US2246560A - Flotation machine - Google Patents

Description

June 24, 1941. wElNlG ETAL 2,246,560

FLOTATION MACHINE Filed Aug. 1, 1939 3 Sheets-Sheet l T u 5 T- g, 8 K a 1; l \zgfijfi by a. W M m zl {it a I? I /a 16 Fri -I9a 221519 iii Fig.1. 14

I N VEN TORS ARTHUR J. Wis/-10 AND RODERICK D; RENNER June 24, 1941- A. J. WEINIG ET AL FLO'I'ATION MACHINE Filed Aug. 1. 19:59

3 Sheets-Sheet 2 INVENTORJ g ARTHUR J WEI/we AND BY RODfR/CK 0. Rams/e ATTO EY5 June A. J. WEINIG ETAL. 34 .5 0

FLOTATION MACHINE Filed Aug. 1, 1939 3 Sheets-Shoat 3 ARTHUR J. Wc/ma AND Rona-men D. RENNER into the cell and terminate in nozzles 22 extend-' ing into a central opening l9a in theupper portion or the impeller l9. Gas under pressure is delivered to the impeller through the header 20 and conduits 2| and the volume of gas so admitted is controlled through the medium of valves 23.

Some operations will necessitate the introduction of reagent directly into the cell in preference to a preliminary conditioning treatment and the agitating and aerating influences of the machine are utilized for mixing the reagent. To this end, a reagent feeder is incorporated in the cell structure and comprises a funnel 26 located above the overflow level of the cell and a conduit 28 extending from the funnel into the. opening tile and t ninating in a discharge outlet located in proximity to the discharge nozzles 22.

The impeller it of the present invention has top and bottom plates itlb and itc respectively, which are separated by a dividing member or partition 6% extending from a hub member ile approximately midway between the top and bottom plates.

The dividing member ltd is provided with a central opening 991a adjacent the hub Ste, and this arrangement permits a. portion of the pulp entering the impeller through the opening Hits to pass below the dividing member into the lowermost discharge compartment B, while the remaining pulp entering through opening i911 passes through the upper compartment A to the peripheral discharge.

In order to maintain a balanced relation in the distribution of feed entering through open- I central openings i911 and E912, the gas discharge 4 nozzles 22 terminate adjacent the dividing member 88d between the opening i912 and the peripher? of the impeller. By this arrangement, little, it any, of the discharging gas is drawn into the pulp stream entering compartment B and while some slight amount of gas may be present in the recirculating pulp by reason of previous entrainment, the volume of pulp traveling through compartment B will contain at most only minor quantities of undissolved gas.

As a consequence, the streams in the upper and lower chambers closely correspond'in composition with the corresponding streams described in the aforesaid Weinlg application.

In order to insure proper movement of the material through the compartments A and B, vanes I971. are provided which exert an impelling action on the material delivered to these compartments and force a rapid movement thereof toward t periphery.

In such impelling action, the vanes lilh produce a substantial mixing action as an incident to the impelling movement, with the result that the streams brought into intermixture at the periphery have already undergone an appreciable degree of mixing before impinging and penetrating the static body of pulp beyond the impeller.

As this form of impeller does not utilize a suction action to draw material upwardly from the bottom of the tank into the impeller, it is advisable to provide the undersurface of the impeller with sweeping vanes l 9m which pump material in through inlet l4 and move any solids tending to collect on the bottom of the tank outwardly toward the walls of the cell where the full force of the agitative action and peripheral ejection acts thereon to move the settled constituents into suspension.

As illustrated in Figure l, the pulp entering through inlet M is caused to travel laterally along the bottom of the tank underneath the impeller, and beyond the periphery rises under the influence of the agitation, with a portion thereof recirculating back through the opening 89a of the impeller. In the impeller, the entering pulp divides into two streams of different volume. The stream of lesser volume passes down into compartment B and is caused to travel by the impelling influences under the centrifugal influence to a point of discharge at the periphery. The stream of larger volume enters compartment A and upon entrance is subjected to the mixing influence of gas under pressure discharged through nozzle 22.

Where reagent is introduced directly into the cell, the reagent discharge is preferably located as illustrated in Figure 2, with the conduit 25 terminating near the opening Mn and somewhat above the same. The separation and diiferential movement of the two streams occur adjacent the discharge end of conduit 25 with the result that some of the reagent passes with the stream entering compartment B, while the remainder is entrapped in the stream moving through compartment A and in the mixing action in such compartments is brought into thorough and intimate contact with the solid constituents of the pulp therein.

From the foregoing, it will be apparent that compartment B will operate in an underloaded condition as the opening its is not large enough to satisfy the volume requirements thereof, while compartment A, due to the greater diameter of the opening lea under the influence of a hydrostatic pressure in thetank, operates lnan overloaded condition. This results in the formation of a partial vacuum in compartment B, which at the periphery is satisfied by the downward flow of pulp from compartment A, due to the excess pressure thereof.

The resulting impingement oi the two sqeams causes the gas, solids and liquid, inclusive of reagent, to be brought into thorough and intimate intermixture which is further intensified and developed by reason 01 the resistance offered by the more or 1653 static body of pulp beyond the periphery to the discharging intermixture.

Thereafter, the impelling force of the agitation and aeration causes the pulp stream to ascend in the tank along theconfinlng walls thereof and the entrapments oi the flotation reaction rise freely in this ascending column without impedance from material above. Matter held only in suspension and heavy enough estates to separate from the pulp stream in its upper portion is drawn toward the central portion the cell in which there is a descending column of liquid, due to the pumping action of the impeller and the provision of the central opening I941.

As a consequence, solids separating out of suspension pass into the central zone of descent before returning to the agitation zone under gravitational influence, and this withdrawal of settling solids from the rising column prevents any impedance thereby which might serve to rupture the surface attachments of the bubbles in the flotation reaction.

The material carried to the surface under the aerating influences becomes entrapped in the froth and moves across the overflow lip l as a concentrate.

The form of the invention illustrated in Fi ures 3 and 4 is similar to that previously described, with the exception that the flotation cell in this form of invention has its feed inlet at some location other than the bottom, and as a consequence, the impeller preferably is located at some distance from the bottom to provide a larger zone of non-aerated liquid in the bottom oi the tanlr, which in part is recirculated in its elevatine movement by the asitation oi the inipeller through the opening its and back into the impeller for further treatment.

in the cell illustrated in Figure 3, the inlet and discharge control have not been illustrated, but since such cells are in general use and welllrnown in the art, the details of such control appear unnecessary. It will be understood that some provision will be made ior regulating the iiduicl level in the cell and thereby control the depth oi iroth which passes over the overflow lip it.

in each term of the invention illustrated, the iiotation action is the same and the circulatory movement determined by the impeller is likewise is the same in each of these cells. While the tunnel 24 and associated conduit have only been shown as applied to the form of cell illustrated in Figure 1, it will be understood that such structure may be employed in either form at :cell wherever required.

linthis connection, the feature oi the previously identified Weinig application in utilizind means of restraining any vortex tendencies at the impeller inlet 19a is also utilized in the present invention. i

The form oi! the invention illustrated in Figure 5 illustrates another modification of the invention, which is productive of highlybeneflcial results in certain types of treatments. The cell of this form oi the invention is substantially the same as the type illustrated in Figure l, with feed to the cell provided by the inlet H at the bottom thereof. The grid element ll preferably is omitted and a column 21 encloses shaft I8 and the pipes II and 25. i This column has its lower terminus in close proximity to the top of impeller l9 and is of a diameter large enough to encompass the opening Isa into the upper portion of the impeller.

The upper end of column 21 terminates below the froth bed of the cell determined by'overflow l5, a'nd in the preferred form, a slidable collar 28 is mounted at the upper endof column 21 i to vary'the effective elevation thereof.

suitable manner, it has been found convenient to mount it on the bafile structure 9 either by frictional engagement therewith or through the intermediary of any suitable fastening device and thus insure its maintenance during operation in close proximity to the impellerit but out of frictional engagement therewith.

The provision of the column serves to aiford a closer control of the circulatory movement and restrains any tendency toward cross currents within the liquid body, which might otherwise serve to co-mingle the ascending and descending streams.

It is intended that the descending stream of material in this form of the invention should not return valuable constituents responding to the flotation action, but only so much of the mineral content as is being maintained in a state of suspension below the froth bed and is not being carried into the froth by the flotation reaction.

The enclosure thus provided for the impeller inlet Illa is subjected to a strong pumping influence induced by the impeller, and it the enclosure is extended into close proximity to the ii'roth bed, a. vortex action will result which will dil the ass conduits 2i and reagent conduit 2% as a prove the metallurgical result.

' The form of cell illustrated in Figure 6 is similar to that illustrated in Figure 3 and has associated therewith a column 21a provided with a draw down portions of the concentrate. Therefore, the provision of the collar it is oi importance in providing tor selective variation in the elevation of the conduit, to eliminate vorteir tendencies and provide a means for density regulation in the upper portion oi the pulp body. The pipes ti and it serve to restrain any vorteit tendencies at the upper end of column ill and by proper location oi the collar it, vorteii conditions can be eiiectively eliminated.

in the upper portion of the pulp body immediately below the froth bed, there will be a zone containing a relatively large percentage of mineral which has been partially and incom pletely elevated by the flotation action and supplemented by the suspending tendencies oi the agitation, which as the operation proceeds, will increase in density.

This zone or increased density impedesto some extent the emcient performance of the flotation reaction in that minerals ascending under the action of the gas will not freely penetrate such zone and carry into the froth, and while some oi the mineral in the zone is further elevated by the penetration of the gas into the zone, much of the mineral content is not carried into the froth and consequently passes to the nest treatment stage with the tailing rather than the concentrate.

By locating the top of the column at or near such zone, the suction influences of the impeller serve to draw in large quantities of such mineral content and return the same to the impeller for retreatment and subsequent elevation into the froth. As a consequence, in certain treatments,

such as the flotation of ores carrying relatively large quantities of middlings product which are imperfectly floated by the normal action, the provision of the column 21 in the cell serves to imcollar 28 for varying its effective elevation. This column 21a is of a diameter less than the diameeter of the opening lfla into the impeller and is mounted in the cell with its'lower terminus in compartment A of impeller i9.

- With this form of column, a portion of the impeller discharge recirculates back through the opening l9a without rising into the upper portions of the cell and there mixes with pulp delivered through column 21a into compartment A and after being subjected to the aerating influences, is again ejected from the impeller in the manner heretofore described.

From the foregoing, it will be apparent that the feed supplied to the impeller throughthe columns 21 and 21a is split and distributed between the compartments A and B as in the other forms of the invention, and the treatment of the material within the impeller is, in all essential respects, the same as hereinbefore described.

It is also obvious to those skilled in the art that either form of column 21 or 210 may be applied to any of the various forms bl cell construction here illustrated, and the application of the respective forms to the various cells in the drawings'is intended only as illustrative and not as being limited to such forms.

While in the forms illustrated herein-the dividing member 19d is shown as'being of the same diameter as the'top and bottom plates lfib and E90 respectively, it will be appreciated that whenever desired for any reason, the dividing member may he of a lesser diameter to induce a lore; liminary mixing within the confines oi the impeller before discharge of the material across the periphery.

likewise the size of the vanes 89?; may be varied, and while the arrangement illustrated is the preferred form, it is within contemplation of the invention that vanes of diiierent sizes may be variably located within the passages A and B,

and in fact, any vanes which serve to exert an impelling action on matterin the passages may be substituted for those illpstrated herein.

The explanation of the relative diameters of the openings its and i9 demonstrates the of fectiveness of therelationship in controlling the amount of material delivered to each of the possages A and B. and it will be understood that variations. inthe size of such openings may be resorted to to obtain different degrees of mixing and discharge. v 7

Changes and modifications may be availed oi within the spirit and scope of the hereunto appended claims.

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

1. In separating apparatus, a rotary mixing element comprising upper and lower chambers, separately open at the periphery of the element for the separate discharge of two currents of pulp into a mixing zone exteriorly of said periphery, both chambers having central openings in their upper surfaces to receive pulp in which the element is immersed with one of said openings in their upper surfaces of greater diameter than the other, means for introducing gas in excess of atmospheric pressure into the pulp at the central opening oi greater diameter, and vanes in the chambers to accelerate outward movement of pulp through the peripheral openings thereof.

2. In separating apparatus, a rotary mixing element comprising upper and lower. chambers. separately mm at the periphery of the element for thefseparate-discharge of two currents of pulp into amixing zone exteriorly of said periphery, both chambers having central openings in their upper surfaces to receive pulp in which the element; is immersed with the opening oi. the upper chamber of greater diameter than the opening of the lew er chamber, means for intro-- ducing gas-in excess of atmospheric pressure into the pulp at the central opening of the upper chamber and between the central opening or the lower chamber and its periphery, and vanes in the lower chamber to accelerate outward movement of pulp through the peripheral opening rotation for admission of pulp, a dividing membe; in the body defining upper and lower chambers therein, and having a central opening for admission of pulp to the lower chamber, means for introducing gas under pressure into pulp entering the upper chamber through the top openlng, andvanes in the lower chamber for impellent action on the pulp admitted thereto.

4. In aerating apparatus, a rotary hollow body having in its top an opening around its axis of notation for admission of pulp, a dividing member in the body defining upper and lower chambers therein, and having a central opening of lesser diameter than the diameter of the top opening, means in the upper chamber at a side of the'opening to the lower chamber for introducing gas under pressure into pulp entering the upper chamber through the top opening, and vanes in the lower chamber for lmpellent action on the pulp admitted thereto. 5. In separating apparatus, a rotary mixing element comprising upper and lower chambers, separately open at the periphery of the element for the separate discharge" of two "currents of pulp into a mixing "zone exteriorly of said periphery, both chambers having upper central omnings to receive pulp inwhich the element is immersed, means emendlng into the upper chamber through itscentral. opening for introducing gas in excess oi atmospheric pressure into the pulp entering therein, and vanes in the lower chamber to accelerate outward'movement of pulp through the peripheral opening thereof.

6. In aerating apparatus, a rotary hollow body having in its top an opening around its axis of rotation for admission of pulp, a dividing mom ber in the-body defining upper and lower chamhers therein, and having a central opening of lesser diameter than the diameter of the top opening means in the upper chamber for introduclng gas under pressure into the pulp in the upper chamber entering therein through the top opening, vanes in the lower chamber for impellent action on the pulp admitted thereto, and vanes on the underside of the impeller for exerting an lmpellent movement on matter exterlorly thereof.

'7. Froth flotation apparatus, comprising a tank having a feed inlet and a discharge outlet determining a liquid level therein, a rotary impeller in the lower portion of the tank having upper and lower chambers provided with a central opening for the admimion of pulp under hydrostatic pressure, means for supplying gas under pressure to said chambers through the central opening of the upper chamber, and a conduit having its inlet in the pulp body'below the froth bed determined by the overflow and'positloned to discharge into the central opening of the impeller.

8. Froth flotation apparatus. comprising a tank having a feed inlet and a discharge outlet determining a liquid level therein, arotary impeller in the lower portion of the tank having upper and lower chambers provided with a central opening for the admission of pulp under hydrostatic pressure, means for supplying gas under pressure to said chambers through the central opening of the upper chamber, and a-conduit having its inlet in the pulp body below the froth bed determined by the overflow and terminating above and in close proximity to the impeller in encompassing relation to its central opening.

9. Froth flotation apparatus, comprising a tank having a feed inlet and a discharge outlet determining a liquid level therein, a rotary impeller in the lower portion of the tank having upper and lower chambers provided with a central opening for the admission of pulp under hydrostatic pressure, means for supplying gas under pressure to said chambers through the central opening of the upper chamber, and a conduit having its inlet in the pulp body below the froth bed determined by the overflow and extending into the impeller through the central opening thereof.

10. In aerating apparatus, a rotary hollow body having in its top an opening around its axis of rotation for admission of pulp,-a dividing member in the body defining upper and lower chambers therein, and having a central opening for admission of pulp to the lower chamber, means for in-- troducing gas under pressure into pulp entering the upper chamber through the top opening, and vanes in each of said chambers for impellent 80'.- tion on the pulp admitted thereto.

11. Froth flotation apparatus comprising a tank having a feed inlet and a discharge outlet determining a liquid level therein, a rotary im peller in the lower portion of the tank disposed to direct pulp upwardly along upright walls of the tank by its centrifugal action, a member dividing the impeller into superposed compartments, each having a central intake opening in its upper surface and a peripheral discharge outlet, means for introducing gas under pressure into the uppermost compartment of the impeller, andiconductive means disposed in the tank in a position to collect a middlings product below the liquid level and return such product through the central impeller openings for additional aeration within the confines of the impeller.

12. Froth flotation apparatus comprising a tank having a feed inlet and a discharge outlet determining a liquid level therein, a rotary impeller in the lower portion of the tank disposed to direct pulp upwardly along upright walls of the tank by its centrifugal action, a member dividing the impeller into superposed compartments, each having a central intake opening in its upper surface and a peripheral discharge outlet, means for introducing gas under pressure intothe uppermost compartment of the impeller, means for delivering flotation reagent adjacent the intake of each of said compartments, and conductive means disposed in the tank in a position to collect a middlings product below the liquid level and return such product through the central impeller openings for additional aeration within the confines of the impeller.

13. In aerating apparatus, a rotary hollow body having in its top an opening around its axis of rotation for admission of pulp, a dividingmember in the body of lesser diameter than the body defining upper and lower chambers therein, and having a central opening for admission of pulp to the lower chamber, means for introducing gas under pressure into pulp entering the upper chamber through the top opening, and vanes in the lower chamber for impellent action on the pulp admitted thereto.

14. In aerating apparatus. a rotary hollow body having in its top an opening around its axis of rotation for admission of pulp, a dividing member in the body defining upper and lower chambers therein and having a central opening for admission of pulp to the lower chamber, means for introducing gas under pressure into pulp entering the upper chamber through the top opening, and conductive means for reagent introduction having a discharge outlet terminating within the impeller and above the central opening of the dividing member.

15. In aerating apparatus, a rotary hollow body having in its top an opening around its axis of rotation for admission of pulp, a dividing member in the body defining upper and lower chambei's therein, and having a central opening for admission of pulp to the lower chamber, means for introducing gas under pressure into pulp entering the upper chamber through the top opening, and conductive means for reagent introduction having a discharge outlet terminating within the impeller and above and adjacent the periphery of the central opening of the dividing member.

ARTHUR J. WEINIG.

RODERICK D. RENN'ER.

Images