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Ames process
The Ames process is a process by which pure uranium metal is obtained. It can be achieved by mixing any of the uranium halides (commonly uranium tetrafluoride) with magnesium metal powder or aluminium metal powder.
== History ==
The Ames process was used on August 3, 1942 by a group of chemists led by Frank Spedding and Harley Wilhelm at the Ames Laboratory as part of the Manhattan Project.〔Frank H. Spedding, Harley A. Wilhelm, and Wayne H. Keller, ("Production of uranium," U.S. Patent no. 2,830,894 ) (filed: 7 Nov. 1947; issued: 15 April 1958).〕 It is a type of thermite-based purification, which was patented in 1895 by German chemist Hans Goldschmidt.〔 H. Goldschmidt, "Verfahren zur Herstellung von Metallen oder Metalloiden oder Legierungen derselben" (Process for the production of metals or metalloids or alloys of the same), Deutsche Reichs Patent no. 96317 (13 March 1895).〕 Development of the Ames process came at a time of increased research into mass uranium metal production. The desire for increased production was motivated by a fear of Nazi Germany developing nuclear weapons before the Allies. The process originally involved mixing powdered uranium tetrafluoride and powdered magnesium together. This mixture was placed inside an iron pipe that was welded shut on one side and capped shut on another side. This container, called a "bomb" by Spedding,〔In laboratory jargon, pressure vessels, such as steel autoclaves and gas cylinders, are commonly called "bombs"〕 was placed into a furnace. When heated to a temperature of , the contents of the container reacted violently, leaving a 35-gram ingot of pure uranium metal. The process was quickly scaled up; by October 1942 the "Ames Project" was producing metal at a rate of 100 pounds per week. The uranium tetrafluoride and magnesium were sealed in a refractory lined reactor vessel, still referred to as a "bomb". The thermite reaction was initiated by furnace heating the assembly to ; the large difference in density between slag and metal allowed for complete separation in the liquid state, yielding slag-free metal.〔The Metal Thorium, Proceedings of the Conference on Thorium , Oct 11, 1956, American Society for Metals & US Atomic Energy Commission, H. Wilhem, Editor, 1958.〕 By July 1943, the production rate exceeded of uranium metal per month. Approximately 1000 tons of uranium ingots were produced at Ames before the process was transferred to industry.〔1972-1973 Ames Laboratory Highlights, Ames Laboratory, Iowa State University, Ames, IA, ERDA 0575〕
The Ames project received the Army-Navy ‘E’ Award for Excellence in Production on October 12, 1945, signifying two-and-a-half years of excellence in industrial production of metallic uranium as a vital war material. Iowa State University is unique among educational institutions to have received this award for outstanding service, an honor normally given to industry.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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