# My gold flake dissolved in muriatic acid!



## yvonbug (Sep 6, 2009)

I was cleaning up some gold that had the blue goo in it by heating up some muriatic acid and putting it in it. It usually cleans it up. But I guess I left it on the hotplate too long cuz the gold flake disappeared. How do I "drop" it out of the muriatic? This has happened a couple of times with different types of original materials. Help! Thanks, Yvonne


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## Juan Manuel Arcos Frank (Sep 6, 2009)

Yvonbug:

I have got bad news for you.....muriatic acid does not dissolve gold so your gold flake was not gold.Can you see gold foils in your solution?How did you get your gold flake?.

Regards

Manuel


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## yvonbug (Sep 6, 2009)

Well, some came from some connector pins, some came from backboard pins, some from gold fingers, some from RF connectors, all came from stuff I got in the '80's. From silicon valley. And I have processed the very same stuff before and made beautiful buttons out of it. What I haven't done before is to let it sit so long on the hotplate. I know muriatic doesn't dissolve gold. Could it have broken down so much that I just can't see it with the naked eye? The muriatic is very yellow, but it gets real yellow anyways when I do this. And I haven't thrown away any solutions, just in case, cuz I know that what you put in, will be there. Only garbage I've ever dealt with is the "blue goo".


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## Palladium (Sep 6, 2009)

Since it was boiled for an extended period of time i wonder if the rapid boiling action and agitation would have stirred enough oxygen into the solution that it might have dissolved. Heat is a type of chemical energy input which might just have done that since the flake or foils are so thin. Wouldn't work on thick material, but might dissolve the thin foils. 

I need to research this avenue. I would say yes it's possible to an extent that even a small amount of gold will dissolve in Hcl, but how much would dissolve is a different story.


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## Juan Manuel Arcos Frank (Sep 6, 2009)

Well,try the stannous chloride test for gold...CLOROX method dissolves gold...tap water in some countries have enough chlorine dissolved.Muriatic acid and chlorine in tap water can dissolve gold.
Hope it helps.
Manuel


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## yvonbug (Sep 6, 2009)

It was just small amounts. So, how do I get it back out?


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## Oz (Sep 6, 2009)

I routinely dissolve once refined gold powder precipitates in straight HCl on a hot stir plate when it is dirty instead of using nitric that must be evaporated away before re-precipitating. HCl only needs an oxidizer to put gold into solution and normal air chopped in suffices much as a bubbler works in AP.

I have even had platinum group metals go into solution in straight HCl over an extended period of time as well.

Your gold is now a gold chloride that can be precipitated as usual with SMB.


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## Juan Manuel Arcos Frank (Sep 6, 2009)

Adjust solution´s pH to 1 with urea,then add some SMB...the gold will precipitate but first find out if you have gold in solution using the gold solution detector.Do not throw away anything until you know where your gold is.
Manuel


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## Oz (Sep 6, 2009)

Do not be concerned with having free chlorine interfering with your precipitation as your boiling would have removed it.

I see no need for the urea as no nitric was used.


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## Palladium (Sep 6, 2009)

I've been reading some of the physics involved in this and it get pretty interesting. Acid digestion by microwave is an interesting area.


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## stihl88 (Sep 6, 2009)

Is it possible you added some chlorine to the solution, by means of tap water?


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## eeTHr (Sep 7, 2009)

Yvonne;

If you use dry SMB, instead of dissolving it in water, you will need to add a little water to the very-boiled-down HCl to get it to precipitate.

I tried without any water once, and nothing happened. Then when I added about 5 to 10% (if I remember right) water, it instantly turned to chocolate milk color---maybe a shade or two darker. The next day it had settled out as a dark brown powder Au.


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## Harold_V (Sep 7, 2009)

stihl88 said:


> Is it possible you added some chlorine to the solution, by means of tap water?


I refined gold for more than 20 years, using (chlorinated) tap water routinely. I never experienced even a trace of gold dissolution that could be attributed to chlorine in water. I washed my gold extensively, using HCl and tap water. I would have seen at least minor signs of trouble were that the case. So this has merit, I processed thousands of ounces of gold in my years in the lab. 

Charlene should do the smart thing, which is to dilute the solution, so any crusting is dissolved, then test with stannous chloride. If gold has been dissolved, it will report in the test. I expect that is not the case, but that the gold, being very thin, has broken into miniscule particles that will be found suspended in the solution. 

If the above is not the case, and gold has been dissolved, I'm of the opinion that one should look beyond chlorine to determine why it was dissolved. It's entirely possible something was included, be it inadvertently, or not, that dissolved the gold.

Working blindly is not the smart thing to do. Testing the resulting solution is. 

Harold


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## stihl88 (Sep 7, 2009)

Yeah i messed up the other day when it came to rinsing my AP solution from my fingers batch and instead of filtering and throwing out the AP solution i went straight ahead and added about 1/3rd volume of tap water to the AP solution. When washing my AP solution from the fingers the solution turned milky white then would turn a light yellow color. I discovered this when rinsing back and forth between distilled and tap water. when i washed with the distilled water the solution stayed white, when i washed with tap water it turned a light yellow.


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## Platdigger (Sep 7, 2009)

Yvon, was this "gold in blue goo" from a nitric disolution?


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## markqf1 (Sep 7, 2009)

I would let it sit for a couple of days if it tests negative for gold with stannous.
The particles could be so minute, they would be hard to see otherwise.

Almost impossible to filter too.

Mark


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## yvonbug (Sep 8, 2009)

Wow, so many helpful people! That's why I love this forum! Anyways,Thank-you, oz,for your input. This was streight muriatic acid, no water added. And it was only very warm, not boiling. My hot plate doesn't get that hot. It's just a fancy warming "trivet" kinda thing for casseroles on the buffet table. I like using it because nothing can boil over on it. It just keeps things real hot.Can you precipitate stuff out of plain muriatic? 
Palladium, Got a microwave oven you don't mind wrecking? That should work pretty quick, huh?
stihl88, I get my water from a well, so no chlorine, but I'm sure there are alot of minerals in it, like iron and , uh, well, stuff like that. Heh, Heh.
eeTHr; nice name. I did add some water when I poured all the little jars into one larger jar. I used both well and distilled water when I rinsed the bottles into the one jar. Cuz I was doing them at separate times. It was only 4 little bottles that it happened in. And these little bottles did get left on the hotplate a little longer than usual. So maybe it did brake down alot.
Harold, I don't like to think that I work blindly. And who's Charlene? I've stopped useing distilled water when I'm doing AR. But I still use it when doing Nitric digesting because for some reason it really affects the results. And I'm noticing that "purified" water seems to cut down on the "blue goo" too. weird.
Platdigger; yes, it was from a nitric digest that I got the gold flakes in the "blue goo" from that I was cleaning up in the muriatic acid. 
markqfl, nope, I'm a dummy, but, I still haven't gotten myself any stannous to test with. And after all these years,too.  

Again, thanks for all the suggestions. So, should I try dropping it out with SS? Or adding more water and waiting awhile? It has sat overnite, and not on the hotplate.


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## Anonymous (Sep 8, 2009)

yvonbug Pm me your mailing address, I'll send you some stannous along with a couple of grams of pure tin - on the house. I offered my chems for sale along with my books awhile back - no takers, Rather then discard it would be nice someone gets some use of them.

Best Regards
Gill


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## Harold_V (Sep 8, 2009)

yvonbug said:


> Harold, I don't like to think that I work blindly.


And yet you clearlly stated:



yvonbug said:


> markqfl, nope, I'm a dummy, but, I still haven't gotten myself any stannous to test with. And after all these years,too.


I'm not trying to be rude, just stating fact. In this instance, everything you need to know about the state of your gold can be answered with one simple test, which takes but seconds. I call that working blindly. 



> And who's Charlene?


Sigh! She's the name of the gal I was talking to in my post. The name, obviously, is a figment of my aged imagination. I'm old, so I'm allowed to say stupid things. Maybe you can find it in your heart to forgive me (maybe get some stannous chloride while you're doing it).


> So, should I try dropping it out with SS? Or adding more water and waiting awhile? It has sat overnite, and not on the hotplate.


No, you should do none of the above. What you should do is test the material, using the precise method I suggested earlier. Until you know where your gold is, it makes no sense to do anything. That's what I mean by working blindly. You have no idea where your gold is, or in what form. 

Harold


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## Platdigger (Sep 8, 2009)

So, Yvon, after the nitric digest, you went straight to hcl, without incineration?


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## yvonbug (Sep 8, 2009)

Yeah, heck, I was just trying to clean up some "blue goo"! If I incenerated it, the gold flakes might just burn away, too. ?? :roll:


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## Platdigger (Sep 8, 2009)

If there was any nitric left (in this goo), it would have formed a dilute AR when you added the hcl, disolving your gold.

At this point, the nitric is probably in such a small amount, that you can just dilute it some with water, and precip the gold with smb.


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## yvonbug (Sep 8, 2009)

Now that makes the most sense concerning my situation! The blue goo would very likely have a little nitric in it. But, wait! Uh, When I put the blue goo/ gold flake combo into the muriatic, it was in powdered form. Can the nitric still be affective after it's dried? And it only happened to a few of my batches. The other ones cleaned up nicely. I also didn't leave the other ones on the hot plate so long either.


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## Platdigger (Sep 8, 2009)

Yes, you could have had "nitrates" present in your dry powder.
Which would form a mild AR when you added hcl. The extra time you gave this batch is most likely the reason "all" the gold disolved.
You most likely were disolving some gold in the other batches also.


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## qst42know (Sep 8, 2009)

yvonbug said:


> Yeah, heck, I was just trying to clean up some "blue goo"! If I incenerated it, the gold flakes might just burn away, too. ?? :roll:



Incineration is accomplished well below the melt point of gold 1060C. The boiling point of gold is near 2600C so unless you severely overheat it by more than double it won't go anywhere. 

Crusty voluminous base metal oxides will form and may conceal your gold but the gold remains unharmed.

From this chart you can see there is little risk of approaching the point of losing your gold heated to red hot even in full sunlight in a stainless steel pan.

http://hearth.com/econtent/index.php/wiki/Stainless_Steel/


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## Platdigger (Sep 8, 2009)

In fact, any blue powder was more than likely, copper nitrate.


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## yvonbug (Sep 8, 2009)

All I ever do is e-scrap. The "blue-goo" is actually metastannic acid, or tin paste. What I mean by thinking that my gold foils (flakes) might burn up if I incinerated it, is that I have melted gold foils with a torch before, it being so thin. So I know it can be incinerated and possibly blown away. This is the first time I've ever seen my gold disappear in a muriatic hot wash. But I've cleaned up the blue-goo this way many times before. When all you do is e-scrap you get blue-goo alot. Now, I know my gold is in that muriatic, in that there jar. I know it's there. I just can't see it and I don't know how to get it to re-appear. Enough to filter it, anyways. I'm going to take a little of it and try diluting it a little and try some SS on it. We'll see if that works.


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## lazersteve (Sep 8, 2009)

Y,

If all the solids are all dissolved you can add in a piece of solid copper and cement out the PM's.

Steve


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## markqf1 (Sep 9, 2009)

Sncl2.
It's real easy to make.

Mark


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