US2446813A - Magnetic concentrate washing means for submerged belt magnetic separators - Google Patents

Description

Aug. 10, 1948. R. E. CROCKETT 2,446,813

MAGNETIC CONCENTRATE WASHING MEANS FOR SUBMERGED BELT MAGNETIC SEPARATORS Filed June 24, 1944 27; ,m'flffmi iiiiiilllllliiiiifi -5 uvwsuroa M M A RA/EYS.

'middlings from the belt.

Patented Aug. 10, 1948 MAGNETIC CONCENTBATE WASHING MEANS FOR SUBMERGED BELT NETIC SEPARATORS MAG- Robert E. Crockett, Upper Montclair, N. J., assignor to Dingo Magnetic Separator 00., Milwaukee, '18., a corporation of Wisconsin Application June 24, 1944, Serial No. 541,952

The present invention relates generally to improvements in the art of separating mixed materials having difierent characteristics, and relates more particularly to various improvements in the construction and operation of machines for effecting automatic separation of magnetic material from non-magnetic substances.

The primary object ofmy invention is to provide an improved magnetic separator which is simple in construction and efficient in operation.

When separating granules of magnetic ore from a granular mixture of tailings, middlings and ore particles, it is a relatively simple matter to remove the tailings from the middlings and concentrates, but considerable difliculty may be encountered in effecting final separation of the concentrates from the middlings. Such magnetic separation has heretofore been accomplished with machines of the type shown and described in my copending application Serial No. 365,183, filed November 11, 1940, now Patent No. 2,410,601, dated November 5, 1946, wherein the mixture of magnetic and nonmagnetic particles is conveyed by a. moving belt through one or more liquid basins and from thence through a final washing and separating space extending at an oblique angle upwardly away from the basins and which is subjected to relatively strong magnetic influence. In this prior machine, the mixture of middlings and concentrates which is carried by the belt into the final separating space, is subjected to the washing action of a multiplicity of discrete and forceful jets of liquid which are projected across the space and against the layer of material being held against the travelling belt by magnetic force, and these jets have a tendency to gouge or plow into the layer thereby dislodging concentrates as well as In order to reclaim these concentrates, the fin al washing space or zone is limited in height so that all portions thereof are subjected to the strong magnetic influence, and the dislodged concentrates are thus quickly returned to the conveying surface of the belt. Most of the middlings which are removed from the belt by the forceful jets of washing liquid, 4

however, remain within the strong magnetic field and a substantial portion of these middlings are also immediately recaptured by the belt with the returning concentrates, thus resulting in the production of final concentrates containing a considerable quantity of middlings.

It is therefore a more specific object of my present invention to provide improvements in magnetic separating machines of the above described general type, wherein more efiective automatic 14 Claims. (Cl. 209-225) separation of the magnetic and non-magnetic ingredients of a granular mixture, may be accomplished,- and purer concentrates are thus obtained.

Another specific object of this invention is to provide a simplified and more reliable magnetic ore separating system, wherein the product is most eiiectively subjected to gentle final washing and cleansing without introducing excessive loss of magnetic particles.

A further specific object of the invention is to provide improved instrumentalities for effecting delivery of washing liquid to the final separating and cleansing space or zone of a magnetic separator, and for insuring prompt removal of the non-magnetic ingredients from the washing space.

Still another specific object of my invention is to provide various improvements in the construction and operation of endless belt magnetic separators whereby the structures are simplified and the operating efficiency is enhanced to a maximum.

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

A clear conception of a typical embodiment of my present improvement and of the normal functioning thereof, may be had by referring to the drawing accompanying and forming a. part of this specification wherein like reference characters are employed to designate similar parts in the various views.

Fig. 1 is a. somewhat diagrammatic and part sectional side elevation of a typical magnetic separator embodying the invention;

Fig. 2 is an enlarged top view of the pan or trough which cooperates with the conveyor belt to provide the final separating and washing space, with the water jet deflector omitted;

Fig. 3 is a similarly enlarged fragmentary central longitudinal vertical section through the elements forming the final separating and washing space;

Fig. 4 is a likewise enlarged vertical transverse section through the trough of Fig. 2, the water ticular type, it is not my desire to thereby unnecessarily restrict the scope of the claims or the utility of the improved features.

, 4 indicated locations. This flat liquid jet which issues from the elongated straight slot 20 should having lower pole-faces disposed in close proximity to and above the lower movable loosely sagging stretch In of the belt 6; a feed chute or tray II for feeding a granular mixture of magnetic and non-magnetic material to the lower face of the belt stretch I0 near the lower pulley I; a

tailings hopper l2 forming a liquid basin adjoining the feed tray H and having arelatively low v liquid-level l3 therein; a middlings hopper H forming another liquid basin adjoining the tailings hopper l2 and having a higher liquid level therein; a magnetic material or concentrates discharge device it for delivering the final con-- centrates from the machine; a fixed plate or trough l1 interposed between the hopper l4 and the device l6 and coasting with the belt stretch l 0 to provide a final separating and washing space 18 inclined upwardly away from the liquid level IS; a pipe or conduit I9 spanning the trough l1 and having an elongated slot 20 and a similarly elongated deflector 2i for directing a fiat jet 'of liquid downwardly along the washing space l8; and means including pipes 22 and a valve 23 for admitting liquid preferably under substantiaily equal pressure to the opposite endsof the conduit l9.

Rotation is preferably imparted to the upper belt suspension pulley 8 so as to constantly advance the lower belt stretch ill in the direction indicated by the arrows, and the pulley 8 may also be provided with suitable belt'tension adjusting mechanism 24 for causing the conveyor stretch 'III to properly coact with the magnets 9. The magnets 9 are of somewhat less width than the belt 6, and are operable to create a relatively strong magnetic field along the mid-portion of the bottom surface of the lower belt stretch ID,

in order to cause the magnetic material to adhere to this belt surface and to be thus transported through the hoppers l2, H and through the final separating space l8. The concentrates discharge device is located at the upper terminus of the magnetic field produced by the magnets, and the stationary trough ,1! whichprovides the final separating and washing space I8 is formed and located-so asto cause the entire mid-portion of the spaceto be constantly subjected to the strong magnetic field, while the oppo thereof indicated by the dot-and-dash lines' in Fig. 2, are relatively free from magnetic influence.

The plate or trough ll may be provided with opposite side walls 26, and the lower ends or the plate and walls extend downwardly beneath the middlings basin water level IS, in order to prevent the loss of magnetic material to the hopper H, at the same time allowing the non-magmitted under considerable pressure equally to both ends of this conduit l9 in order to produce a sheetlike jet having'greatest intensity or volume and velocity along the central longitudinal region of the space l8 as indicated diagrammatically by the force vectors 2'! in PBS. 2 and 4, the dot-and-dash lines and arrows representing jet intensity at the site side zones 25 also be directed downwardly in contact with the material conveyed on the upwardly traveling belt stretch [0 along the final separating and washing space i8, and this action is produced by the elongated deflector 2! shown in Fig. 3. The valve 23 is provided for the purpose of controlling the magnitude or intensity .of the Jet, and maybe disposed within the common liquid supply piping system 22 whichsubsequently branches out and connects with thejopposite ends of the slotted conduit I9 as illustrated in Figs. 2 and 4.

During normal operation of the improved magnetic separator, the belt 6 is being advanced by the pulleys 1 8 so as to cause the loosely sagging plied to the lower surface of the loosely sagging 1 belt stretch l0 by the feed tray H while the hoppers l2, M are filled with liquid to the levels l3, l5 respectively. Liquid under pressure should be admitted through the pipes 22 to the opposite ends of the conduit l9 and the liquid thus admitted will cause a sheet-like spray jet to be delivered from the slot 20 of the conduit is and this jet will be directed down along the space IS in contact with the surface of the material on the belt stretch ill, by the deflector 2 l. The material entering the machine will be promptly separated by the magnetic force into gangue or tailings and more or less magnetic material, and the tailings will settle into the hopper l2 while the magnetic material including concentrates and middlings will adhere to the under surface of the belt stretch l0 and will be carried into the liquid basin within the hopper it. While passing through 'the basins inthe hoppers l2, M, the layer of ing action afforded by the liquid within these hoppers,- and when the layer of material reaches the lower end of the trough I! it will be in relatively clean condition. As the adhering and advancing layer of material is carried upwardly into the final separating space l8, it is subjected to the sweeping action of the flat sheet spray flowing at relatively high velocity down through the final separating space I8, and the sheet spray will promptly and eifectively remove the retained middlings and gangue from the layer of concen-.

trates, and will rapidly wash and, because of its greater central power or intensity, drive the renetic material .to be deposited within the'hopper Q moved middlings and gangue into the non-magnetic side zones 25 located on opposite sides of the strong magnetic field, which are relatively free from magnetic influence. The removed material and liquid will then flow quickly down the non-magnetic zones 25 into the middlings hopper [4 where the solids will settle for subsequent treatment. In this manner the concentrates are quickly and effectively purified and remain so and they will subsequently be released from the magnetic field at the upper end of the magnets 9 and will then be free to fall onto the deflector device I6 into a hopper.

When the liquidunder pressure is admitted through the pipes 22 to the opposite ends of the conduit 19, the entering columns of liquid collide near the center of the slot 20 and thus produce.

a sheet jet zhaving greatest intensity or volume and maximum velocity at the mid-portion of the slot 20 as illustratedby the vectors in the drawing, and this jet being directed downwardly along aeaaera in contact with but not directly against the layer of material carried by the belt'stretch it, will roll or sweep the middlings from the central portions of the layer and will carry these middlings toward the side non-magnetic zones 25 from which they are quickly discharged intothe hopper It without being recaptured by the magnetic field. In order to produce a proper fiat sheet jet 2? which is capable of thus quickly removing the objectionable particles from the layer, the pressure of the entering liquid at the opposite ends of the conduit 69 should be as nearly equal as possible, and the deflector 2! should be so formed and disposed that it will direct the flat sheet spray at a slight angle against the upwardly advancing bed of granular material. The flat jet will not gouge into the layer of material with sumcient force to disturb the stratiilcation.

of the material on the belt wherein the smaller particles, generally concentrates, are close to the under surface of the belt stretch it, and the coarsest particles, generally middllngs, are on the lower surface oi the sheet of material on the belt and are thus exposed to the washing and removing action of the sheet jet. Fig. 5 is an enlarged view of a portion of the belt stretch it at the region of the sheet-like spray, and indicating the approximate relationship which most of the middlings particles will generally assume in respect to the concentrate particles on the belt. That is, the small black dots represent the concentrate particles which are generally finest and closest to the belt, and the somewhat larger circles shown with partially blackened areas, are intended to represent the relatively larger middlings particles, i. e., particles containing both magnetic and non-magnetic material. Since these middlings particles are generally somewhat larger and do not contain as high a percentage of magnetic material, they are not generally attracted so strongly to the belt as the finer magnetic particles and are thus carried along in a position well adapted to be swept off by the sheet-like spray when applied in the direction of the arrow, as indicated in Fig. 5. The intensity of the jet may be readily varied by manipulating the control valve 23.

From the foregoing detailed description it will be apparent that my present invention provides an improved magnetic separator which is extremely simple and compact in construction, highly efiicient in operation, and which is less expensive to build and to operate than the prior separators of this general type. The improved machine also produces a cleaner concentrate since the gangue and middlings are more effectively removed, and the flat sheet jet will also remove slimes and other foreign matter and actually consumes less water than was required with the multiple forceful spray jets previously used. By virtue of the fact that the direction of the flat sheet jet is in opposition to the direction of travel of the belt and is substantially parallel to this belt, the layer of ore deposited upon the belt stretch 50 will be restrained downwardly and held within the final washing zone for a longer period of time, thus also insuring more eficient final washing of the concentrates. The present improvement has proven highly satisfactory and efficient in actual commercial use, and has made it possible to eliminate objectionable features of prior magnetic separators of the belt and spray jet type, with simpler and more efiicient automatically functioning equipment.

It should be understood that it is not desired liquid basin, a conveyor having a surface movable upwardly at an oblique angle away from .the

liquid in said basin, trough-like means extending along said conveyor surface to provide an inclined washing space extending upwardly away from said basin, magnetic means for creating a strong magnetic field extending along and through said space, said trough-lik means proiecting laterally beyond said field to provide side zones relatively free from magnetic influence. and means for directing a sheet-like Jet 01 liquid downwardly through said space with greatest volume and velocity near the mid-portion of the space whereby non-magnetic material is washed toward said side zones.

2. In a magnetic separator, means forming a liquid basin, a conveyor belt having a lower flat surface movable upwardly at an oblique angle away from the liquid in said basin, trough-like means extending along and beneath sai-d belt surface to provide an inclined washing space extending upwardly away from said basin, magnetic means disposed above said surface for creating a strong magnetic field extending along and through said space, said trough-like means proiecting laterally beyond the opposite sides of said field to provide side zones relatively free from magnetic influence, and means for directing a sheet-like jet of liquid downwardly through said space with greatest volume and velocity near the mid-portion of the space whereby non-magnetic material is washed toward said side zones.

3. In a magnetic separator, means forming a liquid basin, a conveyor having a surface movable upwardly at an oblique angle from within the liquid in said basin, a series of magnets for creating a magnetic field extending along said conveyor to cause magnetic material toadhere to said surface, a trough extending along and in spaced relation to said surface to provide an inclined washing space extending upwardly away from said basin and to also provide side zones relatively free from magnetic influence, and means for directing a flat and wide jet of liquid downwardly through said space so that said jet has greatest volume and Velocity near the midportlon of the space whereby non-magnetic material is washed into said basin through said side zones.

4. In a magnetic separator, means forming a liquid basin, a conveyor belt having a lower flat surface movable upwardly at an oblique angle irom within the liquid in said basin, a series of magnets above said belt for creating a magnetic field extending along the conveyor to cause magnetic material to adhere to said surface, a trough extending along and beneath and in spaced relation to said surfac to provide an inclined washing space extending upwardly away from said basin and to also provide opposite side zones relatively free from magnetic influence, and means for directing a fiat and wide jet of liquid downwardly through said space so that said jet'has greatest volume and velocity near the mid-portion of the space whereby non-magnetic material is washed into said basin through said side zones.

5. In a magnetic separator, a hopper forming a settling basin, a belt conveyor having a lower surface movable upwardly away from said basin. magnets for creating a magnetic field sufficiently strong to cause magnetic material to adhere to said belt surface. a trough extending along and beneath said surface to provide an inclined washfor supporting and moving said belt stretch totravel from a position in proximity to the liquid along an upwardly inclined path to a concentrates discharge position, magnetic means extending along above said belt stretch for causing magnetic particles to adhere to the underside of the belt, trough-like means extending along said inclined path in spaced relation to the belt at regions above the liquid level to form a washing space within the field of said magnetic means, said trough-like means also extending to zones alongside the belt which are beyond any strong infiuence of said field, and means for directing a sheet-like jet of washing liquid downwardly along the underside of the belt in said space, said jet having substantially greater velocity and volume at the mid-portion of the belt than at regions nearer said side zones, whereby particles embodying non-magnetic material are washed from the belt to the side zones and thence downwardly along the trough-like means.

7. In a magnetic separator, a belt stretch, hopper means for containing a body of liquid, means for supporting and moving said belt stretch to travel from a position in contact with the liquid along an upwardly inclined path to a concentrates discharge position, magnetic means extending along above said belt stretch for causing magnetic particles to adhere to the undersid of the belt, trough-like means extending along said inclined path in spaced relation to the belt atregions above the liquid level to form a washin space within the field of said magnetic means, said trough-like means also extending to zones alongside the belt which are beyond any strong influence of said field, a conduit having a slot extending transversely of and opening into said space, and means for connecting sources of wash liquid under pressure to both ends of said conduit, whereby a sheet-like Jet of wash liquid is projected from said slot downwardly along the underside of the Ht in said space, the two sources of the wash liquid causing said Jet to have greater velocity and volume at its mid-portion than at regions nearer said side zones to thereby cause particles embodying non-magnetic material to be swept from the belt to zones where the field is insufficient to cause substantial amounts thereof to be recaptured on the belt.

8. In a magnetic separator, a hopper forming a settling basin, a belt conveyor having a lower surface movable upwardly away from said basin, magnets for creating a magnetic field sumciently strong to cause magnetic material to adhere to said belt. surface, a trough extending along and beneath said surface to provide an inclined washing space extending upwardly away from said basin and having opposite side zones which are relatively free from magnetic influence, a conduit having an elongated slotopening into an upper portion of said space and formed to direct a flat jet of washing liquid downwardly along said space. and means for delivering liquid under pressure into the opposite ends of said conduit to cause said jet to have greatest intensity near its midportion and remote from said zones.

9. In a magnetic separator, means forming a settling basin, a conveyor having a lower surface movable upwardly away from said basin. magnets for creating a magnetic field adjacent to said surface, a trough forming a washing space extending along said surface and having its midportion within said field and opposite side zones relatively free from magnetic influence, a conduit formed to direct a fiat jet of washing liquid downwardly along said space, and means for deliverins liquid under pressure into said conduit to cause said jet to have greatest intensity near the midportion of said space and remote fromsaid zones.

10. In a magnetic separator, means forming a settling basin, a conveyor having a lower surface movable upwardly away from said basin, magnets for creating a magnetic field adjacent to said surface, a trough forming a washing space extending along said surface and having its mid-portion within said field, a conduit formed to direct a fiat jet of washing liquid downwardly along said space toward said basin, and means for delivering liquid under pressure into the opposite ends of said conduit to cause said jet to have greatestv intensity near the mid-portion of said space.

11. In a magnetic separator, abelt conveyor having an inclined upwardly movable stretch, magnetic means arranged along the upper surface of said stretch for causing magnetic particles to adhere to the under surface thereof, troughlike means extending along beneath said stretch in spaced relation thereto, and means for projecting a sheet-like spray of washing liquid in a direction downwardly along a plane generally parallel to said stretch, between said stretch and trough-like means, said spray projecting means being so constructed and arranged that the spray along regions nearer an edge of the belt has less force than along regions more widely spaced from the edge of the belt, whereby particles dislodged from the belt by the spray tend to be swept to the side of the belt.

12. In a magnetic separator, a belt conveyor having an inclined upwardly movable stretch, magnetic means arranged along the upper surface of said stretch for causing magnetic particles to adhere to the under surface thereof, means for applying a liquid mixture of particles to be sepa-' rated, to the under side of a lower of said stretch, trough-like means extending up along beneath said stretch in spaced relation thereto, and means for projecting a sheet-like spray of washing liquid having greatest intensity near its mid-portion, in a direction downwardly along a plane generally parallel to said stretch, between said stretch and trough-like means, at a region above the liquid level.

13. In a magnetic separator, conveyor means having an upwardly curved upwardly movable surface portion, magnetic means arranged along the upper side of said surface portion for causing magnetic particles to adhere to the underside thereof, trough-like means extending along beneath said surface portion in spaced relation thereto, and means for projecting a sheet-like spray of washing liquid in a direction downwardly along a plane generallytangent to said surface portion, between said surface portion and said R l s -like means, said spray projecting means bein so constructed and arranged that the spray along regions nearer an edge of the surface portion has less force than along regions morewidely spaced from such edge, whereby particles dislodged from the surface by the spray tend to be swept toward such edge.

14. In a magnetic separator, conveyor means having an upwardly curved upwardly movable surface portion, magnetic means arranged along the upper side of said surface portion for causing magnetic particles to adhere to the underside thereof, means for applying a liquid mixture of particles to be separated, to the underside of a lower portion of said conveyor means, trough-like means extending up along beneath said surface portion in spaced relation thereto, and means for projecting a sheet-like spray of washing liquid 3 the liquid level.

10 having greatest intensity near its mid-portion, in a direction downwardly along a plane generally tangent to said surface portion, between said portion and trough-like means, at a region above ROBERT E. CROCKE'I'I.

REFERENCES CIT-ED The following references are of record in the 1 file of this patent:

UNITED STATES PATENTS

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