Van den Brink et al. (54) MIXERAPPARATUS AND METHOD FOR SANTARY MEXING OF SOLDS WITH OTHER SOLIDS AND/OR LIQUIDS 75 Inventors: Gilbert J. J. Van den Brink, Cranbury, N.J.; Koos Leemker, Lelystad, Netherlands 73 Assignee: Schugi, Lelystad, Netherlands 21 Appl. No.: 47,747 22 Filed:
May 8, 1987
4,767,217 Aug. 30, 1988
A method and apparatus for mixing two substances under sanitary conditions in which a solid particulate substance is introduced into an inlet chamber with ra
dial and downward velocity components and is mixed with a second substance in a mixing chamber below the inlet chamber by rotating a vertical shaft with mixing blades thereon in the mixing chamber. The mixing chamber is formed with a flexible wall which is de
51) Int. Cl.".......................... B01F15/02; B01F 5/04 52 U.S. C. ..................................... 366/168; 366/219 58) Field of Search ............... 366/167, 168, 172, 173,
formed as the shaft rotates to prevent accumulation of mixed product on the wall. The vertical shaft is rotat ably supported by bearings outside the inlet and mixing chambers so as not to contaminate the substances being
tions and the mixture of substances is discharged from below the mixing chamber. When the second substance
4,453,832 6/1984 Schumacher ....................... 366/167
Primary Examiner-Robert W. Jenkins Attorney, Agent, or Firm-Roberts, Spiecens & Cohen
mixed so that mixing takes place under sanitary condi
is a liquid, the mixed product is an agglomeration of particles, a paste, a slurry or a solution. The bearings are mounted in a bearing assembly outside the inlet and mixing chambers and a motor is connected to the bear ing assembly so as to be removed with it, as a unit, together with the vertical shaft and blades and a portion
of the inlet chamber.
34 Claims, 4 Drawing Sheets
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U.S. Patent Aug. 30, 1988
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MIXER APPARATUS AND METHOD FOR SANTARY MXNG OF SOLIDS WITH OTHER
SOLIDS AND/OR LIQUIDS FIELD OF THE INVENTION
Moreover, the conventional mixer is intended to op
The invention relates to a mixer for mixing solids
with other solids and/or liquids under sanitary condi tions and to the method of such mixing. BACKGROUND
pharmaceutical and allied industries, there is the addi tional problem of bacteria growth at places which con tain remnants of product. These two problems cannot sufficiently be solved by cleaning the mixer without disassembly.
There are many circumstances under which it is nec
erate continuously. This has the advantage over batch mixers in that it can produce large output more eco nomically with less labor and the products are more uniform. However, if frequent changes are necessary for different product formulations, different dyes, dif ferent liquid binders and the like, the existing continu ous mixer is disadvantageous as compared to batch
essary to effect mixing of solids with liquids and/or solids under absolutely sanitary conditions. These in clude the production of food products, pharmaceutical 15 mixers as the latter can be cleaned more quickly. Batch products, mineral products and chemical products of mixers are usually trough-shaped ribbon blenders or paddle mixers, conical mixers, fluid bed granulators, high purity. The products of the mixing can be in the form of and the like. These are all easily accessible and clean mixed powders, wet granules, pastes or slurries. able. The more troublesome cleanability of the conven In the production of the mixed products, it is essential 20 tional mixers as disclosed in U.S. Pat. No. 3,887,166 that the products do not come into contact with con causes extra down time between changeover of prod taminants, such as bearing lubricants. It is also essential uctS. that the mixing apparatus be easily cleaned to prevent In the food industry, the known mixers are used to contamination of the product with any built-up product transform powdery products into agglomerated prod which remains within the mixing apparatus. The appa 25 ucts in order to instantize these products. Powdery food ratus should also be of a construction to preclude such products, such as a cake or pudding mix, a sauce mix, build-up of product. have a tendency to float on top of the liquids which The mixing apparatus and method of the invention is etc. are added to them, while subsequent stirring often leads directed to the mixing of solids with other solids and/or to the forming lumps. After stirring vigorously for a liquids and is distinguished from liquid-liquid mixers. In 30 while, the totalofproduct, including some or most of the this regard, the mixing of solids with other solids and/or will disperse in the liquid (usually water or milk). liquids is effected at high speeds of rotation, between lumps, 1000 and 4000 rpm, of a mixing shaft in a mixing cham In contrast, agglomerated products usually have good ber. This produces high shear forces and is contrasted wettability, sinkability and dispersion speed in the liq with a liquid-liquid mixer in which the speed of rotation 35 uids in which they have to be reconstituted. These char is much lower and relatively low shear forces are devel acteristics make the agglomerated products instant. In the pharmaceutical industry, the known mixers are oped. Furthermore, because of vessel size, the shaft in the liquid-liquid mixers is able to deflect or tilt consider used to transform powdered pharmaceutical com ably without any adverse effect. In contrast, the mixing pounds into free flowing masses prior to being fed into of solids with other solids and/or liquids is effected in a fast operating tableting machines. Powdery compounds mixing chamber which has close tolerance with the have poor flow properties and cannot be fed quickly shaft and permissable deflection or tilt of the shaft is and evenly into the small molds of a tableting machine minimal. Rotating shafts have a critical speed at which which compresses the product into a tablet. The in the shaft undergoes maximum deflection or tilt. The crease in speed of current tableting machines necessi
critical speed is a function of a number of factors, such 45 tates even greater free flowing properties of the phar as rigidity of the shaft, diameter and length of the shaft, maceutical compounds. Moreover, agglomerated prod type of support of the shaft etc. When the shaft of a ucts have better compressibility characteristics than mixer goes from rest to its operating speed during start powdery products. up and in reverse during stoppage, the shaft passes In the chemical industry, special alloys in powdery through its critical speed. In liquid-liquid mixers, this is 50 form have to be agglomerated order to end up with a of little significance and the critical speed may even be free-flowing granular productinwhich the molds within the operating speed of the mixing shaft. In mixers quickly and completely in which specialfills parts, such as of solids with other solids and/or liquids, the critical tools, are fabricated by sintering. No contaminants speed of the mixing shaft and the maximum deflection should be present in the sintering stage. become important factors. 55 In the case of pesticides, one plant should be able to U.S. Pat. No. 3,887,166 discloses a mixer for mixing solids with liquids in which the wall of the mixing produce, for example, broad-leaf and narrow-leaf herbi cides. Obviously, cross contamination would create a chamber is made of flexible material and the wall is constantly deformed during mixing to prevent build-up herbicide which would destroy everything. Since there of deposits on the wall. are formulations where only a few grams per acre of
Although this mixer has proved to be of substantial value in continuously producing products under rela tively controlled conditions, there is still a need for a mixer for producing highly pure products which meet stringent sanitary requirements. Namely, in this mixer unavoidable remnants of product are left behind in dead corners, in cracks and in crevices, which will contami nate the next load of product. Moreover, in the food,
active matter are needed to obtain the desired effect, cross-contamination must be avoided. 65
The ceramic industry has applications where frequent color changes are necessary, for example, when produc ing all types of mosaic tiles. To ensure perfect color consistency of all batches of tiles, no matter when man ufactured, it is imperative that there be no cross-con tamination of dyes.
4. the invention, the method comprises supplying a solid, particulate substance into an inlet chamber with radial and downward velocity components, mixing a second substance, such as a liquid, for example, water, a slurry,
3 The above represent only a few of the multitude of
applications where easy-cleaning and thorough clean ing of the agglomerator is of utmost importance. In general, in order to effect mixing or agglomera tion, the following conditions must be maintained.
packing. No cracks or dead corners. Internal radii in corners. Welded connections instead of bolted ones.
Easy assembly and disassembly for manual cleaning. SUMMARY OF THE INVENTION
An object of the invention is to provide a mixer in which solids can be mixed with solids and/or liquids 15 under sanitary conditions suitable for producing food products, pharmaceuticals, minerals, and chemical products of high purity. A further object of the invention is to provide such a mixer which is so constructed to prevent build-up of 20 product therein. Another object of the invention is to provide such a mixer which is easily and rapidly dismounted to permit replacement of parts and cleaning of the interior of the mixer.
In order to satisfy the above and further objects of the invention, there is contemplated a mixer for effecting mixing under sanitary conditions comprising a mixing chamber, a rotatable mixing shaft in said mixing cham ber, said shaft extending vertically, blade means on said 30 mixing shaft for mixing a product in the mixing cham ber, an inlet chamber secured to said mixing chamber and including a first inlet means for introducing solid particles into the inlet chamber, and a second inlet means for combining a second substance with the solid 35 particles. The mixing shaft projects vertically above and outside said inlet chamber and a bearing assembly is secured above and outside said inlet chamber to rotat ably support the mixing shaft. The bearing assembly includes first and second bearings located one above the other each rotatably supporting said shaft. The shaft extends downwardly in suspended manner from said bearing assembly and freely projects without any other support into the inlet and mixing chambers. A seal means is located outside said inlet chamber for sealing 45 said shaft and said inlet chamber. The mixing chamber comprises a tubular wall of flexible material surround ing said blade means and the wall is deformed as said mixing shaft rotates to prevent accumulation of mixed material on said wall. The wall has a bottom outlet for
discharge of the mixed material. According to one preferred embodiment, the second substance is a liquid and the injector means injects the liquid onto the powder substance to wet the particles. A feature of the invention is that the inlet chamber is made in two parts constituted by separable upper and lower portions, the lower portion being secured to the mixing chamber and containing the injector means, while the upper portion incorporates the inlet means for the solid particles. A further feature of the invention is that the bearing assembly, the mixing shaft and the upper portion of the inlet chamber can be removed as a unit to provide ac cess to the interior of the mixing chamber and/or to replace the mixing shaft and/or the bearing assembly. Another object of the invention is to provide a method for mixing solids with other solids and/or liq uids under sanitary conditions and in accordance with
a paste, solution, etc. with the particulate substance in a
mixing chamber below the inlet chamber by rotating a vertical shaft with mixing blades thereon in said mixing
No metal to metal connections without intermediate
chamber, deforming the mixing chamber as the shaft rotates to prevent accumulation of mixed products in the mixing chamber, rotatably supporting the vertical shaft by bearings outside the inlet and mixing chambers so as not to contaminate the mixture whereby sanitary mixing takes place and discharging the mixture from below the mixing chamber. BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING
FIG. 1A is a diagrammatic elevational view, partly broken away in section, of the upper portion of a mixer according to the invention. FIG. 1B shows the lower portion of the mixer, the reference characters L1-L6 in FIGS. 1A and 1B show ing the connection points of the elements of the Figures. FIG. 2 is an elevational view taken at 90 from the
view in FIGS. 1A and 1B showing the entire mixer on a smaller scale. FIG. 3 is a sectional view taken on line 3-3 in FIG. 1A.
FIG. 4 is a sectional view taken on line 4-4 in FIG. 1B.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to the drawing, next will be described a sanitary mixer, generally designated M in which solid particles, for example, in powder form are wetted by a liquid and the wetted particles are mixed to produce an agglomeration thereof. The agglomerates are dis charged from the mixer and then dried, optionally after completion of a chemical reaction, to obtain a free flow ing granular product. If the liquid is supplied in greater amount, the end product discharged from the mixer will be a paste, slurry or solution depending upon the amount of liquid
which is supplied. The mixer M is specially constructed in order to produce pure products under sanitary conditions. Although the mixer will be described hereafter for addition of a liquid to wet powder solids and mix the same, the mixer can also be utilized for producing a mixture of dry solids, for example, in powder form.
The mixer M comprises a frame 1 intended to be supported on a rigid, solid base or foundation. The frame 1 supports a mixing chamber 2 above which an inlet chamber 3 is supported in axial alignment. The mixing chamber 2 comprises a tubular wall 4 of flexible material, such as rubber. An upper edge portion 5 of the tubular wall is engaged in a recess 6 in a clamping ring
60 7 which is secured to the frame 1. The lower end of the
tubular wall 4 has a conically flared skirt portion 8, which is clamped by a clamping ring 9 to the frame 1. Because the tubular wall is secured at its upper and lower edges, it can be placed under tension. The inlet chamber 3 comprises an upper portion 10 and a lower portion 11 which are detachably connected together by bolts 12. The lower portion 11 is welded to the frame 1.
4,767,217 5 6 The upper portion 10 of the mixing chamber has two shaft 20. The mixing shaft is supported by bearings 33 tubular inlets 13 arranged in diametric opposition to one and 34 which are vertically spaced and provide for another. The tubular inlets 13 are inclined upwardly rotational support of the mixing shaft 20 in the bearing and outwardly at an acute angle of about 45 with re assembly 25. The bearings 33 and 34 are sealed bearings spect to a vertical axis x-x of the mixer. The tubular of permanent lubrication. Normally, the bearings 33 and inlets 13 each serve for introduction of a solid, particu 34 will be sufficient to support the weight and axial late material, for example, a powder into the mixing thrust of the shaft and the blades, however, if the load
chamber 3. Each inlet 13 is capable of introducing a respective particulate material or mixture thereof, and the materials which are introduced into the two inlets may be different or the same. Although two inlets 13 are shown, it will be evident that a greater number can be employed on the upper inlet portion 10, preferably in a symmetrical annular arrangement around the vertical
becomes too great, the coupling 32 can be supported by
a thrust bearing 35, also sealed and of permanent lubri Because the mixing shaft 20 is supported in bearings 33, 34 outside the inlet and mixing chambers, the latter chambers are isolated from any potential contamination by lubricant from the bearings. The mixing shaft 20 is axis of the mixer. Furthermore, because the upper por 15 effectively suspended from its drive means composed of tion 10 is detachable from the lower inlet portion 11, a the drive motor 29 and the bearing assembly 25 so as to replacement inlet portion can be re-attached with a be freely suspended within the inlet and mixing cham greater or lesser number of inlets 13. bers. The mixing shaft 20 freely projects without any The upper portion 10 is of generally dome-like con other support into the inlet and mixing chambers. figuration, which may be conical or spherical in shape, 20 The bearing assembly 25 is interposed into a space and it is provided with a flat upper wall 14 between the defined above the flat wall 14 of the mixing chamber inlets 13. and within the confines of the inlets 13. This provides The lower portion 11 of the inlet chamber comprises for a compact assembly and minimizes the overall a conical wall 15 which tapers inwardly at substantially length of the mixing shaft 20. the same angle as the inlet portions 13 and which is 25 The mixing shaft 20 operates at relatively high speeds joined to a cylindrical wall 16 whose lower end is in order to achieve mixing of the solids and their wet welded to the frame 1 and is coaxial with tubular wall 4. ting by the liquid. The agglomerated particles produce A plurality of inlets 17 are incorporated in the tubular a substantial stress on the mixing shaft 20 due to their wall 16 for detachably receiving a liquid injector 18. resistance and unbalance which is considerably greater The injector 18 projects downwardly into the interior 30 than for liquid mixers which operate at relatively low of the mixing chamber 2. The liquid injector 18 faces speed. The stress which is produced on the mixing shaft downwardly and is adapted to inject liquid onto the of liquid mixers is relatively insignificant. solid particles which have been introduced into the inlet The blade assemblies 21, 22 and 23 have radially chamber 3 at the inlets 13 in order to wet the particles projecting blades 36 to achieve mixing of the wet parti so that they will undergo mixing and agglomeration in 35 cles to effect agglomeration thereof. The tips of the the mixing chamber 2. blades 36 are spaced from the inner surface of the flexi The arrangement of the conical chamber in portion ble wall 4 by a distance of 5 to 10 mm. The mixing shaft 11 in axial continuation of the dome-like chamber in 20 must rotate with accuracy on its vertical axis of portion 10 thereabove is very effective in the smooth rotation in order to maintain the clearance of the tips of and controlled introduction of solids into the mixing the blades 36 with the flexible wall and prevent cutting chamber without turbulence which leads to the produc of the wall by the blades 36. Because of the vertical tion of mixtures of solids which are homogeneous and suspension of the shaft freely in the inlet and mixing uniform. There is virtually no dead space above the chambers and the support of the shaft outside the cham inlets 13 within the inlet chamber which results in high bers by the vertically spaced bearings without further efficiency and mixing under controlled conditions 45 the shaft is made relatively rigid to assure its whereby a uniform granulate product is discharged support, clearance with the flexible wall during high speed rota from the mixer. tion. The operational rotation speed is between 1000 A vertical mixing shaft 20 extends through the inlet and 4000 rpm. It has been surprisingly found that the chamber 3 into the mixing chamber 2 and carries blade critical speed of the shaft at which it undergoes maxi assemblies 21, 22, and 23 for achieving mixing of the 50 mum deflection is below the operation speed of 1000 to wet particles to obtain agglomeration thereof. 4000 rpm. This minimizes the wear on the bearings as The shaft 20 exits through an opening 24 in the flat the critical speed is only attained momentarily when the wall 14 of the inlet chamber and is supported outside the mixing shaft is being brought up to speed or is undergo inlet chamber 3 in a bearing assembly 25 which is de ing stoppage. In order to vary the speed of the shaft tachably connected by bolts 26 to an upward extension 55 according to the mixing operation to be effected, the 27 of the upper portion 10 of the inlet chamber 3. The drive motor 29 is frequency controlled in order to per upward extension 27 is composed of a plurality of angu mit continuous control of the mixing speed. lar segments 28 which extend in spaced relation around order to seal the shaft 20 where it exits through the the bearing assembly 25. Thereby, the external surfaces flatInwall at opening 24, a seal 37 is interposed be of the bearing assembly and the upper portion 10 of the tween the14bearing assembly 25 and the flat wall 14. The inlet chamber are accessible for cleaning purposes. seal 37 comprises a pair of spaced rings 38 which sup A drive motor 29 is detachably connected by fasten respective seal members 39 and 40 at upper and ers 30 to the bearing assembly 25 in axial alignment port lower ends. The seal members 39 and 40 each abut therewith. against a respective ring 38. Seal 39 comprises a tubular A drive shaft 31 of the drive motor 29 is secured in a 65 lip 41 which engages the underside of the housing of the coupling 32, and the mixing shaft 20 is also secured in bearing assembly 25, while seal 40 has a tubular lip 42 the coupling 32. In this way, there is a drive connection which engages the upper surface of the wall 14. The between the drive shaft 31 of the motor and the mixing distance between the rings 38 is adjustable so that the 10 cation.
7 lips 41 and 42 resiliently abut against their respective bearing surfaces and also bear resiliently in sealing fash
ion against the outer surface of the mixing shaft 20. This
construction of the seal 37 not only seals the wall 14 of the mixing chamber but also ensures that there will be no contamination of lubricant from the bearings into the
inlet chamber 3.
Since the mixer is intended to achieve mixing of solids with other solids and/or liquids under sanitary
conditions for the production of food, chemicals, miner als or pharmaceutical products of high purity, it be comes necessary to clean the interior of the mixer from time to time. In order to effect so called "cleaning in place' of the mixer, a cleaning head 43 can be introduced into the inlets 13 for injecting a cleaning fluid under high pres
sure into the interior of the inlet chamber 3. The clean
ing head 43 includes a spherical ejector with a number of holes therein for the discharge of the cleaning fluid. The cleaning head 43 can be pivoted and moved axially 20 within the mixing chamber 3 in order to flush all regions thereof with the cleaning fluid. The smooth dome-shape of the interior of the upper portion 10 of the inlet cham ber and the merged conical lower portion 11 of the inlet 25 chamber insures that the cleaning fluid will thoroughly wash the interior of the inlet chamber and no re-entrant corners or crevices are formed in which residues could be retained.
8 In order to prevent accumulation of agglomerated material on the flexible wall 4, a deforming means 50 is mounted outside the wall 4 to continually deform the wall 4 during mixing. The deforming means 50 com prises a plurality of cylindrical rollers 51 which are arranged around the wall and bear against the external surface of the wall to deform the same. The rollers 51 are rotatably supported by tapered bars 52 secured to a cage 53 which undergoes intermittent movement in the form of vertical reciprocation concurrently with rota tion of the mixing shaft 20. In order to achieve the vertical reciprocation of the cage 53, pneumatic cylin ders 54 are arranged in diametric opposition on frame 1 and are connected by pivot joints 55 to rigid arms 56 connected to cylinders 57 which are slidable on fixed shafts 58 supported by frame 1. The pneumatic cylin ders 54 undergo pulsed actuation as the shaft 20 rotates to cause the arms 56 to be shifted vertically and produce vertical reciprocation of cylinders 57 on shafts 58 which results in vertical reciprocation of the cage 53 and the rollers 5i on the tubular wall 4. This reciprocatory movement of the cage 53 causes the wall to undergo continual deformation under the bearing of the rollers 51 against the outer surface of the wall. Because the rollers 51 bear against the wall to deform the same, the wall undergoes slight vertical stretching as the cage reciprocates vertically. Because the wall is under ten sion due to its secured states at its upper and lower edges, the vertical stretching is slight. Although the pneumatic cylinders 54 and the shafts 58 have been shown fixed to the frame, it is possible to provide a rotatable support for the cage and to rotate the cage around the wall to produce the deformation thereof,
In order to achieve more extensive cleaning of the 30 interior of the inlet and mixing chambers, the construc tion makes it possible to remove the upper portion 10 of the mixing chamber, the bearing assembly 25, and the motor 29 as a unit from the lower portion 11 after de taching the bolts 12. When the unit is removed from the 35 The blade blocks 21, 22 and 23 are fixed to a collar 60 lower portion 11 of the inlet chamber, the mixing shaft which is secured to the mixing shaft 20. The blades 36 20 will be withdrawn therewith. In general, after the are welded to the respective blocks 21, 22 and 23. The bolts 12 are detached, the entire unit is hoisted verti blocks 21, 22 and 23 are detachably connected to the cally so that the shaft 20 can be axially removed from collar 60. The collar 60, in turn, is detachably connected the mixing chamber and the inlet chamber. When the 40 to the shaft 20 by an end ring 61 which is welded to the unit has been removed, there will be access to the inte collar and held in place on the shaft by a bolt 62 threaded into an end of the mixing shaft 20. rior of the inlet chamber 3 and the mixing chamber 2. As previously noted, the flexible wall 4 is secured at In the event that there should be a breakage of any of the blades 36 of the blade assembly 21-23, or a fracture its upper and lower ends and this minimizes surging of of the mixing shaft 20, the aforesaid unit can be quickly 45 the product discharged at the lower end of the mixing chamber. In conventional equipment, the lower end of removed and replaced with another unit. the flexible wall is unsecured and this leads to axial The aforesaid unit can also be removed when the products to be mixed in the mixer are to be changed. displacement of the flexible wall 4 which produces the surging at the outlet. The conical widening arrange Removal of the unit enables the interior of the inlet and mixing chambers to be cleaned and the unit can be 50 ment of the skirt 8 precludes build-up of material on the replaced by a clean unit. Consequently, there is little wall 4 and facilitates discharge by gravitational forces. possibility of cross contamination of the different prod Additionally, by mounting the lower end of the skirt 8 ucts in the successive mixing operations. The removed between the clamping ring 9 and the frame 1 a seal is unit can be cleaned outside the mixer for future opera formed at the outlet of the mixing chamber which pre tions. It is of significance to note that the liquid injector 55 vents any intrusion of contaminants. The mixer M can be operated as a continuous treat 18 is removed before the unit is vertically hoisted out of place, and that the inlets 17 remain in place on wall 16 ment mixer and it can periodically be cleaned routinely. of the lower portion 11 of the mixing chamber 3 during When the mixer is to be changed over to produce a the removal of the unit. In general, it is to be seen that different product, the motor 29, bearing assembly 25, the liquid inlets 17 do not interfere with the placement 60 and upper portion 10 of the inlet chamber are removed or removal of the upper portion 11 with its solids inlets as a unit together with the mixing shaft 20 and cleaned 13. or replaced while the interior of the remaining inlet In the assembled state, the liquid injector 18 is located chamber and mixing chamber is cleaned. This change relatively far below the inlets 13 so that there is little over is relatively quick and minimizes down time of the opportunity for the liquid to atomize and flow up above 65 mixer. A number of features of the mixer M which satisfy the solids where contamination could take place. Addi tionally, the dome-like shape of the upper portion 10 the objects of the invention are noted particularly here after. affords no space in which the liquid can build up.
9 The frame 1 including the lower portion 11 of the inlet chamber is a one-piece unit of a welded construc
10 said wall having a bottom outlet for discharge of mixed
No sharp corners are formed in the inlet and mixing
inlet means comprises a liquid injector, the second sub stance being a liquid. 3. A mixer as claimed in claim 2 wherein said liquid
chambers where product can be trapped. The liquid injector 18 is connected in the mixer by a
material. 2. A mixer as claimed in claim 1 wherein said second
quick-release coupling at inlet 17. injector is positioned to inject the liquid into said mixing The inlets 13 are inclined downwardly and inwardly chamber. towards axis x-x at substantially the same angle as the 4. A mixer as claimed in claim 3 wherein said liquid conical wall 15 of the lower portion 11 which in combi 10 injector is disposed in said mixing chamber above said nation with flat wall 14 produces smooth inlet flow of blade means. 5. A mixer as claimed in claim 1 comprising a thrust powder solids with radial and downward velocity com ponents without any dead space in the inlet chamber bearing for said shaft in said bearing assembly. above the openings for the solids inlets 13 and no dead 15 6. A mixer as claimed in claim 1 wherein said tubular Corners. wall has upper and lower ends which are fixedly se The bearing assembly 25 is disposed entirely outside cured, said bottom outlet being at said lower end. 7. A mixer as claimed in claim 6 wherein said lower the inlet and mixing chambers. The bearings are sealed and permanently lubricated. end of the tubular wall tapers in conically widening The shaft 20 is freely suspended in the inlet and mix fashion and terminates at said bottom outlet. ing chambers and has an increased length compared to 20 8. A mixer as claimed in claim wherein said inlet conventional mixers which makes it possible to position chamber comprises upper and lower portions, the lower the liquid injector in the mixing chamber 2 well below portion being secured to the mixing chamber, said first the inlets 13. This enables the injection of liquid in a inlet means being in said upper portion. spray onto a curtain of falling powder which produces 25 9. A mixer as claimed in claim 8 wherein said lower portion has a conically flared head section and a tubular uniform wetting and mixing. base section coincident with said mixing chamber. The shaft is directly driven by the motor 29. 10. A mixer as claimed in claim 9 wherein said first The motor 29 can be regulated in its drive speed. means comprises at least two inlet portions extend The blade blocks 21, 22, 23 are not separately inlet mounted on the shaft 20 but are all mounted on the 30 ing at an angle to the vertical shaft. 11. A mixer as claimed in claim 10 wherein said angle common collar or sleeve 60. is an acute angle. The blades 36 are welded to the blade blocks 21-23 or 12. A mixer as claimed in claim 10 wherein the angle collar 60. of the inlet portions relative to the vertical shaft is the The wall 4 is secured at its opposite ends. same as the angle of the conically flared head section of The rollers 51 are mounted by the tapered bars 52 on 35 the lower portion relative thereto. cage 53 in a distributed array around the wall 4. 13. A mixer as claimed in claim 8 wherein said second This leads to less vertical stretching of the wall 4 and inlet means has an inlet disposed in said lower portion of minimal surging of the discharged product whereby the the inlet chamber. product is homogeneous, and more uniformly agglom 14. A mixer as claimed in claim 8 comprising means erated. said bearing assembly to said upper portion of Although the invention has been described in relation securing the inlet in fixed relation thereto, and means to a specific embodiment thereof, it will become appare detachablychamber connecting the upper and lower portions of ent to those skilled in the art that numerous modifica the inlet chamber so that the bearing assembly, the tions and variations can be made within the scope and upper portion of the inlet chamber said mixing shaft spirit of the invention as defined in the attached claims. 45 can be removed as a unit from the and lower portion of the What is claimed is: chamber and said mixing chamber and provide 1. A mixer for mixing substances under sanitary con inlet access to the interior of the inlet chamber and the mix ditions comprising a mixing chamber, a rotatable mixing shaft in said mixing chamber, said shaft extending verti ing15.chamber. mixer as claimed in claim 14 comprising drive cally, blade means on said mixing shaft for mixing a 50 meansAdisposed the bearing assembly for driving product in said mixing chamber, an inlet chamber se said mixing shaft,above said drive means being secured to said cured to said mixing chamber and including first inlet bearing assembly for removal with said unit. means for introducing solid particles into the inlet 16. A mixer as claimed in claim 1 comprising drive chamber, second inlet means for combining a second means disposed above the bearing assembly and coaxi substance with the solid particles which have been in 55 ally arranged in driving relation with said shaft. troduced in the mixing chamber, said mixing shaft ex 17. A mixer as claimed in claim 16 wherein said drive tending vertically outside and above said inlet chamber, means is frequency controlled for continously control a bearing assembly secured outside and above said inlet ling the mixing. chamber and including first and second bearings located 18. A mixer as claimed in claim 16 wherein said drive one above the other rotatably supporting said shaft, said means is secured to said bearing assembly as a unit. shaft extending downwardly in suspended manner from 19. A mixer as claimed in claim 1 comprising means said bearing assembly and freely projecting without any securing the bearing assembly to the inlet chamber in other support into the inlet and mixing chambers, and fixed relation thereto. seal means for sealing said shaft and said inlet chamber, 20. A mixer as claimed in claim 1 wherein said means said mixing chamber comprising a tubular wall of flexi 65 for deforming said wall as said shaft rotates comprises ble material surrounding said blade means, and means cylindrical rollers engaging said tubular wall on the for deforming said wall as said mixing shaft rotates to outer surface thereof and disposed around said wall to prevent accumulation of mixed material on said wall, deform the same.
21. A mixer as claimed in claim 1 wherein said means
for deforming said wall as said shaft rotates comprises cylindrical members bearing against said wall and rotat able thereon.
22. A mixer as claimed in claim 1 wherein said means
for deforming said wall as said shaft rotates comprises bars. 23. A mixer as claimed in claim i wherein said means
for deforming said wall as said shaft rotates comprises deforming members bearing against said wall and means for intermittently moving said deforming members.
24. A mixer as claimed in claim wherein said means
for deforming said wall as said shaft rotates comprises
means for vertically stretching said wall intermittently
12 an inlet chamber with radial and downward velocity components, mixing a second substance with the partic ulate substance in a mixing chamber below the inlet chamber by rotating a vertical shaft with mixing blades thereon in said mixing chamber, deforming the mixing chamber as the shaft rotates to prevent accumulation of mixed product in the mixing chamber, rotatably sup porting the vertical shaft by bearings outside the inlet and mixing chambers so as not to contaminate the sub stances whereby mixing takes place under sanitary con ditions and discharging the mixture of substances from below the mixing chamber. 30. A method as claimed in claim 29 comprising sus pending the vertical shaft from the bearings outside the inlet and mixing chambers and sealing the shaft where
15 as the shaft rotates. the shaft enters the inlet chamber. 25. A mixer as claimed in claim 1 wherein said means 31. A method as claimed in claim 29 wherein said for deforming said wall is rotatable around said wall as second substance is a solid. said shaft rotates. 32. A method as claimed in claim 29 wherein said 26. A mixer as claimed in claim 1 wherein said blade
means comprises a plurality of blade blocks on said shaft superposed above one another, and blades being se
cured to said blade blocks. 27. A mixer as claimed in claim 26 wherein said blades are welded to said blade blocks. 28. A mixer as claimed in claim 26 wherein said blade 25
means further comprises a removable sleeve secured to said shaft, said blade blocks being secured to said sleeve. 29. A method of mixing two substances to produce a mixed product under sanitary conditions, said method comprising supplying a solid particulate substance into
second substance is a liquid, said liquid being injected onto the powder substance as the powder substance travels downwardly. 33. A method as claimed in claim 29 comprising re moving as a unit from said mixing chamber, said shaft, said bearings and a portion of said inlet chamber and replacing said unit with a cleaned unit. 34. A method as claimed in claim 33 wherein said unit is removed from the mixing chamber by vertically hoisting the unit out 8 of:the Xmixing chamber. & X