Patent Publication Number: US-7217029-B2

Title: Mixer with lump breaker having multiple axes of rotation

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a mixer and an apparatus comprising the mixer. 
     Mixers are used for mixing several components. The latter can be gaseous, liquid or solid and miscible or non-miscible. Mixing is an operation which occurs in all types of industry, which gives it considerable importance. 
     EP-A-0,325,865 discloses a mixer for mixing cooking ingredients. This mixer comprises a mixing device in the form of a recumbent U, comprising two upper and lower horizontal branches, connected to each other at one of their ends by a vertical branch. The lower horizontal branch comprises a vane for mixing the ingredients. The device is driven in rotation by a vertical shaft at the free end of the upper horizontal branch. The rotation of the recumbent U by the vertical shaft effects the rotation of the vane about a horizontal axis by a transmission in the U. This mixer has the drawback that the ingredients are not only mixed by the vane but also by the other branches of the U which beat the ingredients during their rotation about the vertical shaft. Consequently, mixing is difficult to control and not uniform. 
     FR-A-2,336,168 discloses a mixer. According to one embodiment, the mixer comprises a first, substantially vertical, shaft driven in rotation about its vertical axis and driving a second shaft about an axis that is inclined relative to the axis of the first shaft. The second shaft is driven by the first shaft via an angular member in the centre of a sphere. The second shaft carries a stirring member. A movement of the assembly about the axis of the vertical shaft can result only from the torque caused by the rotation of the stirring member about the second shaft. The drawback is that the rotation of the assembly about the axis of the vertical shaft is not controlled; the rotation is influenced by the quantity and viscosity of the ingredients in the vessel. Consequently, the mixing is difficult to control and not uniform. 
     SUMMARY OF THE INVENTION 
     There is therefore a need for a mixer which makes it possible to improve mixing. 
     For this purpose, the invention provides a mixer comprising:
         a casing substantially having symmetry of revolution about a first axis,   mixing members driven in rotation relative to the casing and about a second axis that is inclined relative to the first axis,
 
the casing and the mixing members being driven in rotation about the first axis at a determined speed.
       

     According to one embodiment, the casing can comprise a cap driven in rotation about the second axis and supporting the mixing members. 
     According to one embodiment, the mixer can comprise a first drive unit for driving the casing and the mixing members about the first axis and a second drive unit for driving the mixing members about the second axis. In this case, the first and second drive units can be superposed along the first axis. 
     According to one embodiment, the second axis can be inclined relative to the first axis at an angle comprised between 45° and 90° in the trigonometric sense. 
     According to one embodiment, the mixing members can have an orientation which is variable relative to the second axis. 
     According to another embodiment, the mixing members can have an orientation which is fixed relative to the second axis. 
     Advantageously, the mixing members can have an extreme edge in the shape of an arc of a circle. 
     According to yet another embodiment, the mixer can comprise:
         a transmission tube driven in rotation about the first axis and carrying at one end the casing,   a first shaft, in the transmission tube, driven in rotation about the first axis,   a second shaft driven in rotation about the second axis by the first shaft, the second shaft driving in rotation the mixing members,   a transmission connecting the first and second shaft, the transmission being in the casing,       

     According to one embodiment, the mixing members can be open-worked vanes, solid vanes or cutters. 
     According to another embodiment, the mixer can comprise a lump breaker which is mobile relative to the first axis, the lump breaker and the mixing members being on either side of a plane containing the first axis. 
     Advantageously, the lump breaker can be mobile parallel to the first axis. 
     Preferably, the lump breaker can be along the second axis. In this case, the lump breaker can be connected to the transmission tube. For example, a telescopic arm can connect the lump breaker to the transmission tube. 
     Advantageously, the lump breaker can be driven in rotation by a motor in the telescopic arm. 
     The invention also relates to an apparatus comprising a mixer as described previously, and a container, the base of which has a symmetry of revolution and the generatrix of which is the extreme edge of a mixing member. 
     According to one embodiment, the apparatus can moreover have an inner cradle supporting the container and the mixer and mounted on an outer cradle in rotation about a diameter common to the inner and outer cradles, and a support, the outer cradle being mounted in rotation about a diameter on said support. 
     Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, of the embodiments of the invention, given by way of example only, and with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 , a view of the mixer according to the invention; 
         FIG. 2 , a sectional view of the mixer of  FIG. 1  according to one embodiment; 
         FIG. 3 , a diagrammatic top view of the mixer of  FIG. 2 ; 
         FIGS. 4 to 8 , views of a lump breaker; 
         FIGS. 9 and 10 , views of joints; 
         FIG. 11 , a view of the apparatus according to an embodiment of the invention 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention proposes, in order to improve the performance of known mixers, driving in rotation mixing members relative to a casing which has substantially a symmetry of revolution about an axis. The casing and the mixing members are also driving in rotation in the medium about said axis. In this way, the mixing members are responsible for mixing the ingredients and the mixing is controlled throughout the medium. 
       FIG. 1  shows a view of the mixer  10 , in a container  30 .  FIG. 1  shows the mixer  10  comprising a casing  20  leaving substantially symmetry of revolution about a first axis  13 . The first axis  13  is substantially vertical. In the figure, the casing  20  is non-limitatively represented with a spherical shape. The mixer  10  also comprises mixing members  22  driven in rotation relative to the casing  20 . The mixing members  22  are driven in rotation about a second axis  15  inclined at an angle α relative to the first axis  13 . The casing  20  and the mixing members  22  are driven in rotation about the first axis  13  at a determined speed. 
     The mixing members  22  make it possible to beat the ingredients present in the container  30 . The mixing members  22  are driven simultaneously about the second axis  15  in a rotation movement υ and about the second axis  13  in a rotation movement θ. This makes it possible, during the operation of the mixer  10 , to improve the mixing of the ingredients throughout the container. The mixer makes it possible to avoid dead zones in the container  30  where the ingredients are not mixed. 
     The second axis  15  is inclined relative to the first axis  13  at an angle α comprised between 45° and 135° in the trigonometric sense. The inclination of the second axis  15  allows the mixing members to move in a zone situated vertical to the first axis  13  and to beat the ingredients which are found in this zone. This avoids leaving a dead zone below the first axis  13 . 
     The casing  20  makes it possible to keep the mixing members  22  inside the container  30 . The casing  20  encloses the means used for driving the mixing members  22 . The casing  20  has substantially a symmetry of revolution about the first axis  13 . Thus, the casing  20  does not have asymmetries such that, during the rotation of the casing  20  according to θ, the asymmetries would contribute to the mixing of the ingredients. The advantage of the invention is that the mixing members are responsible for the mixing. The mixing is thus better controlled. 
     In order to obtain better mixing, the casing  20  and the mixing members  22  are driven in rotation about the first axis  13  at a determined speed. The speed is determined in the sense that the user himself fixes the speed of rotation about the axis  13 . The speed does not depend on the ingredients present in the container  30 . The rotation about the axis  13  is not passive as the rotation is not engendered solely by the fact of the rotation of the mixing members  22 . On the contrary, the rotation about the axis  13  is engendered by an active drive. Thus, contrary to the document FR-A-2 336 168, in which the rotation of the mixing members themselves causes the rotation of the assembly in the container, the rotation of the assembly according to the invention is fixed by the user. The rotation at a determined speed of the casing  20  and the mixing members  22  can be for example engendered by drive units as described above in connection with  FIG. 2 . 
     The driving of the casing  20  and the mixing members  22  will now be explained in more detail and in non-limitative fashion according to the embodiment of  FIG. 2 .  FIG. 2  represents a sectional view of a mixer according to one embodiment. 
       FIG. 2  shows the various parts already described in  FIG. 1 . It shows in particular the first axis  13  and second axis  15 , the casing  20  and the mixing members  22 . Moreover, the mixer  10  comprises a transmission tube  12  driven in rotation about the first axis  13 . The transmission tube  12  comprises at one end  12   a  the casing  20 . In the transmission tube  12 , a first shaft  14  is driven in rotation about the first axis  13 . The mixer  10  comprises moreover a second shaft  16  driven in rotation about the second axis  15  by the first shaft  14 . The second shaft  16  drives in rotation the mixing members  22 . A transmission  18  connects the first shaft  14  and the second shaft  16  in such a way as to allow the driving of the shaft  16  by the shaft  14 . The transmission  18  is in the casing  20 . 
     Thus the rotation of the transmission tube engenders the rotation of the casing  20  and the mixing members  22  according to the movement referenced θ. The mixing members  22  are also driven in rotation according to the movement υ. The mixing members  22  are driven by this movement thanks to the rotation of the first shaft  14  driving in rotation the second shaft  16  by the transmission  18 . The transmission tube  12  is driven in rotation by a drive unit  32 , and the first shaft  14  is driven in rotation by a drive unit  34 . 
     The first unit  32  drives the casing  20  and the mixing members  22  about the axis  13  and the second unit  34  drives the mixing members  22  about the axis  15 . The units  32 ,  34  allow the casing  20  and the mixing members  22  to be driven at a determined speed. Thus, the determined speed of rotation of the casing  20  and the mixing members  22  makes it possible to improve the mixing of the ingredients. 
     Advantageously, the drive units  32 ,  34  are arranged one above the other in such a way as to facilitate the maintenance and cleaning of the mixer. For this purpose, the shaft  14  extends beyond the end  12   b  of the transmission tube  12  along the axis  13 . This allows the unit  34  to drive the shaft  14  and allows the unit  34  to be arranged above the unit  32 . 
     The superposed arrangement of the drive units  32 ,  34  makes it possible to dispense with bearings between the transmission tube  12  and the container  30 . In fact, the drive unit  32  can be fixed to the container  30  itself, which allows the transmission tube to dip into the container without being guided relative to the container  30  by bearings. 
     Another advantage of the superposition is that the units  32 ,  34  directly drive the casing  20  and the mixing members  22  without the need for a belt or gear drive. The advantage is the ability to remove and replace the mixer more easily in order to carry out a maintenance operation. In fact, the unscrewing of a nut  50  at the top of the column comprising the drive units  32 ,  34  and the casing  20  allows this assembly to drop down and be maintained and cleaned. 
     The drive unit  32  is for example a motor which can drive the transmission tube up to a speed of 8 rpm. The drive unit  34  is for example a motor which can drive the shaft  14  up to a speed of 30 rpm. 
     According to one embodiment, the mixer  10  comprises a cap  36  supporting the mixing members  22 . The cap  36  is driven in rotation about the second axis  15 . The cap  36  is part of the casing  20  and fits into the symmetry of revolution of the casing  20  about the axis  13  so as not to disturb the mixing by the mixing members  22 . The orientation of the mixing members  22  can vary relative to the second axis  15 . The advantage is the ability to adjust the orientation of the mixing members as a function of the products to be mixed and in particular their viscosity. Preferably, the orientation of the mixing members is fixed relative to the second axis  15 . For this purpose, the mixing members  22  can be made in one piece with the cap  36 , the assembly being obtained for example by moulding. The advantage is that the moulding of the assembly makes it possible to preserve this invariable orientation over time, which allows better control of the mixing. 
     The transmission  18  makes it possible to turn the mixing members  22  about the second axis  15  without the drive unit being close to the mixing members  22 . This makes it possible to move the drive unit outside the container  30 . The advantage is ability to choose the power of the drive unit as well as its subsequent overall dimension regardless of the size of the container  30  and vice versa. The length of the first shaft  14  can be adjusted as a function of the desired position of the mixing members  22  in the container  30 . The transmission  18  allows transmission of the rotation movement of the first shaft  14  to the second shaft  16 . The transmission  18  is for example a gear system. The a gear system is for example of the bevel gear type The advantage of the bevel gearing is the ability to incline the axis  15  relative to the axis  13  by a desired angle. 
     The transmission  18  is in the casing  20  having substantially symmetry of revolution about the axis  13  of rotation of the casing  20 . The ingredients present in the medium are thus not contaminated by the lubrication of the transmission  18 . Moreover, the transmission  18  is itself protected by the casing  20  against the intrusion of ingredients. 
     Advantageously the transmission gearings can be chosen in such a way as to operate without lubrication. For example, it is possible to choose a gear, at the end of the first shaft  14 , made from nitrided steel driving a gear on the second shaft  16  made from aluminium bronze. 
     The casing  20  having substantially a symmetry of revolution, is for example spherical. The sphere has for example a diameter of 100 mm to 500 mm. Advantageously, the casing can be droplet-shaped. The base of the casing  20  is then spherical and its connection to the transmission tube  12  is tapered. The advantage is that the connection does not have any recesses in which the ingredients of the medium can remain tapped. 
     The mixing members  22  will now be described in more detail. According to  FIG. 2 , the mixing members  22  can be open-worked vanes. This embodiment allows the mixing of non-miscible viscous ingredients such as pieces of fruit and yoghurt. According to another variant, the mixing members  22  can be solid vanes. This embodiment makes it possible to carry out an ordered mixing, i.e. an order is conferred upon the particles of ingredients in the mixture. According to yet another embodiment, the mixing members  22  can be cutters. This embodiment makes it possible to obtain a shearing effect, which is advantageous when the ingredients are powdery. The number of vanes depends on the product to be mixed and its viscosity. In particular, if it is wished to reduce the phenomenon of attrition (modification of the structure of the particles), the number of vanes is increased. 
     As  FIG. 2  shows, the shape of the mixing members  22  can be adapted to the shape of the container, so as to minimize the dead zones in the container  30 . As the members  22  are driven in rotation, they describe a circular movement. For this reason, the base of the container has a symmetry of revolution—about the first axis  13 —and its generatrix is the extreme edge of a mixing member  22 ; in the example, the base of the container is spherical and the extreme edge of the mixing members is an arc of a circle. 
     A lump breaker  26  will be described next in relation to the mixer described previously. However, the lump breaker can be used independently of the mixer as described above. In particular, the lump breaker can be used independently of the symmetry of revolution of the casing. 
       FIG. 2  shows the mixer  10  comprising the lump breaker  26  thus making it possible to carry out granulation. The lump breaker  26  makes it possible to break up the lumps of ingredients that are likely to form in the container  30 . 
     The lump breaker  26  is mobile relative to the first axis  13 , the lump breaker  26  and the mixing members  22  being on either side of a plane P ( FIG. 3 ) containing the axis  13 . 
     The arrangement of the members  22  and the lump breaker  26  on either side of the plane P prevents the two members from striking each other. Another advantage is that the ingredients are propelled by the mixing members  22  towards the lump breaker  26 , the lumps are broken up better and the granulation is achieved more rapidly. 
     The lump breaker  26  is mobile relative to the first axis  13  in such a way that the lump breaker  26  can move parallel to the axis  13  as well as in a plane perpendicular to the first axis  13 . The advantage is that the position of the lump breaker  26  can thus vary in the container  30 . The position of the lump breaker  26  can vary in height in particular in order to break up lumps which have fallen to the base of the container. 
     In order to promote granulation, a sprayer  38  ( FIG. 2 ) can be fixed on the container  30  in order to spray onto the ingredients a binding agent such as starch for example. 
       FIG. 3  shows a diagrammatic top view of the mixer of  FIG. 2 .  FIG. 3  illustrates by the various arrows possible positions which the lump breaker  26  can occupy in the plane perpendicular to the axis  13 . The lump breaker  26  can occupy any position which does not impede the rotation of the mixing members  22 . This allows a wide range of possible positions for the lump breaker  26  in the container  30 . Preferably, the lump breaker  26  is along the axis  15 . In this way, the lump breaker  26  is aligned with the casing  20  and the axis of rotation of the mixing members  22 . This arrangement is particularly advantageous as the lump breaker  26  is situated substantially in the centre of the stream of ingredients leaving the mixing members  22 . In this position the lump breaker is at its most effective. 
     According to  FIGS. 2 and 3 , the lump breaker  26  is preferably connected to the transmission tube  12 . This connection offers the advantage that the lump breaker  26  is driven in rotation simultaneously with the mixing members  22  in the movement about the axis  13  according to θ. Thus the mixing members  22  and the lump breaker  26  cannot collide, which protects them whilst ensuring a satisfactory mixing of the ingredients. Moreover, the connection between the transmission tube  12  and the lump breaker  26  allows the lump breaker  26  to be situated permanently on the other side from the members  22  relative to the axis  13  and thus to be in the stream of ingredients leaving the mixing members. Also, the connection of the lump breaker  26  to the transmission tube  12  allows the lump breaker  26  to benefit from being driven by the drive unit  32  without requiring the use of an additional drive unit. 
     The lump breaker  26  is for example connected to the transmission tube  12  by an arm  27 . The arm  27  is advantageously telescopic. Such an arm allows an easy change of position of the lump breaker  26  by deploying the arm. The arm is advantageously bent and has an substantially horizontal portion and an substantially vertical portion. The substantially horizontal portion makes it possible to displace the lump breaker  26  in the plane perpendicular to the axis  13  and the substantially vertical portion makes it possible to displace the lump breaker  26  along the axis  13 . 
     Advantageously, the lump breaker  26  can be displaced during the operation of the mixer  10 . For example, a camera makes it possible to display the inside of the container  30  and consequently to modify the position of the lump breaker  26  in the container. A control makes it possible to act on the horizontal and vertical portions of the telescopic arm  27 . 
     The lump breaker  26  makes it possible to break up the lumps of ingredients and to limit lumps in the mixture. For this purpose, the lump breaker  26  comprises vanes driven in rotation and reducing the lumps to powder. The lump breaker  26  is driven in rotation by an electric motor preferably in the telescopic arm  27 . The drive speed of the electric motor can reach for example 3000 rpm. This makes it possible to prevent transmission of the rotation movement to the lump breaker  26  via the transmission tube  12  and arm  27 . 
       FIGS. 4 to 8  are views of different embodiments of the lump breaker  26  with different cutting members. The spacing of the cutting members makes it possible to define the size of the granules. 
       FIG. 4  shows the lump breaker  26  comprising cutters  40  extending radially relative to the arm  27  and along the arm  27 . The cutters make it possible to break up the lumps and obtain a random granulation The cutters may or may not run in parallel directions. The cutters have for example two sharp edges  40   a  and  40   b  for slicing on either side of the cutters. According to the arrangement of the sharp edges in  FIG. 4 , the lump breaker  26  is driven in rotation in the trigonometric sense in such a way that the sharp edges slice the lumps. The number of cutters  40  depends on the granulation to be obtained. 
       FIG. 5  shows the lump breaker  26  comprising discs  42  superposed along the arm  27 .  FIG. 6  is a top view of a disc  42 . The discs  42  allow breaking up of the lumps and calibration of the granulation. The discs have at least one sharp edge  43 . According to the arrangement of the sharp edges in  FIG. 5 , the lump breaker  26  is driven in rotation clockwise in such a way that the sharp edge slices the lumps. The number of discs  42  and sharp-edges  43  depends on the granulation to be obtained. 
       FIG. 7  shows the lump breaker  26  comprising forks  44 .  FIG. 8  is a section A—A according to  FIG. 7 . The forks allow the lumps to be broken up. The forks also make it possible to create the phenomenon of attrition in order to round off the granules. The forks are arranged on a support  46  and are regularly spaced along the support. The support  46  is non-limitatively rectangular in  FIG. 8 . The number of forks  44  is variable and depends on the granulation to be obtained. According to  FIG. 7 , the forks extend towards the base of the container and are curved inwards towards the axis of the arm  27 . This shape makes it possible to follow to a spherical shape of the base of the container  30  and to get as close as possible to the edge of the container  30 . 
       FIGS. 9 and 10  show joints between the cap  36  and the rest of the casing  20 .  FIG. 9  shows a circular gasket  52  the lips  53  of which come to rest on the cap  36 . The gasket ensures tightness against the ingredients present in the container  30 . The gasket is for example made from PTFE resistant up to 400° C. The gasket  52  also makes it possible to confer on the junction between the cap  36  and the rest of the casing  20 , an approximate symmetry of revolution about the axis  13 , at the junction between the casing  20  and the cap  36 . 
       FIG. 10  shows another embodiment of a gasket A circular joining piece  54  is arranged on the casing  20  in such a way as to rest against the cap  36 . When the cap  36  is mounted on the casing  20 , the joining piece  54  compresses a spring  56 , for example toroidal, arranged at the base of a groove  57  of the casing  20 . Thus the joining piece  54  is pressed against the cap  36  in such a way as to promote the sealing of the casing  20  against the ingredients in the container  30 . Preferably, the joining piece  54  is pressed against a ring gasket  58  arranged on the periphery of the surface of the cap  36  in contact with the joining piece  54 . The seal is thus improved. In operation, the cap  36  is driven in rotation with the ring gasket  58  against the joining piece  54 . As an illustration, the joining piece  54  can made of steel and the ring gasket  58  can be made of elastomer. In order to improve the seal between the joining piece  54  and the casing  20 , the lips  53  of the gasket  52  can come to rest on the joining piece  54 . The gasket  52  also makes it possible to confer upon the junction between the cap  36  and the rest of the casing  20 , substantial symmetry of revolution about the axis  13 , at the junction between the casing  20  and the cap  36 . 
     In order to improve the contact between the joining piece  54  and the ring gasket  58 , the mixer  10  can comprise gasket lubricant The lubricant is for example a neutral nitrogen or argon-type gas, making it possible to prevent pollution of the ingredients in the container. In  FIG. 2 , the lubricant is injected through an orifice  60  into a conduit  62  extending along the shaft  14 . In  FIG. 10 , the lubricant enters the casing  20  into a cavity  64 . The lubricant finally reaches the contact surface between the joining piece  54  and the ring gasket  58  through a hole  66  made in a support  68  of the shaft  16 . 
     The invention also relates to an apparatus comprising the mixer  10  as described previously, comprising or not comprising the lump breaker  26 . The apparatus comprises a container  30  the base of which has a symmetry of revolution and the generatrix of which is the extreme edge of a mixing member  22 . 
     The apparatus is suitable for the rapid and efficient mixing of liquid or solid materials, for example powders. Given below are the results of mixing tests in the apparatus of the type in  FIG. 2 , without the lump breaker  26 , for a mixture of flour with puffed corn or with ascorbic acid. 
     In the first test, flour was mixed with puffed corn. These products are characterized by a considerable difference in density, making for difficult mixing. The ingredients are mixed for 30 seconds. Then, after sieving (200 μm sieve) four samples are taken and analyzed. The results of the tests are shown in Table 1. 
     
       
         
           
               
               
             
               
                   
                   
               
               
                   
                 % puffed corn 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Sample 1 
                 7.80% 
               
               
                   
                 Sample 2 
                 8.10% 
               
               
                   
                 Sample 3 
                 7.90% 
               
               
                   
                 Sample 4 
                 7.70% 
               
               
                   
                   
               
            
           
         
       
     
     This test shows a good distribution of the puffed corn. 
     In the second test, 4 g of ascorbic acid (E300) are mixed with 100 kg of flour for 30 seconds. Then, four samples of mixture are taken and analyzed in order to quantify the incorporation of the ascorbic acid into the flour (determined by the dichloroindophenol method). The test results are shown in Table 2 (g/q signifying gram/quintal). 
     
       
         
           
               
               
             
               
                   
                   
               
               
                   
                 quantity of E300 in g/100 kg of flour 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Sample 1 
                 3.72 
               
               
                   
                 Sample 2 
                 3.96 
               
               
                   
                 Sample 3 
                 4.01 
               
               
                   
                 Sample 4 
                 3.69 
               
               
                   
                   
               
            
           
         
       
     
     This test shows a good distribution of the E300 in the flour after 30 seconds&#39; mixing. 
     The apparatus comprising the mixer  10  equipped with the lump breaker  26  also makes it possible to carry out the granulation steps rapidly. 
       FIG. 11  also shows another embodiment of the apparatus; in the embodiment of the invention, the assembly comprising the mixer and its container is mounted on two concentric cradles  71  and  72 . The inner cradle supports the container  30  and the mixer  10 . The inner cradle is mounted on the outer cradle in rotation about a diameter common to the inner and outer cradles; in the figure, this diameter is perpendicular to the plane of the page. The outer cradle is mounted in rotation on a support  73 , in rotation about a diameter of the outer cradle perpendicular to the diameter on which the inner cradle is mounted. The assembly of the two cradles makes it possible to position the container  30  and the mixer  10  at any angle. The figure shows moreover an outlet  74  situated in the base of the container. 
     In the embodiment of the figure, the two cradles are concentric at a point which is the intersection of the axes  13  and  15 . Another fixed point could also be chosen for the assembly of mixers. 
     The arrangement of  FIG. 11  makes it possible to combine a rotation movement of the container and the mixer, with the movement of the mixing members. In this way, dead masses and the deposition of mixed material on the walls of the container are avoided. This makes it possible in particular to avoid the use of a scraper. 
     Of course, the present invention is not limited to the embodiments described by way of example. Thus, the lump breaker can be used irrespective of the shape of the casing. The lump breaker can be used on existing mixers.