How to melt palladium

[Ultrax]

To be honest, I didn't test how brittle it is, but the powder melted into a drop successfully. But I think you're right , an oxidizing atmosphere is needed. For one single melt, a temporary thin magnesite coating can be made inside a graphite crucible.

 

[orvi]

Of course it may be useful, I merely pointed to this fact so you did not expect an answer from him.
Have you actually tried this?
I thought Pd was like Pt and did get brittle and contaminated by Carbon?
Maybe I'm be wrong though

I do not know about platinum, but Pd and definitely Rh form "alloys" with carbon. Palladium melted in graphite is dark in colour. Few times, our PGM alloys melted in graphite crucibles sticked to the walls and they needed to be chisled out - so yeah, carbides are real All in all, without vacuum furnance you will likely obtain metal foam.
I had good experience with melting in quartz dish in induction furnance. Foam as expected, but allright for selling. As long you do not "switch" to the reducing enviroment (eg touch/stir with graphite rod, blow oxy/fuel flame over or pour it into the graphite mold), you will obtain relatively nice - altough foamy - button. It also tend to spit when you do this

 

[Yggdrasil]

I do not know about platinum, but Pd and definitely Rh form "alloys" with carbon. Palladium melted in graphite is dark in colour. Few times, our PGM alloys melted in graphite crucibles sticked to the walls and they needed to be chisled out - so yeah, carbides are real All in all, without vacuum furnance you will likely obtain metal foam.
I had good experience with melting in quartz dish in induction furnance. Foam as expected, but allright for selling. As long you do not "switch" to the reducing enviroment (eg touch/stir with graphite rod, blow oxy/fuel flame over or pour it into the graphite mold), you will obtain relatively nice - altough foamy - button. It also tend to spit when you do this

If you have an inert atmosphere there will be no foaming I believe.
For instance, Argon covered melt.

 

[Yggdrasil]

I do not know about platinum, but Pd and definitely Rh form "alloys" with carbon. Palladium melted in graphite is dark in colour. Few times, our PGM alloys melted in graphite crucibles sticked to the walls and they needed to be chisled out - so yeah, carbides are real All in all, without vacuum furnance you will likely obtain metal foam.
I had good experience with melting in quartz dish in induction furnance. Foam as expected, but allright for selling. As long you do not "switch" to the reducing enviroment (eg touch/stir with graphite rod, blow oxy/fuel flame over or pour it into the graphite mold), you will obtain relatively nice - altough foamy - button. It also tend to spit when you do this

In jewelry, Pt has to be soldered with a strongly oxidizing flame to avoid brittleness.
Preferably Hydrogen flame.

 

[orvi]

If you have an inert atmosphere there will be no foaming I believe.
For instance, Argon covered melt.

I believe that it would be significantly lower than that of oxygen or hydrogen - due to relatively obvious reasons. But it will definitely has some solubility. Never tried this, as I do not have proper equipment in hand.

 

[Yggdrasil]

I believe that it would be significantly lower than that of oxygen or hydrogen - due to relatively obvious reasons. But it will definitely has some solubility. Never tried this, as I do not have proper equipment in hand.

If I'm not mistaken. The foaming and spitting of both Silver and Pd comes from its affinity for Oxygen.
So if you deprive it from Oxygen it should behave.

 

[orvi]

If I'm not mistaken. The foaming and spitting of both Silver and Pd comes from its affinity for Oxygen.
So if you deprive it from Oxygen it should behave.

Yeah, it can be rationalized like that. It tend to adsorb oxygen, because it can bind it temporarily in the melt, easy saying. Strange and fascinating metals

 

[samuelbaldwin010]

I know this is an old thread and all but I was hoping someone could give me some advice.

I have been trying to melt some palladium sponge into a metal button without having very good results.
I am using an oxy/acetylene torch.

Yes, I am aware that it tends to bubble up due to the oxygen absorption and what have you, however I have also heard conflicting information about whether or not it can be done and get an acceptable metal button from it.

On a sreetips video, he uses a oxy/acetylene torch and it comes out looking like a good button. And he even uses some borax for melting it too, which I have also heard was a no-no.

My attempts at melting have resulted in one time it looked like a bluish gray lump of melted borax and you could see all the tiny air bubbles in it but also it had some very small beads of silvery melted palladium through out it, it should be noted however, that on this occasion I used a Mapp pro/oxygen set up instead of the oxy/acetylene torch I have used this time.

On this particular occasion I used the oxy /acetylene torch set up and I had used a melt dish that I had some borax already glazing on it, but when I tried melting the palladium sponge , whatever didn't blow Away (and alot did!), ended up melting into a gross looking blackish-brown cluster f@#$!

So I am hoping for some of the wisdom of our fellow members here to help point me in the right direction and hopefully help me fix what I have already screwed up. I have a pretty good amount of both platinum sponge and palladium sponge from leaching cats and I would like to get some buttons out of the deal for my efforts.

Thanks in advance.

-Samuel

 

[samuelbaldwin010]

No one care to touch on this?

 

[goldandsilver123]

Palladium metal reduced with formic acid and a base (NaOH or NH4OH) ~99.9%, is vacuum filtered, dried in air (over night).

I melt this material with LPG/O2 torch WITHOUT borax, new crucible.

I does oxidize a little bit and bubbles, the palladium button have a purple hue, but it does roll well.
I do not have hydrogen for the torch and still haven't bought a induction heater, the VEVOR one that ORVI suggested doesn't ship to my country.

 

[lazersteve]

No one care to touch on this?

1) no Borax. Use a bare silica dish, no glazing.
2) xrf the Pd powder/sponge for an idea of the purity. If its below 99; refine it again.
3) Compress the sponge/powder into a tight mass. You should be able to pick up the compressed pellet and it not fall apart.
4) adjust your oxy/propane torch so the flame is slightly orange with just enough O2 to prevent carbon from appearing on the edges of the white dish.
5) as the pellet is sinstered and starts to shrink slowly add more O2 with either the push lever on your cutting torch or the O2 dial if you don't have the lever on your rig.
6) only add enough O2 to affect a liquid melt, not more than required as additional O2 has a cooling effect on the button. You will be able to see the point where the metal begins to melt.
7) fuse the mass being certain you can push it around with the flame adjusted correctly.
8) slowly dial back the O2 and pull the torch away from the molten smooth surfaced button.
9) if you get a dull gray or peacock colored surface finish either play the torch on its surface with minimal O2 or pickle the button in dilute HCl.

The attached photo shot 99.99 to xrf as a light gray powder and after the melt using this process. I used an oxy/propane rig with the cutting O2 assist lever on the torch handle. No pickling or HCl treatment was required. Note the crystalline structure on the button.

Steve

 

[lazersteve]

I have 7kw induction on site and prefer the torch melted finish of torch melted Pd. Lower than four nines Pd typically produces a smooth silvery surface.

Steve

 

[dvontedlores]

I have 7kw induction on site and prefer the torch melted finish of torch melted Pd. Lower than four nines Pd typically produces a smooth silvery surface.

Steve

What kind of crucible do you use with your induction heater for palladium? And what form of palladium are you using? I cannot seem to find a crucible with a graphite susceptor on the outside and a fuzed quartz crucible on the inside. I am trying to melt palladium in a argon atmosphere vacuum chamber but I have been unable to melt a small 1g square I bought to test it with.

 

[eaglekeeper]

1) no Borax. Use a bare silica dish, no glazing.

Will the button release easily from the unglazed dish.

Awesome button by the way.

 

[lazersteve]

Here's a short video of my 3.5kw unit melting ~2g of 99.9% fine Pd BBs into a single button. The video was filmed in real-time with no time lapse.



In the video I simply used a graphite crucible with no other lining. I do have larger crucible and linings, but they draw more amps than the 3.5kw unit will handle. I have not tried to melt larger amounts as I prefer the finish I get with torch melts for Pd.

Steve

 

[lazersteve]

Eagle,

The button breaks free on its on if allowed to slowly cool in the unglazed silica dish. A gentle tapping of the bottom of the dish on a hard firebrick while it's cooling down is all that's needed due to the different rates of contractions of the metal and dish. You will hear an audible creaking noise as the dish cools and a gentle pop when it releases once cooled.

Steve

 

[dvontedlores]

Here's a short video of my 3.5kw unit melting ~2g of 99.9% fine Pd BBs into a single button. The video was filmed in real-time with no time lapse.



In the video I simply used a graphite crucible with no other lining. I do have larger crucible and linings, but they draw more amps than the 3.5kw unit will handle. I have not tried to melt larger amounts as I prefer the finish I get with torch melts for Pd.

Steve

Did your palladium turn out dark since you used a graphite crucible? I'm not sure how much of a difference it makes in reality

 

[lazersteve]

It turned out gray with slight peacock colored oxides directly out of the crucible. A quick boil in HCl and it was plain gray. For shining Pd I prefer the torch melt method. Purity is the same, luster of the button surface is the only difference.

Steve

 

[dvontedlores]

It turned out gray with slight peacock colored oxides directly out of the crucible. A quick boil in HCl and it was plain gray. For shining Pd I prefer the torch melt method. Purity is the same, luster of the button surface is the only difference.

Steve

How are you able to torch melt palladium without it absorbing oxygen?

 

[lazersteve]

Please read my post above with the Pd button that has a crystalline surface for those details.

Steve