EP2497575A1 - Flotation device with a gas diffuser made from a foam material - Google Patents

Abstract

The device (1) has a housing (2) with a flotation chamber (2a) for holding a suspension (S), and feed arrangements (3) for feeding gas (G) into the chamber. The arrangements comprise gas distributor elements (4) formed from open-pored materials. Surface regions of the distributor element are arranged in an area of the chamber that is moistened by the suspension. An open-pored material is formed by a foam material composed of metal or plastic. Baffle plates for discharging gas out of the distributor elements are arranged in a vertical direction above the distributor elements.

Description

The invention relates to a flotation device for separating solid particles from a suspension, comprising a housing with a flotation chamber for receiving the suspension and at least one feed arrangement for supplying gas into the flotation chamber, wherein the at least one feed arrangement comprises at least one gas distributor element which comprises at least one open-pore Material is formed, wherein at least one surface region of the gas distribution element is arranged in the region of the flotation chamber, that this is wetted by the suspension. The invention further relates to the use of such a flotation device.

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 mineral resources.

The WO 2006/069995 A1 describes a pneumatic flotation cell with a housing comprising a flotation chamber, with at least one nozzle arrangement for feeding suspension into the flotation chamber, here referred to as ejectors, furthermore with at least feed arrangement for supplying gas into the flotation chamber, when using air aeration devices or aerators , as well as one Collecting container for a foam product formed during flotation.

In pneumatic flotation, a suspension of water and fine-grained solid mixed with reagents is generally introduced into a flotation chamber via at least one nozzle arrangement. The purpose of the reagents is to ensure that, in particular, the valuable particles or valuable material particles, which are preferably to be separated off, are rendered hydrophobic in the suspension. In most cases, xanthates are used as reagents, in particular to selectively hydrophobize sulfidic ore particles. Simultaneously with the suspension, the at least one nozzle arrangement is supplied with gas, in particular with air, which comes into contact with the hydrophobic particles in 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.

The quality of the foam product or the separation efficiency of the flotation process 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.

A preferred diameter of the gas bubbles is less than about 5 mm and is in particular in the range between 1 and 5 mm. Such small gas bubbles have a high specific surface area and are therefore able to bind and take up significantly more valuable material particles, in particular ore particles, per amount of gas used than larger gas bubbles are capable of doing.

In general, gas bubbles larger in diameter increase faster than gas bubbles of smaller diameter. The smaller gas bubbles are collected by larger gas bubbles and combine with them to even larger gas bubbles. This reduces the available specific surface of the gas bubbles in the suspension, can be bound to the valuable particles.

In columnar flotation cells in which a diameter of the flotation chamber is many times smaller than its height, the path which a gas bubble must travel in the suspension or the flotation chamber in order to reach the surface of the suspension is particularly large. Due to the particularly long way, particularly large gas bubbles are formed in the suspension. This reduces the specific discharge of valuable particles from the suspension and thus also the efficiency of the flotation cell.

In so-called hybrid flotation cells, which represent a combination of a pneumatic flotation cell with a columnar flotation cell, larger particulate matter having particle diameters in the range of 50 microns and larger are not completely bound to the existing gas bubbles and thus can only be partially separated from the suspension. Fines with particle diameters in the range of 20 microns and less, however, are particularly well deposited.

To equalize the supply of the flotation chamber with gas, in the US 4,997,549 or even the US 4,744,890 proposed to let the suspension flow helically from top to bottom through the flotation chamber and further to limit the flotation chamber by a double-walled vessel with a porous inner wall through which gas is supplied to the suspension.

The JP 58189054 A describes a method and apparatus for coal flotation. Here comes a flotation device used, which has in the region of the flotation chamber a porous bottom plate made of ceramic, through which the suspension gas is supplied.

However, it has been shown that the pores of open-porous ceramic materials in the flotation chamber clog quickly with solid particles from the suspension and the gas pressure behind the ceramic material increases sharply. As a result of this and due to the further mechanical stresses in the flotation chamber, unwanted brittle fractures occur in the area of the ceramic materials used. A necessary replacement of the broken ceramic material is associated with an undesirable down time for the flotation device.

It is an object of the invention to provide a flotation device having an improved gas supply to the flotation chamber comprising open-porous material.

The object is for the flotation device for separating solid particles from a suspension, comprising a housing with a flotation chamber for receiving the suspension and at least one feed arrangement for supplying gas into the flotation chamber, wherein the at least one feed arrangement comprises at least one gas distributor element comprising at least one open-porous material is formed, wherein at least one surface region of the gas distribution element is arranged in the region of the flotation that this is wetted by the suspension, achieved in that the open-pore material is formed by a foam material of predominantly metal or plastic.

The temperature range in which flotation of a water-based suspension is usually carried out is between about 4 ° C and about 60 ° C. Compared to ceramics, metallic materials or plastics-based materials in this temperature band are less susceptible to brittle fracture. Due to the ductility of metallic materials and a - albeit for some plastics only to a small extent - present elasticity of plastics are better suited for use in flotation than brittle materials such as ceramics.

The use of an open-pore foam material additionally reduces the risk of breakage of the gas distributor element, since such materials have a high mechanical strength and only a low flow resistance with low weight. The three-dimensionally networked structure of a foam material behaves as a uniform whole, through which mechanical loads are distributed evenly over a large area. The open porosity of the foam material leads to a homogenization of the gas input into the suspension in terms of gas distribution, gas flow and gas bubble size, so that a particularly effective fumigation and thus a particularly effective discharge of superficially adhering to the bubbles, to be separated solids occurs.

Due to the ease of mechanical workability of a foam material, the shapes in which a gas distribution element can be inexpensively formed are almost unlimited. Thus, even complicated geometries can be realized, which could not be provided so far or only with high financial expenditure. This allows a gas distributor element which can be optimally adapted to the geometry of the respective flotation chamber and thus a uniformly high discharge of solid particles to be separated, viewed over the base surface of the flotation chamber.

The combination of ductile metal and foam material or plastic and foam material leads to a particularly stable, yet negligible in terms of size and weight gas distribution element, which is ideal for use in flotation devices to distribute gas evenly in the suspension.

Usable open-pore metal foams have a density which is usually about 10% of the starting material. The number of pores per inch (ppi) is usually in the range of 10 to 45 ppi in such metal foams. A foam material may be formed from a single metal, a metal alloy or a composite with a metallic matrix. Suitable metal alloys are based, for example, on aluminum. Suitable composites with a metallic matrix include, for example, hard material particles.

A plastic foam material is preferably formed from a flexible polyurethane foam. But it is also a variety of other plastics used, which give elastically deformable foams in the temperature range between 4 ° C and 60 ° C.

In order to form the smallest possible gas bubbles, the foam material preferably has pores with a mean pore diameter in the range of 0.5 mm to 4 mm. However, different foam materials with different average pore diameters can be used on a flotation device. Thus, it is possible to influence the local gas bubble size distribution in the flotation chamber in a targeted manner and to increase the yield.

It has proven useful if at least one gas distributor element of the flotation device at least partially delimits the flotation chamber on its underside. In this case, the gas distributor element can form the entire bottom of the flotation chamber or only partially form the bottom of the flotation chamber. Preferably, a plurality of gas distributor elements in the region of the bottom of the flotation chamber are arranged at a distance from one another in order to achieve the most uniform fumigation of the suspension.

Furthermore, it has proven useful if at least one gas distributor element is arranged in the flotation chamber, without being in direct contact with the housing. For example, gas distribution elements that are not in contact with the housing are arranged, arranged at a, gas outlet openings having supply line, wherein the foam material surrounds the region of the supply line comprising the gas outlet openings or at least the gas outlet openings covered. This supply device, comprising the supply line and / or the gas distributor element (s), is immersed in the region of the upper end of the housing, for example directly into the suspension. But also a mounting of the supply line to the housing or in an opening of the housing is possible.

It is advantageous if at least one baffle plate for gas flowing out of the at least one gas distributor element is arranged in the vertical direction above the at least one gas distributor element. This promotes the division of the outflowing gas bubbles into smaller gas bubbles and reduces the risk of clogging of the pores of the foam material by solid particles from the suspension.

In particular, it is advantageous if at least one gas distribution element is configured helically, wherein the helical gas distribution element is arranged concentrically to the vertical center axis of the flotation chamber. In this case, the helix of the helical gas distributor element preferably has a pitch angle in the range of 5 ° to 20 °, in order to realize optimum gassing.

In this case, the helical gas distributor element can be arranged without contact with the housing or the helical gas distributor element can be fastened to the housing in the region of a side facing the housing. In both cases, the helical gas distributor element is supplied with gas via a supply line. For example, helical gas distribution elements which are arranged without contact with the housing, equipped with a gas outlet openings having supply line, which is covered with the foam material. Helical gas distribution elements, which are arranged in contact with the housing are, for example, with a equipped rail-shaped supply line, wherein the foam material, the rail is covered.

It should be noted that, of course, different types of gas distribution elements can be used simultaneously on a flotation device. Thus, in addition to one or more gas distributor elements in the bottom region of the flotation chamber, at least one further gas distributor element can be arranged in the middle of the flotation chamber and / or at least one helical or otherwise shaped gas distributor element can be arranged in the region of the side walls of the vessel.

The foam material of a gas distribution element is in particular divided into individual segments, in order to allow a partial and in particular rapid and cost-effective replacement of only the affected segment in the case of maintenance.

Preferably, at least one nozzle arrangement for supplying suspension or of suspension and gas is present in the flotation chamber. Such nozzle arrangements are preferably arranged in the middle region of the flotation chamber, so that above the injection zone forms a kind of quiet zone on which the foam product floats and the suspension moves downwards in the flotation chamber and thus counter to the direction of movement of the gas bubbles rising in the suspension , This increases the probability of collision between solid particles and gas bubbles and thus the yield of the flotation process.

It has proven useful if the flotation chamber has a circular circumference when viewed in the vertical direction and the at least one nozzle arrangement is set up for supplying suspension or suspension and gas tangentially to the circular circumference into the flotation chamber. As a result, the suspension in the flotation chamber is placed in a helical flow, ie the suspension not only moves from top to bottom in the flotation chamber, but rotates at the same time around the vertical center axis of the flotation chamber.

The flotation device is preferably a pneumatic flotation cell or a columnar flotation cell, but in particular a hybrid flotation cell which combines both types. Details of these flotation devices have already been discussed in the introduction.

The use of a flotation device according to the invention for flotation of solid particles from a valuable material, in particular ore mineral, from a suspension having a solids content in the range of about 20 to 50% to form a foam product is ideal. It can realize a high yield of foam product and low downtime of the system.

FIG 1

eine erste Flotationsvorrichtung im Längsschnitt;

FIG 2

eine zweite Flotationsvorrichtung im Längsschnitt;

FIG 3

eine dritte Flotationsvorrichtung im Längsschnitt;

FIG 4

einen Querschnitt durch die dritte Flotationsvorrichtung in Höhe der Düsenanordnung.

The FIGS. 1 to 4 are intended to exemplify a flotation device according to the invention. So shows

FIG. 1

a first flotation in longitudinal section;

FIG. 2

a second flotation device in longitudinal section;

FIG. 3

a third flotation device in longitudinal section;

FIG. 4

a cross section through the third flotation at the height of the nozzle assembly.

FIG. 1 shows a first flotation device 1 for the separation of solid particles from a suspension S in longitudinal section. The flotation device 1 comprises a housing 2 with a flotation chamber 2a for receiving the suspension S and a feed arrangement 3 for supplying gas G, here in the form of air, into the flotation chamber 2a. The feed arrangement 3 comprises a plurality of gas distributor elements 4, which are each formed from at least one open-pored material. At least one surface area of each gas distribution element 4 is arranged in the region of the flotation chamber 2 a, that this is wetted by the suspension S. The open-pore material is formed here by a foam material made of metal, that is to say an open-pored metal foam. The gas distributor elements 4 are arranged in contact with the bottom of the vessel 2 and thus limit the flotation chamber 2 a partially on its underside.

The flotation device 1 furthermore has a nozzle arrangement 6 for feeding suspension S or optionally suspension S and gas G into the flotation chamber 2 a. The flotation chamber 2a has a circular circumference when viewed in the vertical direction, with the nozzle arrangement 6 being set up to supply the suspension S, or optionally suspension S and gas G, into the flotation chamber 2a tangentially to the circular circumference. The suspension S moves in the flotation chamber from top to bottom along a helical flow. On their way down the solid particles collide in the suspension S with the gas bubbles formed by the gas distribution elements 4 and rising to the surface of the suspension. In the process, hydrophobic solid particles to be deposited, in particular of ore mineral, adhere to the gas bubbles and are carried upwards with them. It forms on the surface of the suspension S, the foam product SP, which is withdrawn via a foam collection device, not shown here, such as a foam channel, and then further processed.

In the vertical direction above each gas distributor element 4, a baffle plate 5 is arranged in each case for gas G flowing out of the gas distributor elements 4. The gas bubbles rise from the respective gas distributor element 4 upwards and strike the respective baffle plate 5, whereby the gas bubbles are divided and thus increases the number of bubbles and the bubble size is reduced.

Residual residual pulp R, to which the hydrophobic solids particles to be removed have been removed, is removed from the flotation chamber 2a via a drain 8.

FIG. 2 shows a second flotation device 1 'in column form for the separation of solid particles from a suspension S in longitudinal section. Same reference numerals as in FIG. 1 identify similar elements. There are two feed arrangements 3, 3 'for supplying gas G to the flotation chamber 2a.

A first of the two feed arrangements 3 comprises a supply line 3a, which has here not visible gas outlet openings and in the region of the gas passage openings with the foam material of the gas distribution element 4a, here of open-cell polyurethane flexible foam, is sheathed. The supply line 3a is submerged from above into the suspension S, the gas distributor element 4a being located centrally in the flotation chamber 2a. Of course, several such feeders 3 can be used in parallel and arbitrarily distributed here. In this case, a supply line 3a can supply a plurality of gas distributor elements 4a with gas, or a separate supply line 3a can be provided per gas distributor element 4a.

The second of the two feed devices 3 'comprises a gas distributor element 4b of open-pored metal foam, which completely delimits the flotation chamber 2a on its underside.

The second flotation device 1 'likewise has a nozzle arrangement 6 for feeding suspension S or optionally suspension S and gas G into the flotation chamber 2 a. The flotation chamber 2a has a circular circumference when viewed in the vertical direction, with the nozzle arrangement 6 being set up to supply the suspension S, or optionally suspension S and gas G into the flotation chamber 2a, tangentially to the circular circumference.

FIG. 3 shows a third flotation device 1 '' in column form for the separation of solid particles from a suspension S in longitudinal section. Same reference numerals as in the FIG. 1 and 2 identify similar elements. It is here, as already in FIG. 2 , two feed arrangements 3, 3 'for supplying gas G to the flotation chamber 2a.

A first of the two feed arrangements 3 comprises a supply line 3a, which widens in a funnel shape and is closed at its end with foam material of a gas distributor element 4a. The foam material is subdivided into segments that enable segmental replacement in the event of maintenance. In this case, the individual segments may be formed of different foam materials, i. differ in material and / or average pore diameter. The supply line 3a is guided laterally through the housing 2 into the suspension S, wherein the gas distributor element 4a is located centrally in the flotation chamber 2a. Of course, several smaller such Zuführanordnungen can be used in parallel and arbitrarily distributed here. In this case, a supply line 3a can supply a plurality of gas distributor elements 4a with gas, or a separate supply line 3a can be provided per gas distributor element 4a.

The second of the two feed devices 3 'comprises a helical gas distributor element 4c of open-pored metal foam, which runs along the housing 2 and whose helical longitudinal axis is arranged concentrically to a central axis M of the flotation chamber 2a. The metal foam is arranged here on a rail-shaped supply line, via which the gas is supplied to the metal foam. Instead of the helical gas distributor element 4c, a plurality of horizontally or obliquely arranged, annular gas distributor elements may also be present here.

The third flotation device 1 "likewise has a nozzle arrangement 6 for feeding suspension S or optionally suspension S and gas G into the flotation chamber 2 a. The flotation chamber 2a has a circular circumference when viewed in the vertical direction, with the nozzle arrangement 6 being set up to supply the suspension S, or optionally suspension S and gas G into the flotation chamber 2a, tangentially to the circular circumference.

Here also schematically a foam channel 7 for discharging the formed foam product SP 'is shown.

FIG. 4 schematically shows a cross section through the third flotation device 1 '' at the level of the nozzle assembly 6. It can be seen that the suspension S is injected tangentially and thus in a rotational movement about the central axis M of the flotation chamber 2a is added. In this case, alternatively and depending on the diameter of the flotation chamber 2a, two or more nozzle arrangements 6 may be provided which are arranged in an analogous manner.

The FIGS. 1 to 4 merely show examples of a flotation device according to the invention. Thus, according to the invention, a multiplicity of further vessel shapes, vessel heights, arrangements of gas distributor elements, combinations of different foam materials, etc. are possible, which are not shown in detail here.

Claims (12)

Flotation device (1, 1 ', 1'') for separating solid particles from a suspension (S), comprising a housing (2) with a flotation chamber (2a) for receiving the suspension (S) and at least one feed arrangement (3, 3'). ) for supplying gas (G) into the flotation chamber (2a), wherein the at least one feed arrangement (3, 3 ') comprises at least one gas distributor element (4, 4a, 4b, 4c) which is formed from at least one open-pored material, wherein at least one surface region of the gas distributor element (4, 4a, 4b, 4c) is arranged in the region of the flotation chamber (2a) such that it can be wetted by the suspension (S), characterized in that the open-pore material is predominantly metal or a foam material Plastic is formed. Flotation device according to claim 1, characterized in that at least one gas distributor element (4, 4b) at least partially delimits the flotation chamber (2a) on its underside. Flotation device according to claim 1 or 2, characterized in that at least one gas distributor element (4a) is arranged in the flotation chamber, without being in direct contact with the housing. Flotation device according to one of claims 1 to 3, characterized in that at least one gas distributor element (4c) helically configured, wherein the helical gas distributor element (4c) is arranged concentrically to the vertical center axis (M) of the flotation chamber (2a). Flotation device according to claim 4, wherein the helical gas distributor element (4c) is fastened to the housing (2) in the region of a side facing the housing (2). Flotation device according to one of claims 1 to 5, characterized in that in the vertical direction above the at least one gas distributor element (4, 4a, 4b, 4c) at least one baffle plate (5) for from the at least one gas distributor element (4, 4a, 4b, 4c ) outflowing gas (G) is arranged. Flotation device according to one of claims 1 to 6, characterized in that at least one nozzle arrangement (6) for supplying suspension (S) or suspension (S) and gas (G) in the flotation chamber (2a) is present. Flotation device according to claim 7, characterized in that the flotation chamber (2a) seen in the vertical direction has a circular circumference and that the at least one nozzle assembly (6) to the circular circumference tangential supply of suspension (S) or suspension (S) and Gas (G) is arranged in the flotation chamber (2a). Flotation device according to one of claims 1 to 8, characterized in that the foam material has pores with an average pore diameter in the range of 0.5 mm to 4 mm. Flotation device according to one of claims 1 to 9, characterized in that the foam material is formed of a single metal, a metal alloy or a composite with a metallic matrix. Flotation device according to one of claims 1 to 9, characterized in that the foam material is formed of a flexible polyurethane foam. Use of a flotation device (1, 1 ', 1'') according to one of claims 1 to 11 for the flotation of solid particles from a valuable material, in particular ore mineral, from a Suspension (S) having a solids content in the range of 20 to 50% to form a foam product (SP).

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