Platinum, along with other platinum group metals, is commonly obtained as by-products of nickel and copper mining and processing. During the electro-refining process of copper, noble metals such as silver, gold, and those of the platinum group settle at the bottom of the cell in the form of "anode sludge", serving as a starting point for the further extraction of platinum group metals.
When pure platinum is discovered in alluvial deposits or other ores, it is isolated using various methods aimed at removing impurities. Due to its significantly higher density than many impurities, lighter elements are often removed by allowing them to float in a liquid. Heavier nickel and iron impurities are removed using an electromagnet. Since the melting point of platinum is higher than that of most other substances, many impurities are burned or melted without affecting the platinum. Finally, platinum, resistant to hydrochloric and sulfuric acids, remains unscathed, while other substances are attacked by these acids. Metallic impurities are often removed by stirring the mixture in one of these acids, thus allowing the remaining platinum to be recovered.
An effective method for purifying raw platinum, containing platinum, gold, and other platinum group metals, is to treat it with nitro-hydrochloric acid. In this process, platinum, palladium, and gold dissolve, while osmium, iridium, ruthenium, and rhodium do not react.