US 2954122 A
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Sept. 27, 1960 w. A. COLBURN METHOD AND APPARATUS FOR SEPARATING MATERIALS Filed June 17, 1957 2 Sheets-Sheet 1 FEED CONCENTRATE I3 15 ZERH CLEANER $-I4 NON MAGNETIC MATERIALS FXER bJ|AGNET |ZER H s PARATOR HDEMAGNETI William A. Colburn BY ATTORNEYS Sept. 27, 1960 A, OLB N 2,954,122
METHOD AND APPARATUS FOR SEPARATING MATERIALS Filed June 17, 1957 I v 2 Sheets-$heet 2 I II OI William A. Colburn ATTORNEYS METHOD AND APPARATUS FOR SEPARATING MATERIALS William A. Colhurn, Denver, Colo., assignor to Petroleum Research Corporation, Denver, Colo., a corporation of Colorado Filed June 17, 1957, Ser. No. 665,903
6 Claims. (Cl. 209-8) 'netic material. Magnetic separators are employed widely in the mining industry, some being adapted for use in dry, pulverized ore and others in wet, ground ore or slurry. In general, these separators will separate moremagnetic material from less-magnetic material; however, when the more magnetic material is only weakly magnetic or when the material is very finely divided, the force exerted by the magnetic field of the separator often is not t ti States Patent r sufficient to remove the more magnetic material effectively. This dimculty arises because the magnetic forces are not sufficiently strong to force the more magnetic material through the mass of material so that the particles of 'rnagnetic material can reach the magnetic pole or collector;
is further increased because the more magnetic material must be drawn through the mass of material in directions transverse to the direction of flow or movement of the mass of material. The conventional magnetic separators and, in most types of commercialseparators, this difliculty I,
are highly eflective for separating ferro-magnetic material from non-magnetic material; however, they are not entirely satisfactory for separating and collecting weak magnetic materials. By way of example,- the present com mercial separators are relatively ineflicient when employed to separate weakly magnetic tungsten ores such as W01- frlann'te from the rock in which they occur. Accordingly,
it is an object of the present invention to provide an improved method for separating weakly magnetic materials from non-magnetic materials.
It is another object of this invention to provide an int-- provide method for treating a mass of finely-divided materials to separate the more-magnetic material from the fless-magnetic material in the mass.
1 It is a further object of this invention to provide an improved apparatus for separating more-magnetic material from less-magnetic material.
Briefly, in carrying out the process of this invention "in one form thereof, a mass of material to be treated, for example a relatively-thick slurry formed from finelydivided tungsten ore, is thoroughly mixed with a-multi- -pliicity of relatively large bodies of highly-magnetizable material such as balls or shotlike bodies of alnico. The mixture'is then passed through amagnet-ic field to magnetize the alnico bodies and is then passed to a conventional magnetic separator to remove the alnico bodies from the moving'mass of the ore. 'When the mass of material is treated in this way, the magnetic bodies pick up finely-divided weakly-magnetic material within the mass andcarry it with them through the magnetic separation :process so that the magnetic bodies are'removed with finely-divided weakly-magnetic matenialadhering ,to them.
2,954,122 Patented Sept. 1960 The weakly-magnetic material which is to be recovered is then cleaned fromthe magnetic bodies, preferably by tie-magnetizing the bodies and washing them over a screen so that the finely-divided ore and the bodies are thereby separated. The bodies are then returned to move again through the process. This method may similarly be applied to dry, pulverized ore and, in some applications, the separation may be accomplished by a mechanical ap-v paratus instead of by a magnetic separator. In another form, magnetic bodies secured to a moving belt may be employed instead of the free bodies. The apparatus employed in practicing the invention in one embodiment thereof comprises a mixing hopper and an agitator for thoroughly distributing the magnetizable bodies through? out the mass of finely-divided ore. A conveyer then care ries the mixture through a magnetizing field for magnetizing the highly-magnetizable bodies. The mixture is then discharged and delivered to a magnetic separator which separates the magnetizable bodies from the mixture and discharges them through a de-magnetizing field. A wash.- ing and screening apparatus is then arranged to receive the de-magnetized bodies and to clean them and remove the adhering pulverized material which is collected while the magnetizable bodies are returned to the beginning of the circuit.
The features of novelty which characterize this invention will be pointed outwith particularity in the appended claims' The invention itself, however, both as to the method for treating finely-divided material and as t9 the organization and arrangement of the apparatus embodying the invention, together with further objects and advantages thereof, will be better understood upon refer.- .ence to the following description taken in connection the accompanying drawings in which:
Fig. 1 is a block diagram or flow sheet illustrating the process of the invention; a
Fig. 2 is a diagrammatic illustration of a wet process apparatus for separating materials in accordance with the inv ntion;
' Fig. 3 is a diagrammatic illustration similar to Fig. 2 showing a dry-type apparatus for separating materials in accordance with the invention;
Fig. 4 is a plan view of the apparatus diagrammatically sh w i ig- Fig.5 is a diagrammatic illustration of a dry process apparatus including another embodiment of the invention Pig. 6 is 'a diagrammatic illustration of a further embodirnent of the invention;
Fig. 7 is a diagrammatic illustration of a still further embodiment .of the invention; and
Figs. 8 and 9 illustrate modified forms of magnetic belts for use in apparatus of the type shown in Figs. 6 and 7 Referring-now to the drawing, the several steps in the process of the present invention are indicated in thc block diagram in Fig. 1. In carrying out the process, a finely-divided ore or other material containing moremagnetic and less-magnetic materials, from which it is desired to remove the more magnetic material as a concentrate, is supplied to a mixing apparatus indicated at '10. The feed may be either wet or dry depending on the materials to be handled and the apparatus available.
netizab le material; this material, for example, maybe ,a
quantity of shotor spheres of highly-magnetizable mate- .rial such as alnico. The magnetizable bodies and thc .feed are thoroughly mixed in the mixer 10 and are then supplied to a magnetizer 1 1 which magnetizes the larger "bodies and also other magnetizable particles in the mix. The complete mixture is .then supplied to a n'agrieticgr niechanieal separtor .12 which removes the large bodies togetherwith any small particles of magnetic material 3 adhering thereto and supplies them to a demagnetizer 13 while the non-magnetic material is discharged through an outlet indicated at 14. From the de-magnetizer 13 the bodies and adhering ground material are supplied to a cleaner 15 which removes the adhering material and discharges it through a concentrate outlet 16 while returning the bodies of magnetizable material through a return path indicated at E7. The effectiveness of this process depends upon the action of the magnetizable bodies when they are magnetized within the mass of material. The thorough mixing of the bodies in the mass of material assures the presence of magnetic poles throughout the material when the mixture passes through the magnetizer it. Thus the magnetic poles are provided colse to the magnetic particles within the material and the particles are not required to pass through substantial portions of the body of ground material in order to reach a magnetic pole. The small particles cling to the surfaces of the magnetic bodies and are carried to the magnetic separator where the bodies are removed from the nonmagnetic pulverized material and carry with them the magnetic material which is held on the surfaces of the bodies by magnetic force. The magnetized bodies have been represented in the drawing as having irregular surface outlines due to the particles atracted thereto. The separator 12 is preferably a magnetic separator which readily removes the larger bodies of magnetized material; however, other forms of separators may be employed which will remove the larger bodies from the pulverized mass; for example, a trommel may be employed to screen out the finer non-magnetic material and to deliver the magnetized bodies and adhering material to the demagnetizer 13. After the magnetic bodies have been demagnetized, they are passed to the cleaner which may be of any suitable type; for example, a screen and washing spray may be employed when the process is a wet process and a blower and dust collector may be employed in the dry process. The return circuit 17 for the magnetizable bodies may be of any suitable construction; for example, it may be a continuous belt or a chain and bucket device. Regardless of the apparatus employed, the essential feature of the process of this invention is the and then discharged through a connection 20a to a rotary pump 26 which forces the mixture to flow through a conduit 27 and thence to a tank or trough 28 of a belt-type magnetic separator fit). The pump 26 serves to propel the mixture and also to mix the magnetizable bodies or shot more thoroughly and more uniformly throughout the finely-divided ore mass. In order to magnetize the shot 24 as the mixture passes through the conduit 27, a directcurrent magnetizing coil 32 is arranged about the conduit and is energized by a suitable directcurrent source indicated diagrammatically as a battery 33. The coil 32 produces a magnetic field extending along the axis of the conduit 27 and the magnetic bodiespassing therethrough are thus magnetized. The magnetized bodies tend to collect in strings, and, furthermore, magnetic material contained in the finely-divided material mixture is also magnetized and collects on the shot; furthermore, as the shot moves together through the mixture, it passes in close proximity to the slightly magnetic particles in the mixture and they readily adhere to the shot and travel along with it. In this manner, strong magnetic poles are provided throughout the mixture so that none of the material has to travel a great distance through the moving mixture in order to reach a magnetic pole and even weakly-magnetic material is collected from the mixture of material flowing through the conduit. The material then flows through the magnetic separator 30 below a belt 34 mounted for movement about two drums or wheels 35 and 36 and driven in the direction of movement of the material toward an outlet weir 37. As the material passes the central area of the belt, between the two drums, it comes within the field of a series of magnets indicated generally at 38, and the relatively large bodies of highly-magnetized material are drawn against the belt by the, magnets and are carried along until the belt reaches the end of the magnets 38 whereupon the magnetic bodies are released and fall into a funnel or catching bin,
. the non-magnetic materials and the liquid continuing distribution of magnetic poles throughout the mass of material to be treated so that none of the material is required to travel any substantial distance in order to reach a magnetic pole and to be separated from the other material. This method has been found eifective for removing relatively weak magnetic materials from a mass of nonmagnetic material and, forv example, has been found suitable for removing tungsten ore such as wolframite from the rock in which it occurs. In some applications, the magnetic field of the separator will be sufiicient for magnetizing the bodies and the separate magnetizing coil is unnecessary; also, for separating some materials it may be found unnecessary to employ the demagnetizing coil before passing the magnetic bodies to the cleaning apparatus.
Many different types of apparatus for performing the functions of the components of the system indicated in Fig. 1 may be employed for the carrying out of the process of this invention. By way of example, in Fig. 2 there is illustrated a system employing a wet process and arranged to separate more magnetic material from less magnetic material contained in a pulp or slurry of ore. A system of this type may be employed, for example, to separate wolframite or tungsten ore from the tailings flowing from a molybdenum ore mill. In the system of Fig. 2, a mixing chamber or hopper 20 is supplied with a pulp or slurry through an inlet duct 21 and the pulp within the tank 20 is agitated by an impeller 22 driven by suitable mechanism (not shown) through a shaft 23. Highly magnetizable material, preferably in the form of small spheres or shot 24 and which may be 'alnico, is supplied to the tank 20 through a conduit or supply chute 25 and the shot and slurry in the tank 20 are thoroughly mixed through the tank and out over the weir 37. As the bodies 24 fall downwardly from the funnel 40, they pass through a duct 41 and are de-magnetized by operation of an alternating magnetic field produced by a coil 42 connected to a source of alternating current 43. The de-magnetized bodies fall onto a suitable cleaning apparatus which has ben shown as a screen 44 and are cleaned by suitable mechanism which may be a spray head 45 arranged to spray the de-magnetized bodies with water and wash the finely-divided material adhering thereto through the screen and into a collecting funnel 47 from which it may be removed through a duct 48. The magnetized bodies 24 fall from the screen into a collecting funnel 50 and thence through a duct 51 to a return mechanism indicated diagrammatically as a bucket chain 52 so that the bodies 24 are returned through the supply duct 25 to the tank 20.
The operation of the system shown in Fig. 2 is continuous and makes it possible to remove relatively-weak magnetic materials such as wolframite from non-magnetic material such as the rock in which tungsten ores occur. The process of this invention, by bringing strong magnetic polesinto close relationship with the finely-divided material throughout the mass of material, makes it possible to remove small particles of magnetic material and weakly-magnetic material from a mass of moving mate rial although such particles would not be effectively removed by the action of conventional magnetic separators.
The apparatus illustrated in Figs. 3 and 4 is similar to that illustrated in Fig. 2 but is of the type which may be employed for operation on dry materials or powder. In the apparatus of Figs. 3 and 4, the process of the invention is carried out by supplying dry pulverized material to be treated and relatively-large highly-magnetizable bodies to a hopper 5 4 which feeds a mixer 55 from which tween 5 7 and 58. The supply of mixed material, indicated at 59, moves along with the belt through a. nonmagnetic cylinder 61 about which is arranged a magnetizing coil 62 supplied with direct current from a suitable source 62a. Thus, as the material on the belt 56 passes through the cylinder-61, the highly-magnetizable bodies are magnetized to provide strong magnetic poles throughout the mixture, thereby attracting particles of weaklyinagnetic material to the bodies Within the mass 59. The material 59 then passes through a magnetic separator indicated generally at 63 and comprising suitable magneticpole pieces 64 and 65 arrangedon the upper and lower sides of the belt 56 to provide a magnetic field extending through the material 59. The separator 6'3 may also be provided with a stirrer or agitator (not shown) to release non-magnetic material held mechanically to the magnetic material moving to the belt. The magnetized bodies are drawnthrough the mass of material 59 toward the pole 64 and are caught on the bottom side of the lower pass of a cross belt 66 by which they are moved transversely of the path of the belt 56 and carried through a tie-magnetizing coil 67 supplied with alternating current from a suitable source 68; thus, the magnetized bodies in the material are demaguetized and then fall from the belt 66 at the upper end as viewed in Fig. 4 and may be collected-in a suitable hopper 70. The particles adhering to the bodies of magnetic material may then be removed by a suitable cleaner (not shown) and the magnetizable bodies-returned'to the hopper 54. The non magnetic materialiscarried to the end of the belt 56 and hails from the belt asit passes over the drum 58 and may then be transported in any suitable-manner to the Waste or tailings dump. 7
As illustrated in Fig. 5, it may be desirable in some applications to employ a mechanical separator other than a magnetic separ'tor for removing the bodies of magnetizable material from the-mass of pulverized material. The apparatus of Fig. 5 is essentially similar to that of Figs. 3 and 4 and corresponding parts have been designated by the same numerals with the addition of the suflix a. Instead of passing to the magnetic separator 63 of Figs. 3 and 4, the belt 56a delivers the mixture of pulverized material and magnetized bodies to a trome mel or rotating screen 71 which screens the non-magnetic material from the magnetized bodies and the more-magnetic material adhering thereto. The magnetized bodies and the material which they carry then pass through a conduit 72 into a hopper 73. A de-rnagnetizing coil 74 is provided about the conduit 72 and the magnetized bodies are thereby de-magnetized before being supplied to the hopper where the adhering material is cleaned therefrom before the bodies are returned to the beginning of the circuit. The concentrate comprising the moremagnetic materials secured by cleaning the magnetic bodies is then collected and delivered for use or shipment.
Instead of employing free magnetizable bodies such as the shot or balls used in the apparatus illustrated in Figs. 2 through 5, the magnetizable members may be secured to a suitable anchoring means such as a belt or chain so that they can be moved along with or drawn through the finely-divided material to be treated. By way of example, there is illustrated in Fig. 6 a portion of a dry-type apparatus similar to that of Figs. 3 and 4 and which is provided With a belt carrier for the magnetizable bodies. The parts of the apparatus corresponding to parts of the apparatus of Figs. 3 and 4 have been designated by the same numerals with the suffix letter b. In this modification, a continuous, flexible belt 75 is mounted to move over drums 76 and 77 and has secured to it a multiplicity of magnetic spikes or bars 78 extending longitudinally of thebelt and parallel to its surface and secured to the belt on suitable posts 79. The magnetizable elements 78 which may be made of alnico or other highlymagnetizable material are arranged in staggered relationship so that, as the belt which is mounted parallel to the belt 56b passes adjacent the belt 56b, the magnetizable members will lie at'various depths within the mass of material to be treated, indicated at 59b. Both belts pass through a field produced by a coil 62b and the elements 78 are thereby magnetized and collect particles. of more-magnetic material from the mass of material 59b through which the magnetizable elements are passing. The belt75 extends beyond the drum 58b for the belt 56b and then passes through a demagnetizing field produced by a coil 67b surrounding the belt and energized from a suitable source of alternating current 68b. Pa;rticles falling from the magnetizable elements 78 after they have been ale-magnetized drop to a hopper 70b and any particles still adhering to the elements 78 are blown'therefrom by an air blast indicated generally at 80 as the belt turns upwardlyover the drum 77.
' In Fig. 7,there is shown an apparatus wherein a belt similar to the belt 75 of Fig. 6 is employed as the main transporting belt of the system. 'In this system, a belt is arrangedto move over drums 86 and 87 a d material to be treated is supplied to the belt from a suitable hopper 88 and mixer 89 supplied with a mixture of the finely-divided material-to be treated. The belt is constructed in essentially the same manner as the belt 75 of Fig. 6 so that the material supplied to the belt is distributed about a plurality of short magnetic elements or bars 90 extendinglongitudinally of the belt' in stag gere'd positions overthe surface ofthe belt and spaced therefrom. Material then passes through a magnetizing coil 91 which magnetizes the bars 90 and causes them to pick up finely-divided rnore-magnetic material from the material on the belt, then as the material falls from the belt when it turns over the drum 87, the magnetic bars 90 carry thecollected material downonto the underside of the belt" which then passes through a de magnetizing field produced by a coil 93 energized by a suitable source of alternating current 94. When the bars 90 are thus de-magnetized, the particles adhering thereto fall and any which do not fall ime may be cleaned from the bars by an air blast indicated at 95. The finely-divided material thus removed may be collected in any suitable manner such as by a vacuum machine having a collecting filter bag as indicated at 97.
Other for-ms of belts carrying magnetic elements and suitable for use in applications such as those of Figs. 6 and 7 are shown in Figs. 8 and 9. The belt shown in Fig. 8 comprises a series of longitudinal non-magnetic wires 98 woven together with a plurality of short magnetic wires 99, thereby forming a grid having magnetic pole members extending across the longitudinal wires. When a belt of this type is magnetized by a field having its lines of force extending parallel to the Wires 98, the Wires 99 are magnetized oppositely on their front and trailing edges. The arrangement shown in Fig. 9 is similar to that of Fig. 8 except that the magnetizable wires, indicated at 100, are provided with additional elements or barbs 101 in a manner similar to that employed in making barbed wire, thereby distributing the magnetic-poles more completely throughout the mass of material to be treated.
While the invention has been illustrated and described in connection with particular applications, other applications and arrangements of apparatus will occur to those skilled in the art. Therefore, it is not desired that the invention be limited to the specific embodiments and methods illustrated and described and it is intended by the appended claims to cover all modifications which fall Within the spirit and scope of the invention.
1. In the materials separating art, the method of separating particles of more magnetic material from a mass comprising particles of more magnetic material and particles of less magnetic material which comprises mixing in the mass relatively large bodies of highly magnetizable material of high retentivity, passing the bodies through a magnetic field to magnetize them,'said bodies retaining their magnetism after passing from the magnetic field, separating the bodies and particles magnetically held thereon from the remainder of the mass, and cleaning the bodies to remove and collect the particles of material therefrom.
2. In the materials separating art, the method of separating particles of more magnetic material from a mass comprising particles of more magnetic material and particles of less magnetic material, which comprises mixing in the mass relatively large tree bodies of highly magnetizable material, moving the mass of material with the magnetizable bodies therein into a transversely acting magnetic field to magnetize the bodies, passing the mass through a magnetic separator to separate the bodies with particles of more magnetic material thereon from the remainder of the mass, demagnetizing the bodies, cleaning the bodies to remove the particles of material therefrom, and collecting the removed material.
3. The method of separating more magnetic materials from less magnetic materials which comprises mixing a mass of finely-divided material to be treated and a quantity' of substantially larger free bodies of readily magnetizable material to distribute the bodies throughout the mass of finely-divided material, subjecting the mixed mass to a magnetic feld to magnetize the bodies, separating the bodies and finely-divided material clinging thereto from the remainder of the mass, demagnetizing the bodies, and cleaning the bodies to remove the finely divided material therefrom.
4. In the magnetic material separating art wherein a magnetic separator is employed to remove more magnetic particles from a mass of less magnetic particles, the method of facilitating the removal of the more magnetic particles which comprises mixing free bodies of readily magnetizable' material in the mass of particles tobe treated and magnetizing the bodies prior to supplying the mass of material to the magnetic separator whereby the bodies with more magnetic particles clinging thereto are removed from the mass by the separator, and thereafter cleaning the bodies to removethe particles of material therefrom;
5. The method for facilitating the removal of more magnetic material from less magnetic materials as recited in claim 4 including the further step of demagnetizing the separated bodies prior to cleaning them to remove particles therefrom. 6. In the materials separating art, .the method of separating particles of more magnetic material from a mass comprising particles of more magnetic material and particles of less magnetic material which comprises distributing in the mass at a plurality of 'difierent depths therein relatively large bodies of highly magnetizable material of high retentivity, subjecting the bodies to a magnetic field to magnetize them while in said mass, said bodies retaining their magnetism after removal of the magnetic field, separating the bodies and particles magnetically held therein from the remainder of the mass, and cleaning the bodies to remove and collect particles of material therefrom.
References Cited in the file of this patent UNITED STATES PATENTS Great Britain Dec. 7,