# platinum melting



## ms32462 (Nov 27, 2011)

i seen on steves video that he uses hydrogen/ oxy mixture. it sounds good and works but getting it might be expensive . what do other people use who is some what on a limited budget. thanks


----------



## notch (Nov 27, 2011)

ms32462 said:


> i seen on steves video that he uses hydrogen/ oxy mixture. it sounds good and works but getting it might be expensive . what do other people use who is some what on a limited budget. thanks



You have to use Oxygen. No getting around that.


----------



## Joeforbes (Nov 27, 2011)

Hydro-Carbon based gases such as propane and acetylene will also contaminate Platinum group metals. The Platinum will absorb the Carbon.

Unless you really need to melt the Platinum, or you are just doing it as a hobby and would like a button, the un-melted sponge is worth just as much at the refinery.


----------



## samuel-a (Nov 27, 2011)

Joeforbes said:


> The Platinum will absorb the Carbon.



That's not true.

Non of the heavier elements of the family (Pt,Ir, Os) will form Carbides at these conditions, nither will absorb Oxygen. That in includes Gold as well.
With the lighter metals of the family (Pd, Rh, Ru), With the exeption of Rh, Carbides and oxides does form on the surface to produce brown to black(ish) coat. Also, Pd and Ag (just above Au) absorb Oxygen and spit it out while, and after the melt. I do not know about Ru.

Maybe Lou or Lino could shed some more light and correct me if i'm wrong with something here.


----------



## lazersteve (Nov 28, 2011)

Carbon based gases can form carbonyls with Pt, Ir, and Rh.

Steve


----------



## Joeforbes (Nov 28, 2011)

Pt3(CO)6


----------



## Duxthe1 (Nov 29, 2011)

FWIW, I recently bought a small torch kit from Lowe's for 60$. It is an Oxy / Mapp setup that uses conventional hardware store mapp bottles and a similar reverse thread Oxy bottle. It does get hot enough to melt platinum, I just melted some sponge into buttons this past weekend with little effort. It's an OK entry level setup but I do have a few gripes. First off the Oxy bottle is the same size as a conventional 16oz propane tank only holds 2.1oz of O2. I wouldn't be peeved about that but they are 10$ a pop and at a decent flow would be lucky to last 10 mins. Ok for a hobby-ist like myself but in a production environment it wouldn't make economical sense. I'm already thinking about trying to use the setup with compressed air instead of O2. My second gripe is that it is a pretty cheap setup. It comes with both bottles so about 15$ is accounted for but for the remaining 45$ you only get a very basic torch, 4 ft of hose, a striker, and the connectors for two bottles with rather rudimentary valves.

That said, you can melt platinum for 60$, which isn't bad compared to a full fledged torch rig. The key is having everything set and ready to go so that as soon as the torch is lit your work is heating. You don't want to be dinking around with that 10$ bottle of O2 burning up fast.


----------



## samuel-a (Dec 2, 2011)

lazersteve said:


> Carbon based gases can form carbonyls with Pt, Ir, and Rh.
> 
> Steve



FWIW, with enough O2 to burn the gas, it's not likely to happen.

I'm melting Pt with Oxy/propane , and never had a brittle or darkened product... 
Then again... what do i know...


----------



## Harold_V (Dec 3, 2011)

samuel-a said:


> lazersteve said:
> 
> 
> > Carbon based gases can form carbonyls with Pt, Ir, and Rh.
> ...


You're right, but with an oxy/acetylene torch, it's really easy to set with a reducing flame. Avoid that and odds are pretty good you'll have no problems. That's key to success, unlike working with silver and gold alloy. A slightly reducing flame is to advantage there, but (can be) death on the platinum metals. 

Harold


----------



## Lou (Dec 3, 2011)

The flame choice is more of an issue with Pd and Rh, but who really melts those with torch anyway? You shouldn't use an oxidizing flame on either of them because they both spatter. A neutral H2/O2 flame is preferred because it's cleaner and one can cool the metal under H2 (especially nice for Pd, which otherwise turns colors). In practice, they're all melted in a controlled atmosphere induction furnace.


----------



## lazersteve (Dec 3, 2011)

I find that following Hokes guidelines for melting PGMs is the best choice. A variety of melting techniques will work for PGMs, but cutting corners can lead to losses.

I have melted PGMs with a wide variety of gases and the oxy/hydrogen rig gives the best results with little or no losses. I have observed losses when melting Pt with carbon based gas and oxygen.

Just like other steps in the refining processes; there are many ways that 'will work', but there are very specific ways which work best. Anyone serious about refining PGMs needs a hydrogen rig in my opinion. There are good reasons why all of the texts on PGMs refer to melting with hydrogen.

Steve


----------



## kadriver (Dec 26, 2011)

Where is the best place to get a hydrogen rig?


----------



## element47 (Dec 27, 2011)

> Ok for a hobby-ist like myself but in a production environment it wouldn't make economical sense. I'm already thinking about trying to use the setup with compressed air instead of O2.



I don't think that's going to work that well. I suppose you could try it; I never have done so. For one, compressed air is only about 21% oxygen. That means you are going to really have to blast the "air" feed (at 5x its normal flow rate) to get type of combustion implied by however much fuel is delivered out of the torch fuel orifice. I would imagine that will blast unmelted powders and pieces of PM out of your melting dish. Indeed, the gas velocity may be so much that a flame cannot even be sustained without blowing out. For two, the nitrogen in air played on molten PMs (meaning; heated to those temperatures) might cause a reaction that I can't imagine being helpful. Last problem is that without good filtering, compressed air often has oil in it. I have not tried what you are suggesting so I can't say it will fail based upon direct experience, but I would suspect it will be problematical. If you want to melt PMs on a regular basis, even in modest quantities, I think you eventually have to go with a real oxygen bottle, which should last a heck of a long time. (of course, depending upon size) There is no question that buying MAPP and (especially) oxygen in Bernz-o-matic sized cylinders is frightfully expensive.


----------



## kadriver (Dec 28, 2011)

I found a source for a hydrogen torch:

http://www.riogrande.com/Product/Smith-Hydrogen-Platinum-Casting-Torch-System/500323

I have checked with Airgas and they keep a few bottles of hydrogen for this torch.

I do not see any gages with this set, just hose and torch.

Is this the proper rig needed to melt platinum?

Thank you - kadriver


----------



## kadriver (Dec 28, 2011)

I found a regulator on ebay:

http://www.ebay.com/itm/Smith-Equipment-30-100-350-Series-30-Hydrogen-Regulator-/330662043823?pt=LH_DefaultDomain_0&hash=item4cfcfe60af

Are these the items I need for a proper platinum melting torch?


----------



## butcher (Dec 29, 2011)

Some other price on this:
http://www.bakersgas.com/SMI30-100-350.html#?w=500

http://store.cyberweld.com/smhyreliduh1.html


----------



## kadriver (Dec 29, 2011)

I see you found a better price - thanks butcher.


----------

