Dissolving Base Metals After Inquartation

[chemist]

This is my first post and I'll try not too seem too thick. I have read Hoke and many posts on this board. I learned a LOT from this board. So, here is my problem:

Buying nitric acid has been impossible where live. The scientific supply houses will only sell to "businesses" and I can't locate any source of KNO3 or NaNO3.
So, I have inquarted a small (2 Troy oz) batch with brass (copper and zinc). I used brass because I have a lot of it sitting around. I am sure that the metal is now below 25% gold and the silver is below 5%.
I would prefer to use nitric to dissolve away everything but the gold, but, like I said, I don't have any nitric acid.
I do have sulfuric (auto parts store) and HCl (hardware store). I did small test samples and neither had much of an effect on the metal.
I would prefer NOT to make Aqua Regia because this would is a more complex process.
How should I proceed? Should I heat the H2SO4? Heat the HCl? Any ideas or suggestions would be appreciated.

 

[jimdoc]

I think using brass was a mistake. It may contain tin and give you problems. The experts will let you know for sure. Look up poormans nitric in the forum search to see how to make nitric when you can't buy it.
Jim

 

[qst42know]

Both nitrates are available on eBay to make poormans AR.

The risk of using brass are the small additions of lead in the alloy which make it more machinable. You should add a small amount of sulfuric after all your metals are in solution to drop the lead as sulfate and filter your solution to clarity.

 

[butcher]

brass mostly Cu/Zn
bronze mostly Cu/Sn

 

[chemist]

I agree that using brass was a mistake, but it was handy. It is copper and zinc. There may be some small amount of lead, but that doesn't bother me now. What's done is done. Next time I can use silver.
I didn't really want to use poor man's AR because it seems a lot more difficult and dangerous than using a single acid like HCl or H2SO4.
I suppose that I could buy the nitrate on eBay and then dissolve it in sulfuric to make a low concentration of nitric that would dissolve the copper and zinc. Do you think that this would work?

 

[qst42know]

And yes brass can contain some tin.

Here is a list down aways of some common alloys, but there are many others depending on the desired properties.

http://en.wikipedia.org/wiki/Brass

 

[Platdigger]

It's a fair bit dangerous, but you could boil it in the sulfuric until concentrated, and then continue boiling until nothing is left but the gold.

 

[qst42know]

I agree that using brass was a mistake, but it was handy. It is copper and zinc. There may be some small amount of lead, but that doesn't bother me now. What's done is done. Next time I can use silver.
I didn't really want to use poor man's AR because it seems a lot more difficult and dangerous than using a single acid like HCl or H2SO4.
I suppose that I could buy the nitrate on eBay and then dissolve it in sulfuric to make a low concentration of nitric that would dissolve the copper and zinc. Do you think that this would work?

The recipe and procedure for making poormans nitric is in here:

http://www.scribd.com/doc/18470741/Gold-Refining-Forum-Hanbook-Vol-1

Poormans nitric works well on base metals but has caused me problems with silver, which will go away once I'm set up to distill it.

 

[glorycloud]

The recipe I was given for making nitric acid is one cup of sodium nitrate dissolved in water
for an hour then you add one quart of H2SO4 and let it sit overnight. Pour off the clear liquid
leaving behind any undissolved sodium nitrate.

It seems to work for me. Seriously - be very, very, very cautious using this stuff
as it is very, very, very not good to breath the vapors. Search BFRC or "red cloud
of death" on the forum - PLEASE!!!! :shock:

 

[chemist]

I did an experiment with a mixture of HCl and hydrogen peroxide. It definitely dissolved something.
Is there any possibility that this mixture dissolved gold?

 

[Palladium]

I did an experiment with a mixture of HCl and hydrogen peroxide. It definitely dissolved something.
Is there any possibility that this mixture dissolved gold?

Yes ! If you add to much h2o2 to fast.

 

[markqf1]

Test, Test, Test.
Sncl2 is your friend.

You should have enough cu involved to precipitate the gold back out as a fine black powder.
So fine in fact, It will be hard for you to filter it.
Best to let it settle and siphon off the liquid, then test again.
As Oz says, ... just my two cents worth.
Hoke?

Mark