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Hi folks! I hadn't been here in awhile. Heck, perhaps a few years. I hope you've all been well.
I'm a jewelry designer / fabricator, and a scrap gold buyer. I've been buying gold filled stuff for a while. It's piled up and I wanted to get rid of it.
I found a refiner that will process my gold filled scrap. They pay 90%. I melted it (oxy propane) (over 600 grams), but didn't have a mold to pour it into, so I just let it cool off in the crucible. I then broke the crucible off.
I "polished" the blob with a wire wheel grinder, then pickled it for a few minutes in a sodium bisulfate solution.
I analyzed the bar with my XRF, and got readings between 4% and 6%. Obviously, that's higher than what you'd expect out of gold filled, but perhaps there were some pieces with GF clasps that were actually karat gold.
I sent to the refiner. He remelted and pulled pin samples. He stated his analysis was 1.77%. Hmmm. When I analyzed the pins, I got between 3% and 5%. Granted, my XRF isn't calibrated at those low levels.
I didn't accept his offer, politely, so he sent them back. I have the pins and the blob now.
I'm sending the pins to a friend who has a different model xrf so she can analyze them.
What options do I have for determining the actual gold content in these pins? (I've refined Au and Ag several times, but only have about 1 liter of nitric acid left)
- I suppose I could weigh the pins (10.7 grams each) and dissolve into nitric. Then collect the Au particulates, weigh and go from there. But 2% of 10.7 grams isn't a lot. I'm worried about recovery affecting my yields.
- I suppose I could ask one of you to perform a fire assay.
- I have cupels and an assay oven. But I've never performed one and am worried about how accurate my first tries would be.
I would appreciate any advice...
I'm a jewelry designer / fabricator, and a scrap gold buyer. I've been buying gold filled stuff for a while. It's piled up and I wanted to get rid of it.
I found a refiner that will process my gold filled scrap. They pay 90%. I melted it (oxy propane) (over 600 grams), but didn't have a mold to pour it into, so I just let it cool off in the crucible. I then broke the crucible off.
I "polished" the blob with a wire wheel grinder, then pickled it for a few minutes in a sodium bisulfate solution.
I analyzed the bar with my XRF, and got readings between 4% and 6%. Obviously, that's higher than what you'd expect out of gold filled, but perhaps there were some pieces with GF clasps that were actually karat gold.
I sent to the refiner. He remelted and pulled pin samples. He stated his analysis was 1.77%. Hmmm. When I analyzed the pins, I got between 3% and 5%. Granted, my XRF isn't calibrated at those low levels.
I didn't accept his offer, politely, so he sent them back. I have the pins and the blob now.
I'm sending the pins to a friend who has a different model xrf so she can analyze them.
What options do I have for determining the actual gold content in these pins? (I've refined Au and Ag several times, but only have about 1 liter of nitric acid left)
- I suppose I could weigh the pins (10.7 grams each) and dissolve into nitric. Then collect the Au particulates, weigh and go from there. But 2% of 10.7 grams isn't a lot. I'm worried about recovery affecting my yields.
- I suppose I could ask one of you to perform a fire assay.
- I have cupels and an assay oven. But I've never performed one and am worried about how accurate my first tries would be.
I would appreciate any advice...