HCL-CL disolved gold solution is green.

[bob2064]

So here I was thinking that I was getting this gold refining thing down. Growing by leaps and bounds, and at a fast rate too. I have gotten (or so i thought) the AP method down. I can strip gold plating off real well. Lots of gold foils. I have been successful at getting foils 3 out of 3 times.

After two times of treating my gold foils in HCL-CL I have gotten a little precipitation of gold (brown flakes), with some silver chloride along with it. However when giving it hot ammonia bath my brown precipitation disappears, and the silver stays. There is usually more of the silver than there is brown precipitant, and it seems that the brown which i assumed was gold always seems to start to thin out and eventually disappear in the ammonia bath.

This time I have a lot more foils, and black dust than usual, and when dissolved in HCL-CL the solution turned green. I am assuming it is copper. My question is: If I Precipitate it with SMB will the gold precipitate, without the copper? Or is there another step i should take?

This is going to be my last run until get some more research in. Research I thought I didn't need, because of my "I'll figure it out" mentality....This mentality sometimes costs too much :|

 

[artart47]

Hi Bob!
When I recover any gold foils from fingers, sim cards or from any other source, I filter them out of the ap bucket along with any dark powder,
I then wash them out of the filter paper with a sprey-bottle into a large beaker.
I then add an equal volume of 32% hydrochloric acid, cover the beaker and they sit.
I do the same with the next batch and add them to the same beaker.
Agitate them everyday a couple of times.
if I harvest the gold from my bucket of small connector ends that are sitting in ap ( the flakes of gold come out of the plastic ends when I stir it.
They go in the beaker.
The beaker contains gold flakes and foils that are still contaminated with copper and sometimes nickel that remain on the back of the foils.
Also! if the foils are an alloy instead of pure gold, they need to have the remaining base metal removed.The contents of the beaker is not ready to disolve the gold yet.
When I deside I'm going to refine the gold, I put the beaker in a stainless steel stock pot with some water and bring it to a boil for about an hour.After it cools, if you look at it you see thet the acid is dark color. That is the base metals that were dissolved out of the foils. I decant the dark acid thru a filter paper and add distilled water, boil again.
Then add more acid and watch to see if it begins to darken. if it does, I boil it again.
I repeat this untill the acid doesen't darken
Now that all the base-metals are out of it, I refine w HCl/Cl.
If you want highquality gold,and want to avoid the kind of problems you are having, you never disolve the gold untill there is no bse metal.
artart47

 

[patnor1011]

Or, simply precipitate it with SMB (you can use SMB or cement on copper) from your dirty solution and wash resulted powder correctly. Then HCl/Cl or AR again. SMB again and then wash powder again. Only then melt.

 

[kurt]

Bob - what is the source you are recovering your foils from - I ask because if its from pins or fingers you should not have any silver in the mix so what you think is silver chloride may in fact be tin --- gold filled would be another story.

The other reason I ask is you say you are using hot ammonia washes - be very carefull with why, what & when you are using ammonia in refining - it can & will make explosive compounds along with acidic salts of metals.

It should "only" be used when washing the gold powders that you know contain traces of silver chloride from sources like karat gold or gold filled foils.

You real need to take that - "doing research" thing more to heart

ammonia & alcohol added to acidic metal salts/solutions can blow up in your face

Kurt

 

[bob2064]

Thanks for the information guys. It is much appreciated.
I learned something from art, that was good info to know.
And I will double refine this dirty solution.
The source is from RAM sticks, and some gold plated jewelery. Agreed on the more research thing...

Thanks again all of you for the info.

 

[kurt]

The source is from RAM sticks, and some gold plated jewelery.

Then as I mentioned I suspect what you thought was silver chloride is most likely stannic tin

The tin would have come from the plated jewelry (solder joints) &/or RAM sticks if they were whole sticks & not just the fingers trimed off the stick.

Have you read Hokes book yet?

Kurt

 

[bob2064]

But wouldn't the HCL baths dissolve the tin?

I rinse the foils in water, then HCL then water again before I dissolve them in HCL-CL.

I have another question regarding this dirty solution though.

I Finally found some tin to make my stannous chloride to test my solutions after SMB. Maybe I have been underestimating my gold yields.

I have calculated that a teaspoon of SMB is aprox. 5 grams (I could be wrong)
I put two teaspoons of SMB in my solution which from what i understand would drop about 10 grams of gold. This is what I estimated to get.
I tested my solution and it still had gold so i added more SMB another teaspoon, tested again and still came back positive.
so i poured in a little more SMB still positive, and a little more, with the same test results....

I am using food grade SMB so will I have to add more, than non food grade?
I just don't want to put too much SMB in the solution. This is my fist time using stannous chloride for testing, and guess i am not trusting the results because this is new to me.

 

[butcher]

These positive tests for gold are they a bright purple or are they brown to black?

Too much SMB can give a false brown some consider a positive test by mistake.

 

[bob2064]

Interesting.....The tests results in black.

I am inclined to think it might be too much SMB causing this result. I would say it starts off as brown, then turns black quite fast.

Thanks Butcher! Would you guess the same judging by a brown to black test result?

EDIT: Update. I just tested it again and looked closer at the result and the black does have a dark purple tint to it.

 

[artart47]

Hi again!
Wanna add a little thing I also do concearning tin. I don't know if it really nessesary or not.
I do alot of small batches of memory fingers in the ap and save the foils in the HCl jar as I mensioned earlier.
Some of the ram sticks display alot more visible gold plating. These ones have the gold fingers and they have little test circles between the fingers and the chips so I cut them close to the chips to also get the extra gold along with the fingers.
A posible problem is that there are also what looks like very small surface mounted devices ( capacitors/resistors...?) and they may have solder (lead/tin/silver) that could cause a problem when it goes to ap.
So, I give any of those, or anything I suspect may contain solder a boil in HCl with a few drops of sulfuric acid and a hot water wash before the go into the ap bucket with the rest of the foils. I believe it was Geo that taught me about the sulfuric back when I was a nooby!
Hpoe it helps!
artart47

 

[butcher]

Hmm,

Not sure if the test is positive, or if there may be colloidal gold in solution, or a false positive of too much SMB?

Try taking a small sample in a test tube, neutralize it with NaOH (sodium hydroxide), decant salt water with a pipette, rinse with hot water, decant again, incinerate the powder, add a few drops of HCl heat, decant rinse with hot water decant, then HCl/NaClO (bleach), heat to drive off chlorine and retest with stannous chloride.

 

[nōnāgintā trēs]

If it were me I wouldn't worry about it! However, if you really want to get rid of the copper or other contaminates in a situation like that, drop, dry, then add a little nitric and water. The copper will dissolve into it, the gold will not. I only wish I could clean my silver that way!!!

 

[patnor1011]

I would use distilled water.

 

[g_axelsson]

Don't forget to incinerate between dropping a chloride solution and washing with nitric acid. Any rests of the chloride will form aqua regia and dissolve some of your gold.

/Göran