No matter the type of mixer is, the suitable loading condition is the precondition for the mixer to work normally and get the expected mixing effect.
In batch type mixer, the appropriate filling coefficient of horizontal ribbon mixer is 0.6 ~ 0.8, and the highest material level should not exceed the top of rotor. The filling coefficient of batch type vertical mixer is generally controlled at 0.8 ~ 0.85.The filling coefficient of single-shaft or double-shaft mixer is 0.8 ~ 1.When the bulk density of the material is > 0.6, it shall be calculated according to the mixing amount of each batch. When the bulk density of the material is ≤0.6, the range of bulk density can be considered.
There are a little of various vitamins, medicament and other additives or concentrates in the feed need to be diluted with the carrier to be premix , and then entering the mixer with other materials.
In the feeding sequence, generally the large proportion of the components will be added first or most of this part will be added, then small proportion or trace components placed on the material. In all kinds of materials, the large particle size is generally added to the mixer first, and the small particle size is added later. The density of the material will also have differences, when there is a big difference, generally add the material with small density first, after adding the large one.
This problem does not exist for continuous mixer, but for batch mixer, it is very important to determine the mixing time for the quality of mixed materials:
(1) mixing time is too short, the material which is not fully mixed in the mixer will be discharged, product mixing quality will be affected;
(2) too long mixing time, the material is mixed in the mixer for a long time, which not only causes the increase of energy consumption and the decline of output, but also causes the separation and accumulation of components due to excessive mixing, which reduces the mixing uniformity.
The determination of mixing time depends on the mixing speed of mixer, which is mainly determined by the type of mixer. For example, horizontal ribbon mixer, its mixing mainly by convection, usually 2 ~ 5min each batch, the time depends on the nature of raw materials, such as moisture content, particle size, fat content, etc..For the double shaft high-efficiency mixer mainly use shear and convective mixing, it can generally meet the requirement of mixing uniformity with a shorter mixing period of 40 ~ 60s.
4. Try to avoid separation
In order to avoid separation, the following four methods are adopted:
①Try to make the mixture of the various components of the same particle size, liquid can be also added to avoid separation.
② control the mixing time, do not over-mix, it is generally considered that the material should be discharged before approaching the mixing uniformity, complete the mixing during transportation or transit process
③ Try to decrease the unloading work after mixing, the falling, rolling ,sliding of material should be as little as possible.
④ The mixture should be granulated immediately after mixing
After mixing machine is used for a long time, the sealing of door will appear the problem of aging and wear. The operator should check the mixing machine door part regularly for leakage. Repair and replace the spare part in time if there is leakage.