,463 Linney Aug. 22, 1944 2,564,515 Vogel Aug. 14, 1951 2,597,561 Blind May 20, 1952 2,607,478 Newton Aug. 19, 1952

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