Mixed uniformity is an important index to evaluate the quality of feed processing, so choose a good feed mixer is very important to guarantee the feed pellets quality, at present, the most widely used mixer in feed pellet plant is horizontal twin shaft paddles mixer and horizontal ribbon mixer.
(1)Horizontal Double-shaft paddle mixer:
Horizontal Double-shaft paddle mixer is consists of machine body, paddle rotor, liquid adding nozzle, discharge door and a transmission mechanism. The machine body is double groove shape and section shape is W shape, the body top cover has two feed inlets, and the two grooves each have a discharge outlet at the bottom. Two rotors are installed in the body, and the rotor is composed of a shaft and multiple sets of paddles.
When working, after the material is added, it is agitated by two paddle rotors rotating in opposite directions. Because the paddles have several special angles, the material is mixed in all directions, and at the same time, it forms weightless zone at the intersection overlap of the two rotors. In this area, regardless of the shape, size, and density of the material, can cause the material to lose weight instantaneously, resulting in a rapid and effective mix.
This mixer has the following features compared with other mixers:
1 The mixing speed is fast, usually the mixing time of a batch of feed is 45s to 60s, which is more than 3 times faster than other types of mixers;
2 the mixing uniformity is good, up to 5% or less;
3 the viscous materials can be mixed and added liquid up to 30%, raw materials can still be mixed evenly;
4 because of adopt paddles structure, the mixing uniformity is affected by the fullness coefficient of the material is small, the fill factor is 0.1 to 0.8.
(2) Horizontal ribbon mixer
The horizontal ribbon mixer consists of machine body, rotor, feed port, discharge port and transmission mechanism. The body is U-shaped and the feed inlet is at the top of the machine. You can select 1~2 feed inlets according to the different requirements of the feeding position. The discharge outlet is at the bottom. The discharge gate has several types including full-length discharge, end discharge and middle discharge. The full-length discharge, also known as a large opening, is characterized by a fast discharge and a small amount of residual material. However, the full-le ngt discharge door is long and is subjected to great force during work. After a period of use, the door is easily deformed. Once the material door is deformed, it can not close tightly, and will easily occur leakage during the mixing process, which affects the mixing effect. The middle discharge and end discharge, although with reliable performance, but discharge need long time and more residue. Some new models adopt multi-stage doors and several discharge ports at the bottom of the mixer. This new model combines the two types of discharge methods described above and also overcomes the defects in the above two types of discharge methods.
The rotor consists of main shaft, support rod, spiral ribbon. The spiral ribbon includes an inner spiral ribbon and an outer spiral ribbon, which are respectively rotate to the left and right. When one spiral ribbon conveys the material from one end of the mixer to the other, the other one ribbon conveys the material in the opposite direction. In the mixer design, the inner ribbon should be wider than the outer ribbon. Make the conveying capacity of the two inner and outer ribbons equal, so as to ensure the material level of both the left and right ends is basically same.
During operation, usually feed the materials after idling start. After the raw material enters the mixer, each part material is pushed by the ribbon , so that the materials in different parts are constantly turning, convection, diffusion or insertion continually. In this way, the feed material is evenly mixed, and the mixed feed is discharged from the discharge port. With this kind of ribbon mixer, the mixing time is usually within 2 to 6 minutes, and the coefficient of variation of the mixing uniformity can be up to 7%.
The horizontal ribbon mixer has a high mixing speed and short stirring period, and can achieve a better mixing effect even when the stirring dilution is relatively large. Horizontal ribbon mixers can not only mix well-dispersed materials, but also can mix materials with poor dispersion and large adhesion, and can add a certain amount of liquid feed if necessary. When adding fat or molasses, the amount can be up to about 10%. However, the horizontal ribbon mixer needs large occupation area and large supporting power.
Except for the above two mixers, there are also horizontal paddle type continuous mixer in the market, it consists of machine body, rotation axis, paddle, auger and transmission mechanism. During work, the raw materials weighed according to the formula are continuously fed into the mixer from the inlet of the mixer. The paddles push the material in a one-way flow and are discharged from the discharge port. The paddles are arranged in a helix, the tilt angle is adjustable, the distance is 300mm, and the length of the mixer is more than 5m. This kind of mixer is with simple structure, low cost, can do continuous working, but is very long and with large residue, not suitable for produce different kind of products, and with poor mixing effect.