Appropriate mixing time

The clear definition of mixing time is crucial for the quality of the mixture in a staged mixer. The mixing time is too short, and the material cannot be fully mixed in the mixer and is discharged, resulting in an inability to ensure the quality of the mixture; If the mixing time is too long, the material will be mixed too much in the mixer, resulting in separation, which will also harm the quality and increase energy consumption.

The clarity of the mixing time lies in the mixing rate of the mixer, which is mainly determined by the model of the mixer. Like a vertical screw belt mixer, it usually takes 3-5 minutes each time, and its length depends on the type and characteristics of the raw materials, such as moisture content, particle size, fat percentage, etc; The mixing time of the two axis blade mixer is less than 2 minutes each time; For rotary mixers, a longer mixing cycle time is specified due to their slower mixing efficiency.

Suitable loading materials

Suitable loading is a necessary condition for the normal operation and achievement of expected goals of any type of mixer. If there is too much loading, on the one hand, it will overload the mixer during operation, and more importantly, excessive loading will harm the entire mixing process of the materials inside the machine, leading to a decrease in mixing quality; If the loading is too small, the high efficiency of the mixer cannot be fully utilized, and it will also harm the mixing quality. Therefore, regardless of the type of mixer, the level of material loading should be reasonably controlled in order to ensure the normal operation of the mixer and to consider the quality requirements of the mixed feed.

The filling index of the segmented vertical screw stacking mixer is generally between 0.6-0.9, and the material level should not exceed the top plan of the motor rotor; The filling index of a two axis blade mixer is generally controlled between 0.6 and 0.85.

Minimize separation as much as possible

All powders with good fluidity often have a tendency towards separation. There are three reasons for separation: ① When materials fall into a pile, large particles fall into the bottom of the pile due to a large inertial force, while small particles with smaller inertial forces may get stuck in the gaps on the pile; ② When the material is shaken, smaller particles tend to move to the bottom, while larger particles tend to move to the top When the mixture is blown open or dusted, separation occurs relatively due to differences in particle size and relative density.

To prevent separation, the following methods are often used: ① Ensure that the particle sizes of various components in the mixture are close to each other; Or by adding liquid to prevent separation Grasp the mixing time, there is no need to mix too much. It is generally believed that the materials should be unloaded before being evenly mixed and mixed throughout the entire transportation or transfer process Reduce the loading and unloading work after mixing to a minimum level. The lower the material falls, flips, or drags, the better. The storage bin after mixing should be as small as possible, and the conveying equipment after mixing should be a belt conveyor, avoiding the need for screw conveyors, bucket elevators, and pneumatic conveying system equipment as much as possible Add anti-static agents to the grounding device of the mixer and the concentrate feed to reduce the separation of the mixture caused by the adsorption effect of electrostatic induction.

Effective practical operation sequence

In the order of feeding, it is generally recommended to add the ingredients with large quantities first or the majority of them into the machine, and then place small and trace amounts of analytical ingredients on top of the materials. Among various materials, those with larger particle sizes are usually added to the mixer first; And those with smaller granularity will be added later. The relative density of materials also varies. When there is a significant difference, the material with lower relative density is usually placed first, followed by the material with higher density.