Introduction
Platinum group metal (PGM) enrichment is a process used to separate metal and metal compounds from other materials. This process is used to produce concentrate from ore that may be too low in PGM content to be of commercial value. PGMs are a group of six metals containing platinum, palladium, rhodium, osmium, iridium and ruthenium. These metals are valuable due to their physical and chemical properties, making them valuable in many industrial processes.
Enrichment of PGM involves a number of methods. Two of the most common are chemical precipitation and flotation. Flotation is a process of separating dissolved minerals by passing them through an adjuvant solution. The adjuvant solution consists of salts of calcium, sodium, potassium and other cations in a water solution. During flotation, hydrophobic PGM elements are bound to the anionic surface of the adjuvant solution and become flighted. The flighted PGM elements are then separated from the solution by using a separator device.
Chemical precipitation is another method of PGM enrichment. This process involves adding a reagent to the PGM containing solution that forms a precipitate containing the PGM. The most commonly used reagent is ammonium sulfate. The precipitated PGM elements are then separated from the solution by filtration.
Another method for enriching for PGM is smelting. Smelting is the process of heating a mixture of ore and flux to high temperatures to separate the metals and other valuable constituents. The smelted material is then poured into a mould to create an alloy containing the desired PGM.
A fourth method of PGM enrichment is electrorefining. This process involves passing an anode in solution through a copper U-tube filled with an electrolyte. This electrolyte consists of acid and base salts. The anode contains the desired PGM and is oxidized by the electrolyte. The PGM is then separated from the other elements present in the solution and deposited onto the cathode.
Lastly, leaching can be used for PGMs enrichment. Leaching is the process of dissolving a material in a liquid solvent. The PGM is dissolved in the solvent and precipitated out of the solution in the form of a concentrated solid.
Conclusion
Enrichment of PGM is an important way of separating PGMs from other materials and recovering them in a higher concentration. The five main methods used for PGM enrichment are flotation, smelting, electrorefining, leaching and chemical precipitation. Each method has its own specific pros and cons that must be considered when deciding which method is most appropriate for a given application. Depending on the specific needs of the application, the best method for PGM enrichment should be chosen.
