Mixed quality control in the process of additive premix production
A process that coexists simultaneously with the interaction of shearing and separation. All factors that affect these effects will affect the mixed mass, and the main factors are as follows.
The influence of the 1.1 model
The main mixing modes are different, and the mixing strength varies greatly. For example, the horizontal screw mixing machine, which is mainly composed of convection, is superior to diffusion based vertical screw mixer in mixing time, mixing quality and residue. Therefore, it is very important to choose the right mixer.
The effects of the physical properties of the 1.2 mixed components
The physical properties mainly refer to the density, granularity, surface roughness, moisture, dispersion and mass of the material. The smaller the difference of these physical properties, the better the mixing effect. The more difficult it is to separate after mixing, the smaller the proportion of a component in the mixture is, the greater the dilution ratio is, the less likely it is to mix. In order to reduce the re segregation after mixing, viscous liquid components, such as molasses, can be added to other components when the other components are close to completion, so as to reduce their dispersion and reduce the separation effect.
The influence of the 1.3 operation
Mixing time and feed order will affect the mixing quality, so the mixing time and the proper feeding order should be guaranteed.
1.4 effect of static electricity
Materials such as vitamin B2, folic acid and minerals will be adsorbed on the wall of the machine because of the electrostatic effect. It is necessary to properly connect the body to the ground and add antistatic agents to prevent the effect of static electricity.
Evaluation method of mixing uniformity
The general evaluation method of the homogeneity is, in the mixer specific position or in the mixer outlet at a certain time interval from several number of samples were measured for each sample contained a detection component content, and then press type to calculate the coefficient of variation.
CV=S/X * 100%: S - the standard deviation of the content of the detected components in each sample of the mixture;
X - the mean value of the content of the detected components in each sample of the mixture.
The variation coefficient indicates the deviation of the standard deviation of the sample relative to the mean value, and is a relative value. The smaller the coefficient of variation is, the better the mixing uniformity is, and the coefficient of variation under the ideal mixed state is zero. Therefore, in a sense, the coefficient of variation is the degree of inhomogeneity. The standard of feed in China stipulates that the coefficient of variation of the full price matching feed should not exceed 10%, and the additive premix should not exceed 7%.
Quality control in the production of 3 additive premix
In order to obtain a satisfactory quality premix feed, it is necessary to provide a mixer with structural and technical parameters meeting the requirements of the process. Reasonable arrangement of the pre and post processes and the proper use of the mixer itself are all important conditions. In addition, the selection of the carrier diluent, the good loading of the mixer, the proper order of operation and the proper mastery of the mixing time are also necessary.
Selection of 3.1 carrier diluents
All kinds of additives which need to be diluted are generally very thin, so we should choose the thinner which is close to the size and density. Suitable diluent or carrier including feed used components, such as soybean flour, wheat flour, defatted rice bran etc.. Generally, it is the thinner or carrier to choose the material with fine particle size and no dust, and the material that has affinity to the active ingredient in the additive.
If the diluent or carrier is properly chosen, the finished product does not need to be transported. The active ingredient in the additive is not very concentrated, and it is not necessary to use the adhesive. Oil should be used if the pre - mixed finished product needs to be transported in a long distance. The biggest disadvantage of using oil is that a part of the active ingredient of the additive is stranded on the blade of the mixer, affecting the cleaning.
Feeding of 3.2 mixer
In order to add a variety of components in the mixture depends on the machine in the form of general order is as follows: the first 80% diluent or carrier into the mixing machine; the active ingredients and then weighing well spread to the diluent or carrier, some artificial device placement is not convenient, the active component by mechanical method and then sent to the general; in the remaining 20% of the diluent or carrier.
3.3 remove or reduce the storage and transportation process of mixed premixture
In the process of material transportation, due to the effect of gravity, wind, centrifugal force, friction force and so on, the mixed materials have changed greatly. The longer the transportation distance is, the greater the drop, the more serious the classification is. Therefore, it is better to directly pack and pack the mixed materials, so as to avoid or minimize the transportation and dropping of the mixed materials, and do not use the screw conveyor or bucket elevator as much as possible. The height of the bin can not be too high, so as to reduce or eliminate the separation or grading of the mixture.
For each batch of mixture must be recognized clearly, the packaging bag has a clear sign, it is best to use colored symbols or labels to distinguish them.
Rational use of 3.4 mixer
3.4.1 suitable loading
No matter what type of mixer, suitable loading is the prerequisite for the normal work of the mixer and the expected effect. If loading is too much, on the one hand, it will overload the mixer, and more importantly, too much charging will affect the mixing process of the machine, resulting in the decrease of mixing quality. If too little loading is applied, it will not give full play to the efficiency of the mixer, and it will also affect the mixing quality. So no matter in which mixer, the loading degree of material should be controlled effectively, so as to ensure the normal operation of the mixer and make the feed after mixing meet the quality requirement.
A batch horizontal screw type mixer has a full coefficient of 0.6 to 0.9.