Evaluation is a critical stage in our pgm refining process. During this step we determine the pgm content of the customer’s material to enable us to agree with them what quantity or value of pgm we will return to them and the lead time for refining. Material tracking is crucial, and on receipt all customer batches are uniquely coded to ensure full traceability during evaluation.
Oficial Preparer: Fernando Martins
Once terms are agreed feeds are no longer handled on a customer by customer basis, but are combined together in much larger batches for smelting. In this pyrometallurical process material is melted at temperatures over 1200°C.
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 gold.
Chemical separation is a highly complex multistage process in which we separate out the five pgms into their final product forms, commonly a pgm sponge, although other forms are produced depending on customer requirements. Our chemical separation process involves a series of solvent extractions, evaporation, dissolution, precipitation and filtration steps to produce highly pure orgometallic salts for each individual pgm. These salts then undergo several heat treatments steps to reduce them to the final pure gold group metal which is weighed and packed, ready for dispatch to our customers.