My first silver bar, refined from sterling silver using nitric acid. Poured into a graphite mold via a desktop electric furnace.
For a first run, I'm pretty happy with the results. The next step is refinement via electrolytic cell to further purify. I definitely had to dust off some wet chemistry skills I haven't used in about 16 years. I do miss working in an actual laboratory space with all the conveniences. Adapt and overcome! Thank goodness for surplus lab equipment. (I contacted the Chemistry Departments of three local universities and due to liabilities, they would not sell chemicals or rent lab space. Time to use that GI Bill and get into Grad School!)
The entire process of refinement to this point, I've broken down into steps:
1.) Procurement (challenging at first) of sterling silver was quite a challenge, and across the forum is of course the best kept secret. I finally found a solution, which provided assayed/verified sterling at up to 75% below spot price. Also, flatware is much easier to process rather than jewelry. Prying out all the little gems, cement, cardboard and other junk they add to sterling is huge inconvenience. I still have a sterling tube necklace filled with a plastic/wax resin that won't melt out. I think I’ll have to incinerate it out.
2.) Dissolving (most dangerous) in 50/50 by volume boiling nitric acid/distilled water. I do not have a fume hood, so this reaction has to be conducted outside, usually on a breezy day. I’m currently doing small batches in a 1000mL beaker with a watch glass on top. I did manage to pick up a 10”x10” corning hot plate/stirrer which is great for heat and mixing. I torch the sterling until it develops a patina and then let cool before adding it to the acid. I did make one mistake here that I’d like to share. I bought a used 9”x9” glass baking dish for secondary containment between my beaker and my hot plate. I assumed it was borosilicate “Pyrex” glass. I was wrong with my assumption and so when I turned off the hotplate (which holds considerable heat), the edges of the dish cooled faster than the bottom. It was like a gunshot went off as it exploded. (Nobody was hurt) It did crack the bottom of my beaker but thankfully no solvent loss. Next time I’ll use real Pyrex for this. After dissolving, the mixture was filtered via vacuum filtration.
3.) Precipitation (requires most patience) or cementing of the silver was done via 4-gauge copper wire which was turned into a coil and hook to hang from the side of the beaker. My first attempt my silver concentration was too high and it created a solid silver barrier on the wire, preventing further precipitation. Dilution with distilled water assisted this issue. A new coil was added and the silver would easily fall off the wire. The entire reaction took a few days to complete and I let it run until the copper was “red” in color. Once complete the silver powder was washed approx. 10-times with boiling water. All of the solvent and washing was captured into a “silver stock pot” which is where I stored the used silver coils. The silver powder was dried overnight in a “Little Dipper” crock pot.
4.) Melting and pouring (brand new to me) the silver powder to ingots and cornflake for a silver cell was challenging. To much borax in one pour, not pouring fast enough, not being hot enough to retain heat throughout the pour, mold not hot enough, dropping the hot mold in the quench, cracking the edges of the fragile graphite mold, not fully closing the furnace and sublimating the graphite crucible. Needless to say, this was a trial by fire (literally). After working past these learning experience and doing considerable amounts of research into actual metallurgy I got a pour I’m happy with.
5.) Electrolytic Refinement (a work in progress) is my next step on this journey. More to follow once I sort it all out.
Outcome: In the end, I came out with approx. 650grams of dried silver powder. I poured the 167g /5.9oz bar in the picture below and rest was “cornflaked” and is being used in a silver cell for further purification.
Special Note: I would like to take a moment and thank Streetips/Kadriver for his YouTube series. I found his videos to be very educational and his wet chemistry skills to be quite professional. Along with that, the members of this forum have provided excellent advise which I have enjoyed reading.
--Elemental
For a first run, I'm pretty happy with the results. The next step is refinement via electrolytic cell to further purify. I definitely had to dust off some wet chemistry skills I haven't used in about 16 years. I do miss working in an actual laboratory space with all the conveniences. Adapt and overcome! Thank goodness for surplus lab equipment. (I contacted the Chemistry Departments of three local universities and due to liabilities, they would not sell chemicals or rent lab space. Time to use that GI Bill and get into Grad School!)
The entire process of refinement to this point, I've broken down into steps:
1.) Procurement (challenging at first) of sterling silver was quite a challenge, and across the forum is of course the best kept secret. I finally found a solution, which provided assayed/verified sterling at up to 75% below spot price. Also, flatware is much easier to process rather than jewelry. Prying out all the little gems, cement, cardboard and other junk they add to sterling is huge inconvenience. I still have a sterling tube necklace filled with a plastic/wax resin that won't melt out. I think I’ll have to incinerate it out.
2.) Dissolving (most dangerous) in 50/50 by volume boiling nitric acid/distilled water. I do not have a fume hood, so this reaction has to be conducted outside, usually on a breezy day. I’m currently doing small batches in a 1000mL beaker with a watch glass on top. I did manage to pick up a 10”x10” corning hot plate/stirrer which is great for heat and mixing. I torch the sterling until it develops a patina and then let cool before adding it to the acid. I did make one mistake here that I’d like to share. I bought a used 9”x9” glass baking dish for secondary containment between my beaker and my hot plate. I assumed it was borosilicate “Pyrex” glass. I was wrong with my assumption and so when I turned off the hotplate (which holds considerable heat), the edges of the dish cooled faster than the bottom. It was like a gunshot went off as it exploded. (Nobody was hurt) It did crack the bottom of my beaker but thankfully no solvent loss. Next time I’ll use real Pyrex for this. After dissolving, the mixture was filtered via vacuum filtration.
3.) Precipitation (requires most patience) or cementing of the silver was done via 4-gauge copper wire which was turned into a coil and hook to hang from the side of the beaker. My first attempt my silver concentration was too high and it created a solid silver barrier on the wire, preventing further precipitation. Dilution with distilled water assisted this issue. A new coil was added and the silver would easily fall off the wire. The entire reaction took a few days to complete and I let it run until the copper was “red” in color. Once complete the silver powder was washed approx. 10-times with boiling water. All of the solvent and washing was captured into a “silver stock pot” which is where I stored the used silver coils. The silver powder was dried overnight in a “Little Dipper” crock pot.
4.) Melting and pouring (brand new to me) the silver powder to ingots and cornflake for a silver cell was challenging. To much borax in one pour, not pouring fast enough, not being hot enough to retain heat throughout the pour, mold not hot enough, dropping the hot mold in the quench, cracking the edges of the fragile graphite mold, not fully closing the furnace and sublimating the graphite crucible. Needless to say, this was a trial by fire (literally). After working past these learning experience and doing considerable amounts of research into actual metallurgy I got a pour I’m happy with.
5.) Electrolytic Refinement (a work in progress) is my next step on this journey. More to follow once I sort it all out.
Outcome: In the end, I came out with approx. 650grams of dried silver powder. I poured the 167g /5.9oz bar in the picture below and rest was “cornflaked” and is being used in a silver cell for further purification.
Special Note: I would like to take a moment and thank Streetips/Kadriver for his YouTube series. I found his videos to be very educational and his wet chemistry skills to be quite professional. Along with that, the members of this forum have provided excellent advise which I have enjoyed reading.
--Elemental
![IMG_0441[1].JPG](https://cdn.imagearchive.com/goldrefiningforum/data/attachments/31/31022-d53d37992529c0b86802f2c48164e611.jpg)
