What is Platinum?

Platinum is one of earth’s rarest metals.   It belongs to a group of metals known as Platinum Group of metals (PGMs), which consists of six elements – platinum, palladium, rhodium, iridium, ruthenium, osmium; and is associated with the following base metals, nickel, copper and cobalt. Platinum, palladium and rhodium, the most economically significant of the PGMs, are found in the largest quantities. The remaining PGMs are produced as co-products.

 

Platinum

 

Platinum, a silvery-white metal and the most common and widely used of the platinum group metals (PGMs), is also one of the most precious metals. As with all of the PGMs but especially so in its case, platinum has many unique properties making it ideally suited to advanced technical applications.

As one of the densest and heaviest metals known to man, platinum is also extremely durable. It is also very malleable and ductile. Although it has a very high melting point (1,772°C), it is stable at extremely high temperatures. In addition to being resistant to corrosion and chemical attack, it is a very good conductor of electricity, is a powerful catalyzing agent and is recyclable. Platinum is primarily used in the jewellery and automotive industries, with the latter making use of its excellent catalytic properties.

 

Palladium

 

Palladium, together with platinum, is more abundant than any of the other PGMs. Like its sister metal, platinum, palladium has a natural white lustre when polished. It is the lightest and has the lowest melting point (1,554°C) of all the PGMs. Its most remarkable property is its ability to absorb enormous amounts of hydrogen at room temperature.

During this process the metal expands and becomes harder, stronger and less ductile, thus making it an efficient and safe medium for the storage of hydrogen and as a purifier. Given palladium's catalytic qualities, it too has a vital role in catalytic converters and in air purification equipment. Its chemical stability and excellent electrical conductivity make it a more effective and durable plating than gold in electronic components. It is most frequently used in alloys or as a catalyst and can be used as a substitute for platinum in jewellery, electrical contacts and catalysts.

 

Rhodium

 

Rhodium is also a silvery-white metal but has a higher melting point and lower density than platinum. It has a high reflectance and is hard and durable, and is a major component of industrial catalytic systems. Its primary use is in the automotive industry for the reduction of NOx to nitrogen.

Rhodium alloyed with other PGMs is used for furnace windings, thermocouple elements, bushings for glass fibre production, electrodes for aircraft spark plugs and laboratory crucibles. Rhodium is useful as an electrical contact material as it has a low electrical resistance, a low and stable contact resistance and is highly resistant to corrosion.

 

Nickel

 

Nickel, an important by-product of PGM mining operations, is a hard, silvery-white metal that is highly resistant to corrosion.

It is used extensively in coins and is a vital ingredient in the production of stainless steel. The stainless steel industry consumes approximately two thirds of nickel supply with the balance being used either in alloys or for electroplating.

 

Iridium

 

Iridium is a hard, brittle and lustrous platinum group metal (PGM) that is very stable at high temperatures as well as in chemical environments. Pure iridium metal is an extremely stable and dense transition metal.

Iridium is considered the most corrosion resistant pure metal because of its resistance to attack from salts, oxides, mineral acids and aqua regia (a mixture of hydric and nitrochloric acids), while only being vulnerable to attack by molten salts such as sodium chloride and sodium cyanide. Metallic iridium has the second highest modulus of elasticity of all metal elements, meaning that it is very stiff and resistant to deformation, characteristics that make it difficult to fabricate into usable parts but which make it a valuable alloy-strengthening additive. Platinum, when alloyed with 50% iridium, for example, is nearly ten times harder than when in it's pure state.

 

Ruthenium

 

Ruthenium is a brittle and rare platinum group metal (PGM) that is widely used in the electronics industry due to its conductive properties and durability. Pure ruthenium is a hard, dense, silvery-white metal that, like other platinum group metals, has a high melting point and good catalytic properties. It has a high electrical conductivity, is resistant to corrosion and stable under a wide-range of conditions.

The metal does not tarnish at room temperature and only begins to oxidize at about 1472°F (800°C). Ruthenium metal is inert and unaffected by strong acids, but can be dissolved in molten alkalis. Being very brittle, ruthenium cannot be easily cast or made into wires. But is effective as an alloying agent to harden palladium, platinum and other metals.

 

 

Osmium

 

Osmium is the least abundant stable element in Earth's crust with an average mass fraction of 50 parts per trillion in the continental crust.  Osmium is found in nature as an uncombined element or in natural alloys; especially the iridium–osmium alloys, osmiridium (osmium rich), and iridosmium (iridium rich). Osmium is obtained commercially as a by-product from nickel and copper mining and processing. During electro refining of copper and nickel, noble metals such as silver, gold and the platinum group metals, together with non-metallic elements such as selenium and tellurium settle to the bottom of the cell as anode mud, which forms the starting material for their extraction. Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility. Correspondingly, its bulk modulus is extremely high, reported between 395 and 462 GPa, which rivals that of diamond (443 GPa). The hardness of osmium is moderately high at 4 GPa.[5][6][7] Because of its hardness, brittleness, low vapor pressure (the lowest of the platinum group metals), and very high melting point (the fourth highest of all elements), solid osmium is difficult to machine, form, or work.