Before it becomes a bar, silver must be refined: this is the step that turns a raw, impure metal into 999 fine silver, the investment-grade standard. Refining lies at the heart of the great refineries’ expertise. Here is how it works.
Why refine silver
Silver never arrives at the refinery in pure form. It comes as:
- concentrated ore, often mixed with lead, zinc or copper;
- doré, a raw alloy containing both gold and silver, extracted from mines;
- recovered silver (jewellery, silverware, industrial scrap).
Refining separates silver from these other metals to reach a guaranteed purity. Without this step, there is no 999 fineness, and therefore no investment-grade bar.
The main refining processes
Electrolysis (Moebius process)
This is the benchmark method for silver. The impure metal is cast into anodes, which are immersed in a silver nitrate bath. Under the effect of an electric current, the silver dissolves at the anode and then redeposits as very pure crystals on a cathode, while the impurities fall to the bottom or remain in solution. The Moebius process routinely reaches purities above 999. We devote a dedicated article to it: silver electrolysis.
Cupellation
An old process, still used for assaying and refining: the metal is melted with lead in a porous cupel, under a stream of hot air. The lead and base metals oxidise and are absorbed by the cupel, leaving pure silver (and gold). This is also the basis of the fire assay, the benchmark method for assaying a precious metal.
The Balbach-Thum process
A historical electrolytic variant, used in particular to separate gold and silver from doré, with a horizontal arrangement of the electrodes.
Separating gold and silver
Doré contains both metals. Their separation often relies on acid refining (silver dissolves in nitric acid, gold remains solid) or on electrolysis. In the end, gold and silver are recovered separately, each at its investment-grade fineness.
From refined metal to bar
Once refined, 999 silver comes as granules or cathodes. It is then ready for melting and shaping, whether by casting or minting. Refining is therefore only the first brick in a chain we detail in how silver bars are made.
Who refines silver
Investment-grade refining is carried out by accredited refineries, the best of which appear on the LBMA’s Good Delivery List: Metalor, Heraeus, Argor-Heraeus, Valcambi, PAMP, Asahi Refining… Their hallmark on a bar is a guarantee of fineness and traceability. Discover how a silver refinery works.
What refining means for you
- The fineness of your bar (999 vs 925) follows directly from the quality of the refining, and it is this that determines the buy-back value.
- A bar from a recognised refiner resells without complex appraisal, because its purity is presumed reliable.
- On resale, your silver is valued at its melt value: the weight of fine silver it contains.
In summary
- Refining purifies raw silver up to the investment-grade 999 fineness.
- The leading process: electrolysis (Moebius); other methods: cupellation, Balbach-Thum.
- It precedes the melting and shaping of the bar.
- An LBMA-accredited refiner guarantees purity and liquidity.
To find out the value of your fine silver, check the silver price and request a free valuation.
This article is informational and does not constitute investment advice.