Recovering my first failure - for the science.

[jason_recliner]

Next time I get my hands on a bunch of golden e-parts, I know I'll have a much better clue - thanks to this forum. I've learned some good stuff here about what not to do.

Alas I still need to recover my recovered gold. It's for the science. I've already spent heaps of time and money on gold of probably lesser value than my chemicals. I think it will be one of the best experiences, learning to recover my first failure by not throwing it all out. In the recover/refine process, I call this re-recovery.

Ok, what have I done? Don't slap me, here goes.

Started with memory sticks, CPUs and various fingers and pins. All trimmed as closely as possible.
Approx 3:1 all up of 32% hardware store HCl with 3% H2O2 to dissolve the copper and whatever else AP will make disappear. (I'm still not sold either way whether this will dissolve some gold as well. ??)
Filtered off the green liquid and rinsed (with filtered drinking water, probably unnecessary. I picked up Harold's tip about things that just won't stick in your gold.) all the bits left behind through the same filter.
This leaves me with bits of phenolic board, plastic and gold flakes, dust etc.
I then dumped this in HCl and added home made Sodium Nitrate. I think this is what you mean by "Poor Man's AR". I put the filter in the mix too, to collect even any dust left behind. Finally, filtered out the junk and rinsed everything into my batch with a little more water.
How much NaNO3? Way too freaking much, probably for even 10 times the gold. Good old "Nothing's happening in only 2 hours, let's add more".

I have a nice jar of perfectly clear gold bearing yellow acid, containing a whole lot more chemicals than was ever required.


I also have a separate batch, a small amount of gold-with-a-tough-of-copper bearing light green liquid.
Similarly too damn much NaNO3. Failed to see any result on a Stannous Chloride test, due to excessive nitrate no doubt, even though I know there's (a little) gold in them thar green. Dumping copious qtys of pre-dissolved Sodium Metabisulphite has produced a very small amount of light brown powder sediment. Barely enough to collect, and not enough for the input qty, I think. Let's perhaps ignore this batch for now.

----

Batch #1 "yellow stuff" has a hard time testing positive with Stannous, but it will eventually go a purple to black colour after some time. (Oooh, them nitrates!)
To re-recovery: I have had the yellow stuff on and off a coffee maker for a while, reducing its liquid volume. I intend to slowly evaporate it out. It steams away gently and the jar is too hot to hold after about 10 seconds, which I think is just perfectly slow enough.
I'm now getting clear / white crystals forming under the still quite low viscosity liquid. Presumably this is my sodium nitrate coming back to haunt me. Or maybe could it be table salt, NaCl?

Also, and I can't even ask not to be slapped for this, because this is many weeks ago: I don't remember if I already put some SMB in here and failed to get a drop. Or was it only the green one? Or the other batch where the possums spilt all my brown powder? About 90% I think the yellow is completely SMB free but can't be entirely sure. If I can find something to resemble a test tube, I'll take a small sample and SMB it up to see what happens. I will have to start writing everything down.

It seems that I should keep evaporating my jar until it's a syrupy liquid, and I'll be at that point within a few days. But I'm not sure when to stop; how thick. Then I should obviously filter off the solids, maybe wash the filter back into the jar with a bit of HCl and evaporate again. But then I'm a bit stuck. And I don't have any more gold right now to put in it for nitrates to eat. I'd appreciate any advice.

I read a post a couple of days ago about getting rid of nitrate salts, but I can't find it again in the 1000+ search results.

Again, this is not going to be for the $0.02 of metal returned but for the $1M experience gained.

 

[Pantherlikher]

Hi...
Unless you have a photographic memmory or can read and reread something extremely fast and retain it, You are in way over your head.

How long have you been here? And how much have you read? Have you read enough of Hoke's book to have learned how to remove free nitric acid? Aparently not as you asked about it.

Doing 2 different batches and not knowing what you did to each is a sure sign you need to stop doing and read up and learn what to do from start to finish.

You filtered everything instead of decanted. This is important later as you will clog the filter and wonder why you have liquid that wont go through.

Please stop guessing and start reading. I hate it as well so you are not alone but it needs to be done so you and I am successful and get ALL the PMs in hand.

B.S.

 

[jason_recliner]

Yes you're completely right. When I started each of these I had no clue what I was doing at all. I have been here reading since just a few weeks ago, having makes these blunders just a few more weeks ago. I'm grateful that I've learned so much here already, but know I still have far to go.

My understanding from reading both Hoke and these forums is that there are three main ways of removing excess nitric. Namely,
- add more gold
- evaporate
- Sufamic acid, which converts excess NO3 to SO2

I don't have more gold. And I'm loathed to start adding more chemicals and foul it up more. I can't find anything about how much to add. And I don't know how much nitric I have. So evaporation looks like the clear winner.
However, it's a little foggy to me when they're also still dissolved in a salt form, rather than as free nitric acid.

 

[g_axelsson]

In a solution the different atoms in the nitrate or chloride salt doesn't stick together. You can't say which nitrate ion that belongs to a metal ion. The same thing goes for the protons and acid molecules, they split up.
In this soup the nitrate ions sees the protons from the hydrochloric acid and by all practical means forms nitric acid together with a dissolved chloride salt.

When you evaporate this mix the parts that can turn into gas will do it in different rates depending on a number of factors, mostly how concentrated the mix is. You get water, HCl and HNO₃ as vapors. But the mix must be balanced, you can't remove only the nitrate ion and not send a proton with it. The same goes for the metal salts, you must balance out every positive metal ion with a negative Cl or NO₃ ion.
When the concentration of the salts becomes higher than the solution can hold both nitrate and chloride salts starts to crystallize out of the solution. When you add HCl to this metal salt mix then you add more Cl ions, the next evaporation stage will remove more mixed HCl and HNO₃. Since you don't fill up with new nitrate ions you get less and less nitrate ions left until the mix is denoxed and all the salts are turned into chloride salts. Repeat until the nitrate ions are out of the solution.

The salt is a problem when doing poor mans AR, it locks nitrate ions in the salts and makes it a lot harder to get the nitrate ions out of the solution. It is much easier when using nitric acid as there are no extra metal salts added to the mix.

I don't know if it is a bit clearer why not all the nitrate salt can exist as free nitric acid, don't know if I can give a better explanation.

Göran

 

[butcher]

Jason,
This is not easy to explain, I will try.

Gold will not react with nitrate salts, example if we evaporated a solution of sodium nitrate with gold we would be left with sodium nitrate crystals and our button of gold.

Many metal nitrate salts will concentrate on evaporation, (example sodium nitrate, potassium nitrate, copper nitrate, and many other nitrate metals salts...), during evaporation these metal nitrate salts will not decompose to gas like nitric acid will, (unless the nitrates have metals in solution to react with, or are converted to other forms of gases with acids like HCl in solution), take one of the metal nitrate salts for example; copper nitrate you can evaporate a solution of copper nitrate to relatively dry crystals of copper nitrate, and then you would have to heat these copper salts to a high temperature before you would decompose the nitrate anion portion to gas and leaving you with copper oxide powders from the reaction of the high heat and air, the point here is you could not remove the nitrates or salts of metal nitrates in solution through evaporation alone.

We can convert the nitrate salts to chloride salts, lets say we have copper nitrate in solution, and we evaporated it to a concentrated solution, now we add HCl to this concentrated copper nitrate, forming a form aqua regia with this copper in solution, now we evaporate off gases through concentration of this solution, with the acid HCl added the nitrate anion from the copper forms several gases, some leave the solution fairly easily with time, and some we will remove through evaporation, during this process much of the copper is taking on the chloride anion from solution giving up its nitrate anion, which is being removed from solution through evaporation, upon getting the solution concentrated, we may have convert most of the copper to chlorides, driving off the nitrates, but we may still have some unconverted copper nitrate salts, so we may have to repeat this several times.

If you used a little excess nitrates to dissolve your gold, the evaporation method (with HCl) can work to remove the small amount of excess nitrates, but if you used way way to much sodium nitrate, evaporation alone may not be the best way to solve this problem.

Sulfamic acid will react with nitrous acid or nitric acid, giving nitrogen gas or nitrous oxide gas and sulfuric acid;
HNO2 + H3NSO3 --> H2SO4 + N2 + H2O
HNO3 + H3NSO3 --> H2SO4 + N2O + H2O

Sulfamic acid can be written with more than one formula, H3NSO3 (or) HSO3NH2

Sodium nitrite reacts in solution with an excess sulfamic acid to form, sodium bisulfate and nitrogen gas;
NaNO2 + HSO3NH2 --> NaHSO4 + N2(g) + H2O
or
NaNO2 + H3NSO3 --> NaHSO4 + N2(g) + H2O

I am not completely sure of the reaction of a solution of sodium nitrate with a solution of sulfamic acid, my guess is that it forms the bisulfate and nitrous acid:
suspected reaction ???
NaNO3 + H3NSO3 --> NaHSO4 + N2O(g) + H2O ???

Note the acidic sulfate salt can react with base metals on evaporation to form base metal sulfates, (bisulfate in solution can act like sulfuric acid) or metal sulfate salts, luckily most sulfate salts are soluble.



Some more thoughts on this subject.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=37&t=4517&view=next

With the use of too much sodium or potassium nitrate salts in a solution of poor-mans aqua regia, there may be a few ways to deal with the problem, and as we know base metals in solution always complicate these problems, having excess acid would be important part for solving this problem, which can help to convert the salts to acids, or react with base-metals in solution, where we can decompose the acids as gases with heat, or convert the base metal salts to another form of salt with heat or evaporation...

When you have too much contamination in a solution of gold, whether it is a contamination of metals or salts of other chemicals as in this case way too much sodium nitrate, you may be better off cementing the gold from solution using copper, being sure to have enough acid in solution during the cementation process.

Best approach, it is best to learn how much is needed, and only use as much as needed, over use of acids or chemicals can give us many problems to deal with later.

 

[Palladium]

Copper is your friend in this situation. Cement the values and start the process over.

 

[nh6886]

What a great thread!
I don't have anything to add to fix your problem, I would do just what Butcher and Palldium said and cement the values with copper and start over, that's why I'm a better refiner than carpenter.
I did have to comment on Butcher's fine explanation of how the sulfamic is removing free nitric from the solution, I will add that to my notebook.
The reason for my post though was Göran's post. I have used evaporation mostly in the acquaintance experiments and I could have repeated it from memory after reading it dozens of times here on the forum. That being true I had never visualized it taking place until I just read your post. Thank you for posting that, it has to be one of the better word picture I have ever read.

All the Best,
John

 

[jason_recliner]

Such great advice! Thank you everyone. I've spent about an hour going over your answers and links in the hope to not do something stupid.

Even though it sounds like cementing is the general consensus, evaporating would probably be my preferred option as I believe it's already a copper free solution. (Even though not to you top guys' standards) Starting again with copper can always be plan B. And I will learn more this way.

I'm certainly more glad I didn't try the sulfamic now, if even the experienced folk are not familiar with the chemistry.

If I understand correctly, repeatedly adding HCl and evaporating will actually slowly get rid of my salts.

When the concentration of the salts becomes higher than the solution can hold both nitrate and chloride salts starts to crystallize out of the solution

Physically removing all salt crystals possible would be the best start. Unless some of those chloride salts could be a form of gold chloride? Or is that a stupid thought?

Each time would convert a bit more nitric salt into nitric acid. Hoke speaks of adding HCl to get rid of free nitric acid. I think I understand that bit. So then I could keep doing HCl/evaporate over and over until it's clean. It is meant to fume brown, but my HCl is only 32% so I don't know whether to expect the same reaction.

There's something I found interesting during the first evaporation so far. When it was 'boiled' down to maybe 60% original volume, I started seeing crystals. These kept forming only until about 30% or so but have not increased much now that It's down to maybe 10% original liquid volume (yeah, it was pretty thin) and now like a cheap, watery honey. This suggests that as I was getting rid of water and acid that maybe the water went out first. ?? And that the acid doesn't hold the salts so well as water. ??

Finally, Hoke mentions to never let it run completely dry. Does anyone have an analogous suggestion of how thick to let it evaporate?

Again, my grateful thanks. I feel I'm getting a better handle on it.

 

[solar_plasma]

Jason wrote:

I'm certainly more glad I didn't try the sulfamic now, if even the experienced folk are not familiar with the chemistry.

Where did you read that the experienced folks are not familar with sulfamic's chemistry?

 

[Reno Chris]

Even though it sounds like cementing is the general consensus, evaporating would probably be my preferred option

Ignoring what experienced folks are suggesting and doing what you thought was best is exactly what got you into this problem in the first place! There are all kinds of threads on this forum that go along the line of "I threw everything in a bucket and added acid, now I have a mess" - just like yours. Over and over the experienced guys say you shouldn't do that to the folks who have done it. But that's what you did.
Now the experienced guys are suggesting your cement everything out and start over - but again you are not going to do as they suggest, you are going to do what you think is best.

Good Luck!

 

[jason_recliner]

Where did you read that the experienced folks are not familar with sulfamic's chemistry?

Here:

I am not completely sure of the reaction of a solution of sodium nitrate with a solution of sulfamic acid, my guess is that it forms the bisulfate and nitrous acid:
suspected reaction ???
NaNO3 + H3NSO3 --> NaHSO4 + N2O(g) + H2O ???

From what I read, I rate Butcher as one of the more experienced here.

Ignoring what experienced folks are suggesting and doing what you thought was best is exactly what got you into this problem in the first place!

Respectfully, I kind of expected someone to say this. I hoped you would not think that I was so arrogant as to completely ignore what experienced folks say. No, not doing that. I read and reread everything everyone said until I could picture the entire process from salt to melting. I don't understand all of the reactions that Butcher explained, but the ones that count for me I believe I now do.
From your collective replies, which by the way were really helpful and positive, I gleaned that there were two methods that would work. One would be simpler but to me would mean almost abandoning my recovery work so far. Which, if necessary, fine. The other more involved and time consuming but I don't have to further contaminate what I have with more metals. And if I take it on with the proper care and precision, I would learn so much more. Which ultimately, is the aim. If on the other hand it all turns pear shaped, I've still got cementing as an option. Win-win!

 

[Pantherlikher]

Great idea wanting to learn from your mistakes.
Are you ever going to make this 1 mistake again? Probably not.
So what is it you intend to learn?

You simply made a mess and the "experienced guys" have said what they would do to correct it.

I see you playing with a stock pot issue and reinventing the wheel on how to process it. Stock pot is where everything goes and gets PMs extracted using copper. Then the solution moves on to drop copper and then on to drop all metals and rendur the solution safe for disposal.

If you wish to experiment, I would say to start fresh and read about mixing the chemicals in question to find out what happens and why.
The why is what is learn.

So what will you gain by trying to "do it your way"?

B.S.
...Every experiment is based on a clear question and extensive research to obtain a process of tests to gain unknown results...

 

[butcher]

Jason,
Cementing values from solution will not really add more contaminates, or at least more than can easily be dealt with, you may end up with an impure gold, but this recovered gold can easily be refined, at this point you have several contaminates in solution, that without a good understanding of how to overcome the problem would be harder to recover your gold from, using copper to cement values will leave base metals and salts in solution, if kept acidic during the process will consume the oxidizer, yes you will most likely put more copper into solution as your gold cements out, and if done right, large clean copper buss bar, you will have basically little or no copper mixed with your impure gold, if you use copper in other forms, like thin copper metal or powders you may get more copper mixed with the gold as the copper metal may not get consumed, or the thin copper dissolves unevenly dropping pieces of metal off the sheet, where the thick bar of copper would not.

Jason,
At this point you need to concentrate on recovery of the gold from solution, with a contaminated solution trying to follow through with refining gone wrong, would not be an easy method to follow through with, without a much better understanding, of these problems involved.

Your chances of getting your gold from this solution are best with cementing on copper, trying to deal with these extra, nitrate salts and other contaminates, at this stage of your learning process may prove more than you can deal with, and make little sense to try.

Recovery of the gold using copper in your case is a no brainer, it leaves behind most of your problems behind, and sets you up in a position to refine your impure gold.

I normally find gold needs to be recovered, and refined twice, I see you as still being in the recovery stage (but trying to recover and refine it in one step which would not work well for you in my humble opinion).

I am learning like evey one else here, and I will be learning the rest of my life, I do not know all of the chemical reactions going on in solution, I am not a chemist, (although I have been studying the chemistry of metals), I also doubt even professional chemist can say for definite he know all of the reactions going on with metals in different mixtures of solution, he may have an educated guess, and be able to write an equation for that reaction, but in actual chemistry these reactions get very complicated, as far as the sulfamic reaction with nitrate, I was unsure of, I could not find an Known equation written for it, I used an educated guess from the reactions of the other known reactions and how they reacted) and balanced the formula using this educated guess, much like the professional chemist would do, but until I can find a more definite source for this formula I will put my educated guess in question marks, untill I know better.

 

[Palladium]

I normally find gold needs to be recovered, and refined twice, I see you as still being in the recovery stage (but trying to recover and refine it in one step which would not work well for you in my humble opinion).

I think people misunderstand what we do as gold refiners. 99% of our time is spent recovering gold and only about 1% is spent actually refining it.

 

[glorycloud]

I think people misunderstand what we do as gold refiners. 99% of our time is spent recovering gold and only about 1% is spent actually refining it.[/quote]

Well said!! 8)

 

[jason_recliner]

Thanks for the advice everyone. I've worked out that my yellow batch had no SMB in it, just too much sodium nitrate. I have actually gone my own way and done Hoke's evporation, only because cementing with copper was always there as a backup. It's added to the experience. Cementing with copper may have been faster. But I am in it for the SCIENCE!

What I found is that as I would evaporate it down, the hue would change from bright yellow "pineapple cordial" to a darker, almost brown, sort of "morning after a big night" colour, if you don't mind the visual image.
Hoke warns about letting it dry out, but texta lines on the jar showed that as it neared the bottom it would really slow down (1/4 rate) anyway. I didn't get that close.

At that point, there'd be salt in the bottom. So I filtered it into a clean jar and washed the granules with a bit of HCl until they were white. Obviously this washes a bit of that NaNO3 back into the mix, but prevents loss of gold. This took three full runs. Adding more HCl, it would go back to bright yellow.

Something confuses me a little. My coffee maker gets it to about 80°C and it has a very gentle steaming effect. Barely even visible steaming, it would be good to have 5-10° hotter. Some of the steam gathers on the cooler top of the jar, a little like reflux distillation. I swab these watery beads and stannous test them; to my comfort: no gold. I let the reduced acid cool completely to the ambient 15°C before putting it away for the night, lid on, outside on the rear porch. Obviously I don't want it fuming off in my house. The jar is now maybe 10% full. It gets down to maybe 7-10°C overnight. I come back the next day and there's a thick yellow syrup in the jar's thread and even several drops on the porch surface. :shock: ??!!
How does this happen? My background is electronics, not distillation. But it's got me.

Moving on now, I've added SMB. This time, unlike my first time, I have predissolved my SMB to avoid SMB powder in the gold. Someone suggested keeping excess tin in the stannous and that reflects my sediments with the jar of SMB.

I am delighted to announce that I got an almost perfect drop! I watered down my yellow 4:1 into the tallest thinnest jar I could find. As I injected SMB solution it instantly turned into a brown cloud. A week to settle and there's now a mid-brown powder layer on the bottom but the liquid still has a slightly yellowy brown tinge. I've added a little more SMB today but I don't really know when to stop. I'll give it a few more days to settle again before hitting it with a stannous test. Spare centrifuge, anyone? :idea:

I'd like to reiterate that I've not ignored anything that anyone has said, even though I chose a different path for one of the batches. I have weighed your advice thoughtfully towards my own situation. And by asking the question, Butcher has preventing me doing something stupid; namely adding sulphamic acid where it's not appropriate. My other green test batch will definitely have to be cemented, but I'll see what else gold I can add to it first. It's got way too much HCl and NaNO3 in it, and stuff-all gold.

 

[g_axelsson]

I let the reduced acid cool completely to the ambient 15°C before putting it away for the night, lid on, outside on the rear porch. Obviously I don't want it fuming off in my house. The jar is now maybe 10% full. It gets down to maybe 7-10°C overnight. I come back the next day and there's a thick yellow syrup in the jar's thread and even several drops on the porch surface. :shock: ??!!
How does this happen? My background is electronics, not distillation. But it's got me.

Is the lid made out of steel? As the temperatures drop during the night the lid cools faster than the fluid and some acid condenses on the lid and reacts with the metal.

I don't use metal lids on jars, I usually just wrap it in plastic foil and press the center portion down a bit for condensation to drip in the center and not go to the outside. It also protects against any high pressure building up if things starts to react.

Another tip, get an evaporating dish for doing evaporation. Any wide jar with low edges works. That way you don't get as much condensation on the edges of your vessel. Any condensation drops back and needs to be evaporated again. The higher and more narrow your vessel are the slower it will evaporate.

And lastly, if you have added SMB to a solution and wonder if you need more, just test it with stannous. But beware, too much SMB could give you a false positive test with a brown coloration, not a purple one.

For your left over liquids after dropping the gold, do a search for "stock pot" and also read about it in Hoke.

Göran

 

[jason_recliner]

I let the reduced acid cool completely to the ambient 15°C before putting it away for the night, lid on, outside on the rear porch. Obviously I don't want it fuming off in my house. The jar is now maybe 10% full. It gets down to maybe 7-10°C overnight. I come back the next day and there's a thick yellow syrup in the jar's thread and even several drops on the porch surface. :shock: ??!!
How does this happen? My background is electronics, not distillation. But it's got me.

Is the lid made out of steel? As the temperatures drop during the night the lid cools faster than the fluid and some acid condenses on the lid and reacts with the metal.

I don't use metal lids on jars, I usually just wrap it in plastic foil and press the center portion down a bit for condensation to drip in the center and not go to the outside. It also protects against any high pressure building up if things starts to react.

Yes, it is metal! Thanks. I'll ditch it for Glad wrap in future.

Another tip, get an evaporating dish for doing evaporation. Any wide jar with low edges works. That way you don't get as much condensation on the edges of your vessel. Any condensation drops back and needs to be evaporated again. The higher and more narrow your vessel are the slower it will evaporate.

I'm constantly on the lookout for something better than I currently have, but that still fits the Jason Recliner coffee maker. The best so far is Doritos salsa jars (sans supplied metal lids), though they are a square profile and therefore don't lend themselves to optimal evaporation. I found some wide, glazed bowls in Safeway, but they have tall base rings and are not conducive to great thermal conduction. Ideally, if I get the NaNO3 portion right in future, I shan't need to evaporate at all.

And lastly, if you have added SMB to a solution and wonder if you need more, just test it with stannous. But beware, too much SMB could give you a false positive test with a brown coloration, not a purple one.

For your left over liquids after dropping the gold, do a search for "stock pot" and also read about it in Hoke.

Göran

Awesome. That's just what I was hoping would be the right thing to do. Thank you kindly.