REFINING SERVICES
Gold
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At the refinery, the dore bars are put through the Miller process. This is an industrial chemical procedure that blows a stream of chlorine gas through molten dore metal.
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Silver and other metals will react with the chlorine, causing a silver chloride slag to form on the surface. The molten gold is then cast into odd-weight 400 oz bars that have a 99.5 per cent purity level, which can then be released onto the market.
The silver chloride is put through a leaching process to remove other metals and then reduced to metallic silver via electrolysis.
Making 99.9 per cent gold
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The refinery can process the 99.5 per cent molten gold even further, resulting in 99.9 per cent bars for investors.
This requires an electrochemical procedure called the Wohlwill process, which involves casting the gold into anodes and placing them into a hydrochloric acid bath. When an electric current is run through the anodes, the gold dissolves and is plated onto a cathode.
The final product is 99.9 per cent purity, although the cathode still needs to be melted down, granulated and then measured out into the right quantities for casting. The AZGAR TRADING produces gold bars ranging from half an ounce up to 1 kg.
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Silver
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Producing silver uses similar methods to refining gold, although during the electrolytic part of the procedure, the silver anode is instead dissolved in nitric rather than hydrochloric acid.
However, the cathodes are still 99.9 per cent purity and the process afterwards is much the same, although silver is typically cast into 100 oz or 1 kg bars.
Platinum Group Metals
Azgar Trading offers its clients a range of PGM refining services. The refinery specialised PGM laboratories can treat high-grade and low-grade platinum, palladium and rhodium and other bi-metals in the form of residues, spent industrial equipment, recycled material and concentrates. We follow a four step process:
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1. 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.
2. 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.
3. 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.
4. Chemical Separation
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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.
