Help Recovering Palladium Silver on Tungsten

[bhaden57]

I've got 125 lbs. + of Tungsten evaporator filaments used to evaporate our Pd/Ag alloy ( 20/80 % )in vacuum .
The precious metals are infused into the multi strand wire Tungsten filaments .
Several recycler/recovery companies have turned down recovery of this ( " not our specialty " , Ewww Tungsten ! " , " Not enough weight " , etc. " We'll give you 70% of lowest market price . " , " We'll settle at N % of market price at some vague future date .. " and so on ).
I'm looking for a fair price and fast turnaround .


This scrap is used wire filaments . They are multstrand Tungsten wire filaments used to evaporate the Pd/Ag alloy to coat it onto customer parts for our antigalling coatings.
The alloy is evaporated at high temperature and gets infused and fused into the wrapped , twisted Tungsten strands of the coiled wire basket filaments .
Each filament has about 0.05 - 0.15 grams of Pd/Ag alloy on it .

Other than doing it myself are there any trustworthy companies that offer recovery and purchase of the precious metals on this material ?
In addition we can sell the Tungsten scrap
I also have several pounds of grinding from inside the coating chambers that contains about 7.5 % Pd , 58% Ag and 1-2% Au .

It also has Ni , Cr , Cu and Fe in it but not much else .

I would appreciate any valid leads on authentic , honest companies that purchase these materials at a high enough and fast enough payout to make it worthwhile.

Alternatively , is the best method to use Nitric to digest the Pd and Ag from the Tungsten ?
Or use cold AR ?
Or another stripping method ?

What is the Best way to dissolve the ground-off metal powder ?
Ball mill then AR ?
Then how to get Gold out ?

Then for both materials , what is the best way to separate Pd , Ag and Au at high purity for reuse or resale ?

We generate about 20-80 lbs of grinding and 60-100 lbs of coated Tingsten per year .

I appreciate any valid leads .

 

[snoman701]

Location is pretty paramount.

You will not find someone to do this "fast".

 

[Palladium]

I've dealt with something like this before, except it was Tungsten silver alloys from a company that does drilling bits for major mining companies. They were getting bashed on the price of the Tungsten when they went to sell it because of the silver alloy brazing that remained after the drilling points were removed. They were losing money not only on the Tungsten, but also giving the silver alloy away and getting penalized on both. I doubt you will find anyone to buy it straight out. I had to develop an in-house process for them exactly because of the reasons you stated above. It can be done, but it's a long process and not that easy. You will take a hit on the price IF you can find someone to process it. Send me a pm if you don't find somebody and i'll see if i can help you out. I won't buy the metals, but i can process the materials to get the metals back. You can sell them then.

 

[Alondro]

Tungsten is a pain because in solution it forms polyatomic anions of varying size and reactivity. These can form all sorts of intercalation compounds and complexes with a bunch of metal ions.

If you had gold and platinum to recover, you might have a very hard time. But silver and palladium presents opportunities!

There are some ways to prevent tungsten from dissolving in the first place when recovering silver or palladium. Tungsten metal is quite unreactive to most acids at cool temperatures. So, 5M nitric kept cool (say, keep the reaction vessel in a water bath) might be able to gradually dissolve the silver and palladium without dissolving the tungsten itself.

There's also sulfuric. 60% sulfuric acid should dissolve silver and palladium in a temp of 80C. It will not touch tungsten at that temp.

Here's a site specializing in tungsten with a reactivity table: Chemical Resistance of Tungsten

What I don't know is if either of those methods forms a silver or palladium salt which will act as a catalyst to dissolve tungsten in these acids, the way copper(I) chloride can facilitate the dissolution of base metals in HCl. So a small test first is the wise option.

 

[Palladium]

Tungsten is a pain because in solution it forms polyatomic anions of varying size and reactivity. These can form all sorts of intercalation compounds and complexes with a bunch of metal ions.


There are some ways to prevent tungsten from dissolving in the first place when recovering silver or palladium. Tungsten metal is quite unreactive to most acids at cool temperatures. So, 5M nitric kept cool (say, keep the reaction vessel in a water bath) might be able to gradually dissolve the silver and palladium without dissolving the tungsten itself.

You sir are a very wise man! There's one or two other tricks i learned as a result of the process i designed for the company i mentioned above, but those are proprietary and makes me money so i won't reveal them here! I will say a whole lot of air is your friend!

 

[Alondro]

You sir are a very wise man! There's one or two other tricks i learned as a result of the process i designed for the company i mentioned above, but those are proprietary and makes me money so i won't reveal them here! I will say a whole lot of air is your friend!

Yeah, knowing the chemistry makes everything so much easier. Like I said, this was a simple method since there's no gold or platinum to deal with.

With Au and Pt, the chemicals that will dissolve them will ALSO dissolve the tungsten. Cold AR won't dissolve tungsten, but it won't do anything to Au or Pt either. HCl bleach releases chlorine, which will dissolve tungsten, as will the AP method.

I'd REALLY have to think hard to find a way around tungsten if there was Au or Pt.

 

[Palladium]

I wish sometimes i was a trained chemist. I'm a trial and error, monkey see monkey do kind of guy. I know the basics, but after that i get lost. It takes me a lottt of research from people wayyy smarter than me.

 

[Shark]

I resemble that remark!

 

[bhaden57]

Given the large differences in melting points between E,Ag and Pd is it possible to use a vacuum induction furnace to melt off everything except the W which could possibly be removed as a solid from the bottom of the melt ?

 

[Alondro]

Given the large differences in melting points between E,Ag and Pd is it possible to use a vacuum induction furnace to melt off everything except the W which could possibly be removed as a solid from the bottom of the melt ?

One would think that, BUT some metals will actually begin to DISSOLVE into compatible molten metals at much lower temps than its melting point. You see this a lot with copper and aluminum, for example. Even with liquid aluminum at a temp well below copper's melting point, some aluminum still combines with the copper to make brass on the surface of the copper. I used to play with this reaction in my teens when I had a simple forge at my grandparent's house.

 

[bhaden57]

I don't think Tungsten forms a eutectic with Pd or Ag given we use Tungsten filaments to evaporate the 80-20 Ag/Pd alloy as a daily process .
The Pd will form a slightly lower temp phase eutectic with Silver and evaporate as an alloy in high vacuum .
So theoretically the alloy could be melted off the Tungsten as an alloy .
I just don't have a vacuum induction furnace to try it .
If someone who has one wants to try it I can send a small sample.