How to Refine Gold Jewellery – Inquartation Methode (DIY) P. 1


Hi everybody In this video I will demonstrate the refining
of gold from old karat jewelry. Here’s our scrap gold, 36.12 grams of 18 karat
and 33.05 grams of 14 karat. The first step in this process is to calculate
the amount of silver that should be added in order to make the alloy into a 6 karat, meaning, one quarter of the alloy is gold
and the rest is silver or copper or other elements that are soluble in nitric acid. For inquarting, I always use scrap sterling
silver. This basically gives the opportunity to hit two birds with one stone as I also get to refine the silver from the scrap sterling. For the amount of 18 karat scrap i have here,
I’ll need to add 72.24 grams of sterling silver and for the amount of 14 karat scrap I’ll
add 44.03 grams. All in all, the result is 185.44 grams of
6 karat gold alloy. You can calculate it yourself… Or you can
simply use the calculator on my website… it’s pretty self-explanatory… here’s the
link. I’ll leave it here in the corner for a while.. Alright… The next step is to melt everything
together. Keep in mind that the alloy needs to be homogenous…
so that means to stir the liquid metals thoroughly. Of course, if you are melting the scrap with
an induction furnace, stirring is not necessary. To granulate the metal, I will pour the molten
metal into a bucket filled with water from a height of about a foot and a half. The water
depth is about 14 inches. OK… here we go… Pouring the molten metal from this height
produces shot which has large surface area, quite similar to corn flakes. The metal granules are placed in a reaction
vessel and placed on a hot plate. Here you can see the addition of the 50/50 nitric acid
solution. That means half of the solution is 70% nitric
and the other half is distilled water. The nitric leach usually takes about 2 to
3 hours at near boiling temperature. The acid will dissolve all of the silver and
other base metals such as Copper, Nickel and Zinc into the solution. Here, I have decanted the solution which reveals
the gold sponge. As you can see, the structure of the corn
flakes is still intact. This is exactly what we want because it is easier to wash this
way. Keep it intact as it is very brittle. By the way, some refiners would choose to
perform another Nitric leach at this point using a slightly more concentrated acid, meaning
1 part distilled water and 2 parts 70% Nitric. I find it useful as well. The next step is to clean the gold sponge
from the silver and base metals solution. To do that, we will wash the sponge several
times with boiling hot distilled water. Repeating these washes three to five times
would be enough. The wash water is kept separate so it could be re-used on the next batch. Time to dissolve the gold with a hot Aqua-Regia. Two things happen immediately as the Hydrochloric
acid is added: first – Some Silver Chloride forms and re-dissolves, we will deal with
it later on in the process. Second – Some gold starts to dissolve and
give color to the solution. As the solution heats up, you can clearly
see the gold being dissolved before any Nitric acid addition. I have time-lapsed the gold dissolution, though
even at this speed you can clearly see whenever a small increment of nitric acid is added.
Every addition is allowed to react until it is exhausted. The point is, to add just enough nitric acid
to dissolve the metals. That’s it. Please, do NOT follow recipes that calls for
pre-mixing the Aqua-Regia. Just in case you are wondering, here’s a little
behind the scenes snapshot of the setup. If you have any question about it, just leave
it on the comment section below. When the dissolution of the gold is done,
the solution is diluted three times over with water to precipitate the traces of Silver
chloride that was previously dissolved. Again, I forgot to film it, but a few milliliters
of Sulfuric acid were added carefully to the dilute gold solution to precipitate traces
of Lead just in case there was any in the solution. The gold solution is left to stand overnight
to cool down and precipitate Silver chloride and Lead sulfate.

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