Platinum Group Metals

Platinum Group Metals are commonly found in asteroids and may possibly be found in lunar impact craters.

The platinum-group metals (PGM) comprise six closely related metals: platinum, palladium, rhodium, ruthenium, iridium, and osmium, which commonly occur together in nature and are among the scarcest of the metallic elements. Along with gold and silver, they are known as precious or noble metals. They occur as native alloys in placer deposits or, more commonly, in lode deposits associated with nickel and copper. Nearly all of the world's supply of these metals are extracted from lode deposits in four countries--the Republic of South Africa, the U.S.S.R., Canada, and the United States. The Republic of South Africa is the only country that produces all six PGM in substantial quantities. - USGS Platinum-Group Metals Statistical Compendium[1]

Applications

The catalytic properties of the six platinum group metals (PGM)– iridium, osmium, palladium, platinum, rhodium, and ruthenium – are outstanding. Platinum's wear and tarnish resistance characteristics are well suited for making fine jewelry. Other distinctive properties include resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum, platinum alloys, and iridium are used as crucible materials for the growth of single crystals, especially oxides. The chemical industry uses a significant amount of either platinum or a platinum-rhodium alloy catalyst in the form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for fertilizers, explosives, and nitric acid. In recent years, a number of PGM have become important as catalysts in synthetic organic chemistry. Ruthenium dioxide is used as coatings on dimensionally stable titanium anodes used in the production of chlorine and caustic. Platinum supported catalysts are used in the refining of crude oil, reforming, and other processes used in the production of high-octane gasoline and aromatic compounds for the petrochemical industry. Since 1979, the automotive industry has emerged as the principal consumer of PGM. Palladium, platinum, and rhodium have been used as oxidation catalyst in catalytic converters to treat automobile exhaust emissions. A wide range of PGM alloy compositions is used in low-voltage and low-energy contacts, thick- and thin-film circuits, thermocouples and furnace components, and electrodes. - USGS Platinum-Group Metals Statistics and Information[2]

Iridium

Atomic symbol:	Ir
Atomic number:	77
Group:	9
Period:	6
Series:	Transition Metals

Natural Isotopes

• Iridium 191
• Iridium 193

Osmium

Atomic symbol:	Os
Atomic number:	76
Group:	8
Period:	6
Series:	Transition Metals

Natural Isotopes

• Osmium 184
• Osmium 186
• Osmium 187
• Osmium 188
• Osmium 189
• Osmium 190
• Osmium 192

Palladium

Atomic symbol:	Pd
Atomic number:	46
Group:	10
Period:	5
Series:	Transition Metals

Natural Isotopes

• Palladium 102
• Palladium 104
• Palladium 105
• Palladium 106
• Palladium 108
• Palladium 110

Platinum

Atomic symbol:	Pt
Atomic number:	78
Group:	10
Period:	6
Series:	Transition Metals

Natural Isotopes

• Platinum 190
• Platinum 192
• Platinum 194
• Platinum 195
• Platinum 196
• Platinum 198

General Information
Platinum is a beautiful silvery-white metal, when pure, and is malleable and ductile. It has a coefficient of expansion almost equal to that of soda-lime-silica glass, and has been used to make sealed-in electrodes in glass apparatus. The metal does not oxidize appreciably in air at any temperature, but is corroded by halogens, cyanides, sulphur, and caustic alkalis. It is insoluble in hydrochloric and nitric acids, but dissolves when they are mixed to form aqua regia, forming chloroplatinic acid, an important compound.
The metal is extensively used in jewellery, wire, and vessels for laboratory use, and in many valuable industrial products including thermocouples. It is also used for electrical contacts, corrosion-resistant apparatus, and in dentistry. Platinum-cobalt alloys have powerful magnetic properties. One such alloy made of 76.7% Pt and 23.3% Co, by weight, offers a B-H (max) almost twice that of Alnico V. Platinum resistance wires are used for constructing high-temperature electric furnaces. The metal is used for coating missile nose cones, jet engine fuel nozzles, gas-turbine blades, etc., which must perform reliably for long periods of time at high temperatures under oxidising conditions. The metal, somewhat like palladium, absorbs hydrogen, retaining it at ordinary temperatures but giving it up at red heat.
In the finely divided state, platinum is an excellent catalyst, having long been used in the contact process for producing sulphuric acid. It is also used as a catalyst in cracking petroleum products. There is much current interest in the use of platinum as a catalyst in fuel cells and in antipollution devices for automobiles. Platinum clad anodes are extensively used in cathodic anti-corrosion protection systems for large ships and ocean-going vessels, pipelines, steel piers, etc.
The price of platinum has varied widely; more than a century ago it was cheap enough to be used to adulterate gold. It was nearly eight times as valuable as gold in 1920. The price in December 1987 was about $520/troy oz.
PGM Database[3]

Rhodium

Atomic symbol:	Rh
Atomic number:	45
Group:	9
Period:	5
Series:	Transition Metals

Natural Isotopes

• Rhodium 103

Ruthenium

Atomic symbol:	Ru
Atomic number:	44
Group:	8
Period:	5
Series:	Transition Metals

Natural Isotopes

• Ruthenium 96
• Ruthenium 98
• Ruthenium 99
• Ruthenium 100
• Ruthenium 101
• Ruthenium 102
• Ruthenium 104

External Links

PGM Database http://www.platinummetalsreview.com/jmpgm/index.jsp

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