APPLICATION
The pin mill is used for the final grinding of the process of plaster production, through this process the material achieve an appropriate grain size.
Machine aimed to the micronized of the different kind of nonferrous minerals (clay, shale, bentonite, gypsum, sepiolite, magnesite, phosphate, soft limestone, marble, coke, talc, kaolin, rubble, etc.).
This type of process is fundamental in the lines of clay preparation by dry process in the stage of finished product, the maximum humidity depends on the consistence curve of each material, being usually a low percentage. Domenech has designed and manufactured a new concept for the micronizer mill which has been designed for working through the impact and the friction (thanks to the optional addition of a grill around the rotor). The grill is more efficient and necessary with high humidity which means more adherence and tenacity of the material to treat.
Depending on the model, the entry grain size will have a measure between 0-30mm, the exit size can be between 80-100 µm.
OPERATION
The material goes inside the feeding chute with high tilt angle, especially designed to avoid flow accumulation, entering directly in the center of the grinding rotor crashing with the moving grinding bars accelerating the material almost instantaneously at a speed between 30-55 m/s (more than 200 km/h) depending on the application, through this process is made the first fine crushing. The material due to the gravity and centrifugal acceleration is forced to move from the rotation center of the rotor to the exterior part of itself. The second impact is made against the different static bars, braking until 2-4 m/s almost instantaneously, generating in this point a high grain size reduction. After this, the material is accelerated again through the moving bars, this process is repeated continuously depending on the installed rotor, getting cutting speeds between 55-85 m/s (more than 300 km/h). The grains, which get the desired size, leave the grinding camera by gravity or with the aid of different pneumatic classifiers (baghouses, dynamic separators, etc). The particles with high hardness, high tenacity or with difficult geometry for grinding, they will need several cycles as the indicated before to get the required size and geometry to leave from the grinding camera.
CONSTRUCTION
Structure, entry chute, moving rotor+bars, static rotor+bars, static rotor support with hinge to open, classification grill.
ADVANTAGES
- Feeding geometry highly studied and tested with many types of materials to avoid the formation of obstructions to the entry material, avoiding in many cases the known force feeding through screw conveyors.
- Static rotor support with hinge to open the rotor, the static rotor can be disassembled with only one bolt, leaving the mobile rotor and the grill exposed for inspecting or changing it easily and quickly.
- Sealing through an O-ring of material NBR located inlaid in a machined groove.
- Bearing supports designed and manufactured by Domenech with vibration damping material, provided with a patented shutter system which increases the useful life of the bearings, calculated for a long useful life.
- Grill machined piece to piece to guarantee a fine and uniform pass against the wear and providing an easy maintenance, getting high uniformity in the exit size.
- Interchangeability of different designs of mobile and static rotors with different wear resistance, number and bars geometry according to the material to treat and the desired granulometric curve.
- The grinding bars are manufactured in high resistance and tenacity Steel, machined and joined to the rotor with high precision. We get an operation free of vibrations increasing the bearings life.
- The mobile rotors are 100% interchangeable due to they are machined with the most modern and accurate Computer Numerical Control machinery, being statically and dynamically balanced.
- Possibility of changing the granulometric curve of the product without the necessity of stopping the production. We can do that using a variable frequency drive which can modify the cutting speed for getting the desired range of the grain size.
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