White metal dental scrap

[Alliedft]

I came across a few pieces of dental scrap they were porcelain over what appeared to be silver metal. I assumed it would be silver content. I dissolved in nitric and as it began to resolve it was blood red. Once dissolved the solution was dark red/purple. When testing with stannous I get a purple that turns brown then green almost rainbow. I took a sample and add hcl and no silver at all. Anyone have any experience like this. I do not have dmg, but am ordering some tomorrow

 

[anachronism]

I think you've already worked out that it's more likely to be a PGM than silver. 8) 8)

Test it with your DMG and let us know the results but I think you're on the right path.

Jon

 

[Alliedft]

Platinum group metals won't disolve in nitric and havent heard of them being red when dissolving. These literally looked like they were bleeding when dissolving. I am actually thinking they are not noble metals maybe something alloyed with iron.

 

[Alliedft]

I know palladium will dissolve in hot nitric and is red, but I have never seen this much palladium in dental.scrap. I'm still.leaning to a non noble metal.

 

[anachronism]

I know palladium will dissolve in hot nitric and is red, but I have never seen this much palladium in dental.scrap. I'm still.leaning to a non noble metal.

Fair enough- that's why you're testing.

Not sure what your colour is but here's some I made this weekend.

 

[Lino1406]

Palladium. Lastly used for bridges. May contain a little gold

 

[Alliedft]

So would best course be to drop gold with smb then drop palladium with zinc. Or just drop all with zinc and start again when I have dmg

 

[Lino1406]

Sell it as is, so no need to re-melt palladium, which is hard

 

[Alliedft]

I understand that but right now they are all still in solution is it better to drop with SMB and recover the gold and then drop with zinc to recover the palladium or drop all with zinc and remove palladium from gold with nitric.

 

[Alliedft]

Top left is dental gold dissolved in ar this is after drop with smb and had clean stannous test allowed to settle overnight solution is clear but show PMS in solution

Top right is dental scrap dissolved in nitric, almost instant black from stannous goes orange to red to dark red almost black

Bottom is dissolved in AR and no drop yet dark orange almost brown

 

[Lino1406]

Palladium dental alloys contain very small amount of gold, negligible in my opinion and probably will cement together with palladium

 

[Alliedft]

So use zinc to drop and move on? I've never messed with palladium and wouldn't have done these without proper chemicals but I tested with nitric and they tested like silver and the dentist I got them from said they were junk silver and kobalt now he said they may be different since they were from the late 70s early 80s

 

[Lino1406]

If base metals are included, best to drop with copper foils

 

[Alliedft]

Once again I appreciate yalls help, got everything dropped solution is clear and a deep pile of black precipitant in the bottom. Thanks for saving a rookie again