US824893A

US824893A - Magnetic ore-separator.

Info

Publication number: US824893A
Application number: US27253705A
Authority: US
Inventors: Joseph Weatherby Jr
Original assignee: Individual
Current assignee: Individual
Priority date: 1905-08-03
Filing date: 1905-08-03
Publication date: 1906-07-03
Anticipated expiration: 1923-07-03

Description

PATENTED JULY 3, 1906.

APPLICATION FILED AUG. 3, 1905- 6 SHEETS-SHEET 1.

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3110044 606 1,70 J (ya/2 midi/Z6 1 6% Jr.

afloat lmi/h mooeo PATENTED JULY 3, 1906.

J. WE ATHBRBY, JR. MAGNETIC ORE SEPARATOR.

APPLICATION FILED AUG. 3, 1905.

6 SHEETS-SHEET 2.

QWHmeoqw No. 824,893. PATENTED JULY 3, 1906. J. WEATHERBY, JR. MAGNETIC ORE SEPARATOR.

APPLICATION FILED AUG. 3, 1905.

6 SHBETSSHEET 3 Qwvewtoz wi/bneooao J (3/2]! 8 '7 J2. c. W v I No. 824,893. PATENTED JULY 3, 1906. J. WBATHERBY, JR. MAGNETIC ORE SEPARATOR.

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I lkvi/llmeooeo No. 824,893. PATENTED JULY 3, 1906.

' J. WBATHBRBY, JR.

MAGNETIC ORE SBPARATOR.

APPLICATION FILED AUG. 3. 1905.

6 SHEETSBHEET 5.

FEE E w W .57 2X 26 25+ PATENTED' JULY 8, 1906..

J. WBATHERBY, JE- MAGNETIC ORE SBPARATOR.

APPLICATION FILED AUG. 3. 1905.

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aflomwl wi/tvwooeo UNITED sTA rns PA -ENT OFFICE.

JOSEPH WEATHERBY; JR., OF NEW QUMBERLAND, PENNSYLVANIA. A MAGNETIC ORE-SVEPARATOR.

Specification of Letters Patent.

' Patented July 3; 1906.

Application filed August 3, 1905. Serial No. 272,537.

To all whom it may concern.-

Be it known that I, JOSEPH WEATHERBY, J r., a citizen of the United States, residing at v New Cumberland, in the county of Cumber land and State of Penns lvania, have invented certain new and use ul Improvements in Magnetic Ore-Separators and I do declare the following to be a full, clear, and exact descri tion of the invention, such as will enable otiiers skilled in the art to which it appertains to make and use the same.

My invention is an improved magnetic ore-separator adapted to separate ore particles possessing magnetic permeability from gangue particles of no magnetic ermeability and to effect a separation of t e magnetic particles in accordance with the degree of magnetic permeability thereof.

One ob ect of my invention is to effect improvements in the construction and arrangement of the magnet and movable armature elements, whereby a single magnet may be employed with a plurality of such movable armature elements to increase the capacity of the machine and to effect an economy in the o erati'on thereof.

A urther object is to effect im rovements in the construction of the movab e armature elements, whereby the same comprise revoluble armature-rolls which act centrifugally to impart mechanical motion to the ore par A further object'is to provide improved means to adjust such adjustable pole-piece member.v

A further object is to effect such improvements in the construction and arrangement of the magnet pole-piece and movable armature as to provide a downwardly-opening inclined air-gap between them to facilitate the discharge by gravity of the gangue particles, and, further, to combine with such polepiece and movable armature a partition 'which is interposed in the air-gap and in the magnetic field between the pole-piece and tion of particles of minimum magnetic permeability from the gangue particles, and

hence recover such particles of minimum magnetic permeability.

A further object is to combine with the pole-piece of a magnet a movable armature provided on its opposing surface .with localized areas of greater-ma netic efficiency than corresponding areas of the ma et pole-piece to cause loose magnetic partic es in the magnetic field to adhere to such localized areas and be carried by the movement of the armature out of the magnetic field, thus enabling me to dispense with the use of a screen in connection with and between the magnet poleiece and the armature.

A rther object of my invention is to provide inconnection with the magnet polepiece and the movable armature'means to mechanlcall move the particles between them in a p ane at an angle to that of their movement in the lines of force in the magnetic field in addition to the movementof such articleswith the movable armature when eing carried thereby through and out of the magnetic field.

A further object is to effect improvements in the construction of the armature-rolls,

the magnetic fields by the rotation of such rolls.

A further object is to eflect improvements in the construction of the armature-rolls, whereby the same may be caused to become the poleieces of a magnet.

A furt er object is to provide improved 7 means for adjusting the partition-plates interposed in the magnetic fields between the polepieces and the armature-rolls, so that such partition-plates may be moved into such magnetic fields to any desired extent and may be disposed at any desired inclination. A further object is to combine with amagnet pole-piece and a movable armatureelethe; movable armature -to effect the separament means to cause material to liein a IIO layer on the working face of such movable to the armaturea perspective view of a magnetic ore-separattical section view of the same.

ing machine embodying my invention. Fig. 2 is partly a side elevation and partly a ver- Fig. 3 is a vertical sectional view of the same, taken on the plane indicated by the line a a of Fig. 2. Fig. 4 is a detail side elevation of the magnet- Fig. 5 is a detail transverse sectional view showing-the magnet andthe revoluble armature-rolls arranged in operative relation thereto and also indicating the position of the diamagnetic partition-plates with their upper ends interposed in the magnetic fields between the divided pole-pieces of the magnet and armature-rolls. Fig. 6 is a detail view, partly in elevation and partly in section, showing an armature having a pair of rolls which comprise its pole-pieces. Fig. 7 is a detail perspective view of. one of the adjustable members of the magnet pole-pieces, also showing the adjusting-screw which operates the same. Fig. 8 is partly an elevation and partly'a sectional view illustrating a modification in the construction of the armature rolls. Fig. 9.is a top plan view showing the relative arrangement of the armature-rolls and the magnet with which they coact. Fig. 10 is a diagrammatic elevation showing the relative arrangement of the magnet, the'armature-rolls, and a plurality of partitionplates for effecting a permanent separation of the ore particles in accordance with the respective magnetic permeability of such particles. Fig. 11 is a diagram illustrating the magnetic relation between the armature and field-magnet, showing the dense magnetic flux concentrated on the serrations of the armature. i

.In a suitable framework 1 is secured a horizontally-disposed electromagnet 2 which comprises the core 3 and the coil 4. The ends of the core, which is of cylindrical form, project beyond the ends of the coil and are forced into, completely fill, and are firmly se-. cured in correspondingly-shaped sockets 5 in pole-pieces 6. Bolts 7 are here shown to secure the pole-pieces on the ends of the core.

Each pole-piece is hereshown as rectangular I in form, provided on its. upper side with a pair of upwardly-divergin inclined divisions 8, which at each end of t e core are of one polaritythat is to say, the division 8 of one of the pole-pieces 6 will be of positive polarity, while those of the other pole-piece 6 will be of negative polarity. Lugs 9 are also formed on the upper sides of the pole-pieces 6. The divisions 8 and the lugs 9 extend provide improved. long rectangular form, and

lengthwise of the respective pole-pieces from 6 end to end thereof. On the upper side of each pole-piece division 8 is an adjustable' pole piece member 10, which is of obwhich is beveled, as at 11. Guide-bars 12, which are preferably made of steel, are secured on the upper sides of the pole-piece divisions 8, and the adjustable members 10 are provided on their under sides with guidegrooves 13, which are engaged by said guidebars, and the said members 10 are hence mounted for longitudinal movement on the the inner edge of pole-piecedivisions 8, so that they may be.

extended outwardly therefrom to any necessary extent. The said members 10 form prolongations of the polepieces, as will be understood. By the provision of the guidebars and guideooves friction between the divisions 8 and t e members 10 is diminished to facilitate the adjustment of the said members 10. The said adjustable members 10 are provided with slots 14. Bolts 15, which secure the said members to the pole-piece divisions 8, pass through the said slots, the latter, as will be understood, serving to permit the adjustment of the said members 10.

' On the lug 9 of each pole-piece is secured a plate or supporting member 16 of suitable length and width and which is made of brass or other suitable diamagnetic material. Such plates 16 are secured on the said lugs 9 by means of screws 17, and their-outer edges are beveled on their under sides, as at 18, and bear against the adjustable pole-piece members 10. To adjust the said members 10, I

provide vertically-movable wedge-cams 19,

which bear against and are guided by the sides of the lugs 9 and the inclined camwedges of which engage similarly-shaped cam-recesses 20 in the adjustable pole piece members 10. The said wedge-cams are provided with screws 21 and adjusting-nuts 22, which bear on the said -plates. ing the nuts to raise the screws and cam- By turn- IIO wedges the movable pole-piece members 10 may be moved outwardly to project beyond the pole-piece division 8, assuming. that the bolts 15 have been first loosened. By lowering the cam-wedges 19 to release the adjustable pole members 10 the latter willby their own gravity move downward and inwardly on the pole-piece divisions 8. The electromagnet is here shown as secured to and sup- 1 ported in the frame by means of screws 23,-

which enter openings 24 the pole-pieces 6'. Above and on opposite sldes of themagnet are pairs of rolls 25, which form the -pole-' pieces of armatures, as hereinafter described. The members of each pair'of rolls 25 are secured on the ends of a core 26, which is here shown as the core-piece of an electromagnet, the coil being shown at 27 at a point between the pair of roller pole-pieces and commutator rings or disks being indicated at '28. ,Hence by sendin current through the coil 27 theto supply current to the coil 27, and hence I prefer to employ the term armature-rolls as most appropriately designating. the function and relation of the said rolls 25, since they act as armature pole-pieces with reference to the magnetic pole-pieces and also act as rollers to impart mechanical motion to the ore particles. It will be observed by referenceto Fig. 6 that the rolls have their ends hollowed and have their intermediate solid portions 29 counterbored, as at 30, to receive the ends of the cores 26. The ends of the cores 26 are provided with short screw-threaded extensions 31 which are screwed into correspondi'ngly-threaded openings in the centers of the armature-rolls. Journal members 32 for the cores 26 and the armature-rolls have their inner ends screw-threaded reversely to the threads on the core extensions 31 and screwed into the said threaded openings in the center of the armature-rolls, the

. inner ends of the said journal members abutting against the extensions of the cores 26. Collars 33 are secured on, the journal members, as by means of dowel-pins 34, and fit counterbores 35 in the solid intermediate portions of the armature-rolls. Said collars are secured to the armature-rolls by'screws 36 and engage the outer ends of the dowel-pins 37, which extend throu h openings in the intermediate portions of t e armature-rolls and enter corresponding-openings in the ends of the cores 26. The said journal members 32 of the shafts and armature-rolls are mounted in bearings 38, with which the frame 1 is pro tion with a plurality of revoluble armaturerolls, one opposed to each division of each pole-piece of the magnet, so that I may be enabled to employ only a single magnet in operative relation to a plurality of armature rolls, thus greatl increasing the capacity of the machine an effecting a material economy in the cost of the operation thereof. It

will be understood that in those cases in which current is supplied to the coils 27 and the armature-rolls become pole-pieces of revoluble magnets the olarity of each roll will flbe the opposite of t at of the magnet polepiece to which it is opposed. The peripheries of the armature-rolls are screw-threaded, as at 39, to provide serrations which form It is only when re-.

osing localized areas of the flattened suraces of the field pole-pieces, so that the loose magnetic particles in the magnetic fields or air-gaps between the pole-pieces and the armature-rolls will be caused to leave the polepieces and adhere to the serrations of the armature-rolls and by the rotation of the armature pole-piece rolls be carried out of the said magnetic fields.

Substantially mounted on the frame 1 and at both ends of the armature pole-pieces 25 are the end guards 4], preferably made of wood or other diamagnetlc substance. These end guards fit close to the ends of the polepieces and are of a greater diameter, thus allowing space between the pole-faces and the shields 40. on the inner side of each armature is a semicylindrical shield-plate 40, substantially secured to the end guards 41 by screws. At the base of each of said shieldplates is an opening in which is placed a removable guard 42, preferably made of wood, and so disposed as to tightly close the opening thus formed between the shield-plates and the supporting member 16. The said removable guards when removed from the said openings enable the outer edges of the adius'table pole piece members 10 to be sighted, thus greatly facilitating the adjusting of the adjustable pole-piece members and enabling them to be set at the required distance from the armature poles. On the outer side of each armature-pole is a substantially semicylindrical shield plate 43, secured to end guards 41, the base of which forms a jamb for'the hinged board 44, which is in turn hinged to a door 45, that is normally secured in a closed osition by means'of a bolt or other suitable ocking device 46; On the inner side of each door and fastened to the frame 1 are horizontally-disposed supporting guide-bars 47, on which'are laterally-movable brushes 48, which bear against the peripheries of the armature pole-pieces and the bristles of which are held in contact with the armature-poles by the action of s rings 49, here shown as coil-springs, whic are fastened at one end to the heads of the brushes and' at the other end bear against the doors 45. The hinged boards 44 also act as guides for the brushes. When the doors 45 and the hinged boards 44 are opened, the brushes 48 are exposed and can be readily removed or replaced- Above each 'armature-roll is a feed-roll 50.

Each of said feed-rolls has its shaft 51 j ournaled in bearings 52, Which depend from secondary hoppers 53, that are supported by the I cured to the journal end late 52. Sightshown as provided each at one framework 1, as shown. The inner inclined lower side of each secondary hopper is provided with a concave guard-brace 54, disposed at a slight distance to one side of the. u per portion of the feed-roll of such hopper.

gaged by a screw 59, which has its bearings 60 61 secured on said plate. Said screw is geared to a hand-wheel 62 by means of mitergears 63, the shafts of said hand-wheels being ournaled in the said bearings 61. Each .feed-roll is inclosed in a casing comprising a substantiall semicircular inner member 64, secured to t e concave guard-base and to the journal end plates -52, and a substantially semicylindrical outer member 65, also se- 0 enings95 are formed at. t e upper sides of t e said outer members. The secondary hop ers, each of which su plies material to the eed roll above one of the armature-rolls, are supplied with material froma masterhopper, bin, or other compartment (not shown) which is located abovethe secondary hoppers and is provided with feed-pipes 66, which extend ownwardly into the upper ends of the second ar hoppers. Material flows from the master-hopper to the secondary hoppers through the said feed-pipes 66 until the lower ends of the said feed-pipes become closed by the accumulation of material in thesaid. secondary hoppers, and the supply to the said secondary oppers ceases until enough material has been discharged therefrom onto the feed-rolls to cause the lower ends of the feed+pipes to be uncovered. Hence the secondary hoppers are kept automatically'supplied with material so long as there is such material in the masterhopper, and the secondary hoppers areprevented from overflowing.

' Under the pole-pieces of the magnet 2 are hoppers 67 for. the reception of the gangue. On the outer sides of the said ho pore-67 are hoppers 68, of which there-may be any suitable number, for the reception of the concentrates or ore particles separated from the gangue by the action of the magnet and the armature-rolls, as hereinafter stated. Un-

der each armature-roll is an inclined uiamagnetic partition dplate or chute 69, which is longitudinally sli ably mounted on the ivot- I lly-supported member 70. One of sai supporting members 70 is here shown as pivotally mounted on one side of the hopper 67, as at 71. Each partition-plate has a set-screw 72 to secure it to the supporting member 7 O at any suitable adjustment, and each supporting member 70 has a supporting-link 73,

the said ,mature-rolls or to be thin sheet or film onto the upper pivotally connected thereto and rovided with an adjusting-slot 74, throug which asses a set-screw 75, employed to secure the ower portion of the link to one wall of one of the hoppers 68. The slots 74 and screws 75 permit such adjustment of the links as is required to secure any desired angular adjust: ment of the supports 70 and partition-plates 69, so that the latter may be disposed at any required inclination. It will'be observed by reference to the drawings, particularly Figs. 2 and 5, that the upper ends of the partitionplates 69 are interposeddirectly the magnetic fields between the divisions 8 of the pole-pieces and the armature-rolls and that lates 69 may be adjusted so as .to dispose t eir up er ends to within a very short distance ot the adjustable pole-piece members 10 or to adjust them somewhat more remotely from said adjustable pole-v piece members, as ma be required by the character of the material treated.

The shafts of the armature-rolls are herev end with a bevel-gear 76, which bevel-gears are en by similar gears 77 on the power-sha t 78, which. has its bearings 79 secured on suitable supports 80 at one end of the frame 1. Said power-shaft is here shown as provided with a ulley 81, whereby it may be rotated b a belt 1n order to drive the armatures... he latter revolve in the direction indicated by the arrows in Figs. 2 and each feed-roll is provided on its inner end with a loose pulley 82 and a fast pulley 83. Crossed belts 84 are driven by the cores 26 of the armature-rolls and may be shifted to either the fast pulleys or the loose pulleys to cause the feed-rolls to rotate reversely with reference totheir respective companion ar- Belt-shifters 85 are here shown to thus shift the said belts. In practice in a machine having arin'atures sixteen inches in diameter said armature-rolls have been driven at a rate of from one hundred and fifty to about two hundred revolutions per minute, according to the material treated.

The operation of I lows: The ore to be treated by my improved magnetic ore-separator must its ate is appropriately opened, the rotation of t e roll causes the ore to be delivered in a side of the revoluble armature-roll below the feed-roll. The armature pole-piece roll as it revolves carries the material to the magnetic field or air-gap between the pole-piece 8 and adjust-' able pole-piece member 10 and the portion of the armature-roll'which is opposed thereto. The motion and' centrifugal orce of the armature-roll cause mechanical motion to be 'set up in the ore between the pole-piece and aged 5. The'shaft 5.1 of

thrown out of gear.

my invention is as fole first ground, but need not be roasted. "The ore m each hopper 53 rests upon the feed-roll 50. When its adjustable member and the armature-roll, which mechanical motion of the ore particles facilitates the separation of the gangue, which has not magnetic permeability, from those particles which have ma netic permeability and which are capable 0% magnetic saturation to a greater or less degree. Owing to the provision of the spirall -arranged serrations on the periphery of t e armature-roll, the ore in the magnetic field is also moved mechanicall and angularly with respect to the lane of magnetic movement thereof in the 'nes of force in the magnetic field, which angular motion of the ore particles further facilitates the separation of the gangue particles from those possessin magnetic permeability. That portion of t e magnetic field is stronger between the carrier armature-roll and the magnetic ole extension than that portion which is etween said roll and the opposing face of the pole-piece 8. The magnetic action of the roll and extension 10 causes the material to la somewhat as it passes between them, so t at some slip occurs at this point between the material and the roll which increases the mechanical action of the spirally-disposed serrations on the roll and sets up sucha scouring action beare saved and separated from the gan e.

tween the particles of the material as to cause a much lar er percentage thereof to finally adhere to the roll and be carried out of the ma netic field thereby than would otherwise be t e case. It will be observed that the polepiece presents an inclined surface under the armature-roll and coacts with the latter to form an inclined downwardlyopening airgap between them, which permits the particlesof gangue to drop from the adjustable pole-piece member 10 onto the inclined face of the pole-division 8 opposite to the armature while still in the magnetic field and from said inclined face into the hopper 67. Those ore particles which have ma netic permeabilit in any degree, owing to t e provision of the ocalized areas of greater magnetic efficiency formed by the serrations on the periphery of the armature-roll and on the wedge terminations of which the lines of force accumulate, leave the gangue particles and are caused to adhere to the armatureroll and are carried by the rotation of the armature-roll beyond the upper edge of the partition-plate 69. Such ore particles as possess only very slight magnetic permeability drop from the-armature-roll while yet in the magnetic field and are directed by gravity from the plate 69 into the hopper 68 and Such particles hence are saved becauseo the disposition of the upper portion of the partition plate in the magnetlc field. Such particles as possess a greater magnetic permeability adhere to the armature-roll for a greater lengthof time and are carried by the said roll farther before they drop therefrom by the so that the constituent elements of the material are divided and separately discharged by the action of the armature-roll in accordance with the res ectiv'e magnetic permeability of such partic es. By the provision and employment of a plurality of suitably-s .aced partition-plates under the armature-r0 ls the particles thus separated by the armaturerolls in accordance with the extent of their magnetic permeability may be kept permav nently separated. I have shown such a plurality of partition-plates in Fig. 10, the primary plate being indicated at 69 and the others at 86. The brushes 48, which bear against the armature-rolls, prevent anymagnetic'particles of hi h magnetic permeabilityfrom be-. ing carried round and round by such rolls. The function of the shields which cover the feed-rolls and the armature-rolls is to prevent material from being thrown centrifugally from said rolls, an additional funct on eing to dispose the material on the working sides of said rolls in a thin layer and to also prevent dust from escaping.

In Fig. 8 I show a modification in the construction of an armature-roll in which the pe-' ripheral faceof the same is composed of a plurality of annular disks 87 88 of unequal diameter, the disks 88 being the larger and disposed alternately on the periphery of the roll secured together by bolts 89, which pass therethrough and also pass throu h heads 90, which are secured on the ends 0 the roll by screws 91. e

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is 1 v. 1-. In a magnetic ore-separator, a relatively fixed magnet having a divided pole piece of one polarity, in combination with a plurality of movable armatures each in operative relation to one of the divisions of the said pole-piece.

2. In a magnetic ore-separator, a relatively fixed magnet having a divided polepiece of one polarity, incombination with a IIO i of said pole-piece also presenting an inclined surface and forming a shoulder, a moving magnetic carrier element presenting a surface above said pole-piece and extension andforming an inclined air-(giap between them, and a partition interpose directly in the broadened portion of the air-gap between the polepiece and the carrier element and behind the shoulder formed by the pole extension.

4. In a magnetic ore-separator, the combination of a magnet having a pole-piece presenting an inclined surface, and an extension 'of said pole-piece also presenting an inclined surface and forming a shoulder, ,a moving magnetic carrier element presenting a surface above said pole-piece and extension and formthe s revolving magnetic carrier element present- 3O ing an inclined air-gap between them, and a plurality of partitions to catch the magnetic particles dropped by the carrier, one of said partitions being interposed directly in the broadened portion of theair-gap between the pole-piece and the carrier element and behind oulde'r formed by the pole extension.

5. In a magnetic ore-separator, the com-' bination of a magnet having a pole-piece presenting an inclined surface and an extension of said pole-piece also presenting an inclined surface and forming a shoulder, a cylindrical a surface above and moving past said pee-place and extension and forming an'inclmed air-gap between them, and a partitioninterposed directly in the broadened portion of the air-gap between the pole-piece and the carrier element and behind the shoulder formed by the pole extension 6. In a magneticore-separator, the combi-.

nation of a magnet having a pole-piece pre- 1 senting an inclined surface and an extension of said pole-piece also presenting an inclined surface'and forming ashoulder, a cylindrical also at an angle to the plane of movement'of revolving magnetic carrier element, presenta surface above and moving past said po e-p1ece and extension and forming an airgap between them, means to feed materialin a thin layer to the airap, and means to subject such material, w e its movement through the air-gap is magnetically retarded,

to force exerted in a direction at an angle to the lines of magnetic force in the air-gap and such material with the carrier.

senses luble armatures having cylindrical poles each disposed op osite one of the magnet-pole divisions and having peripheral serrations, for the purpose set forth.

9. In a magnetic ore-separator, the combination of a fixed magnet comprising a core, a coil on the intermediate portion and later ally-extending pole-pieces on the ends thereof, with a revoluble armature comprising a core and cylindrical pole-pieces on the ends thereof, and opposed to the pole-pieces of the magnet, substantially as described. 10. In a magnetic ore-separator, the combination of a magnet having a plurality of radially-disposed, fixed pole-pieces,- one tween the others, aplate of-non-magnetic material on the intermediate pole-piece and extending in opposite directions therefrom, ad-

justable pole extensions on the outer fixed ole-pieces, armatures presenting moving suraces op osed to and spaced from the outer fixed po e-pieces and the adjustable pole extensions, and means carried by the said plate to adjust said pole extensions, substantially as described.

11. In a magnetic ore-separator, the combination of a magnet having a plurality of radially-disp'cised, fixed pole-pieces, one between the others, aplate of non-magnetic material on the intermediate poleieces and extending in opposite directions 1; erefrom, ad-

justable pole extensions on the outer fixed ole-pieces, armatures pre'senting'moving surfaces op osed to and spaced from the outer fixed po e-pieces and the adjustable pole extensions, and means to adjust said pole extensions, substantially as described.

12. In a magnetic ore-separator, the com- I bination of a magnet having a plurality of radially-disposed, fixed pole-pieces, one between the others, aplate of non-magnetic material on the intermediate pole,- ieces and extending in opposite directions t erefrom, adjustable pole extensions on the'outer fixed ole-pieces, armatures presenting moving suraces op osed toand spaced from the outer fixed po e-pieces and the adjustable ole extensions, and wedge-cams carried by said plate and bearing against the intermediate pole-pieces to adjust said pole extensions, substantially as described.

13. In a magnetic ore-separator, the com bination-of a magnet, an adjustable pole-piece said adjustable pole-piece, asupporting member, a shield dlS osed in proximity to and spaced from sai armature and also spaced from said sup orting member to form an opening throug which the end of the poles piece resented to the armature may be observe and a removable guard to close such openinlg,1 substantially as described.

14. r a magnetic ore-separator, the combination of a magnet having a plurality of for such ;Inagnet, an armature presenting a -moving surface opposed to and spaced from pole divisions at each end and a plurality 'of board hinged to the door and covering the revoluble armatures having cylindrical poles, brush when closed a ainst the shield, subeach disposed opposite one of the magnetstantially as described. pole divisions, substantially as described In testimony whereof I have hereunto set 5 15. In a magnetic ore-separator, the commy hand in presence of two subscribing wit 15 bination of a magnet, an armature havin a nesses.

revoluble cylindrical pole-piece, a shield or JOSEPH WEATHERBY, JR. said pole-piece, a hinged door, guides, a brush Witnesses: movable on the guides, a spring to press the DONALD HOYER,

Io brush against the armature pole-piece, and a J. C. DELANEY.