Platinum

Platinum is a chemical element with atomic number 78, located in group 10 of the periodic table of elements. Its symbol is Pt. It is a grayish-white, precious, heavy, malleable and ductile transition metal. It is resistant to corrosion and is found in different minerals, frequently together with nickel and copper; it can also be found as a metal. It is used in jewelry, laboratory equipment, electrical contacts, fillings, and automobile catalysts.

History

First uses

Archaeologists have discovered traces of platinum in gold used in ancient Egyptian burials as early as 1200 B.C. For example, a small burial box from Shepenupet II was found to be decorated with gold and platinum hieroglyphics. However, the extent of early Egyptian knowledge of the metal is unclear, as it is very they may not have recognized that there was platinum in their gold.

The metal was used by pre-Columbian Americans near present-day Esmeraldas (Ecuador) to produce artifacts from an alloy of white gold and platinum. Archaeologists often associate the tradition of working with platinum in South America with the La Tolita culture (circa 600 BC-AD 200), but precise dates and locations are hard to come by, as most of the platinum artifacts in the area were purchased secondhand through the antiquities trade rather than being obtained by direct excavation. To work the metal, gold and platinum powders were combined by sintering. The resulting alloy of gold and platinum would be soft enough to be molded with tools. The platinum used in such objects was not the pure element, but a natural mixture of the platinum group metals, with trace amounts of palladium, rhodium, and iridium.

European discovery

The first written reference appears in the XVIII century, in the work of the Spanish Antonio de Ulloa, Relation Histórica del Viaje a la América Meridional, published in 1748. This work indicates that it was found in the gold pans of Chocó (Colombia), and that it was impossible to melt it with the means available at the time.. The name of the element refers to the fact that its color is similar to that of silver. Platinum was used for the production of some goldsmith pieces in the Tolita culture, in pre-Columbian Ecuador. Detailed study of the properties of this element was carried out by English chemists, notably William Watson, William Brownrigg and William Lewis. French chemists 1758, Pierre Joseph Macquer and Antoine Baumé demonstrated that it could be fused, using a large concave mirror that concentrated the heat in the focus Its purification until making it malleable was achieved in 1783 by Pierre-François Chabaneau, a French chemist working for the Spanish Crown. In 1822, platinum was also found in the Ural Mountains (Russia), and later in Canada and South Africa.

Uses and applications

Platinum is used in many essential applications, while new uses for platinum are constantly being developed.

• Jewelry: It was very fashionable in the 1930s and 1940s in art-deco jewelry. In 2006, the demand for platinum for jewellery represented 25% of the total demand for platinum. This precious metal is highly valued for its beauty and purity, along with its particular properties, in Europe and the United States its normal purity is 95% although in other countries it can decay up to 85%.
  • Decoration: In the music industry, it is common for associations and/or record labels to deliver "Platin Discs" for reaching specific sales figures from an album or simple, almost always consisting of a plate embedded with a platinum-plated vinyl disc.

• Vehicle catalysts: Platinum, along with palate and rodium, are the main components of catalysts that reduce emissions of gases such as hydrocarbons, carbon monoxide or nitrogen oxide in vehicles. Catalysts convert most of these emissions into carbon dioxide, nitrogen and water vapor, which are less harmful. This is the second sector with the highest use of platinum, reaching 51% of the total demand for platinum in 2006.

• Electrical and electronic: Platinum is used in the production of hard drives on computers and fiber optic cables. The increasing use of personal computers will continue to have a very positive effect on the demand for platinum in the future. Other platinum applications include devices (termopares and thermoistors) that measure temperature in glass, steel and semiconductor industries, or infrared detectors for military and commercial applications. It is also used in multi-layer ceramic capacitors and in glass crucibles.

• Chemistry: Platinum is used in fertilizers and explosives as a gauze for the catalytic conversion of ammonia into nitric acid. It is also used in the manufacture of silicone for aerospace, automotive and construction sectors. In the petrol sector it is used as fuel additive to boost combustion and reduce engine emissions. In addition, it is a catalyst in the production of biodegradable elements for domestic detergents.

• Glass: Platinum is used in glass manufacturing equipment. It is also used in the production of plastic reinforced with fiberglass and in liquid glass devices.

• Oil: Platinum is used as a refined catalyst in the oil industry.

• Medical uses: Platinum is used in anti-cancer drugs and implants. It is also used in neurosurgery and alloys for dental restorations.

• Bujías: Most vehicles in North America use spark plugs with platinum filter. In Europe, the highest durability requirements have led to an increase in the number of platinum used in spark plugs.

• New applications: fuel batteries are devices that generate electricity and are currently being developed as an alternative to internal combustion engines in vehicles. Most of these devices apply proton-exchange membrane technologies to produce energy from hydrogen and oxygen, using platinum catalysts. The use of fuel batteries has both environmental and economic advantages. They are more efficient in energy production and pollution is minimal.

Main features

When pure, it is greyish-white, malleable and ductile. It is resistant to corrosion and does not dissolve in most acids, although it is possible to dissolve it using aqua regia, resulting in chloroplatinic acid. It is slowly attacked by hydrochloric acid (HCl) in the presence of air. The elements ruthenium, osmium, rhodium, iridium, palladium, and platinum are called the platinum group. These elements are widely used as catalysts.

Platinum is relatively resistant to chemical attack, has good physical properties at high temperatures, and also good electrical properties. This has led to its use in different industrial applications. For example, it can be used as an electrode, in electronic contacts, etc. Platinum does not oxidize in air, but it can react, depending on conditions, with cyanides, halogens, sulfur, lead, silicon, and other elements, as well as some molten basic oxides and ozone.

Production

A native platinum nuggets (dimensions: ca. 35×23×14 mm; weight: ca. 112 g) of a Kondër massif mine in the Khabárovsk krai, Russia.

Today, South Africa has the largest platinum reserves in the world (more than 70% of the world total), making it its largest producer and exporter. Russia and Canada have modest reserves of this metal, and the United States has minimal production despite its deposits (almost half of the Canadian deposits). Between South Africa and Russia alone, 90% of the world's platinum production is generated.

Location

It is found in igneous rock mines in very small granules. The world production of platinum, estimated at around 16 tons per year, is distributed mainly between Colombia, the United States, South Africa, Canada and the countries of the former USSR.

Normally it is found in a metallic state alloyed with other metals of its group in the form of nuggets and flakes and mainly associated with nickel, copper and chromium minerals.

A nugget of about 9.5 kg has been found with almost 80% richness in platinum and the rest distributed in metals such as iridium, palladium, rhodium, osmium, ruthenium, gold, etc.

In nature, it is generally part of the Platinum Group Metals and is found together with other metals such as gold, nickel or copper. The Platinum Group Metals (PMG) are Platinum (Pt), Palladium (Pd), Rhodium (Rh), Ruthenium (Ru), Iridium (Ir) and Osmium (Os). Platinum and Palladium are the most important of the group.

Location

Figures taken in 2003, includes metals contained in ores and concentrates, source: L'état du monde 2005

Precautions

Platinum as a metal is not very dangerous, but its salts can cause various effects such as:

• Combustiones
• DNA alteration
• Cancer
• Allergic reactions with mucous and skin
• Damage to organs such as the intestine, kidneys and spinal cord
• Hearing damage

Finally, a danger of platinum is that it can cause the potentiation of toxicity of other dangerous chemicals in the human body, such as selenium.