Amount of 58% Nitric to dissolve 1g of Au

[bhilton]

Hi All, I was wondering if this math makes any sense.

If 1ML of common 68% Nitric acid dissolves roughly 1gram of gold.

Then does 1ML of 58% Nitric acid dissolve roughly 0.853 grams of gold?

I used a basic ratio calculation, 68 over 1 = 58 over x, therefore x = 58/68, or ~0.853.

I recovered gold from jeweler polish buffings, doing the first gold drop 2 nights ago. Then last night did the first refine and it took nearly 9 ml of my 58% nitric to dissolve all the gold mud.

Tonight after rinsing and hcl boiling, I will melt it and find out exactly what it is.

I'm very curious if the math will work - so in my theory, I used about 8.75ml of 58% nitric, so 8.75 * 0.853 = ~7.46g of Au.


Cheers everyone!

Thanks,
Bill

 

[Yggdrasil]

Hi All, I was wondering if this math makes any sense.

If 1ML of common 68% Nitric acid dissolves roughly 1gram of gold.

Then does 1ML of 58% Nitric acid dissolve roughly 0.853 grams of gold?

I used a basic ratio calculation, 68 over 1 = 58 over x, therefore x = 58/68, or ~0.853.

I recovered gold from jeweler polish buffings, doing the first gold drop 2 nights ago. Then last night did the first refine and it took nearly 9 ml of my 58% nitric to dissolve all the gold mud.

Tonight after rinsing and hcl boiling, I will melt it and find out exactly what it is.

I'm very curious if the math will work - so in my theory, I used about 8.75ml of 58% nitric, so 8.75 * 0.853 = ~7.46g of Au.


Cheers everyone!

Thanks,
Bill

1ml Nitric will dissolve anywhere from 2g to 0.5g.
It depends entirely on the conditions and what else is with the Gold.
Stochiometrically full strenght Nitric in AR will dissolve 1g of Gold.
Real world is that it takes what it takes.

 

[bhilton]

1ml Nitric will dissolve anywhere from 2g to 0.5g.
It depends entirely on the conditions and what else is with the Gold.
Stochiometrically full strenght Nitric in AR will dissolve 1g of Gold.
Real world is that it takes what it takes.

So you're saying if it took 8.75ml of my 58% nitric, I could yield over 1g of gold per ml? Now you've got me all excited!!

 

[anachronism]

So you're saying if it took 8.75ml of my 58% nitric, I could yield over 1g of gold per ml? Now you've got me all excited!!

If it was pure gold then possibly - but was it pure gold or gold mixed with other things?

 

[bhilton]

it would have been very close to pure, I did the dirty drop 2 nights ago, then last night I rinsed and hcl boiled and rinsed. Then re-dissolved the gold mud with 8.75~ ml. The mud was slightly darker brown but not really dark.

 

[anachronism]

You might be in for a decent result then. Here's hoping

 

[Martijn]

Hi All, I was wondering if this math makes any sense.

If 1ML of common 68% Nitric acid dissolves roughly 1gram of gold.

Then does 1ML of 58% Nitric acid dissolve roughly 0.853 grams of gold?

I used a basic ratio calculation, 68 over 1 = 58 over x, therefore x = 58/68, or ~0.853.

I recovered gold from jeweler polish buffings, doing the first gold drop 2 nights ago. Then last night did the first refine and it took nearly 9 ml of my 58% nitric to dissolve all the gold mud.

Tonight after rinsing and hcl boiling, I will melt it and find out exactly what it is.

I'm very curious if the math will work - so in my theory, I used about 8.75ml of 58% nitric, so 8.75 * 0.853 = ~7.46g of Au.


Cheers everyone!

Thanks,
Bill

The way you recover and process the recovered gold makes the most difference. Much more than a fixed ratio.
The first factor as said is the purity of the recovered gold.
Copper takes 3 to 4 times more nitric to dissolve than silver or gold. This is both in nitric alone as in AR, exept you don't dissolve silver in AR.
In AR you are not stoichiometrically using up the nitric on the gold as the gold ion binds to chlorine and not to nitrate. The released NO2 can be recaptured by condensing on the beaker wall after reacting as NO2 and bind to H2O and turn in HNO3.

So the question is: are you power digesting and pumping fumes through a scrubber or reusing it and maximizing nitric use (edited to change 'losses' in 'use'), it makes all the difference.

 

[bhilton]

You might be in for a decent result then. Here's hoping

Yeah!

It's from 227g (I purposely did exactly half a pound) from the bucket of jeweler polish buffing's material.

Before I started, I estimated 9-10g yield, based off a small sample I did for him a little while ago.

 

[bhilton]

The way you recover and process the recovered gold makes the most difference. Much more than a fixed ratio.
The first factor as said is the purity of the recovered gold.
Copper takes 3 to 4 times more nitric to dissolve than silver or gold. This is both in nitric alone as in AR, exept you don't dissolve silver in AR.
In AR you are not stoichiometrically using up the nitric on the gold as the gold ion binds to chlorine and not to nitrate. The released NO2 can be recaptured by condensing on the beaker wall after reacting as NO2 and bind to H2O and turn in HNO3.

So the question is: are you power digesting and pumping fumes through a scrubber or reusing it and maximizing nitric use (edited to change 'losses' in 'use'), it makes all the difference.

I'm only using a beaker with a watch glass completely covering it, all in my fume hood.

I would love to setup a scrubber some day.

 

[Yggdrasil]

I'm only using a beaker with a watch glass completely covering it, all in my fume hood.

I would love to setup a scrubber some day.

Then as Martijn said, if the beaker is tall enough (comparing to liquid level).
Much of the released NOx can be re-condensated and reused while it is in there, this will improve the mileage of the Nitric.
A proper condenser ill be even better but that is not for beaker.
If you just push on without such consideration, then most of the NOx will go up the chimney so to speak.

 

[bhilton]

Then as Martijn said, if the beaker is tall enough (comparing to liquid level).
Much of the released NOx can be re-condensated and reused while it is in there, this will improve the mileage of the Nitric.
A proper condenser ill be even better but that is not for beaker.
If you just push on without such consideration, then most of the NOx will go up the chimney so to speak.

Ok, cool. My AR dissolving solutions are always around or less than 1/5th of the beaker, so a 500ml beaker, I would be at 100ml solution or less.

 

[Martijn]

Ok, cool. My AR dissolving solutions are always around or less than 1/5th of the beaker, so a 500ml beaker, I would be at 100ml solution or less.

WIth slow addittions of nitric at 80 degrees C I stay below 1ml 68% per gram of gold with that method.
With 10% HCl by the way. Can't get any stronger anymore.