# Diluting cell acids



## banjags (Apr 1, 2008)

I have just finished what looks to be a very lucrative cell run... my question is what ratio should I dilute the sulfuric acid to... Currently I have double the volume... Started with 2 litres now 4 litres. 

Now that it is diluted will the gold sludge settle to the bottom. It never completely settle out in the cell.


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## lazersteve (Apr 1, 2008)

Banjags,

It's best to pour off the bulk of the concentrate acid from the cell after it settles for a full 24 hours (all but about 1/2 cup in a three cup cell). Set this aside for your next cell run. Some of the gold powder will pour out with the concentrated acid and go into the next batch. The bulk of the black powder will remain in the bottom of the cell with the last of the concentrated acid. Dilute this acid and powder with 4-6 volumes of water. This is a change that GSP recommended and it helps stretch your acid out so you get more cell runs for the same acid.

If you have already started diluting the entire lot proceed to dilute to 4-6 times and let settle overnight or vacuum filter, next time you can use the modified routine.

Steve


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## banjags (Apr 2, 2008)

My dilute acid solution is not settling out... some has settled at the bottom, but the bulk remains floating at the very top. Flashing a light thru it even reveal some is kinda hanging in suspension in the middle area. Any ideas as to why it is not co operating?


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## lazersteve (Apr 2, 2008)

Banjags, 

Buffers may be causing the suspension. Run the lot thru a vacuum filter setup or thru 5-6 coffee filter to strip the black powder out.

Steve


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## banjags (Apr 2, 2008)

Just about finished filtering... The remaining solution appears to have a lot of copper in it. It is a light emrald green. I was expecting it to be clear. Any insight as to what that is? or is it just copper in the sulfuric?


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## Gotrek (Apr 2, 2008)

Copper sulfate probably no? Would make sense since copper/copper oxides and sulfuric form copper sulfate


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## banjags (Apr 3, 2008)

So after rinsing I went to dissolve in hcl and bleach and got a bunch of white fluffies. I not sure how this could be silver as the material this was deplated from what a whole lot of gold plated stereo connectors. Any ideas?
Edit - Now that the "fluff" is filtered out it is a light/medium grey in color.


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## SapunovDmitry (Apr 4, 2008)

Nope, i guess not silver. Most stereo connectors manufactured today are Ni/Au. I had to estimate gold content in some of these. It can be one of those (just naming possible components, saying nothing about solubility): Ni,Sb,Pb,Zn,P?,Cu.
From latsest things i can post the result of pin(Not audio connector (but i think materials are kind of same)) content made yesterday:
Typical fully plated (square 0,3x0,3 mm and 7 mm high) pin has by mass the following:
Cu 93%
Au 0,71%
Ni 2,5%
Zn 1,7%
Pb 1,8%
And some other minor spieces....


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## Anonymous (Apr 4, 2008)

Interesting SOLUTION you have! 

Have you forgotten that chunk of tin I gave you, make some stannous chloride and test your solution for gold.


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## banjags (Apr 4, 2008)

I know there is gold in there. I need to know what the white fluffies are... Now that the fluffies are filtered out they are a light grey sludge.


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## Gotrek (Apr 4, 2008)

banjags said:


> I know there is gold in there. I need to know what the white fluffies are... Now that the fluffies are filtered out they are a light grey sludge.



Maybe lookup the solubility of the metals above in Sulfuric. And see what color sulfate they produce.

If I remember from science class I think magensium become grey when sulfated(epsom).

Maybe one of your Leads used in your cell dissolved?


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## Anonymous (Apr 4, 2008)

banjags said:


> I know there is gold in there. I need to know what the white fluffies are... Now that the fluffies are filtered out they are a light grey sludge.


Banjags go for the gold and forget about the white fluff, add it to your stock pot.


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## lazersteve (Apr 4, 2008)

The gray sludge sounds like copper I chloride. Try to dissolve it with HCl. If you end up with a murky black solution it's copper I chloride.

Steve


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## banjags (Apr 4, 2008)

Ive got the gold out... It is a medium brownish powder. I am waiting for my melting dish to come in the mail and I will make a button. I was just wondering if the grey sludge was something of value. I expected a little more gold to come out than what did given how much stuff I deplated... about 50 lbs of a/v connectors.


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## Gotrek (Apr 7, 2008)

What's the weight of the precipitate?


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## banjags (Apr 8, 2008)

It is still sitting in a little bit of liquid I am waiting for my melting dish to arrive so I can melt it... I have no idea how much it could weigh. Couple grams maybe. We shall see.


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