US1744967A - Art of separating and apparatus therefor - Google Patents

Description

Jan. 28, 1930. F. R. JOHNSON 1,744,967

ART OF SEPARATING ANDAPPARATUS THEREFOR Filed Aug 25, 1927 2 Sheets-Shee 1 I I I I I I I O I 1' 15 i 5 13 F l I V 1 U6 77 to? /7 I .Fedfi. Joiwwon 1-9 fl'l%07 71ey6' Jan. 28, 1930. F. R. JOHNSON 1,744,967

ART OF SEPARATING AND APPARATUS THEREFOR Filed Aug. 25, 192"! 2 Sheets-Sheet 2 Patented 28 1930 UNITED STATES FRED ROTHWELL OHNSON, OF HAMBURG, NEW YORK ART OF SEPARAT1NG AND APPARATUS THEREFOR Application filed August 25, 1927. Serial No. 215,468.

This invention relates to improvements in ,the art of- Separation of unlike particles found mixed in a mass. More particularly the invention provides a 5 method, and apparatus for practicing it, which will probably be found applicable most frequently in cases where the particles to be separated differ in shape, some for example, vbeing small or flat, while others to be separated from them are larger or of a shape more adapted forrolling. Ordinarily this will'attend a difference of material, as for separating garnets from mica in a comminuted mass containing both. But theutility isnot limited to that, but may be applied for separating difi'eren't shapes of the same,

material, assfor separating the round particles from the slivers in a ground mass of artificial abrasives. And it is applicable also in cases where the distinction between particles to be separated may not lie in their shapes, so much as in their respective abilities to acquire a charge of static electricity.

The method by which the separating is accomplished subjects all of the particles to a test by'a continuous process in the course of which each article is deposited on an inclined surface set at a suitable angle so that, for example, the fiattish particles will 'not 39 slide down it while the rounder bodies will do so. In the instance mentioned the flat particles hold their position by friction; and preferably .they are continuously removed from the place of deposit as by providing that the said incline on which they are deposited is a conveyor belt moving upward which carries them up and discharges them from its top. The power of the belt, to hold the smaller or flatter particles and not the larger or rounder ones, may be enhanced by making the belt corrugated; and the force offriction, or the force akin to friction, with which the belt holds certain of the particles may be r amplified by charging all of the particles pre- 0 liminarily, or subjecting them to an equal opportunity of becoming charged, with electricity, and providing an electrode of opposite sign close under the belt at the place where the are deposited thereon, so that those whic are equally charged and are lighter, or have because of their shape or theirv material acquired stronger charges than others, or carry their charges closer to the belt, are held more strongly on the belt. A further separation may be effected, as a part of the same continuous process, among those particles which have been drawn off from the place of deposit by gravity and have rolled down the belt. An electrode charged with static electricity of suitable polarity with reference to the polarity with which the falling particles are charged may be set near the course through which they are falling so as to def flect the trajectory of those which are the more strongly charged, so that they fall in a place where they are by themselves, apart from the place Where the less strongly charged particles fall. For one example of a practical application of this the process may be considered as it may be applied for-the 7o purification of crushed kauri gum. All of y the comminuted materials being fed in a thin stream over a plate having a strong negative electro-static charge, each particle thereby picks-up some negative charge, so that when the stream falls upon abelt moving upward at an angle, close above a strongly charged positive electrode, the sticks, leaves and small dirt, lying fiat upon the belt and further held by the electric attraction, are carried upward by the belt, while the gum and mud balls roll down the incline of the belt. But, as they fall from its bottom and pass near another electrode positively charged, thesefalling particles are difi'erently affected, the mud alls being drawn toward the electrostatic positive pole, while the gum (which has less good conducting power and therefore has picked up on the surface less of negative electricity from its passage over the negatively charged plate) is not drawn so much toward 'the positive electrode and therefore falls more nearly in its. natural trajectory. If the percentage of impu'rities thus separated from the gum is not suflicient, or if too much gum is carried away with either of the separated classes, the product may becarried to a higher degree of perfection by passing it immediately and automatically through apparatus arranged in tandem to receive the productvof' 10 either of the classes and adjusted to the pari represents the apparatus of the invent-ion;

ticular needs of the material which it is to handle. It will be observed that the method does not require in all instances that the inclined surface be one which is moving upward as a conveyor, for with certain materials a distinction may exist as to the places where the two classes of material fall from the incline; as :Where all materials fall but some is held back by friction as it slides down so as to fall more nearly vertical, While other material of rounder shape Bounding down the incline falls further away.

The invention may be applied in various Ways", one of which is illustrated and described herein with apparatus. for practicing it, as an example, to which however the invention is not limited. It is intended that the patent shall cover, by suit'able expression in the appended claims, whatever features of patentable novelty exist in the invention disclosed.

In'the accompanying drawings:

Figure 1 is an elevation of apparatus, in section, in which the art of the invention is being racticed and is embodied, the appa ratus illustrated in Figure 1 being a detail on a larger scale of part of that shown in Figures 2 and 3; and

Figure 2 is a side elevationof apparatus for practicing the invention as a process and and Figure 3 is an elevation of the same in section on the line 33 of Figure 2.

Referring to the drawings, 10 indicates a frame holding various instruments in vertlcal succession from the hopper 12 downward, for vdealing with all or part of the ma.-

'under the belt.

terial a b c seen in the hopper 12, which has an open bottom for delivery of the material at a rate determined by the setting of the screw 13, by which one side wall 14 of the hopper can be raised a little above the roll 16, which, turning at a suitable rate, contin uously carries material out from the bottom of hopper 12 under the gate 14, so that it falls upon an apron 17 which is of metal steep'enough for the material to slide down by gravity and is strongly charged with static electricity of a certain polarity, for

example, negative. The bottom edge of this' blade is serrated, preferably having points 18,- seen in Figure 3, and can be ad usted to a suitable elevation and there held by the clamp 19, Fig. 4, so that its points are close above the surface of the conveyor belt 20,:

leaving room for material on the belt to pass under them, and are also near the elec-.

trode 30 of oppositeolarity which is close This It 20 may preferably be of rubber, which is a convenient flexible insulating substance, and for many materials may preferably be corrugated so as to make it more diflicult for parts of the mass to slide down the belt while not preventing larger or differently shaped articles from sliding or rolling down it. This belt is represented as being carried on guide rolls 22, 24, by which it'is driven so that its upper surface moves upward, and is held taut to, a suitable ment of the bearing 25 of the roll 24, by the degree, this latter being affected by adjustscrew 27 and by the clamp 26. The'latter 32 crossing between two arms 34, one at each a edge of the machine, which areadjustable and holdable by the pin and slot clamping arrangement 36, the tube itself being held by screws 38 fastened to the insulating block 32. Another'electrode, of positive polarity, is represented at 40 where it is set near the trajectory of articles which fall from the bottom of the belt. The connection to these various electrodes may be made in any ordinary or suitable manner, and the static charge may be of any suitable voltage. It has been found that from 5000 to 35,000 volts as produced by adisk static machine is suitable, although it should not be understood that the practice of the invention is limited to this range. The lower edge of the apron 17 may with advantage be adjusted to be within a half inch or less of the positive electrode 30 which is beyond the belt 20 from it, with the belt 20 and material thereon intervening. The dimensions and the speed of the belt may vary according to circumstances,

one suitable dimension for example being anywhere between one foot and four feet wide for the belt, moving at a speed of ten to fift feet per minute.

In t e operation of this apparatus, practicing the process of the invention, the mixed I a material a b 0 passes out from the hopper 12 in a continuous. thin. stream, determined by the setting of the gate'14, passing out with the rotation of the roll 16, which may conveniently be merely a length of three inch shafting or other material suitably mounted in bearings at its end; and this thin stream of the mixed material flows down over the apron 17 and: slides off the points 18, with each particle be-.

the small particles to roll down, even t'fiiiugh they be round, and these are held thus by a force which is akin to friction so far as the purposes of the present invention'are concerned, so that in the claims the word friction is used broadly as typifying pure friction and also forces akin to friction, among which may also be classified the holding tightly upon the belt, with the effect of preventing sliding, which results from the action of the'electrostatic forces. Material 0 which is carried upon the belt would be the sticks and leaves and fine dirt in the kauri gum illustration cited, which had acquired a charge of negative electricity and so is marked 0, and which is delivered by the conveyor upon a chute 44, to

- be gathered in some convenient place as tail in The particles (1' and b which gravity 'pu ls down on the belt are discharged as indicated in Fi re 1 and fall freely from the bottom of the elt. They may, however, be separated automatically into those which being rounder are travelling down the incline with greater velocity than the rest and thus fall further from the belt, indicated at b, and those which fall more straight indicated at a.

In the illustration mentioned it is assumed that the mud balls would be the more round and would fall farther from the belt, and they would constitute middlings I), while the purest gum particles a would fall more directly. Figure 1 illustrates also the use of another positive electrode 40 which being placed near the falling stream pulls more strongly on the mud balls than on the gum balls because they have been capable of picking up a large charge of electricity in passing over the apron 17, and this pull accentuates the separation between the two kinds (1 and b, so that a deflector 42 can guide each kind to a place by itself. Figure 2 illustrates how the process can be repeated in the same apparatus for the further separation of one of these separated streams, the apparatus being set in this instance to operate upon a stream falling in the position of the stream a of Figure 1,

which the deflector board 42 throws upon a lower apron 17 passing it through apparatus similar to that above it, already described, and arranged to deposite its tailings, middlings and concentrate respectively in the containers 45, 43 and 41;

7 Thus theconjoint application of the forces of' gravity and of friction to the particles of the mixed mass; when arranged so that they are free to respond independently according to their several characters, results in gravity controlling theultimate location'of some of them and friction the ultimate location of others, these two locations being at 'cable distances 2. art for effecting the esired separation of di erent classes of particles that were in the mixed mass.

The desired polarity of apron 17 and opposite polarity of the insulated electrodes 30 and racti- 'asre 17 increase the effect of electrode 30 to hold fiat particles on the belt, as the points create a spray which repels while a more flat surface .will attract. ,The rubber belt is an insulator 'which tends to prevent the electricity from arcing across between the charged electrodes. Other suitable insulating material such as leather or canvas can be used.

I claim as my invention r 1. A process for separation of diverse classes of particles in a mass of freely movable particles wherein the classes are mixed, comprising the conjoint application to each particle of the force of gravity, a force exerted by an underlying solid body obstructing the direct pull of gravity, an electric force, and a frictional pull; wherein'the force of gravity is applied to the particle downward; the obstructing force is applied to obstruct a direct downward while permitting a laterally downward movement of the particle; the fricpositely lateral, friction being-generated by v the said downward pull of gravity; and the electric force is applied to increase the pressure and'friction of the particle against the said underlying body, whereupon the particle moves laterally downward or upward according to the resultant of said forces actinguonit.

2. eparatingapparatus comprismg a conveyor having a material-engaging surface set to move upward at an incline; means for ex posing the mixed material to become charged with electricity; means for spreading the charged material on said surface; andan electrode, ofpolarity opposite to that of the.

material, close under the said surface and arranged to force each particle of said mate-' rial toward that surface; the said incline being slight enough for the conveyor to held against gravity one class of particles Wh1Cll is in the mixed material and being too great for the conveyor to hold against gravity the other class therein. I

3. Separating apparatus 'comprlsing a hopper for material having meansfor the gradual discharge thereof; an electrically charged apron over which the discharged material flows and whereon 1t is'exposed to becoming charged with electricity; 'a conveyer upon which the apron delivers it-,-'set to move upward at an incline; and electrical means for drawing the chargedumaterial against the conveyer with increased frictlon thereon, whereby" the distinction between partlcles of different classes in the material-is enhanced ards their respective adhesion to or falling a ongthe inclined conveyer.

'4. Separating apparatus comprising a hopper for mixed material with means for the gradual discharge of material from the hopper; an apron over which the discharged material flows; a conveyer to which the apron 5 discharges the material, having a materialengaging surface set to move upward at an incline; an electrode set under the conveyer close to the place where material is deposited thereon; the said apron being charged electrically of opposite polarity and having at its delivery edge points toward said electrode and at a short distance therefrom; whereby the electrical action draws particles more strongly toward the surface of said conveyer, e

with friction enhanced, distinctively according to the class of each particle in the mixed material; particles of one class being held against gravity on the conveyer, while the urge of gravity .is suflicient to overcome the friction of the other class on the conveyer.

5. Apparatus for separating comminuted material into classes comprising an inclined surface on which one class of the material I can be moved downward by gravity and on which the tendency of gravity to draw the other class of material downward is re- 7 strained to a greater degree than in the case of the first material by the engagement of the restrained material with the surface of the incline, yet not sufficiently to prevent the second class also from moving'down the incline; means for charging the material electrically before it leaves the incline; and an electrode set near the trajectory of one of said classes of material leaving the incline whereby its course is deflected to increase the separation between the two classes of falling material. v

6. A separator for diverse classes of parti- 4o cles in mixed material comprising a hopper for holding the mixed material having at its bottom a roll for holding the material therein and for feedin it thence under a bottom of a side wall 0 the hopper; an electrically charged apron upon which said roll delivers the material; a belt conveyer set to move upward at an incline, receiving the'discharge from the apron; the said r incline being such that one class of the mixed material is held frictionally thereon and moves upward therewith while another class is drawn by gravity more powerfully than it is held by friction "and moves down the upward moving belt; and an electrode of opposite polarity from the apron and the material, set under the belt where the material is received from the apron and adapted to draw particles of the mixed material more tightly against the surface of the conveyer, whereby distinctions as to fric; 6 tional adhesion or non-adhesion of different classes of particles to the belt are increased. Signed alt-Hamburg, Eriecounty, N; Y., this 13th day of August; 1927.

u FBEDABOTHWELL JOHNSON.

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