# Black Gold after drying ??



## Deezenuts (Apr 11, 2017)

I have been following a few tutorials on processing ceramic CPU's.

"Indeeditdoes" has a real nice video on the process on You Tube, and I have followed it exactly as he did. 

Part 1
https://www.youtube.com/watch?v=tQ_R8Gr26kk&list=PLgMkjzPpTqla6TqgZ6StacGSZ0C0u7Pvz&index=2

Part 2
https://www.youtube.com/watch?v=Hv4CcaTVJqY&list=PLgMkjzPpTqla6TqgZ6StacGSZ0C0u7Pvz&index=6

Everything was great (exactly like his video) until the drying process (which he didn't go into in the video)

I was using (2) 2000 Ml beakers, one for heating the acids and CPU's for oxidizing out the gold and base metals, and the other for filtering. I got all the gold into solution (tested with SC to be sure), and when it cooled, I poured from the first beaker into the 2nd beaker (with Ice), and used a few drops of sulfuric acid to leech the lead, and then filtered the solution to a new fresh beaker and added Urea to remove the Nitric acid (there was no reaction so I knew the acid was spent). I then added SMB and let the gold drop out overnight. The following day I did another SC test and there was no gold left in solution.

I could see the familiar black dust at the bottom. I then drained the majority of the solution, and then put the dust in a smaller 100 ML beaker for holding (with about 1/3 beaker of water to keep the gold suspended in the beaker).

After I had done a few runs, I collected the gold dust in the beaker, and then decided to fast dry the material, so I put the beaker on the warmer and let it dry out.

I was most surprised to find the dust never turned an orange color, but stayed black as Zinc powder even after completely dried.

Does anyone know why this would be? Is this normal? All the videos I have seen show the gold powder with a bright orange color after drying, but mine is still pitch black. I have not smelted it yet, but was hoping someone could help me to understand why the colorization. 

Did I do something wrong? (not sure what I could have done wrong, since the pristine solution had the gold drop with SMB, and the dust looked just like the videos I watched until I let it dry over heat.

any help would be appreciated.

Thanks in Advance.


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## kernels (Apr 11, 2017)

How much gold were you expecting and how much SMB did you use ? I believe overuse of SMB can drag some base-metal down with the gold. I would characterize the color of dried gold powder to be between dark brown and light brown depending on purity. 

Either way it is probably not a serious problem, you can always do a second refine on the powder.

edit - you haven't mentioned it, but gold powder that has been dropped from solution usually goes through a washing process of water and HCl before drying too.


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## Deezenuts (Apr 11, 2017)

Thanks for the quick reply.

to clarify, Yes, I did several water washes, and an HCL wash as well. I should have stated that.

I was expecting about 4-5 grams total (estimation from the CPU's, assuming about .1 grams per CPU to be conservative). I used about 3 tablespoons of SMB to drop the gold. 

I ended up with closer to 8 grams, which I thought was odd, unless the CPU's had a lot more gold in them than I calculated for.

In regards to purity of the gold: wouldn't gold being dropped through SMB be like almost pure? I get the purity before oxidation can be all over the board based on the quality of gold used, but I thought that dissolving in acid and dropping with SMB would be almost pure?

I did think about running a second refining, but I really wanted to see if I was making a mistake before doing it all over again, and possibly making the same mistake again.

I did not realize if i used too much SMB I would leech out other metals with it, good to know.

thanks.


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## kernels (Apr 11, 2017)

Yes, I think 3 tablespoons of SMB would have been overdoing it. I believe you want 2g of SMB for every 1g of gold. I'm sure someone more experienced will chime in on whether that is the correct ratio.

Gold dropped with SMB should be pure, but as I said, if copper gets dragged down with the gold, then it will be a bit less pure.


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## g_axelsson (Apr 12, 2017)

Usually the amount of SMB to use is a gram per gram of gold, though it seldom is a problem if you add extra.

I end up with black gold if I drop from a dirty solution or from a very diluted solution. It is usually very fine and has a hard time to sediment on the bottom, is easily disturbed and just a pain to work with.
In those cases I usually decant most of the liquid, add some HCL and a bit nitric to redissolve it. Now you have a lot less solution to work with and a second drop is usually brown or yellow. In the end it saves me time as it seldom takes more than 15 minutes to do a second drop.

For 8 grams it would take about 30 ml of hydrochloric acid and less than 8 ml of nitric. Add in portions. to not overdo it and the powder can react violently if you add it all at once.

Some people have the gold change from black to yellow when boiling for a while in HCL, but I haven't tested that yet.

Göran


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## anachronism (Apr 12, 2017)

There are a lot of myths about SMB. The true answer is that in reality it takes whatever SMB is required because there are other factors to take into account. For one, excess Nitric, and for another the presence of some base metals which can interfere with the precipitation process in the short term. Using too much SMB really doesn't cause any issues beyond small drag downs of copper which can be easily cleaned up in the wash process. As such, overall it's not practicable to try and work this stoichiometrically. 

Also remember that it's cheap so there's no need to worry about using a bit too much.

If your gold looks black then as has been mentioned you need to clean it but there's no way you'll have 3g of copper in 8g of dropped gold. It sounds more like your yield is better than you thought- which is a win!

Jon


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## Deezenuts (Apr 15, 2017)

Thanks for the support and help.

I think Göran hit the nail on the head when he said:


g_axelsson said:


> ...I end up with black gold if I drop from a dirty solution or from a very diluted solution. It is usually very fine and has a hard time to sediment on the bottom, is easily disturbed and just a pain to work with.
> Göran


That was exactly my same experience, dirty solution seems to have allowed extra material to come out with the SMB. It was very fine and hard to work with, easily disturbed. 

I ran a second refinement today, and it was text book. The gold was heavy, and fell straight away to the bottom of the beaker, no issues with sedimentation. Color was a medium yellow to rust color. I was quite pleased  



g_axelsson said:


> For 8 grams it would take about 30 ml of hydrochloric acid and less than 8 ml of nitric. Add in portions. to not overdo it and the powder can react violently if you add it all at once.
> Göran


Your measurements were perfect, I added HCL, and added low heat, a few minutes in added 2 ML at a time over 20 mins maybe, and it was a breeze.

So, after the second run I ended up with just under 7g of gold. It would appear this batch of CPU's has a little more gold than I anticipated....yummy :G 

Thanks again!!


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## g_axelsson (Apr 15, 2017)

Great! Always nice when we err on the lower side.  

What I think is happening when dropping gold from a dirty solution is that some of the other metals in solution attach to the surface of the gold and stops it aggregating into larger particles. When a particle have a coating of other metals the gold stops to add to it. The only way to clean up that surface is to boil it in HCl (maybe sulfuric acid also works, haven't tried it) or redissolve the gold again. Without a lot of contamination on the surface the gold particles can stick together into larger pieces and we get that yellow gold powder we want.

The reason the gold is black isn't that it is covered by something that is black, but the gold particles are so small that the wavelength of light is comparable in size of the particles. They simply absorbs light at that size. As a comparison, look at colloidal gold that have different colors depending on the size of the particle.

Göran


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## goldenfrog (Apr 27, 2017)

I feel that I have read Hokes and the literal plethora of Excellent information and videos and listened to the comments of the Refining Gurus we have on this site. So for my first post, I wish to pose the question that everyone seems to dodge. 
What exactly causes the gold to fall out in that ultra-fine black powder? 
I have re-dissolved this same black powder several times, each time using clean beakers, concentrated acids, filtering over and over, and using sulfuric to drop any lead out. filtered, re-filtered, de-Nox'd, and dropped with SMB. My AR gold solution looks brilliant yellow (unlike the above video... that looked pretty filthy), as soon as I add the SMB, my solution turns clear then darkens, darker and darker until it starts to drop that graphite fine black powder again.
I have seen the question posted: "should I melt this powder?" and never really saw an answer on that. 
The only reason I have not tried to melt it is the simple fact that I should have around 6 grams of gold and the powder is only a very small fraction of that volume. My next plan is to try to boil the powder in HCL then using HCL and bleach to dissolve the powder, and drop with SMB but my hopes are dwindling that I will ever see that pretty brown powder. 
So far it seems SMB is the preferred method to precipitate, at least the cleanest... 
I am at a loss


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## FrugalRefiner (Apr 27, 2017)

goldenfrog said:


> I feel that I have read Hokes and the literal plethora of Excellent information and videos and listened to the comments of the Refining Gurus we have on this site. So for my first post, I wish to pose the question that everyone seems to dodge.
> What exactly causes the gold to fall out in that ultra-fine black powder?


Assuming you mean "why an ultra-fine black powder", instead of a "nice, clumpy, cinnamon brown powder", the two main factors are dirty solutions and dilute solutions. Both will cause the precipitate to be more finely divided, giving it a black appearance. The smaller the individual particles of precipitate, the darker it will look. In dirty solutions, there are other ions in solution that "get in the way" of the gold particles bumping into each other and growing larger. In dilute solutions, the particles are just too far apart to agglomerate any further.



> My AR gold solution looks brilliant yellow (unlike the above video... that looked pretty filthy), as soon as I ad the SMB, my solution turns clear then darkens, darker and darker until it starts to drop that graphite fine black powder again.


A brilliant yellow solution usually means that it's not dirty, but it may also mean it's fairly dilute. A concentrated solution, made by using just enough acid to dissolve the clean gold, will be a beautiful orange color.



> I have seen the question posted: "should I melt this powder?" and never really saw an answer on that.


If you're done refining it, melt it. If you plan to rerefine, leave it as a powder because it will dissolve much easier.



> The only reason I have not tried to melt it is the simple fact that I should have around 6 grams of gold and the powder is only a very small fraction of that volume. My next plan is to try to boil the powder in HCL then using HCL and bleach to dissolve the powder, and drop with SMB but my hopes are dwindling that I will ever see that pretty brown powder.


I'm not sure I understand the logic. If the powder is only a fraction of what you expected, it is what it is. It won't grow whether you melt it or not. If you think you've left some gold behind, look back to your undissolved material and the solutions you've used up to this point. If you're afraid you're going to lose weight through further washes because it's not yet pure, again, it is what it is. You'll either get a larger button of impure gold, or a smaller button of purer gold.

Having said that, there are frictions with every step, i.e., you temporarily misplace tiny amounts along the way. If you're careful, you'll eventually capture those misplaced bits.

Dave


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## kernels (Apr 27, 2017)

What makes you think that you should have 6g of powder ? What was the starting material and process ?


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## goldenfrog (Apr 28, 2017)

I agree, I have probably lost a bit each time, I started with about 3 lbs of memory sticks as well as a few other boards and cpus from when I first started and didn't realize they all needed different techniques.
I admit I don't take the measurements as well/often as I should so any inconsistencies with my expectations are my own fault. 
My Stock pot should yield quite a bit from all of my attempts :roll:


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## FrugalRefiner (Apr 28, 2017)

goldenfrog said:


> I agree, I have probably lost a bit each time
> My Stock pot should yield quite a bit from all of my attempts :roll:


Not lost, just misplaced.

Dave


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