US3058589A - Electrostatic separator - Google Patents

Description

Oct. 16, 1962 J. H. CARPENTER ELECTROSTATIC SEPARATOR 2 Sheets-Sheet 1 Filed March 1, 1961 INVENTOR.

JAMES H. CARPENTER J m Back, {Melina NJG):

FIGI

ATTORNEYS.

Oct. 16, 1962 J. H. CARPENTER 3,058,589

ELECTROSTATIC SEPARATOR Filed March 1, 1961 2 Sheets-Sheet 2 INVENTOR. JAMES H.CARPENTER BY 6 MW, BM, iwwdlwsmh ATTORNEYS 3,058,589 Patented Oct. 16, 1962 3,058,589 ELEQTROSTATiC SEI ARATOR James Hall Carpenter, Jacksonville, Fla, assignor to Carpco Research & Engineering, Inc., Jacksonville, Fla, a corporation of Florida Filed Mar. 1, 1961, Ser. No. 92,509 7 Claims. (Cl. 209129) This invention relates to an improved apparatus for separating materials. More particularly, the invention relates to electrostatically separating materials such as mineral ores into discrete groups of varying characteristics.

Apparatus for the electrostatic separation of minerals receives wide use in industry. One type of such apparatus is the Sutton Separator, disclosed, for example, in Handbook of Mineral Dressing by Taggart. In conventional electrostatic separation of minerals, ore may be fed from a hopper onto a rotating drum which is charged positively as by a stationary brush connected to ground. In close proximity to the drum is a stationary electrode, such as a comb comprising a rod having a plurality of discharge points extending toward the drum. On passing over the rotating drum, the more conductive particles lose electrons through the grounded drum, and are then attracted to the negatively-charged active electrode. The less conductive particles lose electrons to the drum more gradually, and hence are negatively charged with respect to the drum so that they adhere, or become pinned to the drum. When carried by rotatation of the drum beyond the influence of the active electrode, the pinned particles drop from the drum by gravity. Bins or collectors, divided from one another by vanes or splitters, may be disposed beneath the drum and active electrode so as to selectively collect the thrown group, or these particles attracted toward the electrode and thus falling farthest from the drum, and the pinned group, the particles of which adhere to the drum. Where a fine division of discrete groups of particles is desired, those particles known as the middlings, which fall between the pinned and thrown groups, may be collected as still another discrete quantity.

In apparatus where a plurality of units arranged in stages is desired, with each unit represented by an appa- A further object of this invention is to provide an improved multi-stage electrostatic separator in which collection of dust on electrodes is minimized or eliminated.

A still further object of this invention is to provide an improved multi-stage electrostatic mineral separator which is totally enclosed but accessible as to any portion thereof.

Briefly, and in accordance with one aspect of the invention, the electrostatic separator of this invention includes a plurality of separator units disposed in stages one above the other, each of these units comprising electrode means, generally known in the art, for separating material into discrete quantities or groups of fragments, each quantity having differing characteristics. A first feeding means, such as a hopper, delivers material to an upper one of the separator units. A second feeding means, such as a duct, selectively communicates with the first feeding means, and bypasses the upper unit to supply material to a lower separator unit. Extending from beneath the upper separator unit are a plurality of conduits to collect the separated quantities and convey them downwardly in separate streams. Each of these conduits is selectively connectible to the second feeding means, so that the fragments being carried by the con duits may be discharged into the second feeding means to be supplied to the next lower unit, or, if disconnected from the second feeding means, may be made to bypass the second feeding means, and thus the next lower unit. A third unit may be added below the first two units, and means for interchanging the separate flows may be provided between the intermediate unit and the bottom unit ratus of the type just described, the problem arises of collecting the discrete quantities separated by one unit and directing these quantities in a desired flow pattern to subsequent units. Thus, it may be desired to direct the thrown quantity of particles from one unit to another to be subjected to a second stage of separation.

Similarly, it may be desired to further treat only the pinned particles, or the middlings. In heretofore known apparatus it has been necessary to set up a complex and space wasting system of chutes, slides ducts, or the like, to provide the desired flow pattern. Once the apparatus is set up for a given pattern, as by the manufacturer, it is diflicult for the user to make alterations in the field to change readily from one flow pattern to another. It is then necessary to engage pipe fitters, sheet metal workers, or such specialists in order to make the desired alterations.

A further problem in apparatus of this type arises from the fact that dust, an unavoidable concomitant to the process, tends to collect upon the active electrodes and their mountings, causing diminished efliciency or even short circuiting.

An object of this invention is to provide an improved multi-stage electrostatic separator which is compact, yet permits any of a plurality of alternate flow paths for the various separated quantities of material to be obtained with speed and facility.

similar to that described above as provided between the upper and intermediate units. As many additional units as desired may be added.

In accordance with another aspect of the invention, the charged electrodes of each separator unit are mounted upon a single, upright conductor in ladder fashion. This conductor is enclosed by a duct. An apparatus, which may comprise two or more assemblies of the separator units, is enclosed Within a wall structure, and air is moved by suitable means from Within the enclosure through the electrode conductor duct. This results in a wind sweeping of the electrodes with consequent minimization or even elimination of dust collection on the electrodes which otherwise causes undesirable loss of efiiciency and even short circuiting.

Further objects, features, and attending advantages of the invention will become apparent by reference to the following detailed description and accompanying drawings in which:

FIGURE 1 is a schematic view in side elevation of i the apparatus of this invention comprising two side-byside assemblies;

FIGURE 2 is a fragmentary detailed section of the duct and conduit interchange arrangement;

FIGURE 3 is a fragmentary detailed section similar to FIGURE 2, showing an alternative flow arrangement; and

FIGURES 4, 5 and 6 are schematic views, each in side elevation of a given one of the separation assemblies, and each illustrating a particular flow pattern possible with the invention apparatus.

With reference to FIGURE 1, there is shown an electrostatic separator apparatus comprising two side-by side assemblies. One assembly comprises individual separator units disposed one above the other and indicated generally at 100, 200, and '300. The other assembly comprises like separator units, also disposed one above the other and indicated generally at 100', 200", and 300'. The apparatus will be described by reference to the first assembly, in which feed means comprising ducts 101, 201, and 301 deliver material to be electrostatically separated to each of the units 100, 200, and 300, respectively. The discharge openings of feed means 101, 201, and 301 may be opened or closed by movable gate means 102, 202, 302. While it may be understood that this invention will have application in various embodiments of electrostatic separators the separator units illustrated herein each comprise a rotatable drum, indicated at 103, 203, and 303, respectively, These drums are charged and are in contact with grounded brushes 104, 204, and 304. Disposed in close juxtaposition to drums 103, 203, and 303 are electrodes 105, 205, and 305, charged oppositely relative to their drums. The structure and operation of the rotatable drum type separator shown is well known to the art and will be described herein only to the extent necessary to a complete understanding of the invention. As previously described, material to be electrostatically separated, which is delivered to one of the rotating drums by its associated feed means, passes though the electrostatic field created by the positively charged drum and the adjacent electrode. The more conductive particles are attracted to the negative electrode, while the less conductive particles adhere or become pinned to the drum. The middlings follow a path intermediate of the pinned and thrown particles. The latter are those attracted to the negative electrode. In order to separate the groups of particles thus separated, there is provided beneath each drum two splitting vanes. Thus, below unit 100 there are provided adjustable vanes 106 and 107 which divide the separated particles and direct them downwardly through conduits 108, 109, and 110. Similarly, beneath unit 200 there are provided adjustable vanes 206 and 207 which divide the separated particles into streams which are directed downwardly through conduits 208, 209, and 210. Likewise, beneath unit 300 there are provided adjustable vanes 306 and 307 which divide particles separated by unit 300 and direct them downwardly through conduits 308, 309, and 310.

In accordance with the invention, means for accomplishing a refined degree of selectivity in the material flow pattern through the separator apparatus includes conduits to by-pass any one or more of the units of an assembly. Thus, a conduit in the form of a duct 112 is selectively communicable with the first feed means, or hopper, 101. This selective communication may be accomplished by any convenient means, but is illustrated here as being accomplished by a pipe 111 which may be connected with an aperture in the hopper 101, such aperture being closable by a suitable valve should it be desirable not to bypass the first unit 100 by diversion of the material through duct 112. The lower end of duct 112 communicates with second feed means 201.

Thus separator unit 200 may receive either rough material which has bypassed unit 100, or any of the quantities of separated material leaving unit 100 via conduits 108, 109, 110. In addition, means are provided to bypass any of thesestreams of separated material past separator unit 200. Similar to duct 112 which selectively comunicates with the firstfeeding means, there is provided a duct 212 selectively.communicating with the second feeding means 201, as by valved pipe 211. Thus, material fed downwardly through second feeding means 201 may bypass unit 200 by being diverted through duct 212.

Communicable with conduits 108, 109, 110 are a plurality of conduit extensions 108a, 109a, 110a. These conduit extensions are insertable into and withdrawable from second feeding means 201, as hereinafter more fully described with reference to FIGURES 2 and 3. When the conduit extensions are connected into and through duct 201, they communicate withthe conduits 108, 109, 110. In that circumstance, the material flowing in any or all of conduits 108, 109, 110 can be made to pass through and hence bypass the discharge end of duct-201 and therefore separator unit 200. By removing the conduit extensions 108a, 109a, 110a from duct 201, and closing their openings into the duct 201, material flowing through conduits 108, 109, 110 will enter duct 201 and thus be directed to separator unit 200. As a further alternative, the gate 202 may be closed and bypass means 211, 212, in the form of a duct, may be selectively connected to second feed means 201 below the outlets of conduits 108, 109, 110 to bypass unit 200 and direct material downwardly for separation by unit 300.

In accordance with the invention, material may be fed to unit 300 by means of either third feed means 301 or any or all of conduits 208, 209, 210. In the alternative and still in accordance with the invention, any or all of these streams of material may be made to bypass unit 300 exactly as described above. Selectively communicable with conduits 208, 209, 210 are a plurality of conduit extensions 208a, 209a, 210a insertable into and through or Withdrawable from third feed means 301. By inserting conduit extensions 208a, 209a, 210a through duct 301, the separated material traveling downwardly from unit 200 may be made to pass entirely through third feed means 301, and hence will bypass separator unit 300. In the alternative, by removing conduit extensions 208a, 209a, 210a and closing their openings into duct 301, this material may be directed into third feed means 301 and thence to separator unit 300. In still another alternative, material fed downwardly through duct 212 and third feed means 301 can be bypassed around unit 300 by closing gate 302 and making use of duct 312 which is selectively communicable with its associated feed means 301.

With reference, now, to FIGURES 2 and 3, the structure of .a prefered embodiment of the means by which the flow selectively above described will be set forth in detail.

With reference to FIGURE 2, the feed means 201 is illustrated disposed to discharge downwardly upon rotatable drum 203 of unit 200. Conduits 108, 109, 110, carrying the quantities of material which have been segregated by the action of separator unit 100, intersect the duct wall of feed means 201. Provided in the upper wall of feed means 201 and communicating with conduits 108, 109, 110, respectively, are apertures or openings 228, 229, 230. Similarly, on an extended line with conduits 108, 109, 110, respectively, there are provided in the lower wall of feed means 201 openings or apertures 228a, 229a, 230a. . Conduit extensions 108a, 109a, 110a are preferably flexible hoses provided at their upper extremities with rigid pipe sections 128, 129, 130, respectively. It will be apparent that conduit extensions 108a, 109a, 110a may be made communicable with conduits 108, 109, 110, respectively, by insertion of the rigid sections 128, 129, through their respective aligned apertures in the duct walls of feed means 201.

Attachment of conduit extensions 108a, 109a, 110a to the feed means 201 so to to communicate with the respective conduits 108, 109, 110 may be accomplished by any convenient means, but are shown in the drawings, for purposes of illustration, as secured by means of threaded connections between rigid sections 128, 129, 130 and openings 228, 229, 230, respectively. It is apparent that conduit extensions 108a, 109a, 110a, may be readily removed from communication with the conduits 108, 109, 110, as byv merely unscrewing the threaded connection and withdrawing the extensions from the duct of feed means 201.

While conduit extensions 108a, 109a, 110a are shown removable from feed means 201 as a unit, to include the rigid end sections, an alternative embodiment would contemplate the permanent fixing of the'flexible portions of the conduit extensions with only the rigid sections 128, 129,- 130 being movable for insertion and removal into and out of feed means 201.

As described above, duct 212, which is made communicable with third feed means 301, is also selectively communicable with second feed means 201. In one preferred embodiment, as illustrated in FIGURES 2 and 3, this is accomplished by means of a pipe 211 which may be threaded into an aperture 211a in the bottom duct wall of feed means 201.

With reference to FIGURE 3, it will be apparent that, Where it is desired to remove one of the conduit extensions, such as 108a, the rigid end section 128 may be withdrawn from communication between apertures 228 and 228a and a suitable closure means 22% emplaced to close the opening 228a. Closure means 228b may be of any desired form, but has been illustrated here as a simple plate which may be clamped into place. Where frequent changes are made a permanently mounted movable valve may be employed. Similarly, where it is not desired to bypass material past unit 200 by Way of duct 212, it is necessary only to remove pipe 211, also illustrated as threadably attached to the duct wall of feed means 201, and close the aperture 211a with a plug 21112. Again, closure means 211b may take any convenient form, but is illustrated here as a male plug which is threadably insertable into aperture 211a.

For appreciation of the flexibility by which the compact apparatus of this disclosure is characterized in permitting changing with facility to any one of a plurality of material flow patterns, reference may be had to the schematic diagrams of FIGURES 4, 5 and 6.

In FIGURE 4, material from the hopper or first feed means 101 is split into two streams. Part of the material goes to the first unit to be separated into three distinct quantities which are then conveyed along the associated conduits to bypass both the intermediate and lower units. The portion diverted from the first feed means bypasses the upper unit and is in turn split, part going to the second unit for separation, and the other portion bypassing the second unit and being delivered to the third or lowermost unit for separation. The flow paths between the middle and lowest units are the same as between the upper and middle units.

In FIGURE 5, all of the material delivered from the first feed means is discharged over the first separation unit. The second separation unit refines only the thrown product of the first unit, while the third or lowermost separation unit further refines only the thrown product of the intermediate or second unit.

In FIGURE 6, the process is somewhat similar to that of FIGURE 5 in that the second unit refines only the thrown product of the first unit. However, the entire product from the second unit is then directed down and past the lowermost unit, while the pinned and midtiling products of the first unit are made to bypass the second unit and are discharged over the lowermost unit for further refinement.

While only those schematic flow patterns illustrated in FIGURES 4, 5 and 6 have been discussed in detail, it is apparent that a variety of further patterns may be readily obtained within the contemplation of the invention apparatus.

In accordance with the improved design of an electrostatic separator apparatus of this invention, there is also provided a novel electrode arrangement. This arrangement includes an electrode ladder, which comprises a bare electrical conductor, generally indicated at 10, which is disposed upright and adjacent an electrostatic separator assembly. Although not limited to such arrangement, the electrode ladder may preferably be disposed between two adjacent assemblies when two such assemblies are used together in a single apparatus. Thus, where assemblies including units 100, 200, 300 are disposed adjacent an assembly comprising units 100', 200', 300, it may be desirable to locate the ladder between such two assemblies so as to conveniently service both.

Enclosing conductor 10 is a duct 20. At the level of units 100 and 109 there are provided in the walls of duct 20 apertures 21 and 21, communicating with the space enclosing units 100, respectively. Likewise, at the level of units 200 and 200', there are provided apertures 22 and 22 opening onto the areas enclosing the two respective units at that level. Likewise, at the level of units 300 and 300', there are provided openings 23 and 23 joining the interior of the electrode duct with the areas occupied by the respective units at that level. Extending from conductor 10 are conductor arms 11, 11', passing through openings 21 and 21' and supporting electrodes and 105', respectively. Likewise, extending from conductor 10 are arms 12 and 12 which pass through openings 22 and 22' and support electrodes 205 and 205 respectively. Likewise, extending from conductor 10 are arms 13 and 13' passing through openings 23 and 23" and supporting electrodes 305' and 305', respectively. The conductor 10 is suspended between suitable insulator means, such as the porcelain insulators 14 and 15, at top and bottom, respectively.

The entire apparatus, including both assemblies, is enclosed by top and side walls. Thus, sidewall panels 31 and 31 close one side of the apparatus at the level occupied by unit 100 and 1%; sidewall panels 32 and 32" close opposite sides of the apparatus at the levels occupied by units 200 and 200'; and sidewall panels 33 and 33" close opposite sides of the apparatus occupied by units 300 and 3%. It will be understood that similar panel means close opposite sides of the apparatus in the plane of FIGURE 1. A suitable number of ventilating openings 34, 3'5, 36, 34, 35 and 36 are provided in the sidewall panel structure of the apparatus.

Located in some convenient space communicating with duct 29 of conductor 1t), .such as that space generally indicated at 24, there is provided suitable blower means oriented so as to draw air within duct 24 upwardly toward the blower and thence to the outside, as by way of exhaust duct 25.

It will be apparent that, with the blower means operating, air may be drawn through the ventilating openings in the sidewall panels; such air is then circulated through the areas enclosing the various separator units, and is then drawn through the openings 21, 21, 22, 22, and 23, 23 in duct 20. This flow of air which is illustrated by the arrows 37, in passing over the arms 11, 11, 12, 12, and 13, 13', and the upright portion of the conductor 10 cleanses the entire electrode ladder of dust and foreign matter inherent to the separation process. Removal of the duct in this manner improves efliciency and minimizes or eliminates short circuiting of electrical current. Furthermore, such dust which would ordinarily settle over other components of the apparatus may be continuously withdrawn from within the apparatus enclosure through the openings in duct 20, and evacuated to the outside through exhaust 25.

In view of the foregoing, it is apparent that the electrostatic separator of this invention provides a means for obtaining with speed and facility, great flexibility in the pattern of material flow through the apparatus, and hence wide selectivity in the specific process to which such apparatus may be applied. Moreover, the novel electrode arrangement and the provision for wind sweeping of the same provides an electrostatic separator apparatus which is reliable and requires little of the maintenance necessary in other apparatus of similar types.

While I have shown and described specific embodiments of the invention, it will be apparent to those skilled in the art that other embodiments may be adopted without departing from the scope of the invention; accordingly, I do not wish to be limited to the embodiments specifically set forth, but only to the claims which follow.

I claim:

1. An electrostatic separator assembly comprising a plurality of separator units arranged one above the other, housing means enclosing said units and having an inlet to admit air, an electrical conductor enclosed by an upright duct disposed adjacent said units, said duct having a plurality of spaced openings communicating with different ones of said units, each of said units comprising means including a pair of electrodes to electrostatically separate material into different quantities of varying characteristics, one of each pair of said electrodes being electrically connected to said conductor through the associated opening in said duct, means to feed the material to said separator units, means for separately collecting said quantities, and blower means to move air past said electrodes into said openings and through said duct to clean said electrodes and conductor of dust resulting from the separating operation.

2. The apparatus as recited in claim 1 wherein the other electrode of each of said pairs of electrodes comprises a grounded rotatable drum.

3. An electrostatic separator apparatus comprising first and second assemblies each having a plurality of separator units disposed one above the other, housing means enclosing said units and having an inlet to admit air, an electrical conductor enclosed by an upright duct disposed adjacent said units, said duct having a plurality of spaced openings communicating with different ones of said units, each of said units comprising means including a pair of electrodes to electrostatically separate material into different quantities of varying characteristics, one of each pair of said electrodes being electrically connected to said conductor through the associated opening in said duct, means to feed the material to said separator units, means for separately collecting said quantities, and blower means to move air past said electrodes into said openings and through said duct to clean said conductor of dust.

4. An apparatus for separating materials which comprises a plurality of separator units disposed in stages one above the other, each of said units comprising means to separate material into separate quantities of differing characteristics, first feeding means to supply the material to an upper one of said units for. separation thereby, second feeding means selectively communicating with said first feeding means and bypassing said upper unit to supply material from said first feeding means to a lower one of said units for separation thereby, means including a plurality of conduits to collect the separated quantities of material from said upper unit and convey said quantities downwardly from said upper unit in separate streams, each of said conduits being selectively connectible to said second feeding means to discharge material thereinto to be supplied to said lower unit and disconnectible from said second feeding means to bypass said second feeding means and said lower unit.

5. An apparatus for separating materials which comprises a plurality of separator units disposed in stages one above the other, each of said units comprising means to separate material into separate groups of different characteristics, first feeding means to supply the material to an upper one of said units for separation thereby, second feeding means selectively communicating with said first feeding means and bypassing said upper unit to supply material from said first feeding means to a lower unit for separation thereby, means including a plurality of conduits to collect the separated groups of material from said upper unit and convey said groups downwardly from said upper unit in separate streams, each of said conduits having a variable connection to said second feeding means to permit each conduit in a first condition of said connection to extend in a non-communieating relation through said second feeding means, thereby bypassing said lower unit, and in a. second condition of said connection to communicate with said second feeding means to discharge material into said second feeding means to be supplied to said lower unit.

6. An apparatus for separating materials which comprises at least top, intermediate, and bottom separator units, each of said units comprising means to separate material into separate quantities of differing characteristics, first feeding means to supply the material to said top unit for separation thereby, second feeding means selectively communicating with said first feeding means and bypassing said top unit to supply material from said first feeding means to said intermediate unit for separation thereby, means including a first plurality of conduits to collect the separated quantities of material from said top unit and conveysaid quantities downwardly from said top unit in separate streams, each of said first plurality 0f conduits being selectively connectible to said second feeding means to discharge material thereinto to be supplied to said intermediate unit and disconnectible from said second feeding means to bypass said second feeding means and said intermediate unit, third feeding means selectively communicating with said second feeding means below the connection thereto of said first plurality of conduits and bypassing said intermediate unit to supply material from said second feeding means to said bottom unit for separation thereby, means including a second plurality of conduits to collect the separated quantities of material from said intermediate unit and convey said groups downwardly from said intermediate unit in separate streams, each of said second plurality of conduits being selectively connectible to said third feed-v ing means to discharge material thereinto to be supplied to said bottom unit and disconnectible from said third feeding means to bypass said third feeding means and said bottom unit.

7. An apparatus for separating material which comprises a plurality of separator units disposed in stages one above the other, each of said units comprising means to separate material into separate quantities of different characteristics, a plurality of ducts to feed said material by gravity to each of said units, a plurality of conduits to collect separately said quantities from an upper one of said units and convey said quantities downwardly therefrom, each of said conduits having first and second portions, said first portion of each of said conduits communicating at its lower end with the one of said ducts feeding a lower one of said units, said second portion of each of said conduits having its upper end extensible through openings in said one of said ducts to rcmovably connect with said lower end of the associated first portion, and means to prevent flow from said openings when said second portion is disconnected from said first portion whereby quantities traveling in each of said first portions may be selectively discharged into said one of said ducts or bypassed through said one of said ducts by Way of said second portions.

References Cited in the file of this patent UNITED STATES PATENTS

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