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Dry Powder characteristics impact the mixing uniformity
Time 2024-04-03 Browsing times 次
At present, we have encountered the food, chemical, metal powder no matter what the chemical composition of the powder material, its external physical properties have the following several important indicators, these indicators have an significant impact on the dry powder mixer.
1, Dry powder specific gravity and its influence on the mixing process
The specific gravity of powder is usually expressed by the specific gravity of loose and the shock of the earthquake. Typically, the powder density is between 0.2-2.0, so that the powder and other powder are mixed with a relatively easy to mix evenly. If it less than 2 or higher than 0.5 of the powder mixed with other powder on the relative difficulty. Because the powder is easy to float too light, too heavy powder easy to sink to the bottom, difficult to mix process.
For example, the following figure is the weight of the pine resin powder is 0.4 grams / cubic centimeter, the following figure is the right of the shock of the resin powder is 0.48 g / cubic centimeter. It can be seen that there is a great change in the density of the powder.
2, The fluidity of powder and its effect on the mixture
The flow of the powder can be expressed in a pile of powder angle (left), can also be used to measure the flow of the instrument to measure (figure below). The powder is not good, because the friction of the powder surface is larger than that of the bulk powder is mixed with the surface of the powder. But it is also good, once the mixture is not easy to appear mixed two segregation, stratification phenomenon. The powder with good fluidity, which is less than 30 degrees, is very easy to realize the mixed uniform and the mixing time is short. Can not ignore the other side of things, that is, the flow of a good powder in the mixture after the mixing, transportation will produce a new segregation, stratification phenomenon.
3, Dry Powder particle size and its effect on the mixture
The particle size is usually used to represent the mesh, suitable for mixed particle size is 50 mesh to 300 mesh. The powder is not easy to be integrated into the main powder, and is often stored at the bottom of the body of the 50. Above 300 purpose small powder because of the head is too small, personality has changed, is usually the smaller the powder is more active, the more easily floating in the powder caused by the mixed difficulties.
For example, the following is the 2000 purpose of pigment powder, easy to float on the top of the material, not easy to mix; the bottom right is the 20 purpose of the crystallization of salt particles, in the mixing process is likely to remain at the bottom of the container.
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4, Homogeneous mixture
The so-called homogenization, is to prepare a mixture of several powder, their density, particle size, the basic approach to liquidity, which is the ideal mixed conditions, mixed work efficient and thorough.
The left shows 650 objective reduction of iron, the proportion is 3.8, the right is 800 mesh copper powder, the proportion is 4. The difference between the two kinds of powders is small, which is homogeneous and mixed, and if they are mixed together, the mixture is relatively simple.
5, Differentiation mixing process
We take over the mixed task is often mixed, that is to be mixed with several powder, their density, particle size, liquidity, there are differences, or difference, which leads to a lot of mixed process problems. Such as weight and weight of the powder is not easy to mix the problem, not easy to mix the problem, the problem of mixed flow is not good, the flow of the difference is too large and so on.
The left figure is 800 of the flour, the right figure is 20 of the salt particles. Both particle size difference is very big, belong to the difference mixed, so these two kinds of powder evenly mixed together more difficult.
