Major Tantalum Metal Producers

Cabot Performance Material (1996) Technical Note No. 505-95-5M Tantalum and Tantalum Alloys. Boyer-town, PA. 

Droegkamp, R.E. SCHUSSLER, M. LAMBERT, J.B. Taylor, D.F. (1984) Tantalum and tantalum compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed. Vol. 22. Wiley-lntersciences, New York, pp. 541-564. 

FairbroTHER, F. (1967) Chemistry of Niobium and Tantalum. Elsevier, New York. 

Hampel, C.A. (ed.) (1967) Rare Metals Handbook, 2nd ed. Reinhold, New York. 

Lambert, J.B. (1991) Refractory metals and alloys. In ASM Handbook of Metals Series, 9th ed. Vol. 2 Properties and Selection of Nonferrous Alloys and Special-Purpose Materials. American Society of Metals (ASM), Materials Park, OH, pp. 557-585. 

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There are an estimated 800 plants in the U.S. involved in the primary or secondary recovery of nonferrous metals. These plants represent 61 subcategories. However, many of these subcategories are small, represented by only one or two plants, or do not discharge any wastewater. This chapter focuses on 296 facilities that produce the major nonferrous metals [aluminum, columbium (niobium), tantalum, copper, lead, silver, tungsten, and zinc]. The volume of wastewater discharged in this industry varies from 0 to 540 m3/T (0 to 160,000 gal/t) of metal produced.13 The global size of the industry is reflected in Table 3.1 (reported in 1000 USD) for the top 20 export countries for nonferrous base metal waste and scrap.4 Here T = metric ton = 1000 kg = 2204.6 lb, t = 2000 lb. 

Anodic Oxidation. The abiUty of tantalum to support a stable, insulating anodic oxide film accounts for the majority of tantalum powder usage (see Thin films). The film is produced or formed by making the metal, usually as a sintered porous pellet, the anode in an electrochemical cell. The electrolyte is most often a dilute aqueous solution of phosphoric acid, although high voltage appHcations often require substitution of some of the water with more aprotic solvents like ethylene glycol or Carbowax (49). The electrolyte temperature is between 60 and 90°C. 

In the second part of the 20th century, the tantalum capacitor industry became a major consumer of tantalum powder. Electrochemically produced tantalum powder, which is characterized by an inconsistent dendrite structure, does not meet the requirements of the tantalum capacitor industry and thus has never been used for this purpose. This is the reason that current production of tantalum powder is performed by sodium reduction of potassium fluorotantalate from molten systems that also contain alkali metal halides. The development of electronics that require smaller sizes and higher capacitances drove the tantalum powder industry to the production of purer and finer powder providing a higher specific charge — CV per gram. This trend initiated the vigorous and rapid development of a sodium reduction process. 

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