removing gold from tungston crucible

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andycourson

Active member
Joined
Nov 19, 2008
Messages
25
Location
McGrann PA
I have a tungston crucible that cracked and cant be used any more. when it cracked some gold leaked out and is all over the side and a good coating inside as well. this crucible weighs a lot as there is a lot of tungston there. i dont want to set up a electro cell just to get this gold maby 3-4g. would hot hcl attack this? would ap be better? any ideas? would ap get under the gold and lift it off like gold fingers?
 

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andycourson said:
I have a tungston crucible that cracked and cant be used any more. when it cracked some gold leaked out and is all over the side and a good coating inside as well.
Click to expand...

Blink! Blink! :shock: :shock: :shock:

You're joking, right?

Harold
 
You should be able to remove the gold by attacking the Tungsten using hot HCl or concentrated peroxide.

Steve
 
I see this type of silliness all the time! People that want to melt precious metals in other metal containers, usually tungsten, molybdenum, or tantalum.


I even had someone send me a platinum crucible that they had tried to melt platinum in!!


As for your problem, trying to dissolve away the tungsten with hot HCl or with electrolysis in conc. NaOH will take forever and a year. KNO3 and KOH also work, when molten. It's a real bother...


If I had to use anything though, it would be 30% hydrogen peroxide--Steve gave good advice. A mixture of 50:50 HF/HNO3 attacks tungsten readily; plain HF does too, so long as the metal isn't in bulk (i.e. powder, turnings, thin sheet works best!).

Supposedly, there is another electrolytic route that uses ammonia and ammonium nitrate as the bath. US patent 4283258
 
the crucible gets used in a vac deposition machine. I wasnt using it to melt gold personally. after many uses sometimes the crucible cracks and this is the result. there is usually 50-60g melted in this and that is our gold sorce for e-beam deposition. this one cracked before I started working there. my boss gave me this when he found out my new interest in refining/reclaimation. he said when I get it off I have to buy lunch for the guys. seems like a fair trade.
 
Lou.

Would this be a good application for the vitreous carbon crucibles you had your eye on? Not for recovering this but in place of the tungsten?
 
Yes. At the temperatures employed they offer no contamination and minimum vapor pressure.
 
Has anyone done this yet? I'd like to know how fast it works. I have 35% H2O2. Would it dissolve Tungsten carbide? Do you just use straight H2O2?
 
I don't think it'll touch WC which is very inert.

As for how fast peroxide dissolves tungsten metal, well that depends on a host of factors, namely:

temperature
concentration
surface area
degree of solution agitation

I'd have to consult some literature to get a sure fire method for handling tungsten carbide.
 
I tried hot hcl with no luck, then hot hcl and 30% h2o2 this worked for a while disolving the thin coating of gold but without much affect to the thicker parts. the crucible started to dissolve and the outside became green. i got impatient with how long it was taking, and how i had to keep adding h2o2 to keep the reaction going. i then took out the crucible and started to break it in to pieces with vicegrips this worked very well because the tungston is brittle. so i got rid of everything that didnt have gold on it. i then used AR on it this seemed to leave the tungston alone and just disolve the gold. I wish i would have just put in AR to begin with. I ended up with 5 g of gold
 
Lou said:
I'd have to consult some literature to get a sure fire method for handling tungsten carbide.
Click to expand...

I didn't get the impression it was tungsten carbide, just tungsten.

Harold
 
Sorry for the confusion on this. My original question was regarding plain Tungsten, then as an afterthought I also wondered about tungsten carbide, and tungsten alloys in general.
 
@Harold, Noble Metals Recovery inquired about dealing with WC.


@andy, you did probably the smartest thing to do and what we all (I think) overlooked: increase the surface area!!

Aqua regia does attack tungsten, but it quickly makes a passivated coating and does no further damage.


Lou
 
that makes sense there was a definately a yellow/green coating on the crucible (actually at this point it is just a bunch of small pieces so it is really not a crucible anymore). When i took the pieces out of the AR the places where the gold was looked untouched, it was still shiny tungston. probably because i used very little nitric and it was all used up after the gold had dissolved.
 
Im going to get beat up for saying it but NH4I/I2/h202. The tungsten would be minimally attacked if at all, just the gold. The process is used in thin film circuit etching quite frequently. But if you dont have I2 already, it would be difficult to aquire.
 
Well, I goofed up...
I’ve got approximately an ounce of 30 micron gold mixed with similarly sized raw tungsten concentrate. The ratio of tungsten to gold appears to be approximately, 2:1.

I mistook and dumped a few bag of the raw tungsten in my rodmill while crushing some gold ore. Panning it is impossible, while the shaker table only seems to separate the finner gold from the rest, leaving the coarser fraction of gold caught up with the tungsten dust.

Any suggestions much appreciated.
 
bcgoldminer said:
Well, I goofed up...
I’ve got approximately an ounce of 30 micron gold mixed with similarly sized raw tungsten concentrate. The ratio of tungsten to gold appears to be approximately, 2:1.

I mistook and dumped a few bag of the raw tungsten in my rodmill while crushing some gold ore. Panning it is impossible, while the shaker table only seems to separate the finner gold from the rest, leaving the coarser fraction of gold caught up with the tungsten dust.

Any suggestions much appreciated.
Click to expand...
Wasn't the answer in this thread to deal with gold+ tungsten mix plain AR?
I mean you have powder from gold ore... So you can treat it with warm hcl to get rid of junk and base metal first. Edit: siphon/decant that (if its settled)
Then go straight for AR adding drops of nitric while heating solution until no reaction occurs.

Tungsten passivates... Gold dissolves.
As long as you dont let it cement out on tungsten (which i dont know if that would happen... I am just being extra cautios), and filter the AR solution after no more reaction occurs on heat + the nitric drops.
I am begginer so after that i would try adding fresh AR to insolubels after washing them and I would look for presence of gold with stannous chloride and see if I got all of it out of the concentrate.

Others can correct me if I am wrong or if I didnt thought of something important.
Just trying to answer you as I am begginer, so lets wait for mods to give their opinion.
 

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