Usually this type of mixing is applied for free-flowing and coarse materials. After a certain mixing time the ultimate random state is reached. With progressing time the mixture becomes more randomly ordered. This type of mixing leads to a less ordered state inside the mixer, the components that must be mixed are distributed over the other components. In the case of convective mixing material in the mixer is transported from one location to another. In powder two different dimensions in the mixing process can be determined: convective mixing and intensive mixing. One example of a solid–solid mixing process is mulling foundry molding sand, where sand, bentonite clay, fine coal dust and water are mixed to a plastic, moldable and reusable mass, applied for molding and pouring molten metal to obtain sand castings that are metallic parts for automobile, machine building, construction or other industries. Solid-solid mixing can be performed either in batch mixers, which is the simpler form of mixing, or in certain cases in continuous dry-mix, more complex but which provide interesting advantages in terms of segregation, capacity and validation. Machine for incorporating liquids and finely ground solids Blending in a more viscous liquid, such as honey, requires more mixing power per unit volume to achieve the same homogeneity in the same amount of time. If necessary, a spoon or paddle could be used to complete the mixing process. The momentum of the liquid being added is sometimes enough to cause enough turbulence to mix the two, since the viscosity of both liquids is relatively low. Since both liquids are water-based, they dissolve easily in one another.
An everyday example would be the addition of milk or cream to tea or coffee. Mixing of liquids that are miscible or at least soluble in each other occurs frequently in engineering (and in everyday life). Turbulent or transitional mixing is frequently conducted with turbines or impellers laminar mixing is conducted with helical ribbon or anchor mixers. Single-phase blending tends to involve low-shear, high-flow mixers to cause liquid engulfment, while multi-phase mixing generally requires the use of high-shear, low-flow mixers to create droplets of one liquid in laminar, turbulent or transitional flow regimes, depending on the Reynolds number of the flow. The nature of liquids to blend determines the equipment used. Mixing of liquids occurs frequently in process engineering. In this context, the act of mixing may be synonymous with stirring-, or kneading-processes. The type of operation and equipment used during mixing depends on the state of materials being mixed (liquid, semi-solid, or solid) and the miscibility of the materials being processed. A classical example of segregation is the brazil nut effect. A biofuel fermenter may require the mixing of microbes, gases and liquid medium for optimal yield organic nitration requires concentrated (liquid) nitric and sulfuric acids to be mixed with a hydrophobic organic phase production of pharmaceutical tablets requires blending of solid powders. With the right equipment, it is possible to mix a solid, liquid or gas into another solid, liquid or gas.
Some classes of chemical reactors are also mixers. Modern industrial processing almost always involves some form of mixing. Mixing is performed to allow heat and/or mass transfer to occur between one or more streams, components or phases. Familiar examples include pumping of the water in a swimming pool to homogenize the water temperature, and the stirring of pancake batter to eliminate lumps (deagglomeration). In industrial process engineering, mixing is a unit operation that involves manipulation of a heterogeneous physical system with the intent to make it more homogeneous.
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