Can tungsten that oxidizes trap gold?

[lanfear]

Hi guys,

I am now in the final processing of some ceramic cpu's with tungsten. Not all of the plates disattached from the cpu's so I will need to break them up further and run it again in AR.
My question is then as the title says. Can the tungsten trap gold when it oxidizes? Any experience?

Jon

 

[Barren Realms 007]

It would help to know what chips you are processing, chances are the ones you are talking about are a copper tungsten alloy so your answer would be yes. If you are using AR or poor mans AR with and adequate amount of HCL and a slight excess of nitric and agitate your solution is keeps this to a minimum.

 

[lanfear]

That is correct Barren. I will copy paste my question from another tread to give you some more info about my process so far.

Hi guys. I am in the middle of a process like this now. I have 2 PP and 2 cyrix with tungsten together with some normal pentium ceramics. I have spent 1 AR solution on them, tested the barren solution for gold and decanted barren solution to waste bucket.

What did you mean With Your last sentence? That I can minimize oxidation With agitation or that I can minimize gold getting trapt with agitation?

Jon

 

[Barren Realms 007]

That is correct Barren. I will copy paste my question from another tread to give you some more info about my process so far.

Hi guys. I am in the middle of a process like this now. I have 2 PP and 2 cyrix with tungsten together with some normal pentium ceramics. I have spent 1 AR solution on them, tested the barren solution for gold and decanted barren solution to waste bucket.

What did you mean With Your last sentence? That I can minimize oxidation With agitation or that I can minimize gold getting trapt with agitation?

Jon

The copper in the copper/tungsten alloy can cement out some of your values.

 

[lanfear]

Yes, that was my concern also. This is probably over simplyfied thinking, but I am also thinking that the oxidized tungsten atom will not cover the copper atom next to it. So the tungsten atom will oxidize and the copper atom will cement gold. Then the gold will go back into solution. This will continue untill only the oxidized tungsten is left. This is probably not the correct way of looking at it. 8)

Jon

 

[Barren Realms 007]

Yes, that was my concern also. This is probably over simplyfied thinking, but I am also thinking that the oxidized tungsten atom will not cover the copper atom next to it. So the tungsten atom will oxidize and the copper atom will cement gold. Then the gold will go back into solution. This will continue untill only the oxidized tungsten is left. This is probably not the correct way of looking at it. 8)

Jon

Sounds logical but it does not work that way in real life. :mrgreen:

 

[lanfear]

I know :lol: And also now that I have had time to think, the oxidized tungsten creates a bond with an oxygen atom, so now there is 2 atoms or maybe even 3 depending on the oxidation state.
But back to the solution. Agitation while the AR is reacting before the tungsten is oxidized? What will I accomplish with that? Do all the tungsten and copper go into solution?

 

[upcyclist]

If your solution is barren, could you decant your solids and just treat them with nitric to get rid of the copper, then AR to dissolve the Au, W, and WO₃?

 

[Barren Realms 007]

I know :lol: And also now that I have had time to think, the oxidized tungsten creates a bond with an oxygen atom, so now there is 2 atoms or maybe even 3 depending on the oxidation state.
But back to the solution. Agitation while the AR is reacting before the tungsten is oxidized? What will I accomplish with that? Do all the tungsten and copper go into solution?

That is the purpose of making sure you have enough HCl for your process, then when it is near the end of completion I have excess nitric in my solution and agitate it so that if any PM's are cemented onto the copper/tungsten heat sink they will dislodge from the heat sink and go back into solution. I always pour my solutions off of the processors with the solution hot then wash the processors off with hot water.

 

[lanfear]

If your solution is barren, could you decant your solids and just treat them with nitric to get rid of the copper, then AR to dissolve the Au, W, and WO3?

That depends on the copper & tungsten alloy. It will need to be 9kt like in inqauartation for the nitric to reach all the copper. And also AR will not dissolve WO3. NaOH will though.

That is the purpose of making sure you have enough HCl for your process, then when it is near the end of completion I have excess nitric in my solution and agitate it so that if any PM's are cemented onto the copper/tungsten heat sink they will dislodge from the heat sink and go back into solution. I always pour my solutions off of the processors with the solution hot then wash the processors off with hot water.

Ok. Thanks barren. I will try that on my second run of the processors bits that still have tungsten plates attached.

Jon

 

[Anonymous]

Don't over complicate this beyond what needs to be done. Have a good "hot" solution chemically and it really is no problem at all. As Frank rightly pointed out don't let the solution run out of either HCl or Nitric and you are good.

It really is no more complicated than that.

Good luck Jon.

Jon

 

[lanfear]

Thank you spaceships. I will post a Picture of the button tomorrow.

 

[Geo]

The tungsten caps will not trap gold to any extent that a hobbyist refiner could tell. By the end of the leach, you should have added a small excess of oxidizer to your solution. The important thing to remember is the brazing that holds the cap on is high gold content. If the process has run to completion, the tungsten cap should be released from the body and be a lime green color. Keep in mind that I'm a little color blind. It will be green though. The ceramic body should be smooth and without any rough spots where the legs were connected. These round dots should also be some shade of green and smooth to the touch. The tungsten cap should be loose from the base unless it's a P-PRO and then it will take quite some time longer than normal to get the cap to release.

 

[lanfear]

Thank you for that info Geo. I will need to leach the remaining processors then. The weather goth really cold so the filtering has to wait. The water started to freeze in the bottles when I was rinsing :x

 

[lanfear]

So I promised you a picture of the gold. Here it is. 4,8 g of 1 time refined gold.

 

[CalDreamer]

I posted yesterday in the help section before I saw this post. I am also having trouble with gold cementing to the cap. Knowing it is Tungsten/copper alloy helps me understand the problem. After I had attempted to process in aqua regia, I took the rinsed broken piece and boiled in HCL for about 6 hours. Did not really appear to do any thing. So I started to add nitric acid (until I ran out and then add Poor man's AR) until it seemed the reaction was done. Stannous test showed gold in solution. Filtered chips out of boiling hot solution and washed with room temperature distilled water. I do not know how much gold is in that solution. I set it aside because I could still see gold deposited to the tungsten/copper cap pieces.

I put a piece of a cemented chip in a test tube and left it in Poorman's nitric over night. The chip did finally separate and one piece has metallic gold on it and the other piece has a yellowish film. I've never used Poorman's AR and I was worried the Potassium was causing it to cement out.

Anyway, it sounds like from the posts above my missing step is agitation while in AR and rinse in hot water. Do you look for the cemented pieces and swirl/shake each in the hot solution until clean or just stir the whole batch? How long?

Thx

 

[Lino1406]

This may be of help: tungsten is attacked by H2O2

 

[Lou]

Tungstic acid traps many precious metals!!

 

[CalDreamer]

I placed a piece of the PentiumPro in H2O2 3% in a test tube (see photos) and it has been making a white pecipatate over the last two days. I am not sure if the white pecipatate is tungsten or not. I wasn't sure if 3% H2O2 would work but thought this process might go better if I could eliminate the tungsten first. It is very slow and would not be a method to remove the tungsten from the equation unless I waited a long time (then maybe). Maybe with a 35% H2O2 solution it would work quickly.

When I tested the clear solution in the test tube with Stannous Cloride, I received a spot that I thought was slightly purple but now I am not sure what the reaction is. It runs purplish but breaks up to a purplish gray and does not stain the plate.

Any thoughts are welcome.

Right now I am thinking I will put the processor pieces back in AR and when the reaction stops stir the pieces In the hot solution to remove the cemented gold. I will decant before I denox and I will further swish in any pieces in the AR that appear to have any cemented gold. I am not really happy with this process that is dependent on my visual inspection for cemented gold. No wonder PentiumPro recovery numbers are all very the board.

Before I ever process PentiumPro s again I will want to find a way to remove the tungsten lid first. Having it recent the gold is just to frustrating. Maybe I'll look into if Tungsten causes problems with Potassium Cyanide.

 

[anachronism]

Can I ask how you thought placing a pentium pro in an H2O2 solution would give you a positive stannous test?

Edit I would like to hear your chemistry thinking behind this assertation.