U.S.Geological Survey (USGS): Rhenium

Statistics and Information: Rhenium (Re), the last naturally-occurring element to be discovered, was discovered in Germany in 1925. 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. These alloys found important applications in industry that resulted in a great demand for the rhenium produced from the molybdenite fraction of porphyry copper ores. Important uses of rhenium have been in platinum-rhenium catalysts, used primarily in producing lead-free, high-octane gasoline and in high-temperature superalloys used for jet engine components.

Rhenium
(Data in kilograms of rhenium content unless otherwise noted)

U.S. Domestic Production and Use: During 2008, ores containing rhenium were mined at eight operations (four in Arizona, and one each in Montana, Nevada, New Mexico, and Utah). Rhenium compounds are included in molybdenum concentrates derived from porphyry copper deposits, and rhenium is recovered as a byproduct from roasting such molybdenum concentrates. Rhenium-containing products included ammonium perrhenate (APR), metal powder, and perrhenic acid. The major uses of rhenium were in petroleum-reforming catalysts and in superalloys used in high-temperature, turbine engine components, representing an estimated 20% and 70%, respectively, of the end use. Bimetallic platinum-rhenium catalysts were used in petroleum-reforming for the production of high-octane hydrocarbons, which are used in the production of lead-free gasoline. Rhenium improves the high-temperature (1,000° C) strength properties of some nickel-based superalloys. Rhenium alloys were used in crucibles, electrical contacts, electromagnets, electron tubes and targets, heating elements, ionization gauges, mass spectrographs, metallic coatings, semiconductors, temperature controls, thermocouple.

U.S. Recycling: Small amounts of molybdenum-rhenium and tungsten-rhenium scrap have been processed by several companies during the past few years. All spent platinum-rhenium catalysts were recycled.

U.S. Import Sources (2004-07): Rhenium metal powder: Chile, 85%; Germany, 7%; Netherlands, 4%; and other, 4%. Ammonium perrhenate: Kazakhstan, 62%; Germany, 10%; Netherlands, 8%; Chile, 6%; and other, 14%.

U.S. Tariff:

U.S. Depletion Allowance: 14% (Domestic and foreign).

Events, Trends, and Issues: During 2008, average rhenium metal price, based on U.S. Census Bureau customs value, was about $1,770 per kilogram, about 9% more than that of 2007. Rhenium U.S. imports for consumption increased by about 22% owing to continued strong demand for superalloys in the gas turbine engine market and improved demand in the catalyst market. Rhenium production in the United States increased by about 8% owing to increased production of byproduct molybdenum concentrates in the United States. The four larger working copper-molybdenum mines maintained byproduct molybdenum production levels near capacity in 2008, while the four smaller operations made incremental increases in production in 2008.

The United States continued to rely on imports for much of its supply of rhenium, and Chile and Kazakhstan supplied the majority of the imported rhenium. Imports of rhenium from Kazakhstan were reduced in 2008 to more normal levels after the influx of stockpiled material in late 2006 and early 2007. Stockpiled quantities of low-grade APR imported into the United States from Kazakhstan in 2007 slowly came into the market after the material was reprocessed. Owing to strong demand, both APR and metal powder spot prices rose sharply in 2007. Basic-grade APR rose from about $4,600 per kilogram in January to about $8,200 per kilogram in December. Metal powder rose from about $5,950 per kilogram in January to about $9,700 per kilogram in December. These trends continued in 2008 with APR rising from $8,200 per kilogram in January to $9,700 in August before retreating to about $8,500 per kilogram in November. Metal powder rose from about $9,000 per kilogram in January to about $11,900 per kilogram in October before retreating to about $9,900 per kilogram in November.

Owing to the scarcity and minor output of rhenium, its production and processing pose no known threat to the environment. In areas where it is recovered, pollution-control equipment for sulfur dioxide removal also prevents most of the rhenium from escaping into the atmosphere.

World Mine Production, Reserves, and Reserve Base:

World Resources: Most rhenium occurs with molybdenum in porphyry copper deposits. Identified U.S. resources are estimated to be about 5 million kilograms, and the identified resources of the rest of the world are approximately 6 million kilograms. In Kazakhstan, rhenium also exists in sedimentary copper deposits.

Substitutes: Substitutes for rhenium in platinum-rhenium catalysts are being evaluated continually. Iridium and tin have achieved commercial success in one such application. Other metals being evaluated for catalytic use include gallium, germanium, indium, selenium, silicon, tungsten, and vanadium. The use of these and other metals in bimetallic catalysts might decrease rhenium’s share of the existing catalyst market; however, this would likely be offset by rhenium-bearing catalysts being considered for use in several proposed gas-to-liquid projects. Materials that can substitute for rhenium in various end uses are as follows: cobalt and tungsten for coatings on copper X-ray targets, rhodium and rhodium-iridium for high-temperature thermocouples, tungsten and platinum-ruthenium for coatings on electrical contacts, and tungsten and tantalum for electron emitters.

(e) Estimated.
(1) Estimated amount of rhenium recovered in association with copper and molybdenum production.
(2) Estimated rhenium recovered from roaster residues from Belgium, Chile, and Mexico.

U.S. Geological Survey, Mineral Commodity Summaries, January 2009