Platinum group metals sources

Secondary Platinum-Group Metals. For many PGM appHcations, the actual loss during use of the metal is small, and hence the abihty to recover the PGM efficientiy contributes greatiy to the economics of PGM use. Typical sources of PGM for secondary refining iaclude jewelry and electronics scrap, catalysts, and used equipment, eg, from the glass industry. 

There are several exceUent sources of information about the platinum-group metals. The exceUent reference work G. Wilkinson, R. D. GiUard, and J. A. McCleverty, eds.. Comprehensive Coordination Chemistry Pergamon Press, Oxford, U.K., 1987, contains iadividual chapters devoted to descriptive chemistry of each element. 

Insoluble impurities fall to the floor of the cell as anode slime. Despite the derogatory name, this material contains precious metals such as gold, silver, and platinum. Anode slime from the electrorefining of nickel11 at Sudbury, Ontario, is a significant source of platinum and palladium as byproducts ( 0.34 g Pt and 0.36 g Pd per metric ton of ore), whereas deposits in the Bushveld complex (Transvaal, South Africa) are so rich in platinum-group metals (Ru, Os, Rh, Ir, Pd, Pt) that the associated Co, Ni, and Cu recovered are considered to be by-products of the lucrative platinum production (4.78 g Pt and 2.03 g Pd per metric ton of ore).7... 

Palladium occurs in combination with platinum and is the second most abundant platinum group metal (pgm), accounting for 38% of pgm reserves. The USSR produces over 50% of the world s palladium, which is more than double that produced in South Africa. Two major sources of the metal are braggite, a mixed sulfide of platinum, palladium and nickel, which contains 16-20% palladium, and michenerite (PdBi3). 

FIGURE 21.2 Primary mineral sources of metals. The s-block metals occur as chlorides, silicates, and carbonates. The d- and p-block metals are found as oxides and sulfides, except for the group 3B metals, which occur as phosphates, and the platinum-group metals and gold, which occur in uncombined form. There is no mineral source of technetium (Tc in group 7B), a radioactive element that is made in nuclear reactors. 

The driving force for tlie development of non-platinum exliaust emission catalysts is the price, strategic importance and low availability of the platinum group metals. Our studies have shown that catalysts based on tin(IV) oxide (Sn02) promoted with chromium and/or copper (Cr-Sn02 and Cu-Cr-Sn02 catalysts) which exhibit excellent three-way catalytic activity - activity which is comparable to that shown by noble metals dispersed on ahunina. This family of materials offers tremendous promise as cheap and efficient catalyst systems for the catalytic conversion of noxious emissions from a variety of sources. In tliis paper we describe tliree aspects of this family of environmental catalysts (1) the synthesis, (2) tlieir characterisation, and (3) their catalytic activity. 

Radziuk B, Rodel G, Stenz H, Becker-Ross H, Florek S (1995) Spectrometer system for simultaneous multielement electrothermal atomic absorption spectrometry using line sources and Zeeman-effect background correction. J Anal At Spectrom 10 127—136 Rao CRM, Reddi GS (2000) Platinum group metals (PGM) occurrence, use and recent trends in their determination. Trends Anal Chem 19 565-586 Rauch S, Lu M, Morrison GM (2001) Heterogeneity of platinum group metals in airborne particles. Env Sci Technol 35 595-599... 

The platinum-group metals (Ru, Os, Rh, Ir, Pd and Pt) are rare (Figure 23.1) and expensive, and occur together either native or in sulfide ores of Cu and Ni. Three sites of mineral deposits in the former Soviet Union, Canada and South Africa hold the world s reserves. The main source of ruthenium is from wastes from Ni refining, e.g. from pentlandite, (Fe,Ni)S. Osmium and iridium occur in osmiridium, a native alloy with variable composition 15-40% osmium and 80-50% iridium. Rhodium occurs in native platinum and in pyrrhotite ores (Fei S, n = 0-0.2, often with <5% Ni). Native platinum is of variable composition but may contain as much as 86% Pt, other... 

The platinum group metals (Ru, Rh, Pd, Os, Ir, and Pt), Ag, and Au are called precious or noble metals. Nobility and catalytic activity are unique properties of precious metals, that result in a wide range of applications, such as catalysts in various industrial fields, in electronic industries, and in jewelry. The chemical and physical properties of each precious metal are shown in Table 1. The determination of precious metals attracted the interest of analysts and developed rapidly because these metals are valuable and rare, and also very important for many products. Their concentration levels are very low in many natural sources, metallurgical intermediates, and environmental samples. Furthermore, precious metals are collectively handled in the analytical chemistry field, because of the close resemblance of their chemical properties and behavior. Precious metals are the subproducts in copper, zinc, or lead smelting and refining, which is the most important source of precious metals. Whereas many analytical methods for the ultratrace determination of precious metals in environmental or biological samples were recently published with the development of high-sensitivity analytical instruments, the classical fire-assay has been widely applied for the accurate determination of expensive precious metals. 

Piana M, Boccia M, Filpi A, Flammia E, Miller HA, Orsini M, Salusti F, Santiccioli S, Ciardelli F, Pucci A (2010) H2/air alkaline membrane fuel cell performance and durability, using novel ionomer and non-platinum group metal cathode catalyst. J Power Sources 195(18) 5875-5881... 

With the exception of gold and the platinum-group metals (Ru, Rh, Pd, Os, Ir, and Pt), most metallic elements are found in nature in solid inorganic compounds called minerals. Table 23.1 lists the principal mineral sources of several common metals, three of which are shown in Figure 23.2 . Notice that minerals are identified by common names rather tlian by chemical names. Names of minerals are usually based on the locations where they were discovered, the person who discovered them, or some characteristic such as color. The name inalachite, for example, comes from the Greek word malache, the name of a type of tree whose leaves are the color of the mineral. 

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