But i know for a fact that there is gold in it. So this is some background about this solution. I put a pound of ram gold fingers in my Ap solution that has been resuseda time or two. And since i haven't had the opportunity to extract the copper from my ap. All i have been doing before reusing the ap is running air thru it and adding fresh muriatic acid and hydrogen peroxide. With that being said. After i gathered all my gold foils. I put them in a beaker. Then I decided to also throw a couple other filters with other small amounts of gold that I have collected in small tests of other things such as gold-plated pins that I deplated with hot HCL, as well as another random filter that had some gold on it, but from where i do not remember. But all of which did indeed have gold on them. I dissolved with ar been filtered. Then Filtered the solids out. But when tested with stannous chloride i get negative results. I know there is gold in there. But now im thinking my solution either has silver or copper or some other metal that is making my Stannous give a false negative result. Here's a pic. Please help.
Negative test result for gold in solution
- Thread starter Rreyes097
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jason_recliner
Well-known member
First up: when you reuse AP and actively pump air through it, there is utterly no need whatsoever to add peroxide. It may lead to unwanted dissolution of gold before you're ready to process your foils.
Now, your AR: did you add your nitric incrementally, in tiny amounts, allowing time for it to work? Little doubt there is gold in there, but if you have used too much nitric, you may not get a positive test. This is because as soon as it forms a colloid (purple), it re-dissolves... which has been discussed many times. Ag and Cu will not prevent a positive result. (Ag will not be in solution in AR anyway.)
Based on your description, you probably need to start denoxxing through sulfamic, Hoke's evaporation or cementing on copper.
Attaching your picture may help us gauge by the colour, which is best.
An idea how much gold is in how much solution, and how much nitric was added, might also be helpful.
Now, your AR: did you add your nitric incrementally, in tiny amounts, allowing time for it to work? Little doubt there is gold in there, but if you have used too much nitric, you may not get a positive test. This is because as soon as it forms a colloid (purple), it re-dissolves... which has been discussed many times. Ag and Cu will not prevent a positive result. (Ag will not be in solution in AR anyway.)
Based on your description, you probably need to start denoxxing through sulfamic, Hoke's evaporation or cementing on copper.
Attaching your picture may help us gauge by the colour, which is best.
An idea how much gold is in how much solution, and how much nitric was added, might also be helpful.
As Jason stated plus test your stannous to check it hasn't gone bad, it happens.
Whenever you test a new solution you should always have a standard to check that the stannous is active, keep a small sample of gold chloride on hand to test with.
Edited for clarity.
Whenever you test a new solution you should always have a standard to check that the stannous is active, keep a small sample of gold chloride on hand to test with.
Edited for clarity.
Thought i attached the pic. As for nitric i used the premixed ar. I know it's not the best option but wanted to use it up before any shelf life it has is expired. So what are your thoughts after looking at the pic of the solution ? What could be giving me the false neg? It definitely could be that my Stannous is expired although it worked fine 6-7 days ago. So i will be mixing a new stannous shortly. I just didn't want to put urea into solution then smb without asking some questions. Thanks for your advice!
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You likely still have quite a bit of nitric left from the premixed AR. When your stannous reduces the gold to the purple colloid the nitric allows the gold to redissolve as fast as it is reduced. Hence no purple stain even though you saw the gold foils dissolve into the solution.
You could add more gold foils or small button until the reaction stops and they no longer dissolve. Then you know all the nitric has been used. Add a little HCl just to be sure the reaction didn't stop due to a lack of it instead of nitric.
You could use evaporation as outlined in Hoke.
You could still have a lot of nitric left, so sulfamic could react quite vigorously causing a boil over and loss of gold.
I think I would opt to cement with copper.
If you are going to use this premixed AR, I would think you would be better off to start with your foils in just HCl. Then add the AR incrementally like you would with nitric. Then you can stop adding when you get to the last of the foils so you don't end up with excess nitric to deal with.
You could add more gold foils or small button until the reaction stops and they no longer dissolve. Then you know all the nitric has been used. Add a little HCl just to be sure the reaction didn't stop due to a lack of it instead of nitric.
You could use evaporation as outlined in Hoke.
You could still have a lot of nitric left, so sulfamic could react quite vigorously causing a boil over and loss of gold.
I think I would opt to cement with copper.
If you are going to use this premixed AR, I would think you would be better off to start with your foils in just HCl. Then add the AR incrementally like you would with nitric. Then you can stop adding when you get to the last of the foils so you don't end up with excess nitric to deal with.
Thanks so much. That was what i thought was going on but i was just worried because my first attempts at using ar with various material and little to no knowledge i ended up with solutions with gold trapped and i had feared this was the case again. I appreciate the time everyone put in with their knowledge. Im done with this premixed AR because this isn't the only issue ive had with this. I believe it is also responsible for my solution redisolving the dropped gold even after i have used urea and then dropped with smb. Ill put solution in water rinse then warm HCL to get rid of any remaining base metals. Next thing i know solution is again testing positive for gold via stannous! :x
jason_recliner
Well-known member
Yes. It's exactly the same effect.
The more dilute your solution, the slower this will happen, but it will keep happening as long as you have any excess nitric at all.
If you want a quick fix for all your solutions simply cement them with copper and refine them again using the minimum amount of AR for the powders.
upcyclist
Well-known member
That's an excellent point. Another way to do it, preserving your investment in premade AR at the cost of time:UncleBenBen said:
1. Use about half as much premade AR as you think you need.
2. When the reaction slows, add HCl to kick off the reaction again (remember, "too much nitric in the premade" = "not enough HCl in the premade")
3. When adding more HCl doesn't rejuvenate the reaction, add more nitric.
Repeat steps 2 & 3 as needed. About the time you get a feel for how much extra HCl you need to balance out your premade, you'll be out of premade AR
--Eric
upcyclist
Well-known member
Simpler thought: If you don't mind possibly using too much HCl (since it's relatively inexpensive), you could just cut your premade AR in half with HCl. Add extra nitric as necessary.
I really do not understand the chemistry but prepared AR loses its potency, not sure if it's contact with air but it happens, my advice to anyone is to add excess HCl to the material then slowly add nitric or nitrates to complete the reaction.
