Gold (AU) not less than 65%.
Silver (AG) not more than 10%.
The process involves to dissolve gold in Aqua regia ( Acid+Water Mixture ).Silver will form Silver chloride precipitates, which will be ﬁltered out.The ﬁltered solution is treated with a Reducing agent Sodium Meta Bisulﬁte, and precipitates Gold, which is ﬁltered, washed , dried and usually melted and granulated.
Std Reﬁning capacities per Batch - 2kg, 5 kg, 10 kg, 20 kg, 25 kg.
The most used reﬁning technique is based on chemical method whereby the gold- bearing scrap is dissolved in aqua regia (HNO3 + HCl). The aqua regia reﬁning technique efﬁciently works with alloys that respect the contents of silver less then 10%.
The silver percentage in the alloy represents a critical value to be considered in order to use the aqua regia reﬁning technique. A high silver concentration, indeed, may block the reaction due to the exceeded amount of AgCl formed during the chemical attack. An alternative method for gold reﬁning applied to high silver content alloys is the “inquartation procedure. Inquartation involves initially diluting the gold in the reﬁnable material to about 25% (literally ‘quartering’ the gold) by melting with the appropriate addition of copper or silver, then treating with nitric acid. The acid will dissolve the silver and base metals, leaving behind the gold. The acid treatment is known as parting as it ‘parts’ (separates) the gold from the silver and base metals. Dilution of the gold content is necessary to ensure that the nitric acid can readily attack and dissolve the base metals and silver, some of which may be otherwise masked by the gold.
Epoxy quoted structure and Polypropylene (PP) panelling. Staircase , handrail, and platform.
Granular Raw material is reacted with Nitric acid, dissolving the silver content, which is then seperated and precipitated out by a reducing agent. This precipitated metal is enriched silver which is washed and taken for electroytic reﬁning to achieve highest purity
Other process in reﬁning
Electrolytic reﬁning processes in Gold and Silver reﬁning, however we endeavour to offer the complete state of the art processes.
WE OFFER COMPLETE SOLUTIONS OF ASSAY LAB WHICH INCLUDES CUPELLATION METHOD BY FIRE ASSAY.
The plant is composed of two sections: one is used to neutralize concentrated fumes (Nox) with an oxidizing solution, the second to neutralize fumes with an alkaline solution. The oxidizing section is composed of one scrubber where an acid solution is sprayed thought nozzles into the fume flow, and two scrubbers into which fumes are washed with an alkaline solution.
In details, the fumes scrubbing plant is composed of:
Scrubbers made in PP with right diameter 900mm complete of filling packs, spray systems, distribution and re-distribution and piping system
We undertake the installation, and process commissioning, training of the precious metal reﬁning plant.