Iron-group metal powders

The alloy powders of the iron-group metals are of great interest for many industrial applications [1-88]. 

A particularly satisfactory ruthenium catalyst was prepared as follows. Commercial ruthenium powder was fused with a mixture of potassium hydroxide and potassium nitrate (1 part ruthenium, 10 parts potassium hydroxide, 1 part potassium nitrate) preferably in a silver crucible and stirred with a silver spatula. Pusion was complete after 1 to 2 hours. After cooling, the fused mass was dissolved in water a deep red solution of potassium ruthenate resulted, which was heated to boiling. Methyl alcohol was added dropwise to the boiling solution. The reduction of potassium ruthenate to ruthenium dioxide began with the addition of the first drops and went rapidly to completion. The precipitate settled after a few hours. It was washed on a fritted glass plate, first with water acidified with nitric acid and then with distilled water. Finally the catalyst was dried at 110°C. The reduction to metal proceeds just as smoothly under synthesis conditions as by a hydrogen treatment, which latter is usually required with catalysts of the iron group. 

Serendipitous use of measurements of hydrogen retained by metal powders formed by hydrogen reduction of salts has provided a likely explanation for these trends except for iron (no datum) and palladium (exothermic absorption), the trends were the opposite of those above. The amounts occluded are however greater by large factors than those due to simple dissolution, and the metals in question (unlike those in Groups 4 and 5) do not form salt-like hydrides. It was therefore... 

The platinum group metals occur jointly as alloys and as mineral compounds in placer deposits of varying compositions. Ru and Os are separated from the PGM mix by distillation of their volatile oxides, whereas platinum, iridium, palladium, and rhodium are separated by repeated solution and precipitation as complex PGM chlorides, or by solvent extraction and thermal decomposition to sponge or powder. PGM scrap is recycled by melting with collector metals (lead, iron, or copper) followed by element-specific extraction. 

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