How to melt palladium

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brjook

Well-known member
Joined
Aug 8, 2010
Messages
96
I tried and tried and all it done was sing to me .I know it absorbes oxygen and i tried to use as less as i could but no good .I don;t have access to a hydrogen torch so what to do?
 
Here is a post Lou made that might help you out.

Lou wrote:

Platinum bars are poured from zirconia crucibles that are "double bagged" inside an alumina crucible. The heavy wall alumina bears the weight of the ZrO2 crucible containing the Pt. Zirconia looses its strength after a few heats and must be replaced fairly often. Usually you have a "starter" plug or heal of platinum that soaks up the power because most melters are 10-12 kHz and won't heat powders for crap. Same thing for gold powder--most of the heat goes into the graphite or SiC crucible and melts it by conduction! It's a different story if you put a cylinder of gold in there. When the Pt plug melts you can add the sponge platinum. I much prefer to have not melted the material but have the sponge sit upon the bulk metal and heat, that way any moisture is steamed off.

Pd is much of the same, except atmosphere control is more important as it is considerably more gassy than platinum.
 
Thanks for the post but it didn't really help me any.All i was asking is there a way to melt Pd without a hydrogen oxygen torch?
 
brjook said:
Thanks for the post but it didn't really help me any.All i was asking is there a way to melt Pd without a hydrogen oxygen torch?
It can be melted with an oxy/acetylene torch, or natural gas and oxygen. I expect that you'd have difficulty with most other methods due to the relatively high melting temperature. Hydrogen is the recommended fuel, which eliminates the risk of forming carbides.

Harold
 
I got a oxy/Map gas tourch i use to melt gold with no problem.When i try to melt the Pd all it does is swell up and make a high pitched whinning sound the more i heat it .I tried to turn down the oxygen but it wouldn't melt it then .I have some 1 inch crucibles .Could i heat the outside of the crucible and not put the flame on the Pd .Would this work?
 
MAPP = MethylAcetylene-Propadiene Propane, this is a carbon based fuel, kind of a no no for Pt/Pd

I also find it hard to believe you can reach sufficient temperature for melting Pd just by heating the crucible.
 
brjook said:
I got a oxy/Map gas tourch i use to melt gold with no problem.When i try to melt the Pd all it does is swell up and make a high pitched whinning sound the more i heat it .I tried to turn down the oxygen but it wouldn't melt it then .I have some 1 inch crucibles .Could i heat the outside of the crucible and not put the flame on the Pd .Would this work?
I expect your problem is more rooted in lack of BTU's than temperature. Are you using the largest tip you have at your disposal? If you are, and you can buy an even larger one (rosebud, for example), that would likely work. I melted over a troy ounces of platinum with such a tip, using natural gas and oxygen. While I'm not sure I'm right, I expect that MAPP gas has much higher potential.

You likely can't melt by heating the crucible. There's too much heat being lost to the atmosphere. It likely would work in a furnace, however, but achieving that temperature is not easy. Induction is really the way to go for these metals, but it's somewhat out of reach for the hobbyist.

Harold
 
Thanks for the info Harold .I guess i will have to get a bigger tip .The one I am useing works great for gold but if i am going to do Palladium also i just rite if off as ths cost of advanceing .Also where can you sell palladium at ?
 
brjook said:
Also where can you sell palladium at ?
I'm likely not a good person to ask. My experiences in selling both my platinum and palladium left me with a very bad taste in my mouth---and I had a lot of each to sell.

You may find that Lou is willing to buy, but please understand that I am not speaking for him. I would recommend him highly if he's interested, however.

Harold
 
I'll buy your palladium. Don't bother melting it. It's easier for me to take a sample of the powder and run ICP-AES on it that way.

If you're trying to melt it, get a high back alumina crucible and preferably go at it with an oxyhydrogen torch. Any oxyfuel torch will easily make enough heat to melt platinum or palladium. It just depends on tip and flow rate. That's why I recommend a high back alumina melting dish so that it's much harder for your powder to blow away.

The reason why, the true reason, that carbon-based fuels like MAPP, acetylene, propane, and natural gas aren't recommended is this:

Palladium oxidizes. Platinum does not. You can usually get away melting platinum with oxyacetylene if you keep it lean at all times. You can't with palladium. Palladium has a problem that's kind of like silver's--it absorbs oxygen and fuel gases when molten and tends to spit if you don't know what you're doing. Remember well that these metals are catalytic--so any gas in a rich flame that hits the palladium is going to be split into hydrogen and carbon on the surface of the palladium. The carbon will migrate into the piece and give it a shiny gray-black look. Palladium has to be cooled below red heat in a reducing flame, and the only flame suitable for that is a hydrogen flame.


Lou
 
BR,

I am a Manufacturing Jeweler and cast and melt Pd everyday. Lots depends on several things: 1, What form is your Palladium in, Metal or sponge? 2. What are going to do with it after you melt it? Sell it or try to make jewelry? What we use is a 5kw Vacuum, Centrifugal, Induction Melter. Two major problems, first if it is in Powder or sponge, an Induction Melter is not going to melt it as the crystal structure is too small and it passes thru the powder and goes back into the coils of your $30,000+ induction melter. Nothing like frying the coils of a $30,000 machine to keep you from making the same mistake twice. If that sounds like experience talking, it is ! If it is metal form, unless you melt in under Argon or a strong vacuum, you will embrittle the metal and it will be crack to high heaven and be useless for jewelry. In order to melt with a torch, Most Platinum is Torch melted using Hydrogen & Oxygen which just happen to be the elements that Pd absorbs when hot.

Bottom line, If you got Palladium and you want to convert it to cash, send it Lou as he is the true expert and honest nice guy. The PGM's are best left to the guys that do it everyday and have the hundreds of thousands of dollars of equipment and know how to use it. Just some friendly advise from a guy who does it everyday.

Dan
 
I have no idea if this would work,or not.feel free to pick it to the bones.
I watched a documentry on net flicks about making carbon steel for viking sword.
they made a crucible of red clay,added the iron, carbon,and other materials.then sealed the crucible with more red clay.let it dry,then placed it in a wood fired furnace.used bellows to produce the required heat,and made carbon steel,in order to duplicate a sword.if the same air tight crucible were used to put pd in,and put in a furnace,would it work to melt pd?
john
 
Thanks for the recommendation, Dan (and Harold earlier on). I do appreciate it.

I've had the great fortune of working with Mr. Dement on palladium and its alloys and can say that it is a bugger to get right.

Here are the chief issues with palladium:

1. Forms an oxide before red heat (so called "peacocking")
2. Oxide disproportionates back into Pd and oxygen at higher temperature but reaches an equilibrium concentration of oxygen dissolved in the metal.
3. If you try to melt it under reducing conditions, the palladium can react with many of the refractories used in the crucible.
4. It is incompatible with carbon/graphite, silicon carbide, silica and to a lesser extent zirconia.
5. It should not be melted with carbonaceous fuels.
6. Even if you take care to melt the Pd with oxyhydrogen, you will still get a gassy metal unsuitable for jewelry castings.

It's an interesting metal. I can melt up sponge in a small LECO crucible into a button, cool it under hydrogen and get a shiny button, but have it not be fully dense due to all the hydrogen it absorbs. Melting it with a neutral or lean flame and it sparks all over.

Take home message: it shouldn't be torch melted. I think the only way to melt the powder reliably is a higher frequency vacuum induction furnace, preferably one where the power is ramped up slowly while pumping down. Too much power and the powder can fly out of the crucible. Too fast a heat up and any oxygen and/or hydrogen present will react with the metal.
 
Thank you all of you for the recommendation & practical information! :mrgreen:
 
Here's a good demo of how not to melt Pd...
See from: 5:20
[youtube]http://www.youtube.com/watch?v=r9sTVx_YV5A[/youtube]
 
Cool video Sam, that's what I would call a "pipe"! :mrgreen:

Göran
 
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