WO2021084430A1

WO2021084430A1 - Rotor for self-aspirated flotation cells

Info

Publication number: WO2021084430A1
Application number: PCT/IB2020/060082
Authority: WO
Inventors: Thien SOK; Dariusz Lelinski; Bartosz Dabrowski; Lance CHRISTODOULOU; Ian COLTRIN; Muthu SRINIVASAN; Ronney Rodrigues SILVA
Original assignee: Flsmidth A/S
Priority date: 2019-10-28
Filing date: 2020-10-28
Publication date: 2021-05-06
Also published as: FI20225358A1; FI130400B

Abstract

A rotor (1) for a self-aspirated flotation cell (100) includes a body (2) having a base (25), and a bottom surface (19) that may be frustoconical. The rotor (1) may have a plurality of vanes (8) extending radially-outwardly from the body (2). A pumping cavity (9) may be centrally disposed within the rotor (1). The pumping cavity (9) may be defined below the bottom surface (19) and between inner surface portions (22) of the plurality of vanes (8). The plurality of vanes (8) may each extend from an upper vane surface (10) to a lower vane surface (18). The lower vane surfaces (18) may extend beyond the bottom surface (19) of the base (25).

Description

ROTOR FOR SELF-ASPIRATED FLOTATION CELLS

FIELD OF THE INVENTION

This invention relates to flotation cells, and more particularly to rotor apparatus for self- aspirated flotation machines which demonstrate improved power consumption, aeration, and/or pumping capabilities. The rotor apparatus is advantageously suited for forming bubbles in a mineral slurry and for encouraging particle -bubble attachment in selective froth flotation processes. The invention further relates to a method of retrofitting self-aspirated flotation machines with rotor apparatus described herein.

BACKGROUND OF THE INVENTION

Self-aspirated flotation machines, such as the FLSmidth® Wemco® self- aspirated flotation machine, typically have a rotor, a disperser surrounding the rotor, and a hood located above the disperser. A crowder above the disperser helps assist the movement of rising froth to one or more collection launders. A self-aspirated flotation machine is generally configured to suspend particles, ingest air, and provide means for bubble-particle contact within a flotation cell tank. Related publications include, for example, WO2015183806, W02019092620, US- 7,404,924, and US-6,095,336. These publications are hereby incorporated by reference herein in their entirety for any and all purposes as if fully set forth herein. It is desired to provide rotor apparatus for self-aspirated flotation cells which improves overall recovery performance of self- aspirated flotation machines.

OBJECTS OF THE INVENTION

It is, therefore, an object of some embodiments of the invention to increase recovery in self-aspirated flotation cells while maintaining the ability to keep slurry particles in suspension and naturally ingest air for purposes of bubble formation, without limitation.

It is further an object of some embodiments of the invention to provide a rotor which advantageously incorporates vanes having openings extending therethrough (e.g. elongated slots which may be arranged at an angle with respect to the direction of rotation of the rotor) for improved bubble sizing, enhanced bubble formation, better air entrainment, optimizing shear, promoting slurry- air contact, and/or reduction of power, without limitation.

It is yet another object of some embodiments of the invention to increase recovery by optimizing the flow and suspension of particles within the flotation cell, the amount of air naturally ingested by the cell, bubble size distributions, and/or the attachment between the particles and bubbles, without limitation.

Another objective of some embodiments of the invention is to improve the efficiency and performance of individual parts and components within a self-aspirated flotation cell - rather than rely on mere upsizing and/or scaling to meet customer demands, without limitation.

It is yet another object of some embodiments of the invention to provide a retrofittable solution which will enable an end user to easily replace an existing rotor (and/or draft tube section) within a self- aspirated flotation cell with a more efficient one to reduce operating costs

(OPEX), without limitation.

These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the aforementioned objects of the invention.

SUMMARY OF THE INVENTION

A rotor 1 for use within a self-aspirated flotation cell 100 may comprise a body 2. The body 2 may comprise a base 25 having a bottom surface 19. The rotor 1 may further comprise a plurality of vanes 8 extending radially-outwardly from the body 2. A pumping cavity 9 being centrally disposed within the rotor 1 may be provided to the rotor 1. For instance, the pumping cavity 9 may be defined below the bottom surface 19 as shown, between inner surface portions 22 of the plurality of vanes 8. The plurality of vanes 8 may each extend from an upper vane surface 10 to a lower vane surface 18. The lower vane surface 18 of each vane 8 preferably extends beyond the bottom surface 19 of the base 25 (i.e., lower vane surfaces 18) may be spaced from and located axially lower and more radially outward than the bottom surface 19 with respect to the installation orientation of the rotor 1 within the self-aspirated flotation cell 100, without limitation).

Vanes 8 of the rotor 1 may comprise at least one through opening 5 selected from the group consisting of: at least one aperture 6 and at least one elongated slot 7, without limitation. In some embodiments, each of the plurality of vanes 8 may comprise a convex outer surface portion 15, without limitation. In some embodiments, each of the plurality of vanes 8 may widen in their thickness as they extend radially outwardly from a narrower first width 11 which is more proximate to the body 2 to a wider second width 12 which is more proximate to an outer periphery of the rotor 1, without limitation. In some embodiments, each of the plurality of vanes 8 may comprise an upward protuberance 20 extending upwardly from their respective upper vane surface 10, without limitation. In some embodiments, the bottom surface 19 may comprise a downwardly projecting frustoconical surface, without limitation. Other bottom surface 19 shapes and configurations are anticipated.

In some embodiments, the body 2 may optionally comprise a hollowed opening 4 having a floor 23, without limitation. The hollowed opening 4 may be adequately configured to receive a driveshaft 103 of the self-aspirated flotation cell 100 therein, without limitation. In such a configuration, an anti-rotation/torque transmission feature such as a keyway, spline, setscrew, cotter pin, or shear bolt may be used to prevent spinning of driveshaft 103 within hollowed opening 4. The hollowed opening 4 may be alternatively employed to reduce material and/or reduce manufacturing costs, without limitations. The hollowed opening 4 may be internally threaded to receive a complimentary external thread provided to driveshaft 103. While not shown, it is envisaged that the shaft 3 of the rotor 1 may alternatively be externally-threaded and configured to be received in an internally-threaded recess provided within a distal end of the driveshaft 103.

In some embodiments, the width of the pumping cavity 9 may be greater at a lower portion of the pumping cavity 9 than it is at an upper portion of the pumping cavity 9, without limitation. In some embodiments, the at least one through opening 5 vanes 8 may comprise a plurality of elongated slots 7 arranged diagonally with respect to a turning axis of the rotor 1 , without limitation. In some embodiments, the plurality of elongated slots 7 may be parallel to each other, without limitation. In some embodiments, at least two of the plurality of elongated slots 7 may be different sizes or lengths, without limitation. In some embodiments, the at least one through opening 5 may comprise at least one aperture 6 and a plurality of elongated slots 7, without limitation.

In some embodiments, only some of the vanes 8 on the rotor 1 may comprise one or more of the through openings 5 discussed herein, whereas other vanes 8 may not comprise one or more through openings 5 without limitation. In some embodiments, a vane 8 may comprise a different number of through openings 5 than another vane 8, without limitation. In some embodiments, a vane 8 may comprise a different configuration of the one or more through openings 5 than another vane 8, without limitation. In some embodiments, one or more through openings 5 may be oriented or spaced differently on one vane 8 than another vane 8, without limitation.

In some embodiments, the convex outer surface portion 15 may extend between the upper vane surface 10 and the lower vane surface 18 along a radially-outward periphery of the rotor 1, without limitation. In some embodiments, the rotor 1 may comprise a straight surface portion 17 between the upper vane surface 10 and the lower vane surface 18, without limitation. In some embodiments, the rotor 1 may comprise a concave surface portion 16 between the convex outer surface portion 15 and the straight surface portion 17, without limitation.

In some embodiments, the vanes 8 may extend radially-outwardly the furthest at the convex surface portion 15, without limitation. In some embodiments, the vanes 8 may extend radially-outwardly the furthest at upper regions thereof. In other words, as shown in FIGS. 1 and 2, in some embodiments, vanes 8 may extend further radially outwardly near their upper vane surface 10 (or within their upper half) than they do proximate the lower vane surfaces 18 (or their lower half), without limitation. While not shown, it is envisaged that embodiments of a rotor 1 may comprise a vane 8 of the type shown in FIGS. 1 and 2, as well as a vane 8 of the type shown in FIGS. 3 and 4, without limitation.

According to some embodiments, a self-aspirated flotation cell 100 may comprise: a tank 106; at least one launder 115, 117; a drive 101 comprising a motor 102, a transmission 104, and a driveshaft 103; a draft tube 110 centrally located near a bottom 108 of the tank 106 and having a collar 113 mounted to a tubular body 112; and a rotor 1 as described above, which is mounted to the driveshaft 103 and located above and adjacent to the collar 113. A clearance 119 preferably optimized for pumping and/or shear preferably exists between the rotor 1 and the collar 113. In some embodiments, the collar 113 may be configured with an inner or outer surface that is formed to compliment and/or contour the shape of the rotor 1 , without limitation. For example, as suggested in FIGS. 10-11, the collar 112 may be formed to roll inwardly or flare out, respectively, without limitation.

According to some embodiments, a method of assembling the self-aspirated flotation cell 100 may involve the steps of: detaching an existing rotor from the driveshaft 103; detaching an existing collar from the tubular body 112 of the draft tube 110; removing the existing rotor from the tank 106; removing the existing collar from the tank 106; introducing a rotor 1 as described above to the tank 106; introducing a new collar 113 to the tank 106; mounting the rotor 1 to the driveshaft 103; and mounting the new collar 113 to the tubular body 112 of the draft tube 110. Preferably, an optimized clearance 119 is maintained between the rotor 1 and the new collar 113 after the steps of mounting the rotor 1 and mounting the new collar 113 are performed. According to some embodiments, a method of performing a flotation process may comprise the steps of: providing slurry to the self- aspirated flotation cell 100 described above; turning the driveshaft 103 and rotor 1 using the drive 101; and recovering froth rising to the top of the tank 106 using the at least one launder 115, 117.

It will be appreciated from this disclosure, and the drawings, that various features/components and method steps described herein may be altered without significantly departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

To complement the description which is being made, and for the purpose of aiding to better understand the features of the invention, a set of drawings illustrating preferred apparatus and methods of using the same is attached to the present specification as an integral part thereof, in which the following has been depicted with an illustrative and non-limiting character. It should be understood that like reference numbers used in the drawings may identify like components.

FIGS. 1 and 2 suggest a first non-limiting exemplary embodiment of a rotor which is within the scope of the present invention.

FIGS. 3 and 4 suggest a second non-limiting exemplary embodiment of a rotor which is within the scope of the present invention.

FIG. 5 suggest a side-cutaway view of a self-aspirated flotation machine configured with a rotor according to embodiments of the invention.

FIG. 6 is an isometric view of the self-aspirated flotation machine shown in FIG. 5. FIG. 7 is a partial close-up view of a portion of FIG. 6 more clearly showing a rotor provided in close proximity with a collar of a draft tube with a clearance therebetween.

FIG. 8 suggests a non-limiting exemplary embodiment of a method of retrofitting a rotor into an existing self-aspirated flotation machine.

FIGS. 9-11 suggest various non-limiting exemplary embodiments of a collar of a draft tube which may be optimized for close proximity use with a rotor described herein.

In the following, the invention will be described in more detail with reference to drawings in conjunction with exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention described herein and shown in the accompanying figures have shown, at least at a laboratory scale, to increase flotation recovery, reduce power draw, improve bubble formation, improve pumping capability, and/or enhance particle-bubble contact.

Turning to FIGS. 1-4, a rotor 1 comprises a body 2 from which a plurality of vanes 8 extend. A shaft 3 may extend upwardly from the body 2 as shown. As shown, the rotor may comprise 6 vanes, but may have as few as three or as great as sixteen vanes, without limitation. Defined at a base 25 of the body 2 and between radially-inside surfaces of the vanes 8 is a pumping cavity 9. The pumping cavity 9 may be defined between inner tapered or flared (i.e., angled) inner surface portions 22 of each vane 8 and below a bottom surface 19 of the body 2, and may take various forms and configurations depending on the shapes of tapered or flared inner surface portions 22 and bottom surface 19. As shown, the bottom surface 19 is configured in the form of a downwardly-projecting frustoconical surface; however, it is envisaged that alternative embodiments may incorporate a reverse upwardly-projecting frustoconical surface cavity or a flat surface, without limitation. A lower region of the pumping cavity 9 may further be defined by an optional inner transitional surface portion 21 of each vane which extends between a lower vane surface 18 and the tapered or flared inner surface portion 22.

As shown, the inner transitional surface portion 21 may be convex, and the tapered or flared inner surface portion 22 may be straight, without limitation. It should be understood that in some embodiments, the tapered or flared inner surface portion 22 may be arcuate, without limitation.

Each vane 8 may comprise one or more through openings 5 - preferably in the upper and radially-outward region of each vane 8. The one or more through openings 5 may comprise, for instance, one or more apertures 6, which may or not be symmetrical (e.g., circular as shown).

The one or more apertures 6 may take other geometrical shapes such as polygons (e.g., rectangles, triangles, hexagons, octagons, or the like), without limitation. The one or more through openings 5 may, alternatively, or, in addition to the one or more apertures 6 comprise, without limitation, one or more elongated slots 7. The one or more elongated slots 7 may, for example, be diagonally-arranged, and parallel-spaced as shown in the figures. However, it is envisaged that in some embodiments, the one or more elongated slots 7 may not be parallel to each other. It is further envisaged that in some embodiments, the one or more elongated slots 7 may extend vertically (purely up and down) or horizontally (extending in purely radial direction), rather than obliquely as shown, without limitation.

The body 3 may further optionally comprise a hollowed opening 4 to reduce material usage and/or to allow tubular materials, such as pipe, to form the body 2 and/or shaft 3 portions. The hollowed opening 4 may comprise a floor 23, so as to form a blind hole adjacent the base 25 of the body. In some embodiments, hollowed opening 4 may be configured to receive a driveshaft 103 of the self-aspirated flotation cell 100 therein, without limitation. The floor 23 may limit the depth of insertion of the driveshaft 103 into the body 3, without limitation. As previously mentioned above, one or more means for securing the driveshaft 103 within the hollowed opening 4 and/or enabling a transmission of torque from the drive shaft 103 to the rotor 1 may be provided, without limitation. For example, an anti-rotation/torque transmission feature such as a keyway, spline, setscrew, cotter pin, and/or shear bolt may be employed to the hollowed opening 4 in order to prevent spinning of driveshaft 103 within hollowed opening 4.

As previously mentioned, threaded engagement surfaces may be provided between the driveshaft 103 and rotor shaft (3), without limitation.

Each vane 8 comprises an upper vane surface 10. The upper vane surface may be straight as shown, but may alternatively be curved - for example, in an arcuate or compound curve shape, without limitation. A thickness of each vane 8 may change or grow as the vane extends radially-outwardly from the body 2. For example, as shown, each vane 8 may comprise a first (smaller) width 11 proximate to the body 2, and a second (larger) width 12 at a location of the vane 8 which is further radially-outward (e.g., at a point proximate the periphery of the rotor 1), without limitation.

Each vane 8 may be coupled to the body 2 by a fillet joint 13. The fillet joint 13 may comprise a web of additional material for strength. The fillet joint may, for example, include a weld bead from welding the vanes 8 to the body 2, or a thicker coating of polymer (rubber, or urethane) over an internal metal skeleton of the rotor 1. The rotor 1 may comprise a metallic (e.g., steel) core, and a polymeric (e.g., urethane or rubber) coating; or, the rotor 1 may be homogenously formed from a single uniform material, without limitation.

A profile of each vane 8 may comprise a convex outer surface portion 15 as shown. The convex outer surface portion 15 may extend between the upper vane surface 10 and the lower vane surface 18. As shown in the embodiment of FIGS. 3 and 4, the convex outer surface portion 15 may, in some embodiments, extend the entire distance between the upper vane surface 10 and the lower vane surface 18, without limitation. In some embodiments, such as the one depicted in FIGS. 1 and 2, the profile of each vane 8 may comprise a convex outer surface portion 15 which does not extend entirely between the upper vane surface 10 and the lower vane surface 18. For instance, the profile of each vane may additionally comprise a straight surface portion 17 extending to the lower vane surface 18, and/or a concave surface portion 16. In the embodiment shown in FIGS. 1 and 2, a concave surface portion 16 is shown to be situated between the convex outer surface portion 15 and a straight surface portion 17, without limitation.

In some embodiments, a portion of the upper vane surface 10 may comprise an upward protuberance 20 as shown in FIGS. 1 and 2. For example, as shown, a concave upper transition surface 14 may be provided between the radially-outward upward protuberance 20 and a radially- inward located flat portion of the upper vane surface 10, as shown, without limitation.

As shown, the upward protuberance 20 may be located at or near a radially outermost portion of each vane, proximate the upper vane surface 10. However, it is envisaged that an upward protuberance 20 may be located adjacent a more central region of upper vane surface 10, without limitation.

The shaft 3 of the rotor 1 may come in various lengths. As shown in FIGS. 5-7, the shaft 3 of the rotor 1 may comprise an integrally-formed or separable mounting flange 24 for connecting the rotor 1 to a driveshaft 103 of a self-aspirated flotation cell 100. In such a configuration, a number of fasteners 26 may be used to connect the rotor 1 to the driveshaft 103 of the self-aspirated flotation cell 100, at a connection 114. For example, after abutting the rotor mounting flange 25 to the mounting flange 118 of the driveshaft 103 and aligning the two with respect to each other, fasteners 26 may be used to secure the rotor 1 to the driveshaft 103 (see FIG. 7). Other connection means known in the art for coupling a rotor 1 to a driveshaft 103 may be employed and utilized, without limitation.

FIGS. 5-7 show one particular non-limiting exemplary embodiment of a self-aspirated flotation machine 100 comprising a rotor 1 and a modified collar 113 of a draft tube 110 in accordance with the invention. The self-aspirated flotation machine 100 comprises a drive 101 which turns a driveshaft 103. The drive 101 comprises a motor 102 which delivers torque to a transmission 104 (e.g., a belt and pulley system as shown). The drive 101 may comprise a shroud 120 that covers moving parts and shields drive 101 components from dust, elements of nature, and other potential contaminants. The self- aspirated flotation machine 100 may further comprise an air intake 105 for naturally ingesting air into its tank 106 for purposes of entraining air into the slurry contained therein, during operation.

The self-aspirated flotation machine 100 further comprises an inlet 107 for receiving incoming slurry and delivering the incoming slurry to the tank 106. An outlet (not shown or labeled for clarity) is provided to the tank 106 and serves to remove gangue material (e.g., tailings) from the cell and/or transfer un-floated material to a subsequent downstream flotation cell (which may be of the self-aspirated or forced-air type, without limitation). The self- aspirated flotation machine 100 comprises at its upper end, a main launder 117 for receiving froth and recovering floated hydrophobic particles from slurry entering inlet 107. The main launder 117 may be supplemented by a number of radial launders 115 and/or inner annular launders (not shown), without limitation.

A cone baffle 109 may be provided to the self-aspirated flotation cell 100 adjacent the bottom 108 of the tank 106, at a central inner portion of the tank 106 as shown. A draft tube 110 having a lower flared end 111 and upper tubular body 112 may be positioned above the cone baffle 109. The draft tube 110 may be comprised of multiple sections (e.g., modular or flanged, connectable sections), and may comprise an upper collar 113 as one of its multiple sections. For example, the collar 113 and another section of the tubular body 112 may each be provided with a flange at a flanged connection 116, without limitation. The flanged connection 116 may comprise fasteners 26, such as rivets or bolts extending through the respective flanges of the collar 113 and tubular body 112, without limitation.

The collar 113 of the draft tube 110 may be designed for optimal clearance 119 between the vanes 8 of the rotor 1 and the collar 113. This clearance 119 may be tailored for best pumping performance and/or to minimize wear to the collar 113 and/or rotor. The top lip of the collar 113 may be shaped and/or sized to: receive a lower portion of the rotor 1 (FIG. 9), compliment the shape of the rotor vanes 8 (FIGS. 9-11), and/or maximize pumping characteristics, reduce wear, reduce turbulence, or optimize flow of slurry transitioning from the inside of draft tube 110 to pumping cavity 9, without limitation. As shown in FIG. 10, an upper lip of the collar 113 may be rolled inwardly and/or may follow the profile of lower vane surfaces 18.

The self-aspirated flotation machine 100 may comprise a mounting flange 118 which is integrally- or separably-provided to the driveshaft 103. The rotor 1 may be connected to the driveshaft 103 at a connection 114. For example, as suggested in FIGS. 5-7, rotor 1 may comprise a mounting flange 24 which is configured to abut and mount to the mounting flange 118 of the driveshaft 103. The mounting flange 24 of the rotor 1 may be fastened to the mounting flange 118 of the driveshaft 103 by aligning and then securing the two mounting flanges 24, 118 together using fasteners 26, such as nuts and bolts, without limitation.

The rotor 1 may be surrounded by a specialized stator (e.g., as described in WO2015183806), or a disperser provided with a hood 121 as depicted in FIGS. 5 and 6, without limitation. A crowder 122 comprising a frustoconical annular surface may be employed to assist the movement of rising froth towards the main launder 117 (and/or to radial launders 115), without limitation.

A contractor or other entity may construct a rotor apparatus, provide a rotor apparatus, or operate a self- aspirated flotation cell 100 containing a rotor apparatus in whole, or in part, as shown and described. For instance, the contractor may bid or receive a bid award for a project related to designing or operating a rotor apparatus; or, the contractor may offer to design a rotor apparatus (or component thereof), or design a process for a client involving one or more of the features shown and described herein. The contractor may provide, for example, any one or more of the devices, features, or method steps shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices to an end user having a self-aspirated flotation cell 100. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer, and are within the spirit and scope of this disclosure. The contractor may subcontract the fabrication, delivery, sale, or installation of the devices or components disclosed, or of other devices which are used to provide said devices or components. The contractor may also survey a site and design or designate one or more storage areas for storing material used to manufacture the devices or components, or for storing the devices and/or components. The contractor may also maintain, modify, or upgrade the devices disclosed herein. The contractor may provide maintenance, modification, or upgrading services by subcontracting such services or by directly providing those services or components needed for said maintenance, modification, or upgrading. The contractor may modify a pre-existing self- aspirated flotation cell rotor apparatus or pre-existing draft tube collar apparatus, subassemblies thereof, components thereof, and/or parts thereof using one or more “retrofit kits” to arrive at a modified rotor or draft tube collar apparatus or method of operating or installing the same comprising one or more of the method steps, devices, components, or features discussed herein.

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

REFERENCE NUMERAL IDENTIFIERS Rotor Body Shaft Hollowed opening (optional) Through opening(s) Aperture(s) Elongated slot(s) (e.g., diagonally-arranged, parallel, different lengths) Vane(s) Pumping cavity Upper vane surface First width (e.g., smaller than second width) Second width (e.g., larger than first width) Fillet joint Concave upper transition surface Convex outer surface portion Concave surface portion Straight surface portion Fower vane surface Bottom surface (e.g., frustoconical) Upward protuberance Inner transitional surface portion Tapered or flared inner surface portion Floor (optional) Mounting flange (rotor) Base Fastener(s) Self-aspirated flotation cell Drive Motor

Driveshaft

Transmission (e.g., belt and pulley system)

Air intake

Tank

Inlet

Bottom

Cone baffle

Draft tube

Flared end

Tubular body

Collar

Connection

Radial launder

Flanged connection

Main launder

Mounting flange (shaft)

Clearance between vane and collar Shroud

Disperser with hood or stator Crowder

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A rotor (1) for use within a self-aspirated flotation cell (100) comprising: a body (2) having a base (25) and a bottom surface (19); a plurality of vanes (8) extending radially-outwardly from the body (2); a pumping cavity (9) centrally disposed within the rotor (1), the pumping cavity (9) being defined below the bottom surface (19) and between inner surface portions (22) of the plurality of vanes (8); the plurality of vanes (8) each extending from an upper vane surface (10) to a lower vane surface (18) which extend beyond the bottom surface (19) of the base (25).

2. The rotor (1) according to claim 1, further comprising at least one through opening (5) selected from the group consisting of: at least one aperture (6) and at least one elongated slot (7).

3. The rotor (1) according to any one of the preceding claims, wherein each of the plurality of vanes (8) comprises a convex outer surface portion (15).

4. The rotor (1) according to any one of the preceding claims, wherein each of the plurality of vanes (8) widens in thickness as they extend radially outwardly from a narrower first width (11) proximate to the body (2) to a wider second width (12) proximate an outer periphery of the rotor (1).

5. The rotor (1) according to any one of the preceding claims, wherein each of the plurality of vanes (8) comprises an upward protuberance (20) extending upwardly from an upper vane surface (10).

6. The rotor (1) according to any one of the preceding claims, wherein the bottom surface (19) comprises a downwardly projecting frustoconical surface.

7. The rotor (1) according to any one of the preceding claims, wherein the body (2) comprises a hollowed opening (4) with a floor (23).

8. The rotor (1) according to any one of the preceding claims, wherein a width of the pumping cavity (9) is greater at a lower portion of the pumping cavity (9) than it is at an upper portion of the pumping cavity (9).

9. The rotor (1) according to claim 2, wherein the at least one through opening (5) comprises a plurality of elongated slots (7) arranged diagonally with respect to a turning axis of the rotor (1).

10. The rotor (1) according to claim 9, wherein the plurality of elongated slots (7) are parallel to each other.

11. The rotor (1) according to claim 9 or 10, wherein at least two of the plurality of elongated slots (7) are different sizes or lengths.

12. The rotor (1) according to claim 2, wherein the at least one through opening (5) comprises at least one aperture (6) and a plurality of elongated slots (7).

13. The rotor (1) according to any one of the preceding claims, wherein the convex outer surface portion (15) extends between the upper vane surface (10) and the lower vane surface (18) along a radially-outward periphery of the rotor (1).

14. The rotor (1) according to any one of claims, further comprising a straight surface portion (17) between the upper vane surface (10) and the lower vane surface (18), and a concave surface portion (16) between the convex outer surface portion (15) and the straight surface portion (17).

15. The rotor (1) according to any one of claims, wherein the vanes (8) extend radially- outwardly the furthest at the convex surface portion (15).

16. The rotor (1) according to any one of claims, wherein the vanes (8) extend radially- outwardly the furthest at upper regions thereof than proximate the lower vane surfaces (18).

17. A rotor (1) for use within a self-aspirated flotation cell (100) comprising: a body (2) having a base (25) and a bottom surface (19); a plurality of vanes (8) extending radially-outwardly from the body (2); and, at least one through opening (5) selected from the group consisting of: at least one aperture (6) and at least one elongated slot (7) provided to at least one of the plurality of vanes

(8).

18. A self-aspirated flotation cell (100) comprising: a tank (106); at least one launder (115, 117); a drive (101) comprising a motor (102), a transmission (104), and a driveshaft (103); a draft tube (110); centrally located near a bottom (108) of the tank (106) and having a collar (113) mounted to an upper portion of a tubular body (112) at a connection (114); a rotor (1) as described in any one of claims 1-17, mounted to the driveshaft (103) and located above and adjacent to the collar (113); wherein a clearance (119) exists between the rotor (1) and the collar (113).

19. A method of assembling the self-aspirated flotation cell (100) described in claim 18, comprising: detaching an existing rotor from the driveshaft (103); detaching an existing collar from the tubular body (112) of the draft tube (110); removing the existing rotor from the tank (106); removing the existing collar from the tank (106); introducing a rotor (1) as described in any one of claims 1-16 to the tank (106); introducing a new collar (113) to the tank (106); mounting the rotor (1) as described in any one of claims 1-16 to the driveshaft (103); and mounting the new collar (113) to the tubular body (112) of the draft tube (110); wherein the clearance (119) between the rotor (1) and the new collar (113) is made after the steps of mounting the rotor (1) and mounting the new collar (113) are performed.

20. A method of performing a flotation process comprising: providing slurry to the self-aspirated flotation cell (100) described in claim 18; turning the driveshaft (103) and the rotor (1) using the drive (101); and recovering froth rising to the top of the tank (106) using the at least one launder (115,

117).