Platinum sponge from hydrazine sulfate

[HAuCl4]

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:

 

[HAuCl4]

Hi Lou.

 

[Mgnaing]

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.

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

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.

 

[Mgnaing]

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

 

[Lou]

Heat.

 

[nickvc]

Heat.

:lol:

 

[Mgnaing]

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?

 

[Lou]

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.

 

[Mgnaing]

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 .

 

[Lou]

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.

 

[Mgnaing]

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.

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.

 

[Pen Cen]

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

hey listen to me carefully!!! After you precipitate your Pt with NH4Cl wash it for 10 times with NH4Cl 20% solution
ok?

after that

put your pt yellow orange precipitation Pt in a big beaker and add some water and add hydrazine hydrate ! your solution becomes black ! after that add NaOH 50% solution to your beaker and see all your Pt become to metallic gray powder ! you can add more hydrazine hydrate to complete reaction

I did it for a 10 million times! don’t worry

 

[Justincase]

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

Were those photos of the quarts tube for controlled atmosphere calcining?
If so would it be possible to refresh them, please?
I was toying with the idea of having one made for my tube furnace.
Many thanks.

 

[Alondro]

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).

I'm going to be doing a test run of MLCCs for palladium. What's the exact protocol for the ammonia-formic acid recovery, and what salt form of palladium works with it?

 

[orvi]

I'm going to be doing a test run of MLCCs for palladium. What's the exact protocol for the ammonia-formic acid recovery, and what salt form of palladium works with it?

I usually smelt the lot, obtain metal dore, which is pyrometallurgically pre-cleaned from base metals and then dissolved in nitric. After dissolution, silver is removed, and formate reduction is performed.

I use sodium hydroxide to rough pH adjusting, then sodium hydrogen carbonate for fine tuning. First, you add formic acid (I use 3-4 times excess), then pH adjust to 2 and heat to boiling till all pd forms sponge. Test with stannous or DMG if it is all properly reduced. If there was excess of HCL used in the process, it will produce bit of NOx gasses - i do not know by what exact process, but overall, it does not have very significant effect on the reduction of Pd.
It happened to me recently, that after successful reduction, some other gas evolving process started on the reduced Pd surface, producing some amine/amide like substances, probably catalytically. I recently wrote a post in the Gold refinig Gallery section about it.

Overall, my version is compilation of various bits of information from this forum, and certainly not the best one achievable. But it works for me and results are I think good, efficiency high.
Cleaning from Ag is much more difficult part to do it efficiently I think.

Good luck in your ventures

 

[Alondro]

I usually smelt the lot, obtain metal dore, which is pyrometallurgically pre-cleaned from base metals and then dissolved in nitric. After dissolution, silver is removed, and formate reduction is performed.

I use sodium hydroxide to rough pH adjusting, then sodium hydrogen carbonate for fine tuning. First, you add formic acid (I use 3-4 times excess), then pH adjust to 2 and heat to boiling till all pd forms sponge. Test with stannous or DMG if it is all properly reduced. If there was excess of HCL used in the process, it will produce bit of NOx gasses - i do not know by what exact process, but overall, it does not have very significant effect on the reduction of Pd.
It happened to me recently, that after successful reduction, some other gas evolving process started on the reduced Pd surface, producing some amine/amide like substances, probably catalytically. I recently wrote a post in the Gold refinig Gallery section about it.

Overall, my version is compilation of various bits of information from this forum, and certainly not the best one achievable. But it works for me and results are I think good, efficiency high.
Cleaning from Ag is much more difficult part to do it efficiently I think.

Good luck in your ventures

So this will work with Pd dissolved in nitric?

I would first drop the Ag with HCl, in that case. Then add enough for palladium chloride to form. Then denox.

Now, after this, according to your description, I need to first raise the pH high with NaOH and baking soda, and then add formic acid, after which I must adjust the pH to 2... with HCl, I'm guessing?

Then once the pH is 2, boil until the gray sponge forms.

Is that about right?

 

[orvi]

So this will work with Pd dissolved in nitric?

I would first drop the Ag with HCl, in that case. Then add enough for palladium chloride to form. Then denox.

Now, after this, according to your description, I need to first raise the pH high with NaOH and baking soda, and then add formic acid, after which I must adjust the pH to 2... with HCl, I'm guessing?

Then once the pH is 2, boil until the gray sponge forms.

Is that about right?

With AgCl separation, it isnt that easy to do it sharply. It was discussed here numerous times, that AgCl tend to trap PdCl2 as PdCl2 is also relatively low soluble. You need to thoroughly wash the brownish AgCl with dilute HCL to free Pd as PdCl4 2- anions which are soluble.

I first add formic acid and then neutralize with solid NaOH. You need good stirring, best magnetic stirrer to equilibrate formed base metals hydroxidez which form on contact with lye. With heavy BM solutions it is better to add lye as solution.

Sometimes you obtain sponge, sometimes nearly powder. In all cases nicely filterable, in my cases never catched fire on drying, but stay cautious.

 

[Alondro]

With AgCl separation, it isnt that easy to do it sharply. It was discussed here numerous times, that AgCl tend to trap PdCl2 as PdCl2 is also relatively low soluble. You need to thoroughly wash the brownish AgCl with dilute HCL to free Pd as PdCl4 2- anions which are soluble.

I first add formic acid and then neutralize with solid NaOH. You need good stirring, best magnetic stirrer to equilibrate formed base metals hydroxidez which form on contact with lye. With heavy BM solutions it is better to add lye as solution.

Sometimes you obtain sponge, sometimes nearly powder. In all cases nicely filterable, in my cases never catched fire on drying, but stay cautious.

Would that PdCl problem be solved if the AgCl is dropped by HCl in the first place? Or if the solution was more aqueous? I did a test recently with a small batch of MLCCs, and I think I hit a solubility sweet spot.

After removing base metals with HCl, washing in distilled twice, and then dissolving the Ag and Pd with dilute nitric, I added plain salt water dropwise. The AgCl dropped perfectly white, and left PdCl(2 or 4) in pale yellow-orange solution. The stannous test for Pd is here:

I will be buying some DMG for a secondary positive test, but that stannous test was VERY strongly positive, so I think it's legit.

 

[orvi]

Would that PdCl problem be solved if the AgCl is dropped by HCl in the first place? Or if the solution was more aqueous? I did a test recently with a small batch of MLCCs, and I think I hit a solubility sweet spot.

After removing base metals with HCl, washing in distilled twice, and then dissolving the Ag and Pd with dilute nitric, I added plain salt water dropwise. The AgCl dropped perfectly white, and left PdCl(2 or 4) in pale yellow-orange solution. The stannous test for Pd is here:

I will be buying some DMG for a secondary positive test, but that stannous test was VERY strongly positive, so I think it's legit.

Yeah, with this quantity/ratio/concentration of Pd to Ag, not a big issue. Positive thing is not much Ag is washed out of AgCl with dilute HCL washings. Sad thing is you can add as slow as you can, you always produce yellowish AgCl - if you are doing say 1:2 Pd:Ag ratio in concentration of like 15-20g/L Pd (workable concentration for small batch refining). Second technique is to drop the AgPd nitrate solution into large excess of conc. HCL - by doing this, adsorption is somewhat lowered, but not eliminated.


Photo shot with said concentration (ca 15g/L Pd) after cautious drop of AgCl. After 3 careful and thorough washings AgCl still contained 0,5% Pd by XRF and still orange-y juice dripping out of it...

 

[rusti2]

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).

Lou, after removing the ammonium chloride without reducing the temperature, inject a gas mixture with hydrogen or pure hydrogen, should it be under overpressure or at atmospheric pressure?.