US1020063A - Process of electrostatic separation. - Google Patents

Description

E. M. SUTTON & W. L. & E. G. STEELE. PROCESS 0F ELEOTROSTATIG SEPARATION.

APPLIGATION FILED JAN. ao. 1909.

1,020,063. Patented Mar. 12, 1912.

4 SHEETS-SHEET 1.

Allomey H. M. SUTTON L W. L. & E. G. STEELE.

PROCESS OP ELEGTROSTATIO SEPARATION.

APPLIUATION FILED JAN. 30. 1909.

Patented Mar. 12, 1912.

4 SHEETS-SHEET 2.

n TS A::E: \.S y m )M .05H w H. M. SUTTON & W. L. & E. G. STEELE.

PROCESS 0F ELEGTROSTATIG SEPARATION.

APPLICATION FILED JAN. 30. 1909.

1,020,063. Patented Mar. 12, 1912.

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[Nl/ENTORS. Hw'yhz. 51mm, Walei'l.. Steel@ 4 B Y Edu/2z 6. ,520820.

@fyi/m17 1 H. M. SUTTON & W. L. & E. G. STEELE.

PROCESS 0F BLBGTROSTATIO SEPARATION.

APPLICATION I ILED JAN. 30. 1909.

Patented 1111.111. 12, 1912.

4 SHEETS-SHEET 4.

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HENRY SUTTON,4 WALTER L. STEELE, AND EDWIN G. STEELE, OF DALLAS, TEXAS.

PROCESS OF ELECTROSTATIC SEPARATION.

Specification of Letters I atent Patented Mar. 12,1912.

Application led January 30, 1909. Serial No. 475,297.

To all whom 'it may concern:

Be it known that We, HENRY M. SU'rroN, WALTER L. STEELE, and EDWIN G. STEELE, citizens of the United `States, residing at Dallas, county of Dallas, and State of Texas, have invented certain new and useful Improvements in Processesof Electrostatic Separation, of whichthe following is a specification, reference beinghad therein to the accompanying drawing.

This invention relates toa process of electrostatic separation, and particularly to a process Where the comminuted material is supjected to the infiuence of an electrostatic fie d;

An object of the'invention is to submit the comminuted material, consisting of particles of different electrical susceptibilities to the action of an electric field of forceof unequal densities; said particles being delivered into the field at or near a point Where the electric charge has the least densitv.

' nother object of the invention is to ex pose such pulverulent material to the action of a suitable electrically charged conductor moving in a direction either the same as the line of travel of the material or in a different direction therefrom inI order to cause the material attracted by said conductor to change its position in the line of travel relative to other material not so attracted.A

A further object of the invention is to change the polarity or electric sign of the field of force of unequal densities in accordance with the preference shown by certain particles of electrical susceptibility to either the plus or minus field of electrification.

Other and further objects and advantages of the invention will be hereinafter fully set forth and the novel features thereof defined by the appended claims. Y

In the drawing :-Figure 1 is a plan view of one form of apparatus for carrying the process into'efi'ect; Fig. 2 is a longitudinal section on line 2-2 Fig. 1, showing the belt and table of Fig. 1 in elevation; Fig. 3 is a cross section on line 3-3 Fig. 1 with the electrical generator and connections shown in diagram; Fig. 4 is a diagrammatical planI of the table shown in Fig. 1 indicating the lines Aof travel of the different materials; Fig. 5 is a diagram of the traveling electrodes and table showing by dotted lines the action of the charges upon the particles.

Fig. 6 is a similar vievs7 showing the distribution of the charges upon the bars and table; Fig. 7 is a modified form of apparatus for carrying out the process by act-ing upon a falling field of material; Fig. 8 is a side elevation of Fig. 7; Fig. 9 is a plan of a further modified form of apparatus for carrying ont the process comprising separated tapering electrodes above the table; Fig. 10 is a detail elevation of one end of Fig. 9 with electrical connections; Fig. 11 is a detail of one of the electrodes showing the distribution of the charge thereon; Fig. 12 is a diagram of another modified form of apparatus for carrying out the process and consists of relatively fixed electrodes, and` Fig. 13 is a further modified form of appa-` ratus embodying a solid electrode disposed above the path of travel of the material.

We have discovered that when a mass of' particles of different electrical susceptibiliti-es are so placed that certain particles of the mass which may be more opaque to the lines of electrostatic induction than others will seek that part of the electric field where the static charge has the greatest density, while others will remain practically inert, or have a tendency to move toward a part of the field of lesser density. When this field of force is moved across the line of travel of the comminuted mass containing particles of different electrical susceptibilities, those having the greater attraction for" 'preference for one sign of electrification over the other. 'The separation may also depend upon a number of factors, one of the principal being the difference in the specific inductive capacity of the various particles.

The terms specific inductive capacity, dielectric capacity, inductivity, and dielectric coefficient as hereinafter used, are common in this art, to describe one and the same henornena. The'term density of charge and others of similar tenor hereinafter used are conventional ones employed in the art to. express what is believed to be, an increase in t-he static stress about t-he narrower or thinner edges of an electrostatically charged conductor.

vThe particles which tend to move in anl electric eld toward a point of greater density are those as a rule which offer the greatest obstruction'to the lines of electrostatic induction through them. They are also affected by the difference in their electrostatic capacity as some materials absorb vmore of a charge than others. The recess may also i be applied to separate particles of highconductivity from those which are classed as insulators, not by virtue ofthe fact that one is a conductor and the other not, but because those particles which are classed as good conductors are Yopaque to the lines of force of electrostatic induction which may also be Our process consists mainly in electricallyv inuencing a mass of particles traveling over a suitable deck or table, or even falling from ahopper, by means of an electric field having a portion of greater density than anf other portion thereof so that the particles Aeo are caused to travel in divergent paths. In the use of a moving charge-the waves of greater density travel -across the table and the line of travel of the particles thus electrically attracting one class of particles from among the others. This process differs from a dielectric treatment of the material where the dielectrics are polarized to such an ex- Atent that the polarization becomes suiiciently permanent so as to require an extraneous force to remove them from the separating electrode. ln this process there. is no convection of the charge from one electrode to another and it is essential that the electrodes be charged to such a-"degree of tension that there is no appreciable convection nor a disruptive discharge as the action of one electrode upon the other is entirely by induction.

lrior electrostatic processes have depended upon practically instantaneous excitation of the conducting particles to effect the separation, butin the present process the particles are practically immersed within an electrostatic field of action and retained there until separation is effected. ln this process all the particles have ample opportunity to be charged and it is not a question of difference in time of `charging the particles but the paths which they travel so that they may be separately collected. The particles are charged and discharged a number of times before they reach vthe end of their route by being attracted by first one electrode and then the other, although under the normal operation of the process but few of the particles rise to the electrodes but ride across the deck as if-supported upon a cushioning medium. j

For the purpose of effecting a continuous process the construction shown in Figs. 1, 2 and 3 is preferably used. 1n this form any desiredconstruction or arrangement of table may be used, for instance, as shown at 10, the upper surface ory deck 11 of which is" composed of good electrical conducting material, such as sheet metal. This deck is supported by means of a frame 13 resting upon" cross pieces 14. To each of these cross pieces a supporting spring 15 attached. the lower end of which rests in a socket 1G provided on the base 17, as shown in Fig. The portion 18 of the deck 11 is rendered adjustable by any suitable means, as shown in Fig. 3, so that the inclination thereof may be varied. One means for that purpose comprises the bolt 19 secured at its upper end to the deck, while its lower end passes through a support Q0 and has threaded thereon nuts 21 for adjusting the bolt and securing it in position. `When it is desired to raise the outer edge of this portion of the deck, the lower nut 21 is loosened and the upper nut adjusted upon the threaded holt, thus bendingor springing the side of the table slightly upward. At the edge of this adjustable portion a stop plate 22 is provided and extends for the entire length of the deck. This plate is formed of poor che trical conducting material or a dielectric. The object of the plate is to prevent the particles being pushed over the side edge of the deck 11 and to so modify the density of the charge on the electrode at `this point that none of the particles are carried by or beyond the plate when a traveling electrode. used. The opposite edge of the deck is provided with asimilar plate 23. In thisI form ofapparatus it is desirable to impart to the Amaterial a movement or travel by gravity and momentum longitudinally of the deck. The mechanical movement given to the particles is in the nature of propulsion or a throwing of the particles by which they arel given an impulse of forward movement in proportion to their frictional value when in contact with the supporting surface. This frictional value in particles of rough contour as compared with those of a smooth exterior is an important factor in an expeditious andv more perfect separation of such particles from each other and is utilized in in Figs.

are mounted by connection with the electrostatic feature of the process as a whole. It is particularly and clearly distinguishable from the mere carryingl function of a' mov-ing support. One means for accomplishing this is shown 1 and 2 Where the rod 24 is adjustably secured to one `of the cross pieces 14 by means of the threaded end 25 and the nuts 26 cooperating therewith. The opposite end of the rod is provided with an eccentric sleeve 27 Within which an eccentric 28 is disposed. This eccentric is mounted upon the driving shaft 29 adapted to be driven by the pulley 30.

For the purpose belt 31 extends from the pulley 30 to a pulley 32 upon the shaft 33. This shaft also carries a cone pulley 34 provided with a belt 35 connected to shifter 47 and extending to an oppositely disposed cone pulley 36 on the shaft 37 which is also provided Vwith a driving pulley 38 from which the belt 39 extends. For the purpose of feeding comminuted or pulverulent material to the table a hopper 40 is disposed atone end and near one side thereof as shown in Fig. 1. This hopper -is provided with a shaker pan 4l from which an actuating rod 42 extends to the eccentric 43 mounted upon the shaft 44. This shaft is driven by means of the pulley 45 from which a belt 46 extends. ing a convenient means for producing a moving field of force of different densities, a series of bar electrodes 50 are provided and fastened in any suitable manner to the outer surface of the series of belts 51, these being mounted on pulleys 52 which are insulated from the shafts 53 upon which they collars 52) surrounding the shaft as shown in Fig. These belts should be composed of electrical conducting material or coated with such material upon the face where the bar electrodes are applied in order to maintain all of the bars at the same potential. This belt travels laterally of the direction of feed or travel of thematerial duc to the movement of the table, and the belt may be driven by any desired means, for instance., as the pulley 54 on shaft From this pulley belt 55 extends to the pulley 56 on the shaft 57 of the cone pulley 58. A coperating cone 59 is provided and connected with-cone 58 by means of belt 60. This belt is adjustable to determine the speed of travel of the bar electrodes by means of the belt shifter 61.v This adjustlnent is important as the travel of thc electrodes must be in proportion to the movement of the table and the consequent feed of material thereon as well as the time required for the separating action due to the electric susceptibility of the particles. The shaft 62 of the cone 59 may be driven by any suitable, connection. as shown at 63. 'lhe shafts upon which the electrode belt is mounted of speed regulation a As show-` may be supported by any suitable form of framework, for instance, as at 64. This frame carries bearings 65 for the shaft 63. The tail or delivery portion of the table is provided with a downwardly inclined delivery plate 66 which is formed with a bar 67 spaced above position the directing boards 68 which are disposed in proper position to receive and direct the zones of separated material to proper rece tacles.

Variousv orms of electrical charging apparatus and connections may be used for producing the electric field from the bars. One. form is shown in Fig. 3 and comprises the generator 70 from the minus side of which a conducting line 71 extends to the bar 72 forming part of the reversing switch 73. The terminal button 74 of this switch is connected by line 75 toIone terminal 76 of the resistance gap over which the charge passes by convection to the opposite terminal 77 and thence by line 78 to the wiper 79 which contacts with the electrode bars 50. By thismeans a minus charge is im* parted to the bars for use when the material treated demonstrates a preference for that polarity. Then the plus polarity of the generator 70 is connected to the ground through line 80 extending to switch bar 81 of the reversing switch 73 and thence to the switch button 82 and through line 83 to ground. When it is found desirable to send plus charges to the har electrodes 50, the switch bars 72 and 81 are moved until the former rests on'the button -82 and the bar 81 rests upon the button 85 which is in circuit by line 86 with the line 75 leading to the electrodes. The charge will then pass from the plus side of the generator by means o the line 80 to bar 81 through branch line 86 and line 75 across the resistance gap and by line 78 to the, wiper 79 contacting with the har electrodes. The terminals `7 6 Vand 77 of the resistance gap are adjustably mounted in their supports 87 so that the gap luay be increased or diminished at will to vary the amount of charge supplied. The charge passes across this gap by convection in the well known manner and is simply intended to keep the potential of thc bar electrode to the desired tension- The. gap is regulated to supply the amount of electricity to the bar electrodes when charged that they would lose by leakage. Any other desired form of resistance suitable for high potential currents could be used in place of this gap. lt is preferable but not absolutely necessary that the metal deck of the table. be connected to ground and this may be accomplished by means of a line 88 connected to the table deck. The grounding of the deck has the advantage that the `separation is mostly carried out by the induced or bound charges traveling the same so as to retain in across the deck, and avoids the pressure of a free charge upon such portions of the deck, table and other parts of the machine as do not directly enter linto the process of separation. The grounding of the deck is equivalent to its connection to the opposite pole ofthe generator to that from which the electrode bars are charged. y

In Fig. 4 a diagram of the deck 11 is shown and the. portion from the line- 90-1--90 to the edge 91 is inclined upward as at 18 in Fig. 3. The adjustment ot this portion of the table restrains in some cases the too rapid cross travel ot the particles under the influence of the traveling electrode. The inclination of the deck tends to force them backtoward the center. The relative position of the belt of bar electrodes and the area covered thereby is indicated by dotted lines 92, the direction of movement of the belt being toward the edge 91 of the table. As indicated by dotted lines, the material least aifected by the travel of the electric ield of greater density thereover will be delivered in an area such as indicated at 93, while that slightlymore affected will be discharged over the deliveryl board in an area indicated at 94, while that most affected and comprising the particles which have followed the greatest density of field are delivered at 95. A I 4 Theelectrieal conditions ofthe bar electrodes is indicated by diagrams in Figs. 5 and 6, the dotted lines in the latterv figure showing the relative distribution of the charge, the greatest density of which exists at the under :tace of the bar next the material as indicated at 96 and the least at the opposite face 97. This produces corresponding charges by induction of the-opposite sign on the deck immediately below the.

bars as indicated by dotted lines at 98, the greatest density being at this point and the less at the intermediate point 99 opposite the space between the electrode bars. 'This charge upon the' deck is usually termed an induced or bound charge, that is, the -deck is not charged as a whole but only that Vportion of it immediately facing the electrode bars. moved in the direction indicated by the arrow that the peaks 98 of the charge upon the deck will likewise shift or travel with the1 same rapidity.` It will thus beA seen that the charges are moving across the deck in peaks of different densities at an angle to the travel of the particles imparted by movement of the table. Those particles which are most susceptible to the action of the Imoving charge are consequently dragged out of the line of travel that they would otherwise take were they onlysubjectcd to the propelling laction upon the table.` It is-preferable to .accurately regulate the movement of the electrode bars across the table and also regu- It is evident that if these bars are 'the purpose of illustration as unless the particles are very strongly attracted by placing the bar electrodes close to the deck, and thus increasing the potential between the particles and bars, the particles do not ride up through the bars as shown, but ride over the table apparently on the peaks of the moving charges 98 99, Fig. 6, as if suspended in an extremely elastic medium. vThe highly attracted particle 100 is drawn upward upon approximately a curved line as indicated at '101 toward the traveling eld of greater density and passes into the space between adjacent fields thus permitting the return of the particle toward the deck but effecting a continued movementthereof toward the edge of the deck. The particle indica-ted at 102 has only a slight attraction and its movement is generally straight up and back to its place of starting or\toward a weaker portion of the lield. Under normal conditions the electrode bars exert only .suticient energy to divert some of the vparticles from their otherwise'straight line of travel from the :teed hopper to the point of delivery.

In Figs. 7 and 8 a modiliedform of apparatus for carrying out the process is shown and consists in disposing the bar electrodes or their equivalent as described in connection withFigs. l, 2 and 3 in position to act upon a falling body of comminuted material and to divert some particles thereof during their movement in order to separate them from others. vIn these figures the bar electrodes are indicated by 104 and connected together asl described in connection with Figs. 1, 2 and 3 to form a continuous belt which is mounted upon rollers 105 at opposite ends and driven by any desired means, for instance, a driving belt 106. Opposite the bar electrodes is a stationary plate electrode A107. The material is fed between these electrodes from a hopper 108 and falls in a stream which is deflected laterally by the action of the moving electrode so as to be deposited in a series of separate receptacles as indicated at 109. The bars are charged from a generator as described in connection with Fig?) by means of the wiper 110 while the plate 107 isconnected to ground by a line 111. The relative travel of the particles under the influence of the two electrodes is shown in Fig. 8.

apparatus for carrying out the process in whichl a. series of separated electrodes ,are

a suitable framework and spaced a short distance above the deck as shown in Fig. 10. This deck is also connected by line 114 with the ground with whichA the opposite side of thel generator 115 is also connected by means of line 11G. When these plate electrodes 112 are connected to a high potential source of electricity the charge distributes itself as inlmes in Fig. l1 where thev dicated by dotted greatest potential or density is present at the smaller end of the electrode as indicated at 117, While the remainder of the charge is distributed at less density and surround'- iug the edges of the electrode as indicated at '118. The separation and` delivery under this construction is substantially the same as described in connection with Fig. 4 the,

feed being from the hopper at 40 Where the particles are delivered in approximately the Weakest part of the electric eld of the first electrode of the series. Ihe deck is given a reciprocating motion as described in .conneetion with Figs. 1 and 2 and as the particles are propelled along ythe deck those in' the mass which naturally .seek the electric field of greater density are drawn out froml among thegeneral mass toward the tapered end of the electrode 112 and are delivered in the area 95 as described in connection with Fig. 4. Others less affected are delivered in the area 94 While those least affected are delivered at 93 and in this manner the particles are separately collected. In Fig. 12 a form of apparatus for carrying out the process is shovvn and embodying spaced fixed electrodes connected to thel opposite poles of a generator. In this form the charging elecfrode 118 is formed of metallic screen cloth ,the screen and at 123 on the plate.

having relatively large openings between the meshes, While the opposite electrode 119 is formed of an electrical conducting plate, preferably of metal. Both the screen and plate are connected to the yopposite terminals 120 of a high tension source of electricity by means of the line 121. When the screen and plate are thus charged, the static charge distributes itself on their surfaces unevenly; the charges accumulating at a greater density around the edges of the screen 4and plate than at the centers thereof. This distribution of the charge is indicated by dotted lines showing the greatest density at 122T on he particles 124 and`125 shown upon the plate 119 are of diverse electrical susceptibility` and thepartiele 124 Works'its way toward the edge of the screen and plate where the movement generally charges have their greatest density, passin up through the screen in its course o trave as indicated by the 'dotted 'lines"126. The less attracted particles 125 has only a slight directly upward and back to its place of starting or toward a weaker part of the field.

In Fig. 13 a solid form of charging elec trode is shown at 128 which may be stationary. In this form the material to be separated is 'fed upon t/hetable 129 at the center thereof or in the field of Weakest' density Yof the electrode, as the greater density is present at the side edges thereof as indicated by dotted lines 130. The . particles 131 and 132 being delivered beneath the center of the electrode 128, it is evident that those of greater attraction will seek the outer edges of the electrode Where the field of greater density exists. The movement .of the particle 131 is indicated by dotted lines 133 while the particle 132y remains substantially in the field of least density of charge and travels therethrough in the movement of the table which is similar to that described in connect-ion with Figs. 1 and 2.

The operation of the process as effected by means of the preferred form of apparatus as shown in Figs. 1 to 3 1s as follows z-The materials to be separated are fed from the hopper by means of the shaker pan thereof to the deck of the table which is given a reciprocating motion and on account of the inclination of the supporting `springs thereof rises diagonally on its forward stroke and recedes in the same line on its return stroke. This'has the effect of propelling the particles longitudinally of the table. The bar electrodes being driven as described the direction of their travel is transverse to the travel of the particles and on the under side of the belt next the table from the feed side toward the opposite side thereof. When these bars are charged as described, the par-` ticles travel across the table in divergent paths from the hopper to the delivery end as indicated by dotted lines in Fig. 4 at which point they are separately collected.

Heretofore, in the art of electrostatic separation of comminuted material it has been found essential to so deliver the par ticles to a charging electrode that only the superior conductors of the mass will be charged and repelled before the nonconductors can be affected, this feature being quite essential to the-success of those processes for if all the particles were allowed to remain sufficiently lon under the influence of the static charge te particles of lesser conductivity would also become charged and repelled thus defeating the process of separation. In the prior art the particles are introduced at once upon the electrode where the static charge has the greatest density. In Aour process the particles are delivered into the electric field where the charge has the least density or the field of greater density is moved across the line of travel of.

the particles.

In Dthis process the time required to elec-- trify conducting or nonconducting particles is not essential but the separation Iis determined by the electrical susceptibility of the particles in an electrical field having a greater density of charge at one point than at another, and this susceptibility may arise have the greatest electrical susceptibility,l

and are carried toward the field of greatest density and up the inclined portion of the deck in opposition to the force of gravity leaving the lighter particles on the lower plane of the deck.

While this process acts primarily upon the dielectric properties of various substances it does not carry the polarity ofthe dielectrics to a point where they become set but leaves them free to move within the cenfines'of the electrostatic field of action.

The separation produced by this process may be effected by electrodes of -di'erent form from those shown or by a dierent form of apparatus than herein "disclosed, and the polarity of the charge fed tothe particles is also important because of the preference demonstrated by some particles `for a cer-` tain polarity is a most important factor in producing successful separation vand therefore means are provided by which the polarity of the electrodes may be changed to that most efficient for the material treated. As above described in the use of transversely moving electrodes some of the particles are moved toward the edges of the table where the greatest density exists. It is not the intention of the present' invention to lift the-particles into contact with the moving electrode, but to merely raise them slightly above the-deck so that 'they may be supported as upon Aan elastic medium and in such electric fieldffmoved into a separate track or zone vcapablejiof independent collection from Athe remainder ofthe material not so`electrically attracted.,

Without restricting the invention, it seems' proper to state thatit utilizes an electro.- static Held ink presenting-A.':particles` to the weaker portion thereof when some particles are moved therefrom and along the lines of force to a stronger portion of said field and from any other of the particles. Further it combines with this movement of the particles by such lines of force the force of' the two forces employed.

Having described our invention and set forth its merits, what we claim and desire to secure by Letters Patent is 1 l. A process of separating comminuted materialv consisting in imparting a normal movement of the material 'upon a support, establishing an electrostatic charge of varying strength upon the support across the line of normal movement to cause the different components to travel according to their susceptibilities upon the support in lines deviating from the line of normal movement. u'

2. The process of separat-ing comminuted' material consisting in establishing an extended electrostatic charge varying in den: sity along its Iextent sucient to deviate the more susceptible material from the normal lineof movement into a travel in the direction of increase of density and feeding the material into the field of such chargein proximity to the region ofy weakest charge.

8. The process of separating comminuted material which consists in feeding said ma` terial into an electrostatic charge variating in charge density toa degree sufficient to deviate' the susceptible particles, and feeding the material into'ithe field of such charge in proximityI to the region lof the lowest charge of density and in a direction lateral to the normal path of the material, and separately collecting the particles thus separated.

4. The process of separating comminuted material consisting in imparting a traveling movement tothe material upon a support, establishing upon the support an electrostatic field of density varying alongthe line of support in a line'intersecting, the normal path 'of travel and of strength sufficient to cause the susceptiblematerial to.

travel upon the support in lines deviating from the normal line. oftravel and extend- Ling across vsaid support andfrom a portion of said field oflesser density to afportion of greater density,y and separately collectingthe -separated particles.

` 5. The process of separating comminuted material' consistingin establishing upon a support ani. electrostatic. field .of r'varying density across the support and sufficient to impart la movementf of .the more susceptible particles along the 'surfacein'the direction ofincreaseof st1{ess,` delivering comminuted "material to be separated to the surfaceat the weaker portionof the field5'and separately collecting the separated particles.

6. The process of separating comminuted material which consists in moving the ma- `and of degrees the electrode to the region of denser charge,

and separately collecting the thus separated particles.

8. The process of separating comminuted material consisting in feeding the same to an of unequal density and electrostatic charge moving some of said particles by the influence of said charge along the lines of increasing density and across their normal path of travel, and separately collecting the separated particles 9. The process of separating comminuted material consisting in creating upon a surface lan electrostatic charge of unequally distributed density, feeding material to such lsupport and imparting an impulse in one direction to sald material, shifting the points of greatest density and therewith the more susceptible material in another direction upon the surface.

10; The process of separating comminuted has particles of different mittin the material to an electrostatic field extending' in planes approximating parallelism With the line of normal movement of the material and continuously and unidirectionally shifting the lines of greatest density of said field in al direction deviating from that of the normal movement of the material, and separately collecting the thus separated particles.

11. The process of separating comminuted material consisting in supporting said material and submitting particles thereof of. different electrical susceptibilities to the Separating action of an electrostatic `field y greater densities of said fiel extendin 1n planes approximatin(lr parallelism wlth the support and line ofj normal movement of the material and continuously and unidirectionally yshiftin the lines of in a direction deviating from that ofthe normal movement of the material, moving the particles relative to their support While in 'said field, and yseparately collecting the separated particles.

12.-' The process of separating comminuted materials consisting in establishing an electrost-atic field of varying density upon a support, with maximum densities 'in separated areas and delivering such materials to the support, moving the more susceptible material to regions of greaterdensity upon said support, and separately collecting the so separated materials.

13. The process of separating comminuted materials consisting 1n establishing sepa-v rated electrostatic elds each of varying density upon a support, feeding the material to be separated to said fields, shifting said fields and therewith the more susceptible material to other portions of said support, l

and separately collecting the thus separated material.

14. The process of separating comminuted material consisting in establishing separated electrostatic fields each of varying force and of the same polarity on the support, feeding material to such support and moving it thereon, shifting the fields and therewith the more susceptible material to other portions of said support, and separately collectingv the so separated components.

15. The process of separating comminuted materials consisting in establishing upon a support separated movable fields of lsimilar polarity each of varying density along the support and traversing theline of normal travel of the materials, intensifying said fields at yone side of the line of normal travel of the particles, and separately collecting the so separated particles.

16. The 'process of separat-ing. comminuted material consisting in submitting particlesv of different electrical susceptibilities to the action' of an electrostatic field of maintained polarity extended in planes approximating parallelism with the line of normal movement of the material and continuously and unidirectionally shifting the lines of greater density of said field in a direction deviating from' that of the normal movement of the material, and separately collecting the separated particles.

. 17. The process of scparatingcomminuted material consisting in submitting particles of different electrical susceptibilities to an electrostatic field of maintained polarity extending in planes approximating parallelism with the line of normal movement of the material, continuously and unidirectionally shifting the lines o said field in a direction deviating from that of the normal movement of the material, feeding said particles into the weaker portion of said field, and separately collecting the separated particles.

18. A process of separating comminuted materialconsisting in establishing upon a support an electrostatic field ofvarying density between opposing electrodes and electrically moving the more susceptible particles across their normal path of travel and above said support over a portion of lesser density along thelines of force to a portion greatest densities of of greater density, and separately collecting the thus separated particles.

19. A process of separating comminuted materials consisting in establishing a unidirectionally moving electrostatic lield ot varying density between opposing electrodes, one of which serves as a support for the material, moving'the more susceptible ol" the particles across their normal path of travel and aboie said support from a portion of said tield of lesser density along the lines of force to a portion of greater density, and separately collecting the thus separated particles.

20. The process of separat-ing comminuted n'iaterial which consists in subjecting the same tc the action of a unidirectional electrostatic tield of unequal density and Changing and maintaining the changed polarity ot said field in accordance Wit-h the preference of some of the particles to a particular polarity.

21. The process of separating comminuted material whichy consists in submitting the saiii'e'tol"`tlie action of an electrostatic. ield ol unequal density disposed across the normal path of said material whereby the particles oit said material are separated from each other in accordance with their respec` tire susceptibility to t-he varied density of said tield. f

QQ. The process of separating comminuted material which consists .in submitting the same to the action of a unidirectionally moving electrostatic field of unequal density disposed across the normal path of said material whereby the particles of said material are separated from each other in accordance with their respective susceptibility to the varied density ofV said tield andare caused to travel in separated paths.

ln testimony whereof We aiX our signatures in presence of two Witnesses.

HENRY M. SUTTON. 1WALTER L. STEELE. EDVIN G. STEELE.

Witnesses as to H. M. Sutton:

ALFRED T. GAGE, LEWIS HoDGEs.

wWitnesses as to Walter L. Steele:

H. A. BLOMGREN,

E. M. CHRISTIAN. v lVitnesses as to EdWinGr. Steele:

WV. A. MIDDLETON,

JAS. O.'BALDWIN.

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