Gold doesn't precipitate?! Help!!

[brikka]

Hello all!

I have been trying to experiment the last few days with the gold ram, but I have had some negative outcomes. I don't quite understand why. I have done this experiment 2 times over with the same results, the first time thinking that I didn't neutralize the nitric acid, but I realized that might not be the problem after I have got the same results the second time around. The problem is the the gold does not precipitate - but I know it is present since I can see the flakes being dissolved.

Here is what I did. It's pretty much as stated in the instructions, except I did not cut the gold fingers. I have decided not to cut them because of the extra work, also I have seen there is a lot of gold circuitry in the ram as well.

Instead I have decided to put the whole ram chips in the beaker.

So I have then poured nitric acid over it, like in the instructions. This created a green copper solution, I have waited until the process is finished, then poured the green solution (because of copper) out, and discarded it. Since we are only interested in the gold.

After pouring out the metalic solution, I have added created a 1:3 agua regia mix to dissolve the remaing metals. Since the majority of them are gold, It's good enough for me. Soon all the gold flakes was disolved in the solution. I then poured the solution into another beaker, and since it's full of gold I decided to neutralize it with UREA and then precipitate it with SMB.

I have added a bit of water in the solution to dilute it, and started adding urea. I have added urea until the reaction was pretty much saturated, and the reaction was almost non existent.

After that, I added sodium metabisulfate to precipitate it. But for some reason it would just not precipitate, and i pretty much poured a bag of a pound of SMB in it, but it would just not precipitate. As you can see in the picture below it would just leave the saturated UREA and SMB.


I dont understand what was the problem, but here are a few things that MIGHT have affected the effects, though I really doubt it.

1. After the nitric acid, I did not wash the beaker with distilled water - though it should not have affected the results, since before it was just nitric acid.
2. I did not have sulphuric acid to precipitate lead - though I doubt this will affect anything.
3. Maybe something happened because we used the whole ram and not just the fingers... but then again - I REALLY doubt that would be the problem.

I just don't understand what would of went wrong. And I doubt the previous 3 points are the reason why this experiment did not work.

Please help! And thank you for your time,

Kind regards,

Tiberius

 

[mjgraham]

Seeing that this is your first post, welcome.
I guess I'll just post a few things even though what you have done is normally frowned upon, first sticking entire anythings in nitric, from your description I don't know if they still had the memory chips and you dissolved the tin and iron and all sorts of things, also if it was just copper and nitric it makes a blue solution. However stating that you had gold flakes after round one and put them in AR, I didn't see that after your tired the SMB that you tested with stannous chloride at any point before or after to see if anything happened.I guess my final questions is how many ram sticks? I have seem on average about 5-7 mg (0.005g) from a stick so your going to need a lot of them to see anything at all especially if your dropping it out of a lot of liquid. W/o any testing to see what you have in solution it is hard to say what is going on, on last thing sometimes the SMB takes time to work you might have to heat it some to drive off the excess gas. I am pretty new to a lot of this and some one else might have better ideas. I think removing stuff from RAM sticks with nitric is pretty tricky, if you had the fingers only and no other metals nitric would work good, for the most part acid peroxide(AP) works best for that type of material although much slower.

 

[brikka]

Thank you MJ - I have found out about this forum from a friend of mine. And after reading a bit, I can see this is a great community, and glad to be now part of.

I understand the negative frowning of just dumping the ram chips into the nitric acid, but I figured, I'm diluting everything BUT the gold, then I would just pour AR over the leftovers (pretty much 90%+ gold) and just get the gold concentrate. And just easily precipitate it! It obviously sounds simpler than it actually is.

1. It did create a blue solution. So I would assume it was mostly copper, from the ram fingers.
2. The gold flakes I talked about are mostly from the ram teeth.
3. I didnt try stannous chloride, should i test it before precipitation?
4. I put 200 grams worth of sticks - 11 sticks to be exact.
5. I didnt know exactly what happened.. i kept on adding SMB and it kept on having reactions... basically the bubbeling never stops. At first I thought it was because I didnt neutraize the solution and there was extra nitric acid that kept on dissolving the gold as it precipitated. That's why I did this process twice, but it didn't seem to be the problem? Could it be that the water that was from the tap is the problem? Or maybe the agua regia?

Thank you very much for your help.

 

[Claudie]

You won't be able to get the Gold out of the packages (chips) without crushing them first. With only 11 RAM sticks, you won't see much Gold, if you can see it at all. Follow the link in my signature line to the guided tour. Start there and do some reading and you will better understand the best processes to use and you will have a better idea of what yield to expect.

 

[mjgraham]

Well 11 sticks there is going to be at the most 50-70 mg (0.070g) and unless to me it is in a super small amount of liquid it may have just formed a verrry thing dust layer, i guess how much solution(HCl & nitric & H2O) that few amount of ram sticks may have only needed 2 drops of 68% nitric. Yes you should always test the solution, the color can tell you how much is in there, if it takes 5 min to barely make a purple spot you know there is not much there however if it instantly turns dark purple to where it is black looking you know what to expect. There is a lot of information on here, just takes time to read it and find it. What I did when I started I went to a forum section and started reading the oldest to newest when everyone was new. I have not done tons of ram sticks like a lot of people but your going to need a couple hundred to be happy. When I was new and didn't know a lot I was buying RAM, I processed 96 sticks once they had gold vias and of course fingers, I recovered 1.5g from that of course the experience was worth it I lost out money wise. Being careful is the most important thing there are a lot of ways to get hurt, plus it took me a bit but being patient is the main thing, it is not going anywhere.

 

[JHS]

Might i suggest that it would be much cheeper to read c.m.hoke,free on the forum,
than to buy gold and not be able to get it out of the acid.
I tried 6 months ago,stopped and started learning.I MIGHT BE READY TO TRY AGAIN IN ANOTHER
6 MONTHS.
GOOD LUCK
JOHN

 

[TomVader]

brikka,
It was probably just a misspelling, but did you use sodium metabisulfate or sodium metabisulfite? huge difference.

 

[brikka]

Thank you all for your replies:

Claudie - I don't intend to get the gold out of the packaged chips yet - I did this method because the mitric acid automatically disconnects the chips from the ram sticks - this way I can just collect them, then crush them or burn them afterwards. I only really want to recover the gold from the ram teeth as well as the small traces of gold from the circuitry. The rest I will process it later.

MJ - I dont think the problem is with the first method of nitric acid, since it does take away all of the copper, and other metals. After the first step of nitric acid, and after I empty out the non-gold metallic solution, I get in the beaker a bunch of gold flakes from the teeth, and I also the chips, and obviously the plasic slabs of the sticks - completely emptied of any other traces of any other metals, except gold. So before I add the agua regia solution 1:3 nitric:SMB , I know that the solution absorbs gold - especially since it becomes a golden liquid solution. After I pour the golden solution in another beaker, the signs of gold are completely gone. So I can assume that all the gold is present in the solution that I passed into the new beaker. Then, my question is, why is the solution not precipitating after following the simple > UREA > SMB steps??? The solution just becomes dark. I have attached some pictutures to show this, and also the SMB leftovers with no gold allow.

Tom - it wa sodium metabisulfite - sorry.

Thank you all

 

[butcher]

"I add the agua regia solution 1:3 nitric:SMB", "why is the solution not precipitating after following the simple > UREA > SMB steps??? "

The main problem is you think this is a simple process.

It is not that simple, Nitric is needed to oxidize the gold to get it to dissolve as a chloride in aqua regia, but to precipitate the gold we have to have the gold chloride free from the oxidizer.

Over-use of nitric acid, and still having free nitric acid or nitrates in solution, is most likely preventing your SMB from reducing your gold back into a brown metal powder, the oxidizer is oxidizing your gold (dissolving it back into solution), Urea is not a good way to deal with the common problem of over-use of nitric acid, Urea can cause its own forms of problems, urea can form dangerous compounds like urea nitrate, urea can cause complications when PGM's are involved, Urea does not really destroy nitric, it will destroy NO2 gas in solution (but if too much nitric was used it will not work that well), urea adds another contamination to your gold solution.

There are hundreds of posts and discussions, if not thousands or more of this exact problem you are describing now,written on the forum, A simple search and reading these posts will not only tell you how to get out of this problem, finding these in a search and reading several of them will help you get a better understanding of what to do and what not to do, and will help you also to understand how not to get into this problem in the first place.

Limit your nitric acid use to bare minimum needed to dissolve the gold.
Use the evaporation process to eliminate free nitric in solution (see Hoke's book).
Sulfamic acid can be used to destroy free nitric from aqua regia (forming the beneficial H2SO4 in solution).
Urea is a fertilizer, and works better to grow grass, can be dangerous, cause problems, and should not be used in aqua regia (my opinion).

 

[brikka]

Actually, this is what I found on the net.. this could possibly be THE reason why this is not working. I'm sorry I havent read Hoke, but I am sure he mentions this:

The chemistry behind AR is a bit more involved then you might expect, so we will just go over what is necessary for us to understand the process, in simple terms.
In Aqua Regia, the Nitrate ions serves as an oxidizer where the Chloride ions act as sort of "receptors" and accommodate the oxidized metals. Again, this is an over simplified explanation, but is enough for us to conclude that, excess of HCl in AR does absolutely no harm where an excess of nitric acid/nitrate salt will hinder any reduction attempts (i.e. Precipitation of Gold metal).

source: http://goldnscrap.com/index.php/scrap-cpu-a-chips/91-gold-recovery-process-from-ceramic-cpus-part-1

 

[brikka]

Butcher - thank you. I understood that this was the main reason that the reaction did not take place. I looked around for a similar answer but I didn't get a proper answer. It's just that most people claim that nitirc:hcl should be 1:3... which is not necesarly true.

Thanks Butcher, and thank you everyone else for the input. I will post with any new updates.

 

[srlaulis]

C.M. Hoke is a she, not a he. Read her book, Refining Precious Metal Wastes, before asking anymore questions. If your friend has been a member here on this forum for some time, he should have told you that already. Good luck and happy reading. You can find a download link here on the forum for her book.

 

[Claudie]

"So I can assume that all the gold is present in the solution that I passed into the new beaker."

It's always better to know, than to assume.
Get Stannous Chloride
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=41&t=5271&p=45030#p45030