This precious metal you’ve never heard of has reached record highs

The chances are good unless you’re an expert physicist you’ve never heard of Ruthenium. Despite its relative obscurity, the rare transition metal has reached a record high price due to new applications beyond its typical usage as a minor component of platinum ores.

Roughly 12 tonnes of ruthenium are mined each year with world reserves estimated as 5,000 tonnes. The composition of the mined platinum group metal (PGM) mixtures varies widely, depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2% (1992). Ruthenium, osmium, and iridium are considered the minor platinum group metals.

Ruthenium, like the other platinum group metals, is obtained commercially as a by-product from nickel, and copper, and platinum metals ore processing. During electrorefining of copper and nickel, noble metals such as silver, gold, and the platinum group metals precipitate as anode mud, the feedstock for the extraction.

The metals are converted to ionized solutes by any of several methods, depending on the composition of the feedstock. One representative method is fusion with sodium peroxide followed by dissolution in aqua regia, and solution in a mixture of chlorine with hydrochloric acid.

Osmium, ruthenium, rhodium, and iridium are insoluble in aqua regia and readily precipitate, leaving the other metals in solution. Rhodium is separated from the residue by treatment with molten sodium bisulfate. The insoluble residue, containing Ru, Os, and Ir is treated with sodium oxide, in which Ir is insoluble, producing dissolved Ru and Os salts. After oxidation to the volatile oxides, RuO 4 is separated from OsO 4 by precipitation of (NH4)3RuCl6 with ammonium chloride or by distillation or extraction with organic solvents of the volatile osmium tetroxide. Hydrogen is used to reduce ammonium ruthenium chloride yielding a powder.

The product is reduced using hydrogen, yielding the metal as a powder or sponge metal that can be treated with powder metallurgy techniques or argon-arc welding.