Separation process

Some types of separation require complete purification of a certain component. An example is the production of aluminum metal from bauxite ore through electrolysis refining. In contrast, an incomplete separation process may specify an output to consist of a mixture instead of a single pure component. A good example of an incomplete separation technique is oil refining. Crude oil occurs naturally as a mixture of various hydrocarbons and impurities. The refining process splits this mixture into other, more valuable mixtures such as natural gas, gasoline and chemical feedstocks, none of which are pure substances, but each of which must be separated from the raw crude. In both complete separation and incomplete separation, a series or cascade of separations may be necessary to obtain the desired end products. In the case of oil refining, crude is subjected to a long series of individual distillation steps, each of which produces a different product or intermediate. ==List of separation techniques==

• Centrifugation and cyclonic separation, separates based on density differences • Chelation • Chromatography separates dissolved substances by different interaction with (i.e., travel through) a material. • High-performance liquid chromatography (HPLC) • Thin-layer chromatography (TLC) • Countercurrent chromatography (CCC) • Droplet countercurrent chromatography (DCC) • Paper chromatography • Ion chromatography • Size-exclusion chromatography (SEC) • Affinity chromatography • Centrifugal partition chromatography • Gas chromatography and Inverse gas chromatography • Crystallization • Decantation • Demister (vapor), removes liquid droplets from gas streams • Distillation, used for mixtures of liquids with different boiling points • Drying, removes liquid from a solid by vaporization or evaporation • Electrophoresis, separates organic molecules based on their different interaction with a gel under an electric potential (i.e., different travel) • Capillary electrophoresis • Electrostatic separation, works on the principle of corona discharge, where two plates are placed close together and high voltage is applied. This high voltage is used to separate the ionized particles. • Elutriation • Evaporation • Extraction • Leaching • Liquid–liquid extraction • Solid phase extraction • Supercritical fluid extraction • Subcritical fluid extraction • Field flow fractionation • Filtration – Mesh, bag and paper filters are used to remove large particulates suspended in fluids (e.g., fly ash) while membrane processes including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, dialysis (biochemistry) utilising synthetic membranes, separates micrometre-sized or smaller species • Flocculation, separates a solid from a liquid in a colloid, by use of a flocculant, which promotes the solid clumping into flocs • Fractional distillation • Fractional freezing • Magnetic separation • Oil-water separation, gravimetrically separates suspended oil droplets from waste water in oil refineries, petrochemical and chemical plants, natural gas processing plants and similar industries • Precipitation • Recrystallization • Scrubbing, separation of particulates (solids) or gases from a gas stream using liquid. • Sedimentation, separates using vocal density pressure differences • Gravity separation • Sieving • Sponge, adhesion of atoms, ions or molecules of gas, liquid, or dissolved solids to a surface • Stripping • Sublimation • Vapor–liquid separation, separates by gravity, based on the Souders–Brown equation • Winnowing • Zone refining ==See also==