Starting over, sorta.

[GotTheBug]

So in my first attempt a few weeks ago, had some fingers in ap, which went well, then after washes, went to hcl/bleach, which also went well. Then, the mistake, and my first, and hopefully last, experience on mixing batches. I had a small batch of pins, still in plastic, in hcl/bleach, not realizing then that I was dissolving much more than the gold from the pins.

Well, in my infinite intelligence, I filtered the mixture, assuming it was just AuCl into the first batch, and had an immediate whitish precipitate which was, in my estimation, copper, lead sulfate, or some other nuisance. Now I have an issue, obviously. A few grams of gold in a polluted solution.

I was thinking about evaporating down to solids, and starting with ap all over again, and proceeding from there.

Any chance of losing gold in the form of ions by evaporating?

Other thoughts?

Thanks guys, and feel free to call me names for this one, though it was my very first batch. lol.

 

[maynman1751]

I wouldn't think so as long as you evaporate below boiling temp. After completely drying, incinerate the powder to oxidize the unwanted materials, then re-dissolve. If I am wrong here, please someone chime in!

 

[Geo]

test the solution with stannous chloride. with a positive test (do not skip this, it ensures you have gold in case nothing drops) filter the solution of all solids and let it settle till the liquid is crystal clear. decant carefully as not to disturb any sediments. stop short of pouring out any sediments. you can get this little bit by putting it in a smaller container and let it settle again. add a small amount of SMB dry. not enough for what gold you have in solution, just a pinch and stir. did anything white form? did the solution become cloudy? if after a minute with no white precipitate, add enough SMB to precipitate all the gold in solution.

 

[GotTheBug]

test the solution with stannous chloride. with a positive test (do not skip this, it ensures you have gold in case nothing drops) filter the solution of all solids and let it settle till the liquid is crystal clear. decant carefully as not to disturb any sediments. stop short of pouring out any sediments. you can get this little bit by putting it in a smaller container and let it settle again. add a small amount of SMB dry. not enough for what gold you have in solution, just a pinch and stir. did anything white form? did the solution become cloudy? if after a minute with no white precipitate, add enough SMB to precipitate all the gold in solution.

Geo to the rescue once again!

Will do as advised, and have one question: If I do get a white precipitate after small amount of SMB added, what is it?

Paul.

 

[Geo]

it could be a sulfate of the metal contamination. i really dont expect there to be any but its better to catch it early. it usually happens with a saturated solution. i only advised it because i dont know what youve done so far. sulfides are soluble in water so if your solution is diluted it shouldnt precipitate out. the reason it occurs (im assuming because im no chemist) is when you add sulfuric acid to chloride salt of these metals a portion of the salt is converted to sulfides and sulfates depending on saturation and temperature. SMB is a precursor for sulfuric acid and substitutes for sulfuric acid in solution. if you get a precipitate with the SMB test, warm the solution below boiling and add a little concentrated sulfuric acid to precipitate all that will drop out.

WARNING: add sulfuric to solution slowly and in very small increments.

 

[g_axelsson]

Sulphides are generally not soluble in water but most sulphates are soluble.

Better watch the endings in the chemical names because they tell a lot about the compound.
Sulphides are composed with a sulphur atoms (S) at the end, for example FeS₂. Not soluble.
Sulphates are ionic compounds with sulphate ions (SO₄^2-) at the end, for example copper sulphate CuSO₄. Soluble in water.

I tried to find out what type of chemical bonds pyrite and other sulphides have. As far as I could tell it is an ionic bond with added contributions of metallic and covalent bonds. It's a really complex area. (ref: Chemical bonding in sulfides)

/Göran

 

[Geo]

thank you Goran. you are right. i didnt realize i listed them backwards until i read your reply. until i get used to typing out the same thing a couple of times i tend to mix up things, especially if its just two things. normally i check before i type but i was in a hurry. i apologize and will try to slow down and check things that may be crossed up.

 

[g_axelsson]

No need to apologize, we all makes mistakes and we all helps out to correct them.

8)

/Göran

 

[butcher]

“So in my first attempt a few weeks ago, had some fingers in ap, which went well, then after washes, went to HCl/bleach, which also went well. Then, the mistake, and my first, and hopefully last, experience on mixing batches. I had a small batch of pins, still in plastic, in HCl/bleach, not realizing then that I was dissolving much more than the gold from the pins.

Well, in my infinite intelligence, I filtered the mixture, assuming it was just AuCl into the first batch, and had an immediate whitish precipitate which was, in my estimation, copper, lead sulfate, or some other nuisance. Now I have an issue, obviously. A few grams of gold in a polluted solution.”

Where would the sulfate come from you do not mention adding sulfuric acid or sodium metabisulfite.

If your solution is just a chloride solution, the white precipitant could be silver chloride, lead chloride or just sodium chloride (table salt), it could also be copper chloride.

The copper chloride is soluble in HCl, the salt is soluble in water, the lead chloride is soluble in boiling hot water and insoluble in cold water, the silver chloride will not dissolve in cold or boiling hot water, this gives you a way to test for these metal salts, and also a way to separate them from each other.

”I was thinking about evaporating down to solids, and starting with ap all over again, and proceeding from there.

Any chance of losing gold in the form of ions by evaporating?

Other thoughts?”

You do not want to try to evaporate a solution of HCl and bleach, it would form copious amounts of salts, and you would loose the gold if you tried to incinerate this salt mixture with gold involved (your gold would go up in smoke).

Separate the salt from your solution and test it to see what it is and if it has values.

 

[maynman1751]

You do not want to try to evaporate a solution of HCl and bleach, it would form copious amounts of salts, and you would loose the gold if you tried to incinerate this salt mixture with gold involved (your gold would go up in smoke).

Separate the salt from your solution and test it to see what it is and if it has values.

Thank You Richard for correcting my screw up! I was unsure of my reply, hence the chime in part. Sometimes this stuff is very confusing. I didn't pick up on the gold being in solution. I guess that's how we learn.

 

[butcher]

What screw up? we are all learning. :lol:

 

[GotTheBug]

What screw up? we are all learning. :lol:

Lol Thank You butcher, and everyone else too. This is exactly why I covered the beakers and set them aside until I learned a bit more.
I have not added any sulfuric yet, just combined two batches together that I had prematurely assumed to be AuCl. The first batch was so clean and pretty, then the precipitate occurred when I added the second batch that had come from pins in plastic that had gone through pretty strong AP.

I have yet to continue the process, but will post results as soon as....

Thanks again guys for the fountain of knowledge!

I was going to share a pic later of my grandfather's old metal detector. He was a black sands prospector out in Arizona back in the 60's and 70's, and part of the reason for my interest, and profile name, is honor of his memory. I even have several of his old maps and mining claims.

Paul.

 

[butcher]

It would be fun to take the maps and that metal detector and walk a few steps in your grandfathers foot steps.

A picture of the ole metal detector would be nice.