High intensity mixer

The invention relates to a device for mixing, cooling, heating, drying and/or granulating of powder and/or granular materials, comprising a conical mixing vessel having a vertical axis, which narrows in a downward direction and in which at least one vertical mixing shaft can rotate, which mixing shaft a number of element projects, of which the outer end extends until close to the sidewall of the vessel.

From US-4,721,390 a medical mixer of very small dimensions is known for preparing under vacuum bone cement for fixing protheses at surrounding bone tissue.

The mixer comprises an agigator having a number of blades, which mixer is connectable to the feed device and a vacuum source which is connectable to the feed device for mixing substances in said feed device under

The object of the invention is the further development of this mixing device to an intensive mixer for industrial use, with which powdery, granular and/or pasty materials can be mixed, cooled, heated, dried and/or granulated.

According to the invention this object is reached with a device according to independent claim 1. Further details of the invention are defined in the dependent claims.

Other characteristics and advantages of the invention will resort from the description below of a number of embodiments, referring to the accompanying drawing.

Fig. 1 shows in partial left side view and partial right cross section a mounted mixing device according to a first embodiment with knives that carry paddles at the outer end.

Fig. 1A shows on an enlarged scale in side and front view details of Fig. 1 of the fastening of the paddles to the rods.

Fig. 2 shows in partial left side view without outer wall and partial right side view a mixing device according to a second main embodiment, of which the lid has been removed and has been hoisted upwardly over at least the length of the mixing shaft, so that the mixing shaft, the mixing elements and the bottom scraper have become free from the mixing vessel and are visible.

Fig. 2A shows on an enlarged scale in side view a detail of Fig. 2 of the pivotable connection of the knives to the mixing shaft.

Fig. 3 shows a diagram of the flow of the product in the intensive mixer according to the invention.

According to Fig. 1 the mixer is provided with a connical mixing vessel, that is generally indicated with 1, having a vertical axis 2, said vessel narrowing in a downward direction and in which at least one vertical mixing shaft 3 can rotate. From this mixing shaft 3 a number of knives 4 project gradually outwards, of which the outer end 5 extends until near the inner sidewall 6 of the vessel 1.

The vessel 1 is closed at the upper side with a lid 7, of which the innerside is substantially elipsoide shape, on the one hand for the strength and on the other hand for the inward guiding of the product part Pu that possibly moves upwardly along the inner sidewall 6 into the lid 7 and in the direction of the centre of the lid, from which it again drops back as Pd downwardly in the mixing vessel 1. Fig. 3 shows this flow diagram.

On top of the lid 7 in the axis 2 of the central mixing shaft 3 a drive motor 9 is fastened with the use of (not shown) seals and bearings on the central lid tube stub. Of this drive motor 9 the (not shown) outgoing driveshaft 10 is coupled with the mixing shaft 3. The mixing vessel 1 with the hoistable lid 7 can be closed vacuum tight by means of different types of quick fasteners, such as the screwbolt having a starhead 11 and the clamping screw 12, so that during the operation vacuum can be applied to the mixing vessel 1. After the loosening of the quick acting fasteners it is possible to hoist the lid 2 together with its accessories by means of hoist means, such as the arm 41, the double acting plunger 42, the cylinder 43 and the second arm 44 in Fig. 2. In this way the mixing knives 4 can be cleaned, exchanged or repaired. It is also possible to inspect the vessel 1 internally or the lid 7 can be removed and quickly exchanged with an other lid with accessories. At the lower end of the mixing screw 3 a scraper blade 13 is fastened in order to obviate a dead space in the bottom of the mixing vessel 1.

An excentric tube stub 14 is also mounted on the lid 7, which stub can be opened and closed by means of an inspection lid 15. This is done with a pivotable arm 16, which can be screwed with a starhead 17 on a screwbolt 18 in the closing position in a uppertaining sidelog 19 of the stub 14. On the lid 7 there is also a passage 20 for a cleaning sprayer device 21 that can be extended and retracted, which spraying device carries a spray head 22 inside the vessel 1. At the lower side of the mixing vessel 1 a flange 23 is fastened, on which the body is mounted of a ball segment valve 24, which contains a ball segment 25.

At the left half of Fig. 1 is shown, that the mixing vessel 1 is provided with an outer jacket 26 for heating and for cooling of the contents of a product P of the vessel 1. This jacket 26 carries the connecting tube stumps 28 and 29.

It is also possible, such as shown in the right half of Fig. 1, that the sidewall 6 is made of a so-called "template", which is a double walled plate 13 that has been connected by welding in different places and is afterwards expended. Through the created hollow space again a cooling or heating medium can be circulated. The lid 7 comprises a tube stub 32 for a looking glass 33.

According to the invention the mixing shaft 3 carries a great number of knives 4 and has a high to very high number of revolutions N. In this way the product to be treated experiences a very strong shearing at both the knives 4 as the inner sidewall 6, so that in a very short time a very intensive mixing of the product P is effected. By this mixing action a temperature rise can occur, which is counteracted by cooling the sidewall 6 of the mixing vessel 1.

According to a main embodiment of the invention the number of revolutions N of the mixing vessel comprises 100 tot 1000 revolutions per minute.

At a first preferential embodiment of the invention the knives 4 each carry at the outer end one or more mixing paddles 5, of which an outer edge extends parallel to and near the inner sidewall 6 of the vessel 1. Furthermore, the knives 4 are rod shaped and have a large radial dimension. Furthermore, the paddles 5 are plate shaped and have a small radial dimension. According to Fig. 1A at the left side of Fig. 1 the paddles 5 are limited pivotable over an angle (A) round the longitudinal axis of the rod shaped element.

In Fig. 2 a second preferential embodiment of the invention is shown in the hoisted position of the lid 7 with accessories. The lid 7 is suspended on the upwardly and downwardly moveable horizontal arm 41 on the head of a hydraulic plunger 42 of a hoisting cylinder 43 which carries a fixed horizontal arm 44 at the upperside, on which the mixing vessel 1 is suspended. Also other that hydraulic hoisting tools can be applied.

Here the knives 4 according to the invention comprise knives, of which the angle B with the vertical of at least a part of the knives is variable.

At a variant drawn at the right side of Fig. 2 the mixing shaft 3 and the knives 4 that are connected therewith are hollow and have outlet holes 45 for letting through and guiding of gasses and/or liquids U. In Fig. 2A also a detail of the pivotable connection of the knives 4 with the mixing shaft 3 is shown. Here the scraper 13 at the lower end of the mixing shaft 3 is visible.

At the variant shown at the left side of Fig. 2 the angle B is variable which the knives 4 make with the vertical. Furthermore, the outer sidewall 6 of the mixing vessel 1 is bound with a 1/2 tube spiral 46 for passing through a cooling and/or heating fluid. The lid 7 is provided with a tube stub 36 for the entrance of the product Pi. At the lower end of the mixing vessel 1 a flat outlet slide 47 with an operating lever 48 for the outgoing product PO is mounted.

At the upperside of the mixing vessel 1 the mixing shaft 3 is accoupled by means of a transmission 49 with the inverted suspended drive motor 9, which transmission is fastened on the lid 7 by means of a heightened tube stub 8. In the axis 2 an inlet 50 for liquid Li is mounted. The lid 7 is also provided with a port 38 for a low pressure sprayer 39 for process liquid and/or gas.

The sidewall 6 of the mixing vessel 1 is provided at the right side with a port 34 for a thermometer 35.