EP2572778B1 - Flotation machine with dispenser nozzle and method for its operation - Google Patents

Description

The invention relates to a flotation machine equipped with at least one dispersing nozzle, to a method for operating the flotation machine and to the use thereof.

The flotation machine comprises a dispersing nozzle for dispersing a liquid further comprising at least one gas, comprising a gas feed nozzle and a tubular mixing arrangement, which has an inlet region for the at least one gas and the liquid and an outlet region for a gas formed from the at least one gas and the liquid. Has liquid mixture.

Dispergierdüsen of the type mentioned are already used in flotation machines, see DE 32 11 906 C2 or CA 2 462 740 A1 and EP 2 308 601 A1 ,

The GB 355,211 discloses a flotation process employing a dispersing nozzle into which air is introduced, whereby suspension is drawn into the dispersing nozzle. The US 5,816,446 describes a device for mixing two liquids to prepare a working solution, such as a cleaning solution, from a liquid concentrate and water.

Flotation is a physical separation process for separating fine-grained mixtures of solids, such as ores and gangue, in an aqueous slurry by means of air bubbles due to a different surface wettability of the particles contained in the suspension. It is used for the treatment of mineral resources and in the processing of preferably mineral substances with a low to moderate content of a useful component or a valuable material, for example in the form of non-ferrous metals, iron, metals of rare earths and / or precious metals and non-metallic minerals.

Flotation machines are already well known. The WO 2006/069995 A1 describes a flotation machine with a housing which comprises a flotation chamber, with at least one dispersing nozzle, here referred to as ejector, further with at least one gassing device, when using air aeration devices or aerators called, and a collecting container for a foam product formed in the flotation.

In the case of flotation or pneumatic flotation, a suspension of mostly water and fine-grained solid, mixed with reagents, is generally introduced into a flotation chamber. The purpose of the reagents is to ensure that, in particular, the valuable particles, which are preferably to be separated off, are rendered hydrophobic in the suspension. Simultaneously with a suspension, the at least one dispersing nozzle is supplied with gas, in particular air or nitrogen, which comes into contact with the hydrophobic particles in the suspension. By means of a gassing additional gas is introduced into the suspension. The hydrophobic particles adhere to forming gas bubbles, so that the gas bubble structures, also called aeroflocs, float and form the foam product on the surface of the suspension. The foam product is discharged into a collecting container and usually thickened.

It has been shown that the quality of the foam product or the separation success of the process of flotation or pneumatic flotation depends inter alia on the probability of collision between a hydrophobic particle and a gas bubble. The higher the probability of collision, the greater the number of hydrophobic particles that adhere to a gas bubble, rise to the surface and together with the particles form the foam product. The collision probability is among other things influenced by the dispersion of suspension and gas in a dispersing nozzle.

In the field of flotation plants, dispersing nozzles are not only used to supply gas and suspension as a mixture to a flotation chamber. They are also used to disperse liquids with or without a very small proportion of solids with gas and to inject the mixture into the liquid or suspension contained in the flotation machine.

There is a continuing need for low-wear facilities for the fumigation of liquids, especially suspensions, available with which very small gas bubbles can be generated.

It is firstly an object of the invention to provide a flotation machine comprising a dispersing nozzle to increase a proportion of gas bubbles in a liquid and to provide a method of operating such a flotation machine with a dispersing nozzle.

It is another object of the invention to provide a flotation machine with a higher yield and to provide a method for their operation.

The object is firstly achieved by a flotation machine comprising a housing with a flotation chamber and at least one dispersing nozzle for dispersing a liquid with at least one further gas, comprising a gas feed nozzle and a tubular mixing arrangement having a common inlet region for the at least one gas and the liquid Exit region for a gas-liquid mixture formed from the at least one gas and the liquid, wherein the mixing arrangement adjoins the Gaszuführdüse, the Gaszuführdüse tapers in the direction of the mixing assembly and opens into the inlet region, wherein the mixing assembly in the inlet region at least a number N ≥ 3 at suction openings for the liquid, wherein the suction openings are arranged perpendicular or at an angle to a longitudinal central axis of the dispersing, wherein a ratio of a diameter D _{G of} a gas outlet opening of the gas supply and an inner diameter D _{M of} the mixing arrangement in the inlet region in Range of 1: 3 to 1: 5, and wherein the gas supply nozzle is associated with at least one gas control valve for metering a gas amount of the at least one gas to be supplied to the liquid, wherein the liquid is a suspension, wherein the at least one dispersing nozzle opens into the flotation.

The dispersing nozzle allows an intensive introduction of gas into a suspension, wherein particularly small gas bubbles with diameters of <1 mm can be produced with little wear. In particular, a gassing of a suspension already in a container or the like is possible. The suspension is sucked into the interior of the mixing arrangement via the suction opening (s). On pumps which promote the suspension under pressure in the mixing arrangement, can be advantageously omitted here.

The intensive mixing of gas and liquid within the mixing arrangement of the dispersing nozzle is comparable to mixing in a conventional dispersing nozzle, via which, however, both gas and liquid are supplied. The dispersing nozzle makes it possible to increase the proportion of gas without at the same time increasing the proportion of liquid to be fumigated. Thus, the dispersing nozzle is particularly suitable for achieving an increase in the probability of collision between gas bubbles and hydrophobic particles in flotation machines.

In the case of dispersion of the gas with a suspension is due to the design of the dispersing the wear in comparison with conventional dispersing, via which a flotation machine simultaneously suspension and gas under high pressure, significantly reduced, especially in the area of the suspension feed. On the previously required, wear-prone pumps over which a flotation machine simultaneously suspension and gas were supplied under high pressure, can be completely dispensed with in the dispersing.

According to the invention, a ratio of a diameter D _{G of} a gas outlet opening of the gas feed nozzle and an inner diameter D _{M of} the mixing arrangement in the inlet region of the mixing arrangement is in the range from 1: 3 to 1: 5, in particular in the range from 1: 3 to 1: 3.5.

Due to the resulting strong expansion of the gas in the mixing arrangement, a particularly intensive mixing of the gas with the suspension is achieved.

The Gaszuführdüse is associated with at least one gas control valve for metering a gas quantity of the at least one gas to be supplied to the liquid in order to influence the ratio of gas and liquid in the mixing arrangement and the speed of the gas in the gas outlet opening.

It is advantageous if the mixing arrangement, starting from the gas feed nozzle, is subdivided successively into a mixing chamber which comprises the inlet region, a mixing tube and furthermore a diffuser whose diffuser diameter widens starting from the mixing tube and which comprises the outlet region. The mixing chamber has here the at least one suction opening for liquid.
Alternatively, the mixing arrangement can be subdivided, starting from the gas feed nozzle, successively into a mixing tube which comprises the inlet area and furthermore a diffuser whose diffuser diameter widens starting from the mixing tube and which comprises the outlet area. The mixing tube has here the at least one suction opening for liquid.

Preferably, a mechanical connection between the Gaszuführdüse and the mixing chamber or the mixing tube by means of at least one connecting element, which is arranged outside or at the periphery of the gas supply and the mixing arrangement.

An inner diameter of the mixing tube is either the same size for both embodiments or tapers in the direction of the diffuser.

The diffuser is formed curved in a preferred embodiment of the invention. This is advantageous in terms of the space requirement of the dispersing nozzle and leads to the formation of a swirling flow of the gas-liquid mixture formed, which brings about a further improvement in the dispersion of gas and liquid.
A ratio of a diameter D _{MR of} a mixing tube inlet opening of the mixing tube and a length L _{MR of} the mixing tube is preferably in the range from 1: 3 to 1: 8, in particular in the range from 1: 4 to 1: 6.

In an alternative embodiment, the inlet area of the mixing arrangement has at least a number N ≥ 8 of suction openings through which liquid can be sucked into the interior of the mixing arrangement. This allows a more uniform and faster mixing of the liquid with the gas flowing from the gas supply nozzle.

Suction openings are preferably formed with a circular, rectangular or slit-shaped outline. Preferably, a hole diameter of circular suction openings is formed as a function of the wall thickness of the mixing arrangement in the inlet region. In particular, the hole diameter is chosen to be greater than or equal to the wall thickness.

The suction opening (s) is / are preferably arranged perpendicular to a longitudinal central axis of the dispersing nozzle, but alternatively An arrangement at an angle to the longitudinal central axis is also possible.

Preferably, a plurality of suction openings are arranged at a uniform distance from one another centered on at least one circular path about the longitudinal center axis of the dispersing nozzle in order to achieve the most uniform all-round supply of liquid to the gas.

The gas supply nozzle tapering in the direction of the mixing arrangement preferably has an inner wall which is oriented at an angle α in the range from 3 ° to 15 °, in particular at an angle α in the range from 4 ° to 6 °, to the longitudinal central axis of the dispersing nozzle. The speed of the gas and the gas pressure in the region of the gas outlet opening are thereby increased.

The dispersing nozzle is preferably used for gassing liquids such as water, waste water, process water, etc. In particular, a dispersing nozzle is used for gassing liquids in the form of suspensions in flotation processes.

The object is further achieved by a method for operating a flotation machine according to the invention by introducing at least one gas into the mixing arrangement in its inlet region via the gas feed nozzle by sucking liquid into the interior of the mixing arrangement into its inlet region via the suction openings by introducing into the mixing arrangement Gas-liquid mixture is formed and a gas supply via the Gaszuführdüse such that the at least one gas at a gas outlet opening of the Gaszuführdüse with a pulse current density in the range of 5 _* 10 ³ to 5 _* 10 ⁴ kg / (m * s ² ) is present , wherein the liquid is a suspension.

As a result, a particularly intensive and uniform dispersion of gas and liquid is achieved, predominantly a preferred bubble diameter of <1 mm of the dispersed gas is achieved.

Particularly preferably, the pulse current density is in the range of 1 _* 10 ⁴ to 5 _* 10 ⁴ kg / (m _* s ² ), but especially in the range of 3 _* 10 ⁴ to 5 _* 10 ⁴ kg / (m _* s ² ).

For the method, it has proven useful, if the mixing arrangement comprises a mixing tube, for the gas-liquid mixture at a mixing pipe outlet opening to have a shear rate in the range from 500 to 5000 l / s, in particular from 1000 to 1500 l / s. The higher the shear rate, the smaller the gas bubbles generated in the gas-liquid mixture. This further improves the dispersion of gas and liquid.

The use of one or more dispersing nozzles on a flotation machine allows intensive mixing of gas into a liquid already present in the flotation machine without introducing further liquid into the flotation machine via the dispersing nozzle (s). As a result, the proportion of gas in the liquid can be increased considerably. The probability of collision between a gas bubble and a particle to be separated from a suspension increases and the yield is increased, the liquid being a suspension.

The flotation machine comprises a housing with a flotation chamber into which the at least one dispersing nozzle opens.

In this case, the mixing arrangement including the suction openings is arranged in particular in the flotation chamber, so that the mixing arrangement is surrounded by suspension and liquid can pass through the suction openings easily and without any auxiliary structures into the interior of the mixing arrangement. There is a gas enrichment in the flotation chamber contained liquid, without multiplying or diluting them.

Alternatively, the mixing arrangement can also be arranged outside the flotation chamber, although liquid must be conducted to the suction opening (s), for example via an additional pipeline or the like. In this case, liquid in the form of water, process water, suspension, etc., in particular of suspension from the flotation chamber, can be conducted to the suction openings. In the case of a dispersion of water or process water with the gas and an injection into the flotation of a flotation machine containing a suspension, the suspension is of course diluted by the additional water or process water. In the case of a dispersion of further suspension with the gas and an injection into the flotation chamber of a flotation machine containing a suspension, the suspension is of course increased by the further suspension. The achievable number of gas bubbles per unit volume of liquid is thus lower for these cases.

The object is achieved for a method for operating a flotation machine according to the invention by filling the flotation chamber with liquid such that the suction openings of the at least one dispersing nozzle are located below a surface formed by the liquid, wherein the liquid is a suspension.

The at least one existing dispersing nozzle is preferably operated according to the above-described method of operating the dispersing nozzle according to the invention.

The flotation chamber is filled in particular with a suspension having a solids content in the range from 30 to 60%. Such solids contents of suspensions are common, especially in the flotation of ore-containing minerals. A use of a flotation machine according to the invention for segregating an ore of gait has thus proved successful. However, the flotation machine can also be used in other ways, for example in the flotation of waste water, of suspensions containing other minerals containing ore, for example carbonaceous rock, etc.

FIG 1

eine erste Dispergierdüse im Längsschnitt;

FIG 2

einen vergrößerten Ausschnitt aus der ersten Dispergierdüse im Bereich der Gaszuführdüse;

FIG 3

das Funktionsprinzip einer Dispergierdüse mit gekrümmtem Diffusor;

FIG 4

eine zweite Dispergierdüse mit gekrümmtem Diffusor in einer Seitenansicht; und

FIG 5

eine Flotationsmaschine im Teillängsschnitt mit einer Dispersionsdüse.

The FIGS. 1 to 5 Dispersing nozzles according to the invention and their use as well as their use in flotation machines according to the invention are to be explained by way of example. So shows:

FIG. 1

a first dispersing nozzle in longitudinal section;

FIG. 2

an enlarged section of the first dispersing nozzle in the region of the gas supply nozzle;

FIG. 3

the operating principle of a dispersing nozzle with a curved diffuser;

FIG. 4

a second dispersing nozzle with curved diffuser in a side view; and

FIG. 5

a flotation machine in partial longitudinal section with a dispersion nozzle.

FIG. 1 shows in longitudinal section a first dispersing 1 for dispersing a liquid 6, in particular suspension 6 ', further comprising at least one gas 7. The first dispersing 1 comprises a Gaszuführdüse 2 with a gas outlet opening 2a and a tubular mixing assembly 3, which has an entry area for the at least one Gas 7 and the liquid 6 or suspension 6 'and an outlet region 1a for a from the at least one gas 7 and the liquid 6 or suspension 6' formed gas-liquid mixture 8 has. The gas feed nozzle 2 is preceded by at least one gas control valve, not shown here for the sake of clarity, for metering a gas quantity of the gas 7 to be supplied to the liquid 6. The mixing arrangement 3 follows the Gaszuführdüse 2 on. The gas feed nozzle 2 tapers in the direction of the mixing arrangement 3 and opens into its inlet region. The mixing arrangement 3 further has in the inlet area a plurality of suction openings 4 for the liquid 6 or suspension 6 '. The suction openings 4 are arranged here perpendicular to a longitudinal central axis 9 of the first dispersing nozzle 1. The mixing arrangement 3 in this embodiment, starting from the gas feed nozzle 2, successively into a mixing chamber 3a, which comprises the inlet region, a mixing tube 3b with a Mischrohraustrittsöffnung 5 and further a diffuser 3c, the diffuser diameter expands starting from the mixing tube 3b and which comprises the outlet region 1a , divided. However, the mixing chamber 3a and the mixing tube 3b can also be formed in one piece. Alternatively, the mixing tube 3b and the diffuser 3c or else the mixing chamber 3a, the mixing tube 3b and the diffuser 3c may be integrally formed.

FIG. 2 shows an enlarged section of the first dispersing 1 according to FIG. 1 in the area of the gas feed nozzle 2. Same reference numerals as in FIG FIG. 1 identify similar elements. The gas supply nozzle 2 here has an inner wall which is oriented at an angle α of 4 ° to the longitudinal central axis 9 of the first dispersing nozzle 1. A ratio of a diameter D _{G of} the gas outlet opening 2a of the gas feed nozzle 2 and an inner diameter D _{M of} the mixing arrangement 3 in the inlet region, here simultaneously the inner diameter of the mixing chamber 3a, is approximately 1: 3 to 1: 5.

A ratio of a diameter D _{MR of} a mixing tube inlet opening of the mixing tube 3b and a length L _{MR of} the mixing tube 3b is approximately 1: 5.

FIG. 3 shows the principle of operation of a dispersing nozzle with a mixing arrangement 3 with curved diffuser 3c. Same reference numerals as in FIG. 1 identify similar elements. A curved diffuser 3c reduces the dimensions of the dispersing nozzle and allows its use even in confined spaces spatial conditions. The formed gas-liquid mixture 8 a swirling motion is impressed, which leads to a further improvement of the dispersion of gas 7 and liquid 6 or suspension 6 '.

FIG. 4 shows a second dispersing nozzle 1 'with curved diffuser 3c in a side view. The same reference numerals as in FIGS. 1 and 3 designate the same elements.

FIG. 5 shows a flotation machine 100 with a known per se construction in partial longitudinal section, the right half is shown cut. The flotation machine 100 comprises a housing 101 with a flotation chamber 102 into which at least one conventional dispersing nozzle 10 for supplying gas 7 and suspension 6 'opens into the flotation chamber 102. The installation of conventional dispersing nozzles 10 is usually carried out in such a way that the longitudinal axis of the dispersing nozzle (s) 10 is aligned horizontally. The housing 101 has a cylindrical housing section 101a, at the lower end of which a gassing arrangement 103 is optionally arranged.

Within the flotation chamber 102 is a foam channel 104 with nozzle 105 for discharging the foam product formed. The upper edge of the outer wall of the housing 101 is located above the upper edge of the foam channel 104, whereby an overflow of the foam product on the upper edge of the housing 101 is excluded. The housing 101 further has a bottom discharge opening 106. Particles of the suspension 6 ', which are provided, for example, with an insufficiently hydrophobized surface or have not collided with a gas bubble, and hydrophilic particles sink in the direction of the bottom discharge opening 106 and are discharged. The foam product passes from the flotation chamber 102 in the foam channel 104 and is discharged via the nozzle 105 and optionally thickened.

The installation of dispersing nozzles 1,1 ', via which only gas 7 is introduced into the flotation chamber 102, which is dispersed with suspension 6' already present in the flotation chamber 102, preferably takes place here in such a way that the longitudinal central axis 9 of the dispersing nozzle 1, 1 'is aligned horizontally. But also an arrangement of dispersing nozzles 1,1 'on the flotation machine 100 at an angle of the longitudinal central axis 9 to the horizontal is possible.

By means of the optional gassing device 103, which is connected to a gas feed 103a, additional gas 7 is optionally blown into the cylindrical housing section 101a, so that further hydrophobic particles are bound thereto and rise. Ideally, especially the hydrophilic particles continue to sink and are discharged via the bottom discharge opening 106.

By using at least one dispersing nozzle 1, 1 ', for example with a curved diffuser, in the flotation machine 100, the dispersion of suspension 6' and gas 7 is further improved, thus increasing the probability of collision between a gas bubble and a particle to be separated from the suspension 6 '. As a result, increased deposition rates and an optimal foam product can be achieved. A curved construction of the mixing arrangement 3 as a whole is space-saving and therefore also optimally usable in the interior of a flotation chamber with a small diameter.

However, the use of a dispersing nozzle is not general to a flotation machine according to the invention or a flotation machine having a structure according to FIG. 5 limited. A dispersing nozzle can be used in flotation systems of any structure or equipment in which at least one gas is to be finely and evenly distributed in a liquid. Of course, the dispersing nozzle can thus be used regardless of a preferred application in flotation machines for fumigation of water, sewage, process water, etc.

Claims (20)

1. Flotation machine (100) comprising a housing (101) having a flotation chamber (102) and at least one dispersion nozzle (1, 1') for dispersing a liquid (6), also having at least one gas (7), said dispersion nozzle (1, 1') comprising a gas feed nozzle (2) and a tubular mixing arrangement (3) which has an inlet region for the at least one gas (7) and the liquid (6) and an outlet region (1a) for a gas/liquid mixture (8) formed from the at least one gas (7) and the liquid (6), the mixing arrangement (3) adjoining the gas feed nozzle (2), the gas feed nozzle (2) tapering in the direction of the mixing arrangement (3) and opening into its inlet region, the mixing arrangement (3) having at least a number N ≥ 3 of intake openings (4) for the liquid (6) in the inlet region, the intake openings (4) being disposed perpendicular to or at an angle to a longitudinal centre axis (9) of the dispersion nozzle (1, 1'), a ratio of a diameter D_G of a gas outlet opening (2a) of the gas feed nozzle (2) and an internal diameter D_M of the mixing arrangement (3) in the inlet region being in the range from 1:3 to 1:5, and at least one gas regulating valve for metering a quantity of the at least one gas (7) to be fed into the liquid (6) being assigned to the gas feed nozzle (2), the liquid being a suspension (6'), the at least one dispersion nozzle (1, 1') opening into the flotation chamber (102).
2. Flotation machine according to claim 1, the mixing arrangement (3) being divided successively from the gas feed nozzle (2) into a mixing chamber (3a), which comprises the inlet region, a mixing tube (3b) and also a diffuser (3c), the diffuser diameter of which increases from the mixing tube (3b) and which comprises the outlet region (1a).
3. Flotation machine according to claim 1, the mixing arrangement (3) being divided successively from the gas feed nozzle (2) into a mixing tube (3b), which comprises the inlet region, and also a diffuser (3c), the diffuser diameter of which increases from the mixing tube (3b) and which comprises the outlet region (1a).
4. Flotation machine according to one of claims 2 or 3,
   a ratio of a diameter D_MR of a mixing tube inlet opening of the mixing tube and a length L_MR of the mixing tube being in the range from 1:3 to 1:8.
5. Flotation machine according to one of claims 2 or 3, the diffuser (3c) being configured as curved.
6. Flotation machine according to one of claims 1 to 5, the inlet region having at least a number N ≥ 8 of intake openings (4).
7. Flotation machine according to one of claims 1 to 6,
   the intake openings (4) being disposed at a regular distance from one another on at least one circular path centred around the longitudinal centre axis (9) of the dispersion nozzle (1, 1').
8. Flotation machine according to one of claims 1 to 7, the gas feed nozzle (2), which tapers in the direction of the mixing arrangement (3), having an internal wall, which is aligned at an angle α in the range from 3° to 15°, in particular at an angle α in the range from 4° to 6°, to the longitudinal centre axis (9) of the dispersion nozzle (1, 1').
9. Flotation machine according to one of claims 1 to 8, the intake openings (4) having a circular hole diameter.
10. Flotation machine according to claim 9, the hole diameter being greater than or equal to a wall thickness of the mixing arrangement (3) in the inlet region.
11. Method for operating a flotation machine (1, 1')
    according to one of claims 1 to 10, at least one gas (7) being conducted into the mixing arrangement (3) by way of the gas feed nozzle (2) in its inlet region, liquid (6) being sucked into the interior of the mixing arrangement (3) by way of the at least one intake opening (4) in its inlet region, a gas/liquid mixture (8) being formed in the mixing arrangement (3) and gas being fed in by way of the gas feed nozzle (2) in such a manner that the at least one gas (7) is present at a gas outlet opening (2a) of the gas feed nozzle (2) with a pulsed flow density in the range from 5_*10³ to 5_*10⁴ kg/(m_*s²), the liquid being a suspension (6').
12. Method according to claim 11,
    characterised in that the pulsed flow density is in the range from 1_*10⁴ to 5_*10⁴ kg/(m_*s²).
13. Method according to claim 12,
    characterised in that the pulsed flow density is in the range from 3_*10⁴ to 5_*10⁴ kg/(m_*s²).
14. Method according to one of claims 11 to 13, the mixing arrangement (3) comprising a mixing tube (3b), a shear rate in the range from 500 to 5000 1/s, in particular from 1000 to 1500 1/s, being present for the gas/liquid mixture (8) at a mixing tube outlet opening (5).
15. Flotation machine according to one of claims 1 to 10, the mixing arrangement (3), including the intake openings (4), being disposed in the flotation chamber (102).
16. Flotation machine as claimed in one of claims 1 to 10 or 15, the longitudinal centre axis (9) of the at least one dispersion nozzle (1, 1') being aligned horizontally.
17. Method for operating a flotation machine (100) according to one of claims 1 to 10, 15 or 16, the flotation chamber (102) being filled with liquid (6), in such a manner that the intake openings (4) of the at least one dispersion nozzle (1) are below a surface formed by the liquid (6), the liquid being a suspension (6').
18. Method according to claim 17, the at least one dispersion nozzle (1, 1') being operated in accordance with a method according to one of claims 11 to 14.
19. Method according to one of claims 17 or 18, the flotation chamber (102) being filled with a suspension (6') with a solid material content in the range from 30 to 60%.
20. Use of a flotation machine (100) according to one of claims 1 to 10, 15 or 16 for separating an ore from gangue.

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