AU2002326989B2 - Flotation machine rotor and method of operation - Google Patents

Description

WO 03/026800 PCT/US02/29764 FLOTATION MACHINE ROTOR AND METHOD OF OPERATION Cross-Reference to Related Applications This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in Provisional Patent Application No.

60/324,031 filed on September 21, 2001.

Background of the Invention Flotation machines are commonly employed to separate solid material from a slurry typically composed of liquids and solids in varying proportions. An impeller located in the flotation machine agitates the slurry dispersing entrapped gas, thereby causing the formation of gas bubbles.

Particulate solid material adheres to the surface of the gas bubbles and rises therewith to the slurry surface forming a froth that has a higher concentration of adhered solid material, than does the slurry.

The froth, which is a combination of liquid, solid particles, and gas is removed from the flotation machine for further processing. The gas bubble/particle interaction is important to the flotation process as, without it, there can be no separation via the above-described method. To generate sufficient gas bubbles and thereby froth, gas is usually introduced through an opening in the impeller or rotor of the flotation machine. A prior art method of introducing the gas is shown in FIGS. 1, 2, and 3. Gas is introduced through apertures 12 in the rotor. These apertures tend to be large and located between successive pairs of rotor blades 14. The apertures 12 extend, in part through an upper surface 16 of the rotor 10, with the remainder of each aperture extending into a body portion 18 of the rotor.

During operation, particles tend to travel up the rotor body portion 18 following the contours thereof. The contours are generally smooth with no discontinuities or protuberances between successive rotor blades 14. As such, the peripheral edges of each aperture 12 follows the smooth contours of the rotor body portion 18.

A problem associated with rotors configured in the above-described manner is that there is a tendency for solid particles, to enter the rotor body portion 18, through the apertures 12. Another problem attributed to these prior art rotors is that the distribution of gas bubbles attributable to the air entering through an IO 2 Saperture is not optimal due to the apertures configuration. This in turn minimized the gas bubble/particle interaction and thereby the solid/liquid separation.

I Based on the foregoing it is the general object of the present invention to provide a flotation machine rotor that overcomes the problems and drawbacks of prior art rotors.

00 CSummary of the Invention r The present invention resides in one aspect to a flotation machine rotor comprising: a body portion defining an interior area adapted to communicate with a gas source; at least one rotor blade projecting radially outwardly from said body portion; at least one aperture defined by said body portion and in gaseous communication with said interior area, said aperture being positioned adjacent to said at least one rotor blade and being defined in-part by a lower peripheral edge; at least one lip projecting radially outwardly from said lower peripheral edge so that, during operation of said rotor, solid particles forming part of a solid/liquid slurry, travel away from said body portion and in approximate alignment with said aperture so that gas flowing from said aperture creates bubbles in said slurry that entrain at least a portion of said solid particles.

In practice, the gas bubbles generated by gas being expelled from the aperture entrain the solid particles thereby forming a froth of gas bubbles and entrapped particles on the slurry surface which is then skimmed off, clarifying the slurry.

Preferably, the aperture is in the form of a slot and extends in a longitudinal direction approximately perpendicular to a central axis defined by the rotor. In the preferred embodiment of the present invention there are a plurality of slots each having a lip projecting from a lower peripheral edge of each slot. In addition, the body portion can be contoured with a diameter defined thereby progressively increasing from a lower to an upper section of the body portion. The slots are positioned in the upper section of the body portion.

The present invention resides in another aspect in providing a H:\annteg\keep\apeci\2002326989.doc 24/05/06 3 zj rotor forming part of a flotation machine, said rotor including a body portion defining an interior area adapted to communicate with a gas source, a Ct plurality of rotor blades projecting radially outwardly form said body Sportion, at least one aperture defined by said body portion and in gaseous communication with said interior area, said aperture being positioned between successive rotor blades, said at least one aperture being defined inpart by a lower peripheral edge, and at least one lip projecting radially 00 outwardly from said lower peripheral edge; C introducing a liquid/solid slurry into said flotation machine; causing said rotor to spin about a central axis so that solid O particles forming part of said slurry move upwardly along said body portion Sand contact said lip projecting at least a portion of said solid particles radially away from said rotor and in approximate alignment with said aperture; causing gas to flow from said aperture, thereby forming bubbles defining a surface upon which a portion of said solid particles, that have passed over said lip, contact and are entrained thereon; forming a froth comprising said bubbles having said solid particles entrained thereon; and removing said froth from said flotation machine.

Brief Description of the Drawings FIG. 1 is a perspective view of a prior art flotation machine rotor.

FIG. 2 is a partial, top view of the rotor of FIG. 1.

FIG. 3 is a partial, cross-sectional view of the rotor of FIG. 1.

FIG. 4 is a perspective view of a flotation machine rotor embodying the present invention.

FIG. 5 is a top plan view of the rotor of FIG. 4.

FIG. 6 is a partial, cross-sectional view of the rotor of FIG. 4.

FIG. 7 is a partial, cross-sectional view of the rotor of FIG. 4.

FIG. 8 is an enlarged view of a portion of the rotor of FIG. 7.

FIG. 9 is a partial plan view and side elevational view of an alternate embodiment of the present invention.

Detailed Description of the Preferred Embodiment As shown in FIGS. 4 and 5, a flotation machine rotor embodying the present invention and generally designated by the reference number H\anneteg\keep\speci\2002326989.doc 24/05/06 3a Sincludes a plurality of rotor blades 42, each extending radially from a rotor body portion 44. The rotor body portion 44 defines a plurality of approximately horizontal slots 46 extending therethrough part-way between an upper and lower portion of the rotor 40. Each slot is defined in part by an upper and a lower peripheral edge, 43 and 45 respectively. The upper peripheral edge of each slot 46 being closer to an upper surface 47 of the Srotor 40. As used herein, the terms upper, lower, horizontal, vertical, and 00 C* the like are intended to apply only to the particular orientation of the rotor C as shown in the figures. Since other rotor orientations are possible, these S 10 terms should be broadly construed, and not interpreted in a limiting sense.

As shown in FIG. 6, the slots 46 each open into an interior area 48 defined by the rotor 40, and as will be explained in detail below are used to supply H.\annetteg\keep\speci\2002326989 doc 24/05/06 WO 03/026800 PCT/US02/29764 4 gas, usually air, into the rotor and thereby into the slurry introduced therein. The rotor defines an opening 49 in gaseous communication with the interior area 48.

The rotor body portion 44 includes a plurality of lips 50 each projecting radially outward from a lower peripheral edge 52 defined by each slot 46. The lips each cause a break in the otherwise smooth contour defined by the rotor body portion.

Turning to FIGS. 7 and 8, during operation the rotor 40 is positioned in a housing (not shown) and rotated at a predetermined speed by a suitable drive, such as, but not limited to a motor. A liquid/solid particle slurry is introduced into the housing and the rotation of the rotor 40 causes the solid particles entrained in the slurry to travel up the rotor body portion 44 over the lip 50 which acts to project the particles away for the rotor where gas flowing through each slot 46 causes the formation of air bubbles 52 that contact and entrain the solid particles.

The rotor 40, in order to introduce gas bubbles into the slurry is coupled to a gas source that is in gaseous communication with the aperture 49 and thereby the interior area 48, see Fig. 5. The gas bubbles having the particles entrained thereon are shown in the illustrated embodiment as element 54. These gas bubbles having solid particles entrained thereon are carried to a point where they can be removed from the flotation machine. An advantage of the present invention is that the lips will aid in the prevention of particles entering the interior of the rotor as well as in placing the particles in the gas stream flowing from the slots 46. In addition, the slots provide large gas bubble/particle contact areas. Furthermore, the combination of the slots and lips can cause a venturi-like effect pulling greater quantities of gas through the slots. While approximately horizontal slots have been shown and described, the present invention is not limited in this regard as other orientations such as, but not limited to vertical slots can be substituted without departing from the broader aspects of the present invention.

While a single circumferentially disposed row of slots 46 has been shown and described, the present invention is not limited in this regard. As shown in FIG. 9, more than one circumferentially disposed row of slots 46 (two shown) each having a radially protruding lip 50 associated therewith, can be provided without departing from the broader aspects of the present invention. While preferred embodiments have been shown and described, various modifications and substitutions may be made without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of example, and not by limitation.

4a SIn the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Further, reference herein to prior art is not intended to imply 00 0" that such prior art forms or formed a part of the common general CN- knowledge.

010 Hi\annetteg\keep\speci\2002326989.doc 24/05/06

Claims (11)

1. A flotation machine rotor comprising: a body portion defining an interior area adapted to communicate with a gas source; at least one rotor blade projecting radially outwardly from said body portion; at least one aperture defined by said body portion and in gaseous communication with said interior area, said aperture being positioned adjacent to said at least one rotor blade and being defined in-part by a lower peripheral edge; at least one lip projecting radially outwardly from said lower peripheral edge so that, during operation of said rotor, solid particles forming part of a solid/liquid slurry, travel away from said body portion and in approximate alignment with said aperture so that gas flowing from said aperture creates bubbles in said slurry that entrain at least a portion of said solid particles.

2. A flotation machine rotor as defined by claim 1, wherein said aperture is a slot that extends in a longitudinal direction approximately perpendicular to a central axis defined by said rotor.

3. A flotation machine rotor as defined by claim 2, wherein: said at least one rotor blade includes a plurality of rotor blades; said slot includes a plurality of slots, each positioned between a pair of said rotor blades each of said slots being defined in- part by an upper peripheral edge and a lower peripheral edge; and wherein said at least one lip includes a plurality of lips, each adjacent to and projecting outwardly from said lower peripheral edge of one of said slots.

4. A flotation machine rotor as defined by claim 1, wherein: said body portion defines an opening in gaseous communication with said interior area. A flotation machine rotor as defined by claim 4, wherein said opening is in communication with a gas source.

WO 03/026800 PCT/US02/29764 6

6. A flotation machine rotor as defined by claim 1, wherein said body portion is contoured.

7. A flotation machine rotor as defined by claim 6, wherein said body portion is approximately symmetrical about a central axis and progressively increases in diameter from a lower to an upper portion.

8. A flotation machine rotor as defined by claim 1, wherein said aperture is positioned in an upper portion of said body.

9. A method for operating a flotation machine rotor, comprising: providing a rotor forming part of a flotation machine, said rotor including a body portion defining an interior area adapted to communicate with a gas source, a plurality of rotor blades projecting radially outwardly from said body portion, at least one aperture defined by said body portion and in gaseous communication with said interior area, said aperture being positioned between successive rotor blades, said at least one aperture being defined in-part by a lower peripheral edge, and at least one lip projecting radially outwardly from said lower peripheral edge; introducing a liquid/solid slurry into said flotation machine; causing said rotor to spin about a central axis so that solid particles forming part of said slurry move upwardly along said body portion and contact said lip projecting at least a portion of said solid particles radially away from said rotor and in approximate alignment with said aperture; causing gas to flow from said aperture, thereby forming bubbles defining a surface upon which a portion of said solid particles, that have passed over said lip, contact and are entrained thereon; forming a froth comprising said bubbles having said solid particles entrained thereon; and removing said froth from said flotation machine. -7-

10. A flotation machine rotor substantially as herein described with reference to accompanying Figures 4 to 9. C 5

11. A method for operating a flotation machine rotor substantially as herein described with reference to accompanying Figures 4 to 9. 00 oO N Dated this 25th day of May 2006 S 10 GL&V MANAGEMENT HUNGARY KFT SBy their Patent Attorneys SGRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H\annette\keep\peci\2002326989.doc 24/05/06