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Mixing is a key operation for many processes -- a necessity when two or more ingredients must be blended together. We are often asked to provide a definition of mixing versus agitation or blending. Sounds simple enough, but not so when you add other "mixing" terms such as dispersing, hydrating, suspending or emulsifying! In other words, depending upon the ingredients involved, "mixing" or "blending" may not properly describe the operation required. The following are brief descriptions to define each situation
Mixing:
The generic term for the operation encompassing all the variations that follow.
Agitating:
Typically defined as a low speed blending operation with turbine type blades or paddles.
Blending:
Mixing or agitating two or more miscible liquids of similar viscosity (or solids only) and density, often done inside a vertical helical screw blender.
Dissolving:
Where the dissolution of a solid in a liquid is necessary, as with salt or sugar solutions. Simple agitation techniques are normally sufficient, although high shear techniques are required when other solids (ingredients) may block dissolution of the primary solid or when faster dissolution would be beneficial.
Dispersing:
The action of scattering immiscible particles, droplets or gas bubbles in a matrix liquid. The results can properly be called dispersions, but more often they are given more specific names:
◙ Suspension, when solid particles, usually above colloidal size, are dispersed
◙ Emulsion, when droplets are dispersed, such as oil in water or water in oil
◙ Lyosol, when air or gas bubbles are dispersed
Homogenizing:
This term usually applied to a very intense mixing action, but literally it only means that all components are so thoroughly mixed that they are "made alike". This term should not be limited to the action of one particular type of equipment.
Hydrating:
Many ingredients when used as binding or stabilizing agents will "swell" when activated by high shear and attach themselves to other molecules. Hydrocolloids such as gums, carrageenan, CMC, etc., require a high shear device to be thoroughly hydrated.
More than Mixing - Size Reduction:
In order to speed up the mixing process, modern machines introduce a high degree of kinetic energy. This very often results in a reduction of particle or droplet size. This can mean the break-up of agglomerations, and can be done in batch or in-line mode, or more typical is the shear action of tearing droplets apart or the crushing or slicing of solid particles.
If any of these mixing operations fit your requirements, or if you have been struggling with a low speed agitator where high shear equipment may be more appropriate, call us toll free at +92-42-6856744 for more information about our mixing equipment specifically engineered for difficult-to-process ingredients. |