Difference between Solid and Liquid Mixing

Solid mixing - When solids are mixed with solids, liquids with solids, and gases with solids, solids are said to be mixed with solids. The mixing of solids does not create a flow current. Dry solids have high mixing power. Solid mixing is done using blenders and mixers.

Liquid mixing - It is possible to define liquid mixing as the mixing of liquids together. The mixing of liquid-liquid creates a flow current. The mixing power of liquids is lower than that of solids. When mixing liquids, agitators are employed.

Mixtures in the industrial sector include solids to solids (free flowing solids and pasty materials), solids to liquids, solids to gases (reactions), liquids to liquids, and liquids to gases. Mixing liquids with liquids and liquids with gas is considered fluid mixing. Solid's mixing is somewhat similar to the process of mixing low-viscosity liquids; however, there are some important differences between the two. Here are some of them:

• Unmixed materials are carried to a mixing zone adjacent to the impeller by currents of flow created by the impeller. The mixing of heavy pastes or masses of solid particulates can not occur by such currents.
• When mixing solids and pastes, a greater amount of power is required than when blending liquids.
• An "well-mixed" product in fluid mixing usually means that the liquid phase is truly homogenous. It is common for the final paste or powder product to contain two or more discernible phases containing individual particles of varying size. Small random samples of a "well-mixed" product will differ significantly in composition from a larger sample of the same product.

In process engineering (and everyday life), mixtures of liquids that are miscible or at least soluble in each other are common. Milk or cream can be added to tea or coffee as an everyday example. The two liquids easily dissolve in each other because they are both based on water. This process of solid-solid mixing produces mulling foundry molding sand, which is made of sand, bentonite clay, fine coal dust, and water. This mixture is used to form a solid moldable mass from which molten metal can be poured to create metallic parts for automobiles, machine building, construction, etc.

It involves mixing solids with other solids such as free-flowing solids with pasty materials, solids with liquids, solids with gas, liquids with liquids, and liquids with gases in industrial applications.

Solid mixing	Liquid mixing
A mixing of solids can be compared to mixing of liquids of low viscosity.	A fluid mix is usually a liquid-liquid or a liquid-gas mixture.
There are no such currents possible in heavy masses of particulate solids, so mixing has to be done by some other method.	It is the creation of flow currents that transport the unmixed material to areas near the impeller that are responsible for mixing liquids.
Compared to wet solids, dry solids require more power for mixing.	Liquids can be mixed and blended with less power.
Solid mixing often involves the formation of multiple easily distinguishable phases, each of which may contain individual particles of substantial size.	An ideal liquid phase is usually truly homogeneous when it has been well mixed.
The composition of two sample "well-mixed" solids is markedly different.	It is homogenous in nature when a liquid product sample is "well-mixed.".
As mixers and blenders, solid mixing equipment is designed, constructed, and operated differently from liquid mixing equipment.	Liquid agitators are designed, constructed, and operated specifically for mixing fluids.
Designing solid mixers and understanding solid mixing are more an art than a science.	There has been extensive research and understanding of liquid mixing technology.
It is more difficult to mix solids.	It is very easy to mix liquids.

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