AR the best method for GF???

beekrock · Feb 25, 2011

OK. I've been lurking around on these boards for a few days and have been reading all I can about the different acids, etc.

Right now I'm looking to refine 1lb. of gold-filled jewelry. Correct me if I'm wrong, but from what I've read real AR is the best solution for gold-filled items, except for the fact that nitric is more expensive than the components of other methods?

So, very generally speaking, for 1lb. of GF, how much would it run to refine using the AR method (assuming one already has the lab equipment)? While I'm at it, how much nitric would be needed to refine 1lb. of GF?

Palladium · Feb 25, 2011

Have you read Hoke? It's in my sig line below. I think she gives all the numbers for what your asking. Welcome to the forum.

Harold_V · Feb 27, 2011

beekrock said:
Right now I'm looking to refine 1lb. of gold-filled jewelry. Correct me if I'm wrong, but from what I've read real AR is the best solution for gold-filled items,

Not in my opinion. I can't imagine where you might have read that on this forum---unless it was from someone that knows almost nothing. I don't recommend AR for any recovery process with one very rare exception. Wise people eliminate base metals before they dissolve values. Gold filled is predominantly base metal.

Harold

glondor · Feb 27, 2011

I believe the gold filled is best done with a sulphuric gold cell. Easy to make and operate. Read the many posts about gold cells.

FrugalEE · Feb 27, 2011

Beekrock,

I recently finished my first batch of GF jewelry. I carefully sorted my mixed batch into different types. I chose 29.7 grams of 1/20 12K for my first run. I would never recommend starting with a pound of mixed GF and I certainly would take out the silver colored objects or anything else weird and treat them separately. Also when it comes to expansion watch bands you need to remove the springs and other items without gold.

Over 97.5% of the weight of 1/20 12K is going to be base metal and I searched the forum for the required amount needed to dissolve copper. I use an equal amount of water with 67% nitric. I added about 2/3 of the calculated nitric initially and then added small amounts until I got rid of the base metal. At one point I suspected I had overdone the nitric so I added more GF pieces keeping track of their weight. I ended up using 87.6 ml of nitric for 29.7 grams of GF at a cost to me of 41 cents. (I get it locally at $18 per gallon.)

I used another 0.5ml of nitric to make the AR to dissolve the gold. Since that is hard to measure I calibrated my eye dropper (35 drops = 1 ml.) Since I was careful not to overdo the nitric in the AR all I had to do was dilute with water and add SMB powder of a bit more weight than the gold I expected, again I learned that from a board search. I got .668 grams of dry gold powder which represents 2.25% of the total weight. That's not bad considering wear and a theoretical max of 2.5%.

I've got a larger batch in process now and got one surprise in finding 3 little foam pillows floating in the nitric. They must have come from the cuff links.

I've left out a lot of details like using heat and saving everything so I can test and make sure I'm not leaving anything valuable behind.

Hope this helps,

FrugalEE

Lou · Feb 27, 2011

If I were doing many hundreds pounds of it, I'd melt, sample, and assay it and ship it to a copper refiner.

If I were doing just 10-50 pounds at a time, I'd melt it, add more copper and part in a copper sulfate cell to which a little sulfamic acid has been added. Slimes are the gold.