The present invention relates to a device and to a method for mixing, in particular dispersing, in accordance with the preamble of the independent claims.
In practice, for example, in the paint industry, a predefined amount of liquid is frequently pre-mixed with a predefined amount of a powdery solid, as a rule pigment. Mixtures of this type are subsequently ground further, where necessary, in agitator mills and dispersed. The production of paints and lacquers or similar is an example of industrial applications.
The term mixing in the present case is understood as meaning combining materials or material flows in such a manner that as uniform a composition as possible is achieved; within the scope of the invention, the mixing serves in particular for producing dispersions, that is to say for dispersing. The term dispersion is understood here as meaning a heterogeneous mixture produced from at least two materials which do not dissolve or scarcely dissolve into one another or bond chemically with one another. During the dispersing operation, a material (disperse phase) is distributed as finely as possible into another material (dispersing agent or continuous phase), optionally by using grinding aids; ball-shaped grinding aids are frequently used, for example, in agitator mills. The present invention relates above all to (the production of) suspensions, that is to say dispersions where a liquid forms the continuous phase and a solid forms the disperse phase. In addition to the uniform distribution of the disperse phase in the continuous phase, the term dispersing is also understood as meaning the wetting of the material to be dispersed (and optionally the subsequent stabilization). Crushing can typically be the dissolving of agglomerates into primary particles. Aggregates or associates (if condensing is brought about by van-der-Waals forces or stronger chemical types of formation) can also be crushed into primary particles, however, during the dispersing. Whereas the dissolving of agglomerates can also occur in devices without grinding aids, as in a disperser or dissolver, devices with grinding aids, such as, for example, an agitator mill with ball-shaped grinding aids, are required to crush aggregates or crystals. Aggregates in the broader sense can also be understood here as meaning larger crystalline or amorphous structures. Where aggregates, crystalline or amorphous structures are crushed, true crushing is referred to.
Device of the type in question for mixing two materials, in particular a liquid and a solid, such as, for example, a powder, normally have a housing and a rotor which rotates therein. The materials are introduced into the housing by means of at least one feed line. During an operation of the device, the materials are mixed by means of the rotor and are then conducted out of the housing.
A device for dispersing, and an associated method are described in U.S. Pat. No. 6,029,853. The device for dispersing comprises a chamber for dispersing, at least one agitating disk, an inlet through which the liquid with the material to be treated and the dispersion medium are sucked in as a result of rotation of the agitating disk, an outlet and a separating device. The separating device is arranged at the outlet. The grinding aids are separated from the dispersion by means of the separating device. In addition, the separating device can leave the dispersion through the outlet, with the grinding aids being retained, as described.
DE 10 2010 053 484 discloses an agitator bead mill with a separating device for grinding aids, wherein the separating device is arranged about an axis of rotation. The separating device consists of two components, wherein one component is at least one separating device and a second component is a dynamic element for generating a material flow. The device comprises a very small dynamic gap as a separating device, and therefore the output is reduced.
DE 1 507 493 discloses an agitator bead mill with disk-shaped agitating tools in a cylindrical housing, wherein one or two disks are fitted above the rotor and, with stator elements, produce dynamic gaps. The output is also greatly limited here by the small number of outlet gaps. Furthermore, the possibility of discharging the mixture from the device is possible only very locally.
DE 35 21 668 discloses an agitator mill in which the separating device for separating off the grinding bodies consists of a sieve. Such a sieve can easily become blocked and therefore increases the maintenance frequency of the device.
It is therefore the object of the present invention to avoid the disadvantages of the prior art and in particular to create a device and a method for mixing, dispersing and in particular for separating off grinding aids, the device enabling a high throughput of material and at the same time reducing the probability of a blockage or clogging up of a flow.
The object is achieved by a device and a method for mixing as claimed in the characterizing part of the independent claims.
In particular, the object is achieved by a device for mixing, in particular dispersing, which comprises the following features:
The openings of the first gap-forming element and the openings of the second gap-forming element are arranged in such a manner that a mixture produced from the supplied materials is conductible from the first process region into the second process region through the openings in the two gap-forming elements.
A device of this type results in a high throughput without there being any risk of a blockage.
The gap-forming elements have to be rotatable relative to each other, and therefore both elements can also be designed in a rotatable manner. In this case, the rotational speeds and/or the direction of rotation have to differ.
The openings in the gap-forming elements are preferably arranged in such a manner that the openings do not overlap and material can only pass from the openings of the first gap-forming element to the openings of the second gap-forming element through a gap between the openings. Once the gap has been passed, the openings are intended to enable a large material flow and therefore have an opening diameter/opening cross section which is large compared to the gap.
The gap according to the invention is formed between the two gap-forming elements. The smallest extent of the openings in the first gap-forming element is preferably at least three times as large as the largest extent of the gap between the two gap-forming elements. In addition, the smallest extent of the openings in the second gap-forming element is preferably also at least three times as large as the largest extent of the gap between the two gap-forming elements. For an embodiment in which the second gap-forming element comprises annular gaps, the extents of the annular gaps obviously have to substantially correspond to the extent of the gap between the gap-forming elements or have to be smaller than the gap between the gap-forming elements. In an embodiment with annular gaps of a gap-forming element, a high throughput is achieved by means of a high number of annular gaps. The gap according to the invention between the first gap-forming element and the second gap-forming element has a separating function. The extent of the gap prevents particles which are larger than the gap from passing into the second process region.
At least one, preferably two, preferably dynamic, gaps can be formed between the housing and the first gap-forming element.
Consequently, elements which are too large are also prevented from passing between the housing and the first gap-forming element. Nevertheless, further separating devices are not necessary.
The first gap-forming element can surround the second gap-forming element and a gap of a maximum of 3 mm, preferably 1.0 mm and particularly preferably 0.5 mm, can be formed between the two elements. The minimum gap has a transverse extent of 0.1 mm.
In particular, a gap, the maximum extent of which is smaller than the smallest element of the grinding bodies which are pourable or poured into the device, is formed between the two gap-forming elements. The gap is preferably a maximum of half the size of the diameter of the smallest grinding body.
Grinding tools which are designed for mixing or dispersing the materials introduced in the first process region can be arranged on the first gap-forming element and/or on the housing.
Grinding tools of this type can be pins or disks or other known embodiments of grinding tools.
The effectiveness of the dispersing is increased by means of grinding tools. The first gap-forming element is preferably designed as a rotor, and therefore the movement of the supplied materials and possibly of the grinding bodies is generated by means of the grinding tools on the rotor and dispersion is thus achieved in the first process region. The first gap-forming element can extend substantially completely along a length of the first process region.
Consequently, a large surface is provided with gaps which cannot clog up and still achieve a large flow rate.
Grinding bodies, the forwarding of which into the second process region is preventable by means of gaps, in particular dynamic gaps, can be pourable into the first process region.
The dynamic gaps can be formed between the first gap-forming element and the second gap-forming element and additionally between the first gap-forming element and the housing. Therefore, only material which has been completely dispersed passes into the second process region, and the movement at the gap edges means that the gaps cannot be blocked.
Preferably, no static separating device is formed between the first and the second process region.
Consequently, the static separating device cannot be blocked. A static separating device is a separating device where the edges of the openings through which the mixture passes do not move. Static separating devices are therefore in particular fixedly mounted sieves.
Alternatively, the second gap-forming element can be designed as a static separating device, wherein the openings in the static separating device are preferably smaller than the minimum diameter of the grinding bodies. Particularly preferably, the openings in the static separating device are formed by annular gaps.
A static separating device of this type reliably holds back grinding bodies and oversized particles from the second process region.
Both gap-forming elements can be formed in a cylindrical or conical manner.
Consequently, a large surface can be obtained for the passage from the first into the second process region along with a high level of rotational energy at the same time.
Alternatively, it would be conceivable to design the gap-forming elements as circular disks which are arranged between the first and the second process region.
The gap between the first gap-forming element and the second gap-forming element can have a longitudinal extent which is formed parallel to the axis of rotation. Where there are circular-disk-shaped gap-forming elements, the gap can be formed substantially perpendicular to the axis of rotation. Where the gap-forming elements are conical, the gap can be at an angle of between 1° and 89° with respect to the axis of rotation.
Consequently, reliable separation of the grinding aids can be achieved without blockages being possible.
The openings of the gap-forming elements can extend along a length of at least 50%, preferably 60%, particularly preferably 70%, of the length of the first gap-forming element in the first process region.
Consequently, a high throughput can be achieved.
The relative details refer here not to the extent of the openings, but rather to the region which is provided with openings. Furthermore, two or more bores can be connected to one another at the periphery of the second gap-forming element by a groove, preferably a milled groove. The groove obviously must not overlap with the openings in the first gap-forming element. A large outflow volume can therefore be created and the mixture is rapidly discharged into the second process region.
The housing of the device can furthermore comprise a pump housing or can be connected to a pump housing which forms a pump on the housing of the device. The pump housing and the housing of the device can be formed in one piece or in multiple pieces. In the case of a multiple-piece design, the pump housing is preferably flange-mounted on the housing of the device.
A pump is arranged in the pump housing.
The required pump is therefore directly connected to the device for mixing, and only a control means and a few external lines are necessary.
The same shaft as for driving the moving gap-forming element and/or the grinding tools can be used to drive the pump.
This results in fewer individual parts and, as a result, in less complexity.
The pump housing comprises a pump inlet and a pump outlet.
The pump can be a centrifugal pump, a liquid ring pump, a side-channel pump or a positive-displacement pump, such as, for example, an impeller pump.
The object is furthermore achieved by a method for dispersing materials in a device, preferably as described above. The method comprises the steps:
With a method of this type, relatively large amounts of materials can be mixed, in particular dispersed, particularly preferably pre-dispersed, without materials blocking the separating devices and maintenance of the device being necessary.
The mixture can furthermore be additionally conducted through one or more dynamic gaps between the first gap-forming element and a housing of the device.
Consequently, a dynamic separating device which does not become blocked and at the same simplifies the design of the device is also provided between the housing and the device.
The dispersing in the first process region can be achieved by grinding bodies and/or grinding tools.
Grinding tools can be disks or pins or similar grinding tools which are already known from the prior art. Grinding bodies are hard, round or elliptical bodies which contribute to the dispersing of the material. The grinding bodies are adapted to the desired degree of dispersion and can also have a different size depending on the material which is introduced. The grinding bodies are held back by the gap/the gaps between the gap-forming elements and/or the housing.
The dispersing can be achieved by grinding bodies which have a diameter which is at least 1.5 times, preferably 3 times, in particular 10 times, larger than the largest gap as the transverse extent.
Consequently, the grinding bodies cannot pass through the gap and the gap serves as a dynamic separating device.
The mixture can be conducted through at least 4, preferably 20, particularly preferably 100, openings in the first gap-forming element.
The mixture can furthermore be conducted through at least 4, preferably at least 50, particularly preferably a minimum of 200, openings in the second gap-forming element.
Consequently, an optimized throughput of mixture can be achieved by means of the number of openings. The openings in the second gap-forming element can be formed at least in part by bores.
Furthermore, two or more bores can be connected to each other on the periphery by a groove, preferably a milled groove. The groove obviously must not overlap with the openings in the first gap-forming element. A large outflow volume can therefore be created and the mixture is rapidly discharged into the second process region.
The invention is explained in more detail below with reference to figures, in which:
The embodiment of the device 1 in
Apart from the pump housing 21, the design of the device substantially corresponds to the embodiment in
Number | Date | Country | Kind |
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15164059 | Apr 2015 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/056216 | 3/22/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2016/165917 | 10/20/2016 | WO | A |
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International Search Report Corresponding to PCT/EP2016/056216 dated Jul. 5, 2016. |
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Number | Date | Country | |
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20180099254 A1 | Apr 2018 | US |