FLOTATION LINE

Abstract

A flotation line for treating mineral ore particles suspended in slurry is disclosed. The flotation line includes a rougher part with at least one rougher flotation cell from which overflow is arranged to flow directly into a cleaner flotation line; and a scavenger part with at least two scavenger flotation cells from which overflow is arranged to flow back into a rougher flotation cell, or into a regrinding step and then into a cleaner flotation line. Underflow from a last scavenger flotation cell is arranged to be removed from the flotation line as tailings. At least 75% of the flotation cells include a mechanical agitator including a system for introducing flotation gas into the flotation cell. At least one of the flotation cells of the flotation line includes a mechanical agitator including a microbubble generator for introducing microbubbles into the slurry.

Claims

1.-44. (canceled)

45. A flotation line for treating mineral ore particles suspended in slurry, comprising a rougher part with at least one rougher flotation cell for the separation of slurry into underflow and overflow with the help of flotation gas, the overflow from a rougher flotation cell arranged to flow directly into a cleaner flotation line; and a scavenger part with at least two scavenger flotation cells for the separation of slurry into underflow and overflow with the help of flotation gas, wherein overflow from a scavenger flotation cell is arranged to flow back into a rougher flotation cell of the rougher part of the flotation line, or into a regrinding step and then into a cleaner flotation line; underflow of each preceding flotation cell of the flotation line is directed to a subsequent flotation cell of the flotation line as infeed until a last flotation cell of the flotation line, the last flotation cell being a scavenger flotation cell the underflow of which is directed out of the line as tailings, at least 75% of the flotation cells in the flotation line comprise a mechanical agitator comprising a rotor, a stator, and a system for introducing flotation gas into the flotation cell; the flotation cells of the flotation line are connected in series and arranged in fluid communication; and wherein at least one of the flotation cells comprising a mechanical agitator comprises a microbubble generator for introducing microbubbles into the slurry, and that underflow from a previous flotation cell is arranged to be led into a subsequent flotation cell by gravity.

46. The flotation line according to claim 45, wherein overflows of the flotation cells comprise a concentrate, and underflows of the flotation cells are arranged to flow into the tailings.

47. The flotation line according to claim 45, wherein at least one of the flotation cells preceding the last flotation cell of the flotation line comprises a microbubble generator.

48. The flotation line according to claim 45, wherein all flotation cells preceding the last flotation cell of the flotation line comprise a microbubble generator.

49. The flotation line according to claim 45, wherein at least one of the scavenger flotation cells of the scavenger part of the flotation line comprises a microbubble generator.

50. The flotation line according to claim 45, wherein all of the scavenger flotation cells of the scavenger part of the flotation line comprise microbubble generators.

51. The flotation line according to claim 45, wherein the last flotation cell of the flotation line comprises a microbubble generator.

52. The flotation line according to claim 45, wherein the flotation line comprises at least three flotation cells, or 310 flotation cells, or 47 flotation cells.

53. The flotation line according to claim 45, wherein the rougher part comprises at least two rougher flotation cells, or 27 rougher flotation cells, or 25 rougher flotation cells.

54. The flotation line according to claim 45, wherein the scavenger part comprises at least two scavenger flotation cells, or 27 scavenger flotation cells, or 25 scavenger flotation cells.

55. The flotation line according to claim 45, wherein the first flotation cell of the flotation line is at least 25 m3 in volume, or at least 100 m3 in volume.

56. The flotation line according to claim 45, wherein a second flotation cell of the flotation line is at least 25 m3 in volume, or at least 100 m3.

57. The flotation line according to claim 45, wherein the height, measured as the distance between a flotation cell bottom and launder lip, to diameter, measured at the height of the mechanical agitator, ratio of a flotation cell is 1.5 or lower.

58. The flotation line according to claim 45, wherein the stator comprises a system for introducing flotation gas into the flotation cell.

59. The flotation arrangement according to claim 45, wherein flotation gas is fed into a preparation flotation cell into which the mechanical agitator is arranged, and the preparation flotation cell comprises a microbubble generator.

60. The flotation line according to claim 45, wherein the mineral ore particles comprise Cu, or Zn, or pyrite, or metal sulfide.

61. The flotation line according to claim 45, wherein the mineral ore particles comprise Cu from lowgrade ore.

62. The flotation line according to claim 45, wherein the first flotation cell is arranged to treat mineral ore particles having a D80 of at least 75 m.

63. The flotation line according to claim 45, wherein the first flotation cell is arranged to treat mineral ore particles having a D80 of less than 300 m.

64. The flotation line according to claim 63, wherein the last flotation cell is arranged to treat mineral ore particles having a D80 of less than 200 m.

65. The flotation line according to claim 45, wherein the microbubble generator is arranged to receive slurry from a bottom of a flotation cell via an outlet, and to return the slurry comprising microbubbles back into the flotation cell via at least one return inlet arranged above, in the vertical direction of the flotation cell, the outlet.

66. The flotation line according to claim 45, wherein the microbubble generator comprises a slurry recirculation system.

67. The flotation line according to claim 66, wherein the slurry recirculation system comprises a recirculation pump, arranged to intake slurry from a flotation cell via the outlet; a distribution unit, arranged to distribute slurry evenly within the recirculation system; a sparger assembly arranged to create microbubbles and cause attachment of microbubbles onto mineral ore particles in slurry, and further arranged to introduce the slurry back into the flotation cell via the return inlet; and a compressor or a blower arranged to feed compressed air/gas into the sparger assembly.

68. The flotation line according to claim 67, wherein the sparger assembly is arranged radially around the perimeter of the flotation cell.

69. The flotation line according to claim 45, wherein the microbubble generator comprises a direct sparger system.

70. The flotation line according to claim 69, wherein the direct sparger system comprises a sparger assembly, arranged radially around the perimeter of the flotation cell, and further arranged to introduce microbubbles directly into the slurry within the flotation cell.

71. The flotation line according to claim 70, wherein the sparger assembly comprises jetting spargers, or cavitation spargers, or Venturi spargers.

72. Use of a flotation line according to claim 45, wherein recovering mineral ore particles comprising a valuable mineral.

73. The use of a flotation line according to claim 72 in recovering mineral ore particles comprising a valuable mineral from low grade ore.

74. The use of a flotation line according to claim 73 in recovering mineral ore particles comprising Cu from low grade ore.

75. A flotation plant comprising a flotation line according to claim 45.

76. The flotation plant according to claim 75, wherein the plant comprises at least two, or at least three flotation lines.

77. The flotation plant according to claim 75, wherein a flotation line is arranged to recover mineral ore particles comprising Cu, and/or Zn, and/or pyrite, and/or a metal from a sulfide.

78. The flotation plant according to claim 75, wherein a flotation arrangement is arranged to recover mineral ore particles comprising Cu from low grade ore.

79. A method for treating mineral ore particles suspended in slurry, wherein the slurry is subjected to a rougher flotation stage with at least one rougher flotation step wherein slurry is separated into underflow and overflow with the help of a flotation gas; overflow from a rougher flotation step is led to flow directly into a cleaner flotation stage; underflow from the rougher flotation stage is led to a scavenger flotation stage with at least two scavenger flotation steps wherein slurry is separated into underflow and overflow with the help of a flotation gas; overflow from a scavenger flotation step is led to flow back into a rougher flotation step of the rougher flotation stage of the flotation line, or into a regrinding step and then into a cleaner flotation stage; the slurry is mechanically agitated using a mechanical agitator comprising a rotor, a stator, and a system for introducing flotation gas into a flotation cell in at least 75% of the flotation steps; the flotation steps are in series and have fluid communication; underflow from a previous flotation step is led into a subsequent flotation step; and overflow comprises a concentrate and underflow comprises tailings, wherein microbubbles are generated into the slurry in at least one of the flotation steps in which the slurry is mechanically agitated, and that underflow from a previous flotation step is led into a subsequent flotation step by gravity.

80. The method according to claim 79, wherein microbubbles are generated into at least one flotation step preceding the last flotation step.

81. The method according to claim 79, wherein microbubbles are generated into all flotation steps preceding the last flotation step.

82. The method according to claim 79, wherein microbubbles are generated in at least one scavenger flotation step of the scavenger flotation stage.

83. The method according to claim 79, wherein microbubbles are generated into all of the scavenger flotation steps of the scavenger flotation stage.

84. The method according to claim 79, wherein microbubbles are generated into the last flotation step.

85. The method according to claim 79, wherein microbubbles are generated by introducing slurry from a flotation step into a microbubble generator, and returning the slurry comprising microbubbles back into the flotation step.

86. The method according to claim 79, wherein the microbubbles are generated by recirculating the slurry.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] 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:

[0112] FIG. 1 illustrates a detail of an embodiment of the invention.

[0113] FIG. 2 is a simplified schematic illustration of a flotation line according to the invention.

[0114] FIGS. 3a and 3b are flow chart illustrations for embodiments of the invention.

[0115] FIG. 4 is a flow chart illustration for an embodiment of a flotation plant according to an embodiment of the invention.

DETAILED DESCRIPTION

[0116] Reference will now be made in detail to the embodiments of the present disclosure, an example of which is illustrated in the accompanying drawing.

[0117] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utilize the arrangement, plant and 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.

[0118] For reasons of simplicity, item numbers will be maintained in the following exemplary embodiments in the case of repeating components.

[0119] The enclosed FIGS. 2 and 3a, 3b illustrate a flotation line 10, and in FIG. 1, a flotation cell 110 is presented in some detail. The figures are not drawn to proportion, and many of the components of the flotation cell 110 and the flotation line 10 are omitted for clarity. The forward direction of flow of slurry is shown in the figures by arrows.

[0120] Although flotation is disclosed in the following examples by reference mostly to froth flotation, it should be noted that the principles according to the invention can be implemented regardless of the specific type of the flotation, i.e. the flotation technique can be any of the known per se flotation techniques, such as froth flotation, dissolved air flotation or induced gas flotation.

[0121] The basic operational principle of the flotation line 10 is presented in FIGS. 2 and 3a, 3b. The following description is to be read mainly in relation to those figures unless otherwise stated.

[0122] The flotation line 10 comprises a rougher part 11 with at least one rougher flotation cell 111a. From a rougher cell 111a, 111b overflow 51 is arranged to flow directly into a cleaner flotation line, which is a rougher cleaner flotation line. The flotation line 10 also comprises a scavenger part 12 with at least two scavenger flotation cells 112a, 112b. Overflow of a scavenger flotation cell 112a, 112b is arranged to flow back into a rougher flotation cell 111a, 111b (see FIG. 3b) or into a regrinding step 91 and then into a cleaner flotation line, which is a scavenger cleaner flotation line (see FIG. 3a). Underflow 40 from a flotation cell is arranged to be led into an adjacent flotation cell as infeed, i.e. a subsequent flotation cell is arranged to receive underflow 40 from a previous flotation cell. The flotation cells 111a-b, 112a-b are connected in series and arranged in fluid communication 500.

[0123] A first flotation cell 111a of the flotation line 10 receives a flow of suspension, that is, a slurry inflow 11 comprising ore particles, water and, in some instances, flotation chemicals such as collector chemicals and non-collector flotation reagents for separating the slurry into an underflow 40 and an overflow 50a. A typical flotation cell is presented in FIG. 1. The flotation cell comprises a mixer in the form of a mechanical agitator 70, for example a rotor 72stator 71 assembly, as is shown in FIG. 1, or any other suitable mixer for promoting the collisions between flotation gas bubbles and ore particles. In an embodiment, the stator 71 comprises a system or assembly for introducing flotation gas into the flotation cell 110, 111a-b, 112a-b.

[0124] In an embodiment, flotation gas may be fed or introduced into the flotation cell where the slurry is separated into overflow and underflow. In an embodiment, flotation gas may be fed into a part of the flotation cell into which a mixer is arranged, i.e. into a preparation flotation cell preceding a flotation cell in which the ore particles are floated and thus separated into overflow and underflow. In this embodiment, the preparation flotation cell comprises a microbubble generator 60.

[0125] At least 75% of the flotation cells 111a-b, 112a-b of the flotation line comprise a mechanical agitator 70.

[0126] In a flotation process with flotation chemicals, a process of froth flotation takes place: the collector chemical molecules adhere to surface areas on ore particles having the valuable mineral, through an adsorption process. The valuable mineral acts as the adsorbent while the collector chemical acts as the adsorbate. The collector chemical molecules form a film on the valuable mineral areas on the surface of the ore particle. The collector chemical molecules have a non-polar part and a polar part. The polar parts of the collector molecules adsorb to the surface areas of ore particles having the valuable minerals. The non-polar parts are hydrophobic and are thus repelled from water. The repelling causes the hydrophobic tails of the collector molecules to adhere to flotation gas bubbles. An example of a flotation gas is atmosphere air pumped to flotation cell. A sufficient amount of adsorbed collector molecules on sufficiently large valuable mineral surface areas on an ore particle may cause the ore particle to become attached to a flotation gas bubble. It is also conceivable that the flotation process may be performed without flotation chemicals. In the following, the examples are disclosed in view of conventional flotation.

[0127] Ore particles become attached or adhered to gas bubbles to form gas bubble-ore particle agglomerates. These agglomerates rise to the surface of the flotation cells 110, 111a-b, 112a-b at the uppermost part or top part 130 of the cell 110 by buoyancy of the gas bubbles, as well as with the continuous upwards flow of slurry which may be induced by both mechanical agitation and the infeed of slurry into the cell 110a-d.

[0128] The gas bubbles form a layer of froth or forth zone at the top part 130 of the flotation cell 110. Froth gathered to a surface of slurry in the flotation cell 110, 111a-b, 112a-b, comprising the gas bubble-ore particle agglomerates is let to flow out of flotation cell, over a launder lip 21 and into a launder 20.

[0129] From the surface of the slurry at the top part 130 of the flotation cell 110a-d, the valuable mineral containing ore particles overflow the launder lip 21 of the flotation cell to be collected into the launder 20.

[0130] The valuable mineral containing ore particles overflowing the launder lip 21 is called primary overflow 50a-d. By a launder lip 21 is herein meant the peripheral edge of a flotation cell 110a-d at the upper part 112 of the cell over which froth overflow with valuable material particles flows to the launder 20.

[0131] Overflows 51, 52 from the flotation line 10 are recovered as a concentrate 81. The concentrate 81 of ore particles comprising valuable mineral is in a form of a fluid which may be led to further treatment. In an embodiment (see FIG. 3a), some or all of the overflows 52 from the scavenger part 12 of the flotation line 10 may be led directly into a regrinding step 91, followed by a subsequent flotation step comprising a cleaner flotation line, i.e. a cleaning circuit comprising a number of cleaner flotation cells (not shown in the figures). In an embodiment (see FIG. 3b), some or all of the overflows 52 from the scavenger part 12 may be led back into a rougher flotation cell 111a, 111b, to be treated again in the flotation line 10. Overflow 52 from one or more scavenger flotation cells 112a-b may be led back into a rougher flotation cell 111a, 111b, and at the same time, overflow 52 from other scavenger flotation cells 112a-b may be led directly to the regrinding step 91 (this embodiment is not shown in the figures). It is clear to a person skilled in the art, that any combination of arranging overflows 52 from the scavenger part 12 in the above-described manner is conceivable, according to the specific construction and use of the flotation line 10, even though only two specific embodiments are shown in FIGS. 3a and 3b.

[0132] From the area located close to a flotation cell bottom 120, a gangue or a part of the slurry containing ore particles that do not rise onto the surface of the slurry is led out of the rougher flotation cell 111a as underflow 40. Underflow 40 is led into a subsequent rougher flotation cell 111b (or a subsequent scavenger flotation cell 112a, see FIG. 2) that receives underflow 40 as an infeed from the previous rougher flotation cell 111a. The slurry is treated in the subsequent primary flotation cell 110b similarly as in the first primary flotation cell 110a, in a manner well known to a person skilled in the art.

[0133] The flotation line 10 may comprise at least three flotation cells 111a-b, 112a-b. Alternatively, the flotation line may comprise 3-10 flotation cells 111a-b, 112a-b. Alternatively, the flotation line 10 may comprise 4-7 flotation cells 111a-b, 112a-b. The rougher part 11 may comprise at least two rougher flotation cells 111a-b. Alternatively, the rougher part 11 may comprise 2-7 rougher flotation cells 111a-b. Alternatively, the rougher part 11 may comprise 2-5 rougher flotation cells 111a-b. Additionally or alternatively, the scavenger part 12 may comprise at least two scavenger flotation cells 112a-b, or 2-7 scavenger flotation cells 112a-b, or 2-5 scavenger flotation cells 112a-b.

[0134] The flotation cells 111a-b, 112a-b are connected in series and arranged in fluid communication 500. The fluid connection may be realized by a conduit (pipe or tube, as is shown in the figures) so that the neighboring flotation cells are arranged at a distance from each other. Alternatively, the at least two flotation cells 111a-b, 112a-b may be arranged into direct cell connection so that no separate conduit between the two flotation cells is needed (not shown in figures). In embodiments of the invention, where the flotation line 10 comprises more than two flotation cells, all of the adjacent or subsequent flotation cells of the flotation line 10 may be arranged into fluid connection 500 with conduits arranged between the flotation cells for directing underflow 40 from one flotation cell to the next flotation cell.

[0135] Alternatively, all of the flotation cells may be arranged into direct cell connection with the neighboring flotation cells. Alternatively, some of the adjoining flotation cells may arranged in direct cell connection with the neighboring flotation cells, while other neighboring flotation cells may have a conduit for realizing the fluid connection 500. The arrangement and design of the flotation line 10 may depend on the overall process requirements and physical location of the flotation line 10.

[0136] From the last flotation cell 112b of the flotation line 10, underflow 40 or reject is led out of the flotation line 10 as tailings 83.

[0137] The first flotation cell 111a of the flotation line 10 is at least 25 m.sup.3 in volume. Alternatively, the first primary flotation cell 100a may be at least 100 m.sup.3 in volume.

[0138] The second flotation cell 111b, or any one of the subsequent flotation cells 111b, 112a-b downstream of the first flotation cell 111a, is at least 25 m.sup.3 in volume. Alternatively, the second flotation cell 111b, or any one of the subsequent flotation cells 111b, 112a-b downstream of the first flotation cell 111a, may be at least 100 m.sup.3 in volume.

[0139] The flotation cells 111a-b, 112a-b are constructed to have certain dimensions. More specifically, a flotation cell has a height h, measured as the distance between the cell bottom 120 and the launder lip 21 (see FIG. 1); and a diameter D, measured at the height of the mechanical agitator 70. Typically, the cross-section of a flotation cell may be circular. In that case the diameter D is self-explanatory. However, the cross-section of a flotation may also be, for example, rectangular, square, triangular, hexagonal, pentagonal or other polygonal cross-sections, the form of the flotation cell cross-section defined by the side wall or walls of the flotation cell. In that case, the diameter D is to be understood as the maximum width of the flotation cell, measured from side wall-to-side wall at the height of the mechanical agitator 70. In an embodiment, the height h to diameter D ratio of the flotation cell is 1.5 or lower. In further embodiments, the h/D ratio may be 0.5; or 0.75; or 1.0; or 1.3.

[0140] Flows of slurry, both underflows 40 and overflows 51, 52 may be arranged to be driven by gravity. That is, any flow between any at least two flotation cells in fluid connection may be driven by gravity. For example, the underflow 40 flow of slurry between the first rougher flotation cell 111a and a further rougher flotation cell 111b or a scavenger flotation cell 112a may be driven by gravity.

[0141] To facilitate the movement by gravity of flows of slurry, at least some of the flotation cells 111a-b, 112a-b may be arranged in a stepwise fashion in relation to the ground level on which the flotation arrangement is established (see FIG. 2). Alternatively or additionally, the launder lips 21 of the flotation cells 110a-c, may be arranged at different heights. A step realised in between any adjacent flotation cell causes a difference in the froth layer level or launder lip 21 level of the two adjacent flotation cells. The gravitational flow of slurry is achieved by the hydraulic gradient between any two flotation cells with different slurry surface levels, realized with a step between the flotation cell bottoms 111.

[0142] In FIG. 1, the some of the constructional details of a flotation cell 110 are shown. Apart from the above-described features, the flotation cell 110 may comprise a microbubble generator 60 for introducing microbubbles into the slurry. More specifically, in the flotation line 10, at least one of the flotation cells comprising a mechanical agitator 70 comprise a microbubble generator 60. In an embodiment, at least one of the flotation cells 111a-b, 112a preceding, in the direction of flow, the last flotation cell 112b of the flotation line 10 comprises a microbubble generator 60. In an embodiment, alternatively or additionally, all of the flotation cells 111a-b, 112a preceding the last flotation cell 112b of the flotation line 10 comprise a microbubble generator 60 (see FIGS. 3a, 3b). In an embodiment, alternatively or additionally, the last flotation cell 112b of the flotation line 10 comprises a microbubble generator (see FIG. 2).

[0143] In an embodiment, at least one of the scavenger flotation cells 112a, 112b of the scavenger part 12 of the flotation line 10 comprises a microbubble generator 60. In an embodiment, alternatively or additionally, all of the scavenger flotation cells 112a-b comprise microbubble generators 60.

[0144] In an embodiment, the microbubble generator 60 is arranged to receive slurry from the bottom or bottom part 120 of the flotation cell via an outlet 610 situated near the bottom 120 of the cell. The microbubble generator is further arranged to return the slurry comprising microbubbles back into the flotation cell via at least one return inlet 620 arranged above the outlet 610. Above is intended to mean a position higher up in the vertical direction of the flotation cell 110, and preferably (although not necessarily) a position outside the mixing zone in the immediate vicinity of the mechanical agitator and/or at the level of the mechanical agitator indicated by the line D in FIG. 1.

[0145] The microbubble generator 60 may comprise a slurry recirculation system 600. In an embodiment, the slurry recirculation system 600 comprises a recirculation pump 61 arranged to intake slurry from a flotation cell 110, 111a-b, 112a-b via the outlet 610; a distribution unit, such as a distribution box (not shown in the figures), arranged to distribute slurry evenly within the recirculation system 600; a sparger assembly 62 arranged to created microbubbles and cause attachment of microbubbles onto mineral ore particles in slurry, and further arranged to introduce slurry back into the flotation cell via the return inlet 620. The slurry recirculation system 600 further comprises a compressor or a blower (not shown in the figures) arranged to feed compressed air or gas into the sparger assembly 62. In an embodiment, the sparger assembly is arranged radially around the perimeter of the flotation tank. For example, the sparger assembly may comprise a number of radially placed spargers spaced evenly around the perimeter of the flotation tank.

[0146] In an embodiment, the microbubbles may be introduced into a flotation cell 110, 111a-b, 112a-b by a microbubble generator 60 comprising a direct sparger system. In a direct spargers system, slurry is not recirculated, but air/gas or air/gas and water is introduced directly into the flotation cell via a sparger assembly 62. In an embodiment, the direct sparger system comprises a sparger assembly 62 arranged radially and evenly around the perimeter of the flotation cell, and arranged to introduce microbubbles directly into the slurry within the flotation cell.

[0147] In all of the above embodiments, the sparger assembly may comprise a variety of spargers, for generating an appropriate microbubble size distribution by injecting air into the recirculated slurry, or directly to the slurry. 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 microbubbles 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. In addition, air may be injected to ensure good microbubble generation.

[0148] The flotation line 10 according to the invention is intended for treating mineral ore particles comprising copper (Cu), zinc (Zn), pyrite, or a metal sulfide. The flotation line 10 is especially intended for treating mineral ore particles comprising copper from low-grade ore.

[0149] The first flotation cell, that is, the first rougher flotation cell 111a is arranged to treat mineral ore particles having a D80 of at least 75 m. Alternatively or additionally, the first flotation cell, that is, the first rougher flotation cell 111a is arranged to treat mineral ore particles having a D80 of less than 300 m. Alternatively of additionally the last flotation cell, that is, the last scavenger flotation cell 112b is arranged to treat mineral ore particles having a D80 of less than 200 m.

[0150] The flotation line 10 described herein is particularly suitable for, but not limited to, use in recovering valuable mineral containing ores, where the mineral ore particles comprise Cu, Zn, pyrite, or a metal sulfide such as gold sulfide. The flotation line 10 is suitable for use in recovering mineral ore particles comprising a valuable mineral, particularly from low grade ore. The flotation line 10 is particularly suitable for recovering mineral ore particles comprising Cu from low grade ore.

[0151] According to a further aspect of the invention, a flotation plant 9 (see FIG. 4) may comprise a flotation line 10 arranged to recover Cu. Alternatively or additionally, the flotation plant 9 may comprise a flotation line 10 arranged to recover Zn. Alternatively or additionally, the flotation plant 9 may comprise a flotation line 10 arranged to recover pyrite. Alternatively or additionally, the flotation plant 9 may comprise a flotation line 10 arranged to recover a metal from a sulfide. According to a further embodiment of the invention, the flotation plant 9 may comprise a flotation line 10 arranged to recover mineral ore particles comprising Cu from low grade ore.

[0152] In an embodiment, the flotation plant 9 may comprise at least two, or at least three flotation arrangements 1 according to the invention.

[0153] According to an embodiment of the invention, the flotation plant 9 may comprise at least one first flotation line 10a for the recovery of a first concentrate 81, and at least one second flotation line 10b for the recovery of a second concentrate 82. In an embodiment, the flotation cells 111a-b, 112a-b of the at least one first flotation line 10a for the recovery of the first concentrate 81 and the flotation cells 111a-b, 112a-b of the at least one second flotation line 10b for the recovery of the second concentrate 82 are arranged in series. In that way, underflow 40 from the last flotation cell 112a of the first flotation line 10a is arranged to be led to the second flotation line 10b as an infeed 1.

[0154] The flotation plant 9 may further comprise an arrangement for further treating the mineral ore particles suspended in slurry so that the second concentrate 82 is different from the first concentrate 81. In an embodiment, the arrangement for further treating the mineral ore particles may be a grinding step 90 disposed between a first flotation line 10a and a second flotation line 10b. In an embodiment, the arrangement for further treating the mineral ore particles may be an arrangement 92 for the addition of flotation chemicals, disposed between a first flotation line 10a and a second flotation line 10b.

[0155] According to another aspect of the invention, a flotation method for treating mineral ore particles suspended in slurry is presented. In the method, slurry is subjected to a rougher flotation stage 11 with at least one rougher flotation step 111a, wherein slurry is separated into underflow 40 and overflow 51 with the help of flotation gas. Overflow 51 from a rougher flotation step 111a, 111b is led to flow directly into a cleaner flotation stage; underflow 40 from the rougher flotation stage is led to a scavenger flotation stage 12 with at least two scavenger flotation steps 112a, 112b wherein slurry is separated into underflow 40 and overflow 52 with the help of flotation gas; overflow 52 from a scavenger flotation step 112a, 112b is led to flow back into a rougher flotation step 111a, 111b of the rougher flotation stage 11, or into a regrinding step 91 and then into a cleaner flotation stage The slurry is mechanically agitated in at least 75% of the flotation steps which are in series and have fluid communication 500. Underflow 40 from a previous flotation step is led into a subsequent flotation step. Overflow 51, 52 comprises a concentrate 81 and underflow 40, 40 comprises tailings 83. In the method, microbubbles are generated into the slurry in at least one of the flotation steps in which the slurry is mechanically agitated.

[0156] In an embodiment, microbubbles are generated into at least one flotation step 111a-b, 112a preceding the last flotation step 112b. Alternatively or additionally, microbubbles may be generated into all flotation steps 111a-b, 112a preceding the last flotation step 112b.

[0157] In an embodiment, microbubbles are generated in at least one scavenger flotation step 112a of the scavenger flotation stage 12. Alternatively or additionally, microbubbles may be generated into all of the scavenger flotation steps 112a-b of the scavenger flotation stage 12. Alternatively or additionally, microbubbles may be generated into the last flotation step 112b.

[0158] In an embodiment, microbubbles may be generated by introducing slurry from a flotation step into a microbubble generator 60, and returning the slurry comprising microbubbles back into the flotation step.

[0159] In an embodiment, the microbubbles are generated by recirculating the slurry.

[0160] 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. An arrangement, a method, a plant or a use, 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.