Solid mixing and liquid mixing difference
With any process in the chemical industry or technology industry, we look forward to generating the appropriate interaction between materials so that they will progress through the process according to our purpose.
Our deep understanding of mixing shows us that we could make things homogeneous to generate a homogeneous mixture. And it is clear that this is okay when required. We’ve discussed many times what will happen when generating a homogeneous mixture is not required, but sometimes we confuse ourselves and try to provide a more homogeneous method when the process requires a less homogeneous method. For further reading on this topic, you can read our other articles on this website.
Here, I want to discuss another point of view. What is a homogeneous mixture? Since flow dynamics is a multi-dimensional phenomenon, we need to define what is homogeneous for us. This is critical because understanding the level of homogeneity will generate for us an understanding of the process and will explain the results that we get from our process.
The process can be controlled by mainly two kinds of homogeneous levels. The first is macro homogeneity. Macro homogeneity, from the intuitive point of view, is when we generate fluids elements that move, or structural laminas like those we did in the laminate rating, for instance. These laminas and fluid elements are moving into the tank. If we are able to distribute these eddies homogeneously in the tank, we will reach macro homogeneity, macro mixing time. The macro mixing time is the time required to generate homogeneity in the
Any main process in the industry progresses in the liquid phase, in which we add some chemical materials or biological materials like a solid or liquid. The process progresses according to the connection between the materials—the affinity between the materials to generate reaction formulations, dissolutions, or other outcomes.
Now, when we talk about the difference between solid mixing and liquid mixing, we’re talking about the same kind of parameters that can influence the integration of a solid into a liquid or liquid into a second liquid that is not miscible. The mixing parameters that we apply are the same, but the influence of these parameters in the process is completely different.
For instance, when we add solids to a tank and want to progress with a reaction where one of the solids is a reactant, the primary and typical resulting situation is one where the solid is dissolved a little in the liquid. This dissolved part of the solid material will react with the second reactant that we have in the media.
So, the main rate of reaction is normally controlled by the capability of the solid to be dissolved in the liquid phase, and from this step we progress with the reaction. For these kinds of operations, from the mixing point of view, we need to be able to transfer the solid to a liquid phase as fast as possible. The parameters that influence this kind of activity include the turbulence shear rate, which takes the material from the surface of the solids and dissolves it in the liquid media.
A high shear rate will increase the mass transfer, and the work done will be available in the media to react. When we talk about liquid-liquid mixing, one of the two liquids will be in a dispersed phase, and it will be like the solid. This liquid is a particle that moves into the tank. And again, if we want to transfer part of the material that is in the liquid phase to the continuous phase, we will require exactly the same high shear rate that will transfer the material as fast as possible to the liquid phase. This material in the in the continuous phase will be available for the second reactant that we have in the tank. It appears that the same parameters that we use are for the same purpose in the solid-liquid mixing or liquid-liquid non-miscible liquids.
But, what will happen if we apply very high velocity? In the liquid-liquid phase, we might generate emulsification that will never separate. We want the material to separate because we want to obtain only the product that is in the dispersed phase; we want to separate the continuous from the dispersed phase and get the material from the liquid phase. However, creating the solid phase is good because when we increase the shear rate, the solid will continue get be smaller and smaller until this activity is very good for us.
So, here exists the contradiction between the same parameter turbulence shear rate that will be applied in the solid-liquid as high as possible. In the liquid-liquid phase, we could generate an operation problem that, as a consequence, will be completely unsuccessful.
So, this illustrates well why we need to first understand the process, then the connection between the phases, and, finally, what the purpose is. When our purpose is clear, we will adapt our mixing and look for the mixing parameter that will give us a process yielding a viable ravel. We’ll be able to manufacture our material according to the equipment in different scenarios.
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