Optimization of Silo of Vertical Intensive Mixer
Source: internal company
The mixing of powder materials is very common in industrial production and occupies a very important position in the production process. It is widely used in metallurgy, pharmacy, construction and other aspects. Vertical high intensive mixer is an important equipment in mine material production system. Horizontal mixer has been used for a long time, but its mixing effect is poor and energy consumption is very large. The vertical multi-propeller high intensive mixer being developed lacks design theory and experience, and there are many key technologies to be overcome. According to EDEM discrete element simulation method, the movement process of the mixer bin is simulated, and the rotation parameters of the mixer bin are optimized to improve the mixing effect and service life of the mixer.
Researchers from all over the world have studied the structural optimization of material mixing equipment. Based on the development process of structural improvement research on powder mixing equipment, the mixing performance factors studied at this stage include: blade inclination angle, blade distribution, rotor shaft rotation speed steering, several parameters of mixer, etc.
Brief Introduction of Powerful Mixer
Strong mixer is the key equipment in the pellet production line in the iron and steel metallurgy industry, which is used for blending the mixture. In order to improve the pelletizing performance, 1%-2.5% bentonite was added to the mixture as binder. The mixing uniformity of bentonite directly affects the quality of ball pressing. Due to the light specific gravity of bentonite and the low content of components in the mixture, the common mixer cannot uniformly mix bentonite in the material.
1. Establishment of Vertical Powerful Mixer Model
Solidworks 3D modeling software. As shown in FIG. 1, the main components of the mixer structure are simplified.
Fig. 1: Schematic diagram of main structure of mixer
1. Feed port 2. Main paddle 3. Wall scraper 4. Silo 5. Second auxiliary paddle 6. Discharge port 7. First auxiliary paddle
2. Working Principle of Vertical High Intensive Mixer
The drive motor drives the main propeller shaft to rotate at a faster speed. The rotation speed is positive, but the two auxiliary rotor shafts rotate in opposite directions at faster speeds. The silo runs at a lower speed and turns in the same direction as the main propeller shaft. As different rotation directions will generate vortex flow in the silo, the rotation of the two auxiliary paddle shafts will cause the material particles entering through the feed port to form counterclockwise vortex flow, and the main paddle shaft and the silo form clockwise vortex flow, which is relatively staggered with the materials to form relative convective mixing. Driven by vortex flow, the spatial position and speed of material particles keep changing, thus making them evenly distributed in the silo.
3. Soft sphere model theory and particle point contact model theory
The premise of uniform mixing of powder materials is the contact of particles. In theory, there are currently three models to solve the particle contact problem: spherical particle contact theory, soft sphere model and hard sphere model. The soft ball contact model theory is to simplify the normal force when dealing with particle-to-particle contact, and the normal force is defined by spring and damper. A slider is added to the simplification of tangential force compared with normal force, and parameters such as elastic coefficient and damping coefficient are introduced for simplified calculation.
By improving the rotation parameters of the silo of the vertical high intensive mixer, dead corners are eliminated to a certain extent and the mixing function of the mixer is optimized. The influence of silo rotation on the elimination of dead angle of mixer is qualitatively summarized, and the appropriate silo rotation speed is proposed from the perspective of energy saving and mixing effect.