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What happens during the Ames process for making uranium metal?

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Enrichment of uranium — uranium processing How uranium is enriched to make a nuclear weapon.

The Ames process is a method for producing high-quality uranium metal through the thermal reduction of uranium tetrafluoride (UF₄) using magnesium (Mg).12

In this procedure, granular UF₄ and finely divided magnesium—provided in excess—are placed inside a sealed, refractory-lined container known as a "bomb". The vessel is heated to temperatures between 500 and 700 °C (930 to 1,300 °F), triggering an exothermic reaction. This reaction generates sufficient heat to exceed 1,300 °C (2,375 °F), liquefying the contents into metallic uranium and a slag of magnesium fluoride (MgF₂).1

Once the bomb cools to ambient temperature, the resulting uranium metal is recovered. This material is considered the highest-quality commercial uranium metal available and is suitable for fabrication into nuclear reactor fuel. Developed in 1942 by F.H. Spedding and his colleagues at Iowa State University, the process may also utilize calcium as a substitute for magnesium.12