Dropping gold from used smb solution?

[Magua]

Hi all!

I want to thank every refiner here that has given information/techniques on precious metal refining. I have been reading and studying C.W. Ammens' book for several years and was happy to learn about and read Hokes book.

I ran my first batch of ram/pci fingers using AP. I washed the resulting foils in HCl 3 times (3rd lasting 24 hours). I dissolved in HCl/Cl. 24 hours later, I filtered and ended up with a nice golden clear auric chloride. I then added 5 g of Smb and stirred. The solution cleared and started forming a layer of light brown powder on the bottom. 24 hours later, the solution was clear but looked there was small suspended powder that was refusing to settle. I mixed some Smb with water and added to the solution; still didn't settle. The solution tested positive for gold (dark purple or black). I decided to just decant the solution into a empty distilled jug. I then washed and dried the resulting powder (per Lazersteves post) and melted into my first buttonish looking button.

Two weeks later and the used Smb solution is still testing positive as the first time, but there is no brown powder settling.

1. How can I get the gold out of the used Smb solution?

2. Why did some of the foils and powder float and refuse to sink? (In searching through several forums and posting, Harold_V, as well as others, make mention of incineration and washing before even starting the refining process). I neglected to perform this step and am wondering if this is my problems arose.

3. What temperature is the incineration done at? (Incineration to me implies temperatures of 1000 to 2500 F, which I thought would pyrolyze the pcbs and melt the gold prematurely?)

Thanks all.

 

[joubjonn]

incineration is most important when using nitric to dissolve base metals before the AR or HCl/Cl process to remove any leftover nitric.


I think you have a little misunderstanding of the processes, this was brought to my attention by another forum member.
You can proceed from the nitric acid process to dissolving the gold with aqua regia, without any problems.
incineration in this case is not needed between the processes, as you will have no need to drive off previous acid,or salts of that acid, it is when you have chlorides involved and are going to add an oxidizer like nitric that you would want to use incineration process to drive off chloride if your intent was to not dissolve gold in solution.

24 hours should be long enough to out gas the Cl. unless it was a really cold solution.

heat always works well when adding SMB.

Heat is not needed when using SMB actually it is the SO2 gas created that will help to precipitate the gold, heat can drive these gases out of solution where we need them in solution to help precipitate the gold.
edited by Butcher

 

[nickvc]

You could well be seeing a false positive test which results from using too much SMB.
Have you got a test solution made using a little gold dissolved to test your results against this solution?
This really helps and also ensures your stannous is still working.
If you use the search function top right of your screen and type in false positive it will show posts relating to this.

 

[g_axelsson]

Firstly, pyrolyzing is heating without oxygen, incinerating is heating with oxygen. Pyrolyzing leaves carbon and ashes while incinerating also burns the carbon and leaves only ashes from organic substances.

Secondly, I agree with nickvc, the stannous test looks brown to me which means there is excess of SO₂ in solution from overdosing the SMB. How much fingers did you start with? My guess is that you have precipitated all the gold from the scrap that were there.

Göran

 

[kurtak]

As others have said you may be seeing a false positive - however if you want to make sure there are no traces of gold left in your AuCL after precipitating with SMB put a piece of copper in your solution - that will cement out any trace values

I do this with all of my AuCL after precipitating just for the sake of insurance - its called the stock pot

Kurt

 

[nickvc]

Here I agree with Kurt all solutions which have had values in are put through my stockpot, better safe than sorry.

 

[Pantherlikher]

Yep. False positive it looks like but always being sure.

I have 3 different containers. First 1 has copper in it to drop anything that might still be in solution. When I need to put more solution into it, I move solution into second crock pot which has iron to drop copper. Before moving into iron pot, I move solution into 5 gal bucket and raise PH for iron and anything else still suspended.

This keeps my waste stream moving along to ward against elephants getting into the room. I periodically empty the conainers of solids. Recycling copper back into the first. It's very fine copper so it will dissolve quickly and drops anything above it into the pot.

The first pot before removing solids and seeing if any PMs made it in, I will put most of my spent AP solution into it for a couple days and it removes most of any copper still there. I was supprised the first time I did this as it removed all but very little solid material which I have yet to run through the system to see if there is any PM.

Notice the word "system" used in the last sentence...
My feeling is you should work to develope a system from start to finish before diving too deep into this field to help keep things simple and easily repeatible so nothing will be missed and keep the elephant at bay.

B.S.

 

[Magua]

incineration is most important when using nitric to dissolve base metals before the AR or HCl/Cl process to remove any leftover nitric.

24 hours should be long enough to out gas the Cl. unless it was a really cold solution.
heat always works well when adding SMB.

Thanks JoubJonn. Didn't know about heating when adding SMB. The temperature was around 15 - 25 F, was that to cold?

You could well be seeing a false positive test which results from using too much SMB.
Have you got a test solution made using a little gold dissolved to test your results against this solution?
This really helps and also ensures your stannous is still working.
If you use the search function top right of your screen and type in false positive it will show posts relating to this.

Thanks Nickvc. I don't have a test solution made yet, but I do still have a small amount of the original AuCl left over. I did a stannous test of that earlier today and it turned a dark purple (please see pic). I had searched about false positives before I posted my question and on all the posts I read, they said that the stannous would test a brownish color, but mine is a dark, dark purple or black.

Firstly, pyrolyzing is heating without oxygen, incinerating is heating with oxygen. Pyrolyzing leaves carbon and ashes while incinerating also burns the carbon and leaves only ashes from organic substances.

Secondly, I agree with nickvc, the stannous test looks brown to me which means there is excess of SO₂ in solution from overdosing the SMB. How much fingers did you start with? My guess is that you have precipitated all the gold from the scrap that were there.

Göran

Thanks Göran for clearing up my confusion about pyrolyzation and incineration. I started with 504 g (304 g of desktop/laptop RAM fingers and 200 g of PCI fingers) and ended up with a 1.2 g button. For some reason, the website flipped the order of my pictures and it looks confusing. When you said "the stannous test looks brown", are you referring to the coffee filter test? If so, that was a test of my AuCl before adding any smb. I accidentally used way to much stannous chloride and it turned the filter brown before I could put a drop of my AuCl on it. I put the drop in the very center where the discoloration is.

As others have said you may be seeing a false positive - however if you want to make sure there are no traces of gold left in your AuCL after precipitating with SMB put a piece of copper in your solution - that will cement out any trace values

I do this with all of my AuCL after precipitating just for the sake of insurance - its called the stock pot

Kurt

Thanks Kurtak. That is the same reason I was concerned about (not leaving any gold behind). After the majority of my brown powder settled, I could still see brown powder floating in the used smd solution. That was why I decanted and filtered it into an empty distilled water jug. (please see pic). Because there was so much powder in my filter and the used smb solution tested positive, I thought there might still be some in solution. What do you use for a stock pot? Is a plastic bucket okay?


Thanks all.

 

[bmgold2]

What do you use for a stock pot? Is a plastic bucket okay?

What do you use for a stock pot

As usual, Harold_V had some good advice on the USE of a stock pot.

Basically, YES a plastic bucket is fine but don't let the volume of wastes build up into The elephant in the room. I'll admit, I haven't read that whole thread yet but, what I have read looks like there will be some good information there.

I did notice there was at least one link in that thread that got a 404 NOT FOUND error when clicking on it. If you go to the address bar on your browser and change the phpBB2 to phpBB3 you will get to the post. Some links were not fixed when the board ?switched servers? or whatever happened. Just a tip to access some of the old threads.

 

[Pantherlikher]

Yep..
A plastice bucket's ok as long as it's thick like the 5gal. Don't use the filter at all after the drop. Everything liquid from then on goes into the stock pot. Just let the poured off solution sit for a couple few days and you will see solids settling. Or just go right into the stock pot for future refinning.

B.S.

 

[Magua]

Thanks Pantherlikher. I had read 4metals waste disposal post and I like your system equally as well, especially about the AP. I won't be using any more filters for the used smb, just straight to the stock pot.

 

[Magua]

Thanks bmgold2. I have been reading forums here since March 2011 as a guest and I am still amazed at all the posts that are here. I don't know how I've missed all three of those you recommended. Thanks for the links and info on searches.

 

[FrugalRefiner]

I have 3 different containers. First 1 has copper in it to drop anything that might still be in solution. When I need to put more solution into it, I move solution into second crock pot which has iron to drop copper. Before moving into iron pot, I move solution into 5 gal bucket and raise PH for iron and anything else still suspended.

This keeps my waste stream moving along to ward against elephants getting into the room. I periodically empty the conainers of solids. Recycling copper back into the first. It's very fine copper so it will dissolve quickly and drops anything above it into the pot.

Be aware that the iron will drop everything below it in the activity series, so if there is any cadmium, cobalt, nickel, tin, or lead in solution, iron will drop those along with the copper. Reuse in the stock pot probably won't cause problems, but it's something to keep in mind before using the copper in other ways.

Copper drops metals below it in the reactivity series (they're lower in reactivity), just as iron drops metals below it in the series.

Dave

 

[Anonymous]

24 hours should be long enough to out gas the Cl. unless it was a really cold solution.
heat always works well when adding SMB.

Actually I always find it works better cold. The gas stays in the solution longer.

 

[Pantherlikher]

Correct FrugalRefiner.
Anything that comes out of the stock pot for processing will need to be boiled a few times and processed as if it's a mess.

spaceships.
Warming the solution before dropping the gold. Not keeping the CL in solution. Keep the solution cool while it digests yes, but not for dropping.

B.S.

 

[moose7802]

24 hours should be long enough to out gas the Cl. unless it was a really cold solution.
heat always works well when adding SMB.

Actually I always find it works better cold. The gas stays in the solution longer.

I have to agree with John on this. I would cool my solutions before dropping rather than heating. Heat speeds up the molecules of the acids and makes them more active again so I would think it would want to hold more of your pm in solution if it's hot. Always test after dropping and if you have suspended gold on top that doesn't want to settle, just knock it down with the mist on a spray bottle.

Tyler

 

[Anonymous]

Panther if I put SMB in a warm solution then more of the gas bubbles out straight away rather than precipitating gold.

In a cold solution sometimes I hardly ever see bubbles although I can hear the process occurring. The gas hardly reaches the surface of the liquid but the gold drops out a treat.

(Post edited as I had put Dave's name in it incorrectly.)

 

[Pantherlikher]

O, ok, my bad.
Heat the solution to get rid of excess acids if any then cool to do the drop. That's what confused me from what ya'll said.

B.S.
... Sometimes a smack upside the head doesn't even help...