In modern society, the purification of Platinum Group Metals (PGMs) is an important mineral processing task, with numerous techniques developed over the years in order to increase purity levels of these metals. PGMs, including osmium, iridium, palladium and platinum, are found in large deposits throughout the world and are widely used in industry and in jewellery. Although they may be present in the raw ore in very small amounts, they are considered to be valuable and are worth refining in order to increase their purity.
Separation techniques for all four elements involve a great deal of chemistry, as each metal has its own unique properties. In general, the separation of PGMs involves the use of a chemical solution and a method of electrolysis. Osmium is easily extracted from its ore due to its high melting and boiling point, making it a good candidate for extraction. This can be done by passing an electric current through a molten solution.
Iridium and palladium can be extracted using the same technique, but their extraction requires slightly more energy due to their lower melting and boiling points. Nevertheless, the principle remains the same - passing an electric current through a molten solution of these metals to produce a separation. In addition to electrolysis, separation methods such as solvent extraction, chromatography, melt crystallisation and distillation can be used to isolate these metals.
Finally, the most difficult step in PGM extraction is with platinum, largely due to its high melting point. Complete separation of this metal can be quite difficult, requiring multiple separations. The process of separating platinum is quite complex, involving multiple steps including dissolution, acid leaching, and precipitation. Platinum can also be separated from other metals through the use of a solvent-exclusion process, which involves passing a solvent through a pad of powder and allowing it to pick up platinum, while leaving other elements behind.
In conclusion, separation of Platinum Group Metals can be difficult, however, there are many different techniques available to help in this process depending on the nature of the ore and the exact elements being separated. Using the right separation technique can ensure that metals are purified to a high standard and extracted in the most efficient manner.
