WO1993012871A1

WO1993012871A1 - Process for dispersing, mixing or homogenising mixtures and device for implementing it

Info

Publication number: WO1993012871A1
Application number: PCT/AT1992/000172
Authority: WO
Inventors: Wolf-Dieter Kreuziger
Original assignee: Kreuziger Wolf Dieter
Priority date: 1991-12-20
Filing date: 1992-12-21
Publication date: 1993-07-08
Also published as: KR930703064A; EP0572610A1; CA2104388A1; EP0572610B1; ES2094520T3; JPH06505437A; DK0572610T3; DE59207190D1; ATE142902T1

Abstract

In a process for dispersing, mixing or homogenising solid/liquid and/or liquid/liquid mixtures, the dispersion or emulsion to be homogenised is introduced into a rotating grinding chamber (5) at least partly filled with grinding bodies and bounded by at least two rotary wall components (2, 4). The dispersion or emulsion to the homogenised is taken through the grinding chamber (5) transversely to the axis of rotation (3) of the wall components (2, 4). In a device for implementing the process with a grinding chamber (5) in which there are grinding bodies, the grinding chamber (5) is bounded by at least two wall components (2, 4) which can be rotated and it has at least one inlet and/or outlet aperture (15, 16) on its sides facing and away from the axis of rotation (3).

Description

7.u DJsnsrσierftn procedure. Mixing or homogenizing of mixture and device for carrying out this method

The invention relates to a method for dispersing. Mixing or homogenizing solid / liquid and / or liquid / liquid mixtures and on a device for carrying out this method with a grinding chamber in which grinding media are arranged.

According to an older proposal according to the Austrian application A 2384/90 (AT-PS), a device for mixing, homogenizing or converting at least two components was already known, in which separate mixing tools could be dispensed with. In contrast to known agitators, which are immersed in a container, the aim of this older proposal was to set the material to be mixed itself in motion relative to one another, so that a strong relative movement of the material to be mixed occurred at adjacent areas to each other is formed. The mixing zone formed in this way should lead to a largely homogeneous mixing in the area of the mixing zone. In order to vary the mixing result, it has also been proposed to pressurize the mixing zone by changing the volume of the rotating container, the use of such a compression pressure, in particular with regard to the possibility of achieving desired chemical reactions of individual components with one another Meaning was. Continuous operation was possible with the older proposal in that the mixed material could be drawn off in the axial direction of the container, ie in the direction of the axis of rotation, the partial area in which the most intensive mixing took place onto the opposite end faces of opposed, open, cylindrical containers was limited. The invention now aims to improve a device of the type mentioned at the outset such that the mixing zone can be substantially enlarged in the case of small structural dimensions, and furthermore the possibility is created of homogenizing even when heavily used to improve mutually miscible substances, in particular in the case of solid / liquid mixtures and liquid / liquid mixtures, in order to obtain a dispersion or an emulsion. At the same time, the method according to the invention is intended to provide the possibility of effectively counteracting any lump formation that may occur in the production of such dispersions and of reliably separating the smallest size of agglomerations. In addition to reliable mixing, the process according to the invention is also intended to achieve wet grinding and intensive dispersion when liquids of relatively high viscosity are used and in conventional wet grinding processes the high viscosity makes it difficult to separate the grinding media from the liquid components. According to the invention, despite the high viscosity, a reliable and simple separation of grinding media should succeed at the same time, even when grinding media with an extremely small diameter and extremely low density differences are used for the dispersion to be produced. The use of starting materials with a higher viscosity should also make it possible to process concentrates, as a result of which the throughput, for example in the production of dilutable dyes based on synthetic resin pigments, can be substantially reduced.

To achieve this object, the process according to the invention essentially consists in introducing the dispersion or emulsion to be homogenized into a rotating grinding chamber which is at least partially filled with grinding media and delimited by at least two rotatable wall elements, and in that the dispersion to be homogenized or emulsion transverse to the axis (s) of rotation of the wall elements through the Annulus is moved or passed through. Because the dispersion or emulsion to be homogenized is introduced into a rotating grinding chamber which is at least partially filled with grinding media and delimited by at least two rotatable wall elements, a mixing zone is formed between the rotating wall elements, which overall has a relatively large partial area with small dimensions an intensive mixing guaranteed. At the same time, the at least partial filling of the grinding chamber with grinding media ensures intensive wet grinding, with an intensive acceleration of the grinding media and mixing taking place at the interface between the rotating areas of the grinding chamber. Due to the rotation of the rotatable wall elements and thus the rotation of the grinding chamber, a centrifugal force is simultaneously exerted on the grinding media, which leads to the grinding media moving against one another over a larger diameter of the grinding chamber with great pressure and therefore having a high pressure in this partial area of the grinding chamber Compression pressure and thus an improved wet grinding result is achieved. Simultaneously with this directed movement of the grinding media in the direction of the centrifugal force, the separation of the grinding media from the emulsion or dispersion produced is also improved, so that, for example, on the side of the grinding chamber opposite the compression of the grinding media to a smaller diameter the finished mix can be drawn off in a simple manner without the need for conventional separation techniques, such as the use of filters or sieves, which tend to become blocked. The separation of the grinding media from the dispersion or the emulsion can thus be substantially improved by the process according to the invention, this improvement being, among other things, that the use of screens or filters when removing the mixture can be dispensed with, for which purpose process according to the invention is carried out in such a way that the dispersion or emulsion to be homogenized transversely to the (the) Rotation axis (s) of the wall elements is moved or passed through the grinding chamber.

In the case of wall elements rotating relative to one another, the partial area of intensive mixing between the rotating partial areas of the grinding chamber or mixing chamber is formed by an annular surface which is essentially normal to the axes of rotation. With a corresponding design of the rotating wall elements, the division plane and thus the zone of the most intensive mixing can also lie in a surface which corresponds to the lateral surface of a cone. The mixing or swirling depends on the relative speed that exists between adjacent areas of the mixing space or grinding space. If the wall surfaces rotate in opposite directions, this relative speed and thus the dispersing action become particularly high, although overall attention should also be paid to a resulting centrifugal force in the grinding chamber in order to separate the grinding media. The method can therefore advantageously be carried out in such a way that the mixing operation is carried out between wall elements rotating relative to one another at different speeds and / or directions of rotation.

The axes of rotation of the wall elements which can be rotated relative to one another can be different from one another and can run essentially parallel to one another, as a result of which a certain eccentricity of the rotational movement in relation to the interface between the particles rotating relative to one another and thus particularly intensive mixing can be achieved.

If the axes of rotation are inclined to one another, a flexing effect can also be achieved to improve the mixing over the entire radial extent of the grinding chamber. When using wall elements with mutually inclined axes of rotation, the wall elements can operate at the same speed and in the same direction of rotation are driven, which results in the fact that despite a slight relative movement between the disks or wall elements and the regrind, a total movement of the regrind-grinding mixture is produced with each revolution. This means that the energy input can take place optimally and there is no risk of local overheating, especially when processing highly viscous masses. The possibility of being able to drive both wall elements at the same speed and still achieve an optimal grinding / mixing effect also means a significant simplification of the overall structure and ultimately improves the centrifugal effect on all grinding media.

The method is preferably carried out in such a way that the mixture or grinding media / grinding media mixture is set in rotation at the same rotational speed as the two wall elements, and that the mixing material or the grinding media / grinding media mixture is at least once in each direction in the direction of rotation Axis of rotation and once in the direction away from the axis of rotation. Overall, this results in the fact that the relative movement between the grinding media / material to be ground and the driving disks or wall elements in the direction of the rotational movement is practically zero, and the exclusive mixing and grinding action is effective due to the displacement of the mixture in the radial direction. It is thus possible to set the contact pressure and separating effect solely as a function of the common speed of these disks.

To simplify the seal and to simplify the construction of a corresponding device, the axes of rotation can, however, also be arranged coaxially with one another without further ado. In addition, there is the possibility, even outside of the grinding chamber delimited by the rotatable wall elements, of creating an additional possibility of premixing under high shear stress. For this purpose, the process according to the invention is advantageously carried out in such a way that the dispersion or emulsion to be homogenized is subjected to a shear stress before it enters the grinding chamber between rotating surfaces on the outside of the wall elements of the grinding chamber is subjected to, such a procedure using a structurally relatively simple device results in additional intensive mixing.

A good separation of the grinding media from the dispersed or homogenized mixture without complex separation technology can be achieved in that the dispersion or emulsion to be homogenized is conveyed through the grinding chamber counter to the direction of movement of the grinding media caused by the centrifugal force.

The material to be homogenized or dispersed can advantageously be fed in from the outside inwards in the radial direction, the method being able to be carried out continuously in a particularly simple manner in such a way that the homogenized mixture is drawn off via an axial channel. In order to set the appropriate pressure conditions and flow conditions, the outflow via the axial channel can be throttled accordingly. Overall, the possibility arises of freely selecting the rotational speeds and / or the direction of rotation of the wall elements rotating relative to one another over a wide range, and the possibility of adjusting the respective flow rate and pressure conditions, making them adaptable to different starting materials, and it succeeds homogenizing and mixing even difficult-to-mix, highly viscous substances with simultaneous improvement of the homogenization and the fine distribution or dispersion. In this case, the procedure is preferably such that the grinding chamber is filled to a maximum of 75% by volume, preferably 60% by volume, with grinding media with an effective diameter of less than 0.5 mm, preferably less than 0.1 mm becomes.

The device according to the invention for carrying out this method, which, in particular, takes up little space and requires little construction and engineering Adaptability to a wide variety of starting materials with improved homogenization and mixing at the same time is advantageously designed in such a way that the grinding chamber is delimited by at least two wall elements which can be driven in rotation and that the grinding chamber is on its axis (s) of rotation. facing and facing sides at least has a feed and / or a discharge opening. The feed opening can be connected to the radially outer end wall of the grinding chamber, the discharge opening being able to open into an axial channel in a region close to the axis. Both of these openings can be formed in a particularly simple manner by slots extending over the circumference of the grinding chamber, the design advantageously being such that the slots are in a common division plane of the normal to the axis of rotation of the wall elements Grinding room. With such a design, there is a relatively large zone of intensive mixing with, at the same time, small dimensions in the area of the ring area defined between the rotating partial areas. Instead of forming a slot in the region near the axis as a discharge opening by means of corresponding axial extensions of the wall elements, the discharge opening can of course be formed directly by an axial channel formed in at least one wall element, it being possible for corresponding throttling means to be provided in this channel . The grinding chamber generally has a circular outer circumferential surface and, in the case of a slot-shaped opening in the region near the axis, is designed as a torus or annular space.

A further improvement in the adjustability of the pressure conditions and the intensity of the wet grinding can of course be achieved if the grinding media are subjected to a particularly close proximity to one another while moving in the direction of the centrifugal force, while at the same time increasing the pressure forces which act towards one another become. This is advantageously achieved through a tive embodiment, in which the grinding chamber delimited by the wall elements of the grinding chamber is tapered in cross-section in a cross-sectional plane containing at least one axis of rotation transverse to this axis of rotation. When the grinding media are moved into such a tapering cone in accordance with the centrifugal force, intensive mixing is ensured over the entire cross-section of the grinding chamber, even outside the area in which the mixing takes place primarily, as a result of which the homogenization effect and the division smallest agglomerate works even better.

The design is advantageously made such that the wall elements are formed by half-shells which are rotatably mounted about a common axis and are connected to separate drives, which results in a simple structure with simple storage. Advantageously, premixing is possible on the outside of the mixing chamber or grinding chamber by using high shear forces in that the design is such that a wall element is connected in a rotationally fixed manner to a part spanning the second wall element while forming a gap, and in that the supply line opens into this gap.

Intensive mixing, in which a shear stress can optionally be dispensed with, can be achieved with a design of the device in which the axes of rotation of the wall elements are arranged inclined relative to one another and adjoin one another including an obtuse angle. If such a device is operated with the same speed and the same direction of rotation of the wall elements, in particular disks, the relative movement of the wall elements is reduced to a cyclical crushing, which creates a flexing effect, which naturally can also be superimposed on shear stress at interfaces. if differences in speed or direction of rotation are permitted. For further adjustability and adaptability of the conditions to different mixtures, the design is preferably such that the angle between the axes of rotation of the wall elements is infinitely adjustable.

The invention is explained in more detail below with the aid of an exemplary embodiment shown schematically in the drawing. 1 shows a partial section through a first embodiment of a device according to the invention for carrying out the method according to the invention; and FIG. 2 shows a modified embodiment of a device according to the invention with wall elements with axes of rotation inclined to one another.

In Fig.l only half of the rotationally symmetrical design of the device is shown in section, the overall device resulting from reflection on the common axis of the two wall elements delimiting the grinding chamber.

The device for dispersing, mixing or homogenizing solid / liquid or liquid / liquid mixtures consists of a housing, generally designated 1, in which a first wall element 2 in the form of a half-shell can be rotated about an axis of rotation 3 by a not shown provided drive is stored. The shell-shaped wall element 2 defines, with a second, also rotatably mounted, shell-shaped wall element 4, a grinding chamber 5 designed as an annular space, the grinding chamber being indicated by dashed lines in the second half of the drawing by 5 'to illustrate the symmetrical design. In the embodiment shown, the second wall element 4 is also driven to rotate about the axis 3 by a drive, not shown. Storage for the wall element 4 in the housing 1 is indicated by 6. With the first rotating wall element 2 is the outside of the second wall element

- 10 -

4 overlapping part 7 non-rotatably connected, as indicated by 8, the bearings for the first wall element 2 or the part 7 connected thereto are indicated by 9 and 10.

The two shell-shaped wall elements 2 and 4 delimiting the grinding chamber 5 rotate about the common axis 3 at different speeds and / or different directions of rotation. Via a feed line or a connection 11, the material to be mixed or the solid / liquid and / or liquid / liquid mixtures enters the gap 12 between the outer wall 13 of the second wall element 4 and the inner wall 14 of the part connected to the first wall element 2 7, wherein in this gap 12 a strong shear stress of the introduced material is caused by the elements 4 and 7 rotating at different speeds and / or different directions of rotation. The material then passes through a slot or a feed opening 15 into the grinding chamber or annular space 5, in which up to 75% by volume of grinding media, not shown, with an effective diameter of less than 0.5 mm are arranged, around which To disperse, mix or homogenize the supplied materials. In the grinding chamber 5, too, the supplied material is exposed to shear and mixing stresses in that the two wall elements 2 and 4 delimiting or defining the grinding chamber are driven at different speeds and / or different directions of rotation, resulting in a mixing surface which in the is essentially formed by a circular area. The correspondingly mixed or homogenized material is drawn off via a gap 16 facing the axis of rotation 3 between the rotating wall elements and applied via an axial channel 17. The gaps 15 and 16, which define the feed and discharge opening for the material to be mixed or homogenized, lie in a common plane normal to the axis of rotation 3. The grinding chamber 5 has a cross-section which tapers conically from the region of the discharge opening 16 close to the axis to the region of the supply opening 15 remote from the axis, so that, supported by the direction of movement caused by the centrifugal force, the grinding bodies in the grinding chamber or annular space 5 have a high area in the area of the inlet Grinding body density is present in the grinding chamber 5. At the same time, the arrangement of the inlet and outlet openings in the area of the outlet opening 16 means that filters or sieves or the like can be arranged. to separate the grinding media, since the grinding media are effectively moved away from the axis 3 by the centrifugal force, so that even in the event that the passage cross section of the gap or the discharge opening 16 is larger than the particle size of the Even with high viscosity of the materials to be mixed, grinding media prevent the grinding media from escaping due to the high rotational speeds and the stresses. Throttling devices (not shown in more detail) are provided in the axial channel 17 for regulating or controlling the flow in order to achieve a desired result.

In the event that the two wall elements 2 and 4 have mutually different, mutually parallel axes of rotation, there is an eccentric movement of one wall element relative to the other, so that in particular a corresponding narrowing and widening of the gap 12 between the outer surface of the wall element 4 and the inner surface of the rotating part 7 can be achieved.

In the event that the mixtures to be homogenized or dispersed have a greater specific weight than the grinding media, the function of the inlet and outlet openings 15 and 16 can be inverted if the parameters are appropriately selected during mixing or homogenization .

In the embodiment according to FIG. 2, a shell-shaped wall element 2 is in turn about an axis of rotation 3 by a Drive (not shown in more detail) is driven to a rotary movement. With the wall element 2, in turn, a part 7 overlapping the second wall element 4 is connected in a rotationally fixed manner, only the bearings 10 being indicated. In a departure from the embodiment according to FIG. 1, the second shell-shaped wall element has a rotation axis 18 which is different from the axis of rotation 3 of the first wall element 2 and which forms an obtuse angle with the axis of rotation 3. The inclined arrangement of the second wall element 4 relative to the first rotatable wall element 2 results in a grinding chamber 5, the cross-section of which, in turn, tapers from the central region to the regions remote from the axis, the inclined position of the wall element 4 relative to the wall element 2 in different sections along the circumference results in a different cross-sectional area. This makes it possible, when the shell-shaped wall elements 2 and 4 are driven in the same direction and at the same speed, to move the entire material to be homogenized at the same time, including the schematically indicated grinding balls 19, without any significant relative movement between the grinding bodies 19 and the Discs 2 and 4 occurs. The mixing and homogenization takes place in this embodiment by means of a corresponding flexing effect, which is caused by the different cross-sectional areas, especially at the radially outer regions of the grinding chamber 5, by the inclined position of the wall element 4 relative to the wall element 2. A similar flexing effect to the grinding chamber 5 results in the gap 12 between the outer surface 13 of the wall element 4 and the inner surface 14 of the part 7 which overlaps the wall element 4 and which is connected in a rotationally fixed manner to the first wall element. Corresponding preprocessing thus also results in this embodiment before the material enters the grinding chamber 5 via a slot or gap 15, similarly to the embodiment according to FIG. 1, the mixed material directly in the embodiment according to FIG the axial channel 17 is withdrawn. The Mahlkörperchen be fugalkraft by Zentri¬ turn in the rota ^' tion axes 3 or. 18 distant areas of the grinding chamber 5 moves, the cross-sectional area tapering to different extents again in turn immediately upon entry of the material to be mixed or. to homogenize material in the grinding chamber 5, there is a particularly heavy load by the grinding media 19.

In this embodiment, using a fulling effect, it follows that the mixing and grinding action is practically exclusively effected by the displacement of the mixture in the radial direction. Overall, it follows that there is no relative movement between the wall elements 2 or 4 and the material to be mixed and that the mixture is moved at least once in the direction of the axes of rotation 3 and 18 and away from them with each revolution of the wall elements.

For adaptability to different material to be mixed or homogenized, the angle between the axes of rotation 3 and 18 can be infinitely adjustable up to a maximum value, starting from a position of the axes 3 and 18 in alignment with one another.

Claims

Claims:

1. A method for dispersing, mixing or homogenizing solid / liquid and / or liquid / liquid mixtures, characterized in that the dispersion or emulsion to be homogenized in a rotating, at least partially filled with grinding media (19) and at least two rotatable Wall elements (2,4) limited grinding chamber (5) is introduced, and that the dispersion or emulsion to be homogenized transversely to the axis (s) of rotation (3,18) of the wall elements (2,4) through the grinding chamber (5th ) is moved or passed through.

2. The method according to claim 1, characterized in that the mixed material or grinding media-grinding material mixture is rotated at the same rotation speed as the two wall elements (2, 4), and in that the mixing material or the grinding media / grinding material mixture every revolution is moved at least once in the direction of the axis of rotation (3, 18) and once in the direction away from the axis of rotation.

3. The method according to claim 1 or 2, characterized in that the dispersion or emulsion to be homogenized before entering the grinding chamber (5) a shear stress between rotating surfaces (13, 14) on the outside of the wall elements (2, 4 ) of the grinding chamber (5) is subjected.

4. The method according to claim 1, 2 or 3, characterized gekenn¬ characterized in that the homogenized mixture is withdrawn via an axial channel (17).

5. The method according to any one of claims 1 to 4, characterized ge indicates that the grinding chamber (5) to a maximum of 75 vol .-%, preferably 60 vol .-%, with grinding media (19) of an effective diameter of less than 0.5 mm, preferably less than 0.1 mm, is filled.

6. The method according to any one of claims 1 to 5, characterized gekenn¬ characterized in that the mixing process between relative to each other with different speed and / or direction of rotation ro¬ rotating wall elements (2,4) is carried out.

7. Device for performing the method according to one of claims 1 to 6 with a grinding chamber (5), in which Mahl¬ body (19) are arranged, characterized in that the grinding chamber (5) of at least two wall elements (2,4) is limited, which can be driven rotatably, and that the grinding chamber (5) has at least one feed and / or discharge opening (15, 16, 17) on its sides facing and facing away from the axis (s) of rotation (3, 18). having.

8. The device according to claim 7, characterized in that the supply and the discharge openings (15, 16) of ge over the circumference of the grinding chamber (5) extending slots are formed.

9. The device according to claim 8, characterized in that the slots (15,16) in a common, substantially on the axis of rotation (n) (3.18) of the wall elements (2.4) normal to the parting plane of the grinding chamber (5).

10. The device according to claim 7, 8 or 9, characterized gekenn¬ characterized in that the wall elements (2.4) of the grinding chamber (5) limited grinding chamber in at least one

Cross-sectional plane containing the axis of rotation (3.18) transverse to this. Rotation axis is tapered in cross section.

11. Device according to one of claims 7 to 10, characterized in that the wall elements (2.4) are formed by half-shells which are rotatably mounted about a common axis (3) and are connected to separate drives.

12. Device according to one of claims 7 to 10, characterized in that the axes of rotation (3,18) of the Wand¬ elements (2,4) are arranged inclined relative to each other and

,. Connect together at an obtuse angle.

13. Device according to one of claims 7 to 10, characterized in that the angle between the axes of rotation (3,18) of the wall elements (2,4) is infinitely adjustable. 0

14. The device according to one of claims 7 to 13, characterized in that a wall element (2) with a the second wall element (4) forming a gap (12) overlapping part (7) is rotatably connected and that Lead (11) opens into this gap (12). 5

0

5