US2074403A - Flotation apparatus - Google Patents

Description

March 23, 1937. M. KRAUT 2,074,403

FLOTATION APVP'ARATUS Filed Sept. 17, 1955 7 Sheets-sheet l INVENT OR.

MA x K RA u T ATTORNEY.

' 'March 23, 1937. M K RAUT 2,074,403

FLOTAT ION APPARATUS Filed Sept. 17, 1935 7 Sheets-Sheet 2 l 4/3 f1 n! o n .Il .43 .Il

IIII I o IN 9 o l di INV ENTOR.

MAX KRAUT ATTORNEY.

March 23, 1937. M. KRAUT 2,074,403

' FLOTATION APPARATUS v Filed sept. 17, V1955 7 sheets-sheet 5 1 INVENTOR.

MA x KRA u 1' ATTORNEY.

March 23, 1937. M. KRAUT FLOTATION APPARATUS Filed sept. 17, 1955 7 Sheets-Sheet 4 INVENTOR.

MAX KRAUT ATTORNEY.

March 239 E93?. M KRAUT 2,074,403

FLOTATION APPARATUS Filed sept. 17, 19:55 7 sheets-sheet 5 INVENTOR.

MA x KRA U T ATTORNEY` March 23, 1937.

M. KRAUT FLOTATION APPARATUS Filed Sept. 17, 1955 Hg- Z- '7 Sheets-Sheet 6 INVENTOR.

ATTORNEY.

March '23, 1937. M. KRAUT 2,074,403

FLOTATION APPARATUS Filed sept. 17, 1955 7 sheets-sheet 7,

INVENTOR.

MA x KRA u T IE'; BY

ATTORNEY.

atented s .23, 1%?

FLUTiTlIGN APPATUS Max Kraut, San Francisco, Calif., assigner to Pan-American Engineering Corporation, Ltd., Berkeley, Calif., a corporation of California Application September 17, i935, Serial No. ,40,897

lin (Canada @ctolier 1,1934

7 Ciaims.

My invention relates to an apparatus and method for the recovery o values from ore pulp, and more particularly to a notation apparatus of improved construction.

1n my prior Patent No. 1,802,919, granted April 23g, 1931 and in my prior co-pending application, Serial No. 651,175, led January li, 1933, Patent 2,0i4,250, dated June 16, 1936 are disclosed apparatus which include a stationary shell or stator?, and a rotor rotatable within the stator and forming an annular passageway therebetween through which ore pulp is caused to now at a high velocity by means of helical screw flights on the rotor. Air is induced into such passageway; 4and parts of the apparatusA are so constructed as to cause expansion of the pulp. Such expansion produces the eect of a partial vacuum to thereby Y enhance absorption of the induced air; the particles of air serving as the means for attachment tou the mineral particles to be floated from the The prior application, in addition, discloses means for squeezing the pulp during some portion of the now, to effect a dierential increase in velocity of the pulp, with respect to the mean velocity ow, to attenuate or divide the air in extremely small particles. In the machine of the present application, improved features of construction are employed to provide for expansion and squeezing of the pulp.

Objects of invention My invention has as its objects, among others, the provision of an improved apparatus, of the character related, which is (l) Of simple and economical construction;

(2) Of durable construction;

(3) .Provided with improved means to preclude piling up of sand in the pulp as the material enters into the passageway f ormed by the rotor and the stator of the apparatus; and which is (i) Provided with improved means for enhancing formation of froth on top of the pulp level in the apparatus.

Other objects of the invention will become apparent from a perusal of the following description thereof.

` General description In general, the apparatus includes a tank in which pulp (a uid mixture of water and the mineral to be treated) is fed. To the pulp may be' added any of the suitable notation reagents mown to the art, for enhancing selective separation or flotation of the desired mineral substances in the pulp. The tank may have therein a single notation cell for effecting induction of air into the pulp to provide means for attachment to the mineral particles to be oated. However, to increase the capacity of the machine. as is well (Ci. MB1-93) known in the art, the tank is of sumcient size to contain a plurality of notation cells arranged in tandem. Such arrangement is disclosed herein.

The cell unit to which my invention is primarily Vdirected comprises a cylindrical shell or stator member, and a cylindrically shaped rotor member forming an annular passageway with the stator, through which passageway the pulp flows. The rotor is rotated at a comparatively high speed, and is formed with screw nights of increasing pitch or lead all the way from the point of entrance for the pulp into thepassageway, to the point of discharge thereof from the passage- Way. Also, the rotor is hollow inside and its wall is apertured to permit air to be induced into the passageway. Because oi the increasing pitch of the screw ightsand the mechanical movement of the pulp which is effected by the screw flights as the rotor is rotated at a high velocity, expansion of the pulp occurs to produce the eiiect of a partial vacuum, to thereby enhance aerating, or absorption of the induced air in the pulp.

Adjacent the point of discharge of the aerated pulp from the annular passageway formed by the stator and the rotor, a portion of the screw flights is formed with an increased root diameter to diminish or restrict the cross-sectional size of the passageway. Hence, a relative restriction to the flow of pulp obtains at the point of discharge thereof, to exert a squeezing action on the pulp. Such squeezing action is translated into terms of increased velocity of the pulp with respect to themean velocity flow, to eiect ne division or attenuation of the induced air.

Both the stator and the rotor are formed primarily of rubber. Such material has been found to have a remarkably long life, even when the machine is handling coarse feed.

To prevent piling up of sand at the point of entrance of the pulp into the annular passageway formed between the rotor and the stator, shroud means is provided. Such shroud means is formed with ports or apertures of comparative- 'ly small size. The ports cause the pulp to flow at an increased velocity therethrough, -to minimize deposit of sand, and thereby preclude clogging of the apparatus. A conically shaped deilector is provided to direct the aerated pulp into the froth on top of the pulp level in the apparatus.

Description of drawings Reference will now be made to the drawings for a more detailed description of. invention. In the drawings:

Fig. l is a front elevation of the apparatus, showing a. plurality of cells in a single tank.

'Parts of the structure are omitted from the view t disclose more clearly the construction.

Fig. 2 is an end view looking in the direction of arrow 2 in Fig. 1.

Fig. 3 is a part vertical section and part elevation, of the cell apparatus of my invention.

Portions of the structure are omitted from the view to disclose more clearly the construction.

Fig. 4 is a fragmentary vertical sectional View, illustrating the upper portion of the cell apparatus mounting means.

Fig. 5 is a horizontal section taken in a plane indicated by line 5 5 in Fig. 3.

Fig. 6 is an enlarged fragmentary vertical sectional view, taken adjacent the pulp discharge end of the cell apparatus.

Fig. 7 is a vertical sectional view` through the rotor and the stator of the cell apparatus.

Fig. 8 is a vertical elevational view, looking at the inside of one of the plurality of like staves which form the rotor of the cell apparatus.

Figs. 9, 10, and 11, are sectional views taken, respectively, in planes indicated by the lines 9 9, Ill-I0, and H-H in Fig. 8.

Fig. 12 is a plan View of a froth expulsion ring employed in the apparatus and which is also illustrated in Figs. 3 and 6.

Detailed description With reference to Figs. 1 and 2, the apparatus including a plurality of flotation cells, comprises tank l of suitable material, preferably of welded metal plate construction having at one end thereof intake box 2 for the pulp, and at the opposite end pulp discharge box 3. An apertured partition wall 5 is provided between the various cell units C. As can be seen more clearly from Fig. 2, the bottom of tank I is formed to taper inwardly so as to provide a funnel-shaped structure for directing the pulp being treated, toward the inlets of the cell units.- Each cell unit, in a manner which will be subsequently described, aerates the pulp and discharges such aerated pulp adjacent the pulp level 6 in the tank. Aeration of pulp creates froth l over the pulp level; the froth comprising air particles to which the oated mineral particles are attached. All cells C have a common pulp level, but each cell has its own froth control lip 3 adjustable as to height by means of suitable adjusting mechanism 9. The discharged froth, as 50 can be seen most clearly from Fig. 2, ows over lip 3 into a suitable sluice box not shown.

For adjusting the pulp level of the apparatus,

an adjustable Weir gate il is provided in dis- 65 the pulp is caused to discharge from vthe apparatus in a tortuous path to enhance separation of sand therefrom.

In operation of the apparatus having a plurality of cells, the pulp enters near the bottom A70 of the first cell, and is advanced by displacement from cell to cell until it reaches the discharge end of the apparatus. The apparatus may, of course, comprise only a single cell, but it is customary to employ a battery of cells to increase the capacity. 75 Each cell includes a part to be rotated. as will be subsequently described. For driving such parts, an electric motor I8 is mounted oithe apparatus; its drive shaft I9 being connected by belts 2l to the rotatable parts of the individual cells.

Referring particularly to Figs. 1, 3, 4, 6, 7 and 8, it will be observed that the cell unit comprises stationary tapered shroud 22 secured to the bottom of tank l, and to which is secured cylindrically-shaped rubber covered stator or Shell 23, 10 by means of clamps 25. Rotatable within the stator is hollow rubber covered rotor 26, having thereon screw flights 21. Such rotor is secured for rotation with rotatable hollow shaft 28, and is formed of a plurality of individual rubber covl5 ered staves 29 (Figs. 3 and 8). The staves are spaced apart to provide slots 3l for admission of air into annular passageway 32 formed between the stator and the rotor. A stationary conicallyshaped rubber covered deector 33 having its 20 discharge lip extending below pulp level 6 (Fig. l), is positioned over the top of the stator, It will be noted that in each of the stator, the`rotor staves and the deflector has, respectively, metal reeniorcing plates 3ft, 36 and 37 to which the 25 rubber of these parts is vulcanized.

Mounting means for the rotor parts, the rotatable hollow shaft and the stationary defietor are provided. Such mounting means, and `also mechanism associated with the mounting means 30 will now be described. Hollow shaft 28 extends, at its upper end, into ystationary housing member [i5 (Figs.`2 and 4), having secured thereto adjustable air inlet control valve 6i; suitable packing i2 being provided between stationary mem- 35 ber li and rotatable shaft 28. Pulley 133,#xedly secured to shaft 28, is driven from belt 2l in the manner previously related.

The hub of pulley 63 rests on thrust collar lli keyed to shaft 28. Collar Lili in turn bems 40 against the inner race of bearing Q5; the outer race of such bearing seating on flange lll of upper bracket 38 which is secured to the frarne of the apparatus and has tubular depending portion i9 (Fig. 4). The inner race of bearingii 45 rests on grease slinger of usual construction; within which is positioned grease guard ring 5l. Grease slinger 50 rests upon -spacing sleeve 52 which is clamped for rotation with shaft 23, bev tween grease slinger 53 and the inner race of 50 bearing 53 (Fig. 6). Such bearing is supported by shoulder 55 formed on the shaft.

With reference to Figs. 3 and 6, it will be ob 4 served that spacing sleeve 52 extends throughn lower bracket 5l fixedly mounted on the frame 55 of the machine. Such lower bracket provides the support for conical delector 33 and related parts. As can be seen from Fig. 1, bracket 5l has an upwardly extending tubular portion 53 secured to the depending portion 49 of upper 60 bracket 33 to provide for strength of construction. To the lower end of bracket 5l (Fig. 6), is removably secured annular plate 59 having therein split ring 3| for retaining suitable packing 62. A grease guard ring 63 is also supported 66 on plate 59.

Upper flange 66 of bracket 51 has removably secured thereto channel-shaped ring 56; and to the lower end of ring 36 is removably secured the stationary conically-shaped deector 33. The inner side of such deector has a plurality of peripherally-spaced ns or baiiles 3l mounted thereon. Lower ange 68 of bracket 5l provides a support for stationary plate 69 having its under surface covered with rubber and formed with an aovaaos annular channel 'il adapted to co-operate with rotatable rubber covered froth expulsion ring l2 having reenforcing plate 13 secured to stave supporting member 'M in turn xedly attached to shaft 2d. The upper ends of rotor staves 29 are secured to member lt. Hence, the rotor formed of such staves is secured for rotation with hollow shaft 2t.

From Fig. 12, it will be observed that froth expulsion ring i2 is formed with a plurality of tangentially arranged slots' l5. Such slots in conjunction with the co-operating bevelled outer edges 'Il of rubber covered-member @t and ring l2, and upstanding portions 'it rotatable in annular channel ll, serve eectively to prevent iroth from creeping past ring l2. Hence, means is provided to prevent froth from piling up or collecting too high under deector 3ft.

To the lower end of hollow shaft 2t (Fig. '7) is secured a collar member 8l, to which the lower ends of the rotor staves are secured by means of studs d2. For the purpose of protecting studs t2 against abrasion by material iiowing into the cell, a rubber cover t3 is provided- Such cover is clamped between the lower edge of collar member ti and a flange it formed at the lower end of a rubber ring tt held between member tl and the inner side of the rotor.. the rotor staves are fastened to reenforcing ring tl through which shaft 2t passes.

is canl be seen from Fig. 7, apertures tt are formed in shaft 2t to provide for iiow oi induced air from the shaft through the slots ill (Fig. 3) of the rotor and into the annular passageway 32 formed between the stator and the rotor. Shroud 22 is formed with ports or apertures @t to provide for flow of pulp into the cell. Such apertures t@ are formed by rubber rings 9i removably held on the shroud. I'he rings being ci rubber withstand effectively the abrasive action caused by the iiowing pulp. Furthermore, since the rubber rings are removably mounted, they can be readily i replaced vto provide for apertures of selected size to control the velocity flow of pulp into the cell.

Figs. 3, 5, 8, 9, 10 and l1 illustrate the construction of the rotor, and the rotor staves 2d. It will be noted that adjacent their lower edge portions at h2, the construction of the staves is such as to provide for edge to edge contact of the staves upon assembly thereof. Above such edge portions 92, the stave edges are cut away at `llt to provide the apertures or slots di in the assembled rotor. At the top, the staves have edge portions ad adapted for edgeto edge contact.

Rubber screw ight portions 2l' of the individu.

al staves, are of such character, as to provide screw `ights oi increasing pitch or lead all the way from the inlet of annular passageway t2 to the outlet thereofat the top, as can be observed from Fig. 3. Since the staves form a substantially cylindrically-shaped rotor, the external diameters of the screw ights is substantially the same throughout. Consequently, and because of the increasing lead or pitch of the screw flights, the volume dened by the grooves or spaces between the helical screw ights or ribs, progressively increases from the inlet to the outlet of the passageway 32.

Adjacent the outlet for pulp from passageway 32, it will be observed, as can be seen most clearly from Figs. and 10, that the rotor staves have portions 96 of increased roo't diameter, compared to the constant root diameter of the staves below such portions. Consequently, adjacent the outlet or discharge end of the pulp trom passage- Intermediate their ends,-

way 32, the passageway is of decreased cross-sectional size to oiler a restriction to the ow of pulp to thereby eiect a dierential increase in velocity thereof. At such outlet of pulp from passageway 32, the screw flights terminate in flange portions @l extending substantially longitudinally with respect to the axis of the rotor to eflect tangential throw-od of the pulp and thereby facilitate, by the action oi centrifugal force, discharge of the pulp against bailles 31 on the conically-shaped detlector 33.

In operation. the pulp to be aerated enters the inlet of annular passageway 32 after having passed through the ports or apertures il@ of shroud 22. Because of ported shroud 22, the pulp has a comparatively high velocity flow, caused by rotation of the rotor, prior to entering the inlet of passageway 32. As a result, sand. slag and other heavy foreign substances are prevented from piling up at the inlet of passageway 32 to thereby preclude clogging of such passageway, which might otherwise occur. Since ports t9 are adjustable as to size by virtue of the removable rubber rings 9i, it is apparent that the velocity flow through the ports can be controlled by preselection. l l

The high speed of rotation of the rotor, which may be as high as 1000 R. P. M. or even higher, depending upon the character of material being treated, causes the helical screw flights 2l thereon to elevate the pulp mechanically at high velocity; the pulp being dischargedover the outlet opening adjacent the upper edgelof the stator 23. During such elevation of the pulp at a high velocity, the air passing from within the rotor through its apertures formed by slots 3l, is subjected to outward forces created by centrifugal action; and the high velocity iiow of the pulp creates an aspirator effect. These two actions together cause induction of air into the pulp, through the rotor slots to thereby effect aeration of the pulp.

Because of the progressive increase in volume caused by the increase in pitch or lead of the screw flights all the way from the inlet to the outlet of the annular pulp aeration passageway 32, the pulp is expanded as it is mechanically elevated, to thereby produce an eiect equivalent to that of a partial vacuum. As a result, absorption of the induced air is enhanced to provide for efdcacious aeration. In this connection, it will be noted that the substantially cylindrical stator 2t, the substantially cylindricallyshaped rotor 2t, and the screw iiights of gradiently increasing pitch, provide an economical to manufacture construction for creating expansion of the pulp, as such parts lend themselves to ready production.

As was previously related, the increased root diameter of the rotor adjacent the outlet of passageway 32, restricts the cross-sectional size oi. the passageway at this point. Hence, at the location of discharge of the pulp from passageway 32, there is provided a restriction to the how of pulp resulting in a squeezing action on the pulp. Such squeezing action eiects, with respect to the mean velocity how of the pulp, a differential increase in velocity. This results in fine division or attennation of the air induced into the pulp, to provide a large number of fine air particles for attachment to the mineral particles to be floated.V

Such squeezing action does not cause the pulp to ow inwardly through the rotor slots 3l because the outward forces created by centrifugal action of the rotor as the pulp is mechanically elevated a hi velocity 4g: positive rotation of the screw flights on the rotor, are greater than the forces created by the squeezing action. It is thus` seen that the improved machine of the present application has means for squeezing the pulp, as well as means for expanding it, as is generically disclosed in my copending application to which reference has been made.

The pulp is tangentially discharged by means of the axially extending portions ill of the screw ights, and it, consequently, strikes against the radial bales 6l on conical dei'lector 33. Such baiiles break up whirling, so that the froth may rise gently above the pulp level without breaking up of the air particles or bubbles to which the l5 mineral particles are attached. In this connection, the conical or outwardly tapered shape of the hood or deilector 33, the lower edge of which extends below the pulp level 6, as can be seen in Fig. 1, serves to direct the material more or less tangentially into the froth, minimizing breakage of the air bubbles or particles, which might occur with a cylindrically-shaped deflector.

I claim:

l. A flotation apparatus comprising a cylindrical stator, a cylindrically-shaped rotor rotatable within said stator and forming an annular passageway therebetween, said passageway having an inlet and an outlet for the iiow of pulp, screw flights on said rotor of increasing pitch from adjacent said inlet to adjacent said outlet, a

ported shroud adjacent said inlet, and a conicallyshaped deflector adjacent said outlet.

2. In a notation apparatus, a rotor formed of a plurality of staves spaced apart to provide slots 35, therebetween, and helical screw ghts formed on the staves, said screw nights having a continuous increasing pitch.

3. A flotation apparatus comprising a cylindrically shaped stator, a cylindrically shaped rotor dening an annular passageway therebetween, said passageway having an inlet and an outlet for the flow of pulp, means for introducing air into said rotor, said rotor being apertured to allow admission of air into said passageway, and means to eiect expansion of said pulp to enhance aeration thereof including screw ights on said rotor extending all the way from adjacent said inlet to adjacent said outlet and of increasing pitch from adjacent said inlet to adjacent said outlet.

4. A iiotation apparatus comprising a cylindrically shaped stator, a cylindrically shaped rotor defining an annular passageway therebetween, said passageway having an inlet and an outlet for the iiow of pulp, means for introducing air into said rotor, said rotor being apertured to allow admission of air into said passageway, and means to eect expansion of said pulp to enhance aeration thereof including screw ights on said rotor extending all the way from adjacent said inlet to adjacent said outlet and of increasing pitch from adjacent said inlet to adjacent said outlet, the external diameter of said/screw ights being substantially the same thrughout, and the wall of said rotor adjacent said outlet being of increased root diameter to provide a restriction to the flow of pulp adjacent said outlet.

5. A flotation apparatus comprising a chamber adapted to contain pulp, a cylindrically shaped stator in said chamber, a cylindrically shaped rotor in said chamber and defining an annular passageway with said stator, said passageway providing at one end thereof an inlet for pulp contained in said chamber and at the opposite end thereof an outlet for said pulp, means including a hollow shaft extending into said rotor for introducing air, said rotor being apertured to allow admission of air into said passageway, and means to effect expansion of said pulp to enhance aeration thereof including screw ights on said rotor extending all the way from adjacent said inlet to adjacent said outlet and of increasing pitch from adjacent said inlet to adjacent said outlet.

6. A flotation apparatus comprising a chamber adapted to contain pulp, a cylindrically shaped stator in said chamber, a cylindrically shaped rotor in said chamber and defining an annular passageway with said stator, said passageway providing at one end thereof an inlet for pulp contained in said chamber and at the opposite end thereof an outlet for said pulp, means including a hollow shaft extending into said rotor for introducing air, said rotor being apertured to allow admission of air into said passageway, means to eect expansion of said pulp to enhance aeration thereof including screw iiights on said rotor extending all the way from adjacent said inlet to adjacent said outlet and of increasing the pitch from adjacent said inlet to adjacent said outlet, and a conically shaped pulp deflector over said outlet.

'7. A flotation apparatus comprising a chamber adapted to contain pulp, a cylindrically shaped stator in said chamber, a cylindrically shaped rotor in said chamber and delning an annular passageway with said stator, said passageway providing at one end thereof an inlet for pulp contained in said chamber and at the opposite end thereof an outlet for Said pulp, means including a hollow shaft extending into said rotor for introducing air, said rotor being apertured i a ported shroud for precluding piling up of sand contained in said pulp.

, MAX UT.

Images