US2189779A

US2189779A - Emulsifying means and method

Info

Publication number: US2189779A
Application number: US63578A
Authority: US
Inventors: Arthur C Daman
Original assignee: Mining Process and Patent Co
Current assignee: Mining Process and Patent Co
Priority date: 1936-02-12
Filing date: 1936-02-12
Publication date: 1940-02-13
Anticipated expiration: 1957-02-13

Description

Feb. 13, 1940. A. c. DAMAN 2,189,779

EMULSIFYING MEANS 'AND METHOD Filed Feb. l2, 1936` 2 Sheets-Sheet l limit;

WS 7 Ik IlI a* f Saws s Y A INVENTOR.

ARTHUR C. DAMA/ v @edf '5 ,f \v

ATTORNEY.

Feb. 13, 1940. A. c. DAMAN l 2,189,779

EMULSIFYING MEANS AND METHOD Filed Feb'. 12, 193s Y 2 sheets-sheet 2 INV ENTOR. ARTHUR C- DAMA/V Y BY Vlueur-l Feb. 113,' mev PATsur ori-ICE y ammo EMULSIFYING MEANS AND METHOD Arthur C. Daman,- Denver, Colo., assigner, by

meme I assignments, to

essand Patent Company, a corporation of Delaware Application February 12, 19.36,' Serial No.` 63,578

18 Claims. (Cl. 208-168) My invention lrelates to emulsiilers, and more particularly relates to emulsiiiers of the type in which a gas is intimately lntermixed with one or more fluent constituents of a material under 5 treatment. The invention also relates to a method of emulsifying fluent materials.

While the apparatus herein disclosed is intended for use wherever a general emulsifying action is to be produced, it is particularly eicacious in l emulsifying various fluent materials in ore treatments. f

It is an object of the present invention to combine an emulsifying action with the froth flotation separation of ores, and more particularly to 15 add to the froth flotation treatment what may be termed a booster during the separation of values from other pulp constituents, whereby a cleaner separation of values may be effected than has heretofore been possible. l

yn Another object of the invention is the production of an intimate intermixture of values, gas and reagent in the separation zone of a flotation treatment without materially altering the quiescent character of such zone.

i, A further object of'. the invention resides in the provision of simple, durable, and eilicient emulslfying apparatus that may be readily adapted for a variety of uses.

Still another object of the invention resides in :nl the provision of apparatus for general application in the separation chamber of froth flotation machines and effective as a booster for increasing the recovery of values therein.

Other objects reside in novel steps and treat- :l s ments and novel combinations and arrangements of parts as will more fully appear in the course of the following description:

In the drawings, in the several views of which like parts have been similarly designated,

lo Figure 1 represents a vertical section through an emulsier tank, and the first two cells of a froth otation machine, each of which is provided with an emulsiiier booster in the separation chamber;

1" Figure 2 is a section taken along the line 2 2,

Figure l;

Figure 3 is a section taken along the line 1 3,

Figure 1;

Figure 4 is a section taken along the line 4-4, Figure l;

Figure 5 is a section taken along the line #-5,

Figure l;

Figure 6 is a section taken along the line @-4,l

55 Figure 1;

Figure 1; and

Figure 8 is a section taken along the line 8-8. Figure 1.

An emulsifier has been illustrated in Figure 1 5 as embodying the features of my invention, and comprises a tank 9 preferably provided with a su'mp Ill vin which an opening I2 is normally fitted with a threaded plug I3.

The tank is intended for constant operation, 10 subject to a continuous feed and discharge, and to this end, a feed inlet I4 at any selective elevation is connected with a suitable source of, feed (not shown), while a discharge outlet I5, also disposed at any selective elevation, determines a l5 liquid level in the tank 9.

The dotted lines projecting from the tank 9 in Figure 1 indicate different positions of the feed inlet I4, and discharge outlet I5, which may be used, it being understood that these are mere- 1y illustrative of the variety of positions which may be selected.

A rotary shaft I6 extends through the tank 9 and carries a plurality of impeller elements I1 at predetermined intervals. An elevating spiral I8 25 is mounted at an end of shaft I 6, and extends through an opening I9 in the bottom of the tank 9 into the sump I0.

The impeller element I1 may be of any type effective for pumping fluent material, but preferably consist of a hollow hub 20 and a at disk or plate 2l extending transversely therefrom. The hubs 20 are intended to be slidable along the shaft I6 to initially position the disks 2l, and are frictionally held in position by keys 22, or other-* suitable fastening devices, for conjoint rotation with shaft I6.

Best results are attained when the several disks 2| rotate as a unit and to this end the respective hubs 25 are provided with a tongue 23 at one' 40 end and a groove 24 at the opposite end in order that the tongues of one hub may t in the grooves of the next adjoining hub.

A series of annular bailles 25 are ftened on the walls of. the tank 9 and have a central opening 45 26 of somewhat greater diameter than the diameter of the hubs 2lil to provide a passage for material under treatment. One of the baiiles 25 is disposed above and in spaced relation to each of the disks 2 I. 50

A second series of annular bailles 21 are mounted on spiders 28 fastened to the walls of tank 9, and the central openings 29 of the bailles are of only slightly greater diameter than the diameter of hubs 20, which they encompass in order that material in the tank will not be free to pass between the baffles 21 and hubs 20. Each baille 21 is disposed beneath and in spaced relation to one of the disks 2I.

The foregoing arrangement insures a circuitous travel to material in the tank between the inlet and outlet, during which it is acted on at successive stages by the respective disks 2|. The arrows in tank 9 in Figure 1 illustrate a movement of material under the influence of centrifugal action of the disks.

It will sometimes be desirable, as for example, when the tank is used as a conditioner for a froth flotation treatment, to introduce reagent into the material under treatment.

A launder 30, leading into the tank 9 receives reagent from a suitable feeding device (not shown), and when desired may also be used as a feed inlet.

In certain treatments, a vigorous frothing will occur. and a baille 3| in the upper end of tank 9 acts as a froth crowder to confine the frothing within the tank. A stuffing box I 3l about shaft I6 is detachably held on baille 3| and may be removed when additional aeration induced by a vortex created by the impellers I1 is desired.

The apparatus thus far described is a complete unit by itself, and is effective in producing an intimate intermixture of air and one or more fluent materials under treatment, or of the fluent materials only.

The rotation ofthe impellers I1 creates a vorfrom launder 39 will be acted on successively by the several impellers and intimately intermixed thereby.

The pumping action of any impeller is sufficient to draw toward its periphery material adjoining the hub of the impeller next adjacent, and in this way the progressive movement of material from disk to disk is effected.

The spiral screw I8 in the sump imparts an upward thrust to material therein. As a result any heavier constituents in the material in the tank 9 are not free to settle into the sump I0, but are maintained in suspension by the agitation imparted by the disks 2|.

If desired, the plug I3 may be removed and the sump opening I2 may be connected with any suitable source of feed supply.

Material fed into the sump III will be acted on by the screw I 8, and elevated into tank 9, where it will be subjected to 'the action of the disks.

It will be apparent that the direction of travel of material in the tank will be governed by the relative positions of the inlet I4 and outlet I5. If the inlet is at a lower elevation than the outlet, the material will travel in a circuitous upward path, while if the inlet is above the outlet, a progressive downward circuitous movement results.

It will be understood that when material is moved upwardly in the tank the position of the baffles 25 and 21 is reversed relative to impellers I 1 and the material is subjected to alternate suction and centrifugal influences.

In addition to its use as a separate treatment unit, the invention may also be embodied in other types of treatment tanks where an emulsifying action is desired, as a supplement to existing treatments.

As an example of this arrangement, the emulsifier has been illustrated as a unit applied to the first and second cells of a froth flotation machine, with the apparatus hereinbefore described also illustrated as an emulsifying conditioner preceding flotation.

The flotation machine of the drawings represents a typical Denver Sub-A machine, certain features of which have been shown and described in my co-pending application, Serial No. 566,987, filed October 5, 1931, Patent No. 2,031,590, issued February 25, 1936.

This machine comprises a tank 32 divided by double partitions 33a and 33h into a series of flotation cells. A bowl 34 is fitted in the bottom of each cell, and a rotary impeller 35 is suspended on a shaft 36 and extends into the bowl.

'I'he walls or partitions 33a form the rear wall of each cell of the series, and the walls or partitions 33b form the front wall of each cell. The space between adjoining walls 33a and 33h is a feed passage or compartment 31, which, at its upper end, is open to the atmosphere.

The upper portions of walls 33h are slotted as indicated at 38 and a gate 39 slidably mounted on a face of wall 33h is controlled by a Vhand screw 40 to selectively open and close the passage defined by the slot 38. A similar hand screw 40a controlling a sliding plate 59 on the wall 33a provides an adjustable Weir regulation for establishing a liquid level in the cell.

An opening 4I in one of the side walls of the compartment 31 is normally closed by a removable plug 42, which permits removal of any values which may be trapped in the lower portion of the compartment.

A hollow column 43 encompasses the shaft 36 and extends from an elevation above the liquid level into the lower portion of the cell where it terminates in a flaring hub 44. A cover plate or hood 45 is attached to the lower end of the hub 44 and extends laterally therefrom adjacent but in spaced relation to the impeller 35. Suitable openings may be provided in the hood for recirculation of material to the impeller.

A conduit 46 fltted in openings 41 and 4B in the wall 33h and column 43 respectively is provided to conduct feed from compartment 31 directly to the impeller 35 by gravity. An opening 49 in the hub 44 opposite opening 48 is normally closed by a plug 50, but may be connected with a suitable conduit where desired for the return of froth or middlings to the cell.

Each cell is divided by a grid 5I into a lower agitation compartment 52, and an upper separation compartment 53. Suitable baffles 54 may be disposed to restrain agitation in the agitation compartment, and in the drawings are shown as of integral construction with the hub 44.

An opening 55 through the bottom of the machine is normally closed by a plug 56 and permits cleaning of the cell when necessary. This opening may also be utilized to admit a branch 51 from a suitable feed source (not shown) which may also be connected with a pipe 5B leading from a source of air or other gas under pressure (not shown).

A froth crowder 60 extends into the separation compartment 53 to a lower elevation than the liquid level, and prevents froth from passing over the Weir 59. In Figure 5, a froth launder Air is entrapped in the feed in compartment 31` by the cascading of pulp and by the suction inuence of the impeller and passes into the impeller with the pulp.

Air is also drawn down through column 43 by the pumping action of the impeller and the converging streams of air and aerated pulp thrown together in the hub are beaten by the blades and thrown outwardly into the agitation chamber.

If desired, the impeller 35 may be provided with vanes on either or both surfaces to act on material under treatment disposed above and below the impeller. Likewise openings may be provided in the impeller with cooperating baiiies which would effect a pumping action through the openings to increase the mixing function.

Due tothe resulting intermixture of these materials, the values acted on by the conditioning agent are elevated by the ascending air bubbles and carried into the separating chamber, and on to the surface where they are collected in a froth, and are subsequently removed by overflow as a concentrate.

The treated pulp remaining in the cell escapes across the weir 59, and the same treatment is repeated in .successive cells. If desired, froth from any given cell may be returned to another cell for retreatment by a connection through the opening 49 or branch 51, as previously described.

In the described treatment it frequently occurs that a certain percentage of the elevated values will not readily pass into and adhere to the froth layer.

To increase the eiilciency of the process the present invention adds an emulsifying booster in the separation compartment, which further conditions and aerates the elevated values'and insures a maximum collection and concentration of values.

To carry out the foregoing, an emulsiler unit 63, including a plurality of rotary impellersI 64 mounted on shaft 36, and a housing 65 supported from the column 43, is positioned in the separation zone with the upper end ofthe housing adjacent the liquid level in the cell.

Where it is contemplated that the unit 63 will laterbe added to the machine, the column 43 can be made in two or more sections tted together. At the time of installation of unit 63, the upper section of column 43 is removed and the housing 65 is fitted on the lower section of column 43 as indicated in Figure 1.

The upper section of column 43 is then fitted onto the upper end of housing 65 and the machine is again in condition for operation. To reduce vibration of this upper section a yoke 66 at its upper end may be connected with a bearing 61 on shaft 36.

The housing 65 is'provided at its upper end with an adjustable collar 68. Brackets 69 project inwardly from the upper' end of housing 65 and suspend a cover plate or hood 10 above and in spaced relation to the uppermost impeller 64. The hood 10 is suitably apertured as indicated at `'Il in Figure 5, for the recirculation of supernatant matter into the zone of influence of the upper impeller.

Intermediate the-ends of housing 65, brackets 69a carried on the housing suspend a double plate unit' comprising an under cover plate 12 for the uppermost impeller 64, and an upper cover plate 13 for the lowermost impeller 64, the two plates being joined by a connecting wall 14.

Brackets 691) project from housing 65 to an under cover plate 15, which has a channeled bottom 16 fitted upon the upper end of the lower section of column 43. This construction gives the unit a rigid connection from below as well as from above and prevents any considerable vibration of housing 65.

Where vibration is not a problem, the housing 65 may be suspended from above in the manner hereinabove described, and the brackets 69h will be omitted. Plate in this construction is independent of housing 65, and is tted on column 43 as previously described.

Each of the plates 10, 12, 13 and 15 is provided with recirculation openings 1| of the type already described. In addition, the plate 10 is also apertured to admit one or more pipes 11 which extend above the tank. 'I'hese pipes are utilized as conduits for air drawn in by the suction iniiuence of irnpellers 64. It is also possible to utilize these pipes 11 as conduits for air or other gas under pressure by connecting them with a suitable supply, and they may be further utilized in the supply of reagent by connection with a. suitable reagent feeder (not shown).

Braces 18 extending to the upper end of column 43 from the cell walls further aid in restraining vibration of the unit 63.

Whiley any form of impeller suitable for the purpose may be used-in the unit, it will be advantageous, under most conditions, tov use the impeller construction shown in Figure l.

The upper impeller is in the form of a flat plate or disk carried on a hub 19, produced by bolting two complementary sections 64a and 64b together. One or more apertures 80 are provided in each section to aid agitation. Vanes'8l on the plate further aid agitation and pumping.

While these vanes have been shown on the underside of the plate only, in Figure 1, it will be understood that they may be disposed on both the top and bottom faces or" only on the top face, as desired.

The lower disk 64 is of unitary construction, but instead of -being iiat, is of dished contour to impart an upward thrust by centrifugal action to material descending onto the plate. This plate is also provided with openings 80.

To further aid the circulation of material within housing 65, the housing is provided with openings 82 and the upper section of column 43 adjacent the collar 68 is also apertured as indicated at 63. y

From the foregoing it will be apparent that material inclusive of values will be drawn into housing 65 thru its open bottom and overfiowed across the collar 68 and into openings 83 at the top. Likewise the suction influence of the impellers 64 will draw in material thru the openings 482 with the result that a continuous circulation of material from separation chamber 53, into and out of the interior of housing 65 is effected.

Material approaching the uppermost impeller from above and beneath the same is drawn in, aerated and thrown outwardly by the centrifugal action. Hood 10 serves to impart a downward movement to material traveling on top of the impeller and cover plate 12 imparts an upward thrust to material moving along the lower face of said impeller with the result that the two streams converge at the periphery of the impeller effecting an intimate intermixture.

Vanes Ii beat the material moving outwardly along plate 12 which further aids the mixing action previously described. No vanes have been shown on the lower Vdisk Il, but it is apparent that the same may be used when desired.

The action in the lower part of housing 85 is similar to that herein described. 'I'he dished surface of the disk 64 imparts an upward thrust to material while hood 1I directs material downwardly toward the disk and plate 15 also directs material upwardly under the disk. These streams converge adjacent the periphery and an intimate intermixture of materials is produced thereby.

In using the aforementioned structure, some difficulty may be experienced in supplying sufilcient air to the impeller 35 to meet the requirements for proper treatment. Air under pressure may be admitted through pipe 58 which can be connected with a suitable source oi supply, when available.

Likewise, a conduit 52 may be connected in an opening in cover plate and extended through

compartments

52 and 53 into the atmosphere. If desired, a pressure gas may be supplied through this conduit, or if not, the suction iniluence of the impeller 45 will draw in considerable quantities of atmospheric air. If the emulsiiler produces a partial seal at the lower end of column Il, then it is necessary to admit air through pipe 92.

If it is preferred not to extend an air conduit into the agitation zone where it would be subjected to abrasion from the gritty pulp, a pipe 93 may be connected to the column 43 in the separation zone 53, and extended upwardly above the liquid level in the cell.

While the

pipes

92 and 93 are shown as applied to particular cells, it will be understood that either form may be used for any selective cell, or for an entire machine.

supernatant matter in the separating chamber 53 is constantly drawn into housing 65 and column 43 through the various openings, and subjected to vadditional aeration and agitation. A reagent or reagents having a preferential affinity for the values to be recovered may be introduced through one or more of the pipes 11 and intimately intermixed with supernatant matter and pulp acted on by the impellers.

The addition of slight amounts of reagent at this stage of the flotation treatment will result, in many instances, in a much higher concentration of values than is otherwise possible, and this is particularly true in the last cell or cells of a multi-cell machine.

Likewise, in some treatments, additional aeration and/or agitation provided in the frothing zone or adjacent the froth will effect an increased recovery of values, and may be availed of with the present invention, even if additional reagent is not required.

Under certain conditions, it will be desirable effectively restrain the agitation so that no pronounced disturbance occurs in compartment 53 when the unit 63 is in operation, and any gangue which has passed into the compartment will be free to settle and return to the agitation compartment 52.

From the foregoing it will be apparent that the emulsiiier unit 63 and the emulsifier illustrated as a conditioning tank 9 preceding flotation, embody one and the same invention.

An essential of both constructions is that material under treatment is at all times subject to the action of the rotary impellers. I'he partitions 25 and 21 of tank 9, and the plates 10, 12, 13 and 15 of unit 63 function with the respective impellers of these structures to direct the material in a circuitous passage through the same.

At all times in its circuitous travel, the material is subjected to the influences of the impellers, being alternately subjected to suction and centrifugal influences. When desired, air or reagent or both may be introduced into the material which is intimately intermixed and diffused by the action above described.

Changes and modications may be availed of within the spirit and scope of the invention as defined in the hereunto appended claims.

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

1. The combination with flotation apparatus, inclusive of an agitation chamber and a separation chamber interconnected for the iiow of material from one to the other, of an emulsifying unit in the separation chamber, comprising a housing having top and bottom passages to admit matter from the separation chamber, a rotary impeller in the housing for agitating and mixing material entering the housing, and a conduit supporting the unit and having an inlet in the housing and a discharge outlet in the agitation chamber.

2. The combination with a froth ilotation cell, including a separation chamber and a therebelow agitation chamber interconnected for the iiow of material from one to the other, and having an overflow determining a liquid level in the cell, of an emulsifying unit comprising an open-ended housing supported in an upright position in the separation chamber, with its upper end in proximity to the liquid level and acting as an overflow for froth and with its lower end admitting unfloated material thereto, a rotary impeller in the housing for mixing materials entering from the separation chamber through the respective ends of the housing, and opposed baffles covering the impeller and slanting in converging relation toward its periphery, whereby materials delivered to the impeller from opposite ends of the housing are ejected in converging streams to intimately intermix the same.

3. The combination with a froth otation cell, including a separation chamber and a therebelow agitation chamber interconnected for the flow of material from one to the other and having an overflow determining a liquid level in the cell, of an emulsifying unit comprising an open-ended housing supported in an upright position in the separation chamber, with its upper end in proximity to the liquid level and acting as an overflow for froth and with its lower end admitting unfioated material thereto, means for introducing a gas into the housing, a rotary impeller in the housing for mixing materials entering from the separation chamber through the respective ends of the housing, and opposed bailies covering the,

impeller and slanting in converging relation toward its periphery, whereby materials delivered to the impeller from opposite ends of the housing are ejected in converging streams to intimately intermix the same.

4. The combination with a froth flotation cell, including a separation chamber and a therebelow agitation chamber interconnected for the ow of material from one to the other, and having an overiiow determining a liquid level in the cell, of an emulsifying unit comprising an open-ended housing supported in an upright position in the separation chamber, with its upper end in proximity to the liquid level and acting as an overiiow for froth and with its lower end admitting unfioated material thereto, means for introducing a flotation reagent into the housing. a rotary impeller in the housing for mixing materials entering from the separation chamber through the respective ends of 'the housing, and opposed baflles covering the impeller and slanting in converging relation toward its periphery, whereby materials delivered to the impeller from opposite ends of the housing are ejected in converging streams to intimately intermix the same.

5. The combination with a froth flotation cell, including a separation chamber and a therebelow agitation chamber interconnected for the ow of material from oneto the other, and having an overiiow determining a liquid level in the cell, of an emulsifying unit comprising an open-ended housing supported in an upright position in the separation chamber with its upper end normally in proximity to the liquid level and acting as an overflow for froth and with its lower end admitting unoated material thereto, a rotary impeller in the housing for mixing materials entering from the separation chamber through the respective ends of the housing, and an element adjustably mounted at the upper end of the housing to lvary its effective elevation relative to the cell overow.

6. The combination with flotation apparatus, inclusive of an agitation chamber and a separation chamber interconnected for the flow of material from one to the other, of an emulsifying unit in the separation chamber, comprising a housing having top and bottom passages to admit matter in 'suspension from diiferent elevations in the separation chamber, and having a plurality of recirculation openings intermediate the top and bottom passages for the admission of matter from the separation chamber, and a rotary impeller in the housing for agitating and mixing therein material entering the housing through the respective openings.

7. In froth otation apparatus, an emulsier unit comprising a housing having top and bottom passages for admission of material under treatment thereto in opposed streams, two rotary impellers disposed in intercommunicating relation at different elevations in the housing, and a baille member enclosing each upper and lower surface of the respective impellers and having a passage for the admission of material to the im'- peller, there being a connecting passage between the adjacent baffles intermediate the two impellers, providing a zone of intermixture for the opposed streams.

8. In froth notation apparatus, an emulsiiler unit comprising a housing having top and bottom passages for admission of material under treatment thereto in opposed streams, two rotary impellers disposed in intercommunicating relation at different elevations in the housing, and

opposed baiiies covering the respective Aimpellers and having' passages for the admission of material to the impellers, there being a connecting passage between the bailies intermediate the two impellers, and the several baffles being provided with a plurality of recirculating openings.

9. In froth flotation apparatus,A an emulsifler unit comprising a housing having top and bottom passages for admission of material `under treatment thereto in opposed streams, a rotary disk impeller disposed in intercommunicating relation and a rotary dished impeller disposed in intercommunicating relation at diiierent elevations in the housing, and a baffle-member enclosing each upper and lower surface of the respective impellers and having a passage for the admission of material to the impeller, the dished impeller being located beneath the disk impeller to direct matter elevated by its dished surface `in impinging relation to matter descending from the enclosure of the disk impeller.

10. In froth notation apparatus, an emulsier unit comprising a housing having top and bottom passages for-admission of material under treatment thereto in opposed streams, two rotary impellers disposed in intercommunicating relation at diierent elevations in the housing, and a baiiiemember enclosing each upper and lower surface of the respective impellers and having a passage for the admission of material to the impeller, said baiiles terminating inspaced relation to the housing to provide passages for movement of material through the housing. p

11. In froth flotation apparatus, an emulsiermechanism comprising a rotary disk, and opposed stationary baflies covering the disk and slanting in converging relation toward its periphery, there being passages in the baiiles for admitting matter to the disk. v

12. In froth flotation apparatus, an emulsifiermechanism comprising a rotary dished impeller, and opposed stationary baiiles covering the impeller and slanting in convergingv relation toward its periphery, there being passages in the baiiies for admitting matter to the impeller.

13. In froth flotation apparatus, an emulsiflermechanism comprising a rotary impeller, and opposed stationary baiiles covering the impeller and slanting in converging relation to a peripheral termination beyond the periphery of thel irnpeller.

14. The combination with flotation apparatus, including a rotary impeller shaft and a sectional hollow column around the shaft, of an emulsifier unit, including a hollow housing or greaterv area than the column, a supporting baille-element at one of its ends, provided with an annular recessed portion adapted to seat on a section of the column, and having at its opposite end a recess providing a seat for another section of the column.

15. In froth notation apparatus, including an agitation chamber and a separation chamber interconnected for the flow of material from one to the other, an emulsifying unit in the separation chamber, comprising a housing open at its top and bottom to admit opposed streams of matter from the separation chamber and a rotary impeller for agitating and mixing the streams of material enteringthe housing, and a conduit having an inlet in the housing in a position to admit said mixture andhaving a discharge outlet in the agitation chamber for delivering said mixed matter directly into the agitation chamber.

16. In emulsifying apparatus including a tank for liquids having an overilow determining a liquid level therein, a rotary impeller beneath the liquid level, a conduit extending from above the liquid level and having an outlet above the impeller in a position to permit discharge of conducted matter onto the impeller, a cover-element for the impeller, and conductive means for gaseous fiuid having its discharge outlet extending through the cover adiacent the outlet oi the conduit and in proximity to the periphery of the impeller.

1'7. In emulsiiying apparatus including a tank for liquids having an overow determining a liquid level therein, a rotary impeller in the liquid body, an upwardly-ranging conduit in the tank having its lowermost terminus at the agitator.

a hood over the agitator outside the conduit, and

conductive means for discharging a gas under pressure through the hood onto the agitator in proximity to its periphery.

18. In emulsiiying apparatus including a tank for liquids having an overilow determining a liquid level therein, a rotary impeller beneath the liquid level. an upwardly-ranging conduit in the tank having its lowermost terminus at the agitator in a position to permit discharge oi conducted matter onto the agitator, a cover-element for the agitator, and conductive means for gaseous fluid having its discharge outlet extending through the cover-element adjacent the outlet oi the conduit and in proximity to the 'periphery of the impeller.

ARTHUR C. DAMAN.