Gadolinium: Mixed Rare-Earth Chlorides Reduced with Calcium in Tantalum, Samarium Left in the Slag (Spedding and Daane, US 2,714,554)

Gadolinium is hard to free from samarium and europium by chemistry. Spedding and Daane turned the mixed oxides into chlorides and heated them with calcium in a tantalum crucible: only the gadolinium chloride is reduced, so the metal pools at the bottom and the samarium and europium wash away with the slag. Result: gadolinium metal with no detectable samarium (Example I: 21.5 g from 40 g of chlorides). Source: F. H. Spedding and A. H. Daane, US 2,714,554 (1955). Hydrogen chloride gas and strong hydrochloric acid are corrosive; hot work at 1500 °C under argon; calcium reacts with water. Picture drawn by Youblob.