US 463305 A
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3Sheets-8heet 1. W. D. HOFFMAN.
No. 463,305. Patented Nov. 17, 1891.
(No Model;) 3 Sheets---Sl1eet W, D. HOFFMAN.
ORE SBPARATOR. I No. 463,305. Patented Nov. 17, 1-891.
l (No Model.) 3 Sheets-Sheet 3.
W. D. HOFFMAN.
ORE SBPARATOR. 1
No. 463,305. Patented'Nov. 1.7, 1891.
VII/4 0000 O O 0 O O 0- .rV miP l I flizess 5+ UNITED STATES PATENT QEFICE.
XVILLIAM DURANT HOFFMAN, OF BREXVS"ER, NElV YORK.
ORE-S EPARATO R.
SPECIFICATION forming part of Letters Patent No. 463,305, dated November 17, 18191.
Application filed July 15,1891. Serial No. 399,577. (No model.)
To all whom it may concern:
Be it known that 1, WILLIAM DURANT HOFFMAN, of Brewster, in the county of Putnam and State of New York, have invented a new and useful Improvement in Magnetic Separators, of which the following is a specification.
My invention relates to an improvement in magnetic separators in which a preparatory or stratifying magnet is arranged to act upon the mass of material at a point intermediate of the feed and the means for effecting the final separation.
In separating ore in large quantities by magnetism it has been found that on account of the thickness of the mass or layer delivered to the action of the magnets and carried through the magnetic field, thereby bringing the magnetic particles nearest the magnetic poles within a stronger magnetic field than the outside portion of the mass, the mag netic force sufficient to insure the separation of the magnetic particles nearest the surface is not strong enough to cause an attraction and separation of the magnetic particles farthest from the magnetic poles, and a loss thereby ensues. On the other hand, if the magnetic field is made strong enough to attract themagnetic particles farthest from the poles it is then sufficient to hold the lean or slightly-magnetic particles nearer the poles with sufficient force to carry them through the magnetic field without releasing, and thereby prever t a complete separation. These objections are especially marked in separators Where the magnetic particles are picked out of the mass against the action of gravity, in separators which employ a revolving drum or vertical or inclined belts as conveyors, and in separators where the material is brought into actual contact with the magnetic poles.
The object of my present invention is to overcome the above-named objections and to provide a magnetic separator which will effect the complete separation of a great mass of material, so that the resultantproduct-s of the separation may be classified with great nicety.
A practical embodiment of my invention is represented in the accompanying drawings,
11 whiclr- Figure 1 is a view of the separator in vert-ical longitudinal section, the magnets being shown in end elevation. Fig. 2 is a top plan view; and Fig. 3 is a View in detail, showing the drum for conveying the material within the field of the curved line of the magnets and the parts in immediate contact therewith.
A represents the supporting-frame, having hinged at one end the auxiliary frame a, the latter forming a support for the drive-shaft The hinged connection of the frame a with the frame A is shown ate, and the means for holding the frame (tin the desiredadjustment with respect to the'frame A consists of a screw T, pivotally secured to the frame a. and provided with suitable adjusting-nuts t at the point whereit passes through a stationary portion a of the main frame A. The drive-shaft v is mounted in suitable bearings b, and has fixed thereto a drive-pulley R, by means of which motion is communicated to the shaft Q) from a source of power not shown. The shaft n is also provided with a loose pulley R, located in proximity to the pulley R for the purpose of shifting the belt to throw the machine out of action. The said shaft '2; has fixed thereon a drum or pulley B for the support at one end of an'endless-belt carrier D. The opposite end of the belt-carrier D is supported upon a drum C, loosely mounted upon a hollow shaft 2', supported in suitable hangers or standards a, fixed to the main frame A. The supports 0 are preferably formed in half-sections which embrace the 0p-&5h
posite sides of the hollow shaft 1?, and are adapted to be drawn firmly together to clamp the shaft between them by means of belts (Z, which in the present instance also serve to hold the support 0 firmly to the main frame A. The shaft t' is preferably provided with bearing-collars m, on which the bearings m, fixed in the ends of the drum C are seated.
The tension of the belt D may be maintained, as desired, by swinging the auxiliary frame a toward and away from the drum C by means of the adjusting-screw T.
A feed-hopper E is fixed to the supportingframe A in position to feed the material to be separated upon the belt near the drum B, a chute F being hinged to the base of the hopper and resting at its free end upon the belt for the purpose of receiving the material from the bottom of the hopper and distributing it in an even layer across the face of the belt. This chute also serves to seal the air-blast. An adjustable gate Q serves to determine the amount of opening at the base of the hopper, and hence the rapidity of feed.
A casing Y, spaced from the belt, extends from the hopper E to a point 'beyond the drum 0, and thence downwardly at the end of the machine and along beneath the drum 0, forming together with the belt a substantial inclosure for the passage of the material to be separated from the time it leaves the chute F until it is finally separated.
Partitions L, M, and N, located at intervals within the casing Y between it andthe belt, serve to determine the size of the passage in proximity to the belt to cutoff such portions of the material as may be desired. The portions of the said partitions L and M nearest the belt are hinged, so that they may be swung toward and away from the belt, and the several partitions L, M, and N are further provided with sliding sections 7', s, and if to further determine the points of separation. The partition N, which forms the final separation of the highest grade from the inferior-grade of material, is supported upon a slide 19, which moves on ways P. The lower ends of the spaces separated by the partition L are provided with gates S and S, which are held normally closed'by means of weights WV and IV, here shown as supported in sliding adjustment upon arms to w, and intended to hold the gates closed under such tension that there will always remain in the vbottom of said spaces in proximity to the gates a mass of material sufficient to seal the gates against 7 the entrance of any considerable amount of air, and at the same time be subject to be opened to allow the discharge of the material when the mass of a predetermined weight has accumulated therein.
Intermediate of the point Where the material is fed upon the belt and the point where the finishing of the separation takes place around the periphery of the drum 0, I locate a magnet H, which may be either a permanent magnet or an electro -magnet, in the present instance shown as an electro-magnet. The magnet I-I consists of a connected series of poles Z, each alternate pole being the opposite polarity of that adjacent thereto, the said magnet being located in proximity to the under side of the belt D.
WVithin the drum 0, I locate a magnet I, which, like the magnet II, may be either permanent or electro, in the present instance shown as an electro and consisting of a series of poles 0, radiating from a center toward the periphery of the drum 0 and located in proximity thereto. In practice I prefer to extend the series of poles 0 a little more than one-half of the distance along the periphery of the drum 0. The poles of the maget I, like those of the magnet II, are arranged so that each alternate pole shall be the opposite polarity to one adjacent thereto. The magnet I is supported upon a suitable frame which is here shown as having a removable half-section j, adapted to partially embrace the hollow shaft t' and serve, together with the framej, to clainp the magnet I in the desired rotary adjustment upon the shaft 1. The said magnet I may also be adjusted within the drum 0 by the rotation of the entire shaft 1' within its supports 0.
' The hollow shaft t' serves as a convenient housing for the wires which lead to the magnet -I, and it is further provided with a central partition X transverse of its longitudinal axis and is perforated upon opposite sides of said partition, as shown at so, and has one of its ends connected with an air-exhaust conduit n. The air-exhaust conduit n also communicates with a chamber G, which by means of a sliding gate or valve K opens communication into the space between the casing Y and the belt, so that when a suitable exhaust mechanism of any well-known or approved form (not shown herein) exerts an exhaust through the conduit n and the gate K is open it will draw a blast of air between the partition M and the face of the belt, and thence upwardly between the partition L and the face of the belt in the opposite direction from that in which the beltD is traveling, and will at the same time draw a current of air into the open end of the shaft 7 and thence outwardly through the openings 00 into the space within the drum C, thence through the open-' ings m upon the opposite side of the partition X, and through the end of the shaft connected with the conduit 12.
It is obvious that air might be forced through the shaft 71 by a blower, instead of being drawn through by an exhaust-er. g
The current of air along the outer surface of the belt D performs a cleaning and scour- ICC vided with marginal ribs 9 to prevent the material from escaping from its edges.
- The operation is as follows: The belt D, having been set in motion in the direction indicated by the arrows, an upward current of air along the periphery of the drum 0 having been established by the exhaust mechanism and the electro-magnets having been energized, the material to be separated is allowed to pass from the hopper E onto the chute F, and is fed thence upon the belt D, which carries it along within the field of the magnet H. As the said material comes within the field of the magnet H, the particles subject to magnetic influence are attracted toward the nearest pole and at the same time are carried alon gby the belt pastthe succession of opposite poles. As the said particles pass the successive poles of the magnet they do 'not follow the line parallel with the belt D, but assume positions under the influence of the magnetic lines of force, which arein the forms of curves from the end of one pole to the end of the nearest pole of opposite polarity. The degree of curvature will depend upon the strength of the magnetic force and the distance between the poles of opposite polarity. By following these curves and at the same time being moved along by the belt the material to be separated assumes a rising-and-falling or wave-like motion. This motion results, first, in the gathering together of the magnetic particles from the mass by their attraction for each other and by the force tending to draw them toward the nearest magnetic pole and consequently nearest the belt, and, secondly, in tending to bring particlesof greatestspecific gravity nearest to the bottom of the mass on the belt D, and consequently nearest the poles of the magnet. The above-described wave like motion causes an expulsion of the slightly-magnetic or non-magnetic material and that of least specific gravity toward the top of the mass on the belt, and results finally in a stratification of the substance to be separated, the most magnetic and heaviest portions being brought closest to the belt and-the lighterand non-magnetic or slightly-magnetic particles farthest from the belt. The jigging motion or violent agitation of the particles of the mass of material, as above described, re-
sults in an effective scouring, action, which tends to clean their surfaces and thereby free them from such impurities as slightly adhere to themas, for example, phosphorus or silica in the case of magnetic iron ore. These nonmagnetic impurities thus freed are expelled from the magnetic portions of the mass by the above-described action and arrange themselves in the stratum farthest from the belt. In such a stratified condition the mass to be separated passes from the field of the magnet II into the field of the magnet I. As the belt follows its path around the periphery of the drum C, the mass justbefore leaving the horizontal line of the belts motion enters the field of the magnet I and the magnetic particles once more assume the directions of the line of force in curves from one pole to its nearest opposite pole. In the form in-which I have represented the magnet I, the poles 0 being farther apart than the poles Z of the magnet H, the curves which the magnetic particles assume will be less sharp. The magnetic particles having been arranged by the preparatory magnet H into a stratum in proximity to the surface of the belt, it becomes feasible to employ a magnetic force sufficiently strong to act upon the entire stratum of partially-separated magnetic particles. The non-magnetic and lighter particles forming the upper stratum will, under the horizontal motion imparted to them by the belt, leave the magnetic stratum in a trajectory as the belt begins to follow around the periphery of the drum 0, and will be assisted in separating itself from the magnetic stratum by the lifting and wedging action of the upward current of air following along between the periphery of the drum O andthe upper portion of the partition -L. Just what part of the upper stratum shall be allowed to finally escape and be permanentlyseparated from thelower stratum is determined by means of the par tition L and its sliding section 0'. Such por tion as passes over the section 0 falls to the base of the space between the casing Y and the partition L, and as it accumulates in a sufficient quantity automatically opens the gate S and escapes. The magnetic stratum follows the path of the belt D around the periphery of the drum O by reason of the at traction to the magnet I and its wave-like motion is continued, constantly gathering the more highly-magnetic particles closer to the poles and consequently to the belt D. This wave-like motion also continues to expel to the surface all the slightly-magnetic substances which gradually fly. from the surface under the centrifugal force and as the mass passes the transverse horizontal axis of the cylinder, being aided by the force of gravity. During its passage around the periphery of the drum C a scouring action is kept up upon the surface of the mass by the opposing current of air and by the agitation of the mass, which effectually brings all of the particles into contact with the air-current. The intensity of the air-current may be regulated by the speedof the exhauster and by the adjustments of the several slides in the partitions. The slightly-magnetic particles, together with such non-magnetic particles as were not at first separated from the mass,fall from the surface of the belt into the space between the partitions L and M,and as they accumulate in sufficient quantitiesare automaticallydischarged through the gate S. After passing the partition M the less magnetic material continues first to fall from the belt, while the more-magnetic is still carried forward and finally leaves the belt after the latter has carried it beyond the holding force of the last pole of the magnet I. The adjustable partition N serves to separate this last mass of material as it falls from the belt, so as to retain a predetermined percentage of purity in that portion which is the most magnetic.
It will be observed that the action of the magnet II is solely that of stratifying or separating the material into layers, together with the resultant scouring, as set forth, while the finishing is performed by the second magnet, which segregates the material forming each layer.
It is obvious that a furthercleaning and separating might be effected,'if found desirable, by locating a magnet similar to the mag net H in proximity to the lower portion of the belt D, so as to hold the magnetic stratum within its field as it leaves the last pole of the magnet I, and that the position of the preparatory or stratifying magnet H may be varied in its position between the feed and the finishingm'iagnet I, as may be desired.
What I claim is 1. In a magnetic separator, mechanism for completing the separation, a stratifying-magnet located in advance of the completing mechanism, and means for conducting the material to be operated upon within the field of the stratifyingmagnet, substantially as set forth.
2. In a magnetic separator, a feeding device, a finishing-m agnet, a stratifying-magnet located intermediate of the feed and finishing magnet, and means for conducting the mateterial to be operated upon successively within the fields of the stratifying and finishing magnets, substantially as set forth.
In a magnetic separator, a feeding device, a finishing-magnet, a stratifying-magnet located intermediate of the feed and finishing magnet, and an endless-belt carrier for conducting the material to be operated upon within the fields of the stratifying and finishing magnets, substantially asset forth.
4. In a magnetic separator, the combination, with an endless-belt carrier, means for feeding the material to be operated upon onto the belt, and mechanism for completing the separation, of a stratifying-magnet located intermediate of the feed and finishing mechanism and comprising aseries of poles of opposite polarity located in proximity to the belt,
substantially as set forth.
5. The combination, with an endless-belt carrier and means for feeding the material to be operated upon onto the belt, of a stratifying-magnet and a finishing-magnet, each comprising a series of poles of opposite polarity and arranged to act successively upon the material as it passes along the belt, substantially as set forth.
6. In a magnetic separator, the combination, with anendless-belt carrier and a separating-magnet located in proximity thereto, of drums forming supports for the opposite ends of the carrier, and a swinging frame in which one of said supporting-drums is mounted, and means for adjusting the frame and hence the drum toward and away from the opposite drum to determine the tension of the belt, substantially as set forth.
7. The combination, with the separating- Inagnet arranged in curved form and the hollow perforated shaft at the center of the curved magnet, of the partition within said hollow shaft and means for directing a current of air through the shaft for cooling the magnets, substantially as set forth.
8. The combination, with the separatingmagnet and the endless-belt carrier extending in proximity to the magnet, of the casing spaced from the endless-belt. carrier to form an air-conduit between" the two, and the feedchute hinged to its support and resting with its free end upon the belt for distributing the material evenly upon the'belt and sealing the air-conduit at the feed end of the casing, substantially as set forth.
9; The combination, with the separatingmagnet arranged in curved form, the hollow shaft at the center, and the endless-belt carrier in proximity to the curved magnet, of a conduit for the air in proximity to the outer face of the belt, an air-chamber, an adjustable gate for opening and closing communication between the chamber and the air-conduit in proximity to the belt, and an exhaustconduit in communication with the air-chamber, substantially as set forth.
WVILLIAM DURANT HOFFMAN.
FREDK. HAYNES, GEORGE BARRY.