The Platinum Group Metals (PGM) are located in the 5th and 6th rows of the transition metal section of the periodic table. Common characteristics include resistance to wear, oxidation, and corrosion, high melting points, and oxidation states of +2 to +4. They are generally non-toxic. For our purposes, Osmium will not be included in our discussion.
- 1 Uses of Platinum-Group Elements
- 2 The Global Impact of New Technologies in Platinum-Group Chemistry
- 3 Sources of Platinum Group Metal
- 4 Forms of Platinum Group Metals
- 5 Platinum Group Metal Mining and Refining Process
- 6 Supply and Demand
- 7 Future Outcomes
- 8 Sources
Uses of Platinum-Group Elements
With the advent of cheaper materials, many uses of platinum-group elements have disappeared from the modern world. However, they still play a vital role in the chemical world as catalysts, and in the industrial world as corrosive-resistant materials. Notably, the role of platinum in catalytic converters for conventional gasoline engines is one of the most important catalytic reactions in the world today.
- Platinum has a very high melting point, so it is often used to make containers to hold molten substances.
- Jewelers use platinum as plating and decoration because of its high ductibility.
- 80-90% of platinum uses are in the industrial or metellurgical industries.
- Platinum is a catalyst in the oxidation of ammonia (to nitric oxide) in the creation of nitric acid, which is a major ingredient in fertilizers.
- An estimated 200,000 ounces of gauze consisting of 90% platinum and 10% rhodium is used in the oxidation of ammonia for the production of nitric acid.
- Regarding pollution control, platinum works as a great oxidation catalyst for removing harmful chemicals in wire enamelling, abattoirs, meat and fish processing, and in nitric oxides released in hydrocarbon reactions.
- Platinised-anodes are used in the production of elemental chlorine.
- Serves as the substitute catalysis for platinum in catalytic converters.
- The primary catalyst for liquid-phase hydrogenation.
- In the late 1960's, 60% of all palladium production is used in the telephone industry in the form of cross-over contacts in telephone lines. Since the shift to a fully-electronic system, palladium use has declined.
- With the possible dawn of an alternate technology in motorized vehicles, palladium has garnered a lot of attention as a possible player in fuel cell technology.
- As the price and scarcity of platinum increases, palladium has become more marketable as the primary catalyst in combustion engines.
- The most effective homogeneous catalyst for hydrogenation, hydroformylation, and carbonylation.
- Rhodium-platinum spineretts are used as catalysts in the production of viscose and rayon. It is a soft man-made fiber commonly used in dresses, linings, shirts, shorts, coats, jackets, and other outer wear. Viscose-rayon is also used in industrial yarns (tyre cord), upholstery and carpets.
- Because of its "noble metal" status, rhodium is used in many light-duty contact applications, such as sliprings. In such cases it is coated onto the ring through electroplating
- Iridium-platinum anodes are used for the production of chlorates.
- 37% of iridium production is for electronics.
- 11% is for the coated tips of spark plugs.
- 15% is for chemical catalysis.
- Iridium is the most corrosive-resistant element known.
- Ruthenium, though having few practical applications, has been used as a cheaper alternative to gold in electronic applications.
The Global Impact of New Technologies in Platinum-Group Chemistry
The majority of all platinum-group metals are mined in the resource-rich country of South Africa. The last decade has seen major growth in the South African sector of mines known as the Bushveld Complex. Along with increased mining, documentation of sustainability by mining corporations has also increased. The very notion of mining as sustainable has been classified as an oxymoron by some scientists. Metals such as the platinum-group elements are by definition non-renewable. Thus, there are only techniques which can extend the life of the platinum-group metals, and new technologies can open up new avenues for such pursuits. Fortunately, there are also methods for preserving the metals we have already extracted. For instance, in industrial production, it is in the industries best interests to reuse as many materials as possible. In th case of platinum and palladium catalytic converter production, preservation of platinum can reach 97%, making the need for additional platinum negligible.
Sources of Platinum Group Metal
Platinum group metals (PGM) are found in various areas. Some of the major PGM production nations are South Africa, Western Australia, USA, Canada, Zimbabwe, China, and Russia. Of these nations, South Africa is responsible for ~72% of world Platinum production.
Forms of Platinum Group Metals
PGM deposit can be divided into two major categories: PGM dominant deposit and Nickel-copper sulphide deposits. PGM dominant deposit, as name suggests, is primarily composed of PGM with nickel and copper as less valuable byproduct. Nickel-copper sulphide, on the other hand, is sulphide-rich ores and PGM is considered byproduct.
Platinum Group Metal Mining and Refining Process
PGM ores are mined through two methods. Old method consists of drilling holes, loading them with explosives, blasting ores, and gathering the PGM ores. Newer method involves specialized drilling equipment that removes ores and transports them from the mine. Both methods are used according to the situation.
Once ore is mined, it is crushed and separated through flotation separation method (bubbling air particle through an aeration tank to allow pgm particles to adhere and float them to the top of the tank). Once PGM particles form foam at the top of the tank, they are skimmed off for refining.
Before refining process, PGM is dried under high temperature to remove unwanted materials. Byproducts are oxidized and removed, and PGM is treated with air for the further concentration.
Once concentrated, PGM goes through refining process. Eletrolytic technique is used to remove copper, cobal and nickel from PGM. Then, series of ion-exchange technique, distillation, and solvent extraction is done to purify PGM. Lastly, soluble metals are dissolved in hydrochloric acid and chlorine gas to create pure PGM.
Supply and Demand
Platinum is a very scarce resource with only about 200 metric tons produced each year, which equates to only about 10 cubic meters. Its main source of demand, catalytic converters for automobiles, has increased in recent years as a result of developing countries rapidly increasing automobile production levels. In addition, as cities become more environmentally conscious, new automobile standards are passed that require the use of higher quality catalytic converters that require more platinum. Efforts have been made into replacing platinum in catalytic converters with other metals, but the only other metals that can be used are of the platinum group, and these metals also have very limited availability.
Meanwhile, platinum supply has decreased in recent years due to labor conflicts and other difficulties in South Africa, the source of about 80% of platinum production. This drop in supply has already caused 10% hike in platinum prices in 2013. It is unlikely that more significant sources of this precious metal will be found besides the current major suppliers.
Future explorations into hydrogen fuel cells as an alternative source of power for automobiles will be limited by declining production of platinum. Fuel-cell powered cars require catalytic converters that use much more platinum than gasoline-powered ones. As efforts are made to reduce the amount of platinum in fuel cell catalytic converters, even the most hopeful calculations project these converters will require ten times as much platinum per hydrogen-powered car.