Our refining process involves four key steps:
Evaluation
Evaluation is a critical stage. During this step we determine the PGM content of the material and agree with the customer on the PGM quantity or value we will return to them. At this stage we provide the lead time for refining. Material tracking is crucial; on receipt all customer batches are uniquely barcoded to ensure full traceability during evaluation.
Smelting
Once terms are agreed, feeds are combined together into much larger batches for smelting. In this pyrometallurical process, material is melted at over 1200°C for around 12 hours in large reverberatory furnaces to separate the non-metallic components. Two types of bullion feed are produced: a silver based feed containing primarily platinum and palladium, and an iron based feed which contains all five of the PGMs.
Chemical Leaching
The two bullion feeds then move to our chemical leaching plant where they undergo multiple leachings to further concentrate the PGMs into solution. The silver based bullion is suspended in concentrated acid to slowly leach the silver, platinum and palladium into solution and separate out any gold, which is sent for further refining. The iron based bullion is also acid leached but follows a different chemical treatment route, given the different solubilities of the five PGMs that it contains.
Chemical Separation
Chemical separation is a highly complex multistage process that converts the five PGMs into their final product forms, commonly a PGM sponge. It involves dissolution and a series of solvent extractions, evaporation, precipitation and filtration steps to produce highly pure salts for each PGM. These salts then undergo heat treatment to convert them to the final pure precious metal.