# 1930's Platinum???



## Chondrule (Feb 11, 2015)

Hi again folks,

I’m back so soon with another project because I’d been working on this one simultaneously as I did the “Unknown Contaminant” one you may have checked out.

A few years ago when I first started doing refining, I happened to purchase a very interesting old light bulb type of thing at a swap meet, I purchased it specifically because I thought it might contain precious metals and figured the $5 I paid for it was well worth the gamble.

Back when I got it, I did a little searching to figure out exactly what it was and any specifics about it, but didn’t find much, all I managed to establish was that the company who made it existed in the late 30’s and early 40’s and that this thing was some sort of heavy duty light bulb.

The thing is, at the time, I didn’t care a whole lot about what it was, I was more anxious to break it open and get to the contents, but now I’m regretting not having documented it before destroying it, in other words I have no image to show you, so all I can say is, it was about 2” in diameter, about 8” long, and made of clear glass with a lot of wires, meshes, and antenna like components inside.

What I salvaged from the bulb was: four wires of 1/16” diameter, two metal plates 1/64”x1/2”x2”, four rods of 1/32” diameter by 3/4” long, and a sort of mesh type of thing suspended between rods which I think was the filament. The four wires connected the two plates to the four rods, the means of joining being soldering, the filament was separate from these other parts and I don’t remember how it related to them.

Shown below are all the parts, except the filament, and some pieces of silver shot for color comparison.



Keep in mind that what’s shown is far from original condition, for one thing I cut the plates and rods off the ends of the wires, but more importantly, I’ve abused the hell out of this stuff in the few years since I first acquired the bulb. What you’re looking at are the pieces readied and sized to fit the mouth of the Erlenmeyer. The wires in particular have taken the most abuse, they’ve been repeatedly folded completely over and then straightened out again, they’ve been coiled up into tight spirals about the size of a nickel and straightened out again. What I’m getting at is how extremely malleable this stuff was, not malleable like a roll of solder you’d get from the hardware store, but malleable like you’d expect a platinum wire to feel like, and they never showed the slightest hint of ever wanting to break.

Besides all the folding, coiling, spiraling, and straightening of the wires, I also hammered one of them and there was no sign of cracking or splitting. I could’ve hammered until it was as thin as aluminum foil, but that wasn’t needed, I had seen enough, and the result is shown below in the next two images.




Seen also in the above two images are the results of another test I did with platinum in mind, the wire on the right was heated using a mapp gas torch, and the torch struggled, it would just get the wire to start to melt and that’s it. Obviously I never got the material to fully melt, not even enough to get the coils to stick together (I had it coiled up like a spring, with coils touching), for afterwards I pulled it apart and saw that the coils never adhered to one another.

The high melting point wasn’t the only platinum supportive conclusion that I arrived at with the melting test, the white light produced by the coil was intense. I learned the hard way that welders goggles should be worn when melting this stuff, I could see the white spots burned into my eyes, see them even in broad daylight, and it took till the next day before they went away. I never experienced anything like this before because I’ve never worked with PGM’s, I fear I may pay for this in the long run since my eyes are already hammered from doing similar stupid stuff in the past.

Besides the malleability, the high melting point, the intense light given off when heated, and some of the other indications such as the color of the metal in general and the color of the material after being heated, I also can add to this list that nitric had no effect whatsoever on it. Up until I did the nitric, palladium was still a contender, but supposedly palladium is attacked by nitric, thus platinum is still my number one candidate.

Something contrary to my platinum assumptions is that the parts are fairly attracted by a high quality, strong, neodymium magnet, the attraction is unmistakable. This lead me to think that there was a fair amount of nickel present, yet the nitric had no effect, so I don’t know what to think about this, the items are definitely not plated for the wires had been cut off and had exposed ends.

The weight of the salvaged parts was 17.98g, and here’s the solution after transferring from the erlenmeyer, at this point it’s been filtered, evaporated, and the nitric killed, at least I think it was killed as you will find out.



Two things about this solution, first it’s green, which I was expecting since I thought nickel might be involved, and second, I used an erlenmeyer because I was expecting it to be a long time on the stove, and sure enough it took twice as long to dissolve than the batch of gold I had started simultaneously. I thought this long in duration cook time was another promising aspect indicating platinum.

One thing deserving pointing out concerning the evaporation, there seemed to be way too much liquid still present, in other words I never got to the syrupy consistency I had wanted, unexpectedly and seemingly way to prematurely, the liquid suddenly turned into a mass of crystals. I added a good amount of hydrochloric, and a little water, and it took some effort to get the stubborn crystals to dissolve, but once they did, I then evaporated again as best I could before pulling it off the stove a little early in fear of getting the crystals back again. I don’t know what, if anything, these crystals might mean, maybe they are indicative of something gone wild like the girls I use to mess with, but I do know that I feel a little uncomfortable knowing I may not have killed the nitric.

Finally after all that setting of the stage, now I can get to my problem, that being the addition of ammonium chloride, it produced nothing, not even a wimpy little fizzle. The addition by the way, it was done to 5ml of solution, not done to the whole beaker full. I guess it’s possible that I never killed the nitric because of the crystal growth problem and thus the negative result I got from the ammonium chloride, so as I’m writing this now, I’ve got the solution back on the stove but this time taking it down at an excruciatingly slow rate, maybe this way I can get it to the syrup I didn’t achieve before, maybe this will make a difference when I go to try the ammonium chloride again.

In the mean time I did a test of the aqua regia, what you’re looking at is a few drops of it on a filter paper with a drop of stannous solution in the middle. Doing these stannous tests is something I definitely have no confidence or experience with, so what do you guys think?



After seeing no result with the ammonium chloride, I thought I’d try and see just what would precipitate, so I took the 5ml of the solution and sprinkled in a little SMB, and again nothing, I then put a length of copper wire, and again nothing, so I added a few drops of nitric and started getting a reaction. The addition of copper wire and nitric produced just a whisper of black fluffy residue, very light weight, but that’s it, so oh well, so much for messing around.

By the way, having never worked with platinum before, thus not with ammonium chloride either, is it normal that this stuff is hard to dissolve in water, and that it gets cold? I had to put it on the stove to get it to fully dissolve, which prompts me to ask this too, should I have added it to my aqua regia solution when both were about as hot as I could get them, was it a mistake to have done it at room temperature?

I must say, if the ammonium chloride had precipitated like I was expecting, you’d not be hearing from me right now, so besides comments about the stannous test results which I can hardly wait to hear, anything you can say about any of the other stuff I went over will be appreciated and given a lot of consideration.

I started off with 17.98g of material to dissolve, it all was completely dissolved, in fact there wasn’t even any residue that got filtered out when I transferred the contents from the erlenmeyer to the beaker, everything dissolved except the four rods, they remained intact.

Oooops, I’ve reached my limit of five images, to be continued..........


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## Chondrule (Feb 11, 2015)

So here’s the rods.



These rods are interesting, not only because they survived the aqua regia absolutely intact, but now that they’re separate and singled out, their weight is easily noticed, and they’re heavy. Their weight is 1.25g by the way, so in solution I still have 16.73g of unaccounted for material I still need to figure out how to precipitate, with the help of you’all of course.

In the first image I provided for this topic, these rods are at the top, they’re not so easily seen in that image for comparison to this last image, but the black coloration is original, it’s not a product of the aqua regia. The pristine ends of these rods were exposed only when the platinum wires joined there were dissolved away, these ends are the true color of the metal that they’re made from. Notice also that three of the rods have their very ends broken off, ends which I didn’t include in the image because they wouldn’t cooperate and stay put, but these breaks are an indication that the material they’re made from is brittle, these broken ends were hidden and held together by the molten wire joined there, again not something due to the aqua regia.

Originally I didn’t care much about these rods, I figured they’d disappear into solution and I’d never have to give them another thought, but now they demand more attention, I’ll have to give them a lot more consideration at some point for maybe they’re iridium. At this point, all I can say for sure is that they’re not attracted to a magnet, so that’s a plus, and they’re distinctly heavy, easily comparable to gold. These rods should be left for another time, another topic, I just think they’re interesting and since they were part of what I’ve got in solution, thought they deserved some mention.

So to sum this all up, I thought I was dealing with platinum but now I’m not so sure, what do you guys think, was my diagnosis wrong, did I screw up the process somehow, what does the stannous test say?


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## jason_recliner (Feb 12, 2015)

Chondrule said:


> So to sum this all up, I thought I was dealing with platinum but now I’m not so sure, what do you guys think, was my diagnosis wrong, did I screw up the process somehow, what does the stannous test say?


Interesting read, and one I will enjoy following.
In my inexperienced opinion, it does look like a platinum result. You can see a sample here: first post, item #10. http://goldrefiningforum.com/phpBB3/viewtopic.php?t=562


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## kurtak (Feb 12, 2015)

Chondrule said:


> So to sum this all up, I thought I was dealing with platinum but now I’m not so sure, what do you guys think, was my diagnosis wrong, did I screw up the process somehow, what does the stannous test say?



Stannous is the true test for Pt --- & yours does "not" look like a Pt positive test

There are other metals &/or alloys that are resistant to AR besides PGMs (Ir, Os, Rh & Ru being the PGMs resistant to AR)

There are other metals &/or alloys that are high temp resistant so heating &/or trying to melt with a torch tells you nothing 

Pt (&/or any of the 6 PGMs) will not melt - at all - with a MAPP torch - not even as a fine divided sponge let alone solid metal

Pt when heated to red hot - then cooled - will look just like it did before the heat was applied - there will be no discoloration &/or bluing (reference here is to the pins which are discolored by heat)

Bending & smashing tells you "nothing" - doing that as a way of testing is a total waste of time --- applying heat is for the most part the same - a waste of time as a test --- other then in the case of Pt in which case heat could indicate that it "might" be Pt

Why would they use PGMs in a bulb when other cheaper metals will in most cases do the job :?: 

Kurt


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## Lou (Feb 12, 2015)

These are evaporation coils made of tungsten or perhaps molybdenum, similar to a light bulb but not quite. Although platinum was once used as a filament (and heating element in resistance furnaces, actually still used is a non-aging PtRh alloy), that is not the application these heavy coils were used for--they were used for thermal evaporation. The ribbon is probably part of a Mo heat shield.

These coils will occasionally have Pt but usually are gold, palladium, or silver and are very good to scrap, sometimes running into the hundreds of dollars per pound. They are used for physical vapor deposition of these metals onto a substrate (like silicon) before imaging in an electron microscope. In a high vacuum, the coils resistively heat up with high current, the metal pellet (evaporation source) melts and wets the tungsten (which has a low vapor pressure at say, 1500*C), increasing its surface area, and the atoms of metal are deposited onto a substrate. 

http://www.lesker.com/newweb/menu_evapsources.cfm

It looks like nickel was used as the evaporation material, hence your green solution. Depending on how old the nickel may be, it might have been contaminated with platinum. Molybdenum does dissolve in AR and nitric acid, tungsten, however, does not appreciably dissolve in aqua regia, even hot it is slow. A quick test for tungsten is to put one of these in 30% peroxide and look for fizzing and a yellow solution of polytungstic acid. A quick test for Mo is, under a great draft, to heat these coils bright red in an oxidizing flame--they will burn to give a sublimate which may collected on a cool glass surface (first yellow, then changes to white, much like ZnO) and is pure MoO3. This substance dissolves in dilute akali to give an alkali molybdate. Tungsten oxide is less volatile. 

Molybdenum (VI) in chloride media (sulfate will not) will show an orange color on stannous, a false positive for Pt.


This type of scrap is certainly worth looking for--my company process much gold/palladium and silver-copper brazed vacuum systems, and sometimes these little guys are the cherry on top


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## Chondrule (Feb 12, 2015)

Good stuff you guys, thanks for the input.
You all are light years ahead of me, it's going to take quite an effort to understand what you've said, but even then I'll be lucky if I can get 10% of it.
Never the less, I promise you that you haven't wasted your time, I'll be studying the heck out of the information.
I'll let you all know if I get anywhere with this project.
Thanks


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## kurtak (Feb 14, 2015)

Very interesting read Lou - thanks for posting

Kurt


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## Chondrule (Feb 23, 2015)

It's been a comedy of errors working with this green solution, too much to try and explain so I'll keep this as limited as possible.

My first attempt at evaporation and killing the nitric was sketchy, I produced crystals and had to abort the process, but now however, at least this step was accomplished after a second, painfully slow try. Now that I knew the nitric was killed, I repeated the addition of ammonium chloride and again got no result, and the same happened with SMB, nothing.

Getting nowhere, I then tried copper, and this ended up the same, nothing. The thing about this try to get something to precipitate with copper, the solution was super concentrated since this was needed when I had added the ammonium chloride, but now in hindsight I'm thinking the copper may have worked if I had diluted with water, but I'll never know now.

Having failed with the copper, I decided to go with zinc powder, and finally got a reaction. I added the zinc and left it for a day, then added some more and left that for a day, it took so long because I had to stir every few hours or so, it took forever it seemed for the process to complete and get no reaction after stirring. After that I boiled the sediment in hydrochloric to get rid of any excess zinc, then boiled in water to rinse.

So that's where I stand now, with this dark chocolate brown, very fine grained stuff that I still don't know what it is.



I haven't decided what to do with this stuff, do I melt it and make shot, do I dissolve it again in aqua regia and re-refine it?

One thing I do know, whatever was present that made the original material stick strongly to a magnet, that material has been eliminated, so at least that small step was accomplished. Also, never did I run across any silver, if that tells anyone anything.

So what do you guys think now, any suggestions?


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## Lou (Feb 23, 2015)

I don't think there are any precious metals. I think what you've done is remove nickel from the refractory metals.


Lou


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## Chondrule (Feb 25, 2015)

I should've known the second I added ammonium chloride for the first time that what I was processing was worthless, but I needed to learn and that's exactly what happened by beating this dead horse.
You summed it up perfectly Lou, and it amazes me that you knew exactly what I was dealing with without even seeing what was going on first hand.
So even though I didn't get the Platinum I was hoping for, the stuff I learned along the way was just as valuable, this wasn't all for nothing.
The brown powder (refractory metal) is now in the garbage, now I can move on to something else.


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## Lou (Feb 25, 2015)

Not my first rodeo with these things.

Just because these were nickel evaporation sources doesn't mean you shouldn't pursue more of this material--I'm telling you, if you find some that have Pd or Ag or Au...you'll be a happy camper!


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## Chondrule (Feb 25, 2015)

Thanks Lou for the vote of confidence, your time, and your help, without it, people such as I would get nowhere.


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## lazersteve (Mar 30, 2015)

As a general rule of thumb when working with unknown alloys, get an XRF of the starting material before jumping into chemical process. An XRF reading won't give you the exact make up of the alloy, but it will give you very good clues as to where to begin your process, or what not to process if the reading do not show any precious metals.

You can contact local scrap yards, precious metal buyers, or college labs to get access to an XRF reading if you are like me and do not own an XRF. Save up samples of your unknown solids and make a trip with your sample(s) to the place that has an XRF near you. Make sure to call ahead and confirm that it is ok for you to get the samples run. It only takes a few minutes per sample and is an excellent way to get/keep your bearings when processing unknown scrap types or when identifying unknown left overs.

Keep good lab notes with photos of the unknowns so that you can id the same scrap in the future if you encounter it again.

Steve


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