Rhenium mine production

Before scmbbing procedures were estabUshed for copper ore, most of the rhenium was lost as the volatile (Re202). A small portion, perhaps 10%, was retained in flue dust, which was processed to give the metal. A commercial flotation (qv) process for the recovery of the molybdenite by-product is available that permits a high recovery of molybdenum and rhenium. This process is used at the Caridad copper mine in Mexico. 

Molybdenites from porphyry Cu deposits have Re contents that range from 59 ppm (Catface) to as high as 1863 ppm in the Island Copper deposit. The latter is notable for its rhenium production during its operation from 1971 to 1994, the Island Copper mine produced about 27 t Re (Perello et al. 1995). In foreign porphyry Cu deposits, the rhenium content of molybdenite is as high as 3200 ppm Re (e.g., Cerro Verde, Peru). 

Compounds of the composition [ReOCl3(N N)] have also been isolated with pyridine-2-aldi-mine and rr-acidic arylazopyridine and arylazoimidazole ligands." The products (101) are readily reduced by oxygen atom transfer reactions from Re to phosphorus atoms of phosphines which results in the formation of rhenium(III) complexes. Depending on the reaction condition and the phosphines used either mononuclear or binuclear compounds are formed." " Azo splitting reactions with arylazopyridines give access to arylimido and binuclear oxo/imido com-plexes. "" ... 

Humans have at all times made use of the components of the earth s crust. As a consequence of the discovery that even rare materials may have technically interesting properties, there has been a drive to widen the exploitation of natural resources. New separation methods have made the extraction of desirable elements possible. Such rare elements are often obtained as by-products of the mining of common ores. Gold and platinum, for instance, are present in the anode sludge from electrolytic copper refining. The mineral molybdenite, a sulfide, is roasted at 800°C to the oxide from which molybdenum metal and its alloys are produced. During the roasting process the oxide of a rare element, rhenium, volatilizes and its compounds can be extracted from the gas phase as a by-product. Several examples of this type are treated in the different element chapters of this book. 

The total world rhenium production in mines is estimated [29.4] at 28 400 kg for the year 2000, although this figure is uncertain. A value of 12 600 kg is included for the USA, although the production figure is secret. It has been calculated from the official values for MoS production in the USA. The US consumption of rhenium in 2000 (from domestic sources and import) was 32 000 kg, a considerable quantity considering that a production goal of 1 g was reached only 71 years earHer. 

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