US2252576A - Flotation apparatus - Google Patents

Description

Aug. 12, 19,41. J. c; MaclN-rosH FLoTATIoN APPARATUS Filed Dec. 5l, 1938 v2 Sheets-Sheet l ulllllll Aug. 12, 1941A, J, c, NlaenqTQggl-iA 2,252,576

FLoTATIoN APPARATUS Filed Dc. 31, 1938 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patentecll'yAug. 12, 1941 l I l UNITED` STATES PATENT OFFICE FLoTA'rloN APPARATUS g John C. MacIntosh, Douglas, Ariz., assignor to Phelps Dodge Corporation, New York, N. Y., a corporation of New York Application December 31, 1938, Serial No. 248,824

9 Claims. (Cl. 209 168) This invention relates to the concentrating of end walls 2, 3 and side walls 4, 5. The pulp is mineral values from ores or other substances by introduced into the cell, from a suitable conduit `the so-called flotation process, wherein a pulp 6, through an opening 1 (Fig. 3) in the wall 2.

containing said ores or other substances, together The tailing discharges through an opening 8 in with flotation re-agents, is subjected to aeration .5 the end wall 3 into a vertical passageway 9, and agitation to produce a value-containing thence over an adjustable Weir I0 of known type, froth, thereby separating said values from the into a passage II, and then out through discharge barren or rocky materials, known as gangue. An -conduit I2. By adjustment of the weir III in the object of the invention is the provision of a novel usual way the pulp level may be regulated as ilotation apparatus whereby improved separal desired.

tion of the mineral values from gangue is at- Extending across thecell between end walls 2 tained, and high grade concentrates are proand 3, are a plurality of baffle plates which divide duced with marked elciency. Another object is the cell into compartments. Two of'these plates, to provideA an apparatus whereby the roughing designated i3 and I4 respectively, converge downand cleaning of the concentrate are accomplished .,l Wardly as shown in Figure 5. Above said plates in one unit,` as distinguished from prior practice I 3, I4 are upwardly converging baiiies I5, IB, wherein only rough concentrates are produced in respectively, each of which may, as shown, comone unit and are then transferred to a separate prise a plurality of plates, I5', l5", and IB', I6" apparatus for cleaning. In attaining these obrespectively. One .or more of the various baille jects the invention provides a new and improved plates may be Derf0r&led'es indicated et llcontrol over the introduction of air into the .pulp The baiiles may be supported in the cell in any lenclosing cell or chamber comprising a bottom i,

as a result of which the air is distributed suitable manner. For example, the ends of the throughout the pulp with particular thoroughness plate i 3, may engage in grooves i8 in the respecand effectiveness; and a novel yarrangement of tive end walls 2, 3, while similarly the ends of baiiies contributing to the production of clean plate I4 may engage in grooves I9 in said walls.'

tailings and high grade concentrates. The appa- Said grooves extend to the tops of said walls, to ratus provided by the invention is furthermore enable' Said plates t0 be Conveniently insertedsimple in construction, requires little power for The baille plates I5 likewise may engage at their its operation, and is inexpensive in upkeep. Furends in grooves 20, and the plates of baille It'in ther features and advantages of the invention grooves 2l. will be hereinafter described and claimed. A hollow shaft 22 is lurrlaleel in Suitable bear- In the accompanying drawings; ings, such as 23, 2d, on cross bars 2li. 2t, whiclrin Fig. 1 is a view in side elevation of anepf turn are supported by standards 2l. te at oppoparatus constructed in accordance with the in- Site ends 0i the Cell- Seid Shaft iS adapted te vention. ,35 be rotated from a suitable power source in. any Fig. 2 is a view partly in plan and partly in convenient manner, as by pulley 2t, shaft 30D, and horizontal section, taken on line 2 2 of Fig. l. bevel gears 3l, 32- The Upper end 0f Shaft l@ eX- Fig. 3 is a vertical sectional detail view, on an tends into stuiling hOX 33. and receives air under enlarged seele, taken en line 3 3 or Fig. 2. pressure from pipe 3e A valve 3e in said pipe Fig. 4 is a vertical sectional view, on an en- A0 may be Operated t0 regulate the Supply 0f all to larged scale, taken on line fl-li of Fig. 2.k said shaft. 2

Fig. 5 isa vertical sectional view, on an en- At its lower end the hollow shaft 22 carries a larged scale, taken on line 5 5 of Fig. 1. 'y rotor, lor agitator 36 comprising a hollow cylin- Fig; 6 is a detail View, partly in plan and partly drical body 3l having a bOlliOm 33 01 DOI'OIIS mein horizontal section, showing the agitator and-l5 teriel Such aS Perforated rubber Canvas, Woven taken on line 6 6 of Figure 5. wire cloth, or the like. Wings 39, extending radi- Fig, 'I is a bottom plan view of the agitator. ally from the periphery of the rotor body 3l, may Fig. 8 is an enlarged sectional detail view of be provided, if desired, to assist in the agitating the agitator, taken on line -t of Fig. 6. 0f the pulp. Scraper blades 40 are shown se Figl 9 is a View, partly in vertical Section and o cured to the rotor below the porous element 3e. partly in elevation illustrating an alternative In OperalOn. the Pulp 1S fed into the cell meansfor introducing air to the shaft of the through the channel t and opening l. the pulp rotor or agitator, level being determined by the height of the weir Referring to the drawings, there isshown an Iii over which the tailings DeSS intO the diS- 15 charge channel I2. Therotor or agitator 3e is supplied to said rotor by the shaft 22 passes through the bottom of said rotor and thence outwardly and upwardly through the pulp. It will be noted that the air does not pass through the side walls of the rotor and that instead it must escape through the porous medium 38. The location of said porous medium at the bottom of the rotor provides for the escape of the air against a constant static head of the pulp, and hence for its even distribution through the pulp, as distinguished from the passage of the air against variable heads in prior constructions wherein the air passes through the vertical faces of the rotor with consequent uneven escape of air into the pulp. At the same time the porous medium 38 breaks the air up into fine streams, augmenting its effective distribution. The centrifugal force incident to the rotation of the rotor furthermore imparts an outward throw to the air emerging through said porous medium, and this is accentuated by the action of the rotating scraper blades 40 against said air.

As a result of the foregoing, the air is broken up into minute streams which are so impelled as to be distributed thoroughly through the pulp. This air distribution and agitation moreover, effectively retard the settling of the metal particles or mineral values to the bottom of the cell and afford said values an increased opportunity to come into contact with the flotation reagents in the pulp.

It will be further noted that the converging baiile plates I3, I4 provide a crowding zone adjacent the rotor 36, bringing the pulp into par' ticularly intimate contact with the air, and enhancing the effect of the latter. Above said crowding zone, and in the region of the upper portions `of said plates and the lower portions of bailles I5, IB, is an expansion zone, wherein the bubbles produced by the air are afforded an opportunity to drop the gangue which is carried up therewith. Above said expansion zone, and between the converging bailes I5, I6is a coalescing zone of froth. At the top of'said bailies I5, I 6, the froth drains over said bailles and passes from the interior chamber 4I into the outer chambers 42, 43, between said ballles and the respective walls 4, 5.

It Willbe noted that the baille plates I3, I4 terminate at their lower ends above the bottom I of the cell. While the greater part of the air from the rotor 36 passes upwardly between said plates, a smaller portion (about ten percent, for example) passes beneath said plates and thence rises in the compartments 42 and 43. I'he froth produced in the inner compartment 4I, and thence owing over the batlles into the pulp in the outer compartments 42, 43, is subjected to a cleaning action by the air and reagents in the pulp in said outer compartments, whereby the mineralv values are afforded further opportunity to separate from such gangue as may be carried continuously rotated, and the air under pressure quired to produce the rougher concentrate, since a small amount of mineral values is distributed in a large quantity of pulp, and pronounced aeration and agitation are required to enable the reagents to come into contact with the mineral particles. After the mineral values are collected into a rougher concentrate, much less air and agitation are needed to separate the small amount of gangue from the large amount of mineral. In prior fiotation work, wherein the rougher concentrate is placed in a separate machine for cleaning, clear water is'generally added in the cleaning cell, owing to the greatly increased density of the concentrated material, but this addition of Water causes washing of the reagents away from some of the mineral values, causing them to settle to the bottom and be carried away with the tailing. In my apparatus, however, the rougher concentrate from the inner compartment drops into a pulp of proper density, which pulp also contains reagents, thus aording the mineral values an effective opportunity to separate from the gangue. Very high concentrates and remarkably clean tailings result.

It will thus be seen that my invention not only produces a particularly effective treatment of the pulp in the inner compartment 4I to producey a froth of high mineral value concentration, but also that it provides for the cleaning of said froth in the same cell to` further increase said concentration. The construction cost of my apparatus, moreover, is low, since there are no complicated parts.

'I'he power requirements are small, inasmuch as a low speed of operation of the rotor, as compared with all-mechanical notation machines, is suiiicient; and furthermore the rotor is buoyed up by th`e air therein. The air also prevents the coarse material from banking around the agitator and eliminates drag. In y addition, the entire mechanism may be constructed from light material, thus further reducing power consumption.

The apparatus above described is capable of handling heavy tonnages. An embodiment of such apparatus in actual operation has been treating some 200 tons of material in 24 hours,`

with a rotorF speed of about 150 revolutions per minute. Coarse material does not interfere with its operation. As the result of the thoroughness of the aeration and agitation, moreover, a desirable uniformity of pulp density is maintained throughout the pulp column. No sand bleeders are necessary. Nor are mechanical froth removers necessary, since the froth. is continually discharged into the froth launders by the effect of proper agitation.

The amount of froth produced is governed by the amount of air introduced through the porous in said froth. Thus, while a froth of high miny medium38. By varying the space between the baille plates I3, I4 and the bottom of the cell, the amount of air into the inner and outer compartments may be regulated to vary the roughing and cleaning effects as desired.

While none of the baiiles I3--I6 need be apertured, the provision of openings in some or all of the baffles, as indicated at I 1, enables some of the airin the inner compartment to passthrough said openings into the outer compartments, and thus to supplement the cleaning action of the air which passes into said outer compartments below the lower ends of the baille plates I 3 and I4.

iiowing over the Weir I0 are directed to the feed intake of the adjacent cell, instead of to waste,

and are passed into the inner compartment of said adjacent cell. The tailings from the outer compartment of the latter lmay then pass over the weir of said adjacent cell to waste, or toa third cell, and so on. Particularly heavy tonnages may be expeditiously handled in this manner. The cells of the series may be either on the same plane or on successively lower levels, in which case the flow of material through the series of cells is aided by gravity.

In Figure 9 I have shown an alternative means for introducing air into the rotor shaft 22. In this arrangementbearings 2 3', 2l' for said shaft are formed integrally, as by casting, with an intermediate hollow member 50, having an enlarged interior chamber 5I.` Air is led to said chamber 5| by pipe 52 which fits into an opening 53 in a wall of said member 50. The shaft 22 passes upwardly through the casting comprising said bearings 23', 24' and member 50. and is closed at its upper end in any suitable way, as by a plug 54. Near its upper end said shaft may have secured thereto a rope sheave 55 through which shaft-may be driven. The bearings 23', 24' may be bolted to the respective cross bars 25, 26 in the same way as are the previously described bearings 23. 24. The shaft 22 is provided with openings 56 for receiving the air introduced into chamber 5|. A thrust bearing may be provided for said shaft by a collar 51 which is secured to said shaft and rests upon a ball bearing assembly 58. Between said assembly 58 and the bearing 23 a packing gland 59 is interposed, said gland being held down by the weight of the shaft 22 and the rotor or impeller carried thereby. A packing gland 60 suitably held in place by plate 6i and bolts 62, is provided at the lower end of the bearing 24'. It will be seen that this arrangement enables air to be effectively introduced into the rotating shaft 22 without reauiringa stuffing box.

The terms and expressions which I have employed are used as terms of description and not 4of limitation, and I have no intention. in theuse of such terms and expressions, ofl excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim: l

l. Flotation apparatus comprising a cell adapted to contain a body of pulp, a rotor mounted for rotation in said cell about a substantially vertical axis, the `bottom of said rotor comprising porous material, and means for passing a gas into said rotor for emergence through said porous material, said rotor having blades projecting -K therefrom below said porous material for imparting an outward throw to gas' emerging through said material and for impelling pulp positively outwardly through the zone oigas injection.

2. Flotation apparatus comprising -a cell adapted to contain a body of pulp, a rotor mounted for rotation in said cell about a substantially vertical axis, the bottom of said rotor comprising porous material, and means for passing a gas into said rotor for emergence through said porous material, -said rotor having blades projecting -from the periphery thereof andI having other blades projecting therefrom below said porous material for imparting an outward throw to gas f emerging through said material and for impelling pulp positively outwardly through the zone of y gas injection.

3. Flotation apparatus comprising a cell adapted to contain a body of pulp, a rotor mounted in said cell for rotation about a substantially vertical axis, a porous medium arranged at the bottom of said rotor, means for passing a gas into said rotor for emergence through said porous medium, blades on said rotor below said porous medium for imparting an outward throw to gas emerging through said medium and for impelling pulp positively outwardly through the zone of gas injection, and baffles extending in said cell to points adjacent said blades and dividing said cell into compartments through which the pulp may circulate, said baffles diverging upwardly from points adjacent said blades to augment upward movement and circulation of the pulp.

4. Flotation apparatus comprising a cell having walls projecting upwardly from the bottom thereof and adapted to surround a body of pulp. baffles within the space defined by said walls and diverging downwardly from points below the top of said cell, baffles within the space defined by said walls and converging downwardly from the first-mentioned bailles, y the second-mentioned bailles terminating above the bottom of said cell, and means adjacent the lower ends of the secondmentioned baffles for supplying ,gas to the pulp in said cell, the convergence of said secondmentioned bailies providing a crowding zone in the lower portion of the space between said second-mentioned baffles for bringing the pulp into close association with the gas from said supplying means, and also providing a froth expansion zone above said crowding zone, the divergence of the first-mentioned baffles providing a continuation of said froth expansion zone `in the lower portion of the space between said of said cell, baffles within the space defined by, f said walls and converging downwardly from the first-mentioned baies, and means adjacent the lower ends of the second-mentioned baifles'for supplying gas to the pulp in said cell, the secondmentioned baffles terminating above the bottom of said cell, the convergence of said secondmentioned baiiies providingv a crowding zone in the lower portion of the space between said second-mentioned baffles for bringing the pulp into clase association with the gas from said supplying means and also providing a froth expansion zone above said crowding zone, and the divergence of the mst-mentionedbafiles providing a continuation of said froth expansion zone in the lower portion of the space between said first-mentioned baiiies and a froth coalescing zone above said expansion zone.

6. Flotation apparatus comprising a cell having walls projecting upwardly from the bottom thereof and adapted to surround a body of pulp, means in said cell for supplying gas to said pulp, baille means within the space. dened by said walls, said baille means dividing said cell into inner and outer compartments, said baiile means comprising bailles diverging 4downwardly from points below the top of said cell and baffles con- .verging downwardly from the first-mentioned baffles and terminating above the bottom of said cell, the convergence of the second-mentioned bailles providing a crowding zone in the lower portion of said inner compartment to bring the pulp into close association with the gas from said supplying means and a froth expansion zone a-bove said crowding zone, the divergence of the first-mentioned bailles providing a continuation of said froth expansion zone in the lower portion of the space between the first-mentioned bailles, said outer compartment having a froth receiving launder below the top of said first-mentioned baflles, the space between the top of said firstmentioned bailles and said launder providing for substantially unrestricted ow of froth from the top of said baille means to said launder.

7. Flotation apparatus comprising a cell adapted to contain a body of pulp, a rotor mounted in said cell for rotation about a substantially vertical axis, a porous medium arranged at the bottom of said rotor, means for passing a gas into said rotor for emergence through said porous medium, blades on said rotor below said porous medium for imparting an outward throw to gas emerging through said medium and for impelling pulp positively outwardly through the zone of gas injection, and baliles extending in said cell to points adjacent said blades and dividing said cell into compartments through which the pulp may circulate, said bailles diverging upwardly from points adjacent said blades to augment upward movement and circulation of the pulp, and other baffles converging upwardly from the rst mentioned baffles and providing a froth coalescing zone therebetween.

8. Flotation apparatus comprising a cell adapted to contain a body of pulp, a rotor mounted in said cell for rotation about a substantially vertical axis, a porous medium arranged at the bottom of said rotor, means for passing a gas into said rotor for emergence through said porous medium, blades on said rotor below said porous medium for imparting an outward throw to gas emerging through said medium and for lmpelling pulp positively outwardly through the zone of gas injection, and bailes extending in said cell to points adjacent said blades and dividing said cell into compartments through which the pulp may circulate, said bailles diverging upwardly from points adjacent said blades to augment upward mo'vement and circulation of the pulp, other baflies converging upwardly from the first mentioned baiiles and providing a froth coalescing zone therebetween, and a froth receiving launder means below the tops of said other bailles and spaced laterally therefrom, the space between the tops of said other bailles and said launder means providing for substantially unrestricted flow of froth from said baille tops to said launder means.

9. Flotation apparatus comprising a cell adapted to contain a body of pulp, baffles diverging downwardly from near the top of said cell, bales converging downwardly from the first mentioned baiiles, the second mentioned baflles terminating above the bottom of said cell, rotor means in the zone between said second mentioned baffles, said rotor means having a porous medium at the bottom therof, means for supplying gas to said rotor for emergence through said porous medium, and blades on said rotor below said porous medium for imparting an outward throw to gas emerging through said medium and -for impelling pulp outwardly through the zone of gas injection.

JOHN 'c. MACINTOSH.

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