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Zone melting (or zone refining, or floating-zone method, or floating-zone technique) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind ...
Pfann is known for his development of zone melting which is essential to the semiconductor industry. As stated in an official history of Bell Labs, "Timely invention of zone refining by W.G.Pfann ... was a major contribution that helped bring the impurities in germanium and silicon under control." [1]
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 ...
Refining is the removal of impurities from materials by a thermal process. This covers a wide range of processes, involving different kinds of furnace or other plant. The term "refining" can also refer to certain electrolytic processes. Accordingly, some kinds of pyrometallurgical refining are referred to as "fire refining".
In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining the final material is chemically identical to the raw material. Refining thus increases the purity of the raw material ...
The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in production, refinement, distribution, and many other aspects of the petroleum industry.
HollyFrontier Cheyenne Refining, LLC v. Renewable Fuels Association , 594 U.S. ___ (2021), was a United States Supreme Court case dealing with exemptions from blending requirements for small refineries set by the Renewable Fuel Standard program.
Zinc smelting is the process of converting zinc concentrates (ores that contain zinc) into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point.