Editing Mixing (process engineering) (section)

{{Short description|Process of mechanically stirring a heterogeneous mixture to homogenize it}}
{{Use dmy dates|date=October 2014}}
{{continuum mechanics|cTopic=fluid}}
In industrial [[process engineering]], '''mixing''' is a [[unit operation]] that involves manipulation of a [[Homogeneity and heterogeneity|heterogeneous]] physical system with the intent to make it more [[homogeneous mixture|homogeneous]]. Familiar examples include [[pump]]ing of the water in a swimming pool to homogenize the water temperature, and the stirring of [[pancake]] batter to eliminate lumps (deagglomeration).

Mixing is performed to allow heat and/or mass transfer to occur between one or more streams, components or phases. Modern industrial processing almost always involves some form of mixing.<ref name=ullmann>Ullmann, Fritz (2005). Ullmann's Chemical Engineering and Plant Design, Volumes 1–2. John Wiley & Sons. http://app.knovel.com/hotlink/toc/id:kpUCEPDV02/ullmanns-chemical-engineering</ref> Some classes of [[chemical reactor]]s are also mixers.

With the right equipment, it is possible to mix a solid, liquid or gas into another solid, liquid or gas. A [[biofuel]] fermenter may require the mixing of microbes, gases and liquid medium for optimal yield; organic [[nitration]] requires concentrated (liquid) [[nitric acid|nitric]] and [[sulfuric acid]]s to be mixed with a [[hydrophobic]] organic phase; production of pharmaceutical tablets requires blending of solid powders.

The opposite of mixing is [[Separation process|segregation]]. A classical example of segregation is the [[brazil nut effect]].
[[File:Agitated vessel.svg|thumb|250px|Schematics of an agitated vessel with a [[Rushton turbine]] and baffles]]

The [[Mixing (mathematics)|mathematics of mixing]] is highly abstract, and is a part of [[ergodic theory]], itself a part of [[chaos theory]].