Commercial rhenium is extracted from molybdenum roaster-flue dusts obtained from copper sulfide ores.
Rhenium is combined with platinum to form catalysts that are used primarily for making lead-free, high-octane gasoline.
The process was so complicated and the cost so high that production was discontinued until early 1950, when tungsten-rhenium and molybdenum-rhenium alloys were prepared.
Little is known about the toxicity of rhenium, but as a precautionary measure, it should be handled with care.
Recycling of used platinum-rhenium catalyst and special alloys allow the recovery of another ten tons/year.
The melting point of rhenium is among the highest of all elements, exceeded only by the melting points of tungsten and carbon.
The usual commercial form of rhenium is a powder, but it can be consolidated by pressing and resistance-sintering in a vacuum or hydrogen atmosphere.
Rhenium (chemical symbol Re, atomic number 75) is a silvery-white, lustrous, rare metal.
In 1994, Nature published a letter describing a rhenium sulfide mineral found condensing from a fumarole on Russia's Kudriavy volcano.
Rhenium is also one of the densest, exceeded only by the densities of platinum, iridium, and osmium.
Naturally occurring rhenium is a mix of 185Re, which is stable, and 187Re, which is radioactive but has a very long half-life.
The name rhenium is derived from the Latin word Rhenus, meaning "Rhine."
Rhenium is widely spread in the Earth's crust, at approximately 0.001 parts per million (ppm), but it is not found free in nature.
Rhenium-molybdenum alloys are superconductive at ten Kelvin (K), and tungsten-rhenium alloys are superconductive around four to eight K, depending on the alloy.
The oxidation states of rhenium include -3,-1,+1,+2,+3,+4,+5,+6 and +7.