• refining
  • The processing of raw material to remove impurities.
Abstract from DBPedia
    Refining (also perhaps called by the mathematical term affining) is the process of purification of a (1) substance or a (2) form. The term is usually used of a natural resource that is almost in a usable form, but which is more useful in its pure form. For instance, most types of natural petroleum will burn straight from the ground, but it will burn poorly and quickly clog an engine with residues and by-products. The term is broad, and may include more drastic transformations, such as the reduction of ore to metal (for which see Refining (metallurgy)). The refining of liquids is often accomplished by distillation or fractionation; this process is useful, for example, for isolating different fractions of petroleum. Gases can be refined in this way as well, by being cooled and/or compressed until they liquefy. Gases and liquids can also be refined by extraction with a selective solvent that dissolves away either the substance of interest, or the unwanted impurities. Many solids can be refined by growing crystals in a solution of the impure material; the regular structure of the crystal tends to favor the desired material and exclude other kinds of particles. Chemical reactions are often used to remove impurities of particular types. The use of silicon and other semiconductors in electronics depends on precise control of impurities. The zone melting process developed by William Gardner Pfann was used to produce pure germanium, and subsequently float-zone silicon became available when Henry Theuerer of Bell Labs adapted Pfann's method to silicon. Types of materials that are usually refined: * metals (see Refining (metallurgy) * petroleum (see Oil refinery) * silicon * sugar (see Sugar refinery) * flour (see Gristmill) * table salt * vegetable oil (see Food oil refinement for food use and Vegetable oil refining for biofuel use) * air * glass

    精製(せいせい、英語:refining)とは、混合物を純物質にする工程、あるいはその技術。化学的に合成したり、抽出などにより得た化合物は、多くの場合、いくつかの化合物の混合物であるため、単一で純度の高いものにするために精製を行う。 重要な精製技術に、再結晶、蒸留、昇華、クロマトグラフィーがある。目的とする純度は、それを用いて何を行うかによって決まり、元素分析のためには高純度にする必要があるが、ほかの用途では大まかな純度で十分となることもある。 再結晶化合物を溶媒に加熱して溶かし、冷却したり溶媒を蒸発させたりすることでより純度の高い結晶を得る精製法。蒸留液体の化合物を加熱し、一度気体にしたのち凝縮させる精製法。再沈殿化合物の溶けた溶液と化合物をあまり溶かさない溶媒(貧溶媒)を混合することで目的の化合物を沈殿として得る精製法。昇華固体の化合物を一度気体にしたのち再び固体として行う精製法。カラムクロマトグラフィーシリカゲル等との親和性の差を利用した精製法。