Platinum: properties, grades and applications / Articles

Platinum (Pt) is a noble metal of the platinum group, rightly considered one of the most valuable and strategically important materials of modern industry. It is a heavy, ductile, silvery-white metal possessing exceptional chemical inertness, high catalytic activity and the ability to retain its properties at extreme temperatures. Thanks to these qualities, platinum has become an indispensable component in the production of automotive catalytic converters, chemical catalysts, electronic components, medical devices and high-temperature technology. Global platinum consumption is measured in millions of ounces, and its market is characterised by high volatility and strategic importance for the global economy.

Chemical Nature and Physicochemical Properties

Platinum is a transition metal of the platinum group, atomic number 78, atomic mass 195.084 g/mol. The density of platinum is 21.09–21.45 g/cm³, making it one of the heaviest metals, second only to osmium and iridium in this respect. The melting point of platinum is 1768.3 °C, and the boiling point is about 3825 °C. Its electrical resistivity is 0.098 μΩ·m at 0 °C.

A key feature of platinum is its exceptional chemical resistance. The metal does not oxidise in air at any temperature, does not dissolve in hydrochloric or nitric acid, but dissolves in hot aqua regia to form chloroplatinic acid (H₂PtCl₆). Platinum is also resistant to halogens, cyanides, sulfur and caustic alkalis, although under certain conditions it can undergo corrosion. Due to this inertness, platinum retains its properties for centuries and is indispensable in aggressive environments.

Platinum has high ductility and is well suited to hot and cold deformation, rolling, drawing and welding. It has high reflectivity and low thermal and electrical conductivity compared to other noble metals. The hardness of platinum on the Mohs scale is 3.5–4.5, and on the Brinell scale — about 50 kgf/mm².

Classification, Grades and Standards

In Russia and CIS countries, requirements for refined platinum in ingots are established by GOST 12341-2014 (previously GOST 12341-81 was in force). The standard applies to refined platinum in ingots intended for the manufacture of alloys, chemicals and other purposes, and establishes requirements for chemical composition, shape and marking.

Depending on the content of the base metal and impurities, the following grades are established:

PtA-00 — the purest grade, platinum content of at least 99.98%. Used for critical electrical, catalytic and precision applications.
PtA-0 — platinum content of at least 99.98%. Used for the production of catalysts, chemicals and special alloys.
PtA-1 — platinum content of at least 99.95%. Used for various technical purposes and alloys.
PtA-2 — platinum content of at least 99.90%. Used for less critical technical needs.

For each grade, the content of impurities is standardised: palladium, iridium, rhodium, ruthenium, gold, lead, iron, silicon, tin, aluminium, antimony, silver and other elements. For example, for grade PtA-0, the sum of palladium, iridium, rhodium and ruthenium must not exceed 0.015%, gold — 0.002%, iron — 0.003%.

In addition to pure grades, the standard establishes grades of platinum alloys used to improve mechanical properties and impart specific characteristics. These include alloys with rhodium (PtRh), iridium (PtIr), ruthenium (PtRu) and others. These alloys are used in electrical engineering, catalysis and high-temperature applications.

Platinum is supplied in the form of ingots weighing up to 5.5 kg, as well as semi-finished products: sheets, foil, wire, pipes and profiles. Each batch is accompanied by a certificate with chemical analysis and mechanical characteristics.

Production Technology and Refining

Platinum is typically obtained as a by-product of processing sulfide copper-nickel ores (e.g., in the Norilsk region) and platinum-containing ores. The technological chain includes ore mining and beneficiation, pyrometallurgical processing to produce matte, extraction of precious metals into slimes and subsequent refining — a complex multi-stage purification process to high purity.

Platinum refining typically includes the following stages:

Dissolution of the platinum-containing concentrate in aqua regia to form chloroplatinic acid.
Precipitation of platinum in the form of sparingly soluble salts, such as ammonium hexachloroplatinate, using ammonium chloride.
Purification of the resulting salt from impurities (palladium, rhodium, iridium, gold) by recrystallisation or ion exchange.
Reduction of platinum to metal using formic acid, hydrogen or other reducing agents.
Washing, drying and melting of the metal platinum into ingots or producing powder.

Modern technologies allow platinum of 99.99% purity and higher to be obtained. The resulting metal is supplied in the form of ingots, granules, powder, as well as semi-finished products (sheets, foil, wire, crucibles).

Applications

Automotive catalytic converters. This is the largest area of platinum consumption — it accounts for about 40% of global demand. Platinum is used in catalytic converters to neutralise exhaust gases from gasoline and diesel engines. It promotes the oxidation of hydrocarbons and carbon monoxide (CO) to carbon dioxide and water, as well as the reduction of nitrogen oxides. Tightening environmental standards stimulate an increase in platinum content in catalysts, especially for hybrid vehicles.

Chemical industry and catalysis. Platinum is a highly effective catalyst in the production of nitric acid, silicones, benzene and other chemical products. It is used in hydrogenation, dehydrogenation, oxidation and oil cracking processes. Platinum catalysts are also used for gas purification and in fuel cells.

Electronics and electrical engineering. Platinum is used in the production of computer hard disks, thermocouples, optical fibres, liquid crystal displays and multilayer ceramic capacitors. Due to its high melting point and corrosion resistance, it is indispensable in high-temperature electronic components.

Medicine. Platinum and its compounds are used in dentistry for crowns, bridges and dentures, as well as in medical instruments and implants. Platinum compounds (e.g., cisplatin) are important chemotherapeutic drugs for treating cancer. Platinum is also used in pacemakers and other medical devices.

Glass melting and fibreglass production. Platinum and its alloys are used for the manufacture of crucibles and bushings resistant to the aggressive effects of molten glass. This is critically important for the production of fibreglass, optical glass and displays.

Hydrogen energy. Platinum is a key component of catalysts for fuel cells and electrolysers used in hydrogen energy. The development of the hydrogen economy opens up new prospects for platinum.

Other applications. Platinum is used in the jewellery industry (as an alloying additive for white gold and as a standalone metal), in watchmaking, in optics and laser technology, and in the aerospace industry for high-temperature coatings and sensors.

Safety and Storage

Platinum in massive form (ingots, semi-finished products) is non-toxic and chemically inert, so it does not present a hazard when standard precautions are observed. However, platinum dust and aerosols can cause irritation of the respiratory tract and mucous membranes. When working with powders and nanoparticles of platinum, personal protective equipment (respirators, safety goggles, gloves) must be used and effective ventilation of premises must be ensured. Platinum is non-flammable, but in a finely dispersed state it can be fire-hazardous.

Storage of platinum is carried out in closed dry premises protected from moisture and chemically active substances. Ingots and semi-finished products are stored in individual packaging that prevents mechanical damage. For precious metals, protection from unauthorised access is also important, so specialised vaults and safes are used.

Market and Trends

The global platinum market is characterised by high volatility and structural changes. In recent years, the market has been in a state of deficit: according to the World Platinum Investment Council (WPIC), the deficit has persisted for several consecutive years due to limited mine supply and growing demand from industry and investors. Total platinum supply largely depends on mining in South Africa and Russia, as well as on recycling of automotive catalysts and jewellery.

Key drivers of long-term demand remain the tightening of environmental standards for hybrid vehicles, the development of hydrogen energy, the growth of fibreglass and electronics production, and investment demand for physical platinum. The main consumers are China, Europe, North America and Japan. Producers with access to quality refined metal and modern processing technologies occupy stable positions.

Conclusion

Platinum remains a strategically important platinum group metal, supporting the operation of automotive catalysts, the chemical industry, electronics, medicine and hydrogen technologies. Understanding the grade composition according to GOST 12341-2014, refining technologies and safety requirements is the basis for competent material selection and the organisation of efficient supplies. Selecting the platinum grade for specific technological tasks and organising logistics requires an individual approach taking into account metal purity, delivery form and market conditions.