Recovery of Platinum Group Metals from Scrap Alloy
The recovery of platinum group metals (PGMs) from scrap metals has become an increasingly valuable enterprise in recent years, as the value of the PGMs has risen dramatically. Platinum itself is the most sought-after PGM, but other metals in the group - palladium, rhodium, ruthenium, osmium, and iridium - are also in demand. Such metals are used in products ranging from catalytic converters and medical supplies to jewelry, and their scarcity means that demand – and price – for these metals is relatively high. As such, the recovery of these metals from scrap alloys has become an important and profitable business.
The process of recovering these precious metals from scrap alloy is complex and can involve many steps. It begins with the identification of alloys that contain PGMs, followed by the selection of the most efficient method by which to extract the needed metals. This process may include a combination of melting, dissolving, distilling and other techniques. In the latter cases, the PGMs are purified through several steps, and the final result is the recovery of pure PGMs.
For most scrap alloys, the melting method is the most efficient route. This method entails heating a mixture of scrap alloy and reducing flux to a liquid state and then skimming off the molten metals as they float to the surface. The metals that float to the top must then be further refined to separate the various tasks. This is usually done with an electrolytic process, in which an electric current is passed through the solution to separate the metals. The PGM sheet scrap, which includes coated items, can also be electrochemically melted and joined to the PGMs at the rate of about 1 kg of scrap per 100 kg of PGMs. The metals separated by this process are then cast into bars and can be melted together to produce pure PGMs.
Another method used for extracting PGMs from scrap alloys is solvent extraction. This process requires the use of a solvent capable of dissolving the desired metals in a certain concentration. Once extracted, the solvent containing the dissolved metals is treated with a reagent that precipitates the metals, allowing them to be separated. The remaining liquid is then separated from the precipitated metals, usually through centrifuging. The recovered metals are then processed further to remove impurities and refine the final product.
These are just a few of the methods used in extracting platinum group metals from scrap alloys. Depending on the type of alloy and the desired end product, a variety of techniques can be used to separate the PGMs from other materials. The right choice of method can substantially improve the efficiency of recovering the valuable metals, thereby increasing a company’s profits.
