Rhodium is a rare, silvery-white metallic element. It is exceptionally hard, durable, and highly resistant to corrosion, even at elevated temperatures. As a member of the platinum group metals, rhodium possesses unique properties that contribute to its high value. This scarce element is one of the most expensive precious metals, often surpassing the price of gold or platinum.
Global Mining Locations
Rhodium is rarely found in concentrated deposits, so it is not typically mined as a primary metal. Instead, it is predominantly extracted as a byproduct during the mining of other platinum group metals, such as platinum and palladium, and sometimes from nickel and copper ores.
The largest portion of the world’s rhodium supply, approximately 80%, originates from South Africa, primarily from the Bushveld Complex, known for its extensive platinum group metal reserves. Russia is the second-largest producer, contributing around 12% to the global supply, with deposits in regions like Norilsk. North American countries, including Canada and the United States, also produce rhodium as a byproduct. Examples include the Sudbury Basin in Canada and the Stillwater Complex in Montana, USA.
Everyday Applications
Rhodium’s most prominent application, consuming between 75% and 85% of its global production, is in the automotive industry. It is a key component in catalytic converters, which reduce harmful emissions from vehicle exhausts. Rhodium specifically converts nitrogen oxides into less harmful nitrogen and oxygen gases. Its high melting point and chemical stability allow it to perform effectively in the extreme temperatures and reactive environment of exhaust systems.
Beyond emissions control, rhodium is extensively used in the jewelry sector. It serves as a plating material for white gold and sterling silver, imparting a bright, reflective, and tarnish-resistant finish that enhances aesthetic appeal and durability. Rhodium also finds application in electrical contacts due to its low electrical resistance and consistent contact performance. Other uses include specialized industrial catalysts, high-reflectivity mirrors, and crucibles in the glass manufacturing industry.
Recycling and Recovery
Given rhodium’s scarcity and high market value, recycling plays a significant role in its overall supply. Approximately one-third of the rhodium supplied globally each year is recovered through recycling efforts. The primary source for this recovered rhodium comes from end-of-life automotive catalytic converters.
The recovery process begins with collecting and dismantling used catalytic converters to access the ceramic or metallic substrate coated with precious metals. This substrate is then crushed into a fine powder, undergoing complex metallurgical treatments. These treatments often involve high-temperature processes and chemical leaching to separate and purify rhodium. Rhodium’s chemical inertness means its dissolution requires specific, multi-stage chemical processes. Recycling these materials reduces the need for new mining, offering a more sustainable approach to meeting demand.