# Platinum sponge from hydrazine sulfate



## Tomodachi (Jul 5, 2010)

Hey guys,
I have been struggling to get platinum sponge using hydrazine sulfate. I understand that I could just calcine the ammonium platinum chloride salt to get the sponge, but I'm under the impression that it can be done quickly & efficiently with hydrazine and that's what i'm after.

Here's what I'm doing... Pt, Pd, Rh mix from cats was Reduced previously with zinc then redisolved in AR. Rh was then seperated out as greyish white powder leaving Pt & Pd in solution. The first time through I was curious to see how the metals would reduce so I increased the PH with ammonia and then sprinkled in some hydrazine sulfate, almost immediatly the solution darkened to a black color and within a min or two the particles began floculating. So now I was again left with the black powder that looked similar to the stuff that the zinc originally precipitated.

In a new batch I followed the same proccedure as before but this time I precipitated the platinum with NH4Cl. After filtering the orange-yellow salt I washed it a few times in the filter with NH4Cl solution. Fresh stannous chloride was showing positive results throughout all of my testing. After dissolving the Pt salts in water with a ph of about 6 at room temp. I got the same precipitant, a difficult to work with black powder. 

My qustion is, how do I get the heavy, easy to work with, grey platinum sponge when reducing with hydrazine sulfate?

Any suggestions/corrections would be very much appreciated, I enjoy details!
Thanks for any help!
Greg


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## Platdigger (Jul 5, 2010)

Try adjusting the ph with sodium hydroxide.


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## lazersteve (Jul 5, 2010)

Greg,

I've never had any luck getting sponge from hydrazine, only black moss at best.

For a good sponge calcine the Pt salt and then sinister the sponge under hydrogen to a coherent mass. Or you can continue heating to fuse the Pt to a bead as seen on my Pt DVD.

Steve


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## 4metals (Jul 5, 2010)

Reduction of Ammonium Chloroplatinate to Platinum metal using Hydrazine hydrate

Add DI water to the Pt salts to yield 1 gram of platinum (which equals 2.3 grams of ammonium chloroplatinate) per 20 ml of water.
example 100 grams of ammonium chloroplatinate divided by 2.3 = 43.478 grams x 20 ml/g Pt equals 869.5 ml 

Heat the water salt suspension th 45 degrees C and stir well

Prepare s solution of Hydrazine Hydrate by adding 4.1 ml of Hydrazine Hydrate (85%) to 50 ml of DI water.

Every 50 ml of the Hydrazine Hydrate solution will reduce 10 grams of platinum metal.

Allow the metal to settle and decant the solution, wash and dry the metallic platinum. 

If you are torch melting this powder be careful as it is easy to blow away all of your hard work.


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## Tomodachi (Jul 5, 2010)

Thanks for the replys.

Steve,
If I eventually just can't figure it out I will most certainly be using the method you used in your pt/pd dvd, it's great btw! I'm just determined at this point to do it the hydrazine route 

4metals,
Am I right in assuming the deionized water is helping it to flocculate better? Also, will I have the same results if I desolve hydrazine sulfate into some di water, or is it nesessary to be using the freebased hydrate form?


Thanks
Greg


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## Lou (Jul 10, 2010)

4metals procedure does work, but I usually add about 50 mL of conc. ammonia per liter, with subsequent additions as needed. As you add your hydrazine sulfate solution, you'll see the evolution of nitrogen gas. If you're getting a finely divided black precipitate you're 1.) going too fast with the additions, 2.) your ammonium hexachloroplatinate is impure, 3.) you're too hot. You should get a heavy gray sand if done properly (this is with hydrazine hydrate, or its common salts). When you start adding you're reducing agent, be it zinc, hydrazine, formic acid, or whatever else you may be using, you will see a sickly green hue to the solution right before the metal begins flocculating. Also, make sure you boil you're solution after the last addition--doing so will help the particles agglomerate. IF you're still messing it up, add half a teaspoon of cornstarch when you boil, this will help it all settle. That can be removed with oxygen in a tube furnace, or burned away if you make casting grain. 

Keep away from ammonium formate and borohydride--those two are the worst at giving super fine blacks that can take fire and take forever to filter. hydrazine hydrochloride + ammonia is the way to go if you're after sponge. No rinsing needed.

Any further questions, ask me! I've reduced platinum with many reducing agents, and hydrazine is my second favorite.


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## 4metals (Jul 10, 2010)

Lou wrote;


> Any further questions, ask me! I've reduced platinum with many reducing agents, and hydrazine is my second favorite.



And your favorite is?


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## skippy (Jul 10, 2010)

Lou, how do you like formic acid? I can get formic acid at a very reasonable price from an apiary supply place.


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## Lou (Jul 10, 2010)

A combination of careful heating and hydrogen gas done in a quartz tube with a removable quartz frit on one end in a tube furnace. 

Doing it this way makes it much easier to remove all of the ammonium chloride (or chlorine gas if you start from a halide). A separate tube for Pt, Pd, Ir, Rh. No acids, no filtration, simply load the tube, set the PID to its preprogrammed ramp/cycle and open the regulator when at temperature, close the regulator after a certain amount of time (material & compound dependent), and open the valve to the vacuum as it cools back to RT. In a large 15 cm tube, one can reduce many kilograms of ammonium hexachloroplatinate, palladate, rhodate, osmate, etc. (it is general). The vacuum is applied as it is cooled to ensure that there is no hydrogen left adsorbed onto the surface. Several years back, I had rhenium sponge take light after opening the cool tube. Quite an experience! I've done the whole thing with just straight calcination. Works fine for platinum if you go nice and easy, and to a lesser extent Pd and Rh (I usually let them cool under a soft H2 flame). 


There are the most minimal PM losses this way, and all the platinum group can be reduced cleanly and very cheaply. Mole for mole, hydrogen is very cheap. The quartz tube is several hundred dollars, the regulator several hundred dollars, the vacuum pump, a thousand, the T cylinder is three hundred or so, and $28 to fill, the rest of the glass (which may be borosilicate), several hundred dollars, and the tube furnace, several thousand dollars. For about ten thousand dollars, you can have a setup that can reduce EVERY platinum group metal (as well as produce their halides, oxides, and various other salts and compounds for a value-added product). The versatility is what makes it so useful. Hydrazine and its salts work great, but handling hydrazine gets old, and even the relatively benign sulfate is still irksome. I've long since grown tired of aqueous work with the platinum group. Beaker and flask are fine for ~10-20 oz, but anymore, and it's easier to do it in a tube furnace rather than get a sealed glass-lined Pfaulder kettle (and much less reagent intensive). Being frank, the oxidation is easier on scrap material too (especially for rhodium).


Formic acid works quite well for platinum, palladium, and to a lesser extent rhodium if the proper precautions and care is taken. I usually take whatever salt, dissolve it in a minimum quantity of water, and then add ammonia. The solution may be clear or turbid. I then heat, and add small (50 mL) portions of conc. formic acid. You will see ebullition as CO, CO2 and H2 gas is produced. It should be pH 6.5 or above to work correctly. Boil away (80-90*C) and go until all trace of green is gone (or light brown for Rh). It will be inky black when all is reduced , but will gray as you boil and the particles stick together. Filter on a quartz frit.* Filtering PGM blacks is a pain in the butt, so avoid them at all costs. They quickly clog the frits, and vacuum filtration goes quite slow especially if you have gallons of solution. Filtering with a vacuum setup and fritted glass is a proposition only for very high purity metals in 10-30 oz. quantities, any more than that, and a dry method using the tube furnace is preferred. 

Ammonium formate solutions are old hat insofar as organic and inorganic chemistry goes...


*Quartz frits are somewhat of an investment, but when I do not want contaminants or extra steps, they are useful. They may be cleaned with aqua regia, or with conc. sulfuric acid, and you should have one for each metal, clearly marked (ask the glassblower) to avoid cross contamination).


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## 4metals (Jul 10, 2010)

Nice, no waste and no oxides. You're right if you end up with PdO you have to heat it to get rid of it anyway. I would have some serious reservations about having just any operator doing the reductions. In the refining of karat scrap the Pt and Pd is present in ounces per thousand ounces of scrap in most cases. For those quantities I think wet chemistry would be simpler. 

Materials with high levels of PGM's are a different story. Versatility is nice.


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## Lou (Jul 10, 2010)

I absolutely agree! If your game is karat scrap where they accumulate only slowly, by all means, aqueous methods are the best.

If, however, you're buying thermocouples, platinum compounds, spent research catalysts, and concentrates from catalytic converters, and your incoming purity is say 90% of a given metal, then this method compliments aqueous methods quite well insofar as reduction and conservation of purity are concerned. It's suited to an operation that strictly processes PGMs in high purity. 

I needn't tell you that tube furnace processing of rhodium, osmium, rhenium and ruthenium is THE only sensible way to go. Putzing around with them in solution is a certain way to have them tied up in your waste stream effluent for weeks! Keeping them concentrated and purifying with selective gas phase chemistry is a way to keep down first pass losses.


Lou


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## lazersteve (Jul 10, 2010)

Lou,

Your posts above have really got me inspired to get my tube furnace going full speed!

It's a shame I've had it ready to go for nearly a year and haven't reduced a single compound in it yet.  As I mentioned to you before, I'm seriously lacking a proper place to set it up and put it to work. I know mine is only a 65 mm x 610 mm tube, but I feel it will be just right for me!

One note on this subject: Anyone thinking about the tube furnace will need the proper power source to run the thing also. I know it sounds obvious, but some people jump in head first the first time and don't realize *all* of the requirements of operating equipment like this. 

I'm very interested in trying my hand at stripping gold plated scrap with it.

Hopefully one day very soon, I'll graduate to using the tube furnace exclusively!

Thanks for all of your guidance and wisdom Lou.

Steve


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## qst42know (Jul 10, 2010)

I sure would like to see what this tube furnace looks like.

Do you have a photo?


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## lazersteve (Jul 10, 2010)

Here's one of it disassembled :







And here's the tube sections next to a fat marker for size comparison:






There is a bunch of other hardware and glassware that is not in the photos.

I had the tube fabricated from two 24" x 64 mm ID fused quartz tubes and two fused quartz 24/40 joints I purchased on eBay. I wish I had done it a little differently, but it should work and I was on a budget. Turns out the fabrication work cost five times what the glassware did, but it was done professionally and I feel good about that. One day I'll fed it some scrap catalytics and post the video.

Steve


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## skippy (Jul 11, 2010)

LOL word of the day: ebullition
thanks Lou!


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## skippy (Jul 11, 2010)

Steve, is that white fluffy cylinder a homebuild tube furnace? Care to share any details?


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## lazersteve (Jul 11, 2010)

skippy said:


> Steve, is that white fluffy cylinder a homebuild tube furnace? Care to share any details?



Yes I built it myself.

The fluffy white stuff is the ceramic heater tube wrapped in koawool. The straps hold the wool in place around the ceramic tube. The tube assembly gets inserted inside the steel housing and the thermocouple is wired to the PID in the black control box.

The long fused quartz reaction tube gets inserted into the ceramic tube. The short fused quartz collection tube is attached to the long tube after the charge is place in the longer tube. The reaction tube is the one that is heated and the collection tube is the one where your values condense.

Search the forum for tube furnace for more details.

Steve


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## skippy (Jul 11, 2010)

Steve, it looks good! Those two leads sticking out on the end, what are they? They look something like sheathed stove elements. I'm building a tube furnace too. I'll have to take some pictures when its done.
I'm looking to try the Quartz tube process too. I have a glass blower where I live who will work for $40 per hour, which is amazing, because I can't even get anyone to work on my car for that :lol:


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## lazersteve (Jul 11, 2010)

skippy said:


> Those two leads sticking out on the end, what are they?



They are actually insulating ceramic tubing standoffs (1/8" ID x 1/4" OD) around the element wire. The wire is terminated into a straight brass coupling with set screws (Lowes electrical section) to hold the standoff in place and provide a convenient hook up for the element power feed.

Steve


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## 4metals (Jul 13, 2010)

Steve said;


> The reaction tube is the one that is heated and the collection tube is the one where your values condense.



A little clarification here please, I've calcined a lot of platinum salts in my day in furnaces without a reducing atmosphere. The values never volatilized and re-condensed and I wonder why they would in your rig? 

I have never been a big fan of filling those finger shaped silica boats with metal salts for reduction. Plus there is a limited capacity in a small diameter tube. Factor in that I've become frugal in my old age and I have some ideas for building a atmospheric reducing chamber that will fit into my assay furnace. 

I spoke to my glassblower and he can make me a 8" diameter 6" deep quartz glass chamber with the tubes I've sketched in the drawing. The top will have a tapered glass joint lid to open the top fully. I would mount this on a replacement door / shelf arrangement which I can slide into my assay oven. Once loaded with a silica tray full of salts it can be slid into place while the kiln door remains open and out of the way. Then I can hook up a vacuum to the top an a hydrogen cylinder to the bottom. 

This will out-gas some nasty chlorine fumes so I'd use a venturi in a closed loop to pull vacuum and scrub the fume in the water at the same time. The top of the venturi tank can go to the exhaust. Now I can heat the oven and when it gets to temperature (around 200 C) turn on the hydrogen gas and evacuate at the same time with the vacuum.

This should work on both small and relatively large lots and since I don't need a tube furnace and controller, should be 4 or 5 thousand cheaper than Lou's estimate.

Opinions?


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## skippy (Jul 14, 2010)

4metals, I think your puzzlement stems from there are now two different uses being discussed here - using the tube for the reduction of accumulated PGM compounds, and using the tube setup to extract PGMs as halide from substrates. I believe Steve was outlining the use of the tube furnace setup for the later.


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## skippy (Jul 14, 2010)

Neat plan! I bet 8" quartz fittings cost a pretty penny though so you won't be saving money there!


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## HAuCl4 (Aug 26, 2010)

Took your idea and drawing and changed it a bit. Crucible inside crucible, and quartz glass disk on top (need good coupling here, but if operated at small vaccuum the seal shouldn't be critical) with the quartz tube fused in one piece. Can add another tube on the left (blue) for the hydrogen, but I think for Pt and Pd not really needed?. (Corfirmation of this?).

It shouldn't cost more than a few hundred dollars plus the temperature adjustable fire assay furnace?. I hope it helps someone.

What do you think 4metals?.

http://advaluetech.com/chemical_processing_crucibles.html

edited to add: I think I wouldn't attempt this with hydrogen feed tube unless I could attain a really good seal on the top between outer crucible and glass disk.


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## 4metals (Aug 26, 2010)

Lou is really the expert on this method. The hydrogen is needed for Pt and Pd. My reasoning for mounting on the door of a kiln was that the 2 quartz glass tubes can be fused to prevent the leakage you are concerned about around the top of the crucible. 

I'm working with a guy that processes a lot of Pd/Ag scrap and has enough metal to reduce using this method. I've been in contact with my glassblower and he is concerned about the top seal in my design as the way I envisioned it was a large (6 or 8") glass stopper on top. He is afraid the condensing gasses will make the sintered glass frit too difficult to remove after processing. He is suggesting a conical opening with a blank cover and a monel clamp. I'm awaiting pricing.

The reduction of platinum and or palladium salts does not require super hot conditions and the reducing atmosphere of the hydrogen does the work. What Steve is suggesting in his tube furnace is for a different application.


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## HAuCl4 (Aug 26, 2010)

Lou said:


> I've done the whole thing with just straight calcination. Works fine for platinum if you go nice and easy, and to a lesser extent Pd and Rh (I usually let them cool under a soft H2 flame).



I was thinking (El-Cheap-O!) to achieve a seal using a 75-25 mix of borax and boric acid in between joints at the top. Using no H2.

To break the seal, after the reduction (calcination really) is complete, rise temperature to 1,200 degC and pull. Can't tell if it'll work till I see it, but I think it will, as borax liquefies a lot in that range from 700 to 1,200 degC.

Lou said that pure calcination will work too (see quote). Probably at much higher temperature (700-800?) than H2 reduction (200-400?).

Maybe one day soon I'll have the metal stuff to really find out for myself!. :roll:


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## Oz (Aug 27, 2010)

It is worth noting that it is best to have fault tolerant seals when dealing with H2 even with exposure to the atmosphere, not to mention a furnace environment.


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## HAuCl4 (Aug 27, 2010)

Oz said:


> It is worth noting that it is best to have fault tolerant seals when dealing with H2 even with exposure to the atmosphere, not to mention a furnace environment.



That's my thinking too. I do not like that high temperature "seal", in either design, very much without H2, and not at all with H2.

If H2 can't be avoided then I'd go for some other design that has no joints at such high temperature.

I'll try to post a couple of diagrams later on how I'd approach it on a budget, but I can't see it being cheaper than avoiding H2 altogether. 

Hoke speaks of calcining both palladium and platinum salts (no H2), but I'm sure there are good reasons for choosing to reduce with H2 at lower temperatures. 

Maybe less losses or purer metal or both, or faster?. I hope Lou, 4metals chime in on why H2 is preferred.


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## 4metals (Aug 27, 2010)

You will have to get much hotter without the H2 than with it. These devices only help you prevent losses, if you want to be el cheapo, you can throw it in a crucible and place it in a gas furnace that is barely hot enough to stay lit. (that is back in the day of forced air gas furnaces)
When the white smoke stops it's done. You will have losses though, the kind you cannot recover, so the el cheapo methods aren't always so cheap.

The tube muffle furnaces don't need a seal but I've never liked the skinny little silica boats to feed the salts into. I guess the boats can get larger in a larger ID tube if the production quantity warrants.


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## HAuCl4 (Aug 27, 2010)

That makes sense. Thanks again 4metals. I'll throw an idea diagram of mine for your evaluation and/or modification in a few minutes for an H2 tube furnace. Please be advised that I do not have practical expertise on processing these metals, and I'm only going with hopefully good engineering common sense gathered from experience in other applications.


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## HAuCl4 (Aug 27, 2010)

Drawing not to scale, of course. Tube is wide enough to load and withdraw the silica boat(s ?) and long enough for the temperature to drop so that a Teflon plug (green) can be used?. The H2 enters on the right through a smaller diameter tube fused to the larger tube and a disk. And a vaccuum to the "glass frits" and scrubber on the left.

I do not have a glassblower to quote me a price, but it looks simple enough to fabricate.

Feel free to criticize, modify, improve, etc, etc. 

If Teflon plug not suitable, I'd like to learn the shape and workings of the glass connection and seal.

I don't know anything about the "glass frits" and how they work either.

Cheers!.


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## HAuCl4 (Aug 28, 2010)

Quartz frits and other quartz products:
http://www.technicalglass.com/product_pages/fused_quartz_wool/fritted_discs.html

They have a price list online, which is both rare and helpful if you are estimating your cost of materials without having to make 343 phone calls.

I have "modified" the design above to make it round on the right side of the big tube. Closing the tube with a flame is much easier than soldering a disk, insert small tube as the hole is closing. Two pieces to join for the glassblower instead of 3.

I wonder how a "removable frit" looks like and the shape of the joints to make and break the connection. Any pictures anyone?.

I guess a 50 mm 00 frit is more than enough for this job?. 

http://technicalglass.thomasnet.com/item/fused-quartz-wool-and-frits/quartz-frits/qpd5000?&seo=110

If you want it all glass instead of the teflon plug, I guess a flange, a tube fused to a hollow disk, a viton gasket, and a mechanical clamp can do the job too on the left side. Piece of cake for a glassblower.


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## HAuCl4 (Aug 28, 2010)

I believe these designs will need the addition of a sublimate chamber to catch the NH4Cl solids from calcination, and I'm not sure about the H2 reduction. As they stand, they are incomplete non-working designs that will likely clog or otherwise fail.

I will try to find out some more about tube furnaces.


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## skippy (Aug 29, 2010)

HAuCl4, you should hollow out the plugging portion of your stopper, otherwise a very slight temperature rise can crack your expensive tube like nothing. 
I learned this lesson the not so hard way, with a $10 round bottom flask's joint cracking after I tried heating it with a solid teflon stopper in place. 

Also quartz doesn't conduct heat very strongly, but the atmosphere in the tube will convect, so you might consider putting some sort of permeable insulation in there to keep heat away from your stopper, like a wad of quartz wool.


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## HAuCl4 (Aug 29, 2010)

Thanks skippy. I think I'll do away with the teflon plug design. A pure glass setup seems better. The glass wool is a great idea to avoid clogging the frit. A look at an actual working rig would help a lot.


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## skippy (Aug 29, 2010)

HAuCl4, once I hollowed out the solid PTFE stopper it was fine - I even took the whole flask stopper and all to 150C. Whereas the solid stopper broke the ground glass joint before it ever hit 50C.
WIth some glass or quartz wool you can keep the plug for your tube cooler than 50C. So Your teflon plug could work fine, although I agree
that if this is something you plan on keeping and using often it'll be worth it to have it built all glass. 

Me, If I were to do teflon I would add a ground taper socket to the end of the tube and plug that with a tapered, hollow teflon stopper. 
On a straight tube, I'd machine it like the flanges here http://www.mtixtl.com/vacuumsealingassemblyfor80-82mmdiatubefurnacewithvalvevacuummeter-eq-fl-82.aspx , but that's getting pretty involved.


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## HAuCl4 (Aug 29, 2010)

Thanks skippy. I'm not sure on the proper design yet.

4metals : How are you going to make the top glass-glass seal effective in your design?. Some type of gasket?. 

Am I correct in that in the "H2 reduction method", there are no sublimates of NH4Cl and the effluents become all gases, whereas in the "calcination method" there are a lot of sublimates of NH4Cl to collect and reclaim?.


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## HAuCl4 (Aug 30, 2010)

Lou: Any chance of a picture of your rig for reduction of Pt in a tube furnace?.


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## Lou (Aug 31, 2010)

I suppose I can post a picture of the tube or some CAD drawings?

Give me some time--busy man lately :-(

Hydrogen, mole for mole is super cheap. You also get a nice gray precipitate. I like 4metals idea as I see the ability to put a tare-able quartz pan or crystallization dish...so I can heat till constant mass. Just make sure you can heat and pull a bit of a vacuum though, it's important to get the absorbed H2 off of the metal. I've lost some hair before to metal that still was H2-saturated. 


Time to get some shuteye.

FYI, I've done a bit of business with TGP, and so too does my glassblower (great guy too!). Best prices. Their shop is pretty good too. TGP is close to home as well


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## HAuCl4 (Aug 31, 2010)

Take your time Lou. I'm in no hurry. CAD drawings would be nice, and a photo(s) of your tube furnace, glass joints, removable frit joints, etc, even better!. 8)


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## HAuCl4 (Aug 31, 2010)

Found these photos on the web for the reduction chamber.


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## HAuCl4 (Aug 31, 2010)

I'm just bored!. :lol:

Yellow is quartz wool, orange is a quartz frit, vaccuum on left, H2 on right. Identical tubes with a gasket and clamp between flanges. A ceramic kiln (or adapted assay furnace for the heat on the right). Left chamber is a sublimate chamber for the solids that should get trapped between the two wool disks. Place silica boats full of Chloroplatinate salts on the right chamber. Fan blowing fresh air on the outside surface of the left chamber.:shock:


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## Mgnaing (Mar 22, 2014)

Which method is the cheapest in reduction of ammonium chloroplatinate to platinum sponge?


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## Lou (Mar 22, 2014)

Heat.


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## Mgnaing (Mar 22, 2014)

Lou said:


> Heat.


Heat method is cheap , but the process is too slow and require about one hour to convert 1kg of platinum salt to sponge. The tungsten heat coin most often break down. Any advise how to overcome this problem?


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## Lou (Mar 23, 2014)

It still takes a half hour to slurry the yellow salt in DI water, make it 2.0 M in NaOH, hook up exhaust system and gas purge and meter in hydrazine hydrate, now doesn't it?

Then you have to filter, rinse, and calcine anyways and all the liquids are hazardous waste (which probably doesn't matter where you're from :-/).


FYI, it takes longer than an hour to convert into sponge, at least properly with an industry-accepted melt loss/LOI that won't make you into a laughing stock. 


Sounds to me like you're complaining to complain.

You don't need tungsten heating elements. In fact, all you need is a quartz tube, a boat lined with magnesia/magnesium silicate, a percolating scrubber/cold finger for the ammonium chloride/HCl off gas and a tube furnace with plain old NiCr (Kanthal). You only want to go to 1000*C and hold there for 5-8 h.
Hydrogen is purely optional on Pt, although I find that you have less Pt volatilize that way and much less corrosive off gas.

Any more with platinum salts, I'm of the opinion that if people have to ask, they probably shouldn't be doing it. Which means less typing for me! Hooray.


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## Mgnaing (Mar 24, 2014)

Yes . Lou , using hydrazine hydrate reducing platinum salt to sponge cost me more , reducing 5 kg of platinum salt cost me about 70 $ not including others chemical . It need to filter and the gas emitted was too bad and also the waste harzardous water too . I have difficult technique in using quartz tube as i am a beginner refiner .


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## Lou (Mar 24, 2014)

You're reducing 160 ounces of platinum and you're worried about 70 dollars?

If you're so cheap, spend the big bucks and get an autoclave and reduce it with hydrogen. That's the cleanest way.


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## Mgnaing (Mar 24, 2014)

thanks to lou and 4 metals and other members from forum for teaching me and give me a lot of advices on refining PGM and gold.


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## 4metals (Jun 29, 2015)

The moderators would like to thank all of the members that contributed to the original thread upon which this thread was based, as well as those that asked questions showing what was missing. Because of the extra length and interest in this thread we have created the above consolidated version making for an easier read. We encourage all members to read, comment, and ask questions in the original thread, Platinum sponge from Hydrazine sulfate

The Library threads should not be considered to constitute a complete education. Instead, they're more like reading a single book on the subject of recovery and refining. There is so much more information on the forum, and it is impossible to include it all in these condensed threads. Members are strongly encouraged to read the rest of the forum to round out their education.


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