ES2211470T3 - SPHERICAL MIXER. - Google Patents

Abstract

The mixer has a transmission tube (70) mounted in rotation, a first axle (80) mounted in rotation inside the transmission tu and a second axle (76) mounted in rotation at the end of the transmission tube and supporting the mixing device (78). The second axle forms an angle alpha with the axis of the transmission tube and is driven in rotation about its own axis by the rotation the first axle. Preferred Features: The angle alpha is 45-90 degrees . The orientation of the mixing device can be varied relative to the second axle during its rotation and are in the form of segments of a circle. A first motor (66) drives the first axle and a seco motor (68) drives the transmission tube. The second axle is driven by the first axle via a gear. An Independent claim is also included for a mixing apparatus containing a mixer as above and a receiver (60) with a symmetr revolution described by the edge of the mixing device. The receiver has an outlet drain in its base.

Description

Spherical mixer

The present invention aims at a device intended for mixing and / or homogenization of a medium heterogeneous.

Mixers are used to mix several components. These can be gaseous, liquid or solid, and miscible or not miscible. Mixing is an operation that intervenes in all types of industry, which gives it importance considerable.

"Mechanical unit operations", point to multicopista of the class of second course taught by Noël Midoux at the National Higher School of Chemical Industries (E.N.S.I.C.), 1989, describes mixers comprising a tree at They are subject mixing organs. The organs may present various shapes, such as blades, propellers, anchors, screws or tapes The tree is driven in rotation by means of drive Mixer mixing organs are immersed in a container containing the medium to be mixed. Being variable in the middle the speed of movement conferred on the medium, the mixture of the heterogeneous medium is obtained. The tree can soak vertically in the bowl with mixing organs rotating horizontally, or it can be introduced laterally in the bowl and the organs rotate vertically. For certain applications, the tree can lean to rest on the edge of the tank. In all cases described in this document, the mixing organs revolve around the axis defined by the tree.

Mixers are also known that consist of two axes Similarly, some kitchen robots comprise a Little Cuba The rotation movement of the central tree is then transmits on the one hand to a second tree displaced from such that it makes a planetary displacement around the central tree; the mixing organs are mounted on the second tree, so that they are actuated in rotation around said second tree at the same time as the tree describes a circle.

The document EP-A-0 325 865 describes a mixer, which features a motor mounted on the deck of a Cuba, a first vertical shaft driven in rotation by the engine, a second vertical tree, supported by the first tree and rotating around it, and a third horizontal tree supported by the second tree in which mixing organs are mounted. Saying mixer works in a flat bottomed bowl, and is designed to such that the mixing organs sweep the bottom of the tank without Leave no dead zone.

The invention aims to improve the performance of existing mixers. The invention has also to solve the new problem that constitute the dead zones in the mixers. Indeed, if the mixer does not is adapted to the geometry of the container, there are calls dead zones, in which the medium is at rest. In said zones, no mixing takes place. It is also possible that a mixed volume found in one of these dead zones is separate again. This problem occurs especially in the lower corners of cylindrical containers, for example. East problem of dead zones and the uniformity of the mixture is even more sensitive when it comes to mixing a viscous medium or of Mix at low speed. In such cases, the effects of the mixture They are limited in the area swept by the mixing organs. For the therefore, a non-uniform mixture can be obtained when the mixer does not It is adapted to the geometry of the container. The invention proposes a solution to this problem of dead zones, especially in the case of spherical containers.

The document EP-A-0 325 865 proposes a solution to the problem of dead zones, which fits for a container flat bottom. However, the solution proposed in said document is not necessarily satisfactory for the part of above the product that must be mixed; little areas may remain or nothing mixed in the top of the container.

Moreover, the documents FR-A-403214, DE-B-1 049 672 and GB-A-2 237 752 describe mixers that have a rotating mounted transmission tube with a first rotating shaft that extends inside the tube of transmission and a second shaft mounted by rotation in the end of the transmission tube and that supports mixing organs in those that the second tree forms an angle with the axis of the tube of transmission and is driven in rotation around its own axis by the rotation of the first tree.

The mixer of the invention is also specially adapted to the mixture of non-miscible components of different density; allows to avoid the separation of the components of the mixture under the effect of the density difference of the components. The mixer of the invention is also adapted to the mixture of a medium containing fragile components whose texture You want to keep.

The invention also allows a mixing in a container, continuing the operation of mixing or homogenization until complete emptying of the container. Avoid an untimely incorporation of air into the mixture, as well as splashes, which cause fouling that can cause immobilization of the device to perform annoying cleaning.

The invention applies to the mixing of media all kinds, and in particular, of viscous or powdered media. The mixer of the invention is specially adapted for the maintenance of unstable mixtures, even when they present fragile components Finally, the mixer according to the invention It is especially advantageous because it can adapt to the geometry of containers of different form. In addition, the mixer of the invention allows to maintain the mixing or homogenization action until complete emptying of the container. Guarantees a mix especially uniform and also prevents splashing and incorporation of air in the mixture.

The invention proposes a mixer as is described in claim 1.

Preferably, the angle between the second tree and the transmission tube is between 45 ° and 90 °.

The mixing organs have an orientation with respect to the second variable tree along the rotation of East.

In the embodiment, the mixing organs they have an end edge in the form of a circle segment.

A first engine can also be provided that rotates the first shaft and a second motor that drives in rotation the transmission tube.

It is also possible that the second tree is driven in rotation by the first tree through a gear.

The invention also proposes a mixing apparatus comprising a mixer of this type and a container whose bottom presents a symmetry of revolution and whose generator is the edge of end of a mixing organ.

Advantageously, the container has a bottom drain opening. You can choose then said angle so that the end of a mixing organ sweeps the drain opening.

In a last embodiment, the apparatus it also has an inner frame that supports the container and the mixer and that is mounted on a rotating outer frame according to a common diameter of the inner and outer frames, and a support, the outer frame being mounted in rotation according to a diameter on said support.

Other features and advantages of the invention will be revealed by reading the following description of modes of embodiment of the invention, given by way of example and with reference to the attached drawings in which:

Figure 1 is a schematic diagram of a mixer according to the invention with its container;

Figure 2 is a sectional view of a mixer according to a first embodiment of the invention;

Figure 3 is a top view of the mixer of figure 2;

Figure 4 is an enlarged view of a mixer according to an embodiment of the invention;

Figure 5 is an other view of embodiment of the invention;

Figure 6 is an other view of embodiment of the invention.

In order to improve the performance of known mixers, the invention proposes to arrange the organs of rotating mixture on a tree that rotates in the middle, and that is oriented according to a substantially horizontal direction. This shape, avoid any dead zone in the container in which it effect mixing, without there being any fixed point of the Mixing organs near the wall of the container.

In the embodiment of Figures 1 to 5, the tree on which the mixing organs are arranged is supported by a noticeably vertical tree, which is actuated in a rotation movement over a circle. The kinematics is of same type as the document EP-A-0 325 865, although the invention suggests improvements in the principle proposed in that document.

In the embodiment of Figure 6, the tree on which the mixing organs are arranged is supported by a noticeably vertical tree, which is actuated in rotation around its own axis. Said embodiment allows to simplify considerably the structure proposed in the EP-A-0 325 865, and in Specially, it simplifies the drive mechanism.

Figure 1 shows a schematic diagram of a mixer according to the invention. The mixer presents a first tree 1 substantially vertical, which supports the mixing organs and that, As the arrow symbolizes, it is actuated in rotation. In its lower end, tree 1 supports a second tree 2. In mode of embodiment of figure 2, the shaft 2 is substantially vertical, and is offset with respect to the first tree. The second tree 2 it is driven in rotation around the first tree 1. The second tree 2 carries at its lower end a third tree 3 oriented according to a substantially horizontal direction. Tree 3 carries the mixing organs, represented here in the form of blades 4 and 5. These blades are driven in rotation around the third tree and allow mixing of the medium in the container 6. The Blade orientation varies with the angle of rotation, as explained with reference to figure 4.

Thus, when the mixer of the invention is in operation, the mixing organs move in rotation around a substantially horizontal axis, said axis being in rotation in the middle.

Thus, the first tree 1 is driven in rotation by drive means. The second tree 2 is actuated in rotation around the first tree 1, but also around same. The second tree 2 carries at its lower end a third 3 substantially horizontal tree that supports the mixing organs. The third tree 3 is driven in rotation, which causes a rotation of mixing organs. The preferred embodiment provides for the drive of the three trees by a single engine coupled to tree 1. However, it can be equally advantageous provide for an independent drive from another shaft or even from All the trees In addition, if satellite movement is considered of tree 2 around tree 1, it can be seen that the ends of the mixing organs describe a sphere when the center of rotation of the mixing organs coincides with the axis of tree 1, and a bull in cases where said center is displaced with respect to to that axis. Rotation center is understood as the intersection between the axes of symmetry of the blades -if they exist- and the third tree.

As the figure shows, the shape of the blades 4 and 5 can be adapted to the shape of the container, so that it Minimize dead zones in the container. Due to rotation around the third axis substantially horizontal, there is no fixed point near the wall of the container. Due to the rotation of the second tree around the third tree, the third tree is powered on rotation in the container, and the axis of rotation of the organs of Mix rotates in the bowl. The bottom of the container according to the invention thus presents a symmetry of revolution -Around the axis of the first tree- and its generator is the edge of end of mixing organs; in the example, the background of container is spherical and the edge of the blades is an arc of circle.

In the embodiment of Figure 1, each one of the mixing organs is symmetrical with respect to a line. The intersection between said line and tree 3 is over the axis of the first tree 1, symbolized in the figure with a stroke of points. This configuration is particularly advantageous when mixing organs are actuated in rotation on themselves apart  of its rotation around the tree 3.

It is also possible that the mixing organs do not are in the axis of the first tree 1. This can also be advantageous to increase the volume swept by the organs of mixture.

Figure 2 shows a cross-sectional view of a mixer according to a first embodiment of the invention; in the embodiment of figure 2, the movement of the second tree around the first and the movement of the organs of mix around the third tree are guaranteed by means of single drive; said single drive means actuate rotating the first tree, which is the advantage that drive means are not moving while the mixer.

In figure 2 the different ones can be observed elements already described with reference to figure 1, and especially the first tree 1; said tree is driven in rotation by means drive - for example, a speed gearmotor variable- not shown in the figure. At the bottom of the first shaft is mounted in rotation a support 10, in which the Second tree 2 is mounted in rotation. The support 10 maintains the position of the second tree with respect to the first tree, allowing the rotation of the second tree around the First.

A first gear wheel 11 is mounted on rotation around the first tree, and remains fixed with respect to the container 6 by a pivot interlock 12. Of this mode, the cogwheel is fixed. A second cogwheel 13 is fixed on the second shaft 2 and engaged in the first gearwheel. The first and second wheels form a first gear.

A third gearwheel 15 is fastened in the First tree A fourth cogwheel 16 held in the second Tree is engaged in the third gear wheel. The third and the Fourth cogwheel form a second gear.

The support system 10, the first and the second Gears are arranged in a crankcase 19.

The operation of the elements just Describe is as follows. The rotation of the first tree 1 is transmitted to the second shaft 2 by means of the second gear; due to the first gear, the second shaft is driven in rotation around the first tree. The choice of the number of teeth from the first to the fourth cogwheel allows to regulate the own rotation speed of the second tree, and the speed of rotation of the second tree around the first tree.

On the lower side of the support 10 is fixed vertically a transmission tube 25 that wraps the second shaft 2. At the lower end of the transmission tube 25 is fixed a carter 40, in which the lower end of the second Tree is mounted in rotation. At the lower end of the second tree is fixed a fifth cogwheel 27 with conical teeth. The third shaft 3 is mounted in rotation on crankcase 40, and carries on its end a sixth cogwheel 28, with conical teeth, which is engaged in the fifth gear wheel. The fifth and sixth wheel Toothed form a third gear.

Blades 4 and 5 are subject in the third tree.

In this way, the rotation movement of the support 10 rotates the crankcase 40 around the first tree 1. The proper rotation movement of the second tree 2 is transmitted to the third shaft 3 by the third gear, and drives Mixing organs The choice of the relation of the numbers of teeth in the third gear allows to regulate the speeds of own rotation of the second and third tree.

In the illustrated embodiment, the organs mixing are mounted on rods 21 and 22 and are symmetrical with respect to the axis of said rods. The intersection point of the rods and the third tree is located on the axis of the first tree 1. The number and shape of the blades depend on the problem of mix to solve. In the embodiment illustrated in the Figures 2 and 3 are provided 4 blades. The orientation of the different blades vary with the angle of rotation, as explained with reference to figure 4.

Consequently, the mixing organs effect at the same time a vertical rotation movement, around the third tree, which performs a horizontal rotation movement in the fluid If the centers of these two rotations are cut, these movements originate a movement on a sphere of each one of the points of the mixing organs. According to the mode of recommended embodiment, the center of rotation of the organs of mixture is found in the extension of the axis of the first tree, and the ends of the. It is also possible that the mixing organs are not in the extension of tree 2, but are horizontally displaced. In this case, each point of an organ Mixing moves over a bull. According to one embodiment advantageously, the shape of the mixing organs adapts to the bottom geometry of the container used. The organs in the that the curvature of the ends corresponds to a segment of circle are particularly advantageous. This allows to obtain a optimal mixing efficiency to the extent that areas are avoided dead in containers with spherical bottom or similar.

Figure 3 shows a top view of the mixer of figure 2. The first one can be seen in figure 3 shaft 1, the first cogwheel 11 with the pivot interlock 12, the second cogwheel 13, the third cogwheel 15 and the fourth cogwheel 16. The blades are also shown in the figure 4 and 5, with support rods 21 and 22. Arrows 31 and 32 indicate the rotation of the support 10 and the third shaft around the First tree Arrows 33 and 34 indicate the rotations of the third and fourth gear 15 and 16. Arrows 35 and 36 indicate the rotation of the second cogwheel, and the rotation of the Second tree around the first tree.

According to the preferred embodiment of the Figures 2 and 3, the relative rotation speed of the three trees is fixed, and is determined by the relationships of different gears However, it can also result It is advantageous to provide means for varying said speeds.  respective. In this case, drive means may be provided. independent for each of the trees. A control by Computer of different engines can also be advantageous, for example, when you want to vary speeds during the Mix or frequently.

Figure 4 shows the device according to the invention that includes a cam system that allows modifying the orientation of the mixing organs according to the angle of rotation of the third tree.

To this end, it is planned, inside the third tree 3, a fourth tree 41, which is fixed with respect to the crankcase 40, as symbolized by joint 42 at the end of said Fourth tree At its far end of the crankcase, the fourth tree It has a wheel 44, which has a path on its perimeter rolling 45 having an axial extension along the axis of the Fourth tree

In the embodiment of Figure 4, the shovels are mounted in rotation on the third tree; Like it shows the figure, the rod 21 of the blade 4 is mounted in rotation in a radial hole 47 of the third tree.

At its opposite end to the blade, the rod 21 presents an off-center follower 49, which rolls down the path of rolling 45 of the wheel 44. The angular position of the rod 21 with respect to the third tree and therefore the angular position of the blade 4 around the rod 21 depend on the position of the follower 49.

The device of Figure 4 works from the following form. The rods 21 or 22 and the corresponding blades they are driven in rotation around the axis of the third tree 3 by the rotation of the third tree with respect to the crankcase 40, due to the concomitant rotation of the holes in which they are mounted the rods During this rotation, the followers 49 roll by the raceway and, because the raceway is extends in different positions along the axis of the room tree, these followers vary the angular position of the rods and, therefore, of the blades.

The device of Figure 4 thus allows modify the angle between the blades and the third tree during the Rotation of the blades around the axis of the third tree. One Way proper rolling allows, for example, to bring in the mixing organs to bias in the middle to mix and make them come out of new to blade, that is, perpendicular to the surface, with in order to minimize splashes and the incorporation of air. A variation of 45º between the angle between the plane of a mixing organ and the third tree, on the one hand, and between the plane of an adjacent mixing organ and the third tree, on the other part, it also constitutes an advantageous provision to the extent in which it causes a wave effect while dragging the product by A background movement.

Figure 5 shows another embodiment of the invention; in said embodiment of the invention, the mixer assembly and its container is mounted on two concentric racks 51 and 52. The inner frame supports the bowl and mixer; the mixer stand is not represented in the figure. The inner frame is mounted on the outer frame in rotation according to a common diameter of the indoor and outdoor racks; in the figure, said diameter is perpendicular to the plane of the sheet. The outer frame is mounted in rotation on a support 53, in rotation according to a diameter of the outer frame perpendicular to the diameter in which it is mounted the inner frame. The set of the two racks allows place the bowl and mixer at any angle. The Figure also shows the drain opening 54 located in the container base The orientation of the blades varies with the rotation angle, as explained with reference to the figure Four.

In the embodiment of the figure, the two racks are concentric at a point that is the intersection of the axes of the first and the third tree. You could also choose another fixed point for the whole mixers.

The assembly of figure 5 allows combining a rotating movement of the container and mixer with the movement of mixing organs. In this way, the dead masses and the deposit of mixed material on the walls of the container. This allows, especially, to avoid the use of a scraper

The device of the invention is adapted to the fast and efficient mixing of liquid or solid materials, by example powders. The results of mixing tests in an apparatus of the type illustrated in Figures 2 and 3, for a mixture of saccharin in powdered milk or flour.

In the first test, 100 g of saccharin and 8679 g of milk powder in the mixer, for 180 seconds. Then, three samples were taken from different areas of the Mixing vessel and analyzed. The test results they are shown in table 1.

Saccharin (g) Milk powder (g) % 0.10 10.75 0.93 0.13 10.86 1.19 0.11 10.85 1.01

These values should be compared with the percentage nominal 1.15% saccharin in milk powder. They show that the Mixing is very homogeneous after a short mixing time.

In the second test, 100 g of saccharin and 10454 g of flour in the mixer, for 240 seconds. Then, three samples were taken from different areas of the container of mixture and analyzed. The test results are shown. in table 1.

Saccharin (g) Flour (g) % 0.075 11.09 0.67 0.057 10.49 0.54 0.064 10.48 0.61

These values should be compared again with the Nominal percentage of 0.95% saccharin in flour. Sayings values are indicative of the separation of the components, which are it reaches after a very weak mixing time. Indeed, it is known that prolonged mixing may cause separation of initial components: said separation is generally carried out after a mixing time much greater than 240 seconds.

The mixer of the invention has turned out to be particularly adapted to the manufacture of jams. Thus frequently observe that, at rest, the pieces of fruit, of lower density, the surface of the mass of jam. Therefore, it is necessary to homogenize the mixture continuously during conditioning, to obtain a homogeneous final product, that is, an equivalent amount of pieces of fruit in each jar of jam. However, in the cited example, it is desired to preserve the texture of the pieces of fruit despite the mixture, so it is important that the mixture be done carefully, without destroying the texture of the pieces of fruit, without incorporation of air and without splashes. The mixer of the invention has allowed to obtain a high homogeneity of the distribution of fruit pieces, while retaining the texture of these.

Figure 6 shows another embodiment of the mixer according to the invention. In said embodiment, such as indicated above, the tree in which they are arranged the mixing organs is supported by a tree substantially vertical, which is rotated around its  own shaft More precisely, in figure 6 the container 60, provided with a cover 62 which has means of product admission. As in the described embodiments above, the bottom of the container is spherical and has a opening. On the deck a crankcase 64 is mounted, on which they are subject two engines 66 and 68. The first engine allows to regulate the rotation speed of mixing organs around their axis of rotation, while the second motor allows to regulate the rotation speed of the shaft that supports the mixing organs around the axis of symmetry of the container. The presence of two engines allows to regulate these two speeds separately angular as described above, a single engine and a gear system to guarantee both rotations This last solution has the advantage of using a single engine, however, makes variations more complex Relative rotation speeds.

A tube is mounted in rotation under the cover transmission 70; in the figure, we can see the bearings that They support the transmission tube. The transmission tube is driven in rotation by the second motor 68, by means of a two-wheel gear 72 and 74. In the example, the tube transmission has an axis of rotation that is confused with the axis of symmetry of the container, although this is not essential for the application of the invention, and could be otherwise, especially in the case of a flat bottom container. In its lower end, the transmission tube rotates the tree 76 that carries mixing organs 78. As the figure, the axis of said tree is inclined with respect to the tube of transmission at an angle? which, in the mode of realization of the figure, is close to 78.5º. More generally, it is advantageous that said angle is between 45 ° and 90 °. The upper limit of this interval depends on the size of the organs of mixture that, as the figure shows, must pass near the tube transmission on the top of the mixer, in the case of a 90º angle, the mixing organs advantageously have a variable orientation, so that they move away when passing near the transmission tube, as explained below. If the orientation of the mixing organs is fixed, it is advantageous to select the size  of the mixing organs and the orientation of the second tree of such so that the mixing organs pass as close as possible to the tube; This guarantees a good sweep of the bottom of the container.

The lower limit of this interval guarantees that the mixing organs sweep the bottom of the container, especially near its emptying point. Rotation of transmission tube under the second motor drive guarantees that the shaft 76 is driven in rotation around the shaft of the transmission tube.

In addition to said rotation movement, the tree 76 which carries the mixing organs is driven in rotation in around its own axis. To this end, the mixer presents a tree 80 mounted in rotation inside the transmission tube, which It is driven in rotation by the first motor. At its end lower, said shaft is provided with a conical cogwheel 82, engaged in a cogwheel 84 mounted on the shaft 76.

The operation of the mixer of Figure 6 is the next. Tree 80 or first tree is driven in rotation, and rotates around its axis. At the same time, the transmission tube It revolves around the axis of the first tree. Due to the rotation of the transmission tube, tree 76 or second tree is driven in rotation around the shaft of the shaft 80 and the transmission tube. Simultaneously, the rotation of the first tree 80 guarantees the Rotating drive of the second shaft around its own axis. In this way, as in the first embodiment of the invention, the mixing organs are driven in rotation around a substantially horizontal axis, meeting this same axis in rotation in the middle.

As the figure shows, and as in the preceding embodiments, the shape of the mixing organs can be adapted to the shape of the container, in order to minimize the dead zones in the container. Due to the rotation around of the second axis substantially horizontal, there is no point fixed near the wall of the container, especially near the bottom of the container. Due to the rotation of the second tree around the axis of the first tree, the second tree is driven in rotation in the container, and the axis of rotation of the mixing organs rotates In the container. The bottom of the container according to the invention it presents, therefore, a symmetry of revolution - around axis of the first tree- and its generator is the end edge of the mixing organs; In the example, the bottom of the container is spherical and the edge of the blades is a circle arc.

The embodiment of Figure 6, with with respect to the preceding embodiments, it allows simplify the structure of the mixer, and especially the number of moving parts. Said embodiment maintains the advantages described with reference to the preceding figures, such such as the absence of dead zones and the quality of the mixture. The Orientation of the mixing organs varies throughout the rotation around the second tree, as explained with reference to figure 4. In this case, due to the asymmetry of the mixing organs, it is convenient to pay attention to the orientation of these near the bottom of the container.

It will be noted that the set of moving parts is found either in the container, or in the crankcase of the cover.

It is clear that the present invention is not limited to the examples and embodiments described and represented, but is susceptible to numerous variants accessible to the expert in this field. Similarly, it is evident that the invention is not limited to the recommended embodiment. In  in particular, in the described embodiments, the whole of the movement is transmitted to the different parts of the mixer by middle of the first tree; This solution has the advantage of allow the mixer drive motor to be mounted on a fixed position, which limits the moving masses. Could also provide a first fixed shaft and a motor that drives the second tree. In the described embodiments, the trees are perpendicular; it could also be expected that the second tree be inclined with respect to the first tree, for example, to Increase the volume swept by the mixing organs.

Although this is not described in detail, it can apply the teaching of figure 5 - a set of two concentric racks - to the mixer of figure 6 or, on the other part, to another type of mixers.

In the embodiment of Figure 6, the tube transmission could be extended to below the second tree. However, this would not have functional incidence and even in that case, the second tree would be found functionally in the end of the transmission tube; indeed, the tube part of transmission protruding beyond the second tree does not intervene in the drive.

Claims (9)

1. Mixer, comprising a transmission tube (70) mounted in rotation, a first shaft (80) mounted in rotation inside the transmission tube, a second shaft (76) mounted in rotation at the end of the transmission tube and which supports the mixing members (78), the second shaft (76) forming an angle (?) with the axis of the transmission tube and being driven in rotation around its own axis by the rotation of the first shaft, characterized in that The mixing organs (78) have an orientation with respect to the second variable shaft (76) during its rotation. 2. The mixer of claim 1, characterized in that the angle (?) Between the second shaft and the transmission tube is between 45 ° and 90 °. 3. The mixer of claim 1 or 2, characterized in that the mixing members (78) have an end edge in the form of a circle segment. 4. The mixer of one of claims 1 to 3, characterized by a first motor (66) that drives the first shaft (80) in rotation and a second motor (68) that drives the transmission tube (70) in rotation. . 5. The mixer of one of claims 1 to 4, characterized in that the second shaft (76) is driven in rotation by the first shaft through a gear (82, 84). 6. A mixing apparatus comprising a mixer according to any one of claims 1 to 5, and a vessel (60) whose bottom has a symmetry of revolution and whose generator is the end edge of a mixing organ. 7. The apparatus of claim 6, characterized in that the container has a drain opening in the bottom. 8. The apparatus of claim 7, characterized in that said angle is selected such that the end of a mixing member sweeps the drain opening. The apparatus of claim 6, 7 or 8, characterized in that it also has an inner frame (51) that supports the container and the mixer, and mounted on an outer frame (52) in rotation according to a common diameter of the inner and outer frames, and a support (53), the outer frame being mounted in rotation according to a diameter on said support (53).