US859998A - Method of electrical separation. - Google Patents

Description

PATENTED JULY 16, 1907.

F *No. 859,998.

H. A. WENTWORTH. METHOD OF ELECTRICAL SEPARATION.

. APPLICATION FILED DBO. 20, 1006.

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*No. 959,999. PATENTED JULY 19, 1907.

9 H. A. WENTW'O'RTH. METHOD OF ELECTRICAL SEPARATION.

APPLIOATION FILED D E0.20, 1906.

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PATENTEDJULY 16, 1907. H. A. WENTWORTH. METHOD OF ELEG'IRIGAL SEPARATION.

APPLICATION FILED DEO.20,1906.

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PATENTED JULY 16, 1907.

H. A. WENTWORTH. METHOD OF ELECTRICAL SEPARATION.

APPLICATION I'IILED nno.zo,19oe.

4 SHEETS-SHEET 4.

INVERTE UNITED STATES PATENT IC HENRY AZOR WENTWORTH, 0F LYTNN, MASSACHUSETTS, ASSIGNOR TO HUFF ELECTRO- STATIC SEPARATOR COMPANY,- OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE; A

warrior) 0]? nnEo'rnroAn SEPARATION.

' l 'ate'nted July 16, 1907.

Application filed Deoember20,1906. Serial No- 348,720.

To all whom it may concern:

Be it known that'I, HENRY Az'on WENTWORTH, a citizen of the United States, and a resident of Lynn, in the county of Essex'and State of Massachusetts, have invented new and useful Improvements in Methods of Electrical Separation, of which the following is a speci fication;

My invention relates to the art of electrical separation, concentration, or classification, of the ingredients of heterogeneous mixtures of solid comminuted matter such as, for instance, the miscellaneous components of ore bearing rock or earth in which, as is often the case, there may be several substances of graduated:

value which to beeffectively and economically,recovered must be separately classified or concentrated and freed from the earth, rock or other gangue wherewith they are associated in nature. x

My invention consists in an improved method by which these results can be accomplished and by which 20 the segregation or concentration of several elements in a mixture may be successively effected.

My method involves to some e'xtent the practice of theprocess shown and described in Letters Patent of 'the United States No. 805,694 datedNov. 28, 1905,

paratus' granted to Philip Henry Wynne; and in the which I have found to be best'adapted for the performance of my new process, I employ the devices and method shown and described in Letters Patent No.

796,012 ,to Greenleaf W. Pickard, dated August 1,

' In conducting a long seriesof experiments and demonstrations with an apparatus constructed and operated according to the specifications of the above mentioned Wynneand Pickard patents, and containing also the structural peculiarities set forth and described in Letters Patent of'the'United States No. 801,380 to Charles H. Huff, dated Oct. 10, 1905, I modified and .varied theconditions of; operation, both in respect to and I was at first led to regard thisadhesion asmore or less detrimental to the proper conduct of the process;

I have been informed thatprocesses and apparatus for electrostatic separation have been contrived and operated wherein the electrical conditions are such that some ingredients of the mixture to be segregated or concentratedare made to adhere to an electrode by reason of their-property ofdielectric hysteresis, and while the. electrical conditions of'the Wynne process hysteresis of such particles.

under which I was operating are radically different from those which must be maintained for the purpose of the aforesaid hysteresis process of separation, I supposed or rather assumed at first, that the adhesion of some particles under some conditions during the performance of the Wynne process might be due to the On closer observation, however, this hypothesis failed of verification.

During the performance of the Wynne process there had appeared under some conditions a clearly defined band of pale violet light between the two electrodes of the apparatus, this band of light being located in 00- manifested their most pronounced tendency to adhere to the electrode; and moreover, on experimenting .with crystalline quartz particles, which possess subingthe same conditions of potential as under ordinary atmospheric conditions had produced the band of light,

I found that inferior conductorswhich, under the ordinary atmospheric conditions had adhered to the main electrode, no longer manifested any tendency so to do -but fell therefrom as inertly as though no electrical conditions whatever had been imposed. Under these conditions if dielectric hysteresis had been responsible for the phenomenon ofadhesion, the dielectric particles would have clung to the electrodes just as emphatic ally as under the ordinary atmospheric conditions. I discovered during the course of these investigations that 'phere pressure which so varied the dielectric strength ofthe air surrounding the electrode, that the band of violet light no longer appeared, meanwhile maintainthe highly concentrated electrical field produced by i the Wynne or Pickard apparatus ionized the-air directly in or near the region of highly concentrated field, and by ionizing the gas further exerted the convective effect of the field so as to produce a transference of the ions from one electrode to the other in a jet of almost inconceivably high velocity. This jet in the form of apparatus used (two parallel electrodes, one a cylinder and the other a glass covered wire) was in form a thin sheet or band extending across from one electrode to the other. Each one of the ions in this jet is, in efiect, afminute fraction of the charge on the electrode from which the jet proceeds,-'or, perhaps, more accurately speaking, servesas a carrier for a small portionof the said charge, and'is effective therefore, to transfer from one electrode to the other an infinitesimal fraction of the charge on the electrode.'

As a result of my investigations very briefly summarized above, I have invented a process of electrical separation which I proceed to describe in connection with an apparatus appropriate thereto which is shown in the accompanying drawings.

In these drawings, which are diagrammatic for the purpose of clear illustration,-Figure 1 shows an apparatus for electrical separation, which depends primarily upon the effect of a jet of ionized air upon the particles of a heterogeneous mixture of solids; Fig. 2

- phases; and Fig. 8 is a similar detail on a large scale showing the operation of my process in another of its phases.

Referring to Fig. 1, E is an electrode cylindrical in form and composed superficially, at least, of a good conductor such as steel, brass, or copper. The electrode E is mounted upon a shaft e and is rotated in a direction indicated by the arrow. H is a delivering hopper from which the comminuted mixed solid material M is delivered in a thin stream upon the surface of the electrode E. In Fig. 1 I have shown the hopper H as delivering the material M upon the rising surface of the electrode E. The line of delivery of material should beso arranged with respect to the character of the surface of the electrode E and its speed of rotation, that any tendency of the material to slip down the electrode surface in a direction opposite to its direction of rotation will be overcome by the movement of the electrode itself, and all the particles be conveyed upon and with the rotating surface. E is an electrode opposed to the electrode E and is preferably composed of fine copper wires inclosed each in a dielectric envelop, such as described in the Huff patent above mentioned. The electrodes E and E are intermittently connected respectively with the two terminals of a source of electrical energy. The energizing apparatus shown in Fig. 1 is the same as that shown and described in the Pickard patent above mentioned, and consists of a primary source G which may be an ordinary alternating current generator. The circuit of this generator includes the primary 1 of a transformer coil, the second- .ary of which, S, is connected to the terminals of a condenser K, a resistance 1 being interposed to damp or muffle any oscillations which may be produced by the secondary. Thus, as set forth in the said Pickard patent, the condenser K becomes the immediate source of electrical energy for the electrodes in the separator The wire 14 leads to a spark gap P which in this branch separates the condenser K from the electrode E, and the wire 13 of the other branch leads directly to the surface of the larger electrode E. A noninductive resistance R serves as a bridge between the "electrode connections to deplete the electrodes of potential the instant after they are charged by the break-down of the spark gap 1.

In order to avoid the effect of transporting alternating charges by. the stream of ions, the apparatus commutator or rectifier x. A complete description of this operation will be found in the Wynne and Pickard patents above mentioned. Its result is to produce at the electrodes E and E periodic accessions of potential which are separated in time by intervals of substantially no potential.

The electrode E being set in motion and the supply of material M being delivered continuously from the hopper H, and the electrical apparatus being put in operation, the material M distributed in a thin layer on the electrode E moves into the field produced by the electrodes E and E. This field, by reason of the design and construction of the electrodes and their close proximity, is practically concentrated to a thin band extending from the wire electrode E to the surface of the larger .elect'rode E.

When the potential difference between the two electrodes E, H is raised sufficiently, say to 15,000 volts, the band of violet light will manifest itself in the -concentrated field, indicatingthat theionization of the' air has reached that stage necessary for the passage of a spark discharge. The dielectric envelop surrounding the electrodes E (Fig. 1) operates 'to prevent too great a quantity of electricity passing in each spark, and thus the discharge is drawn out into a band of very minute and closely spaced spark discharges.

The jet, however, is produced under electrical conditions in which the potentialdiffcrences are very much less than those required for the manifestation of visible light in the concentrated field, and even under such electrical conditions my process of electrostatic separation may be carried on, although I prefer to employ the apparatus under conditions of structure and adjustment which insure the appearance of the violet illumination. The result of the jet of ionized air is to convey a charge to the particles on the electrode E. Those ingredients of the mass M which are of superior conductivity, by reason of their more or less intimate contact with the electrode Edeliver their charge to the electrode, or, to speak more correctly;the charge on the conductive particles of the mass M received from the jet proceeding between the two electrodes is almost instantly neutralized bythe charge of opposite sign residing on the electrode E. The non-conductive particles, however, as they resist conduction through their mass and also manifest much less surface leakage than the conductive particles, 'receive the charge from the ionized gaseous jet only on their exposed sides, and consequentlycarry each a local charge characterized by potential different from that of the electrode E, whether the latter be actually charged or be for the time inert. Consequently theinferior conductors of the mass adhere to the electrode E and continue to adhere thereto after the rotation of the electrode E has carried them out of the'field between it and the electrode E. As the mass M is carried on the electrode over its descending limb, the conductive particles which received but immediately surrendered the charge conveyed to them by the ionized gaseous jet, are inert and free to fall from the electrode as soon as the inclination of the surface on which the particles rest becomes sufliciently steep, as at m; the inferior conductors on the contrary, each of which continues' to carry its local charge on the surface not in electrode E, so that after the particles of the -mass M- have been conveyed through this concentrated field they rest upon asurface which, electrically considered, is inert; This may be demonstrated by providing, as shown in Fig. 1, an electrical screen, such as the sheet metal plate N which, for the greater part of its surface, is parallel and close to the surface of the electrode E and electrically connected thereto as by a wire n.

Sucha screen will effectively prevent the appearance or'manifestation of potential on the surface of the electrode shielded by it; the behavior, however, of the particles is not perceptibly different whether the screen be in place as shown or not. v

The operation of itlie Wynne process requires con ditions under which the conductive particles of the mixed mass assume the charge of the electrode in contact with which they rest so that they are vigorously repelled from that electrode. When, however, the electrical conditions'are adjusted in respect to potential and duration of charge so that this repellent efiect is not perceptible, that is to say, if manifested at all, serves only to barely neutralize the efiect of gravitation, nevertheless by the operation of the ionized gaseous jet the inferior conductors are locally charged 'in' r -the manner above described, whereas the conductors ductors after their subjection to the ionize being completely superficially charged by the said jethave their charge neutralized by their contact with the electrode on which they rest. Thus in Fig. 1, I have shown-the electrodes E as directly over the top of the rotating--electrode E so that if the electrical conditions were such as to bring into play the auto-repul- 'sion of the Wynne process, the conductive particles would only hop a little way from the surface of the electrode E and return thereto. In practice, however,

' I find that by either diminishing the potential differ- .ences or by reducing the time duration oi the poten-* vti al accessions until no convective response by con-' ductive particles is perceptible, nevertheless the separative efiect due to the adherence of the inferior cond gaseous jet is carried on with certainty and success. I

As the ordinary mechanical devi ces such'as brushes or scrapers have given trouble inmemo ving adhering particles from an electrode, I employ the electrical; stripper shown in Fig, 1. This consists of a wire electrode which may be covered'similarly to the electrode E, or preferably, a grid of such electrodes as shownat E The exciting apparatus for these electrodes need not contain any'interrripting and depleting vices but may, sis-shown, consist merelyof the wires, 3, 4, connected to the terminals of-these'condar'y 8*, which is provided with the oscillation suppressing reof the potential accessions at the electrode Ef is protracted far beyond the duration of, thepOtentiaL ac: cessions of the electrodes excited 'by' such apparatus as that described above in connection with the elec} trode When, therefore, theadhering poorly con-- & 1

ductive particles come within the field of the electrode E they are subjected to the direct influence of the charge on the electrode for so long a time that even though they are composed of highly resistant substances, they become charged with potential similar in sign to that of the electrode E, and are repelled process and apparatus, this auto-repulsion being sufovercome, the effect of charge conveyed by'the ionsired, be excited-by a source of substantially steady potential, such as an electrostatic machine.

Poorly conductive ingredients of the mass M are shown as falling from the electrode E at d and a partition or separator D may be employed to perpetuate the separation of these particles from the others. 4

It is frequently the case that even after the operation of the electrical stripper .there are some very minute particles still adhering to the electrode, and these are readily removed by a brush or scraper such as B and fallas at d into whatever receptacle is provided for them.

through the deposition of local charges by the action "of the ionized gaseous jet upon inferior conductors in a mass may, under many conditions, be effective for electrical separation or concentration without the modification of the Wynne process by my ionization process and the combining of the two processes or. agencies will be found preferable and effective overv a larger range of material conditions'than either pro cessemployed solely. Moreover, the cooperation of the two processes results in a mutual improvement of functional periorrnance so that the auto-repulsion process of Wynne-is enhanced in its effects by the super-position or cb-ordination of my process of local 'versely, my process is enhanced and improved in its efiects and functions by the cooperative employment of the principle of the Wynne process' a In Fig. 2 I have shown an apparatus whereby the fundamental principles of the Wynne process and of my ionizing process"co6perate.- By this cooperation. it, is possible and commercially practicable to effect a ingredients of a mixed mass withmuch, greater certainty and rapidity than heretofore. In Fig. 2 H represents a hopper slotted at the botand-,isubstantially continuous stream to the surface "of. thecylindrical electrode E which is mounted upon ashaft e and caused-torotate in the direction of the arrow shown-"The opposed electrodes'Ef, E fiE E consist each of a wire ;or wires each of which may "be inclosed in a dielectric envelop as of glass, the several members of each-of these opposed electrodes being constructedsubstantially in accordance with the specifications of the Huff patent, N0' "801,38 0,1

one of the members of the opposed electrodes shown *Qsp'aced apart, so that the field of either does not affect the field produced by another. The close proximity,

ficiently emphatic first to neutralize, and then to aid of other agencies; I'believe, however, that the" 95 charge by ionization of the intervening gas, and, con- 7 therefrom in the manner characteristic of the Wynne ized gaseous jet. The stripping electrode may, if de- While my above described process of separation I serial and graduated classification of the heterogeneous te'm from which the material M is delivered in a thin .wherein the electrode marked E is similar to a single herein. The several electrodes E(, E E, E are of the members of these opposed electrodes to the surface of the main electrode E so concentrates the field that substantially all the lines of force of each field are collected immediately between the main electrode and the opposed electrode. Suitable screens or dividers D, D D are provided to maintain and preserve the separation of successively selected ingredients of the material M by the successive action of the electrodes E, E E, E. If the proportions of the apparatus are such that the electrodes E, E", etc. have to be placed in comparatively close proximity to each other, the screens D, D etc., may be made of metal and electrically connected with the electrode E, so as to act as electrical screens to prevent interference of one local field with another.

The exciting apparatus peculiar to each of the electrodes (with the exception in the specific instance here shown of the electrode E is the same in substance as that shown and described in the Pickard patent No. 796,012. The exciting devices for the several electrodes are arranged in parallel between the lead wires 1 and 2 of the common generator- Gwhich is conventionally shown herein as an alternating current generator. The primary coils P, P P, P* are arranged in parallel,

' and the secondary transformer coils S, S S S have their terminals 3 connected .with the main eiectrode E, and their terminals 4 connected through the modiratus intimately associated with the electrodes E on the one hand and E, E EHE on the other will be found in the Wynne and Pickard patents above mentioned, and I will, therefore, merely enumerate the parts without extended explanation. r, r r 1* are resistances in the secondary circuit interposed for the purpose of damping or suppressing oscillatory effects which might be produced by reason of the coaction of the capacities of the condensers'K, K K? and the inductances represented by the secondary coils S, S. I,'I l are the spark gaps which close the secondary circuit when the potential therein reaches apoint at or near the crests of the potential waves.

which, as hereinabove stated, should be all characterized by the same sign. R R It are non-inductive resistances interposed to short-circuit the electrode E on the one hand and electrodes E, E E on the other. I have indicated the provision of means for adjusting the total resistance of the resistances R, R R in the shape of movable contact points 0, l", C. I

By varying or adjusting the ohmic resistance of the non-inductive resistances R, R R the duration of' the potential accession and field produced thereby at the electrodes can be regulated, the higherthe shortcircuiting resistance thelonger will-the electrostatic field at the electrodes be maintained. a: conventionally indicates a rectifier. 5 and 6, Fig.' 3, represents with substantial fidelity the curve of potential accession at the electrodes when the short-circuiting resistances as R are comparatively low. Fig. 4 represents the curve say for the electrodes E, E the resistance B being greater than that of R, and Fig. 5 illustrates the still further protraction of charge at the electrodes due to a still further increase in the ohmic resistance in, say, the resistance R. I have shown in Fig. 2 the electrode E is connected Thus referring to Figs. 3, 4-,

directly to the secondary S without any intermediate apparatus. This mode of connection will create a field at the electrode E whereof the variations in potential are fairly represented by the curve shown in Fig. 6, and such a condition,when the potentials employed are high, is, in substance and effect, the same as would be characteristic of a continuous application of potential without variation in sign.

Let us su pposc that the material M contains valuable ingredients a, b and c and a miscellaneous gangue d, and that, according to the definition of the term set forth and explained in the patent to Philip Henry Wynne above mentioned, these several substances differ one from another in conductivity, material 0 having the highest conductivity and materials 'b, c and d inferior conductivities in gradation. In order to charge and repel particles of material a, an accession of potential of the utmost brevity is sufficient. Accessions of a duration sufiicient to repel from the electrode E the particles of material a will be too brief to effect the repulsion of particles belonging to classes b, c or (I, while these latter classes of material are attracted to the electrode E by means of the local charges deposited thereon by the ionized gaseous jet. Consequently, as they pass between the electrodes E and E, the particles of material a will be affected by and respond to potential accessions such as are represented by the very sharp wave form of Fig. 3, and will leave the large electrode E, fall upon the screen or divider D and becollected in a suitable-receptacle. The effeet of the recurrent brief potential accessions at the electrode E is not only to repel the particles which under the time-conditions of charge there maintained are perfect conductors, but also to cause the coherence of the other particles to the electrode E in the manner which I have explained hereinabove, that is to say, the jets of ionized airlocalized in the field between the electrodes E and E cause local charges to lodge, so to speak, on the portions of the inferior conductors which are remote from and not in contact with the surface of the electrode E. As these particles are carried by the electrode E, classes b, c and (l, mingled together arrive at the field generated between the electrodes E and E The potential of this field is characterized by accessions of longer duration than those of the field at the electrode E such, for instance, as represented by the curve in Fig. 4, and potential accessions of this duration are adjusted so that they are sufficiently protracted to cause particles of class b to become charged similarly to the electrode E, and be repelled, thelocal charges due to the ionized gaseous jet being overc'ome by the opposed potential of the electrode E, and the .particles of this class are collected by the screen or divider D The material now consisting only of classes 0 and d, continues clinging to the electrode E until electrode E isreached when the longer enduring potential accessions, as represented by the curve of s Fig. 5, charge the particles of class 0 by conductive contact'with the electrode E and cause them to be repelledirom the electrode E. When the residuum material d reaches the electrode E it is desirable to clean the electrode as thoroughly as possible of all adhering material, and this is done by applying a substantially continuous charge to the electrode E which 'by reason of the high potential employed charges all of the particles similarly to the electrode E, and as it were, strips them from the electrode by repulsion. There will be, however, a very fine dust in some instances which is not removed by the cleansing action of the protracted field between the electrode E and electrode E. This, however, yields to the action of the mechanical brush of felt scraper B and silch fine particles as d are to all practical intents and purposes thoroughly removed by the action-of sucha brush. Atall events the final residue of fine particles d may be made so insignificant that its absolutely complete removal is a matter of indifference.

Fig. 7 is a conventional illustration on a.large scale of the combined'and' cot'iperative action of the Wynne principle of auto-repulsion by brief potential accessions and of the underlying principle of my method of local charges deposited by the conveyance of ions upon the exposed surfaces of inferior conductors. In this figure I have illustrated-those particles which are, under the conditions imposed, sufliciently good conductors to receive a charge from the electrode E by reason of their effective conductive contact therewith, by circles and these particles which under these conditions behave'as non-conductors, by squares, and have shown these' altei nately arranged upon the surface of the el'e'f ode Er As the effect of the glass envelop aroundthe, electrode E is to concentrate the field as though the 'wire'E were at the .dotted line-position marked EC-l the fieldis localized between the virtual. position of the electrode E! and the electrode E, and is so concentrated'that at all other regionsupon the electrode E substantially nocharg e resides. As the' con-' ductorsand non-conductors pass in successidn into this concentrated field,-th'e conductors represented by the circles r'espond'to the dominant'infiuence of the ele cl, :trod'e Eand receive its charge by immediate conduc tion, and, as explained in the Wynne patent aforesaid,

become electrically one with the electrode E, and as ,they are mechanically separate. from that electrode,

. -40: are immediatelyrepelled from its surface. The degree I of concentration of fieldis susceptible of wide varia- 4 tions to meetchanging conditions of practice. .The inferiorconductors on the other hand are slow to receive a charge by conduction' from the electrode E so that the ions conveyed by the gaseous jet in the field are, as

it were, deposited upon the surfaces" of the non-conducting particles which face toward the electrode E.

In 7 I have indicated this locally deposited charge by a'spot or coating onthe outer faces of the squarepar tides. Iffor illustration, we assume that the elec-- trode E carries a positive and the electrode E a negative charge, these locally. deposited charges on the poorly-conducting particles will be negative, and therefore, whether they rest for the time being upon a positively charged area of the electrode E, or passout of the field, so that they rest upon asubstantially neutral surface, the potential of these poorly-conducting par-' ticles' is different from that of the surface on which they rest, and consequently they cling thereto; their adherence-is pronounced and their contact intimate because I in practice the particles themselves are very small and the linear distance between the locally resident negative charge and the surface of the electrode E is very small, resulting in an instant and effective attraction.

6-5 In Fig. 8 there is illustrated on a large scale similarly to Fig. 7 that phase of my improved process which is manifest at the field produced by theelectrode E in from the electrode, only the poorestconductors are conveyed into the field between the electrode E and the electrode E. Here the duration of the potential accessions is protracted so that to all intents and purposes -it is continuous, and the particles, which have theretofore behaved as though absolutely nonconductors, are subjected to the field -for a long enough time-to enable the charge on the electrode E to be communicated by conductionto the particles. When these particles have become enveloped, so to speak, by the charge peculiar to the electrode E, the 10- Here, assuming that all of the particles whichpan be selected for repulsion by the operation of theprinciple of the Wynne process, have been removed cally deposited charges on the particles themselves circles. Assuming that the electrode E carries aplus charge and the electrode E a minus charge, the poorly conductive particles shown as square come into the field with a locally deposited negative charge on their outer faces and though the" stream or jet of ionized gas in the concentrated field tends to maintain or increase the-localized charge,- the intimate contact between these particles and the electrode enables the protracted charge upon the latter to overcome the feebler influence of the ionized gaseous jet and to bring each one of 'the particl'esit'o a condition ofpositive charge,

and the instant this is accomplished the positively charged particle leaves the ele'ctroderE. I have shown some of the square particles as completely enveloped by a circle and other particles carrying a local negative charge'on one side and the growing positivecharge on theop'posite side, .thereby illustrating the progressive.

over-balance of'the negative ions by positive ions,

What I claim and desire to-secure by Letters Patent .is: I

1. The process of differentiating the components: of

mixedsolid, material which consists in introducing the mixture to an electrostatic field, there subje'ctiug'th'e mixture to an ionized gaseous jt, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior-conductors locally charged, andthereafter separately' collectingthe diverse components.

2. The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field} there subjecting" the lecting the'diverse components.

3. The process of differentiating thecomp'onents 6':

mixture to an ionized gaseous jet for a timelnsuificient to more than locally charge inferior conductors, mean-i while depriving the superior conductors in the'mlxture of the charge received from the jet, leaving the inferior f conductors locally charged, and thereafter separately ,coi-

mixed solid material which consists "in introducing the mixture to ,an electrostatic field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the mixture t0- an' intermittent ionized gaseous jet, meanwhile depriving the superior conductors in the mixture'of thecharge received from the jet, 'leaving the inferior conductors locally charged, and thereafter separately collecting the diverse components.

i. The process of separating the components of mixed solid material which consists in placing the mixture on a conductive electrode, there subjecting the mixture to an.

ionized gaseous jet from an opposed electrode, depriving the superior conductors of the charge received from the jet by conductive contact with the conductive electrode, leaving the inferior conductors locally charged, and thereafter causing the superior conductors to leave the conductive electrode.

The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors.

6. The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixtureto an ionized gaseous jet for a time insufiicient to more than locally charge inferior conductors, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors.

7. The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the mixture to an intermittent ionized gaseous jet, meanwhile depriving the superior conductors in the mixture of the charge re ceived from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors.

8. The process of differentiating the components of .mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet, meanwhile depriving the superior conductors in the mixture of the charge received from the jet,leaving the inferior conductors locally charged, then removing the superior conductors from'the locally charged inferior conductors, and thereafter correcting the local charge of the inferior conductors by subjecting them to '-the influence of a second electrostatic field.

9. The process .of diiferentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet for a time insuificient to more than locally charge inferior conductors, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charggi inferior conductors, and thereafter correcting the local chargeof the inferior conductors by subjecting them to the influence of a second electrostatic field.

10..The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the mixture to an intermittent ionized gaseous jet, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors, and thereafter correcting the local charge of the inferior conductors by subjecting them to the influence of a second electrostatic field.

solid material which consists in placing the mixture on a conductive electrode, there subjecting the mixtureto an ionized gaseous jet from an opposed electrode, depriving the superior conductors of the charge received from the 11. The process of separating the components of mixed jet by conductive contact with the conductive electrode.

leaving the inferior conductors locally charged, thereafter causing the superior conductors' to leave the conductive electrode, and finally correcting the local charge of the inferior conductors by subjecting them to the influence of an electrostatic field.

12. The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet. meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors, and finally subjecting the inferior conductors to the influence of an electrostatic field for a time sufiiclent to charge them fully.

13. The process of diiferentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet for a time insufiicient to more than locally charge inferior conductors, meanwhile depriving the 'superior conductors in the mixture of the charge received from the jet, leaving the inferior conductors locally charged, then removing the superior conductors from the locally charged inferior conductors, and finally subjecting the inferior conductors to the influence of an electrostatic field for a time sufiicient to charge them fully.

14. The process of differentiating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the mixture t an intermittent ionized gaseous jet, meanwhile depriving the superior conductors in the mixture of the charge received from the jet, leaving the inferior conddctors locally charged, then removing the superior conductors from the locally charged inferior conductors, and finally subjecting the inferior conductors to the .influence of an electrostatic field for a time sufiicient to charge them fully.

15. The process of separating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the material to an ionized gaseous jet, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving the inferior conductors locally charged by ,the jet.

16. The process of separating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potentialaccessions separated by intervals of substantially no potential, there subjecting the material to an ionized gaseous jet, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving the inferior conductors locally charged by the jet.

17. The process of separating the components of, mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet for a time insufiiclent to more than locally charge inferior conductors, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving the inferior conductors locally charged by the jet.

18. The process of separating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potential accessions separated by intervals of substantially no poan ionized gaseous jet, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving the inferior conductors locally charged by the jet, and thereafter correcting the local charge of the inferior conductors by subjecting them to the influence of a second electrostatic field.

20. The process of separating the components of mixed solid material which consists in introducing the mixture to an electrostatic field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the material to an ionized gaseous jet, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conduc-- tors from the mixture, leaving the inferior conductors locally charged by the jet, and thereafter correcting the local charge of the inferior conductors by subjecting them to the influence of a second electrostatic field.

21. The process of separating the components of mixed solid material which consists in introducing the mixture to an electrostatic field, there subjecting the mixture to an ionized gaseous jet for a time insufiicient to more than locally charge inferior conductors, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving the inferior conductors locally charged by the jet, and thereafter correcting the local charge of the inferior conductors by subjecting them to the influence of a second electrostatic field.

22. The process of separating the components of mixed solid material which consists in introducing the mixture to an elez-trostatic'field characterized by brief potential accessions separated by intervals of substantially no potential, there subjecting the mixture to an intermittent ionized gaseous jet, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixture, leaving-the inferior'conductors locally charged by the jet, and thereafter correcting the local charge of the inferior conductors by subjecting them to the influence of a second ele trostatic field.

23. The process of separating the components of mixed solid material which consists in placing the material on a conductive electrode, there subjecting the material to an ionized gaseous jet from an opposed electrode, conducting a repelling charge to the superior conductors in the mixture, thereby overcoming the charge received from the jet and removing the superior conductors from the mixtures. leaving the inferior conductors locally charged by the jet, and finally correcting the'local charge of the inferior conductors by subjecting them'to the influence of an electrostatic field.

24. Theprocess of separating the components of mixed solid material, which consists in introducing the mixture to an electrostatic field, there subjecting themateria'l to an ionized gaseous jet, conducting a repelling charge to the superior conductors of the mixture, thereby overcoming the charge received from the jetand removing the superior'conductors from the mixture,- leaving the inferior.

conductors locally charged by the jet, and finally subjecting the inferior conductors to the influence of an electrostatic field for a time suflicient to charge them fully by direct conduction.

Signed by me at Boston, Suflt'olk county, Massachusetts this seventeenth day of December 1906.

-HENRY AZOR WENTWORTH'.

Witnesses:

QDIN ROBERTS, J osnrn '1. BRENNAN.

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