Pins With Nitric Acid

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This is what i get - 0.5 grams of gold dust. I am amazed, I didn't expected that much. I had 0.5 grams of dust before aqua regia and then I removed 0.25 grams of white dust thru the filter, so how it is possible that I get 0.5 grams of gold + 0.25 grams of filtered dust from just 0.5 grams of material before aqua regia? 23.jpg
 
butcher said:
Copper metal is not a very reactive metal, this is why it is placed just above the more noble metals in the reactivity series of metals, there it is below hydrogen in this list of reactivity of the metals, because it is not easily attacked by hydrogen from acids (like HCl or H2SO4), copper will not dissolve in dilute sulfuric acid, just like HCl it would need an oxidizer, you can dissolve it in concentrated Hot sulfuric acid where SO2 gas is being formed, but that is just way too dangerous and complicated.

You can add an oxidizer, but at that point I would just use HCl, or even CuCl2, or better yet ferrous chloride, or (the old used "acid peroxide" we normally have lots of waiting to be treated as waste) in a heated reaction this Copper/Iron chloride solution can consume lot of copper, it does take some understanding as to how the copper and iron chloride reacts, to be able to use this to recover the gold, and to separate the copper and iron from this to reuse the copper, as copper chloride, I have made a few posts that may help if someone wishes to try it.

If using sulfuric acid with pins the concentrated sulfuric acid electrolytic cell would be one of the best choices
Click to expand...

So would it be fine to use say ferric chloride to dissolve the copper etc from the pins as a first step, or will it also dissolve some of the gold flake?
I do electronics by trade and have used different etching solutions like (hydrochloric / H2O2) but have never gave much thought to gold it that respective.
Your answers are very helpful to beginners like me and I thank you. To understand the pitfalls of separating gold from the pins, what other then the AquaRegia (hydrochloric/Nitric) should be shunned to NOT remove the gold flake as a first step?
 
Tzoax said:
This is what i get - 0.5 grams of gold dust. I am amazed, I didn't expected that much. I had 0.5 grams of dust before aqua regia and then I removed 0.25 grams of white dust thru the filter, so how it is possible that I get 0.5 grams of gold + 0.25 grams of filtered dust from just 0.5 grams of material before aqua regia?
Click to expand...
I think you are correct, it's impossible to get that much gold from that dust. To me it doesn't look that pure. Have you washed it after precipitating the gold? Not only with water, but boiling in water, acid, ammonia... according to what Harold posted in the thread "Making gold shiny" (http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=325&p=2620#p2620).
If you haven't read it, do it! And do the washes and your gold will be a lot purer.

One of my first gold drops I made was from heavily contaminated gold chloride, I made a mess with mostly whitish crystals and a little gold sprinkled between the crystals. It turned out to be copper chloride crystals that was somehow precipitated by the huge amount of SMB I used in my first trials, just like you.

What surprises me is that you didn't get a large reaction from the stannous test after dropping the gold. When you add too much SMB it should give you a brown color that some people mistakes for gold and add even more SMB. Maybe it's because you used urea...
Tzoax said:
Then I added little urea at a time until urea stopped dissolving.
Click to expand...
I hope you meant stop fizzing, not dissolving. If you put huge amounts of urea into your gold chloride and then a lot of SMB at least I have no idea of what you would end up with.
I have never used urea myself, only read about it. I agree with Butcher when he said it can give you trouble.
You used so little nitric, adding it with a dropper, so you could easily have evaporated it. 4 grams (ml) of HCl and a few drops of nitric wouldn't take long.

Göran
 
Thank You Goran, I didn't washed it, I think You are right, I will do that and I will post results, I think that will solve the mystery. The urea wasn't fizzing at all, maybe I added (dissolved) more than needed and that made a mess. And yes, when I tested AuCl3 with stannous chloride after adding SMB, the result was deep black color just like You said. Thank You again for advices!
 
I boiled 3 times by 10 minutes in destilled water, then 3 times in HCl, then 3 times again in water. The loss was about 10 percents. Here is the picture.
( I was mixed together the dust from this topic - 0.5 grams, and the dust from my other topic "Refining Golden Foils From Fingers (Aqua Regia)" - 3.8 grams of dust and I process them together. At the end of cleaning process I ended with 3.8 grams, thats about 10 percents of loss).24.jpg
 
Very nice. That should be a nice button when you melt. Remove the heat and allow to cool fast when melted, if the button cracks and collapse on itself when it cools you made a nice pure button
 
joubjonn said:
Very nice. That should be a nice button when you melt. Remove the heat and allow to cool fast when melted, if the button cracks and collapse on itself when it cools you made a nice pure button
Click to expand...
Thank You Joubjon. I am planning to buy induction furnace for melting gold if I manage to collect some larger amount of powder.
 
I solved the mystery about remained white powder that survived aqua regia that we discussed earlier.
This is a result of precious metal analyze with x-ray fluorescence spectroscopy.white dust.jpg
 
You sure this is the white powder result? It seems to have every elements, Pt?

Regards
Kevin
 
kjavanb123 said:
You sure this is the white powder result? It seems to have every elements, Pt?

Regards
Kevin
Click to expand...
Yes, this is what remains from the mixed pins in aqua regia in the form of white powder.
 
Tzoax said:
kjavanb123 said:
You sure this is the white powder result? It seems to have every elements, Pt?

Regards
Kevin
Click to expand...
Yes, this is what remains from the mixed pins in aqua regia in the form of white powder.
Click to expand...
Just because the XRF showed an element at a low concentration doesn't mean there is any. XRF has a large error in the measurement, we have seen plenty of examples of that before here on GRF.

I only believe in the Sn Sb and In results.

Göran
 
Tin/antimony is a common solder. The powder is surely metastannic acid from the reaction of nitric on the tin. It is why most members remove the solder first, with HCl, before using nitric.
 
goldsilverpro said:
Tin/antimony is a common solder. The powder is surely metastannic acid from the reaction of nitric on the tin. It is why most members remove the solder first, with HCl, before using nitric.
Click to expand...

Thank You, I thought that because I mechanically removed solder ends there will be no tin present in larger amounts, now I know... I guess that when I boil with HCl I will need to neutralize HCl by incineration before processing nitric. Is there some other method for neutralizing HCl before using nitric? Could it be done by boiling in water several times or the incineration is the best method for that?
 
If the pins are made to hold tension (it has any part that is springy), the pin contains tin in its make-up. The base metal of the pin is phosphor bronze. Bronze is an alloy of copper+tin. You can remove all the solder from every part but if the pins are made to hold tension, it will still contain tin.
 
Geo said:
If the pins are made to hold tension (it has any part that is springy), the pin contains tin in its make-up. The base metal of the pin is phosphor bronze. Bronze is an alloy of copper+tin. You can remove all the solder from every part but if the pins are made to hold tension, it will still contain tin.
Click to expand...
Thank You Geo, can You tell me what is best method for processing mixed pins? I can't separate them by base metals because there is too much of pin types. Today I bought 10 server motherboards, 1 motherboard is about 1kg weight. I am planning to scrap all of the pins from them and process them together. Could You tell me what method is the best for that? (besides sulphuric, I dont have it, only nitric and HCl). Thank You.
 
Tzoax said:
goldsilverpro said:
Tin/antimony is a common solder. The powder is surely metastannic acid from the reaction of nitric on the tin. It is why most members remove the solder first, with HCl, before using nitric.
Click to expand...

Thank You, I thought that because I mechanically removed solder ends there will be no tin present in larger amounts, now I know... I guess that when I boil with HCl I will need to neutralize HCl by incineration before processing nitric. Is there some other method for neutralizing HCl before using nitric? Could it be done by boiling in water several times or the incineration is the best method for that?
Click to expand...

i would think that the true answer will be "incineration"

only takes a few minutes to incinerate & be 100% sure.
 
necromancer said:
Tzoax said:
goldsilverpro said:
Tin/antimony is a common solder. The powder is surely metastannic acid from the reaction of nitric on the tin. It is why most members remove the solder first, with HCl, before using nitric.
Click to expand...

Thank You, I thought that because I mechanically removed solder ends there will be no tin present in larger amounts, now I know... I guess that when I boil with HCl I will need to neutralize HCl by incineration before processing nitric. Is there some other method for neutralizing HCl before using nitric? Could it be done by boiling in water several times or the incineration is the best method for that?
Click to expand...

i would think that the true answer will be "incineration"

only takes a few minutes to incinerate & be 100% sure.
Click to expand...

Thank You very much Necromancer.
 

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