Introduction to Platinum
Platinum, a member of the platinum group metals (PGMs), is a dense, malleable, ductile, highly unreactive, precious, silver-white transition metal. Its name is derived from the Spanish word “platina,” meaning “little silver.” This element is renowned for its excellent corrosion resistance, high melting point, and catalytic properties, making it indispensable in various high-technology applications.
Everyday Applications of Platinum
Platinum’s unique properties translate into several critical uses across various sectors.
Jewellery
Platinum is highly valued in the jewellery industry due to its natural white lustre, durability, and resistance to tarnishing. Its purity (often 95% pure) makes it a popular choice for rings, necklaces, and other ornaments, particularly for wedding and engagement jewellery in India, where it signifies enduring love and rarity.
Catalytic Converters
One of the most significant industrial uses of platinum is in catalytic converters for vehicles. These devices convert harmful pollutants in exhaust gases (such as carbon monoxide, nitrogen oxides, and unburnt hydrocarbons) into less noxious substances (like carbon dioxide, nitrogen, and water vapour). All vehicles manufactured and sold in India adhere to strict emission norms (e.g., Bharat Stage standards), which necessitate the use of catalytic converters containing platinum, along with palladium and rhodium.
Laboratory Equipment
In scientific research and industrial laboratories, platinum is extensively used for manufacturing crucibles, electrodes, and other high-temperature apparatus. Its inertness to many chemical reagents, high melting point (1768.3 °C), and consistent electrical properties make it ideal for applications requiring chemical resistance and stability, such as high-temperature experiments and electrochemistry. Many educational and research institutions across India utilize platinum laboratory ware.
Medical Implants and Devices
Platinum’s biocompatibility, meaning it is non-toxic and does not react adversely with body tissues, makes it a preferred material for various medical devices. It is used in pacemakers, defibrillators, dental fillings (though less common now), and some chemotherapy drugs (e.g., cisplatin) that contain platinum compounds. Stents used to open narrowed arteries can also incorporate platinum components.
Electrical and Electronic Components
Due to its excellent electrical conductivity and resistance to corrosion and oxidation, platinum finds use in electrical contacts, resistance thermometers, and thermocouples. It is also a component in some high-performance spark plugs, hard disk drives, and fibre optic cables. Its reliability is crucial in precision electronic applications.
Natural Occurrence and Extraction
Global Distribution
Platinum is a relatively rare element in Earth’s crust. It is primarily found as a native metal, often alloyed with other platinum group metals like palladium, osmium, iridium, and rhodium. Significant commercial deposits are found in mafic and ultramafic igneous rocks. The world’s largest platinum reserves are located in South Africa (e.g., Bushveld Igneous Complex), followed by Russia (Norilsk-Talnakh deposits), Zimbabwe, and Canada.
Mining and Refining Processes
The extraction of platinum is a complex and multi-stage process. Platinum-bearing ores, which may include minerals like sperrylite (PtAs2) and cooperite (PtS), are typically mined from underground deposits.
- Mining: Ore is extracted from the earth, often through deep shaft mining.
- Milling and Flotation: The ore is crushed and ground into a fine powder. This powder is then mixed with water and reagents in a flotation cell, where air bubbles selectively attach to the platinum group metal particles, causing them to float to the surface as a concentrate.
- Smelting and Converting: The concentrate undergoes high-temperature smelting to remove impurities and separate base metals, resulting in a matte. This matte is then further refined in converters.
- Hydrometallurgical Refining: The matte is dissolved in acidic solutions, and various chemical precipitation and solvent extraction techniques are employed to separate platinum from other platinum group metals and base metals. This highly specialized process results in platinum of high purity.
Platinum in the Indian Context
India possesses very limited known reserves of platinum group metals, with minor occurrences reported in regions like Odisha (e.g., Boula-Nuasahi chromite belt). Consequently, India is heavily reliant on imports for its platinum requirements. The demand for platinum in India is largely driven by its flourishing jewellery market, increasing adoption of catalytic converters in the automotive sector, and growing pharmaceutical and chemical industries that utilize platinum catalysts. The country imports refined platinum, primarily from major producing nations or through global commodity markets, to meet its industrial and consumer needs.