Since silver is a malleable precious metal, it's necessary to combine it with another metal (copper is the most commonly used metal) in order to increase its mechanical strength.

Silver 800 is the poorest alloy entitled to the term pure silver. Its brilliance is not comparable with that of sterling silver (or silver 925) or that of silver 950.

Beyond silver 800, the problem of recycling arises for all silver alloys, residues of the manufacture of silver jewelry : dust, chips and pieces of silver solder that are on the jeweler's workbench.

 

bench pin

 

Recycling begins with recovery

In order to recycle these silver residues, the artisan jeweler recovers all the residues in a container that will contain dust and debris of silver, of different purity. It can either melt to make a single nugget of poor silver, or keep them in a container.

 

recycling

 

To extract pure silver from these silver alloy residues, these metal pieces must be dissolved in concentrated nitric acid. This process generates toxic vapors of nitrogen dioxide (NO2), so it is important to do so outdoors or in a well-ventilated area.

nitric acid

 

Metallic silver then became ionic, in the form of AgNO3 dissolved in the acidic solution. This is diluted with distilled water and then we incorporate a clean copper tube, which by oxidation-reduction reaction will crystallize the pure metallic silver. The latter, denser than the solution, falls to the bottom of the container and can be recovered by filtration.

The silver thus recovered is contaminated with acid residues, so it must be washed with distilled water (see video below). It is then dried and melted to give a large nugget of pure silver to nearly 98%.

 

Video showing the process of recycling poor silver in pure silver (fr) :



Obtaining pure silver

 Silver coin

(Silver 99%) 

If one wants to obtain pure silver, it's necessary to treat the silver previously obtained by electrolysis. We thus immerse our nugget in a solution of silver nitrate, it will serve as anode and under the action of the current will turn into Ag + ions. At the same time, a cathode made of silver will allow the silver ions of the solution to crystallize. The result is 99.9% pure silver crystals.

 

For further : 

 

August 19, 2019 — Hugo Maherault

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