Do you have old pieces of gold jewelry sitting at home that are damaged or not your style to wear and you wonder if you could turn them into new pieces you like or even get cash for them?
Melting an old gold ring into a new one is not a straightforward process and is often very costly because of the amount of labor involved. If you are not sentimentally attached to that very piece of gold, getting the cash value from refining it is actually a much better option.
After having all gemstones removed by a setter, you bring your gold pieces to a refinery but what do they do with it? I brought my silver scraps to a precious metal refiner in NYC and followed the first steps of its purification and recycling.
I spend a lot of time at my bench: sawing and filing precious metal castings of my designs, cutting wire to make rings and polishing pieces to give them a smooth surface. All these processes create a lot of scraps and jewelry sweeps that should be collected and recycled to re-enter the circuit of metal processing. It is a win-win: you get cash from something otherwise wasteful and you contribute to lower the proportion of precious metal mining detrimental to the environment.
After collecting all my silver jewelry manufacturing byproducts, I brought them to a precious metal refinery in Diamond District, NYC. I was lucky enough to witness the transformation of my mixed bag of scraps into a solid fine silver ingot. Hereafter, I describe the different stages involved in the refining process.
First, all the silver scraps are weighed to determine how much bulk material we are starting with. Then they are placed inside a crucible. A crucible is a container that can withstand very high temperatures, it is usually made out of graphite or porcelain. That vessel is then placed inside an induction furnace that heats up to 1500 C (2732 F). For reference, Gold melts at 1064C (1948 F) and Silver at 962C (1763F).
Borax powder is then added to the melting mix for two reasons: first, it lowers the melting temperature of metals, enabling the refiner to use less energy to melt the scraps. Second, it helps to absorb impurities from the mix. It works by dissolving oxides and producing a fluid borate slag that is of lesser density and floats on the surface of the molten metal. Precious metals such as Platinum, Gold, Silver, Palladium and Rhodium are unaffected by this reaction and sink to the bottom of the mixture, intact.
To verify that all elements of the mixture are molten, a rod made up of carbon-graphite or clay is regularly dipped and stirred inside the crucible. Once every impurity has effectively been dissolved, it is time to pour the mix into a mold. The refiner grabs the red hot crucible with long tongs and then pours the lava-like mix into a mold usually in the shape of a brick or a pyramid.
The content of the mold is left to cool down for a few minutes, one can observe the shiny red metal becoming darker. Once the silver is entirely set at the bottom of the mold, it is taken out and submerged with cool water to harden it, this is called the quenching process.
The resulting silver ingot is then hammered to further harden it and it is now ready to be weighed and tested by an X-ray fluorescence machine to determine its purity and thus its cash value. It will be further refined to be pure enough to re-enter the metal manufacturing chain and become a new piece of jewelry!