FLOTATION CELL

Abstract

A flotation cell for treating particles suspended in slurry. The flotation cell includes a fluidized bed, a recovery zone at the upper part of the flotation cell, a launder lip and a recovery launder, and a tailings outlet. A primary slurry feed including fresh slurry is arranged to be fed into the flotation cell by a first feed inlet at a first position; and a secondary slurry feed including at least slurry recirculated from a flotation cell is arranged to be fed into the fluidized bed by a second feed inlet at a second position, below the first position. The slurry recirculated from the flotation cell is obtained at a third position between the recovery launder and the tailings outlet. A use of the flotation cell as well as a method for treating particles suspended in slurry are also disclosed.

Claims

1. A flotation cell for treating particles suspended in slurry and for separating the slurry into underflow and overflow, the flotation cell comprising a fluidized bed formed by fluid feed configured to supply a fluid to the flotation cell, and by a flotation gas feed configured to supply flotation gas, in which fluidized bed flotation gas bubbles adsorb to hydrophobic particles to form bubble-particle agglomerates that rise towards the top of the flotation cell; a recovery zone at an upper part of the flotation cell, configured to collect the bubble-particle agglomerates rising in the fluidized bed; a launder lip and a recovery launder arranged at the top of the flotation cell, and arranged to remove particles collected in the recovery zone from the flotation cell as overflow; and a tailings outlet arranged below the recovery launder and arranged to remove non-collected particles descending from the recovery zone as underflow; wherein the flotation cell has a height measured from the bottom of the flotation cell to the launder lip, wherein a primary slurry feed comprising fresh slurry is arranged to be fed into the flotation cell by a first feed inlet at a first position within an upper 50% of the flotation cell height and higher than the tailings outlet; and in that a secondary slurry feed comprising at least slurry recirculated from a flotation cell is arranged to be fed into the fluidized bed by a second feed inlet at a second position below the first position, so as to contribute to the formation of the fluidized bed, the slurry recirculated from the flotation cell obtained at a third position between the recovery launder and the tailings outlet.

2. The flotation cell according to claim 1, wherein the recovery zone is arranged above the fluidized bed.

3. The flotation cell according to claim 1, wherein the recovery zone is arranged at an upper part of the fluidized bed.

4. The flotation cell according to claim 1, wherein the primary slurry feed is arranged to be fed into the flotation cell at a position within an upper 30% of the flotation cell height.

5. The flotation cell according to claim 1, wherein the primary slurry feed is arranged to be fed into the recovery zone.

6. The flotation cell according to claim 1, wherein the first feed inlet is arranged at the centre of the flotation cell.

7. The flotation cell according to claim 6, wherein the first feed inlet comprises a circular section arranged to distribute the primary slurry feed evenly around the centre of the flotation cell.

8. The flotation cell according to claim 1, wherein the primary slurry feed is arranged to be fed into the fluidized bed so that the primary slurry feed has a flow direction counter-current to the rising bubble-particle agglomerates.

9. The flotation cell according to claim 8, wherein the first feed inlet comprises a sparger.

10. The flotation cell according to claim 1, wherein the primary slurry feed is arranged to be fed into the fluidized bed from a perimeter of the flotation cell so that the primary slurry feed has a flow direction substantially perpendicular to the rising bubble-particle agglomerates.

11. The flotation cell according to claim 10, wherein the first feed inlet comprises a sparger assembly arranged into a sidewall of the flotation cell, the sparger assembly arranged to create flotation gas bubbles, to cause attachment of flotation gas bubbles onto particles in the primary slurry feed, and to introduce the primary slurry feed into the fluidized bed.

12. The flotation cell according to claim 11, wherein the sparger assembly is arranged radially around a perimeter of the flotation cell.

13. The flotation cell according to claim 11, wherein the sparger assembly comprises jetting spargers, or cavitation spargers, or Venturi spargers.

14. The flotation cell according to claim 1, wherein the fluid feed comprises flotation gas feed.

15. The flotation cell according to claim 1, wherein the second feed inlet comprises flotation gas feed.

16. The flotation cell according to claim 1, wherein the secondary slurry feed is arranged to be fed into the fluidized bed so that the secondary slurry feed has a flow direction counter-current to the rising bubble-particle agglomerates.

17. The flotation cell according to claim 16, wherein the second feed inlet comprises a sparger.

18. The flotation cell according to claim 1, wherein the secondary slurry feed is arranged to be fed into the fluidized bed from the perimeter of the flotation cell so that the secondary slurry feed has a flow direction substantially perpendicular to the rising bubble-particle agglomerates.

19. The flotation cell according to claim 18, wherein the second feed inlet comprises a number of feed openings arranged into the sidewall of the flotation cell.

20. The flotation cell according to claim 1, wherein the secondary slurry feed is arranged to be fed into the fluidized bed so that it has a flow direction concurrent to the rising bubble-particle agglomerates.

21. The flotation cell according to claim 1, wherein the second feed inlet comprises the fluid feed.

22. The flotation cell according to claim 1, wherein secondary slurry feed comprises slurry recirculated from the flotation cell via a recirculation circuit, and obtained at the third position which is arranged lower than the launder lip and higher than the first position at which the primary slurry feed is arranged to be fed into the flotation cell.

23. The flotation cell according to claim 1, wherein the secondary slurry feed comprises slurry recirculated from the flotation cell via a recirculation circuit, and obtained at the third position which is arranged lower than the first position.

24. The flotation cell according to claim 1, wherein the recovery zone comprises a froth layer at the top of the flotation cell.

25. The flotation cell according to claim 23, wherein the primary slurry feed is arranged to be fed into the froth layer.

26. The flotation cell according to claim 1, wherein the recovery zone comprises no froth layer and that the flotation cell is arranged to be operated with constant slurry overflow.

27. The flotation cell according to claim 22, wherein the recirculation circuit comprises a pump arranged to intake a slurry fraction from the third position and to forward the slurry fraction into the second feed inlet as secondary slurry feed.

28. The flotation cell according to claim 22, wherein the recirculation circuit comprises a third feed inlet for introducing a feed of slurry into the secondary slurry feed prior to the secondary slurry feed being fed into the flotation cell via the second feed inlet.

29. The flotation cell according to claim 1, wherein the secondary slurry feed comprises slurry recirculated from a further flotation cell separate to the flotation cell.

30. The flotation cell according to claim 1, wherein the tailings outlet is arranged below the second feed inlet.

31. The flotation cell according to claim 1, wherein the secondary slurry feed comprises fine particles having a P80 50% or less of the P80 of the primary slurry feed.

32. The flotation cell according to claim 1, wherein the primary slurry feed comprises at least 20 w-% particles having a size of at least 300 μm.

33. The flotation cell according to claim 1, wherein it has a diameter of at least 1.0 m, preferably over 2 m, and most preferably between 2 and 8 m, at the height of the second position.

34. Use of the flotation cell according to claim 1 in recovering a valuable material suspended in slurry.

35. The use according to claim 34, in recovering particles comprising Cu from low grade ore.

36. A method for treating particles suspended in slurry and for separating the slurry into underflow and overflow in a flotation cell according to claim 1, wherein feeding a primary slurry feed comprising fresh slurry into the flotation cell via a first feed inlet; feeding a secondary slurry feed comprising at least slurry recirculated from a flotation cell into a fluidized bed via a second feed inlet so as to contribute to the formation of the fluidized bed; and by obtaining the slurry recirculated from the flotation cell at a third position between a recovery launder and a tailings outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The accompanying drawings, which are included to provide a further understanding of the current disclosure and which constitute a part of this specification, illustrate embodiments of the disclosure and together with the description help to explain the principles of the current disclosure. In the drawings:

[0090] FIGS. 1-5a, 5b present vertical cross-sectional views of embodiments of the flotation cell according to the invention; and

[0091] FIG. 6 shows two flotation cells of which at least one, flotation cell 1, is a flotation cell according to the invention.

DETAILED DESCRIPTION

[0092] Reference will now be made in detail to the embodiments of the present disclosure, an example of which is illustrated in the accompanying drawing.

[0093] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utilize the flotation cell, its use and the method based on the disclosure. Not all steps of the embodiments are discussed in detail, as many of the steps will be obvious for the person skilled in the art based on this disclosure.

[0094] For reasons of simplicity, item numbers will be maintained in the following exemplary embodiments in the case of repeating components. Directions of flow are indicated with arrows.

[0095] The enclosed FIGS. 1-6 illustrate a flotation cell 1 in some detail. The figures are not drawn to proportion, and many of the components of the flotation cell 1 are omitted for clarity.

[0096] The flotation cell 1 according to the invention is intended for treating mineral ore particles suspended in slurry and for separating the slurry into an underflow 400 and an overflow 500, the overflow 500 comprising a concentrate of a desired (valuable) mineral.

[0097] The flotation cell 1 comprises a fluidized bed 10 with a fluid feed 11 for supplying a fluid into the flotation cell to form and maintain a fluidized bed 10. In the fluidized bed 10, flotation gas bubbles adsorb to hydrophobic particles comprising valuable material to form bubble-particle agglomerates. The bubble-particle agglomerates rise toward an upper part 13 of the flotation cell 1 in the fluidized bed 10. The flotation cell 1 has a height H, measured from a bottom 110 of the flotation cell 1 to a launder lip 26.

[0098] The flotation cell 1 comprises a flotation gas feed for supplying flotation gas. The flotation gas feed may, for example, be incorporated into the fluid feed 11. Alternatively or additionally, the flotation gas feed may be incorporated into a first feed inlet 14 which supplies a primary slurry feed 100 into the flotation cell 1. Alternatively or additionally, the flotation gas feed may be incorporated into a second feed inlet 15 which supplies a secondary slurry feed 200 into the fluidized bed 10. Alternatively or additionally, the flotation cell 1 may comprise a flotation gas feed in the form of an agitator 18, for example a mechanical mixer comprising a rotor-stator assembly, disposed adjacent, i.e. at or near, the bottom 110 of the flotation cell 1, below the fluidized bed 10. The agitator may also be arranged so that it is situated within the fluidized bed 10. Such embodiments are shown in FIGS. 2 and 4.

[0099] The flotation cell 1 further comprises a recovery zone 20 arranged at the upper part 13 of the flotation cell, and configured to collect the bubble-particle agglomerates rising in the fluidized bed 10. The recovery zone 20 may be arranged above the fluidized bed. Alternatively, the recovery zone 20 may be arranged at an upper part 19 of the fluidized bed 10.

[0100] The bubble-particle agglomerates ascending in the fluidized bed 10 become transported to the recovery zone 20. The recovery zone 20 may comprise a froth layer 25 at the top of the flotation cell 1. The recovery zone 20 floats the bubble-particle agglomerates rising from the fluidized bed 10 to the froth layer 25. Alternatively, the recovery zone 20 may comprise no discernible froth layer, in which case the flotation cell is arranged to be operated with constant, and intentional, slurry overflow, i.e. as an overflow flotation cell.

[0101] A recovery launder 24 and the launder lip 26 are disposed at the top of the flotation cell 1, and arranged to remove particles collected in the recovery zone 20 as overflow 500 comprising a concentrate of desired (valuable) material. The recovery launder 24 may be a perimeter launder, with a launder lip 26 surrounding the perimeter 16 of the flotation cell 1, at the top of the flotation cell 1, over which launder lip 26 the collected particles flow into the recovery launder 24, as is known in the art.

[0102] A tailings outlet 12 is arranged below the recovery launder 24, and arranged to remove non-collected particles descending from the recovery zone 20 as underflow 400. The tailings outlet 12 may arranged in the form of a perimeter tailings launder continuously surrounding the entire perimeter 16 of the flotation cell (FIGS. 1, 2). Alternatively, the tailings outlet 12 may be sectional, i.e. not continuous around the perimeter 16. In yet an alternative embodiment, the tailings outlet 12 may comprise a simple outlet or opening at the perimeter of the flotation cell 1 (FIGS. 3, 4 and 5a, 5b). The tailings outlet 12 may be located below the second feed inlet 15.

[0103] The primary slurry feed 100 comprises fresh slurry, which may originate from a grinding step or grinding arrangement, from underflow or tailings of another flotation cell or another part of a flotation arrangement or flotation line of which the flotation cell 1 is a part. In an embodiment, the primary slurry feed 100 comprises fresh slurry that has not been classified or fractioned after grinding. In an embodiment, the primary slurry feed 100 comprises coarse particles, for example ore particles having a P80 of 500-600 μm. In an embodiment, at least 20 w-% of the particles in the primary slurry feed 100 have a size of at least 300 μm.

[0104] The primary slurry feed 100 is fed into the flotation cell 1 by the first feed inlet 14. The primary slurry feed 100 is arranged to be fed into the flotation cell 1 at a first position P, which is located within an upper 50% ½H of the flotation cell height H, and higher than the tailings outlet 12. In an embodiment, the primary slurry feed 100 is arranged to be fed into the flotation cell 1 at a position P within an upper 30% of the flotation cell height H. In an embodiment, the primary slurry feed 100 is arranged to be fed into the recovery zone 20.

[0105] In an embodiment, the first feed inlet 14 is arranged at the centre C of the flotation cell 1, which is also the centre of the fluidized bed 10 and the recovery zone 20. In an embodiment, the first feed inlet 14 comprises a circular section 140 through which the primary slurry feed 100 is fed into the flotation cell 1. The circular section 140 encompasses the centre C of the flotation cell 1 and is arranged to distribute the primary slurry feed 100 evenly around the centre C of the flotation cell 1. The circular section 140 may for example comprise a circular trough or pipe/tube, which may have an open upper side, or comprise openings, so that the primary slurry feed 100 led into the circular section 140 may flow through the open upper side or the openings in a controlled manner.

[0106] In an embodiment, the primary slurry feed 100 is arranged to be fed into the flotation cell 1/fluidized bed 10 so that it has a flow direction counter-current to the rising bubble-particle agglomerates, as well as the direction of flow of the fluid fed into the fluidized bed 10 by the fluid feed 11 (see FIGS. 1, 2, 6). The first feed inlet 14 may comprise a sparger or a number of spargers. Any other suitable feed inlet such as a downcomer or a pipe or conduit may be used as the first feed inlet 14.

[0107] Alternatively, the primary slurry feed 100 may be arranged to be fed into the flotation cell 1/fluidized bed 10 from the perimeter 16 of the flotation cell 1 so that the primary slurry feed 100 has a flow direction substantially perpendicular to the rising bubble-particle agglomerates. Accordingly, the first feed inlet 14 may comprise a sparger assembly 141 arranged into a sidewall 17 of the flotation cell 1, the sparger assembly 141 arranged to create flotation gas bubbles, to cause attachment of flotation gas bubbles onto particles in the primary slurry feed 100, and to introduce the primary slurry feed 100 into the flotation cell 1/fluidized bed 10. The sparger assembly 141 may comprise a number of spargers arranged radially around the perimeter 16 of the flotation cell 1, so that each sparger is evenly spaced from each other.

[0108] The spargers may be cavitation spargers, jetting spargers or Venturi spargers, and thus the sparger assembly 141 and the first feed inlet 14 may comprise flotation gas feed.

[0109] The sparger assembly 141, i.e. the spargers, may also serve in generating flotation gas bubbles with an appropriate size distribution by injecting flotation gas into the primary slurry feed 100. For example, a jetting sparger (such as SonicSparger™ Jet), based on ultrasonic injection of air or air and water, may be utilized. Another example of a sparger is a cavitation or Venturi sparger (such as SonicSparger™ Vent), the operation of which is based on the Venturi principle which is highly efficient in generating large amount bubbles with relatively small size (0.3-0.9 mm). In a cavitation sparger, a recirculate of slurry from the flotation cell is forced through the sparger to generate bubbles through cavitation.

[0110] Also any other suitable type of feed inlets known in the art may be used as the first feed inlet 14.

[0111] The secondary slurry feed 200 comprises at least slurry recirculated from a flotation cell 1, 2. The secondary slurry feed 200 is arranged to be fed into the fluidized bed 10 by the second feed inlet 15, located at a second position S, which is arranged below the first position P. The secondary slurry feed 200 contributes to the formation of the fluidized bed 10.

[0112] The slurry recirculated from the flotation cell 1, i.e. the same flotation cell 1, is obtained at a third position R, which is located between the recovery launder 24 and the tailings outlet 12. In an embodiment, the third position R is arranged lower than the launder lip 26 and higher than the first position P at which the primary slurry feed 100 is arranged to be fed into the flotation cell 1. Alternatively, the slurry recirculated from the flotation cell 1 may be obtained at the third position R arranged lower than the first position P.

[0113] In an embodiment, alternatively or additionally, the secondary slurry feed 200 comprises slurry 300 recirculated from a further flotation cell 2, separate to the flotation cell 1 (FIG. 6). This recirculated slurry 300 may, for example, comprise a slurry fraction taken similarly from a position R of the further flotation cell 2, or it can comprise overflow or underflow from a further flotation cell, or a combination of overflow or underflows from several further flotation cells, and having a similar particle size distribution as the slurry in the fluidized bed 10 of the flotation cell 1.

[0114] In yet another embodiment, alternatively or additionally, the secondary slurry feed 200 may comprise a feed of slurry 300 from another part of the flotation line or flotation arrangement, for example from classification, fractionation or grinding. The feed of slurry 300 may, for example, be fresh slurry similar to the fresh slurry comprised by the primary slurry feed 100.

[0115] In general, recirculating slurry in the manner as described in connection with the secondary feed 200, it may be possible to control the mass balance of the flotation cell 1 in an efficient manner.

[0116] In an embodiment, the secondary slurry feed 200 comprises fine particles having a P80 50% or less of the P80 of the primary slurry feed 100. For example, the secondary slurry feed 200 may comprise fine particles having a P80 of approximately 200 μm.

[0117] The secondary slurry feed 200 is fed into the flotation cell 1, into the fluidized bed 10 by the second feed inlet 15. The secondary slurry feed 200 contributes to the formation of the fluidized bed 10, and may thus decrease the need of fresh water in the fluid via the fluid feed 11. The secondary slurry feed 200 may have a flow direction divergent from the rising bubble-particle agglomerates in the flotation cell 1. Alternatively, the secondary slurry feed 200 may have a flow direction concurrent with the rising bubble-particle agglomerates.

[0118] In an embodiment, the secondary slurry feed 200 is arranged to be fed into the flotation cell 1/fluidized bed 10 so that the secondary slurry feed 200 has a flow direction counter-current to the rising bubble-particle agglomerates (see FIGS. 4, 5a), as well as the direction of flow of the fluid fed into the flotation cell 1 by the fluid feed 11. The second feed inlet 15 may comprise a sparger or a number of spargers. Any other suitable feed inlet such as a downcomer or a pipe or conduit may be used as the second feed inlet 15.

[0119] In an alternative embodiment, the secondary slurry feed 200 is arranged to be fed into the flotation cell 1/fluidized bed 10 from the perimeter 16 of the flotation cell 1 so that the flow direction of the secondary slurry feed 200 is substantially perpendicular to the rising bubble-particle agglomerates (see FIGS. 1, 2). In this case, the second feed inlet 15 may comprise a number of feed openings 150 arranged into a sidewall 17 of the flotation cell 1. The feed openings 150 may be arranged into the sidewall 17 evenly distributed along the perimeter 16 of the flotation cell 1 so as to form a circle or gird of evenly-spaced apart feed openings 150. Also in this case, the feed openings may comprise spargers, similarly to the solutions presented in connection with the first feed inlet 14.

[0120] In a yet another alternative embodiment, the secondary slurry feed 200 is arranged to be fed into the flotation cell 1/fluidized bed 10 so that the secondary slurry feed 200 has a flow direction concurrent to the rising bubble-particle agglomerates (see FIGS. 3, 5b). For example the second feed inlet 15 may be incorporated with the fluid feed 11, i.e. the second feed inlet 15 comprises the fluid feed 11, as is shown in FIG. 3, and the secondary slurry feed 200 fed into the flotation cell 1/fluidized bed 10 from the bottom 110 of the flotation cell 1. It is also possible that the second feed inlet 15 comprises the fluid feed 11 also in the embodiments where the flow direction of the secondary slurry feed 200 is divergent from the rising bubble-particle agglomerates, i.e. also when the second feed inlet 15 is arranged as shown in FIG. 1, 2, 4 or 5a. In some cases, it may be possible to significantly reduce the amount of fluid needed to maintain the fluidized bed 10 due to the employment of secondary slurry feed 200 in this purpose, in the manner described above.

[0121] In all of the above embodiments, the second feed inlet 15 and/or the feed openings 150 may comprise for example spargers, such as cavitation spargers, jetting spargers or Venturi spargers, and thus the feed openings 150 (and the second feed inlet 15) may comprise flotation gas feed.

[0122] The feed openings 150, such as spargers, may also serve in generating flotation gas bubbles with an appropriate size distribution by injecting flotation gas into the secondary slurry feed 200. For example, a jetting sparger (such as SonicSparger™ Jet), based on ultrasonic injection of air or air and water, may be utilized. Another example of a sparger is a cavitation or Venturi sparger (such as SonicSparger™ Vent), the operation of which is based on the Venturi principle which is highly efficient in generating large amount bubbles with relatively small size (0.3-0.9 mm). In a cavitation sparger, a recirculate of slurry from the flotation cell is forced through the sparger to generate bubbles through cavitation.

[0123] Also any other suitable type of feed inlets known in the art may be used as the second feed inlet 15 and/or feed openings 150.

[0124] The secondary slurry feed 200 comprising slurry recirculated from the flotation cell 1 may be recirculated via a recirculation circuit 3. The recirculation circuit 3 may comprise a pump 30 arranged to intake a slurry fraction from the third position R, and to forward the slurry fraction into the second feed inlet 15 as secondary slurry feed 200, or as a part of the secondary slurry feed 200.

[0125] In an embodiment, the recirculation circuit 3 comprises a third feed inlet 31 for introducing a feed of slurry 300 into the secondary slurry feed 200 prior to the secondary slurry feed 200 being fed into the flotation cell 1 via the second feed inlet 15. As described above, the feed of slurry 300 may comprise any suitable additional fraction of slurry taken from another part of a flotation line or arrangement of which the flotation cell 1 is a part.

[0126] In an embodiment, the primary slurry feed 100 is arranged to be fed into the froth layer 25 of the flotation cell 1, i.e. the first position P at which the primary slurry feed 100 is introduced into the flotation cell 1 is arranged at the upper part 13 of the flotation cell, right at the height of the froth layer 25 (see FIGS. 5a and 5b). The first feed inlet 15 may, for example be arranged at one point at the perimeter 16 of the flotation cell 1. The recovery launder 24, in this case, may be an outlet arranged at another point at the perimeter 16, for example substantially opposite the first feed inlet 15. The secondary slurry 200 comprises slurry recirculated from the flotation cell 1 via a recirculation circuit 3, and obtained at the third position R which is arranged lower than the first position P. The secondary slurry feed 200 may have a flow direction divergent (counter-current, perpendicular) from the rising bubble-particle agglomerates (FIG. 5a), or a flow direction concurrent with the rising bubble-particle agglomerates (FIG. 5b).

[0127] The flotation cell 1 may have circular cross-section. The flotation cell 1 may have a diameter of at least 1.0 m, measured at the height of the second position S. The flotation cell 1 may have a diameter of over 2 m. The flotation cell may have a diameter between 2 to 8 m, for example 2.25 m; 3.5 m; 5 m; 6.75 m; or 7.8 m. The flotation 1 may also have a cross-section that is divergent from circular, e.g. rectangular or square. In case the cross-section is not circular, the diameter is measured as the maximum diagonal of the cross-sectional form.

[0128] The flotation cell 1 may have a substantially level bottom. The manner of feeding the primary slurry feed 100 and the secondary slurry feed 200 into the flotation cell 1 may help in minimizing the build-up of sediment at the bottom 110 of the flotation cell 1. Therefore no special solutions, such as conical, slanting or funnel-like bottom structures may be required, as may be the case in conventional fluidized bed flotation cells. Further, it may be possible to avoid arranging a cleaning hatch or other maintenance constructions at the bottom 110 of the flotation cell 1, thereby making its constructions easier and more cost-effective. Naturally also the need of performing maintenance operations may be decreased, thereby reducing operational costs.

[0129] The flotation cell 1 as defined above may be used in recovering a valuable material suspended in slurry. In a further embodiment, the use is specifically directed to recovering particles comprising copper from low grade ore.

[0130] According to another aspect of the invention, the method for treating particles suspended in slurry and for separating the slurry into underflow 400 and overflow 500 in a flotation cell 1 as described above comprises feeding a primary slurry feed 100 comprising fresh slurry into the flotation cell 1 via a first feed inlet 14; and feeding a secondary slurry feed 200 comprising at least slurry recirculated from a flotation cell 1, 2 into the fluidized bed 10 via a second feed inlet 15 so as to contribute to the formation of the fluidized bed F, the slurry recirculated from the flotation cell 1 at a third position R between the recovery launder 24 and the tailings outlet 12.

[0131] The primary slurry feed 100 may be fed at the centre C of the flotation cell 1, so that the primary slurry feed 100 is distributed evenly around the centre C. The primary slurry feed 100 may be fed into the flotation cell 1 so that it has a flow direction counter-current to the rising bubble-particle agglomerates, for example by a sparger, as explained above. Alternatively, the primary slurry feed 100 may be fed into the flotation cell 1 from its perimeter 16 so that the primary slurry feed has a flow direction substantially perpendicular to the rising bubble-particle agglomerates. The primary slurry feed may be arranged to be fed on top of the fluidized bed 10, in the froth layer 25.

[0132] The secondary slurry feed 200 may be fed into the fluidized bed 10 so that it has a flow direction counter-current to the rising bubble-particle agglomerates. In an alternative embodiment, the secondary slurry feed 200 is fed into the fluidized bed 10 from the perimeter 16 of the flotation cell 1 so that it has a flow direction substantially perpendicular to the rising bubble-particle agglomerates. In yet another alternative embodiment, the secondary slurry feed 200 is fed into the fluidized bed 10 so that it has a flow direction concurrent with the rising bubble-particle agglomerates.

[0133] The embodiments described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment. A flotation cell, a use or a method, to which the disclosure is related, may comprise at least one of the embodiments described hereinbefore. It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.