The Preparation of Thorium Metal by Sodium Amalgam Reduction of Thorium Chloride: the Metallex Process

A process, developed at Oak Ridge National Laboratory, produced thorium metal by the continuous reduction of anhydrous thorium tetrachloride with sodium amalgam on a scale up to 3.5 pounds per hour. The salt was vigorously agitated with an excess of sodium amalgam which was produced by the electrolysis of aqueous sodium hydroxide. The resulting slurry of thorium mercuride in mercury was washed free from impurities and reaction by-products with dilute HC1 and water. A solid concentrate of the thorium mercuride was prepared by filter-pressing the dilute slurry. The remaining mercury was removed by vacuum-distillation, resulting in massive metal of about 0.8 of the theoretical thorium density. The metal was fabricated into rods by direct extrusion or by arc-melting followed by extrusion.