Processing Dental gold with White gold

[Lobby]

I've been accumulating dental gold for a bit; probably have about 15 grams or so. I've been likewise saving the white gold I have, and was planning on processing them together.

Would you recommend for or against this?

On the one hand, there a possibility of some PGM's in the white gold pieces (ring prongs, etc), but on the other, the elements that give white gold its color (Ni, Zn, etc) might complicate PGM recovery.

As this is my first attempt at PGM refining, I thought I'd ask before turning on the torch.


:lol:

 

[nickvc]

Depending on the PGM content using inquartation could put them into solution with the silver or a good proportion of them which makes cementation and the use of the silver cell the route I'd follow.
Some of the PGMs could well stay with the gold so testing the AR solution would be advisable and again cementation would recover any values which could them be processed with the slimes from your cell.

 

[kurt]

I have never processed any dental scrap so I could be wrong here but as I understand it because of the mercury used in dental work don’t you first need to put the dental scrap through a retort process to safely remove/recover the mercury before doing any melting (inquartation) &/or before doing any chemical process?

Kurt

 

[Harold_V]

I have never processed any dental scrap so I could be wrong here but as I understand it because of the mercury used in dental work don’t you first need to put the dental scrap through a retort process to safely remove/recover the mercury before doing any melting (inquartation) &/or before doing any chemical process?

Kurt

That applies only to silver amalgam, but there's more to it than just looking for fillings. It has been common practice for dentists to cap teeth that are filled. In such a case, the crown will hide the presence of mercury, but it's easy enough to uncover. I used to smash the tooth with a small hammer, which will remove the crown, and separate the filling from both the crown and tooth. The filling will have a dull gray appearance, so it's easy to sort from the broken tooth and the crown.

If the crown shatters, it's not worth processing. I encountered several that were platinum group, but each is ductile enough to withstand breaking the tooth without shattering. If there is doubt, each one may need to be tested, which can be done by dissolving a sample with a little AR. The whole cleaned crown can be tested, which will speed up the test. If the solution is dark green, pretty good chance there's no value present, but it should be tested with stannous chloride. If the solution is a dark brown color, or leans green with brown highlights, pretty good chance there's value present.

Nick offered some excellent advice in regards to processing dental waste. By inquarting, the vast majority of the platinum metals will be sorted from the gold, and will be easily recovered at a later date from the slimes of a silver cell.

With dental work, if the white material leans blue/white, and is very brittle (can't be bent), it contains no values. Again, if there's doubt, do some testing, until you are very comfortable with your decisions.

Harold

 

[Lobby]

Thanks for the good posts, folks.

I'll treat this batch of gold differently from the standard scrap I've been processing. I'll certainly segregate the silver I'll recover from the dissolution of the inquarted gold to make sure I follow those PGM's.

Some of the dental I've recently received still contains the tooth material attached (I'll post pics later this week). I'll hammer those pieces off and look for the Hg containing amalgam. If there's any there, I'll make sure and break it off.

On the silver cell side of the issue: I've yet to start the cell up. I've been researching the site, trying to understand the electrochemistry well before I start anything. I've got about 30 oz of silver to process. Some of it undoubtedly has gold in it, as my early gold refining batches suffered from, uh, my poor technique. :lol:

Life is good. I appreciate everyone here for all the help I've been given.

 

[Lobby]

Oh, I've got standards (Au, Pt, and Pd) ready to be made, and will do so prior to actually starting the experiment.

Since so much of the white gold undoubtedly contains nickel, making sure I can test for it with DMG is important to me.

 

[Lobby]

Here's a few pics of what I'll be processing.

A strange alloy ring that the local refiner analyzed for me (XRF - 38% Au, 30% Pt, 18% Cu, 6% Ni, 5% Zn).

A palladium / silver tooth I had

The dental I had. Note the artificial tooth material... It came off pretty easily with a hammer. I couldn't see any mercury amalgam inside the gold caps.

It's not a bunch of gold, but enough for me to perform the experiment and continue my chemistry fun. :mrgreen:

The melting dish (although all of you know what this looks like)

Here's a pic of the melted buttons. The one on the left is the white gold I had. The other is the dental gold. I didn't melt them together, nor did I inquart them with silver, as I'll be doing some XRF testing this coming week and wanted to see what the instrument said.

It'll be a week or so before I continue the process, so ya'll don't wait up for me.

 

[nickvc]

Depending on the silver content of the material it may be possible to go straight to AR and dissolve everything but leave silver chloride to recover, traces of PGMs in this will again be recoverable through a silver cell. The gold may well need a second refining to achieve decent purity and the PGMs in the AR can be recovered by cementation.
If your looking for a great small silver cell Palladium posted pictures and details of his, that was awesome and very easy and cheap to make, even better easy to maintain and recover your slimes from. If your processing decent quantities of karat scrap and using inquartation your cemented silver will show the presence of PGMs by it's colour, it's takes a slightly darker colour, when this occurs or you believe it has PGMs in the mix a cell is the way to go, it makes refining them much easier.

 

[Lobby]

Thanks, Nick!

I'm tied up most of this week on biz, but will get the buttons analyzed (by an XRF manufacturer who's courting me). :lol: I'll post the results when I get them for your input. If the silver is low enough, perhaps a direct AR dissolution might be the path to take...

 

[Lobby]

I've been a bit busy (I refined a batch of "regular" scrap in the meantime), but finally completed the XRF analysis of the buttons. Interesting results:

XRF 1 and XRF 2 are machines I'm considering purchasing. "Refinery" is a Dallas based refinery with a local office; they graciously agreed to test the buttons.


My plan:

1. Make my gold, Pt, and Pd standards as per Hoke.

2. My SnCl2 is fine, but I'll need to make sure the DMG I've got works ok; I've only made a solution in alcohol. I'll see how that works with the DMG standard; if not well, I'll proceed with the lengthy dissolution in water.

3. Since the silver content in the Dental gold is so high, I'll proceed with a silver inquart / HNO3 dissolution.

4. I'll cement the solution with Cu, then collect the Ag in a bar. For fun, I'll see about XRF testing the silver to see if I can find any Pd/ Pt.

5. I'll dissolve the gold / Pt in AR, then drop Au with copperas.

6. I'll cement the post copperas solution with Cu, to see how much of anything I'll drop. Should be just a little Pt there.

If ya'll have any suggestions, I'm all ears.