US1840267A

US1840267A - Process of separating materials

Info

Publication number: US1840267A
Application number: US291224A
Authority: US
Inventors: Tschudy Frederick
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-07-09
Filing date: 1928-07-09
Publication date: 1932-01-05
Anticipated expiration: 1949-01-05

Description

Jan. 5 1932. F. TSCHUDY I 1,840,267

PROCESS OF SEPARATING MATERIALS Filed July 9, 1928 6 Sheets-Sheet 1 v OZ Fig. L.

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PROCESS OF SEPARATING MATERIALS Filed July 9, 1928 6 Sheets-Sheet 3 sin/7' III :5 a at (O I Q 3mm E1) I FREDEmcK TscHuDY (A Jan. 5, 1932. F. TSCHUDY 1,840,267

PROCESS OF SEPARATING MATERIALS Filed July 9. 1928 s Sheets-Sheet 4 msmxm 0 IIIIIHIIIIIIIJIIIIII I gwuentoo A FREDERmK TSCHUDY Jan. 5, 1932. TSCHUDY 1,840,267

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Fig.

Jan. 5, 1932. F, TSCHUDY 1,840,267

PROCESS OF SEPARATING MATERIALS Filed July 9, 1928 6 Sheets-Sheet 6 1mm? FREoERmK TscHunY gnucul'ot I Patented Jan. 5,.1932

UNITED STATES- FREDERICK 'ISCHUDY, OF ENSLEY, ALABAMA PROCESS OF SEPARATING MATERIALS Application filed 311179, 1928. Serial No. 291,224.

This invention relates to a flotation process for the separation of materials of different specific gravities. My invention, while of general application is partially adapted to the treatment of coal. v I

It has heretofore been proposed to treat materials by the flotation process, using either involuntary ionization or ionization produced by chemical reaction. For example, it-has been proposed to add electrolytes to the flotation bath to aid in the process. As far as I am aware, in all of these ionization processes the ionization in uncontrollable either as to quantity or potency.

flotation bath a gaseous medium highly or strongly charged with electrical ions of either polarity depending upon the character of the material being treated and of a strength or potency as may be re uired by the material 7 being treated. Broad y stated, the gaseous medium may be charged prior to its entry into the flotation bath by any means which produce the desired ionization effect. The gaseous medium may comprise a single gas or a mixture of gases.

Another feature of my invention is the presence of a control over the adually increasing static effect on the otation bath which is a direct result of the introduction of a gaseous medium carrying an intense electrical charge or, stated differently, highly ionized by virtue of the electrical charge. In one form of my invention the control includes a. the provision of a condensing surface, suitfibl located and distributed in the flotation My invention also includes the application of a stabilizer to the flotation bath and in its 4 preferred form the stabilizer has substantially the same physical, including electrical, and chemical characteristics of the aggregate being treated, adapted to be included in .the finishedproduct of the process.

In the preferred form of the invention it isdesirable' to maintain in the bath two or more zones of turbulence as will more specifically be pointed out hereinafter.

Another feature of my invention is the control of the relationship between the amount According to my invention, I pass into the ore is usually finely disinte rated and even of liquid present in the bath-and the amount of aggregate. Stated differently, in general the liquidity of the bath must be in due relationship to the amount of aggregate, as expressed in terms of volume. Stated broadly, the relationship must be such as to permit the. V proper distribution of the ionized air bubbles, and simultaneously allow a quick separation of the valuable material from the gangue and an unhindered recovery of the former.

In the preferred form of my invention I contemplate the creation of a zone of fluctuation at or near the surface of the bath, the fluctuation being controllable as to depth of reaction and time of repetition.

While as has been stated, my invention is broadly applicable to various materials, each type of material requires the application of the broad underlying principles of the invention in a specific manner. For example,

the coarser ores, usually sub ected to a flotation treatment, approach the stage of pulverization. --It necessarily follows that the finely divided particles act differently in a flotation bath than an aggregate com ound if substantially larger granular particles, as

is well illustrated by a material such as coal.

It may be pointed out that ores may be disintegrated to a fine state of division, treated and recovered in a suitable. (:(Tmmercial state. However, in the case of coal, fine pulverization is distinctly undesirable as beyond 100 mesh it becomes explosive, and cannot be transported as coal but requires speg5 cial handling at high freight rates. This, in itself, indicates that the preferred state of the coal to be subjected to a flotation treatment is that of granules as large as possible and consistent with other limitations inherent in the flotation process. Further, in the case of ores, usually the gangue constitutes the major portion of the material "while, in coal, the gangue constituent is relatively small.

It may be further pointed out that granular coal possesses a potential electrical field of reaction, many times greater than ore finely ground and high in gangue. It is also desired to indicate that in the case of bitumi- 100 nous coals capable ofcoking, a finely divided state is not suitable as in this form the material is not satisfactory for the production of industrial coke. Hence, in this ar- 5 ticular case, it is necessary to apply the o'tation process to a granular material. However, as indicated hereafter, my broad process may be applied to the recovery of coal dust. Stated broadly, the dominant feature of my invention is the separation of materials of different specific gravities by the flotation process by subjecting-the materials to treatment with a gaseous medium highly or strongly and controllably charged with electrical ions and preferably, the gaseous me dium is charged by passing over the corona discharge. In its more specific form the rocessincludes the passage of a stabilizer 1nto the flotation bath. Ialso propose to control the amount o'fliquid present in the bath and the amount of material being treated. The process also includes in its preferred form the creation of a zone of fluctuation at or near the surface of the bath. I also propose to prevent the accumulation of a static charge in the bath and remove the condensed charge from the bath. The invention is more particularly pointed out in the following specification and the scope thereof is indicated in the annexed claims. While my invention is not limited thereto, it is particularly suitable for the treatment, and recovery of granular material.

My invention is particularl eflicacious in the treatment of coal, and t erefore, for the purpose of illustration, the invention will be described in connection therewith. It is, however, to be distinctly understood that the'broad underlying principles of the invention are applicable to materials generally subjected to the flotation treatment including minerals, ores andshales.

In order that my invention may be understood, it will be described in connection with the accompanying drawings, in which:

Figure 1 is a plan view of a-complete cell unit; I

Figure 2 is a transverse section of the cell taken on line 2-2 ofFigure 1;

Figure 3 is a longitudinal section taken on line 33 of Figures 1 and 2;

Figure 4 is'a longitudinal section'taken I on line 4-4 of'Figure 2;

Figure 5 is a transverse section on line 55 of Figures 1 and 4; and

Figure 6 is a diagrammatic representation of the apparatus for producing ionization of the gaseous medium.

Referrin to Figures 1 and 2, the material which is su jected to the flotation process is introduced through a hopper 1 and passes over a conveyor 2, preferably of helical type,

- into a series of discharge spouts 3, as plainly indicated on Figure 4; The conveyor 2 1s mounted on a conveyor shaft 5. From the discharge spouts 3 the material drops onto a distributing plate 4 which also functions as a condensing medium or surface. The cell is provided with a stabilizer pipe 6 for the introduction of a stabilizing material into the flotation bath. As indicated on Figure 5, the stabilizer pipe 6 is provided with an inlet 6a. In operative connection with the stabilizer pipe 6 are nozzles 7- acting to distribute the stabilizer into the bath. A water pipe 8 is provided for supplying make-up water necessary to maintain the specific relation between the material being treated and the water comprising the flotation bath. As indicated in Figure 5, the pipe 8 is provided with an inlet 8a. The pipe 8 is also provided with a series of nozzles 10 for distributing the make-up water to the bath. The stabilizer nozzle 7 and the make-up water nozzles 10 function to create zones of turbulence as approximately indicated in Figure 2, by guide lines 8, s, t

cated in Figure 2 by guide lines a and u.

Stabilizer pipe 6 and-make-up water pipe 8 are insulated in any well known manner so as to prevent an uncontrollable electrical reaction. 'This insulation can be at any convenient point prior to the attachment of these pipes to the cell unit. The ionization pipe 9 is insulated the entire length from the ionizing apparatus to the cell and the pipe itself may be made of a non-metallic material such as bakelite, fiber, porcelain, etc., to prevent a condensation of the ionized air on the walls of the ionizing pipe. Stabilizer pipe 6, makeup water pipe 8, and ionization pipe 9 are adustable so they may be rotated to control th turbulence zones.

The numeral 12 indicates the cell as an entirety. 'The'cell is provided with end castings A and B, which function as hereinafter more particularly s ecified, to carry the rehorizontal direction toward the front 17 of the cell, the horizontal portion being indicated by the numeral 16. It will be noted that the members, 13, 14, 15, 16 and 17, are mounted at one end of the cell on the casting A and at the other end of the cell on the casting B,

zone of turbulence as approximately india as clearly shown in Figures 3 and 4. The walls of the cell unit are preferably made of wood which can be suitably treated, if desired, to increase its wearing propertles'. However, the cell walls may be made of concrete reinforced, if desired, or of metal, such as cast iron, wrought iron, steel, copper, zinc, aluminum, or may be of any material porcelain lined. The cell walls may also be made of any synthetic material, such as resinous compositions, for example bakelite and other synthetic resins now on the market. The cell bottoms may also be made of rubber or fiber impregnated with rubber or with latex. The cell walls may also be made of any com- 1 posite materials comprised of the above or their equivalents.

The cell 12 has a cover 18 which extends over the cell proper. This cover is made in sections and hinged at 19 and 20, as shown in Figure 2, thereby allowing access to the inside ofthe cell for the purpose of inspecting the mechanical equipment therein and ascertaining the condition of the .bath. The dominant idea in the construction of the cell proper is to provide a cell in which the flotation bath is kept from contact with atmophere.

The gangue resulting from treatment of the material introduced into the bath travels along the

members

14, 15 and 16 of the cell into a channel 21.. Disposed in this channel is a conveyor 22 preferably of the helical type. The conveyor 22 is mounted on a shaft 23 extending the entire length of the cell, as indicated in Figures 1 and'3. The conveyor shaft 23 is mounted in

bearings

24 and 25 disposed on the end castings B and A,

respectively. J On the end of the shaft 23 and in'end casting A, as shown in Figure 3, there is mounted a discharge drum 26. The discharge drum is keyed on the shaft 23 and rotates with the conveyor, the discharge drum and the conveyor shaft being driven by a sprocket 27, asshown in Figure 3.

The drum 26 is provided with a discharge I slot 28, preferably connecting once every revolution with a gangue discharge opening through spout 30, as shown in Figures 2 and 3. The drum 26 is positioned adjacent the discharge spout 30 into which the gangue passes once every revolution of the gangue discharge conveyor 22, the latter passing the gangue through the o ening 29. The discharge spout 30 is pre erablyintegral with the cylinder 31, which forms part of the'end casting A. It is to 'be noted that the drum 26 fits tightly against the cylinder 31. End bearing 25 may be anintegral part of the 3 cylinder head 32, which serves for the re- .moval of the drum and the keeping in place thereof.

The drum 26 is provided with an inwardly extending head 33 which encases the shaft 23 and prevents wear on the shaft. Opposite the discharge slot 28 of the drum 26 is a vent hole 34 leadin to a vent pipe 35. The vent hole 34 and t e vent pipe 35 serve to prevent the formation of a vacuum in the drum 26. The slot 28 is preferably located as shown but it is obvious that this slot may be turned at an angle to prolong the time and increase the quantity of the gangue discharge and also to regulate the zone of fluctuation near the top of the flotation bath. The rise and fall of the zone of fluctuation is regulated by a number of variable factors including the number of revolutions of the conveyor shaft 23, and the size and position of the discharge slot 28, and these variables may be regulated to control the zone of -fluctuation as necessary, and as dependent sitioned differently, it is desirable to posi tion it adjacent the front wall 17 of the cell 12 because it isdesired to avoid the rising of valuable material into the overflow.

Located inside of the cell 12 and adjacent the front wall 17 of the cell is a riser 36 provided with an inlet 37 and there is an outlet 38 in the wall of the end casting A. The entrance 37 to the riser 36 is preferably located adjacent the bottom of the cell and directly over gan ue conveyor 22 so as to permit water free rom valuable material to rise from opening 37 through the conduit 39 into the overflow outlet 38 and into the overflow sum 40. The overflow water level is indicate in general by the line DD, as shown more particularly in Figures 3 and 5. The size of the opening 38 and hence the bath level C-C- may be regulated by a regulating device 41 which comprises the adjustable weirplate 42 The overflow water accumulating in overflow box and defined by the overflow level DD passes from the box 40 into a conduit 43 provided with an outlet 44, as shown in Figure 5.

Referring to Figures 1 and 5, it will be noted that in case the spouts 3 should become clogged and thereby produce a binding of the material in the conveyor 2, there would be a likelihood that the conveyor shaft would break and therefore I have provided in the end casting A an auxiliary discharge. To take care of the tendency referred to, there is provided in the casting side wall 39 an outlet 45 opening into the auxiliary discharge box 46, this box being preferably integral with the end casting.

Means are provided for the removal of the finished product from the top of the flotationv bath 38. The means consist of a mechanical skimmer which is generally denoted by the numeral 47. The skimmer 47 comprises a series of travelling flights 48 which are mounted on chains 49 which rotate on front sprockets 50 and rear sprockets 51 which are mounted on

shafts

52 and 53, the former being driven and the latter the loose shaft. The

shafts

52 and 53 are mounted on bearings 54 in the end castings A and B of the cell. 1

It will be noted that the skimmer 47 is positioned at an angle so as to allow the flights 48 to dip in the flotation bath a suitable distance. In my experiments it has been found that it is satisfactory if the flights dip in the bath for a distance, varying between l and 3 inches. The flights 48 function to bring forward toward the surface CC of the flotation bath the granular material which has not reached the extreme top surface of the bath. As a direct result of inclining the skimmer 47 there is provided a substantially dry discharge. The valuable floated product passes out of the bathinto a discharge conveyor trough 55 which runs the full length of the cell unit. Positioned inside of the trough is a discharge conveyor 56, preferably of the helical type. The discharge conveyor is mounted on shaft 57 which is in turn mounted on bearings 58 in the end castings and B. The discharge conveyor 56 discharges into the spout or chute 59 which may be located at either end of the conveyor. All the rotating elements of the cell unit are driven from the discharge conveyor shaft 57 which in itself is driven directly from the source of power by means of chains 60 andv sprocket wheel 61.

In order to furnish power for conveyor 22 and drum 26, there is positioned on shaft 57 a sprocket wheel 62 which drives through chain 63 a sprocket wheel 64, mounted on shaft 23.

- In order to provide for the operation of the skimmer 47, there is positioned on the drive shaft 57 a sprocket wheel 65 which .drives sprocket wheel 66 through chain 67-, the

' mounte sprocket wheel 66 being mounted upon the shaft 52. The other end of the shaft 57 is positioned in bearings 58 and the shafl has thereon a sprocket wheel 68, as shown in Figure I by means of which chain 69 drives sprocket wheel 70 mounted on shaft 5, thereby completing the conveyor 2.

' Referring to Figure 2, it will be noted that 'the flotation oil may be introduced through the oil conduit 71 which is preferably located inside of the conveyor trough indicated in its entirety by the numeral 7 2. As in some cases the flotation oil may be introduced at other points in the cell 12, as will be more specifically indicated hereafter, the oil pipe 71 may be used to introduce water instead of oil. The pipe 71 will function as a water pipe when a relatively dry material is introduced; into the cell 12 in order that the spouts 3 may be kept clear. When the pipe 71 functions as a water feed pipe, as stated, the flotation oil may be introduced at other points in the cell.

Means are provided for adjusting and controlling the tlow of the material atthe rear of the cell 12. It will be noted that the gate 4 adjacent the member 14 of the cell is secured to hinge 73 which is also attached to the wall 74 of the conveyor trough 72. The gate 4 is adjustably positioned by means of a hand wheel 75 mounted on a screw 76. The screw 76 is anchored in a bearing 77, as shown in Figure 2. The lower end of the screw is pivotally connected at 78 to a link 7 9, which is pivotally connected to the gate 4, as at 80.

Referring to Figure 6, which diagrammatically represents an apparatus for producing ionization of the gaseous \medium employed in the process,

wires

81 and 82 are connected to a source of alternating current which may be 1, 2 or 3 phase, 25, 5'0, 60, or more cycles, and 110, 220, 360, 440, 660 or any other known commercial voltage. As the invention herein described requires the use of a high tension current the low voltage current is brought through wires 81 and 182 to a transformer 85',

where the low voltage current is stepped up by means of the transformer coils from the 2000 and 75000 and in some cases, the voltagemay be higher. As proper ionization of the gaseous medium used in the flotation process cannot be effectively produced by alternating current, the high tension current is rectified. The current passes by means of

wires

86 and 87 to a rectifier 88, diagrammatically indicated as a four hole kenotron. In my experiments I have used among others a 60 cycle current and when such a current issupplied'to the rectifier or kenotron, the latter must run synchronously with the cycles of the'alternating current,'hence', in this case, at a speed of 1800 revolutions per minute. vThe four pole rectifier 88 is provided with positive poles 89 and 90 and

negative poles

91 and 92. Through the action of the rectifier or kenotron the alternating current is changed to a direct current of that voltage originally produced 'in the transformer.

drive for the feed As, according to the present invention, a negative or positive ionization may be desired, means are provided for obtaining a negative or positive corona discharge. This may be accomplished by providin a suitable switch mechanism, one form of which I have diagrammatically illustrated. More specifitact 97. The

negative poles

91 and 92 are connected by means of a wire 98 to a contact 99 of a double switch 100, provided with a second contact 101 and a switch lever 102. Positive wire 93 is connected from contact 94 on switch 95 to contact 101 on switch 100. Negative wire 98 is connected through contact 99 to switch 100 and cross connected to contact 97 on switch 95. By closing switch lever 96 on to'contact 94 on switch 95, wire trated in Figure 6, is preferably in the shape of a tube of such a size that a bridging of the current from the ionization wire 103 to the walls of the chamber 105 cannot occur. According to my experiments, it has been found that utilizing 32000 volts, a six inch pipe is satisfactory as with three inches on either side of the ionization wire 103, no substantial bridging occurs.

The ionization chamber 105 may be made of either a conducting or non-conducting material as the voltage of the current may dictate. The ionization chamber 105 is provided with end flanges 106 and 107. The

flange 106 at the extreme end of theionization chamber 105 has mounted therein a suit able insulator 108. This insulator may be of porcelain or'a synthetic non-conducting 7 resinous material, such vas bakelite. Flange 107 is provided with a similar insulator 109. The corona-forming wire 103 is anchored. in the insulator 108 and passes through the insulator 109, which is sealed against the escape of air, as shown at 110.

Means are provided to prevent short circuiting of the high tension current through the shell of the ionization chamber 105 and this is accomplished by grounding the chamber or shell 105 in any conventional manner,

as illustrated by ground wire 111. The gaseous medium to be ionized, which has been compressed to the desired pressure, passes by b the way of inlet 112 through conduits 113 and 6 114 and inlet 115 into the ionization chamber 105. A valve 116 is provided, as will be hereinafter described. The gaseous medium introduced through inlet'115 passes along the ionization wire '103 which by the action of the current forms a corona giving ofi elece trical energy in the form of ions which are carried forward by the rapid movement of the aseous medium passlng throu h the cham er 105 to the outlet 117 then t rough conduit 118 to the feed pipe 119 connected to the cell ionization inlet 9a, which is in 'turn connected to the ionization conduit 9,

as shown in Figure 5.

According to the present invention, a substantially saturated gaseous medium may be introduced into the bath or the gaseous medium may be saturated as to its ionized condition, and means are provided to control the amount of ionization of the gaseous medium. When it is desired to introduce into the flotation bath a gaseous medium unsaturated as to ionization, a portion ofthe unionized air entering through the conduit 113 is by-passed through conduit 120 by partially closing valve 116 and opening valve 121. This allows unionized air to pass through valve 121 and meets ionized air issuing from conduit 118. In this manner the air passing through ionization feed pipe 119 will be unsaturated as to its ionization in accordance with the requirements of the material to be treated by the flotation process.

An example of my invention is as follows: Coal crushed to the required size is introduced through the hopper 1 onto the feed conveyor 2, preferably of the rotary type wherebyit is distributed along the

members

14 and 15 of the cell 12 and is discharged into a series of discharge spouts 3, onto the regulating gate 4, which also extend the entire length of the cell 12. The position of the regulating gate 4 is controlled by the screw and link arrangement to 80, inclusive, so

as to allow a regulated amount of granular material to flow along the downwardly curved bottom wall '15 of the cell, the latter, when the process is started, having present therein a suitable amount of water, up to the level CC. A stabilizing fluid termed herein the stabilizer, under suitable pressure, is then introduced through the stabilizer pipe 6, and passes therefrom through insulated nozzles 7, preferably in the form of jets. The jets create a turbulence in a downward direction in the bath and form a zone of reaction in the bath wherein there is a tendency in the upper portions of the zone tolift the granular material toward the extreme upper zoneof the bath.

Through the pipe 8 circulating water is introduced through insulated nozzles 10, the water functioning to create a turbulence H1 the bath in its passage to the bottom of the The'gaseous medium, preferably air which has been' strongly and controllably charged with electrical ions by passing over any suitable charging means, such as a corona, is introduced into the bath through the conduit 9, herein termed the gaseous ionization conduit, and the nozzles 11. The highly charged air is preferably introduced into the bath under a relatively high pressure. In my experiments I have found that satisfactory results are obtained bypressures varying between pounds per square inch and 75 pounds per square inch, although it is obvious this pressure may be varied in accordance with the requirements of-the material being treated and, therefore, it is not intended to limit the invention to any specific pressure. Under some circumstances, as in the case of the treatment of bugdust, the pressure necessary is only a few ounces per square inch. On the other hand, higher pressures than 7 5 pounds per square inch may be used.

The ionization conduit 9 is, as stated, provided with'a multiple series of nozzles 11 and preferably, these nozzles extend in a substantially horizontal direction so that the jets of highly ionized gaseous medium issuing therefrom assist in keeping the stabilizer in the upper zone of the bath, adjacent the front wall 17 of the cell 12. Directing the jets of highly charged gaseous medium as specified also functions to prevent the heavier granular material from sinking near the front wall 17 of the cell.

The highly and controllably charged gaseous medium issuing from conduit 9 through the nozzles 11 in a polarity opposite to the electrical characteristics of, the material being treated will form in the liquid bath 38 bubbles and the size thereof is approximately regulated by the size of the nozzle outlets.

The number of nozzles used and the pressure under which the gaseous medium is introduced will control the volume of the bubbles created. These bubbles are charged with electrical ions of the reverse polarity of'the material to be floated off the surface of the bath,

and therefore will be attracted by the oppov into the bath charged with negative ions, the

coal being treated having a positive electrical characteristic. The gangue in this case showed a neutral tendency. The bubbles, due to, the electrical attraction of a. negative charge to a positive charge, adhere to the granular material and-lift the same through the stabilizer, buoyant in the bath, to the top of the bath.

In carrying out the process on a granular material it isdesirable to introduce into the ucts, animal fats, plant fats, and aliphatic,

aromatic, and heterocyclic hydrocarbons, which are well known in theart. At this point it is desirable to indicate that while it IS preferable to introduce a flotation agent into the bath, under some circumstances my invention may be carried out in the absence of a flotation agent. This will be the, case when a very finely divided material is being treated as, for example, finely divided ore or coal bugdust, which is also in a finely divided condition.

The flotation agent may be introduced into the bath at various points. However, in the preferred mode of operating the oil is introduced in admixture with the circulating wa- I ter entering conduit 8. However, under some circumstances, the oil may be introduced in admixture with, the stabilizer entering the bath through stabilizer conduit 6. treating wet material, and as an example thereof, I may mention material derived froma previous treatment or passage through a previous cell employing the present process, the flotation agent may be introduced through oil feed pipe 71 located inside of the feed conveyor trough 72. When the flotation agent is introduced through the pipe 71, it mixes with the liquids contained invthe mass of wet product treated and the mixture passes under the gate 4, and along the inclined bottom 15 of the cell 12 to the zone of first turbulence created by the jets issuing from stabilizer pipe 6, the zone of turbulence being indicated by lines S and S, shown in Figure 2.

The flotation oil may also be introduced through the ionizing conduit 9 with the gaseous medium, such as air, in admixture therewith, preferably in the form of a vapor. Such oily vapors may be formed and mixed with the air prior to the passage of the air over the corona Wire 103. However, the oily vapors may also be mixed with the air after the passage of the air over the corona, this in a measure being dependent on the electrical characteristics of'the flotation agent used.

The degree of the'ionization bf the gaseous medium may be controlled by supercharging a portion thereof by passing it over the corona wire 103 and admixing it with a fresh portion of unionized gaseous medium and passing the resultant mixture into the bath.

In. all cases where the gaseous medium is Increases the adhesion of the bubbles to the created in the immediate vicinity of the ionization pipe nozzles are comparatively small while at the end of the turbulence created by the air et, that is adjacent to the front wall 17 of the cell, the bubbles are considerably larger. Substantially all of these bubbles will rise in their respective zones of creation and will have a tendency to rise through the bath in a vertical direction, being electrically charged with charges opposite to the polarity of the electrical ground 122, as shown in Figure 2, connected to the distributor or condensing gate 4 at the rear end 14 of the cell 12.

There is a migration of electrically charged air bubbles in the upper zone of the bath,

' this migration being induced by the condensing medium 4 and its proper ground connection 122. In this manner, the upper zone of the bath is permeated with air bubbles wh ch by migration toward the rear wall 14 of the cell 12 containing the condensing mean uncontrollable ionization since the natural reaction of any jet passing through a metallic nozzle and through air, and impinging on a liquid surface will entrain air which will be uncontrollably ionized in its passage to and into the surface of the bath. This uncontrollable ionization is usually so small as to be of little value. In contrast with the above, according to my invention, a voluntary and controllable ionization is employed.

As stated, the granular material being treated passes along the inclined cell wall 15'and .comes in cont-act with the zone of turbulence indicated by lines 8 and s. In this zone the heavier material or gangue is pushed forwardly toward the second zone of reaction indicated by the lines If and t and finally passes into gangue conveyor channel 21, and is conveyed therefrom by gangue conveyor 22. The valuable material or the cleaned coal by the reaction'of the first and I second zones of turbulences is raised up wardly into the stabilizer zone Where it is in contact with the migration of the electrically charged or ionized bubbles. From the stabilized zone the valuable material rises to the surface of the flotation bath and thereafter The valuable portion of the material being treated is removed from the bath by means of skimmer 47 into the product conveyor trough 55 and is discharged therefrom through discharge spout 59. The product issuing from spout 59 may again be treated by the process set forth until it attains the desired purity.

As referred to in the specific description of the cell, the bath is given a fluctuating motion, and this is particularly desirable in the treatment of coal, as my experiments indicate that valuable granular particles approaching the surface of the bath show a tendency to sink prior to breaking through the surface tension of the bath.

The fluctuation permits an easy breaking of the surface tension and therefore a greater .recovery of the valuable granular matter is attained. To regulate this fluctuation, drum 26 is utilized, and-the amount of liquid to be removed is made dependent upon the slot 28 and the number of revolutions of the drum, as previously described. It has been my experience that with very large granular materials, such as of mesh, the depth of the zone of fluctuation must be considerably deeper than with material passing through a mesh screen. Finely divided maternal such as passes through an 80 mesh screen and over require practically no fluctuation. 1

A specific example of the process is as follows: 300 pounds of refuse originating from a standard washery treating Alabama coal was treated in order to extract all the valuable coal therefrom. The refuse was in the form of an aggregate ranging in size between inch and fine granular particles, and comprised slate, rock, bone, laminated shale, and coal. The aggregate analyzed:

Per cent Volatile matter 16.75 Free carbon 23.85 Ash (including sulphur) 59.40

The refuse was first disintegrated to pass through a mesh screen and then introduced was injected at the rate of 3 gallons per minute, the passing of 300 pounds of coal through the cell requiring 1 hour. The circulating water which was used originated from the overflow sump of the washery from which the aggregate being treated was obtained and contained 120 grams or 7.2 ounces l per gallon of fine material, including granular material upto 18 mesh, and the bugdust into 'a cell through which circulating water therein functioned as the stabilizer in the process. The analysis of the stabilizer in dry state showed: A

There was introduced in the cell, a suitable quantity of pine oil, and air ionized by passing over a corona Wire carrying 32,000 volts.

The valuable material recovered from the cell was dried and separated into granular and dust material, the granular being from mesh to 80' mesh and the dust from 80 mesh to 200 mesh. Theanalysis of the granular matter recovered showed:

Per cent The dust recovered analyzed:

- Percent Volatile matter 27.5 Free carbon 56.4 Ash 16.1

The tailings from the first cell was passed into a second cell and tailingstherefrom passed into a third cell. The tailings recovered from the latter was passed through a fourth cell, all the cells employing the present process. The final tail product was subjected to the float and sinktest at 1.4 specific gravity and showed 0.5% of coal or 10 pounds per ton of gangue. The floatand sink test referred to is a standard testing process and utilizes a bath having a slightly higher specific gravity than the coal with its desired ash contents.

For the entire flotation treatment, in this particular case, pine oil at the rate A of a gallon per ton of finished coal was used.

In another test on refuse from the same mine, the air was passed overa corona wire carrying 35,000 volts and total pine oil utilized was of a gallon per ton of finished material.

The aggregate, prior to treatment analyzed: l

. Percent Volatile matter"; 23.6 Free carbon 39.6 Ash 36.8

rial analyzed Per cent The tailings from the first cell was re- 55 treated as previously described and the pass through one celL' Volatile matter 29.2-

From the above test it is seen that utilizing a air which has been passed over a corona wire carrying a higher voltage than in the previous test, the ash-content of the coal was greatly decreased, as compared with the first test, giving a quasi commercial coal in one In another test on Canadian coal from Cape Breton, the coal was treated by the present process to remove the high content of sulfur, appearing as sulfides, including pyrite, and amorphous sulfur. The test was made in a series. of five passes through the respective cells, and it was found that the total sulfur in the coal was reduced from an average of 12% to 0.75%, the total gangue extracted consisting of sulfur and ash was 14.5% of the weight of the coal treated. In this test a stabilizerwas used amounting to 12 ounces of 200 mesh bugdust per gallon of water injected through the stabilizer pipe. The ionization medium comprising air was passed over a corona of 32,000 volts and the charged air was introduced into the flotation bath. For the entire five passes 1.47 gallons of total oil was used, half of which was pine oil injected in admixture with the stabilizer. The other half of the flotation agent in the form of kerosene, was injected into the bath with the circulating .water, which in this case was clear water.

Various tests made clearly indicate the fact that the relation of the amount of material to be raised must be in a distinct proportion to the contents of the bath. In particular, if large granular material is treated, there must be sufficient space permitted between the ascending particles so that the bubbles are prevented from adhering to two pieces of granular material at the same time. It

has been noted that in cases of congestion one piece would be lifted and the other one forced to sink when the bubble adhering to both pieces burst on the surface of the bath.

My experiments to determine the actual relation between the mass to be raised and the bath, clearly indicate that preferably the mass should be around 12% in volume to that of the liquid when the mass being treated is granular coal. This percentage includes the stabilizer used as an admixture to the liquid of the bath. However, tests with particularly large granular matter, between 1; and inch mesh indicate that the volume of the mass may be somewhat less to the surface of the bath. If the upper regions of the bath are crowded with a larger number of granular particles, bubbles, through their electricalenergy, attach themselves to adjacent granular matter and thus the lifting power of the bubble is retarded by the rising of the granular matter'into the regions of the top of the bath. It further has been noted that the crowding of granular matter will rupture the bubbles and this decreases the efficiency of the process.

While I have given specific examples of the amount of liquid and the amount of aggregate compatable with each other to maintain such a pulp dilution as will permit the granular material to rise to the top zone of the bath, it is obvious that I do not wish to be limited to these specific percentages. Treating different materials of different sizes with different physical characteristics, it is clear that the percentage of liquid and aggregate compatible with each other will vary and therefore the relationship may be broadly set forth by stating that it must be of such a character as to permit the valuable granular material present in the bath to rise to the top surface of the bath and it is upon this broad statement of the relationship that I desire protection.

During the tests of relationship between the rising material and the fluid in the bath, it was noted, as previously stated, that bubbles bursting on the surface would, by force of reaction, repel granular material approaching the surface tension line of the bath, causing bubbles attached thereto to burst and forcing the granular material to descend in the bath. It has also been noted that very fine dust admixed with the bath would, without the aid of bubbles, rise toward the surface and in its upward motion toward the top zone of the bath have. its velocity retarded. This condition results when adjacent to the surface of the bath there is a zone permeated with this fine dust. Granular material also rising from the bottom toward the top by action of the turbulence and the bubbles, when once reaching this zone of stabilization, caused by the dust, has been found to ride upwards with the dust and come to the surface in a more ready manner than in a bath without the stabilizer. On the other hand, granular material from which the lifting bubbles are removed, do not show the tendency to sink as is the case when no stabilizer, is used. The stabilizer itself in this particular case having the same material characteristicsas the granular material gradually rises to the top of the bath and is skimmed off together with the granular material, as previously specified. Experiments have shown that the stabilizer can be charged, if of 100 to 200 mesh, at the ratio of 18 to 20 ounces of dry material per gallon of water injected through the stabilizer pipe. 'It

has also been shown by repeated tests that when granular coal approaching mesh is treated the amount of stabilizer in the bath should not exceed 25% in volume of the granular material to be raised. However, I do not desire to be limited to this particular percentage relationship as the percentage of stabilizer used will vary with the granulation of the material being treated. With mosh coal considerably less stabilizer will be used. With dust no stabilizer will be necessary. What I desire to broadly set forth is that the relationship between the volume of the stabilizer and the volume of the granular material being treated should be such as to retard the sinking tendency of the granular material approaching the surface of the bath and the zone immediately adjacent thereto. Stated differently and more specifically, the volume of the stabilizer present in the bath is proportioned to the volume of the granular material present in the bath so as to retard the sinking tendency of the granular material approaching the surface of the bath and the zone immediately adjacent thereto.

YVhile the most satisfactory method of charging the gaseous medium is by passing over a corona discharge, I desire to state that the gaseous medium may also be charged by passing it through an X-ray apparatus, such as the Coolidge apparatus. Not only can X-rays be used to highly and controllably charge the gaseous medium, but other rays, including ultra-violet rays, may be used.

While in my preferred mode of procedure I have stated that the gaseous medium is passed under pressure over the corona or over the other medium used to charge the gases or air, I, of course, do not mean to limit myself to passage of air under pressure as it is,'of course, obvious that this air may be passed under pressure over the corona or other charging medium under suction.

Under some circumstances it may be desirable to mix the ionized air with the stabilizer fluid or with the circulating liquid.

In the claims, the phrase passing into the bath a gaseous medium externally strongly and controllably charged with electrical ions and similar terms are to be construed to cover the passage into the bath of a gaseous medium which is charged prior to its introduction into the bath with electrical ions of either polarity and of any desired potentialcontrollably charged prior to its introduction into the bath and at will with electrical ions of either polarity and of any desired p0 tentiality, both of these characteristics of the electrical ions being predetermined and depending upon the electrical characteristics of the bath as an entity and including the electrical characteristics of the material treated,

. charge to controllably charge the same prior to its introduction into the bath with electrical ions of either polarity and of any desired potentiality, both the latter being predetermined and depending upon the electrical characteristics of the bath as an entity and including the electrical characteristics of the material being treated, delivering said gaseous medium with its controlled charge to the flotation bath and the material being treated present therein, and separately collecting the valuable material and the gangue.

3. The process of separating materials of different specific gravities by flotation wherein a flotation bath is employed comprising passing into the flotation bath, a buoyancy stabilizer and a gaseous medium controllably charged prior to its introduction into the bath and at W111 with electrical ions of either polarity and of any desired potentiality, the charactor of the electrical ions being predetermined and depending upon the electrical characteristics of the bath as an entity and including the electrical characteristics of the material treated, and separately collecting the valuable'material and gangue.

-4.,The process of separating materials of different specific gravities by flotationwherein a flotation bath is employed comprising passing into the bath a gaseous medium externally strongly and controllably charged with electrical ions, controlling the accumulation of the static charge in the bath, and separately collecting the valuable material and a gangue. v

5. The process of separating materials of different specific gravities by flotation wherein a flotation bath is employed comprising passing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, preventing the accumulation of a static charge in the bath by condensing the static charge, removing the condensed charge from'the bath, and separately collecting the valuable'material and a gangue.

6. The process of separating materials of difl'erent specific gravities by flotation wherein a flotation-bath is employed comprising passing into the bath ,a buoyancy stabilizer, and a gaseous medium external y, strongly ions, preventing the accumulation of a static charge in the bath by condensing the same, removing the condensed charge from the bath, and separately collecting the valuable material and a gangue.

7. The process of separating materials of different specific gravities by flotation wherein'a flotation bath is employed comprising passing in the bath a buoyancy stabilizer and a gaseous medium externally, strongly and controllably charged with electrical ions, creating a zone of fluctuation of the bath at or near the surface thereof, and separately collecting the valuable material and a gangue.

8. The process of separating materials of different specific gravities by flotation wherein a flotationbath is employed comprising passing into the bath a buoyancy stabilizer and a gaseous medium externally, strongly and controllably charged with electrical ion's, preventing the accumulation of a static charge in the bath by condensing the same, removing the condensed charge from the bath,creatingazone of fluctuation of the bath adjacent the surface thereof, and separately collecting the valuable material and a gangue.

9. The process of separating materials of different specific gravities having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising maintaining a pulp dilution permitting unhindered rising of the granular particles, passing into the bath a gaseous medium externally strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

10. The process of separating materials of different specific gravities having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the bath a buoyancy stabilizer and a gaseous medium externally, strongly and controllably charged with electrical ions, maintaining a pulp dilution permitting the granular particles to rise unhindered to the top'zone of the bath, and separately collecting the valuable material and a gangue.

11. The'process o." separating materials of different specific gravities having a valuable portion and a gangue, by flotation wherein a flotation bath is employed comprising passing in the bath a buoyancy stabilizer and a gaseous medium externally, strongly and controllably charged with electrical ions, preventing the accumulation of a static charge in the bath by condensing the same, removing the condensed. charge from the bath, maintaining a pulp dilution permitting unhindered rising of the granular particles, and separately collecting the valuable material and a gangue. i 7

12. The process of separating materials of 55 and controllably changed with electrical different specific gravities having a valuable portion and a gangue by flotation wherein a flotation bath is employed, comprising passing in the bath a buoyanc stabilizer and a gascous medium external y, strongly and controllably charged with electrical ions, preventing the accumulation of a static charge in the bath by condensing the same, removing the condensed charge from the bath, maintaining a pulp dilution permitting unhindered rising of granular particles, creating a zone of fluctuation of the bath adj acent the surface thereof, and separately collecting the valuable material and a gangue. '13. The process of separating materials of difl'erent specific gravity by flotation wherein a flotation bath is employed comprising passing into the flotation bath a buoyancy stabili'zer substantially of the same character as the material being treated, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

14. The process of separating materials of different specific gravity including a valu- T able portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the flotation bath a buoyancy stabilizer having the same general charactzristics as the valuable portion of the material being treated and adapted to be included in the final product, introducing into said bath a gaseous medium which has been externally, strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

15. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation both is employed comprising passing into the flotation bath a buoyancy stabilizer comprising finely ground coal, introducing a gaseous mediumexternally, strongly and controllably charged with electrical ions, and collecting granular coal and a gangue.

16. The process of separating materials of diflerent specific gravities having a valuable portion and a gangue by bubble flotation wherein a flotation bath is employed comprising separately passing into the bath a buoyancy stabilizer independent of the supply of material being floated, controlling the relationship between the amount of liquid being treated and the amount of solid material including the stabilizer present in the bath to maintain such a pulp dilution as will permit the valuable-portion of the material to rise substantially unhindered to the top zone of the bath, proportioning the amount of buoyancy stabilizer present in the bath to the amount of material treated present in the bath so as to retard the sinking tendency of the valuable material approaching the top zone of the bath, and separately collecting the valuable material and a gangue.

17 The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a buoyancy stabilizer consisting of finely divided coal into the bath, controlling the relationship between the amount of liquid being treated and the amount of solid material including the finely divided coal present in the bath to maintainsuoh a pulp dilution as will permit the coal to rise substantially unhindered to the top zone of the bath, proportioning the volume of the finely divided coal stabilizer present in the bath to the volume of the granular material present in the bath so as to retard the sinking tendency of the granular coal, approaching the top zone of the bath, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

18. The process of separating materials of different specific gravitles by flotation wherein a flotation bath is employed comprising creating separate zones of turbulence in the flotation bath by passing therein circulating Water, a buoyancy stabilizer, a gaseous medium which has been externally, strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

19. The process of separating coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising creating separate zones of turbulence by passing therein circulating water, a buoyancy stabilizer consisting of finely divided coal, a gaseous medium externally, strongly and controllably charged with electrical ions, and separately collecting coal and a gangue.

20. The process of separating materials of diflerent specific gravities having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the bath a buoyancy stabilizer, controlling the relationship between theamount of liquid being treated and the amount of solid material including the stabilizer present in the bath to maintain such a pulp dilution as will permit the valuable portion of the material to rise substantially unhindered to the top zone of the bath, proportioning the volume of the stabilizer present in the bath to the volume of the material being treated present in the bath so as toretard the sinking tendency of the valuable material approaching the top zone of the bath, passing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and separately collecting the valuable material and a gangue.

21. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath ill) l'ib

ibU

, to the volume of the granular material presis employed comprising passing a finely divided buoyancy stabilizer into the bath,.controlling the relationship between the amount of liquid being treated and the amount of solid material including the finely divided stabilizer present in the bath to maintain such a pulp dilution as will permit the granular material to rise unhindered to the top zone of the bath, proportioning the volume of finely divided stabilizer present in thebath ent in the bath so as to retard the sinking tendency of the valuable granular material approaching the top zone of the bath, passing into the bath a gaseous medium externally, strongly and controllably charged with electrical vions, and collecting coal and a gangue.

22. The process of treating coal, by flota tion wherein a flotation bath is employed, c'omprisingsubjecting the coal to treatment in the presence of-a gaseous medium externally, strongly and controllably charged with electrical ions, and seprately recovering coal and a gangue.

23; The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the batha gaseous mediuln externally, strongly and controllably charged with electrical ions, preventing the accumulation of a staticcharge in the bath, and separately collecting coal and a gangue. v

'24. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the bath a gaseous medium which has been passed over a corona discharge, preventing the accumulation of a static charge in the bath, and separately collecting coal and a gangue.

25. The process of separating granular coal, aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, preventing the accumulation of a static charge in the bath by condensing the static charge and removing the condensed charge from the bath, and separately collecting coal and a gangue.

26. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a buoyancy stabilizer into the bath, introducing in said coal and a gangue.

29. The process of separating coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising controlling the relationship between th amount of'liquid bein treated and the amount of solid material mcluding the coal present in the bath, to maintain such a pulp dilution as will permit the coal to rise substantially unhindered" to the top zone of the bath, introducing into the bath a gaseous medium externa 1y, strongly and controllably charged with electrical ions, and separately collecting coal and a gangue.

30; The process of separating granular .coal aggregatehaving a valuable portion and collecting e bath a gasstabilizer into the bath, controlling the relationship between the amount of liquid being treated and the amount of solid material including the coal present in the bath to maintain such a pulp dilution as will permit the granular coal to rise substantially unhindered to the top zone of the bath, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and separately collecting coal and a gangue.

31. The process of separating granular coal aggregate having a valuable portion and gangue by bubbleflotation whereina flotation bath is employed comprising separately passing into the bath a finely divided stabilizer independent of the supply of the material being floated, controlling the relationship between the volume of the stabilizer and the volume of granular material present in thebath to maintain such'a pulp dilution' as will retard the sinking tendency of the granular material approaching the surface of the bath and the zone adjacent thereto, and collecting coal anda gangue.

32. The process of separating granular coal aggregate having a valuable portion and gangue by bubble flotation wherein a flotation bath is employed comprising separately passing into the bath a stabilizer of finely divided coal, said stabilizer being independent of the supply of material being floated, controlling the relationship between the volume of the stabilizer and the volume of granular material present in the bath to maintain such a pulp dilution as will retard the sinking tendency of the granular material approaching the surface of the bath and the zone adjacent thereto, and collecting coal and a gangue.

33. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a stabilizer of finely divided material into the bath, controlling the relationship between the volume of the stabilizer and the volume of the granular material present in the bath to maintain such a pulp dilution as will retard the sinking tendency of the ranular material approaching the surface 0 the bath and the zone adjacent thereto, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and collecting coal and a gangue.

34. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a stabilizer of finely divided coal into the bath, controlling the relationship between the volume of the stabilizer and the volume of the granular material present in the bath to maintain such a pulp dilution as will retard the sinking tendency of the granular material approaching the surface of the bath and the zone adj acent thereto, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and collecting coal and a gangue.

35. The process of separating granular coal aggregate having a valuable portion and a gangue by bubble flotation wherein a flotation bath is employed comprising separately passing into the bath a buoyancy stabilizer independent of the supply of material being floated, controlling the relationship between the amountof liquid being treated and the amount of solid material including coal present in the bath to maintain such a pulp dilution as will permit the coal to rise substantially unhindered to the top zone of the bath, proportioning the volume of the stabilizer present in the bath to the volume of the granular coal present in the bath so as to retard the sinking tendency of the granular coal approaching the top zone of the bath, and collecting coal and a gangue.

36. The process of separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a stabilizer into the bath, controlling the relationship between the amount of liquid being treated and the amount of solid material including coal present in the bath to maintain such pulp dilution as will permit the coal to rise substantially unhindered to the top zone of the bath, proportioningthe volume of the stabilizer present in the bath to the volume of the granular coal present in the bath so as to retard the sinking tendency of the granular coal approaching the top zone of thebath, introducing into the bath a gaseous medium externally, strongly and controllably charged with electrical ions, and collecting coal and a gangue.

37. The process of separating granular coal aggregate having a valuable portion and a gangue by bubble flotation wherein a flotation bath is employed comprising passing a stabilizer consisting of finely divided coal into the bath, controlling the relationship between the amount of liquid being treated and the amount of solid material including the finely divided coal present in the bath to maintain such a pulp dilution as will permit the coal to rise substantially unhindered to the top zone of the bath, proportioning the volume of the finely divided coal stabilizer present in the bath to the volume of the granular material present in the bath so as to retard the sinking tendency of the granular coal approaching the top zone of the bath, and collecting coal and a gan ue.

38. The process -0 separating granular coal aggregate having a valuable portion and a gangue by flotation wherein a flotation bath is employed comprising passing a stabilizer consisting of finely divided coal into the bath, controlling the relationship between the amountof liquid being treated and the amount of solid material including the finely divided coal present in the bath to maintain such a pulp dilution as will permit the coal to rise substantially unhindered to the top zone of the bath, proportioning the volume of the finely divided coal stabilizer present in the bath to the volume of the granular material present in the bath so as to retard the sinking tendency of the granular coal approaching the top zone of the bath, introducing into the bath a gaseousmedium externally, strongly and controllably charged with electrical ions preventing the accumulation of a static charge in the bath, and collecting coal and a gangue.

39. The process of separating granular coal aggregate having a valuable portion and a gangue by bubble flotation wherein a flotation bath is employed comprising passing a stabilizerconsistingof finely divided coal into the bath, controlling the -relationship between the amount of liquid being treated and the amount of solid material including the finel divided coal in the bath to maintain sue a pulp dilution as will permit the coal to rise substantially unhindered to the top zone of 'the bath, proportioning the volume of the finely-divided coal stabilizer present in the bath to the volume of the granular material present in the bath 'so as to retard the sinkp ing tendency of the granular material approaching the top sur ace of the'bath, pre-' venting an accumulation of a static charge inthe bath by condensing the same and removing the condensed charge from the bath,

creating a zone of fluctuation of the bath.

adjacent the surface thereof, and collecting coal and a gangue.

- 40. The process. of separating materials of different specific gravities by flotation wherein a flotation bath is employed, comprising creating separate zonesof turbulence in the flotation bath by passing therein circulating water, a stabilizer, and a gaseous medium which has been passed over a corona discharge and collecting the valuable products j and gangue.

41. The process of separating coalaggregate having a valuable portion and a gangue flotation wherein a flotation bath is emp oyed comprising creating separate zones of turbulence in said bath by passing therein water, a stabillzer consistin of circulating finely divided coal, and a gaseous me ium which has been passed charge and collecting coal 'anda gangue.

In testimony whereof I hereunto aflix my signature.

v FREDERICK TSCHUDY.

over a corona dis-