I own a jewelry shop And we have a substantial amount of polishing's from machines and floor sweeps. A little over 50 pounds. I have been incinerating this material for the past few days. I am keeping the polishing's separate from the floor sweeps. I probably should say that we work primarily in 18 karat and platinum. I am ready to remove all the magnetic material. The next step is where I'm a bit confused. I have been doing an awful lot of reading and see where some are recommending nitric and some are recommending HCl for the first acid treatment. The volume of material that I have is very substantial even after burning. My intent was to process it through that point and do some assaying and then possibly sending the material to a refinery at that point. I need some clarification as to what is best to use, The nitric or the HCl. I am open to any suggestions and welcome them. I am a new member here but have been working in the jewelry industry for quite some time. Thank you and events for any and all responses. Jack
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upcyclist
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A few thoughts:
What color is your incinerated material? That will help us figure out if you're actually done incinerating or not
HCl is often used first for two reasons: 1) if you expect tin, which I expect you wouldn't, because tin + nitric acid = metastannic acid, which is a mess; 2) HCl is cheaper than nitric for most, and removes many of the base materials, but not so much with copper and silver. I would think you could go straight to nitric, though others will know more. Also, any time you switch between HCl & nitric, you need to roast your material to avoid creating aqua regia before you're ready for it.
If you post your location, you might also find a member willing to come see what you've got.
And welcome to the forum!
--Eric
What color is your incinerated material? That will help us figure out if you're actually done incinerating or not
HCl is often used first for two reasons: 1) if you expect tin, which I expect you wouldn't, because tin + nitric acid = metastannic acid, which is a mess; 2) HCl is cheaper than nitric for most, and removes many of the base materials, but not so much with copper and silver. I would think you could go straight to nitric, though others will know more. Also, any time you switch between HCl & nitric, you need to roast your material to avoid creating aqua regia before you're ready for it.
If you post your location, you might also find a member willing to come see what you've got.
And welcome to the forum!
--Eric
Upcyclist,
Thank you for the welcome. We are in western PA. The incinerated material was burned in flat stainless steel pans at night until the was zero glowing material, and still another 15 to 20 min longer. The material is primarily a purplish grey. There is some that is a bit lighter.
Thanks again, jack
Thank you for the welcome. We are in western PA. The incinerated material was burned in flat stainless steel pans at night until the was zero glowing material, and still another 15 to 20 min longer. The material is primarily a purplish grey. There is some that is a bit lighter.
Thanks again, jack
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=2498&hilit=buffing
Before jumping into this, I would certainly read this entire thread, especially Harold's posts, especially the one dated Sun Mar 15, 2009 3:20 am. I would run a small batch first, say 100g. Harold probably has run more batches of Buffing dust and sweeps, hands on, than anyone else I can think of.
Part of the learning curve on this forum is to figure out who are the best people to listen to, for each of the the various processes. And, never jump full-blast into something you haven't done before or feel unsure of. Always run one or more small samples first until you get a feeling for it.
Before jumping into this, I would certainly read this entire thread, especially Harold's posts, especially the one dated Sun Mar 15, 2009 3:20 am. I would run a small batch first, say 100g. Harold probably has run more batches of Buffing dust and sweeps, hands on, than anyone else I can think of.
Part of the learning curve on this forum is to figure out who are the best people to listen to, for each of the the various processes. And, never jump full-blast into something you haven't done before or feel unsure of. Always run one or more small samples first until you get a feeling for it.
If you incinerated it until the charge was glowing and then left it an additional 20 minutes you are done with the incineration part.
It is not unusual for jewelers to take a 1 pound sample from their refiner after it is burnt crushed and sifted so they can process the pound in acid in their shop to serve as an assay. Much like GSP has suggested. Please make sure you take a sample from well mixed material so it is representative of the entire lot. You should take it to your refiner of choice and let them crush and sift the material and give you the one pound sample. This way they know you have the same material as them. If you just take a one pound sample yourself and mail off the 50 pounds, then all bets are off.
I have taught a good number of small refiners how to process sweeps in Aqua regia to recover the gold themselves in house. The method I always tell them to use is Harold's method which Chris referenced. However there is one thing you must remember, and this holds true for every refiner I have ever assayed sweeps refining residues for, you will not get all of the gold. The average left behind is 1/4 of 1% and all of the silver remains as well. So refiners end up incinerating the residues a second time and shipping them out with low grade prepared sweeps as they are still payable after all of the charges.
It is not unusual for jewelers to take a 1 pound sample from their refiner after it is burnt crushed and sifted so they can process the pound in acid in their shop to serve as an assay. Much like GSP has suggested. Please make sure you take a sample from well mixed material so it is representative of the entire lot. You should take it to your refiner of choice and let them crush and sift the material and give you the one pound sample. This way they know you have the same material as them. If you just take a one pound sample yourself and mail off the 50 pounds, then all bets are off.
I have taught a good number of small refiners how to process sweeps in Aqua regia to recover the gold themselves in house. The method I always tell them to use is Harold's method which Chris referenced. However there is one thing you must remember, and this holds true for every refiner I have ever assayed sweeps refining residues for, you will not get all of the gold. The average left behind is 1/4 of 1% and all of the silver remains as well. So refiners end up incinerating the residues a second time and shipping them out with low grade prepared sweeps as they are still payable after all of the charges.
I have treated many many jewellery sweeps over the years so perhaps I can add a few pointers.
Now you have your incinerated material you need to crush and sieve the material and then use your magnet to remove the magnetics but as you work with Pt you could remove substantial amounts if the alloys are cobalt based so keep all small fragments and treat separately.
As you are unlikely to have much silver I'd suggest a good HCl boil, this will remove much base metal and make filtering easier, you need to actually boil your sweeps but also to keep stirring to avoid hotspots and broken beakers, once you have let the sweeps and solution cool filter the used HCl off and return the material to the beaker, add plenty of HCl and put back onto the heat then add small, very small additions of nitric, you add too much you will get a boil over, after the initial reaction stir carefully to mix the nitric into the body of material again slowly, the solution should be boiling slightly so keep stirring, once the reaction slows or stops add another small addition of nitric and follow the proc sure above until all rectify stops after the addition of nitric, to make sure all the material has reacted always add a further addition of HCl to make sure you have a little free chlorine available, if you get no reaction allow to cool, keep stirring while hot, and filter.
You may well need to do this several times to recover all the values, if you do it correctly the first dissolution will recover 90% of the values so if on the second you get 20% more you need to do it again .
You should allow plenty of time on the heat to allow the Pt to dissolve.
Be aware PGM salts are very toxic whether in solution or powders so take appropriate care as regards your safety.
Good luck and if you need more information please ask and if I can help I will.
Now you have your incinerated material you need to crush and sieve the material and then use your magnet to remove the magnetics but as you work with Pt you could remove substantial amounts if the alloys are cobalt based so keep all small fragments and treat separately.
As you are unlikely to have much silver I'd suggest a good HCl boil, this will remove much base metal and make filtering easier, you need to actually boil your sweeps but also to keep stirring to avoid hotspots and broken beakers, once you have let the sweeps and solution cool filter the used HCl off and return the material to the beaker, add plenty of HCl and put back onto the heat then add small, very small additions of nitric, you add too much you will get a boil over, after the initial reaction stir carefully to mix the nitric into the body of material again slowly, the solution should be boiling slightly so keep stirring, once the reaction slows or stops add another small addition of nitric and follow the proc sure above until all rectify stops after the addition of nitric, to make sure all the material has reacted always add a further addition of HCl to make sure you have a little free chlorine available, if you get no reaction allow to cool, keep stirring while hot, and filter.
You may well need to do this several times to recover all the values, if you do it correctly the first dissolution will recover 90% of the values so if on the second you get 20% more you need to do it again .
You should allow plenty of time on the heat to allow the Pt to dissolve.
Be aware PGM salts are very toxic whether in solution or powders so take appropriate care as regards your safety.
Good luck and if you need more information please ask and if I can help I will.
In the late 90's, early 2000's, a friend of mine traveled the country buying lots of buffing dust and sweeps from jewelers. I had some spare time and spent a lot of it helping him out on the processing/assaying over a 4 years period of time. He had accounts with some of the big chains and 200 pound lots of buffing dust were not unusual. While he was on the road, I ran the process, which involved incineration, ball milling, magnetics removal, screening, sampling and assaying.
At that point, this is considered to be "prepared sweeps", in the trade. In other words, it was prepared to the point where it could be accurately sampled, assayed, and then shipped to a proper (usually large) refiner. My assays were typically within about 0.2% of the refiner's assays which, of course, can always be expected to be the one on the low side. We also did splitting limits. Back then, most of the jewelers doing Pt tended to specialize in it, so that dust was mostly Pt. Mostly, though, the dust was a mix and mainly gold. The settlements he got were excellent. It was more profitable to ship the prepared sweeps than it would be to refine it himself.
At that point, this is considered to be "prepared sweeps", in the trade. In other words, it was prepared to the point where it could be accurately sampled, assayed, and then shipped to a proper (usually large) refiner. My assays were typically within about 0.2% of the refiner's assays which, of course, can always be expected to be the one on the low side. We also did splitting limits. Back then, most of the jewelers doing Pt tended to specialize in it, so that dust was mostly Pt. Mostly, though, the dust was a mix and mainly gold. The settlements he got were excellent. It was more profitable to ship the prepared sweeps than it would be to refine it himself.
The problem with shipping prepared sweeps for a small refiner is usually cash flow. I always preferred to ship prepared sweeps but we were always able to ship lots of at least two full 55 gallon drums twice a month, plus the gold prices then were more stable. Today, speculation can cause the metal price to drop $100 in a two week period and if you don't have enough metal in a pool account to lock in prices you end up working at a loss.
Small refiners and even jewelers who have a market for their refined metals, are better off in today's metal market to refine in house. Then they can be assured they get a good return and they have the refined metal to work with.
But refining sweeps isn't for everyone, Chris's suggestion to process a small sample is the way to find out.
Small refiners and even jewelers who have a market for their refined metals, are better off in today's metal market to refine in house. Then they can be assured they get a good return and they have the refined metal to work with.
But refining sweeps isn't for everyone, Chris's suggestion to process a small sample is the way to find out.
