Interesting questions and answers about the Gyraton® mixer
If a bulk material batch (powdery, dusty, granular, flaky, flaky, fibrous, dry, moist, good or bad flowing) is to be homogeneous, the mixing process is carried out with precision mixers. However, typical precision mixers are not suitable for cost reasons if the bulk material batch is e.g. 10 m³, 40 m³ or 80 m³. Gyraton® mixers can ideally solve exactly these tasks.
What prompted amixon® to develop another powder mixer?
- Low electrical connected load: Gyraton® mixers work particularly effectively with low motor power and homogenize your mixing materials particularly gently.
- Lower construction costs: Very low space requirement due to compact design. Large-capacity mixers are usually located within the building envelope Other large mixers have an upright conical mixing chamber. Such large cone mixers also have good mixing properties, but they require approximately three times the building height. It is expensive to build a production hall of this height.
- Less stress for your bulk goods: In addition, it is expensive in the long run if the mixed materials have to be conveyed three times higher into the mixing chamber (large vertical conveyor and permanently higher operating costs, possibly undesirable particle size reduction).
- Quick installation and commissioning: Gyraton® mixers are designed so that they can be transported lying down on a low-loader. They are delivered fully assembled. The height of the low-loader including the load is usually less than 4 metres. This allows motorway bridges in Europe to be passed without any problems.
- Easy inspection and cleaning: Gyraton® mixers have large inspection doors. They can be easily inspected and cleaned. The Gyraton® mixers can be walked on and cleaned wet or dry.
It is well known that the spirals of the amixon® vertical single-shaft mixer rotate slowly. What is the difference to the Gyraton® mixer?
Of course, you can build existing precision mixers correspondingly large and use them as high-capacity mixers. It would not matter whether they work with a horizontal or vertical mixing shaft. But that would be very expensive: on the one hand because of the expensive components gearbox and motor. On the other hand, because of the high electrical power of several hundred kW. Such a large mixer would only need a few minutes of mixing time for homogenisation. However, this is not necessary in operational practice. Longer periods are usually available for large-volume homogenisation tasks. These can be chosen by the customer. It can be a fraction of an hour. But it can also be several hours. The longer the time, the smaller the motor.
In this respect, there are not many mixer designs that can be used economically and effectively for homogenizing large batches (more than 10 or 80 m³), especially if they are hygienic precision mixers.
So far, the market has been dominated by conical screw mixers, in which a screw conveyor transports the mix upwards. At the same time, the screw moves in a circle along the cone wall. Since such conical screw mixers also work well as large mixers, they can be found all over the world. However, they have two disadvantages:
1) You need an extremely large amount of vertical installation space.
2) You need a gearbox in the mixing chamber to drive the auger.
The vertical single-shaft mixer with rigid mixing shaft also achieves excellent mixing qualities. Can't such a mixer also be used as a large mixer?
Yes, existing amixon® mixers can be used very well as large mixers and they are already in use worldwide. But not every operator needs short mixing times of e.g. 4 to 12 minutes. Please refer to the attached table. Two amixon® mixers for 20 m³ batches are compared there.
A vertical amixon® single-shaft mixer delivers ideal mixing qualities, but the speed of the mixing tool should not be less than 4 to 7 revolutions per minute. This results in a circumferential speed of 0.67 to 1,17 m/s for a 20 m³ mixer with a mixing chamber diameter of 3.2 m. In this case, this means that the drive motor must provide a drive power of over 140 kW. With a Gyraton® mixer, it is just 24 kW.
What would be the effect of a reduction in speed to 1 or 2 revolutions per minute? Couldn't this be compensated by doubling or tripling the mixing time?
Unfortunately, this compensation is not possible at will. Here, physics sets limits. For mixing, the speed should not be reduced below 4-5 rpm. The spiral mixing tool only generates rotation in the centre. For mixing, however, it is necessary that the particles move relative to each other. This happens more effectively the further away the mixed goods are from the centre. The speed of the mixing arm is equal to the angular speed multiplied by the radius. If the speed of the mixing tool is reduced too much, the circulation flow in the centre comes to a standstill. Mixing is then no longer possible.
How are the application areas for Gyraton® mixers defined?
The Gyraton® mixer is a good solution when one or more of the following requirements must be met:
- if the batch size is at least 3 m³ and at most 70 m³
- if the bulk materials flow well,
- when it comes to poorly flowing goods,
- when heterogeneous compositions of substances are involved,
- for time-fixing goods
- for moist bulk solids
- if nanoparticles are involved
- for particularly light fabrics
- if heavy metal or ceramic powders are involved
- if special hygienic conditions have to be observed
- if sterile goods are involved
- if inert conditions must be maintained (nitrogen atmosphere)
- if the large mixer is to serve simultaneously as a continuous mixer and as a buffer.
- if the mixer is to be emptied completely
What are the possibilities to test the Gyraton® mixer?
A Gyraton® mixer with a gross volume of 4.8 m³ is available in the technical centre. This allows test batches of up to 3m³ to be mixed effectively. Conducting trials is strongly recommended. This allows us to collect all performance data for reliable extrapolation to larger Gyraton® mixers. We ourselves were very surprised at how economically and efficiently the mixer works.
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