It's amazing they used that compound as a herbicide or pesticide (can't remember which) way back in the day. I would Wikipedia it, but I don't want to be put on a list.
How much urea required for neutralizing 10 litre aquaregia solution?
- Thread starter decentdude21
- Start date
Help Support Gold Refining Forum:
- Joined
- Jan 14, 2012
- Messages
- 17
I hope you all do know that what I last posted was an attempt at a joke.
But on a serious note, say I have Aqua Regia with both Silver and Gold in solution. Sulfamic acid has driven out what little if any Nitric remained. PH is @ 1, Stannous test shows definite gold in solution and from doing the process when the gold was enquarted, the gold was alloyed with silver to get below 6K Gold. After filtering that batch, stannous determined that there was gold in solution and yellow cake at the bottom of the beaker, so it was saved. Mixed a new batch of Sodium Nitrate, Hydrochloric and distilled water for the cake. When trying to precipitate the gold from the first batch, should I drop the silver first? or what should I do to reclaim the 52+ grams of pure AG from solution and still retain whatever amount of gold went into solution.
Thanks a million!
Brett
But on a serious note, say I have Aqua Regia with both Silver and Gold in solution. Sulfamic acid has driven out what little if any Nitric remained. PH is @ 1, Stannous test shows definite gold in solution and from doing the process when the gold was enquarted, the gold was alloyed with silver to get below 6K Gold. After filtering that batch, stannous determined that there was gold in solution and yellow cake at the bottom of the beaker, so it was saved. Mixed a new batch of Sodium Nitrate, Hydrochloric and distilled water for the cake. When trying to precipitate the gold from the first batch, should I drop the silver first? or what should I do to reclaim the 52+ grams of pure AG from solution and still retain whatever amount of gold went into solution.
Thanks a million!
Brett
You will not have gold and silver together dissolved in the same solution to any extent. One could be soluble and the other insoluble in a solution, but not both as soluble ions to any extent.
Silver can be dissolved in a solution of nitric acid, gold will not dissolve in nitric acid. Silver is normally parted from gold using nitric acid.
Gold will dissolve in the poor man's aqua regia. silver will not be soluble to any extent in a chloride solution, it will normally be a fluffy insoluble white powder.
Silver can be dissolved in a solution of nitric acid, gold will not dissolve in nitric acid. Silver is normally parted from gold using nitric acid.
Gold will dissolve in the poor man's aqua regia. silver will not be soluble to any extent in a chloride solution, it will normally be a fluffy insoluble white powder.
Last edited:
- Joined
- Jan 14, 2012
- Messages
- 17
The one area that I had a concern, was when I dissolved the alloyed gold to make that cake. I used pure silver (52 Grams) as an alloy. When the beaker settled and cooled, I tested for gold in solution (Knowing that the Nitric dissolved all of the silver) and the stannous showed a positive result? False positive?
When you say "Knowing that the Nitric dissolved all of the silver)" this sounds like you parted the gold with nitric acid before dissolving the gold in the poor man's solution, but then again it also sounds in your description as though you dissolve the alloy of both gold and silver in your poor man's aqua regia.
How are you making cakes from a gold alloy? do you bake these cakes?
Without knowing what you have done in your experiment, it is hard to answer a question about the problem you are having with the experiment.
How are you making cakes from a gold alloy? do you bake these cakes?
Without knowing what you have done in your experiment, it is hard to answer a question about the problem you are having with the experiment.
kurtak
Well-known member
Nitric acid alone will not dissolve gold !!!
If you are trying to stannous test a nitric only solution that has silver dissolved in it this is what happens
Stannous is made with HCl - so when you add the stannous/HCl to the silver nitrate the HCl creates silver chloride
Silver chloride is very sensitive to light - so when the AgCl (created by the stannous/HCl) is exposed to light it does what is called photo graying
In other words - when exposed to light - the normally white AgCl will change to a purple/gray/black color
So the purple/gray/black photo graying of the AgCl gives you a false positive test for gold because photo grayed AgCl is in the same color range of a positive stannous test for gold
Therefore - you know that a stannous test on silver nitrate is a false positive because nitric acid (alone) does not dissolve gold
Kurt
Per the bold print (false positive) this is likely what you are seeing
If you are trying to stannous test a nitric only solution that has silver dissolved in it this is what happens
Stannous is made with HCl - so when you add the stannous/HCl to the silver nitrate the HCl creates silver chloride
Silver chloride is very sensitive to light - so when the AgCl (created by the stannous/HCl) is exposed to light it does what is called photo graying
In other words - when exposed to light - the normally white AgCl will change to a purple/gray/black color
So the purple/gray/black photo graying of the AgCl gives you a false positive test for gold because photo grayed AgCl is in the same color range of a positive stannous test for gold
Therefore - you know that a stannous test on silver nitrate is a false positive because nitric acid (alone) does not dissolve gold
Kurt
Barthel732
Well-known member
I watch all these videos on YouTube where people do use urea and it works fine for them. I don’t understand that honestly. I get that it messes with the ph but if it works for some people what’s the big deal
- Joined
- Aug 12, 2021
- Messages
- 1,355
If you are going to do a job half assed, then it shows in your craft. I, as well as others on this forum, prefer to do things to the Nth degree, IE the best that can be done. If you don't mind half assed, that is your choice. Or you can follow the good advice here regarding chemistry, safety, waste disposal, and many other subjects relative to refining. This better policy adoption, will have additional benefits, that will show up in other aspects of your life. The choice is yours. Don't forget that Youtube is not always based on best practices. It is designed as an entertainment platform, with the sole intent of videos is to get subscribers, which in the end creates money for them. I don't have a definitive number, but from what I have seen, there is a LOT of just plain BS.
Barthel732
Well-known member
I’m not disagreeing with anyone on here. I was just saying that everyone mainly says urea doesn’t work but for a lot of people it does. It doesn’t work for me that’s for sure and I have sulfamic acid coming this week. I was just curious while I’m educating myself more. You are 100% right on YouTube for entertainment. I have definitely learned more from this forum that any video I have watched.
In the past nobody had heard about Sulfamic acid for this use.
All they had was Urea, which works but with some draw backs.
It is not complete, where Sulfamic takes care of the Nitric, Nitrates and the NOx, Urea only converts Nitric to Urea Nitrate.
Which in turn may be another draw back since Urea Nitrate in certain circumstances can explode.
And of course the Urea lifts the pH and if one use too much it might make the Gold hard to precipitate
or even drop out Hydroxides if you get too hard handed with it.
Barthel732
Well-known member
Ok got it. Now yesterday I mixed an inch and a half of Hal with half inch of nitric. I dissolved about 40 grams of gold plated pins and everything went good with that process. I filtered it then checked the ph which was at 1 so I added smb and now I have this grey precipitation any clue what that is. I used stumpout as smb
You have obviously not read and studied enough.
We recommend dissolving the base metals in the pins first.
Then when we use AR we add enough HCl and then Nitric by the drop.
It seems you have dissolved some solder ( grey paste) and when you add SMB it is a massive surplus of Nitric so it redissolves immediately.
And inch and a half of Hal? Or did you mean HCl?
Assuming you meant HCl, an inch and a half. Mixed that with half an inch of nitric. Measuring in inch’s is a bit odd but OK. That would make roughly 3 to 1 AR. Not really recommended as it leaves an excess of nitric very often. Still it was a measured amount. You even checked the PH and it was at 1, that’s good. No mention of the nitric conditions at this point but went straight to SMB, and no mention of the amount used as well.
The devil is in the details is an old saying around here, meaning to do it right requires paying attention to every detail, even the smallest of them.
Barthel732
Well-known member
I actually did dissolve them in nitric first. Just forgot to mention it
View attachment IMG_4193.MOV
So the 40 grams was foils?
Barthel732
Well-known member
I gotta get better at describing my processes. The inches thing yeah it’s easier for me to describe. I’ll go back thru my process and get back to you. My apologies
Barthel732
Well-known member
Sorry it was 40 grams of pins I put into the nitric first. I didn’t weigh the yield after the nitric and base metals. I gotta get better at describing things and details.
kurtak
Well-known member
Generally speaking & for the most part one pound of pins will give you (about) 1.5 grams of gold foils - if they are fully plated pins
One pound = 454 grams so if you divide that by your 40 grams of pins you get 11.35
If you then divide the 1.5 grams of expected gold from a pound of pins by the 11.35 it means you can only expect about 0.13 of a gram of gold from your 40 grams of pins
so call it about a tenth of a gram of gold from 40 grams of pins = about $6
You likely spent more then $6 on your chemical - plus your time & the toxic waste you created that you now have to clean up to make safe for disposal
also - one tenth of a gram of gold is so little that you would hardly see it as a fine dust in the bottom of your beaker - you would/will have a hard time getting it collected together & out of your beaker for melting
As it is - IF (the big if) you did actually manage to precipitate gold from your solution - it is now tied up in all that other junk that is now in the bottom of your beaker --- good luck trying to get that $6 worth of gold back out of the mess you just created
If I were you - I would right this one off as a failed/lost experiment (part of the learning curve for refining)
You next learning curve is to learn how to clean up the toxic mess you just created
Then start doing more research about refining processes - good place to start with that is to read the book by C. M. Hokes - it's available here on the forum
While reading Hokes & other research (here on the forum) concerning refining collect MORE material to try again
When you are ready to try again you want at LEAST one pound of pins &/or fingers so that at the end of the process you actually have enough gold to see & work with
Kurt
Well I'm back home and on my computer now.
I find this whole scenario quite ironic.
You post in this thread asking why Urea is not recommended since it works,
Then you overuse the Nitric by a "mile" and do not denox what so ever.
First this post should have been in an appropriate thread.
Secondly you should have presented a plan which we could adjust as needed.
Now a few questions.
Did you wash and clean the foils after the Nitric leach?
Did you test with Stannous?
What happened when you added the SMB?
In perfect conditions you wold have seen your Gold as a very fine dust on the bottom of the beaker in a day or so.
But since you have an overload of Nitric you could test it with Stannous now.
Give a feed back of the result please.
Definitely, chemistry is a science and happens after the laws of nature.
Nothing we can do about that other than be exact and precise in all we do, even in our description.
